Download The inferior alveolar nerve block is the most

Anesthetic Efficacy of a Labial plus Lingual Infiltration Compared to a
Labial Infiltration using Articaine in Mandibular Anterior Teeth.
A Thesis
Presented in Partial Fulfillment of the Requirements for
The Degree of Master of Science in the
Graduate School of The Ohio State University
By
Frederick Micah Nuzum, D.D.S.
Graduate Program in Dentistry
The Ohio State University
2009
Master’s Examination Committee
Dr. Melissa Drum, Advisor
Dr. John M. Nusstein
Dr. Al Reader
Dr. F. Michael Beck
Copyright by
Frederick Micah Nuzum, D.D.S.
2009
ABSTRACT
The purpose of this prospective, randomized, single-blinded study was to
determine the anesthetic efficacy of a combination labial plus lingual infiltration
compared to a labial infiltration using 4% articaine with 1:100,000 epinephrine in
mandibular anterior teeth. Eighty-two subjects randomly received mandibular lateral
incisor infiltrations, either a combination of labial and lingual (totaling 3.6 mL) or labial
and mock (totaling 1.8 mL), utilizing cartridges of 4% articaine with 1:100,000
epinephrine at two separate appointments spaced at least 1 week apart. In mandibular
lateral incisors, the labial and lingual combination exhibited a significantly higher
anesthetic success rate of 98% success when compared with a 76% success rate with the
single labial infiltration. Similarly, the central incisor and canine adjacent to the
infiltrations exhibited significantly higher anesthetic success rates when compared with
the single infiltration. In conclusion, a mandibular infiltration combining a labial and
lingual cartridge of 4% articaine with 1:100,000 epinephrine statistically improved
anesthetic success when compared with a single labial infiltration with 4% articaine with
1:100,000 epinephrine.
ii
Dedicated to my wife- Your unconditional love and encouragement, and your eternal perspective and
support for me have been a benchmark through all of this educational journey. You are the rarest
treasure and a lifelong gift. Philippians 1:3
I love you.
iii
ACKNOWLEDGMENTS
I wish to specially thank my advisor, Dr. Melissa Drum. Thank you for your
encouragement, positive attitude and reinforcement. You are a great teacher and listener
and your quest for knowledge, excellence, and fun shows through in all of your teaching
efforts.
I thank Dr. Al Reader for your experience and practical knowledge. Your humor and
wisdom is an integral part to the success and sustenance of this excellent program. Thank
you for letting me be a part of your “endo” family. I promise to put a few more hours
into refining my golf skills in the following years!
I thank Dr. John Nusstein for giving me the opportunity to learn and achieve skills that I
would not have found in any other program. For keeping the fires hot – to learn faster
and more predictable endodontic skills to get the job done.
I thank Dr. William Meyers for your absolute devotion and willingness to make others
succeed. Thanks for your wisdom, kindness, and legacy. May your sharp mind continue
to guide and support this program.
I thank Dr. Michael Beck for your commitment and support. Thank you for making
statistics, though almost in all regards a foreign language to me, understandable,
purposeful, and useful. Your search for the truth and accuracy comes through with
clarity.
I thank my co-residents Aaron Aue, Mayes McEntire, and Mark Oleson. May your lives
be rich with blessing and success in all that you pursue.
iv
VITA
2002………………………………………B.A. The Ohio State University
2006………………………………………D.D.S. The Ohio State University
2009……….……………………………..Specialization in Endodontics
Post-Doctoral Certificate,
The Ohio State University
FIELDS OF STUDY
Major Field: Dentistry
Specialization: Endodontics
v
TABLE OF CONTENTS
Page
Abstract…………………………………………………………………………………...ii
Dedication………………………………………………………………………………...iii
Acknowledgments………………………………………………………………………..iv
Vita………………………………………………………………………………………..v
List of Tables……………………………………………………………………………viii
List of Figures……………………………………………………………………………..x
Chapters:
1. Introduction……………………………………………………………………………..1
2. Literature Review………………………………………………………………………5
Mechanism of Action of Local Anesthetics……………………………………....5
Pharmacology of Local Anesthetics........................................................................8
Vasoconstrictors in Local Anesthetics......……………………………………….11
Articaine.................................................................................................................14
Safety…………....…....………………………………………………….18
Efficacy, Onset Time, and Duration of Articaine for Mandibular
Infiltration injections……………………………………………..30
Mandibular Anesthesia: Articaine for Inferior Alveolar Nerve Block….……….40
Mandibular Infiltration Injection………………………………………………...44
Posterior Infiltration……………………………………………………..44
Anterior Infiltration………………………………………………………52
The Electric Pulp Tester………………………………………………………….56
The Visual Analogue Scale………………………………………………………59
Topical Anesthetic……………………………………………………………….60
3. Materials and Methods………………………………………………………………...64
4. Results…………………………………………………………………………………72
5. Discussion …………………………………………………………………………….78
Discussion of Materials and Methods……………………………………………78
Discussion of Results..........................................................................................102
Discussion of Age......…………..………………………………………103
Discussion of Weight Related to Dosage of Articaine……….….……..103
vi
Discussion of Gender Related to Pain and Anesthesia…………………104
Pain of Injection………………………………………………………...109
Pain on Needle Insertion….…………………………………….109
Pain on Needle Placeement……………………………………..115
Pain on Solution Deposition…………………………………….117
Anesthetic Efficacy…………………………...........................................131
Frequency of Pulpal Anesthesia……………………....………...132
Anesthetic Success………………………………………...........141
Anesthetic Failure……………………………………………….155
Onset of Pulpal Anesthesia……………………………………...159
Slow Onset of Anesthesia, Short Duration of Anesthesia,
and Noncontinuous Anesthesia…………………………163
Duration of pulpal anesthesia…………………………………………...168
Postoperative Pain………………………………………………………172
Postoperative Complications…………………………………...177
6. Summary and Conclusions…………………………………………………………..182
Appendices
A.
B.
C.
D.
E.
F.
G.
H.
Tables…………………………………………………………...187
Figures………………………………………………………….208
Biographical Data………………………………………………212
Health history questionnaire……………………………………214
Consent…………………………………………………………217
HIPAA………………………………………………………….226
VAS form and raw VAS pain score data……………………….230
Electric pulp testing form and raw EPT data…………………...242
References…………………………………………………….………….……...…...….237
vii
LIST OF TABLES
Table
Page
1.
Biographical Data for All Subjects……………..…………………....………….188
2.
Mean VAS Values (mm) of Procedural Discomfort Ratings for Groups by
Location of Injection, Step of Injection, and Gender...........................................189
3.
Summary of Pain Ratings for Needle Insertion Utilizing
Numerical Scale...................................................................................................190
4.
Summary of Pain Ratings for Needle Placement Utilizing
Numerical Scale...................................................................................................191
5.
Summary of Pain Ratings for Anesthetic Deposition Utilizing a
Numerical Scale...................................................................................................192
6.
Between-Group Comparisons of Percent 80/80 for the Lateral Incisor..............193
7.
Between-Group Comparisons of Percent 80/80 for the Central Incisor.....…….194
8.
Between-Group Comparisons of Percent 80/80 for the Canine…………..…....195
9.
Anesthetic Success by Group and Definition of Success………………………196
10.
Anesthetic Failure by Tooth and Group …..........................................................197
11.
Mean Onset (minutes) of Pulpal Anesthesia ………………………………..….198
12.
Short Duration Anesthesia, Non-Continuous Anesthesia, and
Slow-Onset by Group and Tooth………………………………………….……199
13.
Mean VAS Values (mm) of Postoperative Discomfort Ratings for Groups by
Gender…………………………………………………………………………..200
14.
Summary of Pain Ratings for Post-op Day 0 Utilizing a Numerical Scale…….201
viii
15.
Summary of Pain Ratings for Post-op Day 1 Utilizing a Numerical Scale.........202
16.
Summary of Pain Ratings for Post-op Day 2 Utilizing a Numerical Scale….....203
17.
Summary of Pain Ratings for Post-op Day 3 Utilizing a Numerical Scale….....204
18-1. Frequency of Subject-Reported Postoperative Complications by Day......... ......205
18-2. Frequency of Subject-Reported Postoperative Complications by Day…...…….206
19.
Postoperative Complications Associated with Articaine Infiltration
Injection for Groups by Location…………………….………….……………...207
ix
LIST OF FIGURES
Figure
Page
1.
Percentage of 80 Readings for the Lateral Incisor by Group and Time………..209
2.
Percentage of 80 Readings for the Central Incisor by Group and Time….…….210
3.
Percentage of 80 Readings for the Canine by Group and Time………..………211
x
CHAPTER 1
INTRODUCTION
The inferior alveolar nerve block is the most frequent injection used for
achieving local anesthesia for both restorative and surgical procedures in the mandible.
Yet, the inferior alveolar nerve (IAN) block does not always result in successful pulpal
anesthesia (1-12). Anesthetic failure rates in anterior teeth have ranged from 10-90%
(1-12).
Recently, infiltration anesthesia has been advocated to supplement regional
blocks, due to failure of inferior alveolar nerve blocks to achieve pulpal anesthesia in
mandibular teeth (3, 4, 9, 13-15). Research has shown that buccal infiltrations of
lidocaine and prilocaine solutions are not very effective for pulpal anesthesia in adult
mandibular posterior teeth (16, 17). In the posterior mandible, infiltrations have
indicated greater anesthetic success utilizing articaine when compared to lidocaine (14,
15, 18). A recent study by Kanaa et al. (18) compared a cartridge of 2% lidocaine with
1:100,000 epinephrine to a cartridge of 4% articaine with 1:100,000 epinephrine for
buccal infiltration anesthesia of the mandibular first molar. The articaine solution had a
significantly higher success rate (presence of two consecutive 80 readings with the
electric pulp tester) of 64% when compared to the lidocaine solution, having only a
1
39% success rate (18). Robertson et al. (14), using an infiltration injection, also found
an articaine solution statistically superior (87% success rate) to a lidocaine solution
(57% success rate) in mandibular first molar anesthesia.
Haase (19) compared the difference in efficacy of articaine and lidocaine when
given as a mandibular buccal infiltration in patients with asymptomatic, vital
mandibular molars. The study compared the degree of pulpal anesthesia obtained with
4% articaine with 1:100,000 epinephrine and 2% lidocaine with 1:100,000 epinephrine
in buccal infiltrations of the mandibular first molar following an inferior alveolar nerve
block administered with 4% articaine with 1:100,000 epinephrine. The first molar had
65% anesthetic success with lidocaine and 84% anesthetic success with articaine. The
first molar showed a statistically significant difference for the articaine solution when
compared to the lidocaine solution when evaluating anesthetic success, as defined by
continuously sustaining an 80/80 reading on an electric pulp tester for 60 minutes.
Following the inferior alveolar nerve block, Foster et al. (17) found neither the buccal or
lingual supplemental injections of a cartridge of 2% lidocaine with 1:100,000
epinephrine solution produced significant increases in anesthetic success in the posterior
mandible. The results showed a slight increase in anesthesia, primarily with a buccal
infiltration, but this was not statistically significant (17). The results support the fact
that lidocaine infiltration has some effect on pulpal anesthesia, while not increasing
success significantly. Therefore, infiltration anesthesia using an articaine solution,
rather than a lidocaine solution, has demonstrated greater efficacy in the mandibular
first molar.
2
When considering the mandibular anterior teeth, labial or lingual infiltration
injections alone have not been found to be very effective for pulpal anesthesia (13, 16,
20, 21). Meechan and Kanaa et al. (22) found buccal infiltration (1.8 mL) was more
successful (39%) when compared to a combined buccal (0.9 mL) and lingual infiltration
(0.9 mL) of 2% lidocaine with 1:100,000 epinephrine in the mandibular first molar
(though the difference was not statistically significant). In anterior teeth, Meechan and
Ledvinka (13) found that a combination of a labial (0.5 mL) and lingual infiltration (0.5
mL), using 2% lidocaine with 1:80,000 epinephrine, significantly increased success,
when compared to either a labial or lingual infiltration (1.0 mL) alone. After
administration of the labial or lingual infiltration alone, anesthetic success reached only
50% (13).
Yonchak et al. (21) compared the anesthetic efficacy of mandibular lateral incisor
infiltrations using either 1.8 mL of 2% lidocaine with 1:100,000 epinephrine or 1.8 mL of
2% lidocaine with 1:50,000 epinephrine at two separate appointments in 40 subjects.
Additionally, 40 subjects were given a lingual infiltration of 1.8 mL of 2% lidocaine with
1:100,000 epinephrine. Anesthesia was considered successful when two consecutive 80
readings were obtained. The anesthetic success (two consecutive 80 readings) for the
lateral incisor ranged from 43-50% for all three infiltrations.
In 1990 and 1991, Haas et al. (16, 20) investigated the claim that anesthesia of
mandibular pulpal and lingual soft tissue results following buccal infiltration of the
articaine local anesthetic. The authors’ aim was to scientifically test these claims by
comparing 1.5 mL 4% articaine HCl with 1:200,000 epinephrine to 1.5 mL 4% prilocaine
HCl with 1:200,000 epinephrine. They found that articaine was able to penetrate deep
3
into the tissue to result in lingual soft tissue anesthesia, at least in some subjects. Twenty
healthy adult volunteers had the anesthetic solutions infiltrated next to the canine and
contralateral canine. Efficacy was evaluated by electric pulp tester readings for 25
minutes. Additionally, differences related to soft tissue anesthesia were also analyzed.
“Lingual tissues were not expected to be anesthetized with use of a buccal infiltration
alone. Results for mandibular canines showed that articaine achieved successful pulpal
anesthesia in 65% of the subjects compared to 50% for prilocaine. Lingual tissues
achieved anesthesia 10% of the time with articaine compared to 5% with prilocaine.”(23)
These differences, however, were not found to be statistically significant. Overall,
articaine has shown a tendency towards an increased efficacy in infiltration injections of
mandibular anterior teeth.
With the success of articaine infiltrations in both pulpal anesthesia and onset (14,
18) in the posterior mandible and evidence for greater efficacy in the anterior mandible
(16, 20), articaine infiltration in the mandibular anterior teeth should be studied further.
Therefore, the purpose of this prospective, randomized, single-blinded study was to
determine the anesthetic efficacy of a combination labial plus lingual infiltration
compared to a labial infiltration using 4% articaine with 1:100,000 epinephrine in
mandibular anterior teeth.
4
CHAPTER 2
LITERATURE REVIEW
Selected portions of the following have been adapted from previous theses by
Stein (24), Robertson (25), Haase (19), Mikesell (26), Pabst (27), and Matthews (23)
from the Division of Endodontics at The Ohio State University College of Dentistry.
LOCAL ANESTHETICS
Mechanism of Action of Local Anesthetics
“The primary action of a local anesthetic is interference with the excitationconduction process of nerve fibers and endings (28). A nerve fiber has the capability to
respond to a stimulus by excitation and to propagate this stimulus along the nerve fiber to
its point of termination (29). This conduction of the stimulus is temporarily interfered
with by the action of the local anesthetic (28).
The electrophysiological properties of the neuronal membrane rely on both the
permeability of the membrane to specific electrolytes and to the concentration of these
electrolytes in the cytoplasmic and extracellular fluid (28). A nerve cell membrane is
fully permeable to potassium and chloride ions in its resting state and relatively
5
impermeable to proteins, amino acids, and sodium ions (30, 31). As a result of this
selective permeability, cations (+) including sodium ions are concentrated extracellularly
and anions (-), potassium ions, are concentrated intracellularly. The permeability of the
nerve cell membrane along with the cytoplasmic and extracellular electrolyte
concentrations combine to determine the electrophysiologic properties of the nerve cell
membrane. The electrochemical gradient set up between the inside of the nerve
membrane and the outside results in an electrical potential of approximately -70 to -90
mV across the cell membrane (32). Stimulating the nerve results in an increased sodium
permeability through a transitory widening of the transmembrane channels. This
widening allows sodium ions to rapidly diffuse to the interior of the cell resulting in
depolarization of the neural cell membrane to a firing threshold of approximately -50 to
60 mV. Upon reaching the firing threshold, sodium permeability increases remarkably
and a rapid influx of sodium ions occurs across the cell membrane. At the end of the
depolarization phase, the electrical potential is actually reversed across the membrane to
approximately +40 mV (30, 31).” (25)
“Once depolarization is complete, the permeability of the nerve membrane to
sodium ions decreases and the high permeability to potassium is restored. The resulting
movement of the sodium ions out, and the potassium ions in, by passive diffusion,
restores the normal resting potential of the nerve cell membrane. When the resting
potential is achieved, there is excess of sodium ions intracellularly and of potassium ions
extracellularly (32). The "sodium pump" actively transports the excess sodium ions out
of the cell. This process is energy dependent, the source being adenosine triphosphate
(ATP), which is oxidatively metabolized to provide the necessary energy (31, 32). Once
6
the normal ionic gradient is restored, the nerve is again in its resting state. This
repolarization process takes approximately 0.7 msec, after which the nerve cell
membrane re-achieves its normal resting potential of approximately -90 mV (31).
The exact mechanism of action of local anesthetics is not known. The presently
accepted theory on the action of local anesthetics is that they prevent depolarization by
blocking the transmembrane sodium channels (30, 31, 33-38). This is believed to be
accomplished by either of the following mechanisms: the specific receptor mechanism
and/or the membrane expansion mechanism (30, 31, 33-38).”(24)
“The specific receptor theory is based on four proposed binding sites within the
sodium channel, to which local anesthetic molecules can attach. Molecules may bind to
the inner mouth of the channel pore resulting in a tonic block. Binding to a second site
deeper within the pore will result in a use-dependent block (38). The other two proposed
sites are located at the gate of the sodium channel and are related to the action of scorpion
venom (33). Only the charged, or ionized, forms of the local anesthetic can bind to these
sites and this form is unable to cross the nerve membrane (32, 36, 38). The unionized
form of the local anesthetic diffuses across the membrane thus establishing a chemical
equilibrium. Once the unionized form of the local anesthetic has entered the cell,
approximately 75% of it is converted to the ionized form. It is this ionized form of the
anesthetic molecule that is capable of binding to the receptor sites resulting in decreased
membrane permeability to sodium and leading to a prevention of the firing of the
membrane (31, 32, 36).
The second theory, known as the membrane expansion theory, states that the
anesthetic agent acts by penetrating the nerve membrane, resulting in an expansion of the
7
membrane and a decrease in the diameter of the sodium channel, thereby preventing
sodium permeability (31, 32, 37). This theory offers an explanation for the action of
anesthetics that do not exist in the ionized form such as benzocaine (31).” (24)
Pharmacology of Local Anesthetics
“Local anesthetics are agents, which produce a loss of sensation, or feeling, when
injected or applied to a particular area of the body (32). These agents inhibit the
excitation-conduction process of the nerve endings and fibers in a reversible manner (32).
The chemical composition of local anesthetics consists of an aromatic group with
an ester or amide linkage to an intermediate hydrocarbon chain, and a secondary or
tertiary amino group (32, 34). The local anesthetic's hydrophilic properties are due to the
secondary or tertiary amino groups, while the lipophilic properties are derived from the
aromatic residue, which originates from benzoic acid or aniline (34). Either an ester or
an amide linkage between the aromatic residue and the intermediate carbon chain
determines the anesthetics metabolism, allergenicity, and classification (34, 39).
Esters or procaine-like anesthetics undergo hydrolysis in the plasma by
pseudocholinesterase and, to a lesser degree, by esterases in the liver (32, 34). This
hydrolysis produces para-amino benzoic acid as its primary metabolite, which is capable
of inducing allergic reactions in a small percentage of the general population (31, 32).
The liver is the primary site for enzymatic degradation of the amide or lidocainelike anesthetics. This metabolism is carried out by the liver microsomes with initial N8
dealkylation of the tertiary amino terminus followed by hydrolysis of the resulting
secondary amine by hepatic amidase activity (34, 40). Reports of allergic reactions to
amide anesthetics are extremely rare, as they are not metabolized to para-amino benzoic
acid (28). The kidneys primarily carry out excretion of amide and ester drugs and their
metabolites (31, 39, 41).”(23)
“The anesthetic properties of each compound are dependent on its lipid solubility,
protein binding capacity, pKa, pH, tissue diffusibility, and intrinsic vasodilating
properties (28).
The potency of the anesthetic compound is primarily determined by its ability to
penetrate the nerve cell membrane, which is directly related to its lipid solubility. Highly
lipid soluble anesthetic compounds can easily penetrate the nerve membrane thereby
requiring lower concentrations to produce adequate anesthesia (31, 32, 41). Lidocaine
and articaine are considered to be of intermediate potency.
Duration of action is primarily determined by the local anesthetics protein-binding
characteristics. The stronger the binding ability of the local anesthetic, the longer the
duration of action. Poor protein binding results in a short duration of anesthesia.
Lidocaine has intermediate duration of action (32, 33).”(19) Articaine has one of the
greatest protein binding potentials of all amide local anesthetics, comparable to that of
bupivacaine, which may lend to longer duration in the jaws (42).
“A chemical compound's pKa is defined as the pH at which the ionized and
unionized forms exist in equilibrium. The pKa is constant and ranges from low for
mepivacaine at 7.6 to high for procaine at 9.1 (31, 32, 34, 39). Lidocaine has a pKa of
7.9, and articaine has a pKa of 7.8. It is the unionized form of the drug that penetrates the
9
neuronal membrane(28). At a tissue pH of 7.4, 2-40% of the drug will exist in the
unionized form. The onset time of the agent is also related to the pKa. The lower the pKa
value, the faster the onset time. Lidocaine and articaine have a relatively fast clinical
onset time (from one to three minutes for maxillary infiltration and one to four minutes
for IANB) because their pKas are close to the pH of the tissue (32, 33, 43).” (19)
“Anesthetic compounds can only act on nerve membranes after they diffuse
through non-nervous tissue and contact the nerve. Tissue diffusibility has been shown to
have a direct relationship on the rate of onset. Despite its importance, the factors that
determine the rate of diffusibility through non-nervous tissues are poorly understood (28).
The vasodilator activity of anesthetic compounds influences potency and duration. The
increased blood vasodilatation, caused by the anesthetic will in turn result in the quicker
removal of the anesthetic compound from the injection site; thereby decreasing the
amount of anesthetic available to act upon the nerve. With the exception of cocaine, all
local anesthetic agents have vasodilator properties (32).
Cartridges of local anesthetic compounds exist in the form of a hydrochloride salt
solution, which is stable for long periods of time (32). These preparations have a pH of
4.5-6.0 (40). Because the compounds have pKa values greater than these pH values,
most of the solutions are in the ionized form. This form is more water-soluble and
diffuses through the non-nervous tissue more rapidly (32, 40). A rapid buffering by the
tissues increases the pH and increases the amount of free base, which is able to diffuse
through the nerve sheath (31, 32).
Various evaluations of local anesthetic toxicity have been reported. The earliest
and most common response to a local anesthetic overdose is CNS excitation. Initially, a
10
feeling of light-headedness or dizziness occurs. Auditory and visual disturbances may
also be noted. The patient may become disoriented and develop slurred speech, tremors,
muscle twitching and generalized convulsions. Generalized CNS depression follows,
with loss of consciousness and respiratory arrest. With doses three to six times higher, the
cardiovascular depressant effects of local anesthetics, such as decreased myocardial
contractility, decreased peripheral resistance, hypotension, and circulatory collapse, will
also be seen (34).” (23)
Vasoconstrictors in Local Anesthetics
“All local anesthetic agents produce some vasodilation, therefore,
vasoconstrictors are added to local anesthetics to counteract this effect. Vasoconstrictors
are drugs capable of constricting blood vessels. They are classified as sympathomimetics
or adrenergic agents because their mode of action resembles the response elicited when a
sympathetic nerve is stimulated. Vasoconstrictors produce the following effects in local
anesthetics: prolong their action, improve the depth of anesthesia, reduce the peak plasma
concentrations of the anesthetic agent, and reduce the amount of hemorrhage in the
injected area (31-34, 39, 43-45).
The vasoconstrictors limit blood flow to the injection site by constricting the
lumens of the blood vessels. This enables a higher concentration of local anesthetic to
remain at the injection site longer, acting to increase the quality and duration of
anesthesia. In addition, the ability of the vasoconstrictor to produce hemostasis at the site
of administration also makes them an adjunct in dental surgical procedures (32, 43-46).
11
The most commonly used vasoconstrictors in dental local anesthetics are
epinephrine and levonordefrin (43). Alpha and beta-receptors are directly affected by
epinephrine, although the beta effects predominate. On the other hand, levonordefrin
predominantly affects alpha-receptors with less beta activity. Levonordefrin is only 15%
as effective as epinephrine as a vasopressor (31, 43, 44). The local and systemic effects
of the vasoconstrictors are a result of their alpha and beta stimulating properties.
Stimulation of alpha-receptors results in smooth muscle contraction of peripheral
blood vessels (vasoconstriction). Beta-1 stimulation increases systolic and diastolic
blood pressure, heart rate, strength of contraction, stroke volume, cardiac output, and
myocardium oxygen consumption. Beta-2 stimulation causes bronchodilation and
vasodilation in skeletal muscle (44-46).”(23)
“When local anesthetics containing epinephrine are injected intraorally,
vasoconstriction occurs as the alpha effects predominate. This vasoconstriction response
causes decreased regional blood flow. The duration and efficacy of the local anesthetic
are then enhanced. As the local epinephrine concentration diminishes, the alphaadrenergic effects subside and the beta effects begin to predominate. This results in
increased local blood flow and the hemostatic effect caused by epinephrine is lost (43).
Normal dental doses of epinephrine are from 18 to 72 µg. This amount of
epinephrine is that found in one to four cartridges (1.8 mL in a cartridge) of 2% lidocaine
with 1:100,000 epinephrine. The maximum recommended dose of epinephrine for the
healthy adult per office visit is 200 µg or 20 mL of a 1:100,000 concentration (the
equivalent of 11 dental cartridges of 1.8 mL each). Forty micrograms, 4 mL of a
1:100,000 concentration or 2.2 cartridges, is the recommended maximum dose for those
12
with "clinically significant cardiac impairment" (31). A 1:100,000 solution of
epinephrine contains 10 µg of epinephrine per ml of solution or 0.01 mg/mL. A 1:50,000
solution of epinephrine contains 20 µg/mL of solution and a 1:200,000 solution contains
5 µg/mL.” (23)
“An overdose of epinephrine results in CNS symptoms of fear and anxiety,
tension, restlessness, throbbing headache, tremor, weakness, dizziness, pallor, respiratory
difficulty, and palpitations. Signs of overdose include sharp elevation in blood pressure
(primarily systolic), elevated heart rate, and possible cardiac arrhythmias, including
paraventricular contractions and ventricular fibrillation. As blood levels of the drug rise,
the incidence and severity of the cardiac arrhythmia increase. Systolic blood pressure in
excess of 300 mm Hg and diastolic pressures in excess of 200 mm Hg may lead to
cerebral hemorrhage. In patients with coronary insufficiency, an overdose results in
anginal episodes (31).
Contraindications to vasoconstrictors in the concentrations found in dental local
anesthetics are few in number. Vasoconstrictors should be used with caution in patients
with hypertension, cardiovascular disease, and hyperthyroidism. These patients may be
particularly sensitive to the pressor effects of the vasoconstrictors (31, 34, 44).
Contraindications as a result of drug interactions have also been proposed.
Known drug interactions between vasoconstrictors and monoamine oxidase inhibitors
(MAOIs), tricyclic antidepressants, phenothiazines, and beta-blockers have been reported
(33, 43, 47-49). However, it has been shown that the concomitant use of epinephrine,
levonordefrin, and norepinephrine with MAOIs or phenothiazines is not contraindicated
(48). Vasoconstrictors may also be used in patients taking tricyclic antidepressants but
13
the dosage should be kept to a minimum (0.05 mg). Medical conditions such as
thyrotoxicosis and pheochromocytoma are absolute contraindications to the use of
epinephrine (43, 50).” (23)
ARTICAINE
“Carticaine [4-methyl-3(2[propylamino] propionamido)-2 thiophenecarboxylic
acid, methyl ester hydrochloride] was first synthesized in 1969 by H. Rushing et al. when
experimenting with thiophene derivatives. The drug was approved for use in both
Germany and Switzerland in 1976 and had its name changed from carticaine to articaine.
Approval for use of articaine was granted in Canada in 1983 and in the United Kingdom
in 1998 (51). Articaine is commonly used by dentists outside of the United States. In
Germany, articaine accounts for 90% of all local anesthetics used (52). In Canada, a
1993 survey shows that articaine was the most frequently used local anesthetic,
accounting for almost 38% of all dental injections (53).
Articaine has similar actions to other local anesthetics currently available. Like
other amide local anesthetics (e.g. lidocaine), articaine blocks sodium and potassium
channels in the nerve membrane to an extent that the nerve resting membrane potential
cannot reach the electrical threshold needed to fire an action potential (54). This disables
the nerve from sending a signal to the brain (55). The addition of epinephrine produces
localized vasoconstriction which slows absorption of articaine and ensures prolonged
maintenance of an active tissue concentration of the anesthetic while minimizing the
systemic absorption of both active compounds (54).” (26)
14
“On April 3, 2000, the Food and Drug Administration (FDA) approved articaine
for use in the United States. The articaine formulation that gained approval in the United
States is a 4% solution and contains a 1:100,000 concentration of epinephrine. The
formulation is known as Septocaine (Septodont, Inc., New Castle DE). Septocaine is
distributed in a 1.8 mL dental cartridge and contains many components with specific
functions. The components are: articaine hydrochloride 40 mg/mL as the local
anesthetic, epinephrine tartrate 0.018 mg/mL for vasoconstriction, sodium chloride 1.6
mg/mL for isotonicity, sodium metabisulphite 0.5 mg/mL as an antioxidant for the
vasoconstrictor, and distilled water 1.0 mL volume for injection (51). Original articaine
formulations contained a bacteriostatic agent, an antifungal agent, and methylparaben as
an antioxidant preservative for the local anesthetic. Methylparaben has a high potential
for allergenicity and it was not until 1994 that methylparaben was removed from articaine
formulations sold in Canada. A similar (methylparaben-free) formula is sold in the
United States (56).
Articaine is classified as an amide, similar to lidocaine and all other local
anesthetics currently available in dentistry. Articaine has a molecular weight of 320.84
and has an intermediate chain that has a trivalent bonded nitrogen which is attached to a
carboxylic acid (51). Articaine, however, differs from all other amide local anesthetics in
that it is derived from thiophene. The molecule does not contain a benzene ring as do
other amide local anesthetics but instead contains a thiophene ring. A second molecular
difference between articaine and other amide local anesthetics is an ester linkage that is
incorporated into the articaine molecule (51).” (26)
15
“Borchard et al. (57) studied the action of local anesthetics on myelinated nerve
fibers. He stated that a lower concentration of a thiophene derivative (articaine) was
needed to block an action potential than was necessary when using a benzene derivative
(all other amide anesthetics.)
Degradation of articaine is initiated by hydrolysis of the carboxylic acid and ester
groups to give free carboxylic acid (54, 58). Articainic acid is the primary metabolite
(58). Additional metabolites, including articainic glucoronic acid, have been detected in
animal studies (51). In comparison to lidocaine, which has active metabolites, it is still
unclear if articainic acid has biological activity. This finding is important because an
active metabolite may affect toxicity and many exert undesirable effects (51). Van Oss et
al. (57) administered articainic acid, intravenously, to a single volunteer to determine the
clinical effects and pharmacokinetics of the major metabolite of articaine. They found no
change in electrocardiography, blood pressure, and heart rate in the subject. The sample
size from the study was only one, however, it does show that the metabolite may be
inactive in comparison to the active metabolites found after breakdown of lidocaine. The
other metabolite, articainic acid glucoroide, also appears to be inactive (51).”(26)
“High performance liquid chromatography has been used to determine the
concentrations of articaine and its metabolite, articainic acid in the serum. Oertel and
Rahn (58) studied the clinical pharmacokinetics of articaine and found that the time to
maximum drug concentration of articaine occurs about 10 to 15 minutes after submucosal
injection of an 80 mg, 4% articaine solution, irrespective of the addition of epinephrine.
They also found that the mean maximum plasma drug concentration to be about 400
micrograms/L for articaine with 1:200,000 epinephrine and 580 micrograms/L for
16
articaine without epinephrine. Oertel and Rahn (58) concluded that the rapid breakdown
of articaine to its inactive metabolite articainic acid results in a very low systemic toxicity
giving articaine a wide therapeutic range. They also concluded that articaine can be
safely administered using repeated doses because the use of articaine in higher doses is
safer than other amide-type local anesthetics. Isen et al. (51) also concluded that reinjection with articaine is safe after 30 minutes if the patient requires additional local
anesthetic since the majority of the initial dose would have already been metabolized. If
more lidocaine were administered 30 minutes after the first injection, it would be adding
to the first dose because its half-life is 3 times longer than articaine.”(26)
“Biotransformation of articaine occurs in both the plasma (hydrolysis by plasma
cholinesterase) and the liver (hepatic microsomal enzymes) (54). It has been shown (58),
however, that a higher percentage of articaine is metabolized in the blood than in the
liver. Van Oss (56) found protein binding of articaine in patients varied between 50%
and 70% and protein binding of the metabolite articainic acid varied between 60% and
90%. Isen stated that 90% to 95% of articaine is metabolized in the blood and only 5% to
10% is broken down by the microsomal P450 enzyme system in the liver (51). The halflife of articaine has been reported to be as low as 20 minutes (56) in comparison to the
half-life of lidocaine, which is approximately 90 minutes (59). Oertel and Rahn (58)
studied the clinical pharmacokinetics of articaine and also found the elimination half-life
to be 20 minutes. Jakobs et al. (60) evaluated the pharmokinetics of both 2% and 4%
articaine in children and found the plasma half-life of the 2% solution to be 18.5 minutes
and the 4% solution to have a half-life of 23.6 minutes. Muller et al. (61) studied the
pharmacokinetics of articaine in mandibular nerve block anesthesia using 2 mL of 4%
17
articaine with 1:200,000 epinephrine in 10 awake patients and 10 patients during general
anesthesia. Blood samples from peripheral veins showed a half-life of approximately 20
minutes after conduction of anesthesia. Muller concluded that compared to other local
anesthetics whose plasma half-life may vary between 1 hour and 3.6 hours, the 20 minute
value found for articaine was very low. The reason for such a low value is explained, in
part, due to its structure, with the ester group metabolized by plasma esterases. This is a
rapid process compared with the microsomal P450 enzyme system of the liver (51).
Articaine is eliminated via the kidneys (54). Van Oss et al. (56) found 2-5% of
articaine is excreted unchanged, 30-70% is excreted as articainic acid, and 4-15% as
articainic acid glucoronide. Renal clearance of articaine varies between 12 and 28
ml/min-1 and that of articainic acid varies between 84 and 160 mL/min-1.” (26)
Articaine: Safety
“Both articaine and lidocaine have a maximum safe dose of 7 mg/kg for
uncompromised patients. Both articaine and lidocaine have the same maximum
milligram dose of 500 mg for an average, healthy, 70 kg adult (62). Every 1.8 mL
cartridge of 4% articaine contains twice the amount of drug (72 mg) as a 1.8 mL cartridge
of 2% lidocaine (36 mg). The maximum number of cartridges of articaine that a patient
can be safely given would therefore be almost half the number of cartridges that the same
patient could receive if lidocaine were selected. At a body weight of 70 kg, an average
adult’s maximum lidocaine dose would be 490 mg of either articaine or lidocaine, which
translates into 13.6 cartridges of 2% lidocaine with epinephrine or 6.8 cartridges of 4%
articaine with epinephrine (62).
18
Sodium metabisulfate (63) is a sulfite in both lidocaine and articaine preparations
that may cause allergic-type reactions including anaphylactic symptoms and lifethreatening or less severe asthmatic episodes in certain susceptible people. The overall
prevalence of sulfite sensitivity in the general population is unknown but is seen more
frequently in asthmatic than non-asthmatic people.
The rapid break-down of articaine and the apparent inactivity of the metabolites
imply that it is perhaps a safer anesthetic than other anesthetics (including lidocaine)
currently available.”(23)
“In his editorial on articaine, Weaver (62) noted the excellent safety record for
articaine worldwide. Weaver stated that although lidocaine and other amides have been
implicated in a number of pediatric deaths, there are few reports of overdose mortalities
attributed to articaine. He raised the question: ‘is articaine inherently safer despite its
higher concentration?’ Weaver attributed the safety to possible underreporting of
overdose reactions and acknowledged that the mg/kg maximum dose for articaine may be
very conservative. In addition, Weaver also stated that dentists in countries where
articaine is commonly used may meticulously calculate the maximum recommended
doses for each patient to avoid overdose. Perhaps these dentists avoid high blood levels
of articaine by spreading out their injections over the entire appointment or these dentists
have better training and are better able to recognize and appropriately treat overdose
reactions. Weaver stated that articaine is safe and effective when used in appropriate
doses for dental patients.
Malamed et al. (64) investigated the safety of articaine compared to lidocaine in
adult dental patients. A total of 1,325 patients undergoing general dental procedures
19
were evaluated for adverse effects of the injected anesthetic solutions. The subjects were
randomized in a 2:1 ratio to maximize gathering more information about articaine.
Subjects received comparable volumes of articaine and lidocaine for both simple and
complex procedures, but higher mg/kg doses of articaine in both types of procedures due
to the higher concentration of articaine at 4% versus lidocaine at 2%. Safety was
evaluated by measuring vital signs before administration, 1 and 5 minutes postadministration of the medication, and at the end of the procedure. Adverse events were
also elicited during telephone call follow-up both 24 hours and 7 days after the
procedure. Results showed that the overall incidence of adverse events in the combined
studies to be 22% (191 of 882 patients) for the articaine group and 20% (89 of 443
patients) for the lidocaine group. One patient in the lidocaine group had to discontinue
the study due to chest pain and dizziness. No deaths were reported associated with either
anesthetic in this study. In the articaine group the most common adverse event was post
procedural pain (13%). Other reported adverse events using articaine included headache
(4%), facial edema (1%), infection (1%), gingivitis and paresthesia (1%). The most
commonly reported adverse events which were considered by the investigator to be drugrelated were paresthesia (0.9%), hypesthesia (0.7%), headache (0.55%), infection
(0.45%), rash (0.3%), and pain (0.3%). Heart rate and respiratory rates increased slightly
at 1 and 5 minutes, however, by post procedural times had decreased slightly below the
baseline values. Lidocaine had similar adverse events to those reported for articaine.
However, one case of mouth infection and one case of mouth ulceration rated at severe
intensity were reported from the articaine group. Malamed et al. concluded that articaine
20
4% with 1:100,000 epinephrine has a low risk of toxicity that appeared comparable to
other local anesthetics.”(23)
“Simon et al. (65) investigated differences between three anesthetics during
intravenous regional anesthesia in a double-blind, randomized clinical trial. Thirty
patients received either 0.5% articaine, 0.5% lidocaine, or 0.5% prilocaine via an 18gauge cannula placed into a suitable vein on the dorsum of the hand. Differences in side
effects and maximum drug concentrations were evaluated. The plasma drug
concentration was evaluated by high performance liquid chromatography. The peak
levels were found immediately after release of the tourniquet and gradually decreased
over time. The maximum concentrations were 1.85, 8.5, and 4.4 µg/ml for articaine,
lidocaine, and prilocaine, respectively. Articaine had the lowest peak concentration of
the three local anesthetics when used for intravenous regional anesthesia. The authors
speculate that the low plasma levels of articaine may be a result of its hydrolysis by
plasma esterase. In addition, no signs of local anesthetic toxicity of the cardiovascular or
central nervous system were seen when using articaine.
Hidding and Khoury (59) evaluated the safety of four commonly used anesthetics
in dentistry in a prospective, randomized, double-blind study. Subjects were
administered a mandibular nerve block with either 4% articaine with 1:100:000
epinephrine, 4% articaine with 1:200,000 epinephrine, 3% prilocaine with 1:1,850,000
felypressin, or 2% lidocaine with 1:100,000 epinephrine. Differences in blood pressure
and heart rate were compared. In 1,518 adult subjects, 2.6% of all subjects had an
increase in blood pressure equal to or greater than 20 mm Hg and 7.4% had a drop in
blood pressure equal to or greater than 20 mm Hg two minutes after injection. Increases
21
in heart rate of more than 20 beats per minute were observed in 4.2% of the subjects.
However, there were no significant differences among the four groups with respect to
changes in blood pressure or heart rate. One subject who received articaine 4% with
1:100,000 epinephrine experienced diplopia after injection. It resolved after 15 minutes.
Daublander et al.(66) investigated the incidence of complications associated with
local anesthetic use in dentistry. In the study, 2,731 patients receiving local dental
anesthesia were evaluated for complications associated with the administration of
articaine in an oral surgery clinic in Germany. The overall incidence of complications
was 4.5%, with the incidence higher in at-risk patients (5.7%) than non-risk patients
(3.5%). Articaine was reported to have been administered in over 90% of all local
anesthetic injections in Germany with a low incidence of complications. Severe
complications, including seizure and bronchospasm, occurred in only two cases, a 0.07%
incidence. The most frequently observed complications were dizziness, tachycardia,
agitation, nausea, and tremor, which were transient in nature and did not require
treatment.”(23)
“Moller (67) examined the cardioelectrophysiologic effects of articaine in
comparison to both bupivacaine and lidocaine in isolated rabbit heart preparations. The
effects of the three local anesthetics on action potentials from the Purkinje fiber and
ventricular muscle tissues were determined. Moller found that articaine, at ten times its
observed clinical blood concentration, was significantly less cardiodepressive than
bupivacaine at only five times its observed clinical blood concentration.
Articaine has been shown to be safe in children over 4 years of age. Articaine is
not recommended for children under the age of 4 because, according to the articaine
22
product monograph (63), no data exists to support its use. However, recent clinical
studies have shown articaine to be safe even in children under 4 years of age(60, 68).
Wright et al. (69) evaluated the use of articaine administered in children under 4
years old using in a retrospective survey of dental records from 2 pediatric dental offices
in Ontario, Canada. Two hundred and eleven children (59 receiving preoperative sedation
with chloral hydrate, hydroxyzine hydrochloride, and nitrous-oxide) from 12 to 48
months of age whom received articaine as a maxillary infiltration or mandibular block
were evaluated for any observed or reported adverse reactions. All 211 patients received
a total of 240 doses of articaine without any reported adverse effects.”(23)
“Jakobs et al. (60) measured the levels of articaine in the serum of children 3 to
12 years old at multiple time intervals after administration of the drug. The study was
carried out on a total of 27 children undergoing general anesthesia. Three mL venous
blood samples were gathered before local anesthesia and then again after 2, 5, 10, and 20
minutes after infiltration with either 2% articaine with 1:200,000 epinephrine or 4%
articaine with 1:200,000 epinephrine. Jakobs observed that the pharmacokinetic profile
of articaine was similar to that observed in adults. The maximum serum concentration in
the children was 1,060 micrograms/ml for the 2% solution and 1,382 micrograms/mL for
the 4% group. These values are comparable to Kirsch et al. (70), who investigated
maximum serum concentrations in adults with results approximating 1,170 mg/mL after
injection of 240 mg of articaine. The t-max values were 7.44 minutes in the 2% group
and 7.78 in the 4% group. These values were comparable with investigations of
pharmocokinetic characteristics of articaine in adults. Muller (61) found average t max
values to vary between 16.9 and 17.7 minutes in adults. Jakobs (60) claims that the t23
max values in children are distinctly earlier and the plasma clearance is distinctly
increased in comparison to that found in adults. Jakobs found no particular adverse
events, side-effects, or untoward incidents. Jakobs concluded that there is no reason to
adjust the mg/kg dose limit for children as compared to adults. However, it is important
to remember that for a small child (15 kg or approximately 30 pounds), the toxic dose can
be reached with less than two cartridges of a 4% articaine solution (51, 71).
Malamed and Gagnon (71) investigated the safety of articaine compared to
lidocaine in pediatric dental patients. Subjects aged 4 to 13 years old undergoing general
dental procedures were evaluated for adverse effects of the injected anesthetic solutions.
Fifty subjects were randomized in a 2.5:1 ratio to maximize the gathering of more
information about articaine. Subjects received comparable volumes of articaine and
lidocaine for both simple and complex procedures, but higher mg/kg doses of articaine in
both types of procedures due to the higher concentration of articaine at 4% versus
lidocaine being 2%. Safety was evaluated by measuring vital signs before administration
and 1 and 5 minutes post-administration of the medication and at the end of the
procedure. Adverse events were also elicited during telephone call follow-up both 24
hours and 7 days after the procedure. Results showed at least one minor adverse event
was reported by 8% of the articaine subjects and by 10% of lidocaine subjects. The
adverse events noted were post-procedural pain (2%), headache (2%), injection site pain
(2%), and accidental injury/lip bite (2%). There were no serious adverse events and no
deaths in any children. One patient received more than the recommended maximum
dosage of 7.0 mg/kg of articaine and reported no adverse effects. Mean supine blood
pressure values increased slightly from baseline after administration of articaine but the
24
changes were not clinically significant and were not associated with any adverse events.
Malamed et al. concluded that 4% articaine with 1:100,000 epinephrine was safe when
administered by injection in children at least 4 years of age.”(23)
Adewumi et al. (68) found that 40% of children (ages 2 to 14) receiving routine
restorative care with 4% articaine solution for restorative care reported prolonged
paresthesia at three hours post injection and 11% at five hours post injection. At three
hours post injection, fourteen percent of patients reported soft-tissue injury, most
commonly involving the lip and with children under the age of seven. Overall, prolonged
numbness from articaine appears to be the most frequently reported adverse effect,
occurring primarily in children under the age of seven. The authors suggest that parents
should be informed properly about post operative care.
“Malamed et al. (71) cautioned the use of articaine in patients with hepatic disease
and significant impairments in cardiovascular function since amide-type local anesthetics
undergo biotransformation in the liver and possess myocardial depressant properties.
Oertel and Rahn (72) investigated the pharmocokinetics of articaine in elderly
patients. The premise investigated was that with increasing age comes physiologic
changes that could affect the pharmaocokinetics of local anesthetics. Submucosal
infiltration of two different dosages of 4% articaine without epinephrine was compared
between healthy young and healthy elderly adults. The clearance and volume of
distribution of articaine after infiltration was significantly lower in the elderly subjects
compared to the young. However, the area under the serum concentration-time curve and
maximum drug concentration did not differ significantly with age. Likewise, no changes
in terminal half-life and time to reach maximum serum concentration were observed.
25
The values of the metabolite, articainic acid, were also similar in the young and elderly
subjects. The authors concluded that no change of dosage of articaine in elderly patients
should be necessary.”(26)
“Articaine has been classified by the Food and Drug Administration as a
pregnancy category C drug. There have been no adequate and well-controlled studies in
pregnant women. Leuschner et al. (73) studied the toxicological profile of articaine. The
toxicity of 4% articaine with 1:100,000 epinephrine was examined in vitro and in vivo for
repeated dose toxicity, reproduction toxicity, mutagenic potential, and local tolerance.
Rats and dogs were subjected to repeated subcutaneous administration of articaine and
none of the animals demonstrated pathomorphological systemic changes even at high
enough doses to be considered toxic. The no-effect level was found to be 25 mg/kg/day
for the rat and 40 mg/kg/day for the dog. Reproduction studies were evaluated in rats and
rabbits at doses ten times the maximum recommended human dose of 7 mg/kg/day and
showed no evidence of harm to the fetus or to other related aspects of reproduction. This
was true even when the doses were toxic to the parental animals. The mutagenicity
studies also showed no mutagenic potential up to cytotoxic concentrations or up to the
maximum tolerated dose levels. The authors concluded the local tolerance of articaine
was very good. The data indicated that articaine did not possess any relevant side effects
or toxicity and can be considered a safe local anesthetic. Animal reproduction studies are
not always predicative of human response (63). Therefore, articaine should be used
during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Likewise, it is not known if articaine is excreted in human milk. Because many drugs are
26
excreted in human milk, caution should be exercised when articaine is administered to
nursing women.”(26)
“Articaine, like prilocaine, at very high doses is capable of producing
methemoglobinimea (51). Methemoglobinimea has been observed, although rarely,
when it is administered intravenously for regional anesthesia (31). However, when used
within the recommended dosages for dental anesthesia, the occurrence of this side effect
is unlikely and there have been no cases reported following administration for dental
anesthesia (51).
Penarrocha-Diago (74) reported on fourteen cases of ophthalmologic
complications after intraoral anesthesia of the posterior superior alveolar nerve. The
most common symptoms encountered included diplopia, mydriasis, palpebral ptosis, and
abduction difficulties of the affected eye. In all cases, the symptoms were immediate,
occurring within minutes after injection of the anesthetic. All cases resolved without
sequelae after the anesthesia subsided. The mechanism for the observed side-effects
included diffusion of the anesthetic through the anatomic space near the orbit.
Articaine has a low risk of causing paresthesia following a mandibular block.
However, the use of a 4% solution of both articaine and prilocaine has been found to be
associated with a significantly higher risk of paresthesia following a mandibular block
than using a 2% lidocaine solution (51). The incidence is still extremely rare.”(26)
“Haas and Lennon (75) and Miller and Lennon (76) investigated the incidence of
local anesthetic-induced neuropathies following administration with different types of
local anesthetics. These two studies used a retrospective method to review cases from
different time periods in Ontario, Canada to determine if articaine and prilocaine were
27
significantly more likely to be associated with neuropathies. The incidence of reported
cases of neuropathies from 1994-1998 (76) was one in 765,000 injections or 1.3
injections per million. A high level of statistical significance was observed for the
incidence of post-injection paresthesia associated with articaine and prilocaine compared
to other agents. The incidence of neuropathies associated with articaine and prilocaine
was approximately five times that found with either lidocaine or mepivacaine. The
neuropathies observed in all cases involved the lip and/or tongue. These results are
consistent with other previously published data (75) and suggest that articaine may have
the potential for mild neurotoxicity.
Malamed et al. (64) also obtained data regarding paresthesia after injection of
articaine based on Haas and Lennon's report (75). A total of 1,325 patients undergoing
general dental procedures were evaluated for adverse effects of the injected anesthetic
solutions. The subjects were randomized in a 2:1 ratio to maximize the gathering of more
information about articaine. The total number of subjects who reported paresthesia 4 to 8
days after the procedure was 8 (1%) for the articaine group and 5 (1%) for the lidocaine
group. However in 4 cases of the articaine group and 1 case of the lidocaine group, the
symptoms did not begin on the day of the study. This suggests that the paresthesias were
caused by the procedure rather than by the anesthetic itself (64). In all cases the
paresthesia ultimately resolved.” (26)
“A few reported cases of allergic reactions to articaine have been reported.
Malanin and Kalimo (77) presented a case of an acute cutaneous reaction after
administration of local anesthesia using 4% articaine with 1:200,000 epinephrine. The
patient was a 38 year old female in good health with no history of atopy. During the
28
year, she had visited the dentist on several occasions and was administered articaine local
anesthetic without any adverse reaction. On one particular occasion, however, she was
administered an infiltration of 1.7 ml articaine and after 15 minutes she experienced
itching on her skin and redness and papules developed on her chest, abdomen, axillae,
hands, and groin. The rash disappeared after a few hours. Two weeks later 2% lidocaine
with and without epinephrine were tested in a similar manner and no reaction was seen.
Malanin and Kalimo explain the allergic reaction as a complement-mediated mechanism
via liberation of anaphylatoxins and degranulation of mast cells which cause the
inflammation. Klein et al. (78) reported a case of a slow anaphylactoid reaction in a
patient to lidocaine whom was able to tolerate articaine without reaction. Likewise, the
patient in the Malainin and Kalimo case had no crossreactivity with lidocaine. They
concluded that although both local anesthetics are of the amide type, they both have
marked differences in their chemical structures.
Warrington (79) reported on a case of articaine hypersensitivity. A 35 year old
woman developed generalized giant hives about 5 minutes after receiving an injection of
articaine by her local dentist. The patient went to a nearby clinic and received 50 mg of
intramuscular diphenhydramine and her symptoms resolved after 1 to 2 hours. She had
no angioedema or breathing problems. She had most recently received articaine at the
dentist 3 years earlier without previous problems. Warrington stated that when type I
hypersensitivity is present, there is extensive cross-reactivity among the local anesthetics
of the amide group. Warrington concluded that the subject’s history and positive skin
29
test alone strongly suggest that she did have an immediate hypersensitivity reaction to
articaine and the reaction exhibited crossreactivity with other amide local anesthetics.”
(26)
“A review by Haas discussed the epidemiological evidence regarding incidence of
paresthesia with articaine (80). Paresthesia is considered irreversible when resolution
does not take place within eight weeks. Haas & Lennon published the first study to
suggest the possibility that articaine is more highly associated with paresthesia than other
local anesthetics(81). Since then, other studies have shown incident rates up to twentyfold higher than lidocaine, usually associated with the lingual nerve (82). Haas attributes
the increased incidence not to the drug itself, but to the higher concentrations of
anesthetic. Articaine is marketed as a 4% solution, which means that the concentration of
the drug is 40 mg/mL. This is twice the concentration of lidocaine, which is most
frequently used as a 2% solution. The author recommends that articaine and other highconcentration anesthetics such as prilocaine should be avoided for mandibular and lingual
blocks.” (27)
Articaine: Efficacy, Onset Time and Duration for Mandibular
Infiltration Injections
“Articaine has a reputation for providing improved local anesthetic efficacy. The
available literature indicates that articaine is at least comparable to other existing local
anesthetics (51). Due to the inherent chemical differences between articaine and the
other amide anesthetics, many case reports and empirical evidence have claimed more
profound anesthesia and longer duration of activity when using articaine. Articaine is the
30
only amide local anesthetic that contains a thiophene ring. This renders the molecule
more lipid soluble and therefore, hypothetically, better able to cross lipid barriers (for
example, the nerve membranes) (51) and better able to diffuse through soft tissue and
bone than other local anesthetics, including lidocaine (58).
Dudkiewicz (83) evaluated the effectiveness of articaine during mandibular
infiltrations in children. 50 children with a mean age of 7 years old, ranging from 4 to 10
years, were evaluated in the study. Two clinicians performed 84 treatments in the fifty
children. Four percent articaine with 1:200,000 epinephrine was injected into the mucobuccal fold corresponding to the tooth/teeth being treated. One and two tenths milliliter
of solution was administered for teeth with a single root, while 2.7 mL of solution was
administered for teeth with multiple roots. Anesthesia was successful in all cases and no
reinjection was performed. There were, however, a few instances where a child
complained of pain at the beginning of the operative procedure. In such cases an
additional 5 minute waiting period was allowed to elapse and anesthesia was then found
to be successful. The authors claim that articaine was able to diffuse through the bone to
the lingual side of the tooth because clamp placement and stainless steel crown
preparations were performed on the lingual surface without any problems. Without
lingual perfusion of the anesthetic, these procedures would have been painful and
impossible for the children. The authors attribute the ability of articaine to diffuse to the
lingual tissue because of its molecular configuration, the lipophilic thiophene ring, and
because of the high partition coefficient of articaine found during Casanovas’ study.
Casanovas et al. (84) evaluated the partition coefficient of four local dental anesthetics.
Articaine was shown to possess a superior partition coefficient (123.0) compared to
31
lidocaine (10.0), prilocaine (6.9), and bupivacaine (83.2). According to Dudkiewicz (83),
the superior partition coefficient of articaine helps provide physiochemical evidence to
support the contention that articaine hydrochloride has better penetration and diffusion
compared to other local anesthetics. The author concluded that mandibular infiltration
using articaine hydrochloride in children with posterior primary teeth was the technique
of choice for successful anesthesia. Efficacy was the focus of this investigation. Onset
time and duration was not studied.
Wright et al. (85) determined the effectiveness of infiltration anesthesia in
mandibular primary molars. Sixty-six subjects requiring restorative treatment on
mandibular molars, ranging in age from 42 months to 6 years old, were anesthetized by
buccal infiltration anesthesia. Three anesthetics were evaluated: 4% articaine, 4%
prilocaine, and 2% mepivacaine all with 1:200,000 epinephrine. Ten minutes after
infiltration, a rubber dam was placed and drilling was initiated. The authors concluded
that articaine was equivalent to prilocaine and mepivacaine for infiltration anesthesia of
primary mandibular molars. Onset time and duration was not investigated.”(23)
“Haas et al. (20) investigated the claim that anesthesia of mandibular pulpal and
lingual soft tissue, as well as maxillary palatal soft tissue, results following buccal
infiltration of the articaine local anesthetic using a double-blind, randomized clinical trial
model. The authors’ aim was to scientifically test these claims by comparing 1.5 mL 4%
articaine HCl with 1:200,000 epinephrine to 1.5 mL 4% prilocaine HCl with 1:200,000
epinephrine. Nineteen healthy adult volunteers had the two anesthetic solutions
deposited by infiltration next to the second molar and next to the contralateral second
molar. Pulpal anesthesia was compared by electric pulp tester readings for a period of 25
32
minutes. Additionally differences related to soft tissue anesthesia were also analyzed.
Lingual and palatal tissues were not expected to be anesthetized with a buccal infiltration
alone. They found that articaine was able to penetrate deep into the tissue to result in
lingual soft tissue anesthesia, at least in some subjects. When second molars were
anesthetized by buccal infiltrations, articaine produced more clinically profound pulpal
anesthesia compared to prilocaine (63% versus 53%), more clinically profound
mandibular lingual tissue anesthesia (50% versus 37%), and more clinically profound
palatal tissue anesthesia (40% versus 30%). Articaine was also more effective than
prilocaine in the canine region in regard to pulpal anesthesia (50% versus 37%) and
mandibular lingual soft tissue anesthesia. Prilocaine, however, was more effective than
articaine in the palatal soft tissue anesthesia in the region of the maxillary canines.
However, these results showed no statistically significant difference between articaine
and prilocaine as determined by the chi-square analysis. Articaine onset time and
duration was not studied.
Haas et al. (16) utilized the same methods as used in his original investigation in
another double-blind randomized trial. Again differences between 1.5 mL 4% articaine
hydrochloride with 1:200,000 epinephrine and 1.5 mL 4% prilocaine hydrochloride with
1:200,000 epinephrine were compared. Twenty healthy adult volunteers had the
anesthetic solutions infiltrated next to the canine and contralateral canine. Efficacy was
again evaluated by electric pulp tester readings for 25 minutes. Additionally, differences
related to soft tissue anesthesia were also analyzed. Lingual tissues were not expected to
be anesthetized with use of a buccal infiltration alone. Results for mandibular canines
showed that articaine achieved successful pulpal anesthesia in 65% of the subjects
33
compared to 50% for prilocaine. Lingual tissues achieved anesthesia 10% of the time
with articaine compared to 5% with prilocaine. These differences, however, were again
not found to be statistically significant as determined by the chi-square analysis. Onset
time and duration were not investigated.”(23)
“Hintze et al. (86) have compared a 2% and 4% solution of articaine both with a
1:200,000 epinephrine concentration. Local infiltration injections were administered for
tooth extractions. The duration of anesthesia was significantly longer for the 4%
solution, but the 4% solution was not considered superior in local anesthetic effect.
Therefore a 2% solution can be considered for tooth extractions.” (27)
“Malamed et al. (54) studied the efficacy of articaine when comparing 4%
articaine with 1:100,000 epinephrine to 2% lidocaine with 1:100,000 epinephrine in three
identical randomized, double-blind, multicenter clinical trials. Subjects ranged from ages
4 to 80 years and were injected with either 4% articaine with 1:100,000 or 2% lidocaine
with 1:100,000 (by either submucosal infiltration, inferior alveolar nerve block, or both)
during both simple and complex dental procedures. A total of 1,325 subjects were
randomized in a 2:1 ratio to maximize gathering more information about articaine.
Subjects received comparable volumes of articaine and lidocaine for both simple and
complex procedures, but higher mg/kg doses of articaine in both types of procedures due
to the higher concentration of articaine at 4% versus lidocaine at 2%. Time of onset and
duration of anesthesia for articaine was considered comparable to lidocaine. Efficacy
was evaluated on a gross scale immediately following the procedure by having both the
subject and the investigator rate the pain experienced by the subject during the procedure
using a visual analog scale (VAS). All VAS scores were considered very low, with mean
34
pain scores of less than 1.0. In all cases, the mean score for articaine was lower (less
pain) than for the lidocaine group. However, Malamed et al. found no statistical
differences between the two anesthetic solutions tested. They concluded that 4%
articaine with 1:100,000 epinephrine was effective and well-tolerated in all 882 subjects.
Malamed and Gagnon (71) compared the difference in efficacy of articaine versus
lidocaine in pediatric dental patients. The study did not specify the type of injection –
whether block, infiltration, or both. Subjects aged 4 to 13 years old undergoing general
dental procedures were evaluated for onset time and efficacy of the injected anesthetic
solutions. Fifty subjects were randomized in a 2.5:1 ratio to maximize the gathering of
more information about articaine. Subjects received comparable volumes of articaine and
lidocaine for both simple and complex procedures, but higher mg/kg doses of articaine in
both types of procedures due to the higher concentration of articaine at 4% versus
lidocaine at 2%. Efficacy was evaluated on a gross scale immediately following the
procedure by having both the subject and the investigator rate the pain experienced by the
subject during the procedure using a 10 cm visual analog scale. Results showed VAS
scores were slightly higher for both articaine and lidocaine in children than for adult
groups. Time of onset and duration of anesthesia were considered comparable to other
commercially available local anesthetics. All VAS scores were considered very low and
no statistically significant differences were noted between articaine and lidocaine. They
concluded that 4% articaine with 1:100,000 epinephrine was effective when administered
by injection in children at least 4 years of age.” (23)
“Haase et al. (19) compared the difference in efficacy of articaine and lidocaine
when given as a mandibular buccal infiltration in normal, asymptomatic vital teeth. The
35
study was a prospective, randomized, double-blind, crossover study to compare the
degree of pulpal anesthesia obtained with 4% articaine with 1:100,000 epinephrine and
2% lidocaine with 1:100,000 epinephrine in buccal infiltrations of the mandibular first
molar following an inferior alveolar nerve block administered with 4% articaine with
1:100,000 epinephrine. Anesthetic success as well as pain of injection was recorded.
There were no statistically significant differences between solutions with regard to pain
of injection. For postoperative pain, there were no statistically significant differences
between lidocaine and articaine. The first molar showed a statistically significant
difference for the articaine solution when compared to the lidocaine solution (p=0.0075)
when evaluating anesthetic success, as defined by continuously sustaining an 80/80
reading on an electric pulp tester for 60 minutes.” (23)
Haase et al. (19) also studied duration and onset of anesthesia from the
supplemental infiltration injections of articaine and lidocaine. The authors found the
duration of pulpal anesthesia of the mandibular first molar using an IAN block and buccal
infiltration injection with 4% articaine with 1:100,000 epinephrine to be around 37
minutes. When the buccal infiltration injection was administered using 2% lidocaine
with 1:100,000 epinephrine, the duration decreased to 28 minutes, with a more
pronounced decline after 46 minutes. For both the articaine and lidocaine solutions,
onset time was noted as a gradual increase in pulpal anesthesia, either related to the effect
of the infiltrations overcoming failure, or the effect of slow onset of anesthesia from the
initial inferior alveolar nerve block.
“A recent study by Kanaa et al. (18) compared the anesthesia produced by one
cartridge of 2% lidocaine with 1:100,000 epinephrine to 4% articaine with 1:100,000
36
epinephrine for mandibular infiltration injections. Success was defined as having two
consecutive negative readings with the electric pulp tester at any time during the 30minute testing period. Articaine had 64.5% success while lidocaine had only 38.7%
success in producing mandibular first molar anesthesia. Meechan and Kanaa et al. (22)
compared the results from the mandibular buccal infiltration using lidocaine to a
combined mandibular and lingual infiltration of the mandibular first molar using
lidocaine. One cartridge was administered, half at the buccal site and half at the lingual
site. Success was lower with the combined infiltration (32.3% vs. 38.7%), but this
difference was not significant.”(19)
Robertson et al. (14, 25) compared articaine and lidocaine in a mandibular
posterior buccal infiltration injection in normal, asymptomatic vital teeth. The study was
a prospective, randomized, double-blind study to compare the anesthetic efficacy of 1.8
mL of 4% articaine with 1:100,000 epinephrine and 1.8 mL of 2% lidocaine with
1:100,000 epinephrine (control) in buccal infiltration injections of the mandibular first
molar. Anesthetic success (obtaining two consecutive 80 readings) for articaine and
lidocaine were, respectively, as follows: 75% and 45% of the second molars; 87% and
57% for the first molars; 92% and 67% of the second premolars; and 86% and 61% of the
first premolars. Statistical analysis showed a significant difference (p<0.05) between the
solutions with each tooth type for success. The results revealed articaine was
significantly better than lidocaine in achieving pulpal anesthesia with a buccal infiltration
of the mandibular first molar. Also, Robertson demonstrated a faster onset time with an
articaine solution, when compared to a lidocaine solution, when used for buccal
infiltration injections in mandibular posterior teeth. The onset of pulpal anesthesia was
37
approximately 4 to 5 minutes for articaine and 6 to 11 minutes for lidocaine, depending
upon the tooth tested.
Pabst et al. (87) conducted a prospective, randomized, single-blind, crossover
study comparing the degree of pulpal anesthesia obtained with two sets of mandibular
first molar buccal infiltrations. The infiltrations were given in two separate
appointments to 86 adult subjects, as follows: an initial infiltration of a cartridge of 4%
articaine with 1:100,000 epinephrine plus a repeated infiltration of the same anesthetic
and dose given 25 minutes following the initial infiltration and an initial infiltration of a
cartridge of 4% articaine with 1:100,000 epinephrine plus a mock repeated infiltration
given 25 minutes following the initial infiltration. “The authors used an electric pulp
tester to test the first molar for anesthesia in 3-minute cycles for 120 minutes after the
injection. The repeated infiltration significantly improved pulpal anesthesia from 28
minutes through 118 minutes in the mandibular first molar. A repeated infiltration of a
cartridge of 4% articaine with 1:100,000 epinephrine given 25 minutes after an initial
infiltration of the same amount and dose of anesthesia significantly improved the
duration of pulpal anesthesia when compared to only an initial buccal infiltration, in the
mandibular first molar. For both initial infiltrations, anesthetic success ranged from 64
to 69%. There was no significant difference between the initial infiltration
injections.”(87) Onset time for the single buccal infiltration and the repeated buccal
infiltration ranged from 5.4 to 6.2 minutes (87).
“Meechan et al. (88) compared a buccal infiltration of 1.8 mL 4% articaine with
1:100,000 epinephrine to a buccal plus lingual infiltration of the same solution (0.9 mL
buccal and 0.9 mL lingual) in achieving pulpal anesthesia in asymptomatic healthy
38
mandibular first molar teeth. The data was compared to the efficacy of an inferior
alveolar nerve block using 2% lidocaine with 1:80,000 epinephrine. Anesthetic success
was determined using an electric pulp tester. Buccal and buccal plus lingual infiltrations
of articaine with epinephrine did not differ in efficacy in obtaining pulpal anesthesia for
mandibular first molars. The results for the infiltrations were similar to that of an IAN
block using lidocaine with epinephrine. Patients were asked to report subjective tooth
numbness. Numbness was more common after an IAN block than a buccal infiltration.
Onset time and duration was not studied.
Rosenberg et al. (89) conducted a randomized, double-blind clinical trial to
compare the efficacy of 4% articaine with 1:100,000 epinephrine and 2% lidocaine with
1:100,000 epinephrine when used as a buccal infiltration supplemental injection in
irreversible pulpitis patients. The study consisted of 48 patients with 22 maxillary and 26
mandibular teeth. Twelve maxillary teeth received supplemental injections of 4%
articaine with 1:100,000 epinephrine, whereas ten teeth received supplemental injections
of 2% lidocaine with 1:100,000 epinephrine. In the mandible, 13 teeth received 4%
articaine with 1:100,000 epinephrine as a supplemental injection and 13 teeth received
2% lidocaine with 1:100,000 epinephrine as a supplemental injection. VAS scores
evaluated the patient’s response to pain after a supplemental injection. There was no
significant difference in the VAS pain score between both solutions when given as
supplemental anesthetic. Supplemental anesthetic efficacy was not evaluated. Onset
time and duration was not evaluated.”(23)
“Rahn et al. (90) evaluated 2% articaine without epinephrine with 4% articaine
with 1:200,000 epinephrine in a prospective, randomized study to evaluate whether the
39
solution without epinephrine is suitable for dental surgery. Results showed the 2%
solution was less effective than the 4% solution. However, in many cases, the 2%
solution was sufficient for dental treatment, including surgery. The duration (33 minutes)
of the 2% solution was, however, shorter than the 4% solution (43 minutes).
Cowan et al. (91) studied four parameters related to articaine including onset time
and duration. Onset time was based on the subjects’ experience of pain during drilling.
Cowan et al. determined the onset time of anesthesia of 4% articaine with 1:200,000
epinephrine to be 1.5 to 1.8 minutes for maxillary infiltration and 1.4 to 3.6 minutes for
inferior alveolar nerve block. Onset time for 2% lidocaine with 1:100,000 epinephrine
was determined to be 1.3 minutes for mandibular infiltration and mental block, with a
duration of 3 hours. The onset time for 4% articaine with 1:200,000 epinephrine was
found to be 1.8 minutes for mandibular infiltration and mental block, with a duration of
2.25 hours. Cowan found that the articaine solution was slower in terms of onset than the
lidocaine solution, suggesting lower potency. The duration of soft tissue anesthesia when
using articaine was 2.25 hours for maxillary infiltration and approximately 4 hours for
mandibular nerve block.” (26)
MANDIBULAR ANESTHESIA:
Articaine for Inferior Alveolar Nerve Block
“The most common injection for obtaining mandibular anesthesia is the inferior
alveolar nerve block. The traditional method for determining the success of the block is
lip numbness, which occurs within five to seven minutes. Studies confer that this clinical
sign determines that the anesthetic blocked the soft tissues of the lip, but pulpal
40
anesthesia may not have beeen obtained (1, 2, 92-98). A total missed block, soft tissue
nor pulpal anesthesia, occurs about 5% of the time. The onset of pulpal anesthesia, which
can be defined as two consecutive 80/80 readings on an electric pulp tester, occurs
usually within 10-15 minutes. In some patients, this will occur sooner and in about 1826% there will be a delay past fifteen minutes. In about 8%, onset can be delayed for 30
to 50 minutes (1, 43, 50, 92, 96-101). Successful mandibular pulpal anesthesia (numb
within fifteen minutes and continuously numb for one hour), tends to be more frequent in
molars (about 55%) and premolars (about 60%) and least in lateral incisors (around 31%)
(1, 43, 50, 92, 96-101). Therefore, not all patients will experience pulpal anesthesia after
what would appear to be a clinically successful (lip numbness) inferior alveolar nerve
block. Supplemental injections of anesthetic would be required.” (23)
“Malamed et al. (54) studied the efficacy of articaine when comparing 4%
articaine with 1:100,000 epinephrine to 2% lidocaine with 1:100,000 epinephrine in three
identical randomized, double-blind, multicenter clinical trials. Subjects ranged from ages
4 to 80 years and were injected with either 4% articaine with 1:100,000 or 2% lidocaine
with 1:100,000 (by either submucosal infiltration, inferior alveolar nerve block, or both)
during both simple and complex dental procedures. A total of 1,325 subjects were
randomized in a 2:1 ratio to maximize gathering more information about articaine.
Subjects received comparable volumes of articaine and lidocaine for both simple and
complex procedures, but higher mg/kg doses of articaine in both types of procedures due
to the higher concentration of articaine at 4% versus lidocaine at 2%. Time of onset and
duration of anesthesia for articaine was considered comparable to lidocaine. Efficacy
was evaluated on a gross scale immediately following the procedure by having both the
41
subject and the investigator rate the pain experienced by the subject during the procedure
using a visual analog scale (VAS). All VAS scores were considered very low, with mean
pain scores of less than 1.0. In all cases, the mean score for articaine was lower (less
pain) than for the lidocaine group. However, Malamed et al. found no statistical
differences between the two anesthetic solutions tested. They concluded that 4%
articaine with 1:100,000 epinephrine was effective and well-tolerated in all 882 subjects.”
(23)
“Ram et al. (102) assessed the reaction of children and anesthetic efficacy when
using 4% articaine with 1:200,000 epinephrine compared with 2% lidocaine with
1:100,000 epinephrine. Sixty-two pediatric patients who needed similar operative
procedures were randomly assigned to receive either articaine or lidocaine at their first or
second visit. Only twenty-two of the sixty-two patients were given IAN blocks at both
appointments, while the remaining forty were given maxillary infiltration injections at
both appointments. Modified Taddio's behavioural pain scale was used to evaluate pain
reaction during injection and treatment and the sensation after injection and treatment
was evaluated using the Wong-Baker FACES pain rating scale. No difference regarding
the efficacy of the anaesthesia or reaction to pain was observed.” (27)
“Mikesell et al. (103) compared the degree of pulpal anesthesia obtained with 4%
articaine with 1:100,000 epinephrine and 2% lidocaine with 1:100,000 epinephrine in
inferior alveolar nerve blocks. Anesthesia was considered successful when two
consecutive 80/80 readings were obtained with an electric pulp tester within 15 minutes
and the 80/80 reading was continuously sustained for 60 minutes. Successful pulpal
anesthesia ranged from 4 to 54% from the central incisor to the second molar with the
42
articaine solution. Using the lidocaine solution, successful pulpal anesthesia ranged from
2 to 48%. There was no significance (p>0.05) between the articaine and lidocaine
solutions.” (23)
“Claffey and co-authors (104) compared the anesthetic efficacy of 4% articaine
with 1:100,000 epinephrine to 2% lidocaine with 1:100,000 epinephrine for inferior
alveolar nerve blocks in patients experiencing irreversible pulpitis, in mandibular
posterior teeth. The success rate (none or mild pain upon endodontic access or initial
instrumentation) for the inferior alveolar nerve block using the articaine solution was
24% and for the lidocaine solution success was 23%. There was no significant difference
between the articaine and lidocaine solutions.” (19)
Tortamano et al. (105) compared the anesthetic efficacy of 4% articaine with
1:100,000 epinephrine with 2% lidocaine with 1:100,000 epinephrine for inferior alveolar
nerve blocks in patients with mandibular posterior irreversible pulpitis. Forty subjects
were divided into 2 groups of 20 patients. Each subject received inferior alveolar nerve
blocks with 3.6 mL of either 2% lidocaine with 1:100,000 epinephrine or 4% articaine
with 1:100,000 epinephrine. The anesthetic success was defined as pulpal access with no
pain, as reported by the subject. During the pulpectomy procedures, 7 patients (35%) of
the articaine group and 11 patients (55%) of the lidocaine group reported pain. There
was no statistically significant difference (p=0.20) in success between the two solutions.
In a prospective randomized double-blind study, Sherman et al. (106) compared
the anesthetic efficacy of 2% lidocaine with 1:100,000 epinephrine to 4% articaine with
1:100,000 epinephrine in maxillary and mandibular posterior teeth with symptoms of
irreversible pulpitis. Each of the 42 patients received either 1.7 mL of 4% articaine with
43
1:100,000 epinephrine or 1.8 mL of 2% lidocaine by using either a Gow-Gates inferior
alveolar nerve block or maxillary infiltration. If negative pulpal signs with cold stimuli
were achieved, the experimental tooth was accessed. After access was completed,
patients rated their discomfort on a modified VAS. Anesthesia was considered successful
if the subject’s tooth was accessed with a pain rating no greater than mild. Anesthetic
success, in both arches, was 87.5%. Four anesthetic failures were observed in the
mandibular arch and one in the maxillary arch, with no correlation observed between the
anesthetic solutions and failure.
MANDIBULAR INFILTRATION INJECTION:
Posterior Infiltration
“Wright et al. (85) investigated the effectiveness of infiltration anesthesia in
mandibular primary molars. Sixty-six subjects requiring restorative treatment on
mandibular molars, ranging from 42 months to 6 years old, were anesthetized by buccal
infiltration. Three anesthetics were evaluated: 4% articaine, 4% prilocaine, and 2%
mepivacaine, all with 1:200,000 epinephrine. Ten minutes after infiltration, a rubber dam
was placed and treatment was initiated. The authors concluded that articaine was
equivalent to prilocaine and mepivacaine for infiltration anesthesia of primary
mandibular molars.” (27)
“Haas et al. (16) investigated the claim that anesthesia of mandibular pulpal and
lingual soft tissue, as well as maxillary palatal soft tissue, results following buccal
infiltration of articaine. Using a double-blind, randomized clinical trial model, the
44
authors compared 1.5 mL 4% articaine with 1:200,000 epinephrine to 1.5 mL 4%
prilocaine with 1:200,000 epinephrine. Nineteen healthy adult volunteers had the two
anesthetic solutions deposited by infiltration buccal to the second molar and buccal to the
contralateral second molar. Pulpal anesthesia was assessed by electric pulp tester
readings for a period of 25 minutes. Differences related to soft tissue anesthesia were
also analyzed. Lingual and palatal tissues were not expected to be anesthetized with a
buccal infiltration alone. They found that articaine was able to penetrate deep into the
tissue to result in lingual soft tissue anesthesia, at least in some subjects. When second
molars were anesthetized by buccal infiltrations, articaine was superior to prilocaine at
producing more clinically profound pulpal anesthesia (63% versus 53%), mandibular
lingual tissue anesthesia (50% versus 37%), and palatal tissue anesthesia (40% versus
30%). These differences between articaine and prilocaine were not statistically
significant as determined by the chi-square analysis.” (23)
“A recent study by Kanaa et al. (18) compared the anesthesia produced by one
cartridge of 2% lidocaine with 1:100,000 epinephrine to 4% articaine with 1:100,000
epinephrine for mandibular infiltration injections. Success was defined as having two
consecutive negative readings with the electric pulp tester at any time during the 30minute testing period. Articaine had 64.5% success while lidocaine had only 38.7%
success in producing mandibular first molar anesthesia. Meechan and Kanaa et al. (22)
compared the results from the mandibular buccal infiltration using lidocaine to a
combined mandibular and lingual infiltration of the mandibular first molar using
lidocaine. One cartridge was administered, half at the buccal site and half at the lingual
45
site. Success was lower with the combined infiltration (32.3% vs. 38.7%), but this
difference was not significant.
Robertson et al. (14) conducted a prospective, randomized, double-blind study
comparing the anesthetic efficacy of an infiltration injection of a 4% articaine solution
with 1:100,000 epinephrine to a 2% lidocaine solution with 1:100,000 epinephrine in
mandibular posterior teeth. One cartridge of either solution was given near the apexes of
the first molar, then all four posterior teeth were pulp tested for a one hour period. The
articaine solution was superior (65% vs. 34%).” (19)
“Haase et al. (19) compared the difference in efficacy of articaine and lidocaine when
given as a mandibular buccal infiltration in patients with asymptomatic, vital mandibular
molars. The study compared the degree of pulpal anesthesia obtained with 4% articaine with
1:100,000 epinephrine and 2% lidocaine with 1:100,000 epinephrine in buccal infiltrations of
the mandibular first molar following an inferior alveolar nerve block administered with 4%
articaine with 1:100,000 epinephrine. Anesthetic success as well as pain of injection was
recorded. There were no statistically significant differences between solutions with regard to
pain of injection. For postoperative pain, there were no statistically significant differences
between lidocaine and articaine. The first molar had 65% anesthetic success with lidocaine
and 84% anesthetic success with articaine. The first molar showed a statistically significant
difference for the articaine solution when compared to the lidocaine solution (p=0.0075)
when evaluating anesthetic success, as defined by continuously sustaining an 80/80 reading
on an electric pulp tester for 60 minutes.” (23)
A study by Foster et al. (17), which compared the efficacy of buccal and lingual
infiltrations following an inferior alveolar nerve block using 2% lidocaine with 1:100,000
46
epinephrine, found neither a significant difference in anesthetic success between the
block plus buccal or lingual infiltrations, nor the block plus mock buccal infiltration and
mock lingual infiltration. Compared to Foster’s results, the higher success rates for each
respective posterior tooth, found by Haase et al., would indicate that the sampled
population had a significantly higher success rate with the inferior alveolar nerve block
(19). Following the inferior alveolar nerve block success, Foster et al. (17) found neither
the buccal or lingual supplemental injections of the lidocaine solution produced
significant increases in anesthetic success in the posterior mandible. The results support
the fact that lidocaine infiltration has some effect on pulpal anesthesia, while not
increasing success significantly.
“Jung et al. (107) compared the anesthetic efficacy of inferior alveolar nerve
blocks with that of buccal infiltrations in mandibular first molars. All subjects received a
standard IAN block or buccal infiltration of 1.7 mL of 4% articaine with 1:100,000
epinephrine on two appointments separated by at least one week. Pulpal anesthesia was
determined by using an electric pulp tester. Electric pulp testing was repeated at 5, 8, 11,
15, 20, 25, and 30 minutes after the injections. Anesthesia was considered successful if
the subject did not respond to the maximum output of the pulp tester at two or more
consecutive time points. Fifty-four percent of the buccal infiltration and 43% of the
inferior alveolar nerve block were successful, however the difference was not significant.
The onset for anesthesia was significantly faster with the buccal infiltration than the IAN
block.
Meechan et al. (88) compared a buccal infiltration of 1.8 mL 4% articaine with
1:100,000 epinephrine to a buccal plus lingual infiltration of the same solution (0.9 mL
47
buccal and 0.9 mL lingual) in achieving pulpal anesthesia in asymptomatic healthy
mandibular first molar teeth. The data was compared to the efficacy of an inferior
alveolar nerve block using 2% lidocaine with 1:80,000 epinephrine. Anesthetic success
was determined using an electric pulp tester. Buccal and buccal plus lingual infiltrations
of articaine with epinephrine did not differ in efficacy in obtaining pulpal anesthesia for
mandibular first molars. The results for the infiltrations were similar to that of an IAN
block using lidocaine with epinephrine. Patients were asked to report subjective tooth
numbness. Numbness was more common after an IAN block than a buccal infiltration.”
(23)
Nist et al. (93) compared the anesthetic effectiveness of 1.8 mL of 2% lidocaine
with 1:100,000 epinephrine using the conventional inferior alveolar nerve block, the
incisive nerve block, and a combination of the two techniques. Successful anesthesia of
the first and second premolars occurred with pulpal anesthesia lasting about thirty
minutes. The combination of the two techniques produced pulpal anesthesia in the first
and second premolars for one hour. In addition, the combination of the two techniques
enhanced pulpal anesthesia in the first molars.
Kanaa et al. (108) compared mandibular pulpal anesthesia following a 2%
lidocaine with 1:80,000 epinephrine inferior alveolar nerve (IAN) block with and without
buccal infiltration of 4% articaine with 1:100,000 epinephrine. Using a cross-over
design, thirty-six adult subjects received an IAN block followed randomly by either a
mock or true buccal infiltration of articaine. Pulpal anesthesia of the first molar,
premolar, and lateral incisor was assessed with an electric pulp tester until 45 minutes
post injection. Anesthesia was considered successful if two simultaneous maximum
48
readings of the pulp tester were measured. The IAN block with supplementary articaine
infiltration produced 91.7% anesthetic success in first molars, compared with 55.6% with
the IAN block alone. In the first molars, the authors found no difference in onset of
pulpal anesthesia between the two treatments. Duration of anesthesia at the first molar
was significantly longer when supplemental articaine was added. In conclusion, the
authors believed that the IAN block injection with a supplemental buccal infiltration of
articaine was more successful than the IAN block alone for mandibular teeth.
Aggarwal et al. (109) in a prospective, randomized double-blind study compared
the anesthetic efficacy of supplemental buccal and lingual infiltrations of either 1.8 mL of
2% lidocaine with 1:200,000 epinephrine or 1.8 mL of 2% articaine with 1:200,000
epinephrine in mandibular posterior teeth. Anesthetic success was determined by
subject’s reporting “none” or “mild” pain during endodontic access on a Heft Parker
visual analogue scale. Access was initiated 15 minutes after initial IAN block of 2%
lidocaine with 1:200,000 epinephrine. Supplemental anesthesia improved success from
an average 33% success to 47% with the lidocaine solution and 67% with the articaine
solution. Success rates between the solutions was significant (articaine significantly
better). In conclusion, the authors found that none of the techniques studied were
producing acceptable clinical success.
Pabst et al. (87) researched the anesthetic efficacy of a repeated infiltration
injection of articaine given 25 minutes following a primary articaine infiltration injection
in mandibular posterior teeth. “Using a cross-over design, 86 adult subjects (43 males and
43 females) with a mean age of 26.1 years randomly received two sets of injections
consisting of a primary infiltration injection of 1.8 mL of 4% articaine with 1:100,000
49
epinephrine plus a repeated infiltration injection 25 minutes later using either 1.8 mL of
4% articaine with 1:100,000 epinephrine or a mock buccal infiltration injection, in two
separate appointments spaced at least one week apart. The second molar through the first
premolar were tested with an electric pulp tester every 3 minutes for a total of 120
minutes. Additionally, subjects recorded the pain of injection and the postoperative
discomfort over the next three days.
Anesthetic success was determined using three definitions. Success #1 was
defined as achieving the first of two consecutive 80/80 readings by the third testing cycle
(7 minutes for molars and 8 minutes for premolars) and having the last of two
consecutive 80/80 readings at/or after 60 minutes of testing. Anesthetic success for
Group 1 (initial and repeated infiltration injections both with articaine) and Group 2
(initial articaine infiltration and mock repeated infiltration) were, respectively, as follows:
34.9% and 11.6% of the second molars; 48.4% and 9.3% of the first molars; 62.4% and
32.9% of the second premolars; and 59.0% and 24.1% of the first premolars. Analysis
with Multiple-Exact McNemar test showed a significant difference (p<0.0001) between
the solutions with each tooth type for success using this definition.”(27)
“Success #2 was described as achieving the first of two consecutive 80/80
readings with the electric pulp tester within 7 minutes of the injection for the molars, or
within 8 minutes of the injection for the premolars, and sustaining this reading
continuously for 60 minutes of testing. This definition excluded subjects who
experienced noncontinuous anesthesia, slow onset of anesthesia and anesthesia of short
duration. Anesthetic success by this definition for Group 1 and Group 2, respectively,
was as follows: 31.4% and 4.7% of second molars; 43.0% and 10.5% of first molars;
50
57.7% and 23.5% of second premolars; and 49.4% and 20.5% of first premolars. Again,
analysis with Multiple-Exact McNemar test showed a significant difference (p<0.0001)
between the solutions with each tooth type for success.
A final definition of anesthetic success (Success #3) was defined as the
occurrence of two consecutive 80 readings with the pulp tester within the first 60 minutes
of testing. Anesthetic success for Group 1 and Group 2 was, respectively, as follows:
84.9% and 69.8% of the second molars; 83.7% and 66.3% of the first molars; 97.7% and
78.8% of the second premolars; and 92.8% and 80.7% of the first premolars. Analysis
with Multiple-Exact McNemar test showed a significant difference (p<0.05) between the
groups with each tooth type for success. However, if this definition was applied to only
the first 25 minutes of testing, before the second articaine or mock infiltration injection
was given, success for Group 1 and Group 2 was, respectively, as follows: 66% and 67%
for second molars; 69% and 64% for first molars; 85% and 78% for second premolars;
and 86% ad 78% for first premolars. There were no statistically significant differences
(p>0.05) between the two groups in the first 25 minutes of testing.” (27)
Short duration of anesthesia, slow onset of anesthesia, and noncontinuous
anesthesia were also examined, yet only short duration demonstrated a significant
difference. When a repeat infiltration injection of articaine was given in Group 1, the
number of subjects exhibiting short duration of anesthesia (less than 60 minutes of
anesthesia) decreased significantly.
“Mean pain values for each of the three stages of the injection and for four
postoperative times were found to be in the mild range for each group tested. There was
no difference in pain ratings for any of the stages of injection between the two groups.
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Group 1 had statistically higher pain ratings immediately after anesthetic cessation and on
postoperative Day 1, but was not significantly different from Group 2 for postoperative
Days 2 or 3. Females experienced statistically higher pain than males during the solution
deposition of both groups and postoperatively in Group 1 after anesthetic cessation and
on Day 1, as measured on the VAS (p<0.05). As all mean pain values were in the mild
range, however, this was likely to be of little or no clinical significance.
In conclusion, a primary and repeated mandibular buccal infiltration injection
with articaine improved duration and success of pulpal anesthesia and decreased the
incidence of anesthesia of short duration when compared to a primary infiltration
injection alone in the mandibular first molar.” (27)
Anterior Infiltration:
Haas et al. (16) investigated the claim that anesthesia of mandibular pulpal and
lingual soft tissue, as well as maxillary palatal soft tissue, results following buccal
infiltration of articaine. Pulpal anesthesia was assessed by electric pulp tester readings
for a period of 25 minutes. Differences related to soft tissue anesthesia were also
analyzed. Lingual and palatal tissues were not expected to be anesthetized with a buccal
infiltration alone. The authors found that articaine was able to penetrate deep into the
tissue to result in lingual soft tissue anesthesia, at least in some subjects. Articaine was
more effective than prilocaine in the canine region in regard to pulpal anesthesia (50%
versus 37%) and mandibular lingual soft tissue anesthesia. Prilocaine, however, was
more effective than articaine in the palatal soft tissue anesthesia in the region of the
52
maxillary canines. These differences between articaine and prilocaine were not
statistically significant as determined by the chi-square analysis.
“Haas et al. (20) followed the same methods used in their previously described
double-blind randomized trial (16) to test local anesthetic infiltration for mandibular
canines. Again differences between 1.5 mL 4% articaine with 1:200,000 epinephrine and
1.5 mL 4% prilocaine with 1:200,000 epinephrine were compared. Twenty healthy adult
volunteers had the anesthetic solutions infiltrated next to the mandibular canine and
contralateral canine. Efficacy was again evaluated by electric pulp tester readings for 25
minutes. Differences related to soft tissue anesthesia were also analyzed. Lingual tissues
were not expected to be anesthetized with buccal infiltration alone. Articaine produced
successful pulpal anesthesia in 65% of the subjects compared to 50% for prilocaine.
Lingual tissues achieved anesthesia 10% of the time with articaine compared to 5% with
prilocaine. These differences, however, were again not statistically significant as
determined by the chi-square analysis.” (23)
Rood (110, 111)studied administration of bilateral inferior alveolar nerve blocks
and demonstrated that the pulps of central incisors were bilaterally innervated. In order
to decrease anesthetic failure occurring in 18 out of 20 patients, Rood added a labial
infiltration over the central incisor apex of 1 mL of lignocaine with 1:80,000 epinephrine
to the earlier administered IAN block of 1.5 mL of lignocaine with 1:80,000 epinephrine.
All central incisors became nonresponsive to the pulp tester. The success noted for 100%
of patients may be related to small sample size, but the study still showed a significant
improvement of pulpal anesthesia for the central incisor when the labial infiltration was
utilized.
53
Nist et al. (93) compared the anesthetic effectiveness of 1.8 mL of 2% lidocaine
with 1:100,000 epinephrine using the conventional inferior alveolar nerve block, the
incisive nerve block, and a combination of the two techniques. The incisive nerve block
alone did not successfully anesthetize the central and lateral incisors. Yet, the
combination of the two techniques enhanced pulpal anesthesia in the lateral incisors.
An evaluation of anesthetic efficacy between the inferior alveolar nerve block,
lingual infiltration, and a combination of the block with labial or lingual infiltration in the
mandibular teeth was done by Clark (112). Forty patients randomly received three
injection combinations at three separate appointments: an IAN block followed by a mock
lingual and mock labial infiltration, an IAN block followed by a mock lingual infiltration
and labial infiltration, an IAN block followed by a mock labial infiltration and lingual
infiltration. The standard IAN block was made using 3.6 mL of 2% lidocaine with
1:100,000 epinephrine, while the infiltration – injected over the apex of the lateral incisor
– utilized 1.8 mL of 2% lidocaine with 1:100,000 epinephrine. Anesthesia was
considered successful when two consecutive readings of 80 were obtained on the
electronic pulp tester within 15 minutes and were sustained for 60 minutes. All patients
experienced lip numbness with IAN blocks. The success rate for the lateral incisor was
40% with the IAN block alone, while the IAN block failed 30%. When labial infiltration
was added, the lateral incisor’s success 62% and the failure was only 12%. The success
rates for the IAN block plus lingual infiltration ranged from 38%-68%. The difference
between the IAN block alone and the IAN block plus labial infiltration was significant
(p<0.05) for both the lateral and central incisor. Yet, only the central incisor showed a
significant effect with lingual infiltration. Failure (no two-consecutive 80-readings
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within 60 minutes) rates were 10%-15% for labial infiltrations, and 15%-25% for lingual
infiltrations. The infiltrations alone were not effective in producing anesthesia in the
anterior teeth. However, either labial or lingual infiltration in combination with a
conventional inferior alveolar nerve block did increase the success rate of pulpal
anesthesia in mandibular lateral incisors from 40 to 62%.
Yonchak et al. (21) compared the anesthetic efficacy of infiltrations in mandibular
anterior teeth using either 1.8 mL of 2% lidocaine with 1:100,000 epinephrine or 1.8 mL
of 2% lidocaine with 1:50,000 epinephrine at two separate appointments in 40 subjects.
Additionally, 40 subjects were given a lingual infiltration of 1.8 mL of 2% lidocaine with
1:100,000 epinephrine. All injections were given over the apex of the lateral incisor and
teeth were blindly pulp tested at 4-minute intervals for 60 minutes post injection.
Anesthesia was considered successful when two consecutive 80 readings were obtained.
The success rates for the lateral incisor ranged from 43-50% for all three infiltrations.
The adjacent canine had success ranging from 27% (lingual) to 53% (labial with 1:50,000
epinephrine). The central incisor had success ranging from 47% (lingual) to 63% (labial
with 1:100,000 epinephrine). The authors concluded that there was no significant
difference in success between the labial infiltration of 2% lidocaine with 1:100,000
epinephrine and 1.8 mL of 2% lidocaine with 1:50,000 epinephrine or the lingual
infiltration of 1.8 mL of 2% lidocaine with 1:100,000 epinephrine when compared with
the labial infiltration of 1.8 mL of 2% lidocaine with 1:100,000 epinephrine. All
solutions demonstrated steady decline in pulpal anesthesia over 60 minutes. The authors
could not recommend use of any of the test solutions in providing profound anesthesia
over the lateral incisor apex.
55
Meechan and Ledvinka (13) found a combination of a labial and lingual
infiltration, using 2% lidocaine with 1:80,000 epinephrine, would significantly increase
success in mandibular anterior teeth over either a labial or lingual infiltration alone. The
study only incorporated 12 subjects in a repeated-measure design in which the central
incisor was tested for up to 30 minutes, at 2 minute intervals. Anesthetic success was
determined as no discomfort at the maximum reading of 80 μA on the electronic pulp
tester. The authors found the success of labial or lingual infiltration alone was 50%.
When a combined labial and lingual infiltration of 0.5 mL of 2% lidocaine with
1:100,000 epinephrine per side was administered, successful anesthesia was 92%. The
combination of labial and lingual infiltrations of lidocaine appears to have an increased
success compared to a single infiltration alone.
THE ELECTRIC PULP TESTER
“The Analytic Technology Vitality Scanner model 2001 (Analytic Technology
Corp., Redmond, WA) is a clinical device used in dentistry to determine the vitality or
nonvitality of teeth (36). It is currently marketed as the Kerr Electric Pulp Tester. The
unit is powered by five 1.5-volt (AA size) batteries. The output stimulus is generated by
a voltage source of 150 kilo-ohms internal impedance generating an output voltage that
ranges from 15 to 300 volts. The amperage output ranges from 0 to 50 microamps. The
unit has a digital readout indicating stimulus level on a scale of 0 to 80, with 0 signifying
no electrical output and 80 signifying maximum output. One count corresponds to one
burst of ten pulses of negative polarity followed by a space ten pulses long. The device is
one of constant current, meaning the current will remain stable, due to an increase in
56
voltage, if variable resistances are encountered. The intensity of the stimulus increases at
a rate preset on the control unit (113).
Once the probe contacts the tooth, the instrument turns on automatically. This
automatic turn-on feature prevents any testing unless a good electrical circuit is
established. After electrical contact has been made with the tooth, the intensity of the
stimulus increases slowly until a maximum output of 80 is reached or until the patient
indicates a sensation, at which time the probe is removed. The tester automatically resets
itself to zero output power once the probe is moved to another tooth. This feature
prevents the possibility of placing a probe that is delivering an electrical stimulus of
maximum intensity on an unanesthetized tooth. An indicator light on the probe signifies
when the unit is activated and the indicator lights on the display readout signify when the
batteries need to be recharged (113, 114).” (25)
“Kitamura et al. (115) reported the Analytic Technology Pulp Tester to be 100%
accurate when testing teeth previously determined to be nonvital, and 99% accurate when
testing teeth previously determined to be vital (1% false negative, no response). Cooley
et al. (114) reported two of thirty teeth having endodontic treatment gave false positives.
Dreven et al. (116) evaluated the electric pulp tester as a measure of analgesia in vital
teeth. They tested 34 “normal” teeth, 33 asymptomatic teeth with restorations, caries, or
crown fracture, and 30 teeth with the clinical diagnosis of irreversible pulpitis.
Anesthesia was then administered by block or by infiltration, and the teeth were then
pulp-tested for up to 10 minutes to determine if they responded to the maximum output.
Endodontic therapy was then performed on the teeth and pain, if any, was recorded.
Dreven et al. (116) found that 100% of the normal teeth, 100% of the asymptomatic
57
carious or restored teeth, and 73% of the teeth with irreversible pulpitis could be
instrumented painlessly after an “80” reading with the electric pulp tester was achieved
prior to the operative procedure.
Certosimo and Archer (8) evaluated the ability of the Analytic Technology
electric pulp tester to measure the level of local anesthesia prior to operative procedures.
Pre-operative baseline vitality measures were performed on the teeth to be tested. Only
vital teeth were included in this study. Anesthesia was then administered and 5 and 15
minutes were allowed for onset in the maxilla and mandible, respectively. Subjective
signs of anesthesia were confirmed and the teeth were again tested for analgesia using the
electric pulp tester. Operative procedures were started and patients were asked to rate
any sensation felt. If pain was felt during the procedure, supplemental injections were
given. Pain ratings were compared to the pulp test readings after the initial local
anesthetic was given. They found that the electric pulp tester was able to predict
difficulties in anesthesia with a 99% probability. The authors concluded that normal and
asymptomatic carious and restored teeth that obtained an “80” reading with the Analytic
Technology electric pulp tester are considered to have achieved profound pulpal
anesthesia. Teeth that respond at less than “80” have the potential for pain during
operative procedures. Both Dreven et al. (116) and Certosimo and Archer's (8) studies
showed that an “80” reading correlated with clinical anesthesia in normal, asymptomatic
teeth and that the electric pulp tester was an accurate means by which to evaluate local
anesthetic solutions and techniques in normal teeth.” (25)
“Mickel et al. (117) studied various interface media when using an electric pulp
tester. Of the liquids tested, Listerine® conducted the most voltage whereas, of
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nonliquids, K-Y® Brand UltraGel and Crest® Baking Soda & Peroxide Whitening Tartar
Control toothpaste conducted significantly higher voltages. These results suggest that
different interface media conduct differently, and that the interface medium should be
water-based and not petroleum-based. These results support a previous study by Martin
et al. (118) which found that the medium used in electric pulp testing is not significant
but should have a water base. Six electrode media were tested: Two types of toothpaste,
prophylactic paste, colloidal graphite, saline pad, and inert oil. The authors found no
significant difference between these media. It is unknown at this time why certain media
conduct better than others.” (119)
THE VISUAL ANALOGUE SCALE
“Since patients’ pain complaints are subjective reports of an otherwise
immeasurable stimulus, the sensitivity of the pain measures are constrained by the pain
rating scale employed (120). One common type of rating scale used is the verbal rating
scale (VRS), which is comprised of 5-7 word categories, such as ‘none’, ‘mild’,
‘moderate’, and ‘severe’ (121). Although it is the more traditional method for assessing
pain, it is insensitive in that it does not measure small changes (122). Furthermore, the
patient is forced to translate their feeling and perception into definitive words, and one
word may mean different things to different people (121).
The visual analogue scale (VAS) represents another method of assessing pain
perceptions. It is a line, the length of which is taken to represent the continuum of pain
gradations. It is a simple, sensitive, and reproducible instrument that enables a patient to
express the severity of his pain in such a way that it can be given a quantitative value.
59
The extremes of the line are taken to represent the limits of the pain experience; one end
is defined as ‘no pain’ and the other as ‘severe pain’. Huskisson (122) stated that the
VAS is ideal for crossover experiments, enabling one patient to express an opinion about
the relative value of different treatments.”(25)
“Since the VAS is difficult to use with no guides other than the endpoints, and
since the VRS only offers the patient 3 or 4 words to describe a full range of pain, a
compromise between the two instruments was developed in 1983 by Heft and Parker
(120).
The resulting graphic rating scale is a horizontal line with categorical descriptors
designated on the line. This scale offers more sensitivity than a category rating scale, and
is easier to use than a visual analogue scale. However, patients tend to cluster their
responses around the descriptors. For this reason, Heft and Parker (120) spaced the
words on the graphic rating scale reflecting the spacing between these descriptors as the
patient perceived them. Good correlation has been found between pain measurements
using visual analogue and simple descriptive pain scales (123).” (25)
TOPICAL ANESTHETIC
“Benzocaine (ethyl p-aminobenzoate) is an ester local anesthetic. It is used for
surface anesthesia in dentistry. It is not water-soluble; therefore it cannot be used for
injections. It is poorly soluble, poorly absorbed, and has a long duration of action.
Localized allergic reactions have been reported with repeated use. It is available for use
in a wide variety of preparations including flavored gels, liquids, and sprays (31, 33).
The research literature regarding the efficacy of topical anesthetics for reducing the pain
of the injection is equivocal. While some studies support its clinical efficacy, others do
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not (124). In 1979, a double-blind study by Gill and Orr (125) studied the effects of
Hurricaine, Zircaine, Xylocaine, and a placebo in palatal injections. For 54 subjects, the
topical was left in place for 30 seconds; a 25-gauge needle was placed into the palatal
mucosa, and then repeated on the contralateral side with a different topical solution. The
subjects rated the pain of needle placement on a scale of 1 to 5, on each side with a
different topical solution. Subjects reported no significant difference between any of the
agents tested. Meechan et al. (126) compared the effects of topical 5% lidocaine
ointment and topical eutectic mixture of local anesthetics (EMLA) cream on the
discomfort associated with intraligamentary injections. Volunteers had 5% lidocaine and
EMLA cream applied to the maxillary premolar buccal gingiva for 5 minutes before
administration of ligamental injections. Discomfort was assessed through use of a visual
analog scale. Their finding was that the injection discomfort on the side the EMLA
cream was applied was significantly less when compared to the lidocaine side. Their
conclusion was EMLA cream reduced the discomfort associated with intraligamentary
injections.”(24)
“Rosivack et al. (127) compared the effectiveness of benzocaine, lidocaine, and a
placebo when the topical was placed in the mucobuccal fold. The topical was left in
place for three minutes then a 27-gauge needle was inserted. The 60 participants were
asked to rank pain on a visual analog scale. The results indicated that both topical
anesthetics were significantly better than the placebo in reducing pain caused by needle
insertion, although no statistically significant differences were found between the two
topical anesthetics.
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Since the pain experience is more than a simple nociceptive sensation,
psychological factors may influence the efficacy of topical anesthetics. Many
psychological factors such as anxiety, fear, trust, perceived control over the painful
stimulus, interpretation of the painful situation, personality, and placebo treatments,
influence pain (128). Kincheloe et al. (129) studied the correlation of the expectancy of
pain, the use of topical anesthetic, and the perception of pain in the dental injection.
They included two experimental groups and 2 control groups in their study. The
experimental groups received topical anesthetic and the control groups received a placebo
but only one subgroup from each group were given instructions (that is, they were told
that they were given a topical anesthetic that would numb them and make the injection a
lot less painful). The other subgroup from each group was not given any instructions.
The results showed no significant pain reduction with the use of topical anesthetic versus
a placebo. However, when the subjects were analyzed according to their expectation of
pain, the subjects with high pain expectancy experienced a statistically higher (p<0.05)
amount of discomfort than those with low pain expectancy. Because the patients in this
study with high expectancy of pain fulfilled their expectations and experienced a more
painful injection than the low expectation patients, they concluded that good patient
management dictates that a dentist should attempt to assure the patient that everything
possible is being done to make them comfortable, such as the use of topical anesthetic.
Nusstein (130) compared the effectiveness of 20% benzocaine in reducing the
pain of needle insertion during maxillary posterior and anterior infiltration and inferior
alveolar nerve block injections. It was shown that the use of topical anesthetic reduced
the pain of needle insertion with the maxillary anterior injections, but there were no
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differences in pain ratings between the topical and no topical groups for the inferior
alveolar nerve block and posterior maxillary infiltration injections.” (24)
Nakanishi et al. (131) compared both the threshold of pain sensitivity and the
effect of topical anesthetic effect on reduction of pain upon needle insertion in the
posterior versus anterior mandible. Though only utilizing 27 subjects, the authors found
that the pain threshold in the anterior mucobuccal fold (adjacent to the canine and lateral
incisor) was significantly lower than the posterior premolar and molar region. Compared
with placebo, topical anesthesia also significantly reduced needle insertion pain for the
mandibular canine, but no significant difference was found in the posterior. The authors
concluded that topical anesthetic was efficacious in reducing needle insertion pain in
anterior sites, but not in posterior needle insertion. Due to the lower pain threshold and
the significant effect of topical in the anterior mandible, the authors suggest use of topical
in mandibular anterior teeth.
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CHAPTER 3
MATERIALS AND METHODS
Eighty-two adult subjects participated in this study. The subjects were in good
health and were not taking any medications that would alter their perception of pain.
Inclusion criteria were: between the ages of 18 and 65 years; in good health (ASA
classification I or II); informed consent granted. Exclusion criteria were: allergy to
articaine; history of significant medical problems (ASA classification III or greater);
depression, taken CNS depressants (including alcohol or any analgesic medications)
within the last 48 hours; pregnancy; lactating; or inability to give informed consent.
Specifically, subjects taking medications that could alter pain perception and/or alter
articaine metabolism were excluded. All female subjects were questioned regarding
pregnancy or suspected pregnancy and were not allowed to participate if pregnant,
suspected a pregnancy, were nursing, or were trying to become pregnant. If a female
wanted to participate and had revealed no possible pregnancy risk in both written and
verbal consent and medical history, she could refuse taking the urine pregnancy test.
Yet if a female wanted to participate and had any of the above pregnancy risks, she was
required to take a urine pregnancy test (Osom®, Genzyme Diagnostics Corp, San Diego,
64
CA) before participation, at the start of each appointment. Also excluded were subjects
who had contraindications to the injection technique or to the anesthetic solution (4%
articaine with 1:100,000 epinephrine). Approval for this study was obtained from The
Ohio State University Human Subjects Review Committee and written consent was
obtained from each participant. Patients were also asked to sign a Health Insurance
Portability and Accountability Act (HIPAA) release form.
The 82 blinded subjects randomly received two sets of injections consisting of a
combination labial infiltration injection of 1.8 mL of 4% articaine with 1:100,000
epinephrine (Septocaine, Septodont, New Castle, DE) plus mock lingual infiltration,
and a combination labial infiltration injection of 1.8 mL of 4% articaine with 1:100,000
epinephrine plus lingual infiltration of 1.8 mL of 4% articaine with 1:100,000
epinephrine in two separate appointments, spaced at least one week apart, in a crossover
design. With the crossover design, there were 164 total sets of combination infiltration
injections administered and each subject served as his/her own control. Forty-one sets
of infiltration injections were administered on the left side and 41 sets of infiltration
injections were administered on the right side. The same side randomly chosen for the
first set of infiltration injections was used again for the second set of infiltration
injections. All anesthetic solutions were checked to ensure that the anesthetic solution
had not expired. The test teeth chosen for the experiment were the mandibular lateral
incisor, central incisor, and canine. The contralateral maxillary canine was used as the
unanesthetized control to ensure that the pulp tester was operating properly and that the
subject was responding appropriately during each experimental portion of the study.
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Clinical examinations indicated that all teeth were free of caries, large restorations, and
periodontal disease; none had histories of trauma or sensitivity.
Before the experiment, the two sets of injections were randomly assigned sixdigit numbers from a random number table. Each subject was randomly assigned to
each of the two sets of injections to determine which injection set was administered at
each appointment. Only the random numbers were recorded on the data collection
sheets to blind the experiment.
The infiltration injections were administered using standard cartridges of articaine
and an aspirating syringe (Patterson Dental Supply, Inc., St. Paul, MN) equipped with a
27-gauge 1½” needle (Monoject, St. Louis, MO). Before the injection, each subject was
shown the visual analog scale (VAS) (Appendix H) and asked to rate the pain for each
phase of the injection - needle insertion, needle placement, and deposition of solution. A
Heft-Parker VAS (120) was used in this study. Per appointment, a total of six pain
rankings (representing the labial and lingual phases of injections) were made by each
patient after injections were completed. The patient was asked to mark a separate VAS to
rate the pain they experienced at each stage of each injection. The patient was verbally
informed of the specific stage of the injection immediately prior to commencement of
that stage. Following each infiltration or mock injection, the subject rated the pain for
each injection phase on the VAS. The categories were “insertion” (insertion of the
needle under the alveolar mucosa), “placement” (placement of the needle to the target
site), and “deposition” (deposition of the anesthetic solution at the target site.) Once the
injection was complete, the patient marked the pain experienced for each injection stage
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with an “X” on each corresponding VAS. This was done for both the primary labial
infiltration and mock or lingual articaine infiltration injection.
The VAS was a 170-mm line with various descriptive terms (see Appendix H).
The subjects placed a mark on the scale where it best described their pain level. To
interpret the data, the VAS was divided into the following four categories. No pain
corresponded to 0 mm on the scale. Mild pain was defined as greater than 0 mm and
less than or equal to 58 mm. Mild pain included the descriptors of faint, weak, and mild
pain. Moderate pain was defined as greater than 58 mm and less than 114 mm. Severe
pain was defined as equal to or greater than 114 mm. Severe pain included the
descriptors of strong, intense and maximum possible.
For the combination labial and lingual infiltration, the labial infiltration was
administered labial to the mandibular lateral incisor at the approximate location of the
apex. Following drying of the labial mucosa with sterile 2”x2” gauze and application of
a topical anesthetic agent (20% benzocaine gel, Patterson Dental Supply, Inc., St. Paul,
MN) for one minute, the lingual mucosa was dried and topical anesthetic was
administered following the same protocol as the labial infiltration, just prior to
commencement of the labial infiltration. The needle was then gently placed into the labial
alveolar mucosa (needle insertion) and was advanced within two to three seconds until
the needle was estimated to be at or just above the apex of the lateral incisor or target site
(needle placement). No effort was made to align the bevel of the needle in any particular
direction. After aspiration, the full cartridge of anesthetic solution was deposited over a
period of one minute (solution deposition). After complete deposition of the labial
infiltration, the lingual infiltration was administered lingual to the lateral incisor at the
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approximate location of the apex as described for the labial infiltration. For all injections,
labial infiltrations were completed before lingual infiltrations.
For the combination labial and mock lingual infiltration, the labial infiltration was
given as described above. The mock lingual injection consisted of needle penetration
only. The needle was bent over so it would not engage the cartridge – making it
impossible to inject anesthetic solution. The needle was held in the tissue for one minute
to mimic the actual infiltration injection. The subject rated the pain of the three phases of
the mock injection using the VAS even though the three phases were not done. To help
blind the injection, all subjects were blindfolded when they received the actual lingual
injection or mock injection. All infiltrations were given by the senior author (F N).
At the beginning of each appointment and before any injections were given, the
experimental teeth and control contralateral maxillary canine were tested three times
with the pulp tester (Kerr, Analytic Technology Corp., Redmond, WA) to record
baseline vitality. The tooth to be tested was isolated with cotton rolls and dried with
gauze. Crest Gel® toothpaste (Procter & Gamble Co., Cincinnati, OH) was applied to
the probe tip, which was then placed midway between the gingival margin and the
incisal edge of the tooth. The current rate was set at 25 seconds to increase from no
output (0) to the maximum output (80). Alkaline batteries (Energizer, St. Louis, MO)
were used and changed as needed. The number associated with the initial sensation was
recorded. Trained research personnel performed all pre-injection and post-injection
tests.
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One minute after completion of the sets of infiltration injections, the lateral
incisor and central incisor were pulp tested. At 2 minutes, the canine and the
contralateral, maxillary control canine were tested. At every 6 minutes, the
contralateral, maxillary canine, was tested by a pulp tester without batteries to test the
reliability of the subject. This cycle of testing was repeated every 2 minutes for 60
minutes. No response from the subject at the maximum output (80 reading) of the pulp
tester was used as the criterion for pulpal anesthesia. Anesthetic Success (Success #1)
was defined as achieving the first of two consecutive 80 readings with the electric pulp
tester within 10 minutes of the injection for the incisors, or within 11 minutes of the
injection for the canine, and sustaining this reading continuously for 60 minutes of
testing. To compare with many recent studies, successful anesthesia (Success #2) was
also defined as the occurrence of two consecutive 80 readings with the pulp tester
within the first 60 minutes of testing. However, this definition excluded subjects who
experienced complete failure. Failure was defined as no two consecutive 80 readings at
any time period within the 60 minute test period. Onset of pulpal anesthesia occurred at
the time of the first of two consecutive 80 readings. Noncontinuous anesthesia occurred
when the subject achieved two consecutive 80 readings, lost the readings, and then
regained at least two consecutive 80 readings prior to the end of the test period. Short
duration anesthesia occurred when the subject achieved the first of two consecutive 80
reading initially (i.e. within the first four test periods) and then lost the reading and
never regained it within the first 60 minutes of the testing period. Slow onset anesthesia
occurred when the first of two consecutive 80 readings did not occur until after the
fourth testing cycle (10 minutes for incisors and 11 minutes for the canine).
69
Subjects completed post-injection surveys after each set of infiltration injections
were administered (164 injection surveys given, 163 returned). The subjects rated their
pain in the injection area, both labially and lingually, using a VAS (Appendix H)
immediately after the numbness wore off and again each morning upon arising for three
days. Patients were also instructed to describe and record any problems, other than pain,
that they experienced (e.g., numbness, swelling, bruising, etc.). The forms were returned
to the clinic by the subjects after the three days had passed since the appointment.
Subjects were paid $35 for each of the two appointments and $5.00 for returning the VAS
forms, for a total of $75. The primary investigator was available to examine and evaluate
any post-injection problems.
The data from this study was collected and statistically analyzed. Between group
comparisons between the labial and lingual infiltration injections (Group 1) and the labial
and mock lingual infiltration injections (Group 2) for anesthetic success were analyzed
using the Multiple-Exact McNemar test. The incidence of anesthesia (80/80 readings)
was analyzed using Multiple-Exact McNemar tests and were adjusted using the Stepdown Bonferroni method of Holm. Between-group comparisons for onset time, relative
to the same tooth, were made using the Wilcoxon Matched Pairs test and the SignedRanks test. The independent variables in this analysis were age, gender, location (labial
or lingual) and group. Group 1 consisted of subjects who received articaine during both
the labial and lingual infiltration injections. Group 2 consisted of subjects who received
articaine during the labial infiltration injection only, and received a mock lingual
infiltration injection. Comparisons were considered significant at p<0.05.
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With a non-directional alpha risk of 0.05 and a power of 97% a sample size of
80 subjects was required to demonstrate a difference in injection pain of ± 15mm. With
a non-directional alpha risk of 0.05 and a power of 83% a sample size of 80 subjects
was required to demonstrate a difference in anesthetic success of ± 15%. With a nondirectional alpha risk of 0.05 and a power of 93% a sample size of 80 subjects was
required to demonstrate a difference in onset time of ± 3 minutes.
71
CHAPTER 4
RESULTS
Eighty-two adult subjects, 43 men and 39 women ranging in age from 19 to 56
years, with an average age of 26.7 years, participated in this study (Table 1).
Table 2 demonstrates the mean and relative standard deviation VAS values for
injection pain by Group 1 and 2 by location (labial or lingual), stage of injection, and
gender. No statistically significant differences were found between groups for insertion,
placement, or deposition (p>0.05), or within groups for gender (p>0.05). All mean pain
values for insertion and placement (regardless of location, group, or gender) fell within
the mild category. Lingual deposition for both groups also fell within the mild category.
Labial deposition for both groups resulted in mean moderate pain ratings.
Tables 3-5 describe the number and percentages of pain ratings that fell into the
none, mild, moderate, or severe categories for each stage of the injections. Primarily,
patients ranked their pain as mild 77%, 69%, and 60% of the time for needle insertion,
needle placement, and solution deposition, respectively. Although solution deposition
had higher pain ratings (Table 5), only approximately 2% of patients ranked their pain on
solution deposition as severe (6 out of 8 of the severe ratings were from labial injections).
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Tables 6-8 show between-group comparisons of percent 80/80 readings per tooth.
The Group 1 lateral and central incisors (Tables 6 and 7) had significantly more 80/80
readings by 4 minutes and continuously up to 58 minutes, when compared to Group 2.
The Group 1 canines (Table 8) had significantly more 80/80 readings at 8 minutes and by
17 minutes and continuously up to 59 minutes, when compared to Group 2. For the
lateral incisor (Table 6), greater than 75% of subjects in Group 1 had an 80/80 reading
from 7 minutes up to 40 minutes, while at no time point did 75% of subjects in Group 2
report an 80/80 reading. For the central incisor (Table 7), greater than 75% of subjects in
Group 1 had an 80/80 reading from 4 minutes up to 40 minutes, compared to 10 to 19
minutes for Group 2. For the canine (Table 8), greater than 75% of subjects in Group 1
had an 80/80 reading from 8 minutes up to 41 minutes, while at no time point did 75% of
subjects in Group 2 report an 80/80 reading.
Table 9 demonstrates anesthetic success for the lateral incisor, central incisor, and
canine with respect to two definitions. Anesthetic success (Success #1) was defined as
achieving the first of two consecutive 80 readings with the electric pulp tester within 10
minutes of the injection for the incisors, or within 11 minutes of the injection for the
canine, and sustaining this reading continuously for 60 minutes of testing. Using Success
#1, 49/82 (60%) patients in Group 1 had anesthetic success for the lateral incisor, while
only 6/82 (7%) in Group 2 had anesthetic success. Also, using Success #1, 46/82 (56%)
patients in Group 1 had anesthetic success for the central incisor, while only 5/82 (6%) in
Group 2 had anesthetic success. Finally, using Success #1, 35/82 (43%) patients in
Group 1 had anesthetic success for the canine, while only 8/82 (10%) in Group 2 had
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anesthetic success. With respect to definition #1, there was a significantly higher
anesthetic success for Group 1 (p<0.0001) for all teeth types.
Anesthetic success (Success #2) was also defined as the occurrence of two
consecutive 80 readings with the pulp tester within the first 60 minutes of testing, which
does not exclude short duration, slow onset, and non-continuous anesthesias (as in
Success #1) . For this definition, 80/82 (98%) patients in Group 1 had anesthetic success
for the lateral incisor, while only 62/82 (76%) in Group 2 had anesthetic success. Also
using Success #2, 81/82 (99%) patients in Group 1 had anesthetic success for the central
incisor, while only 67/82 (82%) patients in Group 2 had anesthetic success. Finally using
Success #2, 76/82 (93%) patients in Group 1 had anesthetic success for the canine, while
only 61/82 (74%) patients in Group 2 had anesthetic success. With respect to Success #2,
there was a significantly higher anesthetic success for Group 1 for all tooth types
(p<0.05).
Table 10 demonstrates anesthetic failure for the lateral incisor, central incisor, and
canine. In Group 1, only 2/82 (2%) patients had anesthetic failure for the lateral incisor,
while 20/82 (24%) in Group 2 had anesthetic failure. Only one (1%) patient in Group 1
had anesthetic failure for the central incisor, while 15/82 (18%) in Group 2 had anesthetic
failure. In Group 1, only 6/82 (7%) patients had anesthetic failure for the canine, while
21/82 (26%) in Group 2 had anesthetic failure. Anesthetic failure was significantly higher
for Group 2 (p<0.05), when compared to Group 1 for all tooth groups (Table 10).
The time of onset of pulpal anesthesia is shown in Table 11. There was a
statistically significant difference noted between the groups (Group 1<Group 2) for the
central incisor and the canine (p<0.05), but due to the large standard deviations that
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include the means, this statistical difference is not meaningful. Actual clinical onset time
would also include an additional 2 to 2.5 minutes from the start of the initial injection
because of time allotted for a labial and lingual injection (1 minute each), plus removal
and reloading of the syringe. This results in a clinical onset time ranging from 5.5 to 7.5
minutes for lower anterior teeth when utilizing labial and lingual infiltration injections.
Table 12 shows the incidence of short duration anesthesia, non-continuous
anesthesia, and slow-onset anesthesia for Groups 1 and 2. Short duration anesthesia was
statistically higher (p<0.0001) in Group 2 for all teeth, as seen in Table 12. The number
of patients with short duration in Group 1 was 19, 26, and 21 versus 47, 57, and 42 for
Group 2, with respect to the lateral incisor, central incisor, or canine. Significantly more
patients in Group 2 had short duration anesthesia for all teeth. Non-continuous anesthesia
represented a very small sample (i.e. 5 out of 183 for Group 1, and 11 out of 183 for
Group 2). Also, slow-onset represented a very small number of patients (i.e. 4 out of 183
for Group 1, and 13 out of 183 for Group 2). For both non-continuous anesthesia and
slow-onset anesthesia, no statistical differences between groups 1 and 2 were noted for
the lateral incisor, central incisor, or canine (Table 12).
Postoperative pain ratings are presented in Table 13. For all postoperative days
surveyed, no statistical differences were found within groups between males and females
(p>0.05). For both the day of testing (Day 0) and the day after testing (Day 1), both male
and female patients reported statistically higher mean postoperative pain ratings for the
labial and lingual infiltrations (Group 1) compared to the labial and mock infiltration
(Group 2).
For postoperative days 2 and 3, no statistically significant differences were
seen between groups (p>0.05). For all postoperative days surveyed, pain ratings
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continually decreased from day 0 (with the highest mean value of 51.3 + 35.1 mm) to day
3 (with the lowest mean value of 7.5 + 14.5 mm).
Postoperative pain ratings by group and day are summarized in Tables 14-17. On
the day of testing (Day 0) between Group 1 and Group 2, 12% versus 29% reported no
pain, 58% versus 62% reported mild pain, 27% versus 8% reported moderate pain, and
2% versus 1% reported severe pain (Table 14). On the day after testing (Day 1) between
groups 1 and 2, 29% versus 51% reported no pain, 58% versus 42% reported mild pain,
12% versus 7% reported moderate pain, and 1% versus 0% reported severe pain (Table
15). On postoperative day 2 between groups 1 and 2, 39% versus 64% reported no pain,
58% versus 31% reported mild pain, 3% versus 6% reported moderate pain, and neither
group reported severe pain (Table 16). On postoperative day 3 between groups 1 and 2,
60% versus 69% reported no pain, 39% versus 29% reported mild pain, 1% versus 2%
reported moderate pain, and neither group reported severe pain (Table 17). Overall,
labial plus lingual injections (Group 1) produced statistically higher mean postoperative
pain ratings than the labial plus mock injection (Group 2). Yet in all postoperative days
for either group or gender, mean pain ratings fell in the mild category (Table 13).
Tables 18-1 and 18-2 describe the frequency of postoperative complications by
day for both Group 1 and 2 and by location (labial or lingual). Generally, complications
diminished from day 0 through day 3. Both groups reported a higher frequency of
postoperative soreness to touch, swelling, and bruising at the labial injection site when
compared to the lingual site. Pain on opening, soreness to chewing, and nausea were
associated with both locations and groups, with a relatively low frequency of occurrence
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(0-4%). Out of a possible 326 responses, there were only three (< 2%) reports of pain on
chewing, 1 (< 1%) report of headache, and 2 (1 %) reports of nausea.
Table 19 shows the overall numbers and percentages of postoperative
complications. Soreness to touch was the most frequently reported complication: 50
reports out of 162 (31%) had soreness to touch in Group 1, compared with 38 out of 164
(23%) in Group 2. In most categories of postoperative complications, the labial injection
produced more complications than the lingual. Although relatively few patients reported
complications, pain on opening and soreness to chewing were more commonly noted at
the lingual injection site when compared to the labial (2.5% and 1.2% versus 1.2% and
0.6% respectively).
The incidence of pulpal anesthesia (80 readings across time) for the labial
followed by the lingual infiltration (Group 1) and the labial followed by the mock
infiltration (Group 2) by tooth (lateral incisor, central incisor, and canine) is presented in
Figures 1-3. For Group 1, greater than 75% of patients reported an 80 reading from 7
minutes up to 40 minutes for the lateral incisor (Figure 1), from 4 minutes up to 40
minutes for the central incisor (Figure 2), and from 8 minutes to 41 minutes for the
canine (Figure 3). Yet in Group 2, the central incisor was the only tooth to have a
percentage of 80 readings greater than 75% for any time period (from 10 to 16 minutes).
The labial plus lingual injection (Group 1) statistically improved pulpal anesthesia in all
tooth groups.
77
CHAPTER 5
DISCUSSION OF MATERIALS AND METHODS
Selected portions of the following have been adapted from previous theses by
Pabst (27) from the Division of Endodontics at The Ohio State University College of
Dentistry.
Eighty-two adult subjects participated in this study of which 43 were males and
39 were females. Reviews by Unruh (132)and Miaslowski (133) have indicated that
there are differences between males and females regarding clinical pain experiences.
Unruh (132) reported that females have higher levels of pain, have pain more frequently,
and have a longer duration of pain than do males. The similar sample size of both males
and females tested in the current study was an attempt to reduce gender as a confounding
variable.
“The population of subjects came mostly from The Ohio State University. Most
subjects were educated and tended to be dental students, dental hygiene students, college
students, and dental assistants. For this reason, it could be that this group may not have
been representative of that portion of the population who is fearful of dental procedures
or those who have difficulty in obtaining profound anesthesia. All subjects were in good
health as determined by a written health history and oral questioning. Good health was a
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prerequisite to be in this study to help avoid possible contraindications to the use of local
anesthetic with epinephrine, and to ensure the absence of systemic problems that could
negatively affect anesthetic efficacy. People who are in poor health may take
medications such as tricyclic antidepressants, nonselective β-adrenergic blockers, or
adrenergic neuron blockers, including guanethidine, which relatively contraindicates the
use of local anesthetic solutions containing epinephrine (134). In addition, systemic
health problems can reduce the effectiveness and duration of local anesthetics.”(27) The
age range for the subjects in this study was from 19 to 56 years, with a mean of 26.7
years. “Nordenram and Danielsson (135) found that local infiltration injections were
more effective in elderly patients than a younger age group. The authors speculated that
this effect might be due to a higher pain threshold in the elderly. Since we studied a
relatively young adult population, the results of this study may not apply to children or
the elderly. The subjects had no contraindications to the injection techniques, nor the
solutions tested.” (27)
An over-the-counter pregnancy test, Osom® hCG-Urine Test, was utilized to rule
out pregnancy before females participated in the study. The Osom® pregnancy test
detects human Chorionic Gonadotropin (hCG), which is present in urine only during
pregnancy. The Genzyme Diagnostics Corporation claims that urine specimens
containing as low as 25 mIU/mL hCG will yield positive results when tested with the
Osom® hCG-Urine Test (136). In normal pregnancy, hCG levels in urine can reach 25
mIU/mL as early as 7 to 10 days post conception, and continue rising to reach a
maximum concentration in excess of 200,000 mIU/mL at the end of the first trimester
(137). McCready et al. (138) claimed that 25 mIU/mL can be detected as early as two to
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three days before expected menses. In one clinical study, 40 urine specimens were tested
with the Osom® hCG-Urine Test and the results were compared to results obtained from
other commercially available visual tests for hCG. The Osom® hCG-Urine Test, when
compared to other tests, resulted in a sensitivity of 100% and a specificity of 100% (136).
All female subjects were questioned regarding pregnancy or suspected pregnancy
and were not allowed to participate if pregnant, suspected a pregnancy, were nursing, or
were trying to become pregnant. If a female wanted to participate and had revealed no
possible pregnancy risk in both written and verbal consent and medical history, she could
refuse taking the urine pregnancy test. Yet if a female wanted to participate and had any
of the above pregnancy risks, she was required to take the Osom® urine pregnancy test
prior to both appointments. The reason for excluding pregnant or potentially pregnant
women was due to the potential unknown risks of articaine to the fetus. To determine the
risks associated with the use of drugs in pregnancy, the FDA classifies prescription drugs
based on fetal injury risk. The Categories range from A to X. Drugs in Categories A and
B are considered safe for use, as no adverse effects have been demonstrated in humans.
Drugs in Category C, like articaine, may be used based on animal studies, but no
controlled human studies are available. Category D and X drugs have been associated
with adverse effects in humans and should be avoided.
“Articaine is classified in Category C by the Food and Drug Administration.
There have been no adequate or well-controlled studies in human pregnant women.
Leuschner et al. (73), however, studied the toxicologic profile of 4% articaine with
1:100,000 epinephrine in vitro and in vivo for repeated dose toxicity, reproduction
toxicity, mutagenic potential, and local tolerance in animals. In their study, rats and dogs
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were subjected to repeated subcutaneous administration of 4% articaine. Reproduction
studies were evaluated at doses ten times the maximum recommended human dose of 7
mg/kg/day and showed no evidence of harm to the fetus or to other related aspects of
reproduction. This was true even when the doses were toxic to the parental animals. The
mutagenicity studies also showed no mutagenic potential up to cytotoxic concentrations
or up to the maximum tolerated dose levels. The authors concluded that the local
tolerance of articaine was very good. The data indicated that articaine did not possess
any relevant side effects or toxicity and could be considered a safe local anesthetic.
However, animal reproduction studies are not always predictive of human responses (63)
and, therefore, articaine should be used during pregnancy only if the potential benefit
justifies the potential risk to the fetus.”(27)
“The basic reason for eliminating pregnant patients in this study was for medicolegal reasons. If a patient were knowingly pregnant and participated in this study and had
a miscarriage or a baby with a fetal defect, they could attempt to correlate participation in
this study with those problems. Naturally occurring congenital anomalies occur in 3% of
the general population, yet causes can be determined in less than 50% of these cases
(139). Therefore, it seemed prudent, in our litigious society, to eliminate this population
group.”(23)
“The subjects’ motivation to participate in this study may have been for financial
gain, a desire to learn more about anesthesia and the different injection techniques, or an
interest in endodontics. All subjects were financially compensated for their participation
at a rate of $35.00 per visit. Upon completion of all post-injection questionnaires, the
subject was paid an additional $5.00 as an incentive to return the forms. A total of
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$75.00 was paid to each subject who completed the study and returned both postinjection questionnaires. Participation in this study was voluntary in accordance with
The Ohio State University Human Subjects Committee.
This study involved a human test model that simulated a clinical setting. Animal
studies can demonstrate the relative potency of various local anesthetics; however, animal
studies cannot be used to directly correlate anesthetic effect in humans.” (27) For this
reason, the use of a human test model allowed direct correlation between anesthetic
volumes.
“The pulpal anesthesia produced by the anesthetic solution was evaluated by the
use of the electric pulp tester. Bjorn (124) recommended the use of the electric pulp
tester to evaluate the effects of local anesthetic solutions. McDaniel et al. (140) reported
that the electric pulp tester was safe to pulpal tissue. They showed that the use of the
electric pulp tester did not produce histological changes, such as necrosis or
inflammation. Brynolf (141) demonstrated that repeated applications of a local anesthetic
followed by electric pulp testing did not alter the initial threshold response values in a
given subject. These findings enabled the subjects, who participated in this study, to be
given injections and to be pulp-tested in two successive appointments. The repeated
measures technique used in this study controlled the variable of sex, age, anatomic
variations and individual responses (141) to the electric pulp tester (114, 142).”(27)
This study utilized the Kerr (Vitality Scanner 2006) electric pulp tester to test the
anesthetic effectiveness of 1.8 mL of 4% articaine with 1:100,000 epinephrine given as a
single or repeated buccal infiltration injection. “Myers (143) reported telephone
conversations with SybronEndo which revealed that the Analytic Technology (Vitality
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Scanner 2005) and the Kerr (Vitality Scanner 2006) electric pulp testers were identical in
form and function, with the only difference being the labeling on their display faces.
Since they are constructed and function identically, data collected with the Analytic
Technology and Kerr electric pulp testers can be compared without the type of pulp tester
being a factor. The Analytic Technology electric pulp tester has been shown by Cooley
et al. (114) and Kitamura et al. (115) to be extremely accurate (97-99%). This instrument
has an internal resistance of 150 k/ohms in order to negate the effects of high resistance
in teeth as recommended by Bjorn (124) and Mumford and Bjorn (144). The maximum
voltage of this instrument is 300 volts. One hundred and forty volts was found, by
Matthews (145, 146) to be sufficient to stimulate all vital pulps in normal, asymptomatic
teeth. Fifty microamperes is the maximum amperage of the Kerr electric pulp tester. The
current output must be sufficient to stimulate the pulpal tissue but not to stimulate tissues
beyond the confines of the tooth. A current of 50 microamperes was found to be
sufficient by Pepper and Smithe (147) and Matthews (146), to stimulate healthy pulps
and a current of 200 microamperes was necessary to stimulate the surrounding
periodontal tissues. Researchers have recommended the use of an electric pulp tester,
which stimulates with cathode polarity, since tissues have a lower threshold for
stimulation using cathode polarity, rather than anode polarity (144, 145, 147). Matthews
(145, 146) also suggested that a constant current stimulation system be used. This results
in a more valid vitality reading in comparison to an impulse current stimulation system.
A constant current system allows the current output to remain stable even if variable
resistances are encountered in tooth structures (113).” (27)
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“The Kerr electric pulp tester was utilized in this study because it functions by the
aforementioned criteria. The unit delivers a cathodal polarity current output from 0 to 50
microamperes and generates an output voltage that ranges from 15 to 300 volts. It
possesses an internal resistance of 150 k/ohms and is a constant current stimulation
system (113). During the study, the rate of voltage increase was calibrated so that the
elapsed time to obtain an 80 reading starting from a 0 reading was approximately 25
seconds. This rate of voltage increase was chosen because Kleier et al. (148) found that a
slow rise in voltage output (25 seconds to go from 0/80 to 80/80) resulted in a
significantly less painful response to the patient when compared to a more rapid rise (5
seconds to go from 0/80 to 80/80). Alkaline batteries were used and changed as needed
to ensure adequate power supply.”(27)
“Dreven et al. (116) used the Analytic Technology pulp tester to measure clinical
analgesia in normal teeth, asymptomatic carious or restored teeth with a clinical diagnosis
of irreversible pulpitis. In their study, the teeth were tested with the electric pulp tester
ten minutes after anesthetic solution administration. If a reading of 80/80 was obtained, a
pulpectomy was performed on the tooth to test clinical analgesia. If a reading of 80/80
was not obtained after ten minutes, then supplemental injections were administered until
a reading of 80/80 could be obtained. Once a reading of 80/80 was obtained, a
pulpectomy was performed to test clinical analgesia. Profound pulpal anesthesia was
obtained 100% of the time in normal and in asymptomatic carious or restored teeth.
Profound pulpal anesthesia was obtained in only 73% of the teeth with a diagnosis of
irreversible pulpitis. They concluded that normal, asymptomatic carious and restored
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teeth that obtained an 80/80 reading with the Analytic Technology electric pulp tester
were considered to have achieved profound pulpal anesthesia.” (27)
“Furthermore, Certosimo and Archer (8) concluded from their study that the
Analytic Technology electric pulp tester was an accurate predictor of the level of clinical
pulpal analgesia in asymptomatic carious teeth. Their results showed that a reading of
80/80 with the Analytic Technology electric pulp tester predictably indicated that the
patient would experience no pain during cavity preparation procedure. In addition, they
found that soft tissue signs of anesthesia were not reliable indicators of local anesthesia.
All subjects had soft tissue signs of anesthesia; however, 21% of the subjects experienced
pain during tooth preparation. All of these subjects had readings less than 80. It is on
these findings that we base the interpretation of our data in this study.” (27)
“Prior to pulp testing, all teeth were dried with a 2x2 inch cotton gauze and
isolated with cotton rolls. Stephan (149) and Narhi et al. (150) showed that if the
experimental teeth were not dried adequately, there could be a response to electrical
stimulation of the periodontal tissues resulting in a false positive response. Cooley et al.
(114) and Cooley and Robinson (151) showed that wet teeth may allow shunting of the
electrical stimulus resulting in false negative responses. The electrode medium chosen
for this experiment was Crest® gel toothpaste. Martin et al. (118) compared various
brands of toothpaste, as well as other water-based media, as an electrolyte for electric
pulp testing. They found no differences among the media tested in terms of conductance
ability from the pulp tester to the tooth. Crest® gel was preferred over non-gel
toothpastes because it did not dry out as quickly, it had a thicker viscosity which
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minimized flow, and its water solubility allowed easy removal from the tooth with a wet
gauze.” (27)
“The principal investigator and trained assistants performed the electric pulp
testing. Both the assistants and the subjects were blinded to the solutions being used at
each appointment. The experimental teeth and control tooth were tested two times with
the Kerr electric pulp tester prior to the injection. The readings were recorded and served
as baseline information. The baseline information was used to determine if all the test
teeth were vital. If any teeth registered 80/80 two straight times, they were determined to
be non-vital which disqualified that side of the subject’s mandible from the study. If this
occurred, the testing was done on the patient’s contralateral side and the next applicable
master list L/R designation was reversed so that left and right sides were equally
represented overall.” (27)
“All testers wore non-latex or vinyl gloves to conform to infection control
guidelines. The Kerr electric pulp tester was supplied with an electrical lead that attached
to both the electrode and a lip clip. The lip clip could be held by hand or placed on the
lip to establish the necessary contact to complete the electrical circuit required by the
electrical pulp tester. The probe was placed flat against the buccal or facial enamel in the
middle third of the clinical crown. Jacobson (152) evaluated probe placement sites on
anterior and premolar teeth using an oscilloscope, an Analytic Technology pulp tester and
extracted teeth. He found placing the probe on the incisal edge or the occlusal two-thirds
of facial enamel of the tooth was the best location for the placement of the probe. This
placement used the minimal voltage necessary to stimulate the pulpal fibers. It also
reduced the likelihood of stimulation of the nerve fibers in the gingiva. Bender et al.
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(153) showed that the condition of the tooth enamel affected the threshold response.
They felt that optimal probe placement location in non-anesthetized anterior teeth was on
the incisal edge. Recently, Lin et al. (154) aimed to determine the best location for probe
placement on first molars. They found the lowest threshold for EPT response to be on
the mesiobuccal cusp tip. A progressive increase in readings from the mesiobuccal cusp
tip to the middle third of buccal surface was found; however, these differences were not
significant. There were no significant differences between maxillary and mandibular
molars or between male and female subjects. In this study we used the middle third of
the clinical crown to remain consistent with previous studies conducted by the Division
of Endodontics at The Ohio State University.” (27)
“This study used a repeated-measures design in which each subject was seen at
two appointments scheduled at least one week apart. Brynolf (141) observed that the
initial threshold values of the experimental teeth were unaffected by the repeated
administration of local anesthetics and electrical pulp testing. McDaniel et al. (140)
found that an electric pulp tester at maximum current strength did not histologically
affect the pulp or cause inflammation or necrosis.”(27) The one-week minimum period
between appointments was selected to allow time for healing of possible post-injection
sequelae, similar to the studies of Mason (155), Mikesell (26), Robertson (25), Haase
(19), and Pabst (27).
A master list (Appendix G) was generated prior to the beginning of testing, with
164 random six-digit numbers. Two of these numbers were assigned to each patient
number (1 through 82) to identify at each appointment whether the second injection
would be performed as an articaine or a mock injection. The order of the two methods
87
was randomly generated to prevent the subjects and assistants from knowing the identity
of the injection being given. Therefore, half of the subjects received a labial infiltration
at the apex of the lateral incisor with 1.8 mL 4% articaine with 1:100,000 epinephrine
and a mock lingual injection at the first appointment and a labial and lingual infiltration
injection of 1.8 mL of 4% articaine with 1:100,000 epinephrine at the second
appointment, and the other half received the injections in the reverse order. Randomizing
the sequence helped prevent subject bias in terms of injection pain and anesthetic
efficacy. All anesthetic cartridges were checked to ensure their expiration date was after
the projected end of the study. A letter code, R or L, was assigned to denote whether the
labial infiltration injection was to be given on the subject’s right or left side. This
ensured that an equal number of right- and left-sided injections were given. Both
solutions were given on the same side in each subject. This was done to remove the side
of injection as a variable, and to establish reproducibility for each injection so the
subjects could accurately compare the effects of each solution on the same teeth and same
tissues. The principal investigator performed all mandibular labial and lingual infiltration
injections.
An equal number of mandibular left and right sides were tested to attempt to
eliminate right versus left side as a variable: 41 subjects received left-sided injections and
41 received right-sided injections. It is unknown if anesthetic success varies on the right
or left side, or what influence a right or left handed operator has on the anesthetic success
of the side injected.
The assistants and subjects were unaware of the solution being given since they
were not shown the syringe prior to and during injection. This avoided any bias or
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preconceived ideas concerning discomfort or their ability to get numb with any particular
anesthetic volume.
“Berlin (156) reported that although the 4% articaine with 1:100,000 epinephrine
solution is supplied in a cartridge labeled 1.7 mL, the volume delivered was equal to 1.8
mL of anesthetic in other dental cartridges (i.e. 1.8 mL of 2% lidocaine with
epinephrine). Weaver (62) acknowledged that articaine anesthetic cartridges actually
contain 1.8 mL of solution. The FDA requires the manufacturer to indicate the solution
as a 1.7 mL cartridge because some anesthetic cartridges were found to occasionally
contain slightly less than 1.8 mL of solution (62).” (27) Robertson et al. (14) also noted
that although the articaine cartridge was externally marked as containing 1.7 mL, on
average the solution expressed was equal to 1.76 mL, which is the same average volume
expressed from 1.8 mL externally-marked lidocaine cartridges. Overall, a small volume
of anesthetic solution remains in the cartridge after delivery of the solution.
The labial and lingual infiltration injection was administered using a standard
aspirating syringe and a 27-gauge 1½-inch needle. This gauge needle was chosen since it
is the most commonly used in dentistry (157). The 27-gauge needles used in this study
were consistent with those of previous studies conducted by the Division of Endodontics
allowing comparisons to be made and additional data to be collected to corroborate the
results of past studies.
“Twenty percent benzocaine gel was utilized as topical anesthetic in this study.
The use of topical anesthetic has been advocated as an aid in reducing the pain of needle
insertion. While Rosivack et al. (127) demonstrated the effectiveness of topical
anesthetic, Gill and Orr (125) and Kincheloe et al. (129) showed no significant pain
89
reduction with the use of topical anesthetic. Nusstein et al. (130) conducted a study to
compare the effectiveness of 20% benzocaine in reducing the pain of needle insertion
during maxillary posterior and anterior infiltration and inferior alveolar nerve block
injections. Logistic regression analysis showed no differences in pain ratings between
topical and no topical groups for the inferior alveolar nerve block and posterior maxillary
infiltration injections. The use of topical anesthetic did reduce the pain of needle insertion
with the maxillary anterior injections. For the inferior alveolar nerve block injection,
Yonchak et al. (12) and Nist et al. (6) concluded that there was not a significant
difference in patient discomfort following application of topical anesthetic, Vaseline, or
nothing to the site of injection. Martin et al. (128) found that if the patient thought they
were receiving topical, whether they did or not, pain ratings were lower. Therefore, the
most important aspect of using topical anesthetic may not be its clinical effectiveness, but
rather the psychological effect on the patient who feels the practitioner is doing
everything possible to prevent pain (128).” (27) In contrast, Nakanishi et al. (131) found
a lower pain threshold and the significant effect of topical in the anterior mandible,
suggesting an anatomic difference in mandibular anterior teeth and recommending topical
usage. The principal investigator chose to use topical anesthetic due to both the
psychological effect and the evidence from Nusstein et al. (130) and Nakanishi et al.
(131) showing efficacy for use with infiltration injections.
The lateral incisor was chosen as the principal test tooth over which the anesthetic
was deposited due to its central location relative to the mandibular anterior quadrants,
between the canine and central incisor whether right or left, as well as in an effort to
better compare to other lower anterior studies in which the lateral incisor was also chosen
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as the principal test tooth (3, 21). For the combination labial and lingual infiltration, the
labial infiltration was administered labial to the mandibular lateral incisor at the
approximate location of the apex. Following drying of the labial mucosa with sterile 2x2
gauze and application of a topical anesthetic agent (20% benzocaine gel, Patterson Dental
Supply, Inc., St. Paul, MN) for one minute, the lingual mucosa was dried and topical
anesthetic was administered following the same protocol as the labial infiltration, just
prior to commencement of the labial infiltration. After complete deposition of the labial
infiltration, the lingual infiltration was administered lingual to the lateral incisor at the
approximate location of the apex as described for the labial infiltration. For all injections,
labial infiltrations were completed before lingual infiltrations.
All injections were given by the principal investigator. This was done to ensure
uniformity with the injection technique. With the subject’s mouth open, the operator’s
free hand retracted the lower lip and the labial mucosa adjacent to the anterior teeth. The
direction of the needle insertion was from a superior and anterior direction into the labial
vestibule. In an effort to keep consistent with previous studies, the infiltration injection
was administered using a standard aspirating syringe (Patterson Dental Supply, Inc., St.
Paul, MN), and the aforementioned 27-gauge, 1½-inch needle (Monoject, St. Louis,
MO).
“After initial penetration, the needle was advanced to the target site within two to
three seconds. The needle was advanced until the tip of the needle was estimated to be at
or just above the root apex. No effort was made to align the bevel of the needle in any
particular direction. Malamed (158) states that ‘The orientation of the needle bevel is not
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a significant factor in the success or failure of an injection technique.’ As the needle was
advanced over a period of 2 to 3 seconds, no anesthetic solution was deposited.
After reaching the target site, aspiration was performed, and the full cartridge of
the anesthetic solution (articaine) was deposited over a period of one minute. A oneminute period for solution deposition is recommended in Walton’s text (159) as a means
of reducing patient discomfort during injection. ‘Slow deposition of solution permits its
gradual distribution into the tissues…As a general rule, solution deposition should take
approximately 1 minute per cartridge.’(159) The needle was removed after completing
solution deposition.” (27)
“In a clinical situation, many dental procedures require 60 minutes or less to be
completed. The key to providing dental treatment in a timely manner is having fast
anesthesia onset for both soft and pulpal tissues. Delayed anesthesia onset results in
prolonged treatment times, which can cause the dentist to fall behind with the remainder
of the day’s patient schedule. In addition, the duration of anesthesia seems to be most
important during the first hour while treatment is performed and completed. Thus, the
clinical protocol of utilizing a labial and lingual infiltration of articaine in lower anterior
teeth may help to reduce onset time and delayed anesthesia, while increasing anesthetic
duration, compared to a single labial infiltration.
Robertson et al. (14) found that a single buccal infiltration injection of 1.8 mL 4%
articaine with 1:100,000 epinephrine was effective for pulpal anesthesia but did not last
for a time period that would be adequate for a typical dental appointment lasting one
hour. Scott (152) found that reinjection of anesthetic at 30 minutes after an initial
maxillary infiltration injection was effective in greatly prolonging the duration of pulpal
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anesthesia in the maxillary central and lateral incisor, and canine. She did not analyze
true duration as the test teeth were still numb at 90 minutes, the end of the test period.
However, she showed that for the central incisor, at 90 minutes, 13% of teeth without the
supplemental injection were numb, while 58% of the central incisors that received the
supplemental injection were numb. She also showed that for the lateral incisor, at 90
minutes, 33% of teeth without the supplemental injection were numb, while 90% of the
lateral incisors that received the supplemental injection were numb.” (27)
Meechan and Ledvinka (13) found a combination of a labial and lingual
infiltration, using 2% lidocaine with 1:80,000 epinephrine, would significantly increase
success in mandibular anterior teeth over either a labial or lingual infiltration alone. The
study only incorporated 12 subjects in a repeated-measure design in which the central
incisor was tested for up to 30 minutes, at 2 minute intervals. Anesthetic success was
determined as no discomfort at the maximum reading of 80 μA on the electronic pulp
tester. The authors found the success of labial or lingual infiltration alone was 50%.
When a combined labial and lingual infiltration of 0.5 mL of 2% lidocaine with
1:100,000 epinephrine per side was administered, successful anesthesia was 92%. The
combination of labial and lingual infiltrations of lidocaine appears to have an increased
success compared to a single infiltration alone, yet duration could not be analyzed due to
the short test period (i.e. 30 minutes). In the present study, our aim was to determine the
anesthetic success and duration of a buccal and lingual combination infiltration injection
utilizing 1.8 mL of 4% articaine with 1:100,000 epinephrine, when compared to a single
buccal infiltration injection utilizing 1.8 mL of 4% articaine with 1:100,000 epinephrine.
From the results found in the study by Meechan et al. (13), the current study assumed that
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an increase of both the anesthetic efficacy and duration would occur with the addition of
the lingual infiltration, leading to a more successful approach to mandibular anterior
anesthesia.
Subjects were asked to rate any pain felt during the three stages of the injection
for both the front (i.e. labial) and the back (i.e. lingual) injections using a hybrid Visual
Analog Scale (VAS). This scale consisted of a 170 mm horizontal line with various
demarcations which have descriptive pain terms. These included; none (0 mm), faint (22
mm), weak (37 mm), mild (58 mm), moderate (83 mm), strong (112 mm), intense (142
mm), and maximum possible pain (170 mm), placed along the VAS from left to right.
The three stages surveyed included: needle insertion, needle placement, and solution
deposition. Each stage had its own VAS for recording the pain experienced. During the
injection, the principal investigator stated “insertion”, “placement”, and “deposition” at
the time that each stage of the injection commenced. The subjects were told to make a
mental note of the pain intensity caused at each of the three stages. Once the injection
was completed, the subjects would place a mark on each of the six VAS lines (two VAS
lines per stage of injection) to describe their level of pain, but not necessarily at the
markings with the descriptive terms.
“The visual analog scale is a line, the length of which is taken to represent the
continuum of some type of experience like pain. It is a simple, sensitive, and
reproducible instrument that enables a patient to express the severity of his/her pain in
such a way that it can be given a numerical value (122). The scale is ideal for crossover
experiments, enabling one patient to express an opinion about the relative value of
different treatments. The extremes of the line are taken to represent the limits of the pain
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experience; one end is therefore defined as “no pain” and the other as “severe pain”
(122).
The scale may be vertical or horizontal (122). Although 4- and 5-point scales
have wide acceptance in literature, they appear to lack sufficient sensitivity to measure
the pain experience (120). Since a visual analog scale is difficult to use with no guides,
other than the endpoints, a hybrid between the two scales was developed in 1983 by Heft
and Parker (120). The resulting graphic rating scale is a horizontal line with category
word designations on the line (120). Clusters of results tend to occur around descriptors
when a vertical VAS is used (122). However, when the line is horizontal this grouping is
not seen (122). Good correlation has been found between pain measurements using
visual analog and simple descriptive pain scales (123).
Kreimer (160) investigated the efficacy and pain of injection of 2% lidocaine with
1:100,000 epinephrine versus a solution of 2% lidocaine with 1:100,000 epinephrine and
1.82 mL mannitol. He used both a hybrid visual analog scale and a numerical scale. The
numerical scale consisted of 4 pain ratings: 0 = none; 1 = mild; 2 = moderate; 3 = severe.
The hybrid visual analog scale had 8 descriptive words on a 170 mm scale. The mean
correlation value for all of the pain ratings was reported as 0.92. These results showed a
very high correlation between the visual analog scale and the numerical scale. Kreimer
(160) stated that the results obtained from the visual analog scale were easier to analyze
statistically. Therefore, Kreimer (160) felt that the visual analog scale was superior to the
numerical pain scale.” (27)
The experimental teeth selected for this study were the mandibular lateral incior,
central incisor, and canine. Clinically normal pulps were evaluated in this study. Only
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virgin or minimally restored teeth were used. Teeth exhibiting active caries, periodontal
disease, extensive restorations or a previous history of sensitivity disqualified that
particular quadrant of teeth from participation in the study. “Bjorn (161) demonstrated
that repeatable and reliable threshold values were attainable with the electric pulp tester
on clinically normal teeth. Dreven et al. (116) showed that an 80/80 reading obtained
with the electric pulp tester correlated with complete clinical analgesia in intact, carious
or minimally restored teeth, with clinically normal pulps. Furthermore, Certosimo and
Archer (8) found that the Analytic Technology electric pulp tester was an accurate
predictor of the level of clinical pulpal analgesia in asymptomatic carious teeth.” (27)
Post-injection evaluation timing began immediately after the needle was
withdrawn. Digital timers were used to keep pace with the post-injection time intervals.
The pulp testing began one minute after the second injection (whether mock or true
lingual) was completed. After initial needle penetration into the labial mucosa for either
group (1 or 2) until pulp testing commenced, the time elapsed was equal to at least 3
minutes and up to 3.5 minutes. The elapsed time would account for a 1 minute labial
injection, a 1 minute mock/lingual injection, and a 1 minute time period between
completion of the mock/lingual injection and the first cycle of testing that began with the
lateral incisor. The additional 0.5 minute represents an approximate time period for
removal, reloading, and replacement of the syringe into the lingual vestibule. The rate of
voltage increase on the electric pulp tester was set at 25 seconds for the electric pulp
tester to reach an 80 reading. This rate of increase automatically excluded more than two
teeth being pulp tested each minute. At 1 minute post-injections, the experimental lateral
and central incisors were tested with the electric pulp tester and the results were recorded.
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At 2 minutes post-injections, the canine was tested. The contralateral maxillary canine
served as both a positive and a negative control. At 2.5 minutes post-injections, the
positive control canine was tested. As a positive control, testing the non-anesthetized
canine assured that the electric pulp tester was operating correctly. On every third cycle
for the contralateral maxillary canine, the ground wire was removed from the electrical
wand to evaluate the reliability of patient responses. This third cycle acted as the
negative control. A positive response with the negative control would have disqualified
the subject from further participation in this study. This did not occur. This testing cycle
was implemented in order to remain consistent with the testing technique used in the
similar mandibular anesthetic studies of Fernandez (162), Ridenour (163), Palo (164),
Wolf (165), Smith (166), Cohen (167), Mikesell (168), Robertson (14), Haase (15), and
Pabst (87). This testing cycle was repeated every 3 minutes for the 60-minute duration of
the study.
Two definitions of success were used in our study. Success #1 was defined as
achieving the first of two consecutive 80/80 readings by the 4th testing cycle and
continuously sustaining this reading throughout the first 60 minutes of testing. This
definition would ensure that, clinically, the subject would be numb for the entire 60minute dental appointment and would not feel pain at any point during treatment. Other
studies have also defined pulpal anesthesia using definitions similar to this (3, 14, 87) and
can therefore be compared to our results.
Success #2 was defined simply as the occurrence of two consecutive 80 readings
at any time during the first 60 minutes of testing. Using this definition means that the
patient may only have a minimum of 6 consecutive minutes of pulpal anesthesia during
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the testing period and this may occur at any time. Therefore this definition is not as
clinically useful as the first definition. Only for the purpose of direct comparison to
previously published studies (6, 14, 16, 18, 20-22, 87, 107) and not for clinical relevance,
this second definition has been utilized in the current study.
Anesthetic failure was considered to have occurred if the subject never achieved
two consecutive 80 readings. Readings of less that this would indicate that anesthetic
duration only lasted for approximately 3 minutes, which would be clinically
unacceptable. Teeth that respond to an electric pulp tester at values less than 80 are
likely to elicit a painful response when pulpal procedures are performed (8, 140).
Onset was evaluated for each of the three teeth tested. For our study, an onset
time of 10 minutes for the test tooth (11 minutes for the canine) was considered clinically
acceptable and comparable to currently published research (87). This should allow
enough time for pulpal anesthesia to take place while not delaying the initiation of
treatment. Onset was also evaluated with respect to the completion of the second
injection (i.e. lingual, mock or real). Group 1 received a volume of 3.6 mL of 4%
articaine with 1:100,000 epinephrine, while group 2 only received 1.8 mL of the same
anesthetic solution. Because both groups did not receive identical volumes at the
commencement of the study, it was expected that onset would be faster for Group 1.
Mean onset of pulpal anesthesia was determined, and a between group comparison was
done for each tooth – lateral incisor, central incisor, and canine (Table 11). True clinical
onset time would have to consider the time from the start of the injections (estimated to
be at least 2-2.5 minutes) to the mean time when anesthesia occurred for the patients.
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Data for duration of anesthesia was not analyzed because the testing period in this
study was not open-ended. For practical scheduling purposes, the pulp testing did not
continue indefinitely, until each tooth lost anesthesia. However, general duration trends
comparing the group receiving a repeated buccal infiltration with articaine versus a mock
infiltration are shown in Figures 1 through 3.
Utilizing the definitions of anesthetic success and failure above, other anesthetic
results (outcomes) become apparent. The absence of “success” does not necessarily
equate to “failure,” and vice versa. Noncontinuous anesthesia occurs when the subject
achieves two consecutive 80/80 readings, loses the readings, and then regains the 80/80
readings prior to the end of the test period. In a retrospective review of thirteen studies
done at The Ohio State University, Nusstein et al. (169) found that noncontinuous
anesthesia following an IAN block occurred from 12-20% of the time when 1.8 mL 2%
lidocaine with 1:100,000 epinephrine was used and from 8-20% of the time with 3.6 mL
of the same solution was used. Mikesell et al. (170) found an incidence of 3-22%
following a maxillary infiltration of 1.8 mL 2% lidocaine with 1:100,000 epinephrine and
0-3% with the 3.6 mL volume. Pabst found the incidence of noncontinuous anesthesia
for mandibular posterior teeth using 3.6 mL of 4% articaine with 1:100,000 epinephrine
(in a repeated infiltration injection) to fall between 15.7-24.4% (27). In the same study,
Pabst (27) found noncontinous anesthesia to range between 9.6-16.3%, when using a
single infiltration of 1.8 mL of 4% articaine with 1:100,000 epinephrine. In a clinical
setting, patients going in and out of anesthesia would result in patient discomfort during
treatment, leading to a possible delay in completing treatment, and the potential
unnecessary injection of more anesthetic solution. Because these subjects were included
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in our second definition of success, the first, more strict definition was analyzed in order
to exclude subjects exhibiting noncontinous anesthesia.
Short duration anesthesia occurred when the subject achieved the first of two
consecutive 80 readings initially and then lost the reading and never regained it within the
first 60 minutes of the testing period. “Nusstein et al. (169) found this to occur less than
12% following an IAN block with either 1.8 mL or 3.6 mL 2% lidocaine with 1:100,000
epinephrine. Mikesell et al. (170) observed an incidence of 42-72% and 9-44% following
a maxillary infiltration with 1.8 mL and 3.6 mL of 2% lidocaine with 1:100,000
epinephrine, respectively. Clinically, it would be desirable for anesthesia to last for at
least 60 minutes so that dental procedures could be completed with a minimal chance of
patient discomfort.” (27)
Slow onset anesthesia occurs when the first of two consecutive 80 readings does
not occur until after the fourth testing cycle (10 minutes for incisors and 11 minutes for
the canine). Following an IAN block, slow onset occurred 19-27% of the time with 1.8
mL of 2% lidocaine with 1:100,000 epinephrine and 19-22% of the time with the 3.6 mL
volume (169). Clinically, slow onset could result in treatment delay and/or pain and
discomfort if the dental procedure was started before the patient achieved profound
pulpal anesthesia. In addition, the dentist could hastily assume anesthetic failure and be
inclined to give unnecessary, additional anesthesia in an attempt to increase success.
Teeth with slow onset and short duration of anesthesia would not meet the criteria
for success under Success #1 because either the onset would be longer than the fourth
testing cycle or the duration would not last throughout the 60-minute testing period, both
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of which are required by this definition. These outcomes also would not meet our
definition of failure (no consecutive 80/80 readings obtained at any time). However,
Success #2 (two consecutive 80/80 readings at any time) would include patients with
slow onset and short duration of anesthesia.
All subjects were provided a take-home survey to complete after each
appointment. This survey asked the subjects to rate any postoperative pain felt from the
injection sites for 3 days using a VAS (Appendix H). The subjects completed the initial
part of the survey once they felt the anesthetic had completely worn off, indicated by
normal sensation in the subjects’ teeth and soft tissues. The subjects continued to rate
any postoperative pain felt from the injection sites upon waking each morning for the
next three days. It was felt that respondents would be more likely to take the time to
record any symptomotology they were experiencing before they became involved with
their daily activities. The frequency of reporting was chosen to be once daily as opposed
to multiple reports to further increase patient compliance. A VAS, the same as that
utilized to report injection pain, was used for this survey (Appendix H). Subjects also
recorded any postoperative complications (swelling, tissue damage, etc.), relative to the
location of the injection (i.e. labial or lingual). The postoperative categories included in
this study were chosen in order to make direct comparisons to previous studies (19, 27)
and not to suggest that these complications would or should be expected clinically from
infiltration injections. The purpose of this was to reveal and document any possible
sequelae in hopes of understanding the mechanism of their etiology.
The data from this study were collected and statistically analyzed. Betweengroup differences in needle insertion pain, needle placement pain, solution deposition
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pain, and postoperative pain were analyzed using both the ANOVA and Tukey-Kramer
tests due to the repeated-measures study design. Incidence of anesthetic success and
failure were analyzed using a Multiple-Exact McNemar test. Between-group
comparisons for the probability of pulpal anesthesia (80/80 EPT reading) by tooth, time
period and group were analyzed using Multiple-Exact McNemar test and were adjusted
using the step-down Bonferroni method of Holm. Failure was analyzed by using a
Multiple-Exact McNemar test. Anesthesia onset times were analyzed using the Wilcoxon
Matched Pairs test and the Signed-Ranks test. Comparisons were considered significant
at p<0.05.
With a non-directional alpha risk of 0.05 and a power of 97% a sample size of 80
subjects was required to demonstrate a difference in injection pain of ± 15mm. With a
non-directional alpha risk of 0.05 and a power of 83% a sample size of 80 subjects was
required to demonstrate a difference in anesthetic success of ± 15%. With a nondirectional alpha risk of 0.05 and a power of 93% a sample size of 80 subjects was
required to demonstrate a difference in onset time of ± 3 minutes.
DISCUSSION OF RESULTS
Selected portions of the following have been adapted from previous theses by
Pabst (27), Robertson (25), Evans (119), Haase (19), Steinkruger (171), and Jensen (172)
from the Division of Endodontics at The Ohio State University College of Dentistry.
“All the teeth used in this study were clinically normal, with no history of
sensitivity, no active caries, no large restorations, and no periodontal disease. This
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ensured that the pulps evaluated in this study were clinically normal. Inflammatory
conditions of the pulp affect clinical anesthesia (173); therefore, only asymptomatic,
clinically normal teeth were used in this study. The experimental model used in this
study was a repeated-measures design and therefore the distribution of age, weight, and
gender between the two subject groups was identical.” (27)
Discussion of Age
The average age of the participants in the study was 26.7 years (Table 1).
“Nordenram and Danielsson (135) investigated different anesthetic parameters, such as
onset time, frequency of anesthesia, duration of tooth anesthesia, and soft tissue
numbness of commonly used dental local anesthetics in healthy older subjects. The
authors found that the anesthetic solutions tested were more effective in the older group
than the younger group. Nordenram and Danielsson (135) speculated that this might be
due to a higher pain threshold in the older group due, possibly, to reduced vascularity,
fatty degeneration of bone tissue, or secondary dentin formation. Therefore, due to our
low mean age, the results of the current study may not be applicable to older subjects.
Additionally, children under the age of 18 were not included in this study and the results
of the study may not be applicable to children.” (27)
Discussion of Weight Related to Dosage of Articaine
“The maximum recommended dose of anesthetic solution that should be given as
a dental injection is dependent on the subject’s weight. The maximum recommended
dose for 4% articaine with 1:100,000 epinephrine is 7 mg/kg (66), with epinephrine being
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the limiting factor. In 1954, the New York Heart Association recommended that the
maximum epinephrine dose be limited to 0.2 mg per appointment (174). This dose is
usually reduced if the patient is a child or the patient has a medical condition that limits
the use of a vasoconstrictor. Bennett (175) recommended that the maximum dose of
epinephrine in a cardiac risk patient should be no more than 0.04 mg. This equates to
approximately two 1.8 mL cartridges with a 1:100,000 epinephrine concentration.”(27)
In this study, the maximum amount of anesthetic solution injected during a single
appointment was 144 mg (3.6 mL) of articaine. Additionally, the maximum amount of
epinephrine injected during a single appointment was 0.036 mg. These values were all
well below the maximum allowable dosages for the normal, healthy, adult subjects used
in this study.
Discussion of Gender related to Pain and Anesthesia
Thirty-nine females and 43 males were included in this study (Table 1). “Even
with a repeated-measures design, it is important to have an approximately equal number
of males and females because it is possible that a particular anesthetic may work
differently depending on the subject’s gender. If this were the case, the results would not
necessarily be applicable to the gender with low representation in the study.”(27) In our
study, both genders were similarly represented.
For statistical analysis, pain of injection and post-treatment pain were measured.
The effect of differences in reporting pain between genders was controlled by having a
similar distribution of subjects. “Many studies have found differences between sexes
regarding pain tolerance. Liddel and Locker (176) surveyed 5,061 adults about their
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thoughts and feelings regarding dental treatment. A five-point rating scale ranging from
1 (relaxed) to 5 (extreme fear) was used to measure dental anxiety and the experience of
dental pain. Another four-point scale ranging from 1 (strongly agree) to 4 (strongly
disagree) was used to measure pain avoidance, acceptance of pain, and fear of pain. The
results showed that women were significantly more anxious about dental treatment than
men (p<0.001) and dental anxiety decreased significantly with age (p<0.001). In
addition, women said they would try to avoid pain more, accept pain less, and fear pain
more than men (p<0.001).”(27) This research suggests that females may experience
higher pain than males.
“Fillingim et al. (177) studied clinical pain experiences, thermal pain thresholds,
and pain tolerance in 209 (117 female and 92 male) healthy young adults. The subjects
underwent thermal pain assessment, including the determination of their warmth
detection threshold, their thermal pain threshold, and their thermal pain tolerance. The
authors found that women had a significantly lower warmth detection threshold, thermal
pain threshold, and thermal pain tolerance than men (p<0.001). Results showed a strong
correlation between the thermal warmth detection and the thermal pain threshold. These
results imply that the sex difference might be due to a generally enhanced
somatosensation rather than a difference in nociceptive processing in women. Therefore
the authors re-analyzed the difference in thermal pain threshold and thermal pain
tolerance after statistically controlling for warmth detection. Women still showed
significantly lower thermal pain threshold and thermal pain tolerance levels compared to
males (p<0.001). Fillingim et al. (177) suggested that pain responses may be more
clinically relevant for females than males. The authors concluded that the contributing
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factors may include hormonal alterations (177, 178), resting blood pressure (179), and
psychological factors (180). Other investigators have reported that other contributing
factors, such as sex role expectancies (181) and anxiety (182) may also moderate
differences in pain tolerance seen between sexes.”(27) This research suggests that
females have both psychological and physiological reasons for experiencing higher pain
than males.
“Keogh et al. (183) studied the effects of two different attentional strategies
(focused versus avoidance) on how males and females responded to experimentally
induced pain. Subjects attempted to place their non-dominant hand in an ice bath for up
to 2 minutes. Pain threshold (the point of just noticeable pain), pain tolerance (the point
at which the patient could not tolerate further pain and withdrew their hand from the
water), and pain recovery (the time needed for pain to dissipate after the subject withdrew
her/his hand) were measured. The subjects were then divided into 2 groups, the
avoidance group and the focused group. The avoidance group was asked to focus their
thoughts on things other than the cold water and the focused group was asked to
concentrate on the sensations that their hand was having when placed into the cold water.
Keogh et al. (183) found that males had a significantly higher tolerance for cold pressor
pain than females. The authors also found that males, who were given attentional focus
instructions, had lower sensory pain compared to males whom were instructed to avoid
pain. This was not true with the female groups.”(27) When comparing genders, this
research suggests that males may have a physiologically higher pain threshold and a
psychological ability to distract themselves from the pain experience.
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In order for the results of this study to be considered valid for both sexes, it was
important that both males and females participated in this study. Differences due to
gender were possible in our study with regard to pain reported during needle insertion
and placement, solution deposition, and postoperatively. Yet within groups, males and
females showed no statistically significant difference in mean pain ratings with regard to
stage of injection or postoperative pain (Table 2 and 13). Although not statistically
different, for all stages of injection, locations, and postoperative days within groups,
males reported lower mean pain ratings than females (Tables 2 and 13). For both groups
and gender, the means for the stages of injections and postoperative pain fell within the
“mild” category, with the exception of labial placement (females only) and labial
deposition, which had “moderate” pain ratings. Generally, males and females together
experienced an average of “mild” pain, while males consistently reported a lesser pain
experience than females (although it was not statistically different). In other words, for
each stage of injection and postoperative day, males reported lower mean pain ratings
than females (Tables 2 and 13). Although the previously mentioned studies showed that
males report and experience statistically less pain than females, our study only
statistically shows that males and females report similar pain. This difference may be
due to operator and/or patient population differences. Though having a larger sample
size in general allows research to detect smaller differences that could have existed, our
study design encorporated enough subjects to detect gender differences and found them
to be statistically insignificant. Overall, the study found males and females to experience
similar pain relative to the anterior mandibular infiltrations.
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The only statistical difference in pain noted for stages of injections was that both
males and females rated labial deposition as significantly more painful (p<0.05) than a
lingual injection (Group 1). For males in Group 1, the mean labial pain rating for
deposition was 58.3 mm, while the mean lingual pain rating was 42.5 mm. For females
in Group 1, the mean labial pain rating for deposition was 65.1 mm, while the mean
lingual pain rating was 48.6 mm. For the labial injection, both male and female mean
pain ratings were in the “moderate” category. For the lingual injection, both male and
female mean pain ratings were in the “mild” category. Pabst (27) only found a
significant gender difference in pain ratings for solution deposition in the primary
injection for both groups; however no significant differences were found for needle
insertion or placement for either group. Similarly, a significant difference in postoperative pain ratings between genders was seen in the repeated injection during Day 0
and Day 1 (Table 19). All other post-op time periods for Groups 1 and 2 showed no
significant difference in male versus female post-operative pain ratings. Although, Pabst
(27) found gender differences for some stages of injection and some postoperative days,
this wasn’t consistent for all stages and postoperative days. Our study showed a trend
towards males reporting less pain, but this was not significant. This difference may be
due to operator and/or patient population differences. The fact that gender was not
statistically different shows it to be less of a confounding variable in the design of our
study. Gender analysis, as detected in the study, showed that females and males
experienced pain similarly.
“Two baseline electric pulp test readings for the experimental and control teeth
were recorded prior to the injections at each appointment. Bjorn (161), using the electric
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pulp tester on teeth, showed that daily variations in the thresholds of clinically normal
teeth were not significantly different. Hinkley et al. (4), McLean et al. (2), and Vreeland
et al. (1) statistically compared baseline pulp test readings at three different appointments
spaced approximately one week apart. They showed no significant differences in
baseline electric pulp test readings. In the current study, baseline electric pulp test
readings were recorded. The values were not statistically analyzed because they were
used only to assure that the experimental teeth were vital.”(27)
PAIN OF INJECTION
During the injection procedure, subjects rated pain for needle insertion, needle
placement, and anesthetic solution deposition for both the labial and lingual injections
(whether true lingual or mock). For every subject, the labial injection was the primary
injection while the lingual or mock lingual injection was secondary or supplemental. The
total time elapsed for both injections was approximately 2 minute to 2.5 minutes. This
represents the time required for insertion and placement of the needle at both sites, the 1
minute for solution deposition at both sites, and the reloading of the syringe between the
two injections.
Pain on Needle Insertion
Data for the mean insertion pain ratings for Group 1 and Group 2 are reported in
Table 2. The number and percentage of pain ratings per category (“none”, “mild”,
“moderate”, or “severe”) are presented in Table 3 for needle insertion. The data for
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needle insertion pain ratings is reported in Appendix H. Data was statistically analyzed
for both groups by location (labial and lingual) and within groups by gender for needle
insertion. For Group 1, labial needle insertion resulted in a mean pain rating of 39.1 mm
(“mild” pain), compared to 39.8 mm (“mild” pain) for Group 2. Both mean values were
in the “mild” pain category. For Group 1, lingual needle insertion resulted in a mean pain
rating of 33.8 mm (“mild” pain), compared to 38.2 mm (“mild” pain) for Group 2. Both
mean values were in the “mild” pain category. For Group 1, eighty-three percent of the
labial pain ratings were in the none-to-mild category while 17% were in the moderate-tosevere category (Table 3). For Group 2, eighty-one percent of labial pain ratings were in
the none-to-mild category while 19% were in the moderate-to-severe category (Table 3).
For Group 1, eighty-five percent of the lingual pain ratings were in the none-to-mild
category while 15% were in the moderate-to-severe category (Table 3). For Group 2,
eighty-three percent of lingual pain ratings were in the none-to-mild category while 17%
were in the moderate-to-severe category (Table 3). Statistical analysis of needle insertion
pain ratings found no significant differences between the two groups for location and
gender (Table 2). These statistically similar findings were anticipated since both groups
received identical labial and lingual insertions. When evaluating the gender differences
in pain ratings during needle insertion, no differences (p>0.05) were found between
males and females within either Group 1 or Group 2 (Table 2). For insertion pain, no
statistical difference was found between a labial injection and lingual injection (p>0.05).
Because all injections were given by the principal investigator, operator difference was
not a factor in the findings of this study.
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The pain rating results from our study can be compared with previous posterior
mandibular studies. Robertson (25), who gave a posterior mandibular buccal infiltration
injection with either 4% articaine with 1:100,000 epinephrine or 2% lidocaine with
1:100,000 epinephrine, found mean needle insertion pain with articaine to be 23.9 mm
and with lidocaine to be 27.0 mm. Also in a posterior mandibular buccal infiltration
study, Pabst (27) found the means to be 19.6 mm in the repeated buccal articaine
infiltration group and 21.7 mm in the single buccal articaine infiltration group. These
ratings were both in the “mild” pain range. In the current study, our mean values for
insertion ranged from 33.8 mm to 39.8 mm, falling within the “mild” category. Our
means were higher than those of the above studies, but this may be due to the anterior
location. Nakanishi et al. (131) found that, compared with placebo, the mandibular labial
mucosa had a significantly lower pain threshold compared with the posterior mandible.
Subjects experienced greater pain with the anterior location of needle insertion, compared
with the posterior location. Due to the lower pain thresholds discovered, one would
expect a higher mean pain rating for anterior needle insertion compared to posterior.
Some of the difference could also be explained by differences in the sampled population
between studies.
Also the higher mean insertion pain values may be due to differences in the
number of sites of penetration, adding to subject’s perception of more pain. Having two
injections physiologically traumatizes two sites and may lead to an increased
psychological fear compared to a single injection. Our study differed from Pabst (27)
and Robertson (25), in that the subjects had two separate sites for tissue trauma (labial
and lingual). The labial and lingual combination would potentially double the area of
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trauma compared with Robertson’s single buccal infiltration (25). The difference
between traumatizing the same location twice, as in Pabst study (27) and traumatizing
two separate locations may be significantly different. Further research would need to be
done to verify this.
Overall, the “mild” mean pain ratings could still be attributed to the use of topical
anesthetic. Topical anesthetic was utilized in our study at the site of needle penetration
prior to administration of the labial or lingual infiltration injections. Robertson’s study
(25), and Pabst’s study (27) also used topical in the same manner. “Mikesell et al. (170)
evaluated the effect of using topical anesthetic on maxillary infiltration injection pain
ratings. Ninety-six volunteers participated in the study. Before each injection,
approximately 0.2 mL of topical anesthetic or placebo was passively placed for 60
seconds. For all injections, three minutes were used to administer the local anesthetic.
The results showed that for the maxillary lateral incisor with topical anesthetic, 81%
reported none-mild pain and 19% reported moderate-severe pain. For the maxillary
lateral incisor without topical anesthetic, 66% reported none-mild pain, and 34% reported
moderate-severe pain. There were no statistically significant differences between the
topical anesthetic group and the placebo group for the maxillary lateral incisor (p=0.129).
Nusstein and Beck (130) evaluated 20% benzocaine as a topical anesthetic for three
injection types. They found that it had no effect on injection pain for inferior alveolar
nerve block injections or for maxillary posterior infiltrations. The use of topical
anesthetic did reduce the amount of pain reported by patients for maxillary anterior
infiltrations.”(27)
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In a study by Kanaa et al. (18), topical anesthetic was not used for the mandibular
buccal infiltration. Pain ratings were recorded for the overall injection pain, whereas our
study rated each phase of the injections. “Because of this difference in pain evaluation,
direct comparison of injection pain between the two studies cannot be made. In addition,
Kanaa et al. used a 100 mm VAS without descriptors between the endpoints, while the
Heft-Parker VAS utilized in our study is 170 mm with descriptors between the endpoints.
Still, it can be determined that in both studies, the mean VAS scores for needle
penetration were in the ‘mild’ category as defined for each scale.”(27) In another study,
Corbett et al. (88) compared the efficacy of a buccal infiltration with articaine to buccal
plus lingual infiltration with articaine and found the mean pain of overall injection to be
20.9 mm on a 100-mm VAS without topical anesthesia. Although it cannot be directly
compared to our pain measurement scale for the same reasons as stated above, the values
found in this study correlate to the “mild” pain levels found in our study. Buccal alone
and buccal plus lingual infiltration injections were also compared for efficacy of pulpal
anesthesia of the mandibular first molar using lidocaine in a study by Meechan and
Kanaa (22). The overall pain of injection was recorded on a 100-mm VAS. The mean
pain of injection for a buccal infiltration was 17.8 mm for 1.8 mL of solution and 19.6
mm for 0.9 mL of lidocaine solution. Both means correlated with a “mild” pain rating.
Nist et al. (6) also used a 100-mm VAS when evaluating an incisive nerve block with
lidocaine and no topical anesthetic. The mean score for needle insertion of 9.23 mm was
in the ‘mild’ pain category as defined for this scale.”(27) With a small number of
subjects, Meechan and Ledvinka (13) utilized the 100-mm VAS to evaluate pain in labial
and lingual infiltrations with 2% lidocaine 1:80,000 epinephrine in mandibular central
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incisors. The authors did not report the use of topical anesthetic. The mean labial
infiltration pain rating was 17 + 8 mm, while the lingual was 16 + 16 mm. These ratings
also were considered “mild” pain on the 100-mm VAS (though the standard deviation of
the lingual injection included “moderate” pain). The authors did not differentiate
between stages of injection, nor did they use a 170-mm VAS. Direct comparisons cannot
be made to numerical values, but comparative results were found for the categorical pain
(i.e. “mild” pain was noted for both studies). Therefore, it appears that with or without
the use of topical anesthetic, the level of pain for these studies is consistent with our
results for mandibular labial and lingual needle penetration. In order to determine
whether topical anesthetic has any effect on needle penetration pain for mandibular
anterior infiltrations, a future study would need to directly compare the use of topical
anesthetic to the use of a placebo or no topical anesthetic.
“Since the pain experienced during an injection is more than a simple nociceptive
sensation, psychological factors may also influence the efficacy of topical anesthetics.
While some research indicates that the use of topical anesthetic would not significantly
decrease the discomfort associated with an injection (125, 129), Martin et al. (128) found
that if the patient thought they were receiving topical anesthetic, pain ratings for an
injection were lower than for those patients not believing they received a topical
anesthetic.”(27) Nakanishi et al. (131) found that, compared with placebo, topical
anesthesia significantly reduced needle insertion pain for the mandibular canine, but no
significant difference was found in the posterior. Due to the lower pain thresholds
discovered and the significant effect of topical in the anterior mandible, the authors
suggest use of topical in mandibular anterior teeth. If there is a physiologic or
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psychologic effect produced by the use of topical anesthetic, it follows that the pain
ratings for needle insertion could have been higher had topical anesthetic not been used.
Pain on Needle Placement
Data for the mean placement pain ratings for Group 1 and Group 2 are reported in
Table 2. The number and percentage of pain ratings by category (“none”, “mild”,
“moderate”, or “severe”) are presented in Table 4 for needle placement. Data for needle
placement pain ratings is reported in Appendix H. Data was statistically analyzed for
both groups by location (labial and lingual) and within groups by gender for needle
placement. For Group 1, labial needle placement resulted in a mean pain rating of 48.8
mm (“mild” pain), compared to 52.5 mm (“mild” pain) for Group 2. Both mean values
were in the “mild” pain category. For Group 1, lingual needle placement resulted in a
mean pain rating of 40.0 mm (“mild” pain), compared to 44.1 mm (“mild” pain) for
Group 2. Both mean values were in the “mild” pain category. For Group 1, seventy-two
percent of the labial pain ratings were in the none-to-mild category while 28% were in
the moderate-to-severe category (Table 4). For Group 2, sixty-six percent of labial pain
ratings were in the none-to-mild category while 34% were in the moderate-to-severe
category (Table 4). For Group 1, eighty-three percent of the lingual pain ratings were in
the none-to-mild category while 17% were in the moderate category (0% “severe”)
(Table 4). For Group 2, seventy-three percent of lingual pain ratings were in the none-to115
mild category while 27% were in the moderate-to-severe category (Table 4). Statistical
analysis of needle placement pain ratings found no significant differences between the
two groups for location and gender (Table 2). Females reported a higher mean pain
rating for Group 2 labial injections, resulting in a “moderate” pain rating, versus a “mild”
pain ranking for Group 1. Due to the large standard deviations (+ 35.5 mm for Group 1
and + 34.4 mm for Group 2), these means are not statistically different or clinically
relevant, though the categorical analysis reveals a higher ranking for Group 2. When
evaluating the gender differences in pain ratings during needle placement, no differences
(p>0.05) were found between males and females within either Group 1 or Group 2 (Table
2). Because all injections were given by the principal investigator, operator difference
within the current study would not be a factor. But when comparing between our study
and other studies, operator differences can be a factor in pain differences.
Pabst (27) and Robertson et al. (14), in studies of mandibular posterior
infiltrations of articaine, reported needle placement values similar to, although lower than
our study (34.3 mm and 32.7 mm, respectively). All values were in the “mild” pain
category and there were no significant differences between the two solutions. The studies
by Kanaa et al. (18), Corbett et al. (88), and Meechan and Kanaa (22) evaluated overall
pain of injection, but did not specify pain during each phase of injection. Similarly, Nist
et al. (6) did not distinguish between the phases of needle insertion and needle placement.
Instead, subjects in their study rated the entire injection in two phases called “needle
placement” and “solution deposition.” For this reason, pain values for needle placement
cannot be compared with these studies.
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The mean pain values for needle placement, while still in the “mild” category,
were higher than reported values for needle placement found other studies (13, 25, 27)
(Table 2). “During needle placement, the needle penetrates muscle tissue and fascia until
bone is contacted. The minor trauma to muscle and fascia can result in pain. The
severity of the pain reported can be dependent on the subject’s pain tolerance, the
subject’s expectations of pain, the manner in which the practitioner executes the
injection, and possibly the design of the needle bevel used for the injection (184).”(171)
Our study differed from Pabst (27) and Robertson (25), in that the subjects had two
separate sites for tissue trauma (labial and lingual). The labial and lingual combination
would potentially double the area of trauma compared with Robertson’s single buccal
infiltration (25). The difference between traumatizing the same location twice, as in
Pabst study (27) and traumatizing two separate locations may be significantly different.
Because our labial and lingual infiltrations (Group 1) traumatized anterior tissues and
studies (131, 185) show that the anterior mandible differs from the posterior mandible,
the pain experienced from our injections may be truly greater than those of posterior
studies. Ultimately, there may be a combination of anatomic differences, duplicitous
trauma, and/or population differences that could have influenced patient’s pain responses.
Further research would need to be done to verify this. Steinkruger et al. (171) attempted
to reduce this pain by investigating the pain on injection of a one-stage versus a two-stage
injection technique with the IAN block. In the two-stage injection technique, 0.4 mL of
anesthetic was deposited just under the mucosa and allowed to sit for 5 minutes. The
remaining anesthetic was then deposited at the target site. A statistically significant
difference was found between the two techniques during needle placement; however, it
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was the two-stage injection that was found to be more painful (171). Further study would
be needed to determine if a two-stage injection technique could help reduce the pain of
needle placement for mandibular infiltration injections.
Pain on Solution Deposition
Data for the mean solution deposition pain ratings for Group 1 and Group 2 are
reported in Table 2. The number and percentage of pain ratings per category (“none”,
“mild”, “moderate”, or “severe”) are presented in Table 5 for solution deposition.
Solution deposition pain ratings for the current study are reported in Appendix H. Data
was statistically analyzed for both groups by location (labial and lingual) and within
groups by gender for deposition. For Group 1, labial deposition of 1.8 mL of 4%
articaine with 1:100,000 epinephrine resulted in a mean pain rating of 61.5 mm,
compared to 70.4 mm for Group 2. Labial mean values for both groups were in the
“moderate” pain category. For Group 1, lingual deposition of 1.8 mL of 4% articaine
with 1:100,000 epinephrine resulted in a mean pain rating of 45.4 mm, compared to 44.6
mm for the mock injection in Group 2 (Table 2). No statistical pain difference was found
between receiving a full lingual cartridge of articaine (Group 1) versus receiving none
(Group 2 – mock lingual injection). Lingual mean values for both groups were in the
“mild” pain category. For Group 1, fifty-seven percent of the labial pain ratings were in
the mild category (0% in “none”), while 43% were in the moderate-to-severe category
(Table 5). For Group 1, seventy-four percent of the lingual pain ratings were in the noneto-mild category, while 26% were in the moderate-to-severe category (Table 5). For
Group 2, forty-three percent of the labial pain ratings were in the mild category (1% in
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“none”), while 56% were in the moderate-to-severe category (Table 5). For Group 2,
eighty-one percent of lingual pain ratings were in the none-to-mild category while 19%
were in the moderate-to-severe category (Table 5). Statistical analysis of solution
deposition pain ratings found no significant differences between the two groups by
location. For the labial injections, these statistically similar findings were anticipated
since both groups received equivalent volumes of anesthetics. When evaluating the
gender differences in pain ratings during solution deposition, no differences (p>0.05)
were found between males and females within either Group 1 or Group 2 (Table 2).
Though it was not in reported in the tables, the means for the labial depositions (61.5 mm
for Group 1 and 70.4 mm for Group 2) were significantly higher than the lingual
deposition (45.4 mm) of Group 1 (p<0.0001). Overall for location (labial versus lingual),
deposition pain was consistently reported as statistically (p<0.0001) and categorically
(“moderate”) higher with labial injections (Group 1 and Group 2) compared to the lingual
injection (Group 1 only).
For a lingual (Group 1) versus a mock lingual injection (Group 2), no statistically
significant difference was found. This was not anticipated. The subjects perceived pain
on deposition though no solution was deposited during the Group 2 “deposition”. The
“mild” pain reported for no deposition could be from patient expectations and uncertainty
from a relatively uncommon approach (i.e. lingual injection) or from the previous pain
experience (i.e. the labial injection). Although Nakanishi et al. (131) compared anterior
versus posterior mandibular topical anesthetic efficacy for needle insertion only, they
concluded that if pain is felt prior to a subsequent stage of injection, anxiety about further
treatment is to be expected. Since the pain experience is more than a simple nociceptive
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sensation, psychological factors may influence the subject’s reaction to the lingual
injection. “Many psychological factors such as anxiety, fear, trust, perceived control over
the painful stimulus, interpretation of the painful situation, personality, and placebo
treatments, influence pain (128). Kincheloe et al. (129) studied the correlation of the
expectancy of pain, the use of topical anesthetic, and the perception of pain in the dental
injection. They included two experimental groups and 2 control groups in their study.
The experimental groups received topical anesthetic and the control groups received a
placebo but only one subgroup from each group were given instructions (that is, they
were told that they were given a topical anesthetic that would numb them and make the
injection a lot less painful. The other subgroup from each group was not given any
instructions. The results showed no significant pain reduction with the use of topical
anesthetic versus a placebo. However, when the subjects were analyzed according to
their expectation of pain, the subjects with high pain expectancy experienced a
statistically higher (p<0.05) amount of discomfort than those with low pain expectancy.
Because the patients in their study, with high expectancy of pain, fulfilled their
expectations and experienced a more painful injection than those with lower expectations,
they concluded that good patient management dictates that a dentist should attempt to
assure the patient that everything possible is being done to make them comfortable.”(27)
Because deposition resulted in “moderate” pain for 43-55% of subjects receiving a labial
injection of articaine (as seen in Table 5), expectations of a subsequent painful experience
may elevate patients’ pain ratings for a mock injection. This psychological expectancy of
pain may also have been a factor in the true lingual injection as well, because whether a
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mock or true lingual deposition occurred, the lingual means and standard deviations for
both groups were almost identical (Table 2).
Another possible explanation of pain ratings for the mock lingual deposition
could be from a nocebo reaction. When a “subject's symptoms are worsened by the
administration of an inert, sham, or dummy treatment” (186) this has been referred to as a
nocebo reaction. The combination of anticipated pain and the insertion from the mock
lingual infiltration may have resulted in a nocebo reaction with the mock deposition.
“Similar findings of the nocebo effect have been reported in other research. In a
study by Long et al. (187), a functionless machine was tested in 58 patients with chronic
pain. Five patients discontinued treatment before finishing because the sham therapy
worsened their pain. Eleven percent of patients undergoing the sham trials experienced a
significant increase in pain. Oftedal et al. (188) studied the effects of radio frequency
fields given off by mobile phones and their effects on head pain. Seventeen subjects
participated in a double-blind, randomized provocation study with cross-over design.
Radio frequency fields increased subjects’ pain or discomfort by 10.1 mm on a Visual
Analogue Scale. Sham sessions resulted in pain increases of 12.6 mm. While the authors
did not show any differences between the two “fields,” this study does show that subjects
receiving sham treatment can experience increases in pain. The authors attributed the
increase in pain to the nocebo effect. Schweiger and Parducci (189) found that more than
two-thirds of 34 sampled college students reported mild headaches when told that a
(nonexistent) electric current was passing through their heads. These headache reports
appeared when the headache-producing effects of the current were emphasized or
mentioned as only a potential side effect. The authors concluded that focusing on pain
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may itself be a cause of pain.”(186) Thus, if subjects in our study expected pain then
they could also have a possible increase in pain though no deposition of anesthetic
occurred. The findings of Schweiger and Parducci (189) are similar to our study.
Because the average subject had experienced “moderate” pain with the labial infiltration
moments prior to the lingual mock infiltration, one could assume that subjects were
expecting pain and or focusing on pain as a potential side effect of the following lingual
infiltration. This could potentially induce patients to have a nocebo reaction to the mock
infiltration, resulting in a significant pain rating on the VAS for the mock injection.
Another reason for rating pain for all stages of injection (including a mock
placement and deposition) could be a subject’s inability to differentiate between the pain
from the initial insertion or the mock deposition. “If one part of the injection was
particularly painful, the subject may have been inclined to report their pain ratings based
on a comparative analysis to the other injection stages rather than as a separate report
based on each event individually (184). Comparative analysis by the subject may have
been prevented if we had measured pain immediately after each phase of the injection.
Additionally, some subjects may have been experiencing significant lingering discomfort
from the needle placement phase of the injection and were unable to distinguish the
solution deposition phase from the needle placement phase because of this lingering
needle placement pain. Pain resulting from trauma to a structure does not generally
disappear entirely the moment the trauma has ended.”(27)
Both facts that the labial injection was statistically more painful (p<0.0001) and
that the lingual insertion may have lingering pain can present subjects with difficulty in
differentiating painful stimuli. Possibly alternating primary injections between labial and
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lingual will provide some more accurate “mock” pain scores, versus always having to
rate a lingual (true or mock) injection after a labial injection (which on average was
“moderately painful”). Future design of a similar study could include a group of patients
receiving lingual injections prior to labial injections in order to determine if physiological
differences or psychological expectations have such an effect. Assuming that
expectations do condition patient responses, when implementing the lingual injection,
clinicians may need to advise patients that they are doing everything possible to make
their experience as painless as possible.
The major statistical difference in pain noted for stages of injections was that both
males and females rated labial deposition as significantly more painful (p<0.0001) than a
lingual injection (Group 1). For Group 1, labial deposition of 1.8 mL of 4% articaine
with 1:100,000 epinephrine resulted in an overall mean pain rating of 61.5 mm, compared
to 70.4 mm for Group 2. For males in Group 1, the mean labial pain rating for deposition
was 58.3 mm, while the mean lingual pain rating was 42.5 mm. For females in Group 1,
the mean labial pain rating for deposition was 65.1 mm, while the mean lingual pain
rating was 48.6 mm. For the labial injection, both male and female mean pain ratings
were in the “moderate” category. For the lingual injection, both male and female mean
pain ratings were in the “mild” category. Nakanishi et al. (131) showed that there may be
a lower pain threshold related to the labial aspect of the anterior mandible when
compared to the posterior. The authors did not investigate the lingual pain thresholds.
Our study could indicate that higher pain thresholds could exist lingual to anterior teeth.
Further studies would be needed to explore this idea. Another possibility could be
anatomical differences. Arens et al. (185) noted that infections from the lower incisors
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usually break through the labial plate, probably due to the thinner labial plate (1.5 - 2
mm) compared to the thicker lingual plate (3 – 4 mm) at the apices of the teeth. In
relation to the labial infiltration, the authors also noted that, “the mentalis muscles arise
from the mandibular alveolar process near the apexes of the central and lateral incisors.
Their origin is higher [more superior] than the fornix of the vestibule thus making it more
shallow upon contraction.” (185) Since our labial protocol was to inject at the apices of
the lateral incisors, this would indicate a potential of injecting a bolus of anesthetic
solution into the mentalis muscle. Also if the patient contracted the mentalis muscle
during this scenario, the possibility of a higher pain response could occur due to a more
constricted injection site. When indicating pathways of infection from lower incisors,
Arens et al. (185) notes that, “Because of the low attachment of the mylohyoid muscle at
its anterior border, lingual cortical plate perforation from the incisor teeth usually
localizes in the sublingual space after perforation of the periosteum.” They also indicate
that only on rare occasions does infection perforate below the mylohyoid attachment
(185). The possible deduction from these findings is that the majority of lingual muscle
attachments are inferior to the apices of incisors, indicating that in general our lingual
injections would have been administered into the loose connective tissue of the lingual
vestibule and not into muscles. Because this sublingual space should exhibit greater
elasticity when compared to the possible mentalis space injection, the injected bolus of
lingual anesthetic could potentially be less painful than the labial infiltration. This could
help to explain why lingual infiltrations were statistically less painful than labial
infiltrations. This explanation would not exclude the potential for an order bias related to
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the labial infiltration always occurring first and patients recording labial pain first on the
VAS.
Though of no statistical difference, it is interesting to note that for both groups in
our study, females reported higher levels of pain than males did during solution
deposition (Table 2). Females reported overall higher mean pain ratings for each phase
of the injection, but the differences were not statistically different. Robertson (25) and
Pabst (27) reported similar results. Also, this difference is consistent with the findings of
Liddel and Locker (176), Fillingim et al. (177), and Keogh et al. (183) in terms of sex
differences in reporting pain as discussed previously. Yet overall, our statistical analysis
did not find the higher mean ratings of females to be of consequence.
Nist et al. (6) showed pain on deposition to be “mild” for incisive nerve blocks
over the mental foramen. Nist et al. (6) used a 27-gauge needle to deposit 1.6 mL of
anesthetic solution within the mental foramen over a period of two minutes following the
initial deposition of 0.2 mL of solution (a two stage injection technique). A mean pain
value of 11.1 mm on a 100-mm VAS for solution deposition was reported, which is
consistent with “mild” pain. Because a 170-mm VAS was used in our study, it is difficult
to compare the results. However, using proportional analysis, this score would represent
a rating of 18.9 mm on our scale. When comparing to our findings, the average
deposition pain score was 61.5 mm and 70.4 mm for a labial infiltration, respective to
groups. These values are significantly higher than those found for the incisive nerve
block.
Pabst (27) found a significant difference in pain ratings for solution deposition in
the primary injection for both groups; however no significant differences were found for
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needle insertion or placement for either group. Pabst (27) found that eighty-eight percent
of deposition pain ratings were in the none-to-mild category while 12% were in the
moderate-to-severe category for buccal infiltrations with articaine. For the posterior
buccal infiltrations, mean values were in the “mild” pain category. “This is consistent
with the findings of studies by Kanaa et al. (18), Corbett et al. (88) and by Robertson et
al. (14), in which injections of 4% articaine with epinephrine were associated with only
“mild” discomfort. Kanaa et al. (18) and Corbett et al. (88) used a 30-gauge needle in
both studies and deposited the 1.8 mL of anesthetic solution over a period of
approximately 30 seconds. Both Robertson’s study (25) and the current study used a 27gauge needle, and the cartridge of anesthetic was deposited over a period of
approximately 60 seconds. Robertson found a mean solution deposition pain rating of
36.4 mm for a buccal infiltration with articaine (25). “In trying to compare these studies,
it appears that the needle gauge (30- vs. 27-gauge) and speed of injection (30- vs. 60seconds) may not play a role in solution deposition pain in mandibular buccal
infiltrations.”(27) However, a direct comparison is difficult due to differences between
the studies in pain measurement techniques and injection site difference (anterior versus
posterior).
The fact that labial mean values for both groups were in the “moderate” category
shows a difference from most other posterior and anterior studies. Meechan (22),
Robertson et al. (14), Pabst et al. (87), all found an average of “mild” pain in posterior
buccal infiltrations with articaine. Meechan et al. (22) found mild pain averages,
regardless of buccal or lingual infiltrations. Meechan and Ledvinka (13) found no
differences in pain ratings by location (labial or lingual) of anterior teeth when using 0.5
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mL of 2% lidocaine with 1:80,000 epinephrine. The pain average was also reported as
“mild” pain, with only 3 out of 24 (12.5%) reporting moderate discomfort on injection.
The current study cannot be directly compared to these studies because of either different
locations for testing (i.e. posterior teeth) or different anesthetics (i.e. lidocaine).
Evans et al. (119) in studying maxillary anterior infiltrations found moderate pain
ratings for articaine infiltration injections. Evans et al. (119) found the mean VAS pain
value for solution deposition to be 54.9 mm for anterior labial deposition and 39.9 mm
for the posterior buccal deposition, but this difference was not statistically significant.
The anterior average pain rating (54.9 mm) and category (moderate) is quite similar to
that found for our anterior labial deposition (61.5 mm to 70.4 mm mean VAS values and
“moderate” category). When compared to other solutions and locations, the possible
causes for these differences noted in deposition pain with articaine in anterior infiltrations
could be the pH of the drug (158), anatomic differences (16), and/or molecular
differences (54).
“Malamed (158) states that the primary cause of the “mild burning sensation”
often experienced with the deposition of the anesthetic solution may be its acidic pH.
Malamed measured the pH of various anesthetic solutions and found that the pH of
lidocaine with 1:100,000 epinephrine ranges from 3.3 to 5.5, and the pH of articaine with
1:100,000 epinephrine is 5.0. The pH of the 4% articaine with 1:100,000 epinephrine
solution used in this study was 5.0 (73).”(119) Also, Wahl et al. (190) found the pH of
lidocaine with 1:100,000 ranges from 4.0 to 4.5, and articaine with 1:100,000 epinephrine
ranges from 3.5 to 4.5. Using a ten-point scale, Wahl et al. (190) found no difference in
injection pain between these articaine and lidocaine solutions, though each resulted in
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more pain than 4% prilocaine without epinephrine. “This was true for all three injection
locations studied: maxillary buccal infiltration, palatal infiltration, and inferior alveolar
nerve block. The lack of epinephrine in prilocaine would increase the pH and therefore
cause less of an acidic burning sensation to the tissues. Consistent with these results,
Robertson (25) found no significant differences between the articaine and lidocaine for
solution deposition pain ratings.”(27) “Several studies (163, 191) have examined the
effect of a buffered lidocaine solution on pain of solution deposition and found that it
failed to significantly reduce pain scores. This suggests that pH may not have as big a
role in deposition pain as previously thought.”(119) Since the pH of articaine is similar
to or higher than the pH of lidocaine, it is more likely that something other than pH
caused pain upon injection.
Haas et al. (16) suggested that anterior and posterior sites may differ in cortical
bone thickness, affecting penetration of anesthesia, but the authors couldn’t substantiate a
clinical difference. Nakanishi et al. (131) found that, compared with placebo, topical
anesthesia significantly reduced needle insertion pain for the mandibular anterior area,
but no significant difference was found in the posterior. The authors also discovered a
significantly lower pain threshold for labial needle penetration when compared to
posterior buccal insertions. The study did not test deposition pain. Nakanishi et al. (131)
suggests that the lower pain threshold could be the presence of smaller receptive fields
(touch points and pain spots) apparent in the anterior labial mucosa. The anatomical
difference of the anterior labial mucosa and underlying muscles and fascia may increase
pain sensation, resulting in higher pain ratings (185).
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“A recent study by Gordon et al. (192) found that bupivaine upregulated COX-1
and COX-2 production and caused an increase in pain. However, this pain was noted at
24 hours after the injection and not immediately upon injection. The authors were unable
to explain this phenomenon but suggest that the chemical structure of an anesthetic may
have an influence on tissue reactions and may influence solution deposition pain (192). It
is possible that there is something inherent to the structure of articaine that causes pain.
Further study is needed to investigate this.”(119)
Evans et al. (119) found significant pain differences between the lidocaine and
articaine solutions upon deposition, but no significant pain differences when comparing
the two solutions by anterior or posterior maxillary injection. Nakanishi et al. (131)
found physiological differences in pain for anterior injection sites. Gordon (192) found
chemical differences in anesthetic solutions which may influence deposition pain. Both
the current study and Evans’ (119) study showed anesthetic deposition pain as
“moderate.” Although the difference between anterior and posterior was not statistically
significant in Evans’ study, categorically pain for anterior teeth was found to be higher
than posterior teeth with an articaine solution.
Another possible consideration for pain etiology is speed of injection. If there are
anatomical differences between location (labial versus lingual and anterior versus
posterior), and assuming the anterior labial injection is more painful utilizing articaine,
the reduction in speed of injection may decrease pain. This study and others (19, 25, 27,
119) performed here in the Division of Endodontics at The Ohio State University have
used a rate of injection of approximately 1 mL every 30 seconds, or 1.8 mL every minute.
Variations in rate of injection, differences in subjects’ pain thresholds, injection location
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(in this study a mandibular labial infiltration), and differences in solution composition
could all account for differences in pain ratings during solution deposition. In our study,
each subject recorded pain ratings for all three stages after both injections were complete
(labial and lingual). The reason patients had to wait for both injections before recording
pain was due to the blinding of the experiment (i.e. subjects were blindfolded during both
injections). Also, because two injections were given immediately, time for patient
evaluation and recording of their pain from the first injection would have delayed and
compromised pulp testing commencement and ultimately onset of anesthesia. If one part
of the injection was particularly painful (i.e. labial injection), the subject may have been
inclined to report their pain ratings based on a comparative analysis to the other injection
stages rather than as a separate report based on each individual stage and site of injection.
Comparative analysis by the subject may have been prevented if we had measured pain
immediately after each phase of the injection, but this would have potentially
compromised further, more critical data.
It is apparent from the previously mentioned studies that moderate to severe pain
is possible during an incisive nerve block (6) using lidocaine with epinephrine, and
during a buccal infiltration injection (18, 26, 88, 119) using articaine with epinephrine
and lidocaine with epinephrine. This was confirmed in our study with labial and lingual
infiltration injections of articaine. “Malamed (158) suggests slowing the rate of
anesthetic deposition to 1 mL in not less than 60 seconds, or 1.8 mL in about 2 minutes.
Steinkruger et al. (171) hypothesized that using a two-stage injection technique could
minimize the severity of the pain experienced. However, no significant difference was
found during solution deposition between the two techniques (171).”(27)
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“It has been suggested that buffering anesthetic solution to make the pH similar to
that of the tissue may help to reduce solution deposition pain, but attempts to buffer an
anesthetic solution to reduce deposition pain have not produced significantly better
results. Primosch and Robinson (191) buffered a 2% lidocaine with 1:100,000
epinephrine solution with 8.4% sodium bicarbonate and recorded solution deposition pain
for maxillary labial and palatal infiltrations. They were unable to find a significant
difference for solution deposition pain between the buffered and unbuffered solutions.
Whitcomb (193) buffered a 2% lidocaine with 1:100,000 epinephrine solution with 8.4%
sodium bicarbonate, and tested its effect during an inferior alveolar nerve block. The
buffered solution did not significantly decrease pain intensity during solution deposition
in comparison to the unbuffered solution.” (27)
In summary, the two groups used in the current study did not show a statistically
significant difference in pain intensity per stage of injection. Labial solution deposition
in males and females and labial needle placement for females (Group 2) were the highest
reported means, representing the “moderate” pain category. All other stages of injection,
whether labial or lingual, represented an average of “mild” pain. Moderate-to-severe
pain during needle insertion and placement, and during lingual solution deposition, was
experienced by some subjects but occurred much less frequently than none-to-mild pain
for both groups. Only labial deposition in Group 2 represented a greater percentage of
moderate (51%) to severe (5%) pain ratings compared to none-to-mild. Gender did not
statistically influence pain ratings during any stage of injection, but females did
consistently report higher pain levels during each stage of injection (though not
statistically significant).
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ANESTHETIC EFFICACY
Several factors, such as frequency of pulpal anesthesia, anesthetic success,
anesthetic failure, and onset of anesthesia should be considered when evaluating
anesthetic efficacy.
Frequency of Pulpal Anesthesia
Figure 1 and Table 6 illustrate pulpal anesthesia (% 80/80) of the mandibular
lateral incisor throughout the testing period, which ranged from the lowest at 23% (min
1) to the highest at 96% (min 13) with Group 1 (labial and lingual articaine injection) and
from 7% (min 58) to 73% (min 16) with Group 2 (labial articaine and mock lingual
injection). The double injection (Group 1) reached peak anesthesia at minute 28, stayed
above 75% (%80/80) until minute 40, and decreased to 61% by the end of testing. The
single injection (Group 2) reached peak anesthesia at minute 16, never reached 75%
(%80/80), and steadily declined to 7% by the end of testing. At each time period from
minute 4 to minute 58, there was a significantly (p < 0.05) higher percentage of 80/80
readings in Group 1 compared to the readings in Group 2. Greater than 75% of patients
reported 80/80 readings from minute 7 to 40 for Group 1, while the highest percentage of
patients reporting 80/80 readings was 73% for Group 2, never reaching 75%. In Group 2,
for more than half of the time, less than 50% of patients reported pulpal anesthesia, while
in Group 1 only at time period 1 did less than 50% of patients report pulpal anesthesia.
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For both groups, at least some subjects sustained 80/80 readings for the entire test period
(i.e. there were no time points with zero percent 80/80 readings).
Figure 2 and Table 7 illustrate pulpal anesthesia (% 80/80) of the mandibular
central incisor throughout the testing period, which ranged from the lowest at 53% (min
1) to the highest at 95% (min 19) with Group 1 (labial and lingual articaine injection) and
from 7% (min 58) to 78% (minutes 13 and 16) with Group 2 (labial articaine and mock
lingual injection). The double injection (Group 1) reached peak anesthesia at minute 10,
stayed above 75% (%80/80) until minute 40, and decreased to 56% by the end of testing.
The single injection (Group 2) reached peak anesthesia at minute 13, and stayed above
75% (%80/80) from 10-16 minutes, and steadily declined to 7% by the end of testing. At
each time period from minute 4 to minute 58, there was a significantly (p<0.05) higher
percentage of 80/80 readings in Group 1 compared to the readings in Group 2. Greater
than 75% of patients reported 80/80 readings from minute 4 to 40 for Group 1, while
Group 2 only reported 80/80 readings higher than 75% for 3 test periods (10, 13, and 16
minutes). In Group 2, for more than half of the time, less than 50% of patients reported
pulpal anesthesia. In Group 1, at no time period did less than 50% of patients report
pulpal anesthesia. Again for both groups, at least some subjects sustained 80/80 readings
for the entire test period (i.e. there were no time points with zero percent 80/80 readings).
Figure 3 and Table 8 illustrate pulpal anesthesia (%80/80) of the mandibular
canine throughout the testing period, which ranged from the lowest at 29% (min 2) to the
highest at 92% (min 20) with Group 1 (labial and lingual articaine injection) and from
12% (min 58) to 73% (min 14) with Group 2 (labial articaine and mock lingual injection).
The double injection (Group 1) reached peak anesthesia at minute 17, stayed above 75%
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(%80/80) until minute 41, and decreased to 49% by the end of testing. The single
injection (Group 2) reached peak anesthesia at minute 14, never reached 75% (%80/80),
and steadily declined to 12% by the end of testing. At minute 8 and from minute 17 to
minute 59, there was a significantly (p<0.05) higher percentage of 80/80 readings in
Group 1 compared to the readings in Group 2. This tooth appears to have taken
additional time for the effects of the lingual injection to significantly affect pulpal
anesthesia since differences were not consistently observed until minute 17, as compared
to both the incisors reaching significant differences by minute 4. Greater than 75% of
patients reported 80/80 readings from minute 8 to 41 for Group 1, while the highest
percentage of patients reporting 80/80 readings was 73% (min 14) for Group 2. In
Group 2, for more than half of the time, less than 50% of patients reported pulpal
anesthesia, while in Group 1 only at time periods 2 and 59 did less than 50% of patients
report pulpal anesthesia. Again for both groups, at least some subjects sustained 80/80
readings for the entire test period (i.e. there were no time points with zero percent 80/80
readings).
In general, all teeth in Group 1 reached 75% of 80/80 readings by the same testing
period (test period 3 or minute 7 for incisors and minute 8 for canine). The central
incisor had already surpassed 90% of 80/80 readings by minute 4, while the lateral
incisor did not reach this level until 10 minutes. The central incisor had a similar
percentage of 80/80 readings compared to the lateral incisor, though the injection was
given over the lateral.
The maximum percentage of 80/80 readings for each of the three test teeth
occurred from 13 to 20 minutes for Group 1 and from 14 to 16 minutes for Group 2
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(Tables 6-8). After these times, fewer teeth were achieving anesthesia onset, and instead
a gradual loss of anesthesia occurred over time. Faster loss of anesthesia (i.e. greater
negative slopes after the maximum percent of 80/80 readings) was noted with Group 2,
compared to Group 1 (Figures 1-3).
As discussed earlier, it is assumed that most dental procedures will take one hour
to complete. Therefore, it would be advantageous for the percentages of teeth with
profound anesthesia to be as high as possible during this time to avoid pain and
complications during treatment. Infiltration anesthesia does not typically last for one
hour. The frequency of 80/80 readings for all teeth was greater than 75% for more than
30 minutes of the study (at least min 8 to 40), with maximum frequency of 80/80
readings reaching from 92% to 96% (Tables 6-8). Haas et al. (16), using either 1.5 mL
4% articaine with 1:200,000 epinephrine or 1.5 mL 4% prilocaine with 1:200,000
epinephrine labial to the mandibular canine and contralateral canine, never found a
frequency of 80/80 readings reaching 75% in the 25 minute test period, with a maximum
frequency of 60-65% for the canine. This would be comparable to our Group 2 canine in
which at no time point did the frequency of 80/80 readings reach 75%, with a maximum
of 73% noted. This is the only current study on articaine infiltrations of mandibular
anterior teeth. Yonchak et al. (21), using 1.8 mL of 2% lidocaine 1:100,000 epinephrine
labial or lingual to the lateral incisor, never established a 75% frequency of 80/80
readings for subjects in a 60 minute test period, with the maximum frequency of 80/80
readings reaching only 50% (for the lateral incisor). This would be more comparable to
our Group 2 results for the lateral incisor, in which we found the labial injection of
articaine never reaching a 75% frequency of 80/80 reading for subjects, with a maximum
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frequency of 73%. Meechan and Ledvinka (13), using 0.5 mL of 2% lidocaine with
1:80,000 epinephrine both labial and lingual to the central incisor, found a 75%
frequency of 80/80 readings for 16 minutes (from 8 to 24 minutes), with a maximum
frequency of 80/80 readings of 83%. Their study (13) only incorporated 12 teeth in a test
period of only 30 minutes. By 28 minutes, a maximum of 67% reported 80/80 readings,
compared to 93% in our Group 1 central incisor. Their study (13) cannot be directly
compared to the current study because the anesthetic solutions and volumes differ
significantly. Yet the findings of Group 2 (labial articaine infiltration) show similar
trends for frequency of 80/80 readings when compared to labial infiltrations with similar
volumes of articaine and lidocaine. But none (13, 16, 21) of the aforementioned anterior
infiltration studies show comparably high frequencies as demonstrated in Group 1 (labial
and lingual articaine infiltrations) of the current study.
Previous studies by Robertson (25) and Pabst (27) demonstrated a decline of
pulpal anesthesia over 60 minutes following a single mandibular buccal infiltration
injection. Robertson (25) and Pabst (27) demonstrated a frequency of 80/80 readings for
the first molar (i.e. the test tooth, over which the anesthetic was deposited), respectively,
as follows: 63.3% and 39.5% at 30 minutes, 36.7% and 20.9% after 45 minutes, and only
18.3% and 15.1% at 60 minutes. Though Pabst had higher results with the double
injection, her repeated infiltration took place 25 minutes after the initial and does not
allow a direct comparison to our labial and lingual infiltration frequencies within the 60
minute test period. In our study, the frequency of 80/80 readings for the lateral incisor
(the test tooth) with a labial and lingual infiltration versus a labial infiltration only
respectively, was as follows: 92.7% versus 62.2% at 31 minutes, 74.4% versus 19.5% at
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46 minutes, and 61.0% versus 7.3% at 58 minutes. Therefore, using only a labial
infiltration, our Group 2 frequency of anesthesia followed a similar pattern to Pabst and
Robertson’s studies over the test period, though at 58 minutes our success was notably
lower (7% versus 15-18%). This late apparent difference in anesthetic frequency may be
related to faster penetration through a less dense labial cortical plate, as was suggested by
several authors (83, 85, 158). Yet overall, when a labial and lingual infiltration were
given, the percent of 80/80 readings at 30, 45, and 60 minutes in our study (93%, 74%,
and 61%) was significantly higher than Pabst (27) and Robertson (25) (40-63%, 21-37%,
and 15-18%). This higher success appears to be due to a higher volume of anesthetic
and the possibility of augmentation of the anesthetic’s effect.
The current study showed a significantly greater efficacy for pulpal anesthesia
when a second cartridge of articaine was given lingual to the test tooth, immediately
following a labial articaine injection (see Figures 1 to 3). When this method was
performed on Group 1, a higher incidence of pulpal anesthesia was seen for each toothtype tested for almost the entire test period. With frequency of pulpal anesthesia reaching
greater than 75% for up to 40 minutes, it appears that for most dental appointments
lasting less than 40 minutes, this method could be considered for anesthesia in the
anterior mandible.
“The unique chemical structure of articaine, with its thiophene ring and ester side
chain, may allow for enhanced osseous penetration of the anesthetic. Its plasma protein
binding is approximately 95% while lidocaine’s is approximately 65%. The lipid
solubility ratio of articaine to lidocaine is approximately 3 to 8 (54). If the molecular
structure or higher concentration of articaine results in more anesthetic diffusing through
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the mandibular cortical plate, and if this tends to occur in a certain anteroposterior
location of the mandible due to differences in cortical plate thickness or density, we
would expect to see a preference for anesthesia to occur in one tooth.”(25) For our study,
the central incisor appeared to have a similar preference for anesthesia to the lateral, over
which the anesthetic was given. This was found to be true with both groups using the 4%
articaine solution.
“If the anesthetic solution is able to diffuse through the cortical plate, the
thickness or density of an individual’s cortical plate would likely determine whether the
injection will be successful. This is supported by pediatric studies by Dudkiewicz et al.
(83) and Wright et al. (85) involving mandibular buccal infiltrations using 4% articaine.
They found that articaine was fairly successful in producing numbness in primary teeth,
presumably due to the relatively thin and more porous mandibular bone of children.
The pattern of pulpal anesthesia observed in this study suggests that the anesthetic
solution tends to diffuse anteriorly from the lateral incisor. Alternatively, diffusion
posteriorly (i.e. towards the canine) appears to be less (lower anesthetic success, as seen
in Table 9). For the combined labial and lingual articaine infiltrations (Group 1), the
canine experienced the least percentage of 80/80 readings equal to or greater than 90%
(only 6 minutes, from minute 17 to 23). For Group 1, the lateral incisor experienced
greater than 90% of 80/80 readings for 24 minutes (from 10 to 34 minutes). For Group 1,
the central incisor experienced greater than 90% of 80/80 readings for 21 minutes (from 7
to 28 minutes). With Group 2, the lateral incisor had the least amount of greater than
70% 80/80 readings (3 minutes, from 13 to 16 minutes), compared with 15 minutes and 9
minutes with the central incisor and canine, respectively. In this case, anesthetic may
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diffuse differently related to thickness of labial or lingual cortical plates. Apparently for
the Group 2 labial injections, it may be that diffusion is better over the central incisor,
when compared to the canine and the lateral incisor. This could indicate greater labial
cortical bone thickness over the lateral incisor and canine, compared to the central
incisor. Yet when a lingual infiltration was added, the lateral incisor (the tested tooth)
had greater frequency of anesthesia than the central, which had a greater frequency than
the canine. This could indicate thinner cortical plate areas lingual to the lateral,
compared with the canine and central incisor. Overall, anatomical barriers to anesthetic
diffusion could affect overall frequency of anesthesia, namely: mandibular tori; mentalis,
depressor anguli oris, and labii inferioris muscle attachment sites; and cortical bone
thickness relative to the injection site (185).
Overall, the pattern of pulpal anesthesia observed in this study suggests that the
anesthetic solution tended to diffuse more readily anterior to the lateral incisor, but less
readily towards the canine. This was also found to be true in posterior studies (25, 27).
If true, it may then diffuse into the mandible through the relatively thin cortical bone in
the more anterior region, possibly labial to the central incisors or at the symphysis.
“According to Malamed, (158) ‘The bone forming the buccal alveolar processes in the
anterior region (incisors) is usually less dense than that over the posterior teeth,
permitting infiltration (supraperiosteal) anesthesia to be employed with some expectation
of success.’”(25) Perhaps the density or thickness of bone labial to the incisors is less in
the anterior region, but more in the canine region, allowing a lesser degree of success to
be achieved in this area. Arens et al. (185) indicated no difference in the labial cortical
bone thickness over the apices of the canines compared to incisors, but they do note that
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“the depressors anguli oris and labii inferioris arise on the mandible near the apex of the
cuspid.” In our study, these muscle attachments may have played more of a role than
cortical bone thickness in restricting anesthetic flow to the canine when compared to the
incisors.
“A high concentration of anesthetic molecules in solution may be critical to
anesthetic efficacy if the anesthetic must diffuse through the cortical plate. If so, a 4%
articaine solution would be expected to have greater efficacy than a 2% lidocaine solution
for this type of injection. If a certain ratio of anesthetic molecules tends to diffuse
through the cortical plate, regardless of the type of anesthetic used and its particular
properties, then increasing the concentration of the injected anesthetic would result in a
proportional increase in the number of anesthetic molecules that will eventually be
present on the opposite side of the cortical plate (in the cancellous bone).”(25) The
significantly greater success in Group 1 (doubling the volume of the 4% concentration of
articaine) compared to Group 2 (single volume of 4% articaine) suggests that having an
equal concentration and volume of anesthetic labial and lingual at the target site
significantly increases efficacy of that solution penetrating the labial/lingual cortical plate
and incisive nerve. This finding cannot be compared to other anterior mandibular
studies, because none have incorporated a labial and lingual approach in the same test
period.
Another possibility is that the anesthetic solution enters the mental foramen after
diffusing posteriorly through the soft tissue. In this case, the premolars would be the
most likely to be anesthetized. These were not tested in the study. Adjacent teeth in
either direction may also be anesthetized, depending on how far the anesthetic solution
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diffuses after entering the mental foramen. “Tebo and Telford (194) and Mastuda (195),
in anatomical studies, reported the location of the mental foramen to be in the apical area
of the second premolar approximately 50% and 68% of the time, respectively. Phillips et
al. (196) found the foramen in line with the long axis of the second premolar 63% of the
time. When the foramen was mesial or distal to the long axis of the second premolar, it
was within 2 mm of the long axis.”(27) In general, the results of this study do not
support this as a possible mechanism.
Frequency of pulpal anesthesia is a useful statistic to predict the probability that a
given tooth in a given patient will be profoundly numb at a given time point. For
example, one could predict from our study that if a patient received a mandibular labial
infiltration adjacent to the lateral incisor with 1.8 mL of 4% articaine with 1:100,000
epinephrine 34 minutes later there would be a 39.0% chance that the patient's lateral
incisor would be numb. Yet if a patient received an identical mandibular labial
infiltration combined with a lingual infiltration adjacent to the lateral incisor with 1.8 mL
of 4% articaine with 1:100,000 epinephrine (totaling 3.6 mL), 34 minutes later there
would be a 90.2% chance that the patient's lateral incisor would be numb. Unfortunately,
no anesthetic solution tested in this or any other study has been shown to achieve 100%
predictable local anesthesia at any time point.
Anesthetic Success
Pulpal anesthesia was analyzed by using two definitions of success. The first
definition, Success #1, was defined as achieving the first of two consecutive 80/80
readings with the electric pulp tester within 10 minutes of the completed lingual injection
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for incisors, or within 11 minutes of the completed lingual injection for the canine, and
sustaining these readings continuously for at least 60-minutes. This definition is more
strict and excludes subjects who lost anesthesia and then regained it within the 60-minute
testing period (noncontinuous anesthesia), as well as those who were slow to achieve
pulpal anesthesia which lasted for the remainder of the testing period (slow onset). Using
the mandibular labial and lingual infiltration injections, Group 1 (1.8 mL labial and 1.8
mL lingual to the lateral incisor) and Group 2 (1.8 mL labial to the lateral incisor,
followed by a lingual mock infiltration at the lateral incisor apex) produced successful
pulpal anesthesia, respectively, as follows: 59.8% and 7.3% for the lateral incisors
(p<0.0001); 56.1% and 6.1% for the central incisors (p<0.0001); and 42.7% and 9.8% for
the canines (p<0.0001). Statistical analysis of anesthetic success found significantly
higher success rates for Group 1 for all three of the test teeth (Table 9).
The Success #1 results of the single labial injection (Group 2) of the current study
can be compared to several studies, though not directly. No studies to date have
compared a labial and lingual infiltration injection of articaine. Haas et al. (16, 20)
studied labial articaine infiltrations, but only utilized a 25 minute test period and a single
median pulp test reading of 80. Meechan and Ledvinka (13) studied lidocaine
infiltrations, with anesthetic success defined as our Success #2. No mandibular anterior
studies have been done with articaine which utilized a similar anesthetic success criterion
(Success #1). Clark et al. (3) evaluated the anesthetic efficacy of a combination of the
inferior alveolar nerve block with a labial or lingual infiltration in the mandibular anterior
teeth. Forty patients randomly received the following injection combinations: an IAN
block followed by a mock lingual and mock labial infiltration, an IAN block followed by
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a mock lingual infiltration and labial infiltration, an IAN block followed by a mock labial
infiltration and lingual infiltration. The standard IAN block was made using 3.6 mL of
2% lidocaine with 1:100,000 epinephrine, while the infiltration – injected over the apex
of the lateral incisor – utilized 1.8 mL of 2% lidocaine with 1:100,000 epinephrine. The
authors used a similar definition of success (anesthesia was considered successful when
two consecutive readings of 80 were obtained on the electronic pulp tester within 15
minutes and were sustained for 60 minutes). All patients experienced lip numbness with
the IAN blocks. When the labial infiltration was added, the lateral incisor’s success rate
was 62%. The authors did not study a combined labial and lingual infiltration added to a
block. For both the lateral and central incisor, the difference between the IAN block
alone (40% and 10%, respectively) and the IAN block plus labial infiltration (62% and
40%, respectively) was significant (p< 0.05). The inferior alveolar nerve block alone
(10-58%) was not effective in producing anesthesia in the anterior teeth. However, a
labial infiltration of lidocaine solution in combination with a conventional inferior
alveolar nerve block with the lidocaine solution did increase the success rate of pulpal
anesthesia from 40% to 62% in mandibular lateral incisors and from 10% to 40% in
central incisors, but no change was seen in mandibular canines (from 58% to 58%). In
the current study, utilizing no IAN block, a double infiltration of articaine solution
(Group 1) over the lateral incisor produced anesthetic success for 60% of lateral incisors,
56% for central incisors, and 43% for canines. Because the definitions of success are
relatively similar, our success (60%) of the lateral incisor compares almost exactly to
Clark’s (62%), though the techniques (double infiltration injection versus IAN block plus
labial infiltration) and solutions (articaine versus lidocaine) differed between our study
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and his. Compared to Clark’s findings of 38-40% success on the central incisor, the
higher success in the central incisor (56%) in our study may primarily have to do with the
localized volume of anesthetic penetrating deeper into the central core of the nerve
bundle (37, 197). Another possible reason for our higher success in the central incisor
could be from the effect of cross innervation anesthesia on the central incisor. Although,
studies have concluded that cross innervation only accounts for about 10% to 27% of
anesthesia (12, 110), this may have helped to increase our success. Our Group 2 success
#1 was significantly lower than our Group 1, such that only the Group 2 central incisor
success (6.1%) came near to what Clark et al. (3) found with a successful IAN block
(10%) and no supplemental lidocaine. Clearly, a single articaine infiltration cannot be
advocated for lower incisors and canines. But, a double infiltration (43-60%) of articaine
(Group 1) is at least similarly efficacious in the mandibular anterior teeth as compared to
a successful IAN block plus a labial infiltration of lidocaine (40-62%) (3). No studies to
date, utilizing a similar continuous success criterion for lower anterior teeth, can be
directly compared to the current study, but the clinical application of both Clark’s and our
definitions of success make these results more relevant to what patients and doctors
expect from anesthesia (i.e. continuously numb for the whole dental appointment).
Nist et al. (6) utilized a similar definition of success for incisive nerve blocks.
Anesthesia was considered successful when an 80 reading was obtained within 15
minutes and sustained for the entire 60 minute test period. Nist et al. (6) found that the
anesthetic success of 1.8 mL of 2% lidocaine with 1:100,000 epinephrine in an incisive
nerve block to be 8% for the lateral incisor and 2% for the central incisor, and the failure
to be 55% and 72% respectively . The incisive nerve block alone did not successfully
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anesthetize the central and lateral incisors. Yet, the combination of the incisive nerve
block plus an IAN block (3.6 mL of 2% lidocaine with 1:100,000 epinephrine)
significantly enhanced pulpal anesthesia in the lateral incisors (from 8% to 60%) and
significantly reduced failures (from 55% to 10%). Our anesthetic success of 7% (Group
2) for labial infiltration is very similar to Nist’s findings of 8% (6). But due to different
solutions and experimental protocol, direct comparisons are not feasible between the
studies.
Pabst (27) and Robertson (25) used similar success definitions when considering
pulpal anesthesia in posterior mandibular teeth. Both authors defined anesthetic success
as achieving the first of two consecutive 80/80 readings within 7 to 8 minutes, and then
sustaining these readings continuously for at least 60-minutes. Pabst (27) found
successful pulpal anesthesia for a repeated infiltration (total of 3.6 mL of articaine) and a
single buccal infiltration of 1.8 mL of articaine with 1:100,000 epinephrine, respectively,
as follows: in 31.4% and 4.7% of the second molars; 43.0% and 10.5% of the first
molars; 57.7% and 23.5% of the second premolars; and 49.4% and 20.5% of the first
premolars. Statistical analysis of anesthetic success found significant differences
between the two groups for all four of the test teeth. Robertson’s (25) results showed that
a single articaine infiltration produced successful pulpal anesthesia in 10.0% of the
second molars; 10.0% of the first molars; 31.7% of the second premolars; and 31.6% of
the first premolars. In Group 2 of our study, successful anesthesia successively decreased
from 9.8% for the canine, to 7.3% for the lateral incisor, and finally to 6.1% for the
central incisor, in spite of the injection site being over the lateral incisor. These results
are similar to those found by Robertson (25) and Pabst (27) for single buccal infiltrations.
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In relation to the anterior and posterior teeth positions, the percentage increase for Pabst’s
repeated injection versus our study’s double injection (Group 2) was 26.7% versus 32.9%
for the posterior tooth (2nd molar versus canine), 32.5% versus 50.0% for the test tooth
(1st molar and lateral incisor), and 34.2% versus 52.5% for the anterior tooth (2nd
premolar and central incisor).
The repeated buccal infiltration injection was significantly more effective than the
single buccal infiltration. This could suggest that location of the second injection matters
less than the volume of anesthetic given. For our study, this could indicate that a double
volume of anesthetic on the buccal or lingual may produce the same significant increase
in anesthesia that was seen between Group 1 and 2. Further research should investigate
this with concern to patient morbidity (labial more painful than lingual) and volume
given at the test site.
Overall, the significant difference between the Group 1 and Group 2 findings
show that the articaine infiltration can not be advocated as a single labial injection. The
labial and lingual application may be utilized clinically, yet the percentages of anesthesia
are not near the desired 60 minutes of continuous pulpal anesthesia that may be required
for some clinical procedures. The reasons for the large difference between the groups
may be related to anatomic differences and the volume of solution deposited.
When compared to our study, more research has utilized the second definition of
success, making simpler the comparisons for the lower anterior teeth. The second
definition, Success #2, was defined as the occurrence of two consecutive 80 readings
with the EPT within the 60 minutes of testing. This definition excluded only subjects
who experienced complete failure. Using the mandibular labial and lingual infiltration
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injections, Group 1 (1.8 mL labial and 1.8 mL lingual to the lateral incisor) and Group 2
(1.8 mL labial to the lateral incisor, followed by a lingual mock infiltration at the lateral
incisor apex) produced successful pulpal anesthesia, respectively, as follows: 97.6% and
75.6% for the lateral incisors (p<0.05); 98.8% and 81.7% for the central incisors
(p<0.05); and 92.7% and 74.4% for the canines (p<0.05). Statistical analysis of
anesthetic success found significantly higher success rates for Group 1 versus Group 2
for all three of the test teeth (Table 9).
Haas et al. (16, 20), in two different infiltration studies using 1.5 mL 4% articaine
with 1:200,000 epinephrine, found that articaine produced successful anesthesia in the
canine region 50% to 65% of the time, while achieving lingual soft tissue anesthesia 10%
of the time. Pulpal anesthesia was assessed by electric pulp tester readings for a period of
25 minutes. Compared to Haas’ canine success, our Group 1 and Group 2 success, being
93% and 74% respectively, were both higher. These success differences between our
study and Haas’ may be related to population differences (age and gender), sample size
differences (82 versus 20) and or volume differences (3.6 mL and 1.8 mL versus 1.5 mL).
Rood (110, 111) showed 100% success for central incisors after adding a labial
infiltration (likened to our Group 2) over the central incisor apex of 1 mL of lignocaine
with 1:80,000 epinephrine to the earlier administered IAN block of 1.5 mL of lignocaine
with 1:80,000 epinephrine. The success difference between our study and Rood’s (82% in
our Group 2 versus 100% in Rood’s) may be related to Rood’s small sample size, the
added efficacy of an IAN block, or the solution difference. In our study, a similar high
success (98% and 99% anesthetic success of the lateral and central incisors, respectively)
was noted for the labial and lingual combination (Group 1). Clark et al. (3) showed a
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success rate of 62% (over the lateral incisor) and 40% (over the central incisor) using 3.6
mL of 2% lidocaine with 1:100,000 epinephrine in an IAN block with an infiltration
(injected over the apex of the lateral incisor) using 1.8 mL of 2% lidocaine with
1:100,000 epinephrine. These studies (3, 110, 111) showed significant improvement of
pulpal anesthesia for mandibular anterior teeth when a labial infiltration was added to the
IAN block. Though similar to our study, direct comparison is impossible due to
experimental protocol and anesthetic solution differences.
Yonchak et al. (21) compared the anesthetic efficacy of labial infiltrations using
either 1.8 mL of 2% lidocaine with 1:100,000 epinephrine or 1.8 mL of 2% lidocaine
with 1:50,000 epinephrine over the lateral incisor apex at two separate appointments in
40 subjects. Additionally, 40 subjects were given a lingual infiltration over the lateral
incisor apex of 1.8 mL of 2% lidocaine with 1:100,000 epinephrine. Anesthesia was
considered successful when two consecutive 80 readings were obtained. The success
rates for the lateral incisor ranged from 43-50% for all three infiltrations. The adjacent
canine had success ranging from 27% (lingual) to 53% (labial with 1:50,000
epinephrine). The central incisor had success ranging from 47% (lingual) to 63% (labial
with 1:100,000 epinephrine). A similar anesthetic distribution was noted in our study,
namely that the central incisor had a similar anesthetic success to the lateral, over which
the anesthetic was deposited in both studies (99% for Group 1 central incisor versus 98%
for Group 1 lateral incisor, 82% for Group 2 central incisor versus 76% for Group 2
lateral incisor). The more notable difference between the lateral and central incisor was
with Group 2 (76% and 82% respectively), and this group is more directly comparable to
Yonchak’s labial infiltration group (noting that he utilized only 1 cartridge of lidocaine,
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and never two, as in our Group 1). Though the results of our study may not be
statistically different, the anesthetic spread seems to favor the more anterior teeth. As
previously discussed, this anterior distribution may favor anatomical differences in bone
and supporting structures (185). But Yonchak et al. (21) found no statistical difference
between the labial and lingual approach using lidocaine, and one could assume that bony
anatomy and attachments of muscles had little effect on the infiltration success in his
study. Overall, articaine has been shown to have greater diffusion through bone because
of its molecular configuration, the lipophilic thiophene ring, and because of the high
partition coefficient of articaine (123.0) compared to lidocaine (10.0) found by Casanova
et al. (84). Thus in our study, a labial infiltration of the same volume of articaine and
epinephrine appears to be more efficacious than the same volume of lidocaine in the
anterior mandible (Group 2 articaine success : 74% to 82%; lidocaine success: 45% to
63%). The greater efficacy of articaine compared to lidocaine in a single cartridge may
be due to “the unique chemical structure of articaine, with its thiophene ring and ester
side chain, which may allow for enhanced osseous penetration of the anesthetic. Its
plasma protein binding is approximately 95% while lidocaine is approximately 65%. The
lipid solubility ratio of articaine to lidocaine is approximately 3 to 8 (54). If the
molecular structure or higher concentration of articaine results in more anesthetic
diffusing through the mandibular cortical plate, and if this tends to occur in a certain
anteroposterior location of the mandible due to differences in cortical plate thickness or
density, we would expect to see a preference for anesthesia to occur in one tooth.”(25)
All solutions demonstrated a steady decline in pulpal anesthesia over 60 minutes.
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In our study, when compared to the lateral incisor, the similarly high success of
the central incisor may have more to do with the volume of articaine anesthetic
overwhelming and penetrating through both cortical plates (as in Group 1) and into the
central core of the incisive nerve, as well as it’s ability to anesthetize any crossover
innervation that could occur from the contralateral incisive nerve (12, 110, 111).
Yonchak et al. (12) found that the central incisor, when bilateral inferior alveolar nerve
blocks were performed (successful lip anesthesia with 3.6 mL 2% lidocaine 1:100,000
epinephrine, bilaterally), was successfully anesthetized (two consecutive 80 readings
within 60 minutes) only 66% of the time, compared to our study in which centrals had
99% anesthetic success with the double injection (Group 1) and 82% with the single
infiltration (Group 2) of articaine. Together, our study and Yonchak’s (12) study show
that although central incisors, and mandibular anterior teeth in general, may be affected
by cross innervation, anterior teeth may be more affected by the anesthetic’s ability to
penetrate in to the central core of the nerve trunk (37, 197). In general, the anterior
infiltrations of articaine, at least in the total volume and locations given in Group 1,
appear to penetrate more successfully than lidocaine.
Meechan and Ledvinka (13) compared a single labial infiltration with a
combination of a labial and lingual infiltration over the apex of central incisors, using 2%
lidocaine with 1:80,000 epinephrine, and found 50% success versus 92% success,
respectively. Meechan and Ledvinka (13) only utilized 0.5 mL of 2% lidocaine with
1:80,000 epinephrine both labial and lingual to the central incisor. The study only
incorporated 12 subjects in a repeated-measure design in which the central incisor was
tested for up to 30 minutes, at 2 minute intervals. Anesthetic success was determined as
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no discomfort at the maximum reading of 80 μA on the electronic pulp tester. The
combination of labial and lingual infiltrations of lidocaine appears to have an increased
success compared to a single infiltration alone. The authors (13) found a similar success
rate for central incisors (92%), similar to the 99% found in our study for Group 1. But
comparing labial lidocaine success (50%) to labial articaine success in Group 2 (82%), a
single infiltration with labial articaine resulted in much greater anesthetic success than
lidocaine. A direct comparison is impossible, but both studies agreed that a combination
of labial and lingual infiltrations is significantly better for anesthetic success in the lower
mandible. Yet due to the added variable of volume difference between Group 1 and
Group 2, the location may not be as significant as the volume. Meechan and Ledvinka’s
study (13) had such a small sample size that success results by injection site location
(labial and lingual) may be misrepresentative of results from a larger population.
Pabst (27) showed that a repeated infiltration of articaine (25 minutes after the
initial infiltration) versus a single buccal infiltration of articaine in posterior teeth
produced successful pulpal anesthesia, respectively: 84.9% and 69.8% for the second
molar; 83.7% and 66.3% for the first molar; 97.7% and 78.8% for the second premolar,
and 92.8% and 80.7% for the first molar. Overall, the anesthetic success of the
combination labial and lingual infiltration (Group 1) followed a similar increase in
success (with increases of 17.1% to 22.0%, compared to Pabst’s increase of 12.1% to
18.9%). In Pabst’s study, the repeated buccal infiltration injection was significantly more
effective than the single buccal infiltration. This could suggest that location of the second
injection matters less than the volume of anesthetic given. For our study, this could
indicate that a double volume of anesthetic on the labial or lingual may produce the same
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significant increase in anesthesia that was seen between Group 1 and 2, and this may
need to be studied further.
Robertson (25) also utilized this definition of success (two consecutive 80/80
readings at any time) when evaluating the efficacy of a single buccal infiltration injection
with articaine. Their results indicated that pulpal anesthesia was achieved in 80.0% of
second molars, 90.0% of first molars, 93.3% of second premolars, and 87.7% of first
premolars. With the exception of the central incisor, Robertson’s percentages are higher
than what was found with our Group 2 (single labial infiltration) but lower than what was
found by our Group 1 (labial and lingual articaine infiltration). This difference may be
related to location of infiltration, population, or operator differences. But in general
Robertson’s findings have also tended to be higher than other posterior studies to date
(18, 22, 87, 88). Direct comparisons are impossible due to location and different volumes
of articaine used in our study.
Kanaa et al. (18) determined anesthetic success in thirty-one healthy adult
volunteers who were pulp-tested at 2-minute intervals following a mandibular buccal
infiltration over the first molar with 1.8 mL 4% articaine with 1:100,000 epinephrine.
Like our study, success was defined as two consecutive 80/80 pulp tester readings at any
time during their testing period (the authors only tested for 30-minutes). They found a
64.5% success rate for first molars (the test tooth). We found 81.7% success over the test
tooth (the lateral incisor) with Group 2 (single labial articaine infiltration only). When
we doubled the volume (Group 1), our success rate was even higher (97.6%). “Another
study by Corbett et al. (88) compared the anesthetic efficacy of a mandibular buccal
infiltration with articaine to a buccal plus lingual infiltration with articaine. Thirty-one
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volunteers with at least one vital first molar tooth were given a buccal infiltration of 1.8
mL 4% articaine with 1:100,000 epinephrine plus a mock lingual injection or a buccal
infiltration of 0.9 mL 4% articaine with 1:100,000 epinephrine plus a lingual infiltration
of 0.9 mL 4% articaine with 1:100,000 epinephrine. Success was defined as an 80/80
reading on the electric pulp tester on two or more consecutive measurements. A single
buccal infiltration injection in their study resulted in a 64.5% success rate and a buccal
plus lingual injection resulted in a 67.7% success rate (88).”(27) Again, 65% to 68% is
less than our 81.7% success rate found in Group 2, using the same volume of anesthetic
(Table 9). Our findings suggest that a single labial infiltration in the anterior is more
efficacious than a single buccal infiltration in the posterior mandible. The primary reason
for the higher success in the anterior may be most related to a thinner labial cortical plate
(158, 185). Another possible reason for the difference could be that both of the posterior
studies had smaller sample sizes (31 subjects) than our study (82 subjects), and having
studied a greater sample size may have elicited a greater response.
“Meechan and Kanaa (22) compared the efficacy of buccal and buccal plus lingual
infiltration injections for permanent mandibular first molars. Thirty-one healthy
volunteers randomly received either a buccal infiltration injection with 1.8 mL 2%
lidocaine with 1:100,000 epinephrine and a mock lingual injection or a buccal and lingual
infiltration injection with 0.9 mL each of 2% lidocaine with 1:100,000 epinephrine.
Success was defined as two consecutive 80/80 readings on the electric pulp tester.”(27)
Success was found in 38.7% of buccal infiltrations and 32.3% of combination injections
(22), both of which were much lower than our Success #2 for both Group 1 and 2
(compared to the tooth tested: 1st molar versus lateral incisor). The lack of difference
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between buccal and lingual infiltrations and a buccal alone may indicate again that
location (labial or lingual) has less of an effect than does volume of anesthetic.
Buccal infiltration anesthesia is an easily mastered technique that can be used for
primary or supplemental injections in the anterior mandible. It requires very little time
and does not mandate specialized equipment. Various authors have investigated the
efficacy of a primary intraosseous injection using 1.8 mL of 2% lidocaine with 1:100,000
epinephrine as an alternative method of improving anesthetic success in the mandibular
first molar. Using the definition of success as achieving two consecutive 80/80 EPT
readings at any time during a 60-minute test period (Success #2), first molar anesthesia
success ranged from 74% to 100% (172, 198-200). Coggins (199) used the Stabident
system as a primary injection in asymptomatic lateral incisors using 2% lidocaine with
1:100,000 epinephrine. He reported an anesthetic success (Success #2) of 78% in
mandibular lateral incisors. Onset was immediate, but the frequency of 80/80 readings for
the lateral incisor and the adjacent teeth did not remain above 75% for more than 10
minutes. In our study, the mandibular labial infiltration using 1.8 mL 4% articaine with
1:100,000 epinephrine (Group 2) had an nearly equivalent success rate of 76% under this
definition of success, with the frequency of success for all teeth being similar, although a
slower decline in anesthesia was noted. However, when a lingual infiltration using 4%
articaine with 1:100,000 epinephrine is given immediately following a labial infiltration
of the same solution (Group 1), the success rate for the lateral incisor is increased to 98%
(Table 9), and the frequency of 80/80 readings remained over 75% for at least 33 minutes
(minute 7 to 40) (Table 6). When compared to supplemental intraosseous injection
success (98%) after IAN block in posterior teeth with irreversible pulpitis (201), our
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Group 1 success is very similar. But when compared to asymptomatic teeth with
supplemental intraosseous injection of lidocaine after IAN block, intraosseous works
significantly better than even our double infiltration of articaine (95). These studies (95,
201) didn’t determine success for anterior teeth, so direct anterior success differences
cannot be considered. Yet overall, our findings suggest that a labial and lingual
infiltration for mandibular anterior teeth may be similar in anesthetic efficacy to the
primary intraosseous injections of lidocaine or mepivacaine. A direct comparison in a
blinded, repeated-measures study would be needed to test this hypothesis.
Under both definitions of success used in this study, Group 1 consistently showed
higher percentages of success for all three teeth tested when compared to Group 2.
Success #1 accurately describes pulpal anesthesia that occurs within a reasonable amount
of time for dental treatment to start without delay (10 minutes for incisors and 11 minutes
for canines) and that lasts continuously throughout a 60-minute treatment period, ideally
required for most dental procedures. Thus, it is possible to assume that any subject
considered a success under this definition may not experience pain during a 60-minute
dental appointment if treatment is started 10 minutes after the injections (labial and
lingual). Success #2 only ensures a minimum of six consecutive minutes of anesthesia at
any time throughout the 60-minute testing period. This definition is not as clinically
relevant as the previous two definitions, but was included in our study for the purpose of
comparison with other studies using a similar definition of success.
Anesthetic Failure
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In this study, failure to achieve two consecutive 80/80 readings at any time
during the 60-minute testing period was considered an anesthetic failure. Giving a labial
infiltration with articaine (Group 2) resulted in a consistently higher failure rate for each
tooth than the labial and lingual combination infiltration with articaine (Group 2).
Anesthetic failures were reported for Group 1 and Group 2, respectively, as follows:
7.3% and 25.6% for the canines; 2.4% and 24.4% for the lateral incisors; and 1.2% and
18.3% for the central incisors (Table 10). All of these differences in failure rates were
highly statistically significant (p=0.0026 for the canine, p=0.0001 for the lateral incisor,
and p=0.0026 for the central incisor).
Haas et al. (16, 20), in two different infiltration studies using 1.5 mL 4% articaine
with 1:200,000 epinephrine, did not specifically report failure rates. Haas only utilized a
25 minute test period and a single median pulp test reading of 80 to determine anesthetic
success. Assuming our definition of failure, one could compare to Haas’ anesthetic
success (i.e. 65% success, leaving 45% that did not achieve success). Thus, our failure
rate of 7% (Group 1) and 26% (for Group 2) is much lower than his 45%. When
comparing just labial infiltrations with articaine (26% in our study versus 45% in Haas’
study), our smaller failure rate may be due to a slightly higher volume of anesthetic (1.8
mL vs 1.5 mL), a more anterior location of injection (lateral incisor apex versus canine
apex), a doubled concentration of epinephrine, or a greater number of samples (82 versus
20).
Utilizing the same definition of failure as in our study, Nist et al. (6) reported
failure rates for the incisive nerve block, using 2% lidocaine with 1:100,000 epinephrine,
as 72% for the central incisor and 55% for the lateral incisor. Comparing these figures to
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the current study’s failure rates, the labial infiltration of articaine (Group 2) produced
much lower failure rates (18.3% and 24.4%) for both incisors compared with a lidocaine
incisive nerve block. The higher failure of the incisive nerve block is most likely due to
the location of needle insertion/injection during the block being within the mental
foramen, and therefore further from the area of the incisors. Though the experimental
protocol, solutions, and injection sites differed, the IAN block plus the incisive nerve
block produced significantly more failures (30% for central incisors and 10% for lateral
incisors) compared to our Group 1 (1% for central incisors and 2% for lateral incisors).
Yet, the IAN block plus the incisive nerve block produced very similar failure rates
compared to our Group 2 (18% for central incisors and 24% for lateral incisors). When
compared to an incisive nerve block or an incisive nerve block with an IAN block, the
labial and lingual infiltration of articaine produced less failures in the anterior mandible.
Using the same definition, Clark et al. (3) reported a failure rate, using lidocaine
for the labial infiltration after an IAN block, as follows: 10% for the canine, 12% for the
lateral incisor, and 15% for the central incisor. The failure rates of our study were higher
for each tooth, as follows: the canine was 25.6% (16% higher); the lateral incisor was
24.4% (12% higher); and the central incisor was 18.3% (6% higher). Again this
difference may be related to the added success of a mandibular block. Direct comparison
is impossible. With Group 1, our failure rates were all considerably less, as follows: the
canine was 7.3% (3% less); the lateral incisor was 2.4% (10% less); and the central
incisor was 1.2% (14% less). When compared to Clark’s study, one may conclude that a
labial and lingual infiltration using articaine will produce much less failures than a labial
lidocaine infiltration after a successful block, but this does not mean that a combination
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of a labial and lingual infiltration of articaine is more successful over an hour
appointment.
Yonchak et al. (21), comparing the anesthetic efficacy of labial infiltrations using
either 1.8 mL of 2% lidocaine with 1:100,000 epinephrine or 1.8 mL of 2% lidocaine
with 1:50,000 epinephrine over the lateral incisor, found labial anesthetic failure rates as
follows: 47-53% for the canine, 55-57% for the lateral incisor, and 37-40% for the central
incisor. When compared with a labial infiltration of articaine only, our failure rates were
significantly less. When compared to Yonchak’s findings (21), the central incisor failure
rate of 18.3% was 19-22% lower, the lateral incisor failure rate of 24.4% was 31-33%
lower, and the canine failure rate of 25.6% was 21-27% lower than Yonchak’s. One
could conclude that a labial infiltration using articaine will produce much less failures
than a labial lidocaine infiltration. And finally for even greater reliability, a labial and
lingual articaine infiltration may produce less failures (1% to 7%), compared to a labial
lidocaine infiltration.
Meechan and Ledvinka (13) compared a single labial infiltration with a
combination of a labial and lingual infiltration over the apex of central incisors, using 2%
lidocaine with 1:80,000 epinephrine, and found 50% failure versus 8% failure,
respectively. Our single labial infiltration failure rate was 18.3% for the central incisor,
while our labial and lingual failure rate was 1.2%. A direct comparison is impossible, but
both studies agreed that a labial and lingual infiltration produced significantly less
failures. Yet due to the added variable of volume difference between Group 1 and
Group 2 in our study, the location may not be as significant as the volume. Meechan and
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Ledvinka’s study (13) incorporates such a small sample size that resulting success by
location may be misrepresentative of a larger population.
The current study revealed much higher anesthetic failure rates when only a labial
infiltration of articaine was given compared to when a labial and lingual infiltration of
articaine was given immediately. Anesthetic failure reveals the inability to produce six
consistent minutes of anesthesia during a sixty-minute testing cycle. The high incidence
of failure with a single labial infiltration injection with articaine (from 18.3% of central
incisors to 25.6% of canines) would indicate that a high percentage of patients would
have pain (complete lack of anesthesia) during treatment of a mandibular posterior tooth
when this technique is used alone. These patients would require supplemental anesthesia
or a possibly a repeated injection to be comfortable during the procedure. Yet when a
labial and lingual infiltration of articaine is utilized, a very low percentage (1.2% to
7.3%) would have a complete lack of anesthesia.
Onset of Pulpal Anesthesia
Onset times for pulpal anesthesia, in minutes, for each tooth with each solution
can be found in Appendix J. Onset of pulpal anesthesia was defined as the time at which
the first of two consecutive 80/80 readings with the electric pulp tester occurred. The
mean onset times for pulpal anesthesia are summarized in Table 11. Only matched-pairs
could be statistically analyzed, meaning only those subjects who had onset times for each
group per tooth were analyzed. For this reason, the number of subjects analyzed per
tooth group differed from the total number of subjects tested. It should be noted that
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anesthetic failures would not be included in this data because, by definition, there can be
no onset of anesthesia when anesthetic failure occurs.
Statistical analysis of onset times found a statistically significant difference
(p<0.05) between Group 1 and 2 for the central incisor and canine, with Group 1
producing consistently quicker onset than Group 2. There was no significant difference
in onset time between the two groups for lateral incisor (p>0.05). The canine had a
mean onset of 5.0 minutes in Group 1 and 6.3 minutes in Group 2. The lateral incisor
had a mean onset of 4.0 minutes in Group 1 and 4.7 minutes in Group 2. The central
incisor had a mean onset of 3.0 minutes in Group 1 and 3.9 minutes in Group 2. The
standard deviations of Group 1 ranged from 3.6 minutes to 3.9 minutes, while in Group 2
the range was from 3.3 minutes to 4.5 minutes. The Group 1 central incisor showed an
onset time almost 1 minute faster (0.9 minutes) than Group 2, but because the standard
deviations are so large (3.9 minutes and 3.3 minutes), the significance of this is
questionable. The Group 1 canine showed an onset time of more than 1 minute faster
(1.3 minutes) than Group 2, but again because the standard deviations are so large (3.6
minutes and 4.5 minutes), the significance of this is questionable. Yet for all anterior
teeth tested, a faster onset mean was always noted in the labial plus lingual infiltration
(Group 1) when compared to the labial only infiltration (Group 2). Because only
matched pairs could be evaluated, if a subject did not gain onset (i.e. anesthetic failure) in
even one of two appointments, this subject was eliminated from statistical analysis of
onset.
“Between-tooth comparisons were not statistically analyzed since the teeth were
tested at different time intervals throughout the appointment. In order to make a valid set
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of between-tooth comparisons for the onset of pulpal anesthesia, all the teeth would have
had to be pulp tested at the same time to determine the exact time of anesthesia onset.
This would require the use of separate electric pulp testers for each tooth. Unfortunately,
the current design of the electric pulp tester made this impossible.
In addition, because readings were taken every three minutes, onset that occurred
between tests could not be recognized. Therefore, onset times are exact to within two
minutes of actual onset due to the limited test sensitivity. In order to get an exact onset
time, a continuous testing device would be needed.”(27)
The incidence, in the current study, of a statistically significant difference
between anesthetic volumes (Group 1 versus Group 2) for onset times for each tooth type
is interesting, though probably not clinically relevant. These small differences in onset
times for central incisors and canines seem to support the mechanism whereby the
anesthetic solution diffuses through the lingual cortical plate in order to reach the incisive
nerve. Because a lingual infiltration was not done in a separate appointment, injection
site can not be independently evaluated. Though the lingual cortical plate may differ, we
cannot conclude this. The onset speed may be related to the volume of anesthetic
concentrated around the alveolus in the test area, rather than the differences in labial and
lingual cortical plates. Future studies could consist of doubling articaine anesthetic
solutions on the same side of the alveolus, helping to determine these bony differences.
As discussed earlier, this onset time was calculated as the amount of elapsed time
from the completion of the second (lingual or mock lingual) infiltration. Specifically,
these onset times (as reported in Table 11) exclude the time taken for the labial injection
and either the lingual or mock injection (a minimum total of 2 minutes). An additional
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0.5 minute was utilized for removal, reloading, and replacement of the syringe into the
lingual vestibule. The digital timer was immediately started after the completion of the
second injection. Thus, the total elapsed time before the timer was started was
approximately 2.5 minutes, and the pulp-tester was not utilized (on the lateral incisor)
until one minute had passed on the timer. The direct comparison of mean onset times
from this study to other studies (14, 87) would require the addition of approximately 1.5
minutes to our onset times (Table 11) to be valid. This is because each of these studies
only had a single initial injection of 60 seconds prior to the start of their experimental
time, while our study incurred an additional 1.5 minutes due to the lingual injection and
syringe reloading. Thus, experimental comparisons would raise our onset times from 3-5
minutes (Group 1) to 4.5-6.5 minutes, and to 5.4-7.8 minutes for Group 2. Thus, a labial
and lingual infiltration of articaine in the lower mandible results in a clinical onset time
starting one minute later (i.e. 2.5 minutes after start of labial injection versus 1.5 minutes
after) ranging from 5.5 to 7.5 minutes for lower anterior teeth when utilizing a labial and
lingual infiltration injection. Our experimental onset times (5.4-7.8 minutes) for a single
anterior infiltration of articaine were slightly higher than Robertson’s (4.2-4.7 minutes)
and Pabst’s (4.7-6.6 minutes) means for a single posterior infiltration (14, 27). Thus, the
experimental onset time of a labial cartridge of articaine in the anterior would appear to
take approximately 1 minute longer (about 5-8 minutes) than a buccal cartridge of
articaine the posterior (about 4 to 7 minutes). Ultimately, the clinical onset time (1
minute later than experimental onset time) of an anterior labial infiltration would occur
between 6-9 minutes, compared to 5-8 minutes for the posterior infiltration. As discussed
earlier, the slower onset time could be related to anesthetic being deposited into the
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mentalis muscle space (185), slowing diffusion to the incisive nerve. This could
potentially impede anesthetic flow to the cortical plate and cause a more latent onset time
for anterior infiltrations (185). When the combination labial and lingual infiltration was
utilized the experimental mean onset time is relatively the same as that found for the
posterior studies (4.5-6.5 minutes in our study versus 4.2-6.6 minutes in Robertson’s (25)
and Pabst’s (27) studies). We could assume that a labial and lingual infiltration may have
a clinical onset time similar to posterior infiltrations. The similarity in onset times
between the anterior combination infiltration (Group 1) in our study and the single
posterior buccal infiltration is more difficult to directly compare, primarily due to the
volume differences (3.6 mL in our study versus 1.8 mL in the other two studies);
although anterior versus posterior and labial and lingual versus buccal locations also
complicate the comparison.
Slow Onset of Anesthesia, Short Duration of Anesthesia and Noncontinuous
Anesthesia
"Slow onset of anesthesia represents a longer-than-usual amount of time
necessary for the anesthetic to diffuse through tissues into the nerve bundle to affect its
action. This may be the result of depositing the anesthetic solution further from the nerve
so that diffusion through more muscle, fat, connective tissue or bone is necessary.
Thicker cortical bone, or more dense bone, would be expected to slow diffusion of
anesthetic, leading to a slower onset or failure of anesthesia. Slow onset may also be due
to a compromised ability of the anesthetic to diffuse through tissues quickly enough.
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Clinically, slow onset of anesthesia may result in patient discomfort if the dental
procedure is started too soon.”(25)
Under Success #1 and 2, slow onset would have occurred if the incisors had their
first of two consecutive 80/80 readings after minute 10, or if the canines had their first of
two consecutive 80/80 readings after minute 11 and therefore would not be considered
successful. As discussed above with mean onset times, slow onset data could only be
statistically analyzed with matched-pairs, meaning only those subjects who had onset
times for each group per tooth were analyzed. For this reason, the number of subjects
analyzed per tooth group differed from the total number of subjects tested and any
anesthetic failures would not be included in the data.
In our study, slow onset of anesthesia (defined by Success #1 and #2) occurred in
Group 1 and 2, respectively, as follows: 3.5% and 8.8% of the time in canines, 1.7% and
10.0% of the time in lateral incisors, and 1.5% and 3.0% of the time in central incisors
(Table 12). No significant differences were found for any of the three teeth. Data for
slow onset of anesthesia was not analyzed by Robertson (25), Kanaa et al. (18), Corbett et
al. (88), Haas (16, 20), Rood (111, 202), Meechan and Ledvinka (13), Clark et al. (3),
Yonchak et al. (21), or Meechan and Kanaa (22) and therefore, no comparisons could be
made. Pabst et al. (27) found slow onset for a repeated buccal articaine infiltration and
single buccal articaine infiltration as follows: 36.2% and 31.0% of the time in second
molars, 24.6% and 21.1% of the time in first molars, 22.4% and 17.9% of the time in
second premolars, and 30.3% and 27.3% of the time in first premolars. No significant
differences were found for the four teeth she tested. In comparison to Pabst’s study, our
study showed a reduced number of slow onset anesthesia. This difference may primarily
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be due to Pabst’s (27) definition of slow onset only including those subjects reaching the
first of two consecutive 80/80 readings by 7 or 8 minutes, when our study included the
next test period of 10 or 11 minutes. Also this reduction may be due to the anterior
versus the posterior location of the infiltrations in our study, namely that authors have
generally noted a thinner anterior cortical plate labial to the incisors compared to the
posterior buccal plate (158, 185).
“Anesthesia of short duration is defined as achieving two consecutive 80/80
readings initially, losing the 80/80 reading before the end of the 60-minute test period,
and not regaining it for the remainder of the testing period. Like onset, only
matched-pairs could be statistically analyzed for duration. Therefore, anesthetic failures
would not be included in this data because, by definition, there is no duration when
anesthetic failure occurs.”(27) For this reason, the number of subjects analyzed per tooth
group differed from the total number of subjects tested.
The percentage of short duration anesthesia was statistically higher (p<0.0001) in
Group 2 for all teeth, as seen in Table 12. The number of patients with short duration in
Group 1 was 21, 19, and 26 versus 42, 47, and 57 for Group 2, with respect to the canine,
lateral incisor, and central incisor. Significantly more patients in Group 2 had short
duration anesthesia for all teeth (p<0.0001). In our study, the percentage of short
duration was reported in Group 1 and Group 2, respectively, as follows: 41.1% and
82.4% in the canine, 34.6% and 85.4% for the lateral incisor, and 41.3% and 90.5% for
the central incisor. A labial and lingual infiltration (Group 1) decreased short duration by
approximately 41.3% in the canine, 50.8% in the lateral incisor, and 49.2% in the central
incisor. In general, doubling the articaine solution around the test area, reduced short
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duration. Data for short duration of anesthesia was not analyzed by Haas (16, 20), Rood
(111, 202), Meechan and Ledvinka (13), Clark et al. (3), Yonchak et al. (21), or Meechan
and Kanaa (22) and therefore, no comparisons could be made. Although not directly
comparable, Pabst (27) found the percentage of short duration for a repeated buccal
articaine infiltration and single buccal articaine infiltration to follow a similar pattern,
respectively, as follows: 16.1% and 80.4% of the time in second molars, 14.0% and
77.2% of the time in first molars, 6.0% and 53.7% of the time in second premolars, and
1.5% and 66.7% of the time in first premolars. Her differences were also significant
between the two groups for all four teeth (p<0.0001), with the repeated buccal articaine
infiltration having considerably fewer incidences of short duration anesthesia (27). The
increase in articaine volume (from 1.8 mL to 3.6 mL) shows a significant decrease in the
percentages of slow onset in both the posterior and anterior regions. This may indicate
that the location of injection (i.e. buccal or labial versus lingual) matters less than the
volume of articaine solution at that test site. In other words, our results may have been
similar having given a total volume of 3.6 mL of articaine solution labial or lingual to the
lateral incisor. Further research could help to explore these speculations.
“Anesthesia of short duration would result, clinically, in the patient experiencing
pain before the end of procedures requiring profound pulpal anesthesia for a full hour.
Like slow onset of anesthesia, anesthesia of short duration may require the reinjection of
the patient with more anesthetic, but with short duration anesthesia it would be more
likely that the clinician may not believe that the patient is experiencing discomfort, or
may rush the procedure in order to finish more quickly than usual. Depending on the
level of discomfort being experienced by the patient, some clinicians would accept that
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the patient was not going to be completely comfortable and proceed as usual.”(27) Since
Success #1 of our study excluded patients experiencing short duration of anesthesia, it
can be concluded that this scenario would be avoided when anesthesia is considered
successful by this definition. However, Success #2 is not as specific, and subjects who
responded successfully under this definition could still undergo the discomfort of short
duration anesthesia. As shown in our study for anterior teeth and others for posterior
teeth (18, 22, 25, 27, 88), a single labial or buccal infiltration injection of articaine does
not provide a duration long enough to consistently last for an hour long dental
appointment. Yet, the data for anesthesia of short duration in our study suggests that
adding a secondary lingual injection of articaine immediately after the initial labial
injection significantly decreases short duration in the anterior mandible.
Noncontinuous anesthesia is defined as achieving an 80/80 reading initially,
losing the 80/80 reading, and then regaining an 80/80 reading during the testing period.
Success #1 excluded subjects experiencing noncontinuous anesthesia. “Clinically
patients with this phenomenon would experience pain at some point throughout a dental
procedure and could lead to fear and loss of confidence in the clinician. Furthermore, the
clinician would be forced to decide whether or not the anesthesia would return, and
waiting for the return of pulpal numbness would create a delay in treatment.”(27)
In our study, noncontinuous anesthesia was experienced in Group 1 and Group 2,
respectively: 3.5% and 5.3% for the canine, 3.3% and 3.3% for the lateral incisor, and
1.5% and 9.1% for the central incisor. Overall, non-continuous anesthesia represented a
very small sample (5 out of 183 for Group 1, and 11 out of 183 for Group 2). Also, slow-
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onset represented a very small number of patients (4 out of 183 for Group 1, and 13 out
of 183 for Group 2).
Although not directly comparable, Pabst (27) found the percentage of
noncontinuous anesthesia for a repeated buccal infiltration and single buccal infiltration
of articaine to follow a similar pattern, respectively, as follows: 24.4% and 16.3% of
second molars, 19.8% and 11.6% of first molars, 16.5% and 15.3% of second premolars,
and 15.7% and 9.6% of first premolars. She also found no significant difference in the
incidence of noncontinuous anesthesia between the two groups for any of the four test
teeth (27). Generally, our study showed that both a single (3-9%) and the combination
labial and lingual infiltration (1.5-3.5%) of articaine produced less instances of
noncontinuous anesthesia than Pabst’s (27) findings (10-24%). Our lower frequency of
noncontinuous anesthesia could be resulting from the immediate second volume of
anesthetic given in our study versus the 25 minute delay of the repeated injection in
Pabst’ study (27). The delay potentially may have allowed some subjects to lose
anesthesia prior to receiving a second infiltration, categorizing those subjects as
noncontinuous. But this would not explain why a single buccal injection compared to a
single labial infiltration was not equivalent. This may be related to anatomical
differences in the posterior, such as cortical plate thickness, and articaine’s ability to
continually feed through that plate. Yet without data for noncontinuous anesthesia from
Haas (16, 20), Rood (111, 202), Meechan and Ledvinka (13), Clark et al. (3), Yonchak et
al. (21), or Meechan and Kanaa (22), no comparisons to other anterior and posterior
studies can be made. By the strictest definition (Success #1), if a tooth was neither a
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success nor a failure, it could fall into at least one, and possibly all three, of these
categories (i.e. slow onset, short duration, and noncontinuous anesthesia).
DURATION OF PULPAL ANESTHESIA
Duration times for anesthesia were not reported in this study. Duration of pulpal
anesthesia is defined as the time at which the last of two consecutive 80/80 readings by
the electric pulp tester occurred. When deciding whether to include analysis of duration
of pulpal anesthesia in the current study, the fact that pulp testing lasted only an hour was
considered. If testing had been carried out for a couple hours, true duration times could
have been reported. However, because anesthesia had not always fully worn off by the
end of the testing period, duration times could not be accurately analyzed. For the same
reason, other authors have been unable to report true duration times (18, 22, 25, 88).
Also, it must be noted that if the subject never achieved two consecutive 80/80 readings
on a particular tooth (anesthetic failure), the data for that tooth could not be used to
evaluate duration.
Most dental procedures can be completed in an hour or less. Therefore, having a
duration of pulpal anesthesia approaching or exceeding an hour is considered to be
clinically acceptable. The aforementioned success rates (Success #1, in Table 9) give an
indication of a clinically acceptable duration in that, by the definition given for success,
all of these teeth had pulpal anesthesia at the end of the 60-minute time period. True
duration can not be determined because it is not known how much longer past the 60
minute time period these teeth sustained pulpal anesthesia. However, looking at Figures
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1 through 3 may give an indication as to the trend of anesthesia for each tooth and may
allow a clinician to predict the potential duration of pulpal anesthesia.
Previous studies by Robertson et al. (14) and Pabst et al. (87) demonstrated a
decline of pulpal anesthesia over 60 minutes following a single mandibular buccal
infiltration injection. Robertson et al. (14) and Pabst et al. (87) demonstrated a frequency
of 80/80 readings for the first molar (i.e. the test tooth, over which the anesthetic was
deposited), respectively, as follows: 63.3% and 39.5% at 30 minutes, 36.7% and 20.9%
after 45 minutes, and only 18.3% and 15.1% at 60 minutes. Though Pabst reported had
higher results with the double injection, her repeated infiltration took place 25 minutes
after the initial and does not allow a direct comparison to our labial and lingual
infiltration frequencies within the 60 minute test period. The frequency of 80/80 readings
for the lateral incisor (i.e. the test tooth) with a labial and lingual infiltration versus a
labial infiltration only (Table 6) respectively, was as follows: 92.7% versus 48.8% at 31
minutes, 74.4% versus 19.5% at 46 minutes, and 61.0% versus 7.3% at 58 minutes.
Therefore, using only a labial infiltration, the percentage of 80/80 readings (49%, 19.5%,
and 7.3%) followed a similar pattern (compared with Robertson and Pabst) up to 45
minutes before a more significant decline was noted with our study for the final 15
minutes (Figure 1). This apparent difference may be related to faster penetration through
a less dense labial cortical plate, as was suggested by several authors (83, 85, 158, 185).
This could result in faster metabolism of the drug in the cancellous bone with exposure to
higher levels of plasmaesterases, leading to a quicker decline of anesthetic duration. Yet
when a labial and lingual infiltration were given, the percentage of 80/80 readings (93%,
74%, and 61%) in our study was significantly higher, at all time periods, than Robertson
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(14) and Pabst (87). Although true duration was not determined in our study, this longer
frequency of anesthesia with the combination labial and lingual infiltration, with higher
percentages of 80/80 readings at later time periods (i.e. 31, 46, and 58 minutes), appears
to prolong and extend the anesthetic effect of articaine. This prolonged effect may be due
to augmentation of the anesthetic’s effect. Yet, neither in our study nor in the
aforementioned posterior studies did articaine infiltrations result in a 100% “duration” for
60 minutes, as would be clinically desirable.
“Intraosseous injections have also shown a rapid decline in anesthetic duration
over 60 minutes (172, 198, 199). Jenson et al. (172) investigated the effect of a repeated
intraosseous injection given 30 minutes after the initial intraosseous injection using 2%
lidocaine with 1:100,000 epinephrine in the posterior mandible in order to extend this
duration. Success was defined as achieving two consecutive 80/80 electric pulp tester
readings within 5 minutes of injection and sustaining these readings for the entire 60
minutes. Using this definition, only 14.5% of mandibular first molars were found to be
successful using a single intraosseous injection. However, the addition of a repeated
injection increased the success rate to 69.1%.”(27) This finding is similar to our
anesthetic success (59.8%) for the immediate labial and lingual infiltration of articaine
(Table 9, Success #1). The studies differ in design significantly, and had a labial
infiltration had been repeated at a later time, our success may have been higher.
“A drug’s enhanced effectiveness when given repeatedly is referred to as
augmentation (203). Tachyphylaxis is a drug's declining effectiveness when it is given
repeatedly (203).”(172) Our figures (1-3) show relatively high levels of pulpal anesthesia
from minute 4 through minute 40 for Group 1. Pabst et al. (87) found that a repeated
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infiltration did not produce the same effect as the initial injection of articaine (i.e. 25-30
minutes of duration). Instead she found that the duration had been extended past what it
was for the initial injection, demonstrating the drug’s augmentation (87). This
augmentation could be what was also demonstrated our study (Group 1 significantly
more “duration” than Group 2). “A prime consideration that determines whether
augmentation or tachyphylaxis occurs is timing (203). A drug's declining effectiveness,
when given repeatedly, may be observed when a continuous nerve block is used over a
long period of time. This is known as tachyphylaxis (203). Two possible explanations
for this to occur in local anesthetics include a decrease in drug effectiveness or a decrease
in drug concentration at the site of action (203). If a blocking agent is reinjected soon
after the initial signs of returning sensation, tachyphylaxis is less likely to occur. In fact,
augmentation is more likely to occur under these conditions. When the block is allowed
to lapse, tachyphylaxis frequently occurs (203).”(172) In our study, the immediate
lingual infiltration after the labial articaine infiltration ensured no loss of concentration of
anesthetic or sensory return, both of which helped to bolster augmentation of anesthetic
success and duration in the anterior mandible.
POSTOPERATIVE PAIN
Postoperatively, subjects were asked to report injection site discomfort for days 0,
1, 2, and 3 for both groups. Mean pain ratings for Groups 1 and 2 by gender and for
postoperative day are shown in Table 13. Frequency of pain categories for each day and
the distribution between groups, gender, and injection site (labial and lingual) are shown
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in Table 14-17. The same visual analog scale that was used to record pain experienced
during the injection phases was also used for the postoperative pain ratings occurring
with the injection site (Appendix H). Pain ratings were recorded for both injection sites
(labial and lingual) following cessation of anesthesia (Day 0) and in the morning of
postoperative days 1, 2 and 3 after waking from sleep.
Following cessation of anesthesia (postoperative day 0), Group 1 and Group 2
resulted in a mean pain rating of 45.5 mm and 24.8 mm, respectively. Group 2 reported
statistically less (p<0.0001) pain after anesthetic cessation. Though statistically different,
both means fell in “mild category” of postoperative pain. Group 1 males averaged 39.7
mm, while females reported higher pain levels at 51.3 mm (Table 13). The difference
between genders was not significant, though females had a higher overall average. The
means did not fall into the “moderate” category for Group 1, but with the large standard
deviations (30.1 mm and 35.1 mm) it is apparent that moderate pain was experienced by
some after the anesthesia wore off. Group 2 males averaged 23.0 mm, while females
averaged 26.7 mm (Table 13). Again no significant difference between genders was
found. Yet, both male and female Group 2 pain-ratings were significantly lower than
Group 1 (p<0.0001). Seventy-one percent of pain ratings were in the none-to-mild
category, and 27% were in the moderate category, and 3 out of 161 (1.9%) possible
reports noted severe lingual pain after cessation of anesthesia (no severe labial pain was
noted) (Table 14). In Group 2, ninety-one percent of pain ratings were in the none-tomild category, and 8% were in the moderate category, and 0.6% were in the severe
category (a labial pain report) (Table 14).
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For postoperative day 1, Group 1 and Group 2 resulted in a mean pain rating of
28.5 mm and 15.3 mm, respectively. Both means fell in “mild category” of postoperative
pain. Group 1 males averaged 25.6 mm, while females reported slightly higher pain
levels at 31.5 mm (Table 13). The difference between genders was not significant,
though females had a higher overall average. Group 2 males averaged 12.0 mm, while
females averaged 18.5 mm (Table 13). Again no significant difference (p>0.05) between
genders was found. Yet, both male and female Group 2 pain-ratings were significantly
lower than Group 1 (p<0.05). Eighty-seven percent of pain ratings were in the none-tomild category, and 12.3% were in the moderate category, and 1 out of 162 (0.6%)
possible reports noted severe lingual pain (no severe labial pain was noted) (Table 15).
In Group 2, ninety-three percent of pain ratings were in the none-to-mild category, and
7.3% were in the moderate category, and 0% were in the severe category (Table 15).
For postoperative day 2, Group 1 and Group 2 resulted in a mean pain rating of
17.8 mm and 10.7 mm, respectively. Both means fell in “mild category” of postoperative
pain. Group 1 males averaged 16.2 mm, while females reported 19.4 mm (Table 13).
The difference between genders was not significant, though females had a higher overall
average. Group 2 males averaged 8.2 mm, while females averaged 13.3 mm (Table 13).
No significant differences between genders or groups (p>0.05) were found. For Group 1,
ninety-seven percent of pain ratings were in the none-to-mild category, and 3.1% were in
the moderate category, and none reported severe pain (Table 16). In Group 2, ninety-five
percent of pain ratings were in the none-to-mild category, and 5.5% were in the moderate
category, and 0% were in the severe category (Table 16).
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For postoperative day 3, Group 1 and Group 2 resulted in a mean pain rating of
9.2 mm and 7.1 mm, respectively. Both means fell in “mild category” of postoperative
pain. Group 1 males averaged 7.5 mm, while females reported 10.0 mm (Table 13). The
difference between genders was not significant, though females had a higher overall
average. Group 2 males averaged 6.9 mm, while females averaged 7.5 mm (Table 13).
No significant differences between genders or groups (p>0.05) were found. For Group 1,
ninety-nine percent of pain ratings were in the none-to-mild category, and 0.6% were in
the moderate category, and none reported severe pain (Table 17). In Group 2, ninetyeight percent of pain ratings were in the none-to-mild category, and 2.4% were in the
moderate category, and 0% were in the severe category (Table 17).
Robertson (25) and Pabst (27) demonstrated comparable post-operative results for
articaine (when comparing single buccal infiltrations only). Following a buccal
infiltration with 1.8 mL 4% articaine with 1:100,000 epinephrine, Robertson (25) and
Pabst (27) found the mean pain ratings for Day 0, Day 1, Day 2, and Day 3, respectively,
were: 20.2 mm and 27.7 mm, 15.1 mm and 19.3 mm, 11.3 mm and 14.0 mm, and 5.5 mm
and 7.9 mm. All means were in the “mild” category. Our single labial infiltration
resulted in similar findings for Day 0, Day 1, Day 2, and Day 3, respectively, as shown:
24.8 mm, 15.3 mm, 10.7 mm, and 7.1 mm. All means were in the mild category as well.
In a study by Berlin (156), the periodontal ligament (PDL) injection resulted in a
mean pain rating of 35.0 mm for postoperative day 1, 14.7 mm for day 2, and 5.5 mm for
day 3 when articaine was used. Berlin’s postoperative day 1 rating was higher than the
ratings in our study for both groups on day 1. The PDL injection produced a similar
mean rating to Group 2 (10.7 mm and 7.1 mm) on postoperative days 2 and 3, and only
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slightly lower mean ratings compared to Group 1 (17.8 mm and 9.2 mm) on the same
days. Comparing these mean ratings would indicate that the PDL injection may have a
longer duration (into postoperative day 1) of more significant pain initially, compared to
anterior infiltrations; but by day 2 and following, similar mild pain is experienced by both
PDL injections and anterior infiltrations.
In the study by Jensen et al. (172), the intraosseous injection resulted in a mean
pain rating of 31.8 mm after subjective anesthesia ceased, 30.6 mm for day 1, 25.0 mm
for day 2, and 20.8 mm for day 3. This was found to be more painful, in comparison to
the infiltration injection in our study, for all four time periods of Group 2 and for
postoperative day 1 through 3 of Group 1. However, pain ratings for Group 1 were
higher than the intraosseous injection for postoperative day 0. Similar to our study, the
Heft-Parker VAS was used to rate pain. Comparing these ratings would indicate that
using a labial plus lingual infiltration injection may result in higher initial pain ratings,
followed by faster resolution of pain postoperatively than an intraosseous injection.
In the current study, all mean values for both group for all four time periods were
in the “mild” pain range. Pain values decreased for each solution over the three
postoperative days. This is consistent with the results previously described by Robertson
et al. (14) and Pabst et al. (87) who also reported averages in the “mild” pain range that
decreased over the three postoperative days following a mandibular buccal infiltration.
In general, females had a higher overall mean pain rating, but the difference was not
significant. Gender differences in pain ratings have been shown in previous studies (176183), and the occurrence of higher pain ratings by females in our study is consistent with
these findings, though no statistical significance was found. The mean pain ratings
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associated with Group 1 were higher than the mean pain ratings of Group 2 for all for
time periods, but this difference was only statistically significant during Days 0 and 1.
This was also found by Pabst, when utilizing a repeated buccal articaine infiltration
injection (infiltrating with the same volume of articaine as in our Group 1). Pabst (27)
found that a single infiltration resulted in mean pain ratings per postoperative day as
follows: 27.7 mm on day 0, 19.3 mm on day 1, 14.0 mm on day 2, and 7.9 mm on day 3.
Our single labial infiltration resulted in similar findings for Day 0, Day 1, Day 2, and Day
3, respectively, as shown: 24.8 mm, 15.3 mm, 10.7 mm, and 7.1 mm. When giving the
repeated buccal infiltration of articaine, Pabst (27) also found higher mean postoperative
pain ratings as follows: 40.1 mm on day 0, 33.4 mm on day 1, 23.1 mm on day 2, and
13.9 mm on day 3. When comparing to our combination labial and lingual infiltration for
postoperative days, respectively (45.5 mm, 28.5 mm, 17.8 mm, and 9.2 mm), there seems
to be little difference in subjects postoperative pain between injuring the same location
twice (as in Pabst repeated buccal infiltration) and injuring two different locations (as in
our combination labial and lingual infiltration). Although one could have assumed that
trauma to two locations would lead to more postoperative pain clinically than repeated
trauma an already anesthetized tissue, these comparative results don’t appear to
substantiate this. Overall, both Pabst’s study and our study concur that a double
injection, whether repeated or in combination, will initially increase postoperative pain,
immediately after anesthesia wears off (day 0) and the morning after the treatment (day
1).
Postoperative Complications
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Postoperative complications for Group 1 and Group 2 were reported in Tables 181 and 18-2 by postoperative day. Tables 18-1 and 18-2 describe the frequency of
postoperative complications by day for both Group 1 and 2 and location (labial or
lingual). Table 19 is an overall summary of postoperative complications associated with
groups by location (i.e. injection site). Generally, complications diminished from day 0
through day 3. Soreness to touch (i.e. injection site pain) was the most frequently
reported complication for Groups 1 and 2, at 31% and 23% respectively (Table 19). In
Group 1 and Group 2, patients reported swelling 12.3% and 9.8%, pain on opening 3.7%
and 0.6%, bruising 4.9% and 9.8%, chewing pain 1.9% and 0.6%, headache 0.6% and
0%, and nausea 1.2% and 0% of the time. With respect to the repeated articaine
infiltration and the single articaine infiltration, Pabst et al. (27) reported 22% and 22% for
soreness to touch, 16% and 9% for swelling, 3.5% and 3.5% for pain on opening, 3.5%
and 1.2% for bruising, 1.2% and 1.2% for chewing pain, 1.2% and 0% for headache, and
1.2% and 0% for nausea. Some of the categories chosen may seem odd for labial and
lingual infiltrations (e.g. headache and nausea). Thus, the only reason that all of these
complication categories were chosen for the current study was to have direct comparisons
to Pabst study, in which she collected information for all of these categories. Overall,
pain symptoms were similar between the two studies. Slightly higher amounts of
injection site pain and bruising were noted in our study, with the majority of those being
related to the labial aspect. Pain on opening, soreness to chewing, and nausea were
associated with both locations and groups, with a relatively low frequency of occurrence
(0-4%). Out of a possible 326 responses, there were only three (< 2%) reports of pain on
chewing, 1 (< 1%) report of headache, and 2 (1 %) reports of nausea. Both groups
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reported a higher frequency of postoperative soreness to touch and swelling at the labial
injection site, when compared to the lingual site. For the most commonly reported
complications (sore to touch, swelling and bruising), the labial injection produced nearly
twice the number of pain symptoms (65%), when compared to the lingual (35%). This
finding was not anticipated. In general, our expectation was that the lingual may cause
more complications. As discussed by Arens et al. (185), the anatomical differences
between the labial and lingual injection site (i.e. the more superior mentalis muscle
attachment compared with the more inferior lingual muscle attachments) may lend to
greater labial postoperative pain (i.e. mentalis muscle soreness). But in the relatively few
instances (Table 19) of the lingual site producing higher numbers of complications when
compared to the labial (pain on opening, soreness to chewing, and headache), patients
may have had more superior lingual muscle attachments, possibly leading to more painful
tongue movements.
Alternatively, patients may also tolerate fewer complications related to the labial
aspect of their mouth when compared to the lingual. They may be more apt to visually
investigate the injection site, because of the obvious esthetic area of the face. Also, they
may in fact palpate more readily the labial site to check for soreness, bruising and/or
swelling. The lingual site may be more visually obscure, and less likely to affect patient
esthetics, leading to less self observation and complication reports.
“Generally, the postoperative complaints reported by our subjects were likely due
to trauma from the injection. Some people are more likely to note discomfort from this
trauma than others. When muscle tissue is penetrated by the needle during the injection,
it often results in localized tissue damage, which heals within a few days (158).”(27)
179
Trauma may also be caused when the anesthetic is deposited in the dental tissues, causing
them to stretch and expand. Since Group 1 received two cartridges of anesthetic in two
injection sites, multiple tissues would have suffered the damage from expansion caused
by the bolus of anesthetic. This most likely explains why Group 1 experienced more
post-operative pain than Group 2, who only received a single labial cartridge of
anesthetic, but both groups received a second needle insertion.
Malamed et al. (64) reported adverse postprocedural events in 22% of patients
receiving articaine. Nerve blocks and infiltration injections were both included in their
study. The most common complaint of patients receiving articaine was pain, reported by
13%, followed by headache, reported by 4%. The author categorized some adverse events
to be drug-related. The most commonly reported drug-related adverse events were
paresthesia (0.9%), hypesthesia (0.7%), headache (0.55%), infection (0.45%), rash
(0.3%), and pain (0.3%). Of these events, the current study cannot be directly compared
because there is an added variable of a secondary injection site. But, the fact that 31% in
Group 1 and 23% in Group 2 (Table 19) reported soreness at the site of the injections,
shows a higher pain incidence than reported by Malamed (64). This may be due to
differences in experimental protocol, populations sampled, and operators.
In general, complications decreased consecutively from day 0 to day 3. Only
injection site pain (sore to touch), swelling, and bruising, continued to be present (highest
number of reports was 8 on day 3) for the entire survey (Table 18-1 and 18-2). No
patients were evaluated after testing to determine if any of the subject-reported
complications (like “swelling”) were clinically observable and/or diagnosable.
Therefore, some of the self-reported swellings may not have been truly swollen. All
180
other categories diminished relatively quickly and no complications were reported by day
3 (Table 18-1 and 18-2). In general, these trends were reported by Robertson (25) and
Pabst (27).
No incidents of paresthesia were reported by any of the subjects in our study.
However, the number of subjects (82) and number of injections given with articaine (246)
in our study are very low compared to the retrospective studies looking at concerns with
paresthesias and the IAN block (76, 81). It was not possible to determine from our study
whether articaine carried a greater risk than other anesthetics for a mandibular labial or
lingual infiltration. It is extremely unlikely that the technique results in a mental nerve
block, and the observed risk for paresthesia with articaine is usually associated with nerve
block injections. Therefore, the possibility that the injection technique used in our study
may have a higher risk for paresthesia when using articaine compared to lidocaine is
unfounded. Kanaa et al. (18), Corbett et al. (88), Haase et al. (19), Robertson (25), and
Pabst (27) did not report any incidences of paresthesias using articaine solution with a
buccal infiltration. As the overall risk for paresthesia appears to be very low, the benefit
of increased anesthetic success may outweigh the possible risk.
In the current study, postoperative complications were reported by some subjects
in each group (Tables 18-1, 18-2, and 19). With the exception of soreness at the injection
site – “sore to touch” (30.9% in Group 1 and 23.2 in Group 2), “bruising” (4.9% with
Group 1 and 9.8% with Group 2) and “swelling” (12.3% for Group 1 and 9.8% for Group
2), all other post-operative complications occurred less than 4% of the time. None of
this data was statistically analyzed due to the low number of subjects reporting
complications. Neither trismus nor paresthesia was noted by any subjects.
181
Generally, the postoperative complaints reported by our subjects were likely due
to trauma from the injection(s). When muscle tissue is penetrated by the needle during
the injection, it often results in localized tissue damage, which heals within a few days
(158, 185). Some individuals may be more sensitive to this tissue damage and report
discomfort, while others do not report it (158). The postoperative complications between
the two groups were similar, although Group 1 reported slightly more soreness to touch
and swelling than Group 2 (Table 19).
182
CHAPTER 6
SUMMARY AND CONCLUSIONS
The purpose of this prospective, randomized, single-blinded study was to
determine the anesthetic efficacy of a combination labial plus lingual infiltration
compared to a single labial infiltration using 4% articaine with 1:100,000 epinephrine in
mandibular anterior teeth.
Eighty-two healthy male and female volunteers with vital, asymptomatic
mandibular teeth participated in this study. A topical anesthetic agent (20% benzocaine
gel) was placed for one minute at the sites of injection. The primary infiltration for both
groups was administered using 1.8 mL of articaine labial to the lateral incisor at the
approximate location of the lateral incisor root. Immediately following the labial
injection, either a lingual injection was administered using 1.8 mL of articaine lingual to
the apex of the lateral incisor (Group 1) or a mock injection was administered (Group 2).
The mandibular lateral and central incisors and canine were evaluated for pulpal
anesthesia using an electric pulp tester. Subjects rated pain during the injection stages
and postoperatively using a 170 mm visual analog scale.
There was no statistically significant difference in pain intensity between Group 1
and Group 2 for insertion, placement, and lingual deposition. For both groups and all
183
stages of injection, a mild pain rating was found, with the exception of labial deposition
which resulted in an average moderate pain rating. Mean pain ratings for needle insertion
were less than mean pain ratings for both needle placement and solution deposition.
Females reported higher pain ratings than males for all phases of injection in both groups,
but the differences were not significant.
Two definitions of success were used to evaluate pulpal anesthesia. Success #1
was defined as achieving the first of two consecutive 80/80 readings within 10 to 11
minutes and then sustaining these readings continuously for the 60-minute test period.
Success #2 was defined as the occurrence of two consecutive 80/80 readings at any time
during the initial 60-minute testing period. Group 1 had statistically higher percentages
of anesthetic success for both definitions. The groups also produced a statistically
significant difference for anesthetic failure (no consecutive 80/80 EPT readings obtained)
for each test tooth. A single labial infiltration with articaine (Group 2) was associated
with a higher rate of anesthetic failure than an initial labial and lingual infiltration with
articaine (Group 1) for each test tooth.
Statistical analysis of pulpal anesthesia found that Group 1 onset times, for the
central incisor and canine were significantly faster than those in Group 2, while no
statistical difference was found for the lateral incisor. Due to the large standard
deviations that included the means, this statistical difference is not meaningful. Actual
clinical onset time would include an additional 2 to 2.5 minutes from the start of the
initial injection because of time allotted for a labial and lingual injection (1 minute each),
plus removal and reloading of the syringe. This results in a clinical onset time ranging
184
from 5 to 7.5 minutes for lower anterior teeth when utilizing a labial and lingual
infiltration injection.
Slow onset of anesthesia, anesthesia of short duration, and noncontinuous
anesthesia were also compared for the two groups. There were no significant differences
in the incidence of slow onset anesthesia (longer than the 10 or 11 minutes of time for
successful pulpal anesthesia to ensue) or noncontinuous anesthesia (going in and out of
anesthesia) between Groups 1 and 2. However, Group 1 proved to have significantly less
subjects with short duration of anesthesia (duration less than 60 minutes). Therefore,
adding a lingual infiltration of articaine to a labial infiltration appears to significantly
improve the chances that anesthesia will last throughout an entire 60-minute dental
appointment. Our data shows that subjects in Group 1 will experience a longer duration
of pulpal anesthesia than those in Group 2, but the percent of anesthesia decreases over
time in both groups.
Mean postoperative pain ratings revealed a statistically significant difference
between Group 1 and 2 at the cessation of anesthesia (day 0) and on postoperative day 1,
with Group 1 having higher pain levels on these days. There were no statistically
significant differences between groups on postoperative days 2 or 3. Mean postoperative
pain ratings continuously decreased from day 0 through day 3. Like the pain of injection
ratings, females showed higher mean pain ratings for all postoperative days, but this was
not statistically significant. For all postoperative days surveyed, mean pain ratings were
in the “mild” category; therefore, these differences may not be clinically significant.
There did not seem to be a clinically significant difference between the two
groups with regard to the prevalence or severity of postoperative complications. Out of
185
162 and 164 postoperative surveys returned, 25 subjects in Group 1 and 19 subjects in
Group 2 reported tenderness on palpation at the injection site. This was the most
frequently reported complication. In relation to the injection sites, 10 subjects in Group 1
and 8 subjects in Group 2 reported swelling, as well as 4 subjects in Group 1 and 8
subjects in Group 2 reported bruising. Of these more common complications, 65% of the
complaints were related to the labial injection site, while only 35% were related to the
lingual site. Pain on opening, soreness when chewing, headache, and nausea were
reported in much lower frequencies. The complaints decreased in prevalence as the
postoperative days progressed.
The labial and lingual infiltrations of articaine given at the beginning of the
appointment appear to increase anesthetic success, decrease anesthetic failure, and
increase the duration of pulpal anesthesia when compared to a single labial infiltration.
We concluded that the addition of a lingual infiltration injection of 4% articaine with
1:100,000 epinephrine has better efficacy than a single labial infiltration with the same
solution. The combination labial plus lingual infiltration injection of 4% articaine with
1:100,000 epinephrine does provide pulpal anesthesia with a success rate high enough to
support its use as a primary injection technique for mandibular anterior teeth. This
approach may also be useful as an adjunct to other injection techniques, yet future
research will need to examine these possibilities.
186
APPENDIX A
TABLES
187
Males
Females
Totals
# of Subjects
43
39
82
Age Range (years)
19-56
20-55
19-56
Table 1. Biographical data for all subjects.
188
Mean Age (years)
27.1
26.2
26.7
Variable
p-value†
Group 1*
Group 2**
(N=82)
(N=82)
39.8 + 28.3
35.2 + 23.4
44.9 + 32.5
0.6678
0.9940
0.9999
0.9945
p-value†
39.1 + 25.1
37.0 + 24.7
41.5 + 25.7
0.9924
52.5 + 30.6
45.1 + 24.8
60.7 + 34.4
0.2336
0.6452
1.0000
0.7365
p-value†
48.8 + 31.4
45.1 + 27.0
52.8 + 35.5
0.9240
70.4 + 30.9
65.8 + 24.7
75.6 + 36.2
0.8113
0.0643
0.7913
0.4697
p-value†
61.5 + 30.0
58.3 + 28.9
65.1 + 31.2
0.9675
38.2 + 26.0
35.0 + 26.5
41.7 + 25.3
0.9281
0.4724
0.9924
0.9918
p-value†
33.8 + 23.3
31.6 + 23.2
36.4 + 23.4
0.9913
44.1 + 29.3
40.2 + 29.5
48.5 + 28.8
0.8960
0.5686
0.4965
0.2592
p-value†
40.0 + 26.0
37.0 + 23.5
43.4 + 28.5
0.9832
44.6 + 30.8
38.7 + 26.1
51.1 + 34.4
0.5723
0.9993
0.9994
0.9993
p-value†
45.4 + 29.2
42.5 + 27.3
48.6 + 31.1
0.9889
Labial Injection
Insertion
Male
Female
Placement
Male
Female
Deposition
Male
Female
Lingual Injection
Insertion
Male
Female
Placement
Male
Female
Deposition
Male
Female
*Group 1
Labial and Lingual Infiltrations with Articaine
** Group 2
Labial Infiltration with Articaine plus Lingual Mock Infiltration
†
Statistical analysis performed using a repeated-measures ANOVA with Tukey-Kramer procedure.
Table 2. Mean VAS values (mm) of Procedural Discomfort Ratings
for Groups by Location of Injection, Stage of Injection, and Gender.
189
None
Mild
Moderate
Severe
Total
(N=327)
20 (6.1%)
251 (76.8%)
55 (16.8%)
1 (0.3%)
Group 1*
(N=163)
Group 2**
(N=164)
8 (4.9%)
129 (79.1%)
26 (16.0%)
0 (0.0%)
12 (7.3%)
122 (74.4%)
29 (17.7%)
1(0.6%)
2 (2.4%)
66 (80.5%)
14 (17.1%)
0 (0.0%)
6 (7.3%)
60 (73.2%)
15 (18.3%)
1 (1.2%)
6 (7.4%)
63 (77.8%)
12 (14.8%)
0 (0.0%)
6 (7.3%)
62 (75.6%)
14 (17.1%)
0 (0.0%)
9 (5.2%)
138 (80.2%)
25 (14.5%)
0 (0.0%)
11 (7.1%)
113 (72.9%)
30 (19.3%)
1 (0.6%)
Labial
Group 1
(N=82)
Group 2
(N=82)
Lingual
Group 1
(N=81)
Group 2
(N=82)
Male
(N=172)
Female
(N=155)
*Group 1
** Group 2
Labial and Lingual Infiltrations with Articaine.
Labial Infiltration with Articaine plus Lingual Mock Infiltration.
Table 3. Summary of Pain Ratings for Needle Insertion Utilizing a
Numerical Scale.
190
None
Mild
Moderate
Severe
Total
(N=327)
15 (4.6%)
225 (68.8%)
81 (24.8%)
6 ( 1.8%)
Group 1*
(N=163)
Group 2**
(N=164)
6 (3.7%)
120 (73.6%)
35 (21.5%)
2 (1.2%)
9 (5.5%)
105 (64.0%)
46 (28.0%)
4 (2.4%)
2 (2.4%)
57 (69.5%)
21 (25.6%)
2 (2.4%)
3 (3.7%)
51 (62.2%)
26 (31.7%)
2 (2.4%)
4 (4.9%)
63 (77.8%)
14 (17.3%)
0 (0.0%)
6 (7.3%)
54 (65.9%)
20 (24.4%)
2 (2.4%)
9 (5.2%)
125 (72.7%)
37 (21.5%)
1 (0.6%)
6 (3.9%)
100 (64.5%)
44 (28.4%)
5 (3.2%)
Labial
Group 1
(N=82)
Group 2
(N=82)
Lingual
Group 1
(N=81)
Group 2
(N=82)
Male
(N=172)
Female
(N=155)
*Group 1
** Group 2
Labial and Lingual Infiltrations with Articaine.
Labial Infiltration with Articaine plus Lingual Mock Infiltration.
Table 4. Summary of Pain Ratings for Needle Placement Utilizing a
Numerical Scale.
191
None
Mild
Moderate
Severe
Total
(N=327)
13 (4.0%)
196 (59.9%)
110 (33.6%)
8 (2.4%)
Group 1*
(N=163)
Group 2**
(N=164)
5 (3.1%)
102 (62.6%)
54 (33.1%)
2 (1.2%)
8 (4.9%)
94 (57.3%)
56 (34.1%)
6 (3.7%)
0 (0.0%)
47 (57.3%)
33 (40.2%)
2 (2.4%)
1 (1.2%)
35 (42.7%)
42 (51.2%)
4 (4.9%)
5 (6.2%)
55 (67.9%)
21 (25.9%)
0 (0.0%)
7 (8.5%)
59 (72.0%)
14 (17.1%)
2 (2.4%)
6 (3.5%)
111 (64.5%)
53 (30.8%)
2 (1.2%)
7 (4.5%)
85 (54.8%)
57 (36.8%)
6 (3.9%)
Labial
Group 1
(N=82)
Group 2
(N=82)
Lingual
Group 1
(N=81)
Group 2
(N=82)
Male
(N=172)
Female
(N=155)
*Group 1
** Group 2
Labial and Lingual Infiltrations with Articaine.
Labial Infiltration with Articaine plus Lingual Mock Infiltration.
Table 5. Summary of Pain Ratings for Anesthetic Deposition Utilizing
a Numerical Scale.
192
Post-injection
Time (min)
1
4
7
10
13
16
19
22
25
28
31
34
37
40
43
46
49
52
55
58
Group 1
(%)
Group 2
(%)
P value (raw)*
P value
(adjusted)†
23.2
74.4
86.6
92.7
96.3
93.9
93.9
92.7
91.5
93.9
92.7
90.2
84.1
84.1
74.4
74.4
70.7
65.9
62.2
61.0
26.8
56.1
65.9
67.1
72.0
73.2
67.1
62.2
57.3
53.7
48.8
39.0
32.9
26.8
24.4
19.5
17.1
12.2
9.8
7.3
0.6291
0.0041
0.0005
0.0001
0.0001
0.0015
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.6291
0.0408
0.0083
0.0013
0.0021
0.0209
0.0026
0.0006
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
N=82
* McNemar test used for analysis.
†
Step-down Bonferroni method of Holm adjusted for 60 comparisons.
Table 6. Between-group Comparisons of Percent 80/80 for the Lateral
Incisor.
193
Postinjection
Time (min)
Group 1
(%)
Group 2
(%)
P value
(raw)*
P value
(adjusted)†
1
4
7
10
13
16
19
22
25
28
31
34
37
40
43
46
49
52
55
58
52.4
82.9
91.5
95.1
95.1
93.9
95.1
93.9
91.5
92.7
87.8
86.6
82.9
76.8
73.2
69.5
65.9
58.5
54.9
56.1
37.8
61.0
70.7
76.8
78.0
78.0
72.0
70.7
64.6
57.3
f.6
48.8
39.0
31.7
25.6
22.0
14.6
8.5
9.8
7.3
0.0169
0.0021
0.0009
0.0015
0.0043
0.0072
0.0002
0.0003
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0878
0.0231
0.0137
0.0209
0.0408
0.0504
0.0033
0.0059
0.0015
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
N=82
* McNemar test used for analysis.
†
Step-down Bonferroni method of Holm adjusted for 60 comparisons.
Table 7. Between-group Comparisons of Percent 80/80 for the Central
Incisor.
194
Postinjection
Time (min)
Group 1
2
5
8
11
14
17
20
23
26
29
32
35
38
41
44
47
50
53
56
59
(%)
Group 2
(%)
P value
(raw)*
P value
(adjusted)†
29.3
62.2
79.3
86.6
87.8
91.5
91.5
90.2
89.0
84.1
84.1
80.5
80.5
75.6
68.3
64.6
62.2
53.7
53.7
48.8
20.7
48.8
61.0
70.7
73.2
72.0
70.7
67.1
67.1
57.3
51.2
43.9
41.5
31.7
25.6
22.0
19.5
15.9
15.9
12.2
0.1893
0.0522
0.0041
0.0146
0.0290
0.0015
0.0005
0.0003
0.0003
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.3785
0.1567
0.0408
0.0878
0.1158
0.0209
0.0083
0.0059
0.0055
0.0026
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
N=82
* McNemar test used for analysis.
†
Step-down Bonferroni method of Holm adjusted for 60 comparisons.
Table 8. Between-group Comparisons of Percent 80/80 for the Canine.
195
Tooth
Success 1*
Success 2**
Lateral Incisor
(N=82)
Group 1
Group 2
49 (59.8%)
6 (7.3%)
80 (97.6%)
62 (75.6%)
<0.0001
0.0001
46 (56.1%)
5 (6.1%)
81 (98.8%)
67 (81.7%)
p-value
Central Incisor
(N=82)
Group 1
Group 2
p-value
Canine
(N=82)
Group 1
Group 2
<0.0001
0.0005
35 (42.7%)
8 (9.8%)
76 (92.7%)
61 (74.4%)
p-value
<0.0001
0.0026
**Success #1 defined as the first of two consecutive 80/80 readings by minute 10 (for lateral and
central incisor) or by minute 11 (for canine) and maintained continuously through minute 60.
***Success #2 defined as obtaining two consecutive 80/80 readings within 60 minutes.
†
McNemar test used for analysis.
Table 9. Anesthetic Success by Group and Definition of Success.
196
Tooth
N
Group 1*
Group 2**
p-Value†
Lateral Incisor
82
2 (2.4%)
20 (24.4%)
0.0001
Central Incisor
82
1 (1.2%)
15 (18.3%)
0.0005
Canine
82
6 (7.3%)
21 (25.6%)
0.0026
*Group 1
Labial and lingual infiltrations with articaine.
**Group 2
Labial infiltration with articaine plus lingual mock infiltration.
†
McNemar test used for analysis.
Table 10. Anesthetic Failure by Tooth and Group.
197
Onset Time¹ N
†
Group 1*
Group 2**
Difference
pvalue††
Lateral Incisor
60
4.0 + 3.8
4.7 + 4.2
-0.7 + 5.2
0.0706
Central Incisor
66
3.0 + 3.9
3.9 + 3.3
-0.9 + 4.9
0.0264
Canine
57
5.0 + 3.6
6.3 + 4.5
-1.3 + 4.4
0.0286
*Group 1
Labial and lingual infiltrations with articaine.
** Group 2
Labial infiltration with articaine plus lingual mock infiltration.
†Excluded Failures.
††Wilcoxon matched pairs, signed-ranks test.
¹Onset time is measured in minutes post injections (i.e. excludes injection time of 1minute per
labial and lingual/mock injection).
Total Clinical Onset Time will include an additional 2 to 2.5 minutes.
(from start of labial infiltration)
Table 11. Mean Onset (minutes) of Pulpal Anesthesia.
198
Tooth
N
Group 1
Group 2
p-value
Short Duration*
Lateral
Central
Canine
55
63
51
19 (34.6%)
26 (41.3%)
21 (41.1%)
47 (85.4%)
57 (90.5%)
42 (82.4%)
<0.0001
<0.0001
<0.0001
Non-continuous**
Lateral
Central
Canine
60
66
57
2 (3.3%)
1 (1.5%)
2 (3.5%)
2 (3.3%)
6 (9.1%)
3 (5.3%)
1.0000
0.1250
1.0000
Slow-Onset ***
Lateral
Central
Canine
60
66
57
1 (1.7%)
1 (1.5%)
2 (3.5%)
6 (10%)
2 (3.0%)
5 (8.8%)
0.1250
1.0000
0.3750
*Short duration excluded slow onset and failures.
**Non-Continuous excluded failures.
***Slow-Onset excluded failures.
Table 12. Short Duration Anesthesia, Non-Continuous Anesthesia,
and Slow-Onset by Group and Tooth.
199
Variable
Group 1*
Group 2**
p-value†
(N=82)
(N=82)
Post Operative Day O
Male
Female
p-value†
39.7 + 30.1
51.3 + 35.1
0.2804
23.0 + 21.4
26.7 + 27.8
0.9999
<0.0001
<0.0001
Post Operative Day 1
Male
Female
p-value†
25.6 + 27.7
31.5 + 28.2
0.9900
12.0 + 18.6
18.5 + 26.2
0.9740
0.0008
0.0038
Post Operative Day 2
Male
Female
p-value†
16.2 + 14.5
19.4 + 21.1
1.0000
8.2 + 17.6
13.3 + 22.4
0.9977
0.3563
0.8375
Post Operative Day 3
Male
Female
p-value†
7.5 + 14.5
10.0 + 13.6
1.0000
6.9 + 16.1
7.5 + 15.7
1.0000
1.0000
1.0000
*Group 1
Labial and lingual infiltrations with articaine.
** Group 2
Labial infiltration with articaine plus lingual mock infiltration.
†
Statistical analysis performed using a repeated-measures ANOVA with Tukey-Kramer
procedure.
Table 13. Mean VAS values (mm) of Postoperative Discomfort
Ratings for Groups by Gender.
200
None
Mild
Moderate
Severe
Total
(N=323)
67 (20.7%)
195 (60.4%)
56 (17.3%)
4 (1.2%)
Group 1*
(N=161)
Group 2**
(N=162)
20 (12.4%)
94 (58.4%)
43 (27.1%)
3 (1.9%)
47 (29.0%)
101 (62.3%)
13 (8.0%)
1 (0.6%)
8 (10.0%)
51 (63.7%)
21 (26.3%)
0 (0.0%)
12 (14.8%)
57 (70.4%)
11 (13.6%)
1 (1.2%)
12 (14.8%)
43 (53.1%)
22 (27.2%)
3 (3.7%)
35 (43.2%)
44 (54.3%)
2 (2.5%)
0 (0.0%)
35 (20.8%)
110 (65.5%)
23 (13.7%)
0 (0.0%)
32 (20.6%)
85 (54.8%)
33 (21.3%)
4 (2.6%)
Labial
Group 1
(N=80)
Group 2
(N=81)
Lingual
Group 1
(N=81)
Group 2
(N=81)
Male
(N=170)
Female
(N=155)
*Group 1
** Group 2
Labial and lingual infiltrations with articaine.
Labial infiltration with articaine plus lingual mock infiltration.
Table 14. Summary of Pain Ratings for Post-op Day 0 Utilizing a
Numerical Scale.
201
None
Mild
Moderate
Severe
Total
(N=326)
130 (39.9%)
163 (50.0%)
32 (9.8%)
1 (0.3%)
Group 1*
(N=162)
Group 2**
(N=164)
47 (29.0%)
94 (58.0%)
20 (12.3%)
1 (0.6%)
83 (50.6%)
69 (42.1%)
12 (7.3%)
0 (0.0%)
17 (21.0%)
54 (66.7%)
10 (12.3%)
0 (0.0%)
29 (35.4%)
43 (42.1%)
10 (12.2%)
0 (0.0%)
30 (37.7%)
40 (49.4%)
10 (12.3%)
1 (1.2%)
54 (65.9%)
26 (31.7%)
2
(2.4%)
0 (0.0%)
72 (42.4%)
84 (49.4%)
13 (7.6%)
1 (0.6%)
58 (37.2%)
79 (50.6%)
29 (18.6%)
0 (0.0%)
Labial
Group 1
(N=81)
Group 2
(N=82)
Lingual
Group 1
(N=81)
Group 2
(N=82)
Male
(N=170)
Female
(N=156)
*Group 1
** Group 2
Labial and lingual infiltrations with articaine.
Labial infiltration with articaine plus lingual mock infiltration.
Table 15. Summary of Pain Ratings for Post-op Day 1 Utilizing a
Numerical Scale.
202
None
Mild
Moderate
Severe
Total
(N=323)
167 (51.7%)
142 (44.0%)
14 (4.3%)
0 (0.0%)
Group 1*
(N=160)
Group 2**
(N=163)
63 (39.4%)
92 (57.5%)
5 (3.1%)
0 (0.0%)
104 (63.8%)
50 (30.7%)
9 (5.5%)
0 (0.0%)
28 (35.0%)
49 (61.2%)
3 (3.8%)
0 (0.0%)
40 (48.8%)
34 (41.5%)
8 (9.8%)
0 (0.0%)
35 (43.8%)
43 (53.8%)
2 (2.5%)
0 (0.0%)
64 (79.0%)
16 (19.8%)
1 (1.2%)
0 (0.0%)
97 (57.7%)
66 (39.3%)
5 (3.0%)
0 (0.0%)
70 (45.2%)
76 (49.0%)
9 (5.8%)
0 (0.0%)
Labial
Group 1
(N=80)
Group 2
(N=82)
Lingual
Group 1
(N=80)
Group 2
(N=81)
Male
(N=168)
Female
(N=155)
*Group 1
** Group 2
Labial and lingual infiltrations with articaine.
Labial infiltration with articaine plus lingual mock infiltration.
Table 16. Summary of Pain Ratings for Post-op Day 2 Utilizing a
Numerical Scale.
203
None
Mild
Moderate
Severe
Total
(N=326)
210 (64.4%)
111 (34.0%)
5 (0.3%)
0 (0.0%)
Group 1*
(N=162)
Group 2**
(N=164)
97 (59.9%)
64 (39.5%)
1 (0.6%)
0 (0.0%)
113 (68.9%)
47 (28.7%)
4 (2.4%)
0 (0.0%)
46 (56.8%)
35 (43.2%)
0 (0.0%)
0 (0.0%)
45 (54.9%)
34 (41.5%)
3 (3.7%)
0 (0.0%)
51 (63.0%)
29 (35.8%)
1 (1.2%)
0 (0.0%)
68 (82.9%)
13 (15.9%)
1 (1.2%)
0 (0.0%)
116 (68.2%)
50 (29.4%)
4 (2.5%)
0 (0.0%)
94 (60.3%)
61 (39.1%)
1 (0.6%)
0 (0.0%)
Labial
Group 1
(N=81)
Group 2
(N=82)
Lingual
Group 1
(N=81)
Group 2
(N=82)
Male
(N=170)
Female
(N=156)
*Group 1
** Group 2
Labial and lingual infiltrations with articaine.
Labial infiltration with articaine plus lingual mock infiltration.
Table 17. Summary of Pain Ratings for Post-op Day 3 Utilizing a
Numerical Scale.
204
Sore to Touch
Group 1
Labial
Lingual
Group 2
Labial
Lingual
Swelling
Group 1
Labial
Lingual
Group 2
Labial
Lingual
Pain on Opening
Group 1
Labial
Lingual
Group 2
Labial
Lingual
Bruising
Group 1
Labial
Lingual
Group 2
Labial
Lingual
*Group 1
** Group 2
N
Day 0
Day 1
Day 2
162
81
81
14 (8.64%)
9 (11.1%)
5 (6.2%)
20 (12.3%)
13 (16.0%)
7 (8.6%)
11 (6.7%)
7 (8.6%)
4 (4.9%)
5 (3.1%)
2 (2.5%)
3 (3.7%)
164
82
82
12 (7.3%)
9 (11.0%)
3 (3.7%)
13 (7.9%)
11 (13.4%)
2 (2.4%)
5 (3.0%)
5 (6.1%)
0 (0%)
8 (4.9%)
8 (9.8%)
0 (0%)
162
81
81
11 (6.8%)
6 (7.4%)
5 (6.2%)
9 (5.5%)
5 (6.2%)
4 (4.9%)
0
0
0
0
0
0
164
82
82
7 (4.3%)
6 (7.3%)
1 (1.2%)
4 (2.4%)
3 (3.7%)
1 (1.2%)
3 (1.8%)
3 (3.7%)
0 (0%)
2 (1.2%)
2 (2.4%)
0 (0%)
162
81
81
5 (3.1%)
2 (2.5%)
3 (3.7%)
1 (0.6%)
0 (0%)
1 (1.2%)
0
0
0
(0%)
(0%)
(0%)
0
0
0
(0%)
(0%)
(0%)
164
82
82
1 (0.6%)
1 (1.2%)
0 (0%)
0
0
0
(0%)
(0%)
(0%)
1 (0.6%)
1 (1.2%)
0 (0%)
0
0
0
(0%)
(0%)
(0%)
162
81
81
4 (2.5%)
2 (2.5%)
2 (2.5%)
1 (0.6%)
0 (0%)
1 (1.2%)
2 (1.2%)
0 (0%)
2 (2.5%)
1 (0.6%)
1 (1.2%)
0 (0%)
164
82
82
4 (2.4%)
3 (3.7%)
1 (1.2%)
4 (2.4%)
3 (3.7%)
1 (1.2%)
4 (2.4%)
3 (3.7%)
1 (1.2%)
4 (2.4%)
3 (3.7%)
1 (1.2%)
(0%)
(0%)
(0%)
Labial and lingual infiltrations with articaine.
Labial infiltration with articaine plus lingual mock infiltration.
Table 18-1. Frequency of Subject-reported Postoperative
Complications by Day.
205
Day 3
(0%)
(0%)
(0%)
N
Sore to Chew
Group 1
Labial
Lingual
Group 2
Labial
Lingual
Headache
Group 1
Labial
Lingual
Group 2
Labial
Lingual
Nausea
Group 1
Labial
Lingual
Group 2
Labial
Lingual
Day 0
Day 1
Day 2
Day 3
162
81
81
1 (0.6%)
1 (1.2%)
0 (0%)
2 (1.2%)
0 (0%)
2 (2.5%)
0
0
0
(0%)
(0%)
(0%)
0
0
0
(0%)
(0%)
(0%)
164
82
82
0
0
0
(0%)
(0%)
(0%)
0
0
0
(0%)
(0%)
(0%)
1 (0.6%)
1 (1.2%)
0 (0%)
0
0
0
(0%)
(0%)
(0%)
162
81
81
1 (0.6%)
0 (0%)
1 (1.2%)
0
0
0
(0%)
(0%)
(0%)
0
0
0
(0%)
(0%)
(0%)
0
0
0
(0%)
(0%)
(0%)
164
82
82
0
0
0
(0%)
(0%)
(0%)
0
0
0
(0%)
(0%)
(0%)
0
0
0
(0%)
(0%)
(0%)
0
0
0
(0%)
(0%)
(0%)
162
81
81
2 (1.2%)
1 (1.2%)
1 (1.2%)
0
0
0
(0%)
(0%)
(0%)
0
0
0
(0%)
(0%)
(0%)
0
0
0
(0%)
(0%)
(0%)
164
82
82
0
0
0
0
0
0
(0%)
(0%)
(0%)
0
0
0
(0%)
(0%)
(0%)
0
0
0
(0%)
(0%)
(0%)
(0%)
(0%)
(0%)
*Group 1
Labial and lingual infiltrations with articaine.
** Group 2
Labial infiltration with articaine plus lingual mock infiltration.
Table 18-2. Frequency of Subject-reported Postoperative
Complications by Day.
206
Group 1*
Group 2**
Sore to Touch
Labial
Lingual
(N=162)
50 (30.9%)
34 (21.0%)
16 (9.3%)
(N=164)
38 (23.2%)
33 (20.1%)
5
(3.0%)
Swelling
Labial
Lingual
20 (12.3%)
11 (6.8%)
9
(5.6%)
16 (9.8%)
14 (8.5%)
2
(1.2%)
Pain on Opening
Labial
Lingual
6
2
4
(3.7%)
(1.2%)
(2.5%)
1
1
0
(0.6%)
(0.6%)
(0.0%)
Bruising
Labial
Lingual
8
6
2
(4.9%)
(3.7%)
(1.2%)
16
12
4
(9.8%)
(7.3%)
(2.4%)
Sore to Chew
Labial
Lingual
3
1
2
(1.9%)
(0.6%)
(1.2%)
1
1
0
(0.6%)
(0.6%)
(0.0%)
Headache
Labial
Lingual
1
0
1
(0.6%)
(0.0%)
(0.6%)
0
0
0
(0.0%)
(0.0%)
(0.0%)
Nausea
Labial
Lingual
2
1
1
(1.2%)
(0.6%)
(0.6%)
0
0
0
(0.0%)
(0.0%)
(0.0%)
*Group 1
** Group 2
Labial and lingual infiltrations with articaine.
Labial infiltration with articaine plus lingual mock infiltration.
Table 19. Postoperative Complications Associated with Articaine
Infiltration Injection for Groups by Location
207
APPENDIX B
FIGURES
208
Lateral Incisor Pulpal Anesthesia
Percentage of 80 Readings
100
75
Group 1
50
Group 2
25
0
1
4
7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58
Time (Minutes)
Figure 1. Percentage of 80 Readings for the Lateral Incisor by Group
and Time.
209
Central Incisor Pulpal Anesthesia
Percentage of 80 Readings
100.0
75.0
Group 1
50.0
Group 2
25.0
0.0
1
4
7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58
Time (Minutes)
Figure 2. Percentage of 80 Readings for the Central Incisor by Group
and Time.
210
Canine Pulpal Anesthesia
Percentage of 80 Readings
100.0
75.0
Group 1
50.0
Group 2
25.0
0.0
2
5
8 11 14 17 20 23 26 29 32 35 38 41 44 47 50 53 56 59
Time (Minutes)
Figure 3. Percentage of 80 Readings for the Canine by Group and Time.
211
APPENDIX C
RAW BIOGRAPHICAL DATA
212
BIOGRAPHICAL DATA
SUBJECT
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
SEX
male
male
female
male
male
male
female
female
male
male
female
female
male
male
male
female
male
male
male
male
female
female
female
male
male
male
male
male
male
male
male
male
male
male
male
male
female
male
male
male
female
AGE
26
26
24
27
26
25
24
33
28
25
24
22
25
26
25
31
29
25
27
29
29
26
25
29
25
27
27
29
26
27
27
26
23
19
28
23
23
26
26
27
23
SUBJECT
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
213
SEX
male
female
female
female
female
male
female
male
male
male
female
male
male
male
male
male
male
male
male
female
female
female
female
female
female
female
female
female
female
female
female
female
female
female
female
female
female
female
female
female
female
AGE
27
26
20
27
55
56
31
29
25
25
22
31
25
26
27
31
29
25
26
32
25
21
25
22
24
22
22
21
27
42
25
25
26
21
44
20
20
21
20
21
32
APPENDIX D
MEDICAL HISTORY FORM
214
THE OHIO STATE UNIVERSITY
COLLEGE OF DENTISTRY
Date __________________________________
Biographical Data _______________________________________________________
Chief Complaint (Why is patient seeking dental care?) ________________________
_______________________________________________________________________
Present Illness (History of Chief Complaint) _________________________________
MEDICAL HISTORY
1. Do you have or have you had any of the following?
a. rheumatic fever or rheumatic heart disease………………………..
b. heart murmur or mitral valve prolapse…………………………
c. heart disease or heart attack……………………………………
d. artificial heart valve……………………………………………
e. irregular heart beat……………………………………………..
f. pacemaker………………………………………………………
g. high blood pressure…………………………………………….
h. chest pains or angina……………………………………………
i. stroke……………………………………………………………
j. artificial joint……………………………………………………
k. hepatitis/liver disease…………………………………………..
l. tuberculosis……………………………………………………..
m. thyroid problem……………………………………………….
n. kidney disease………………………………………………….
o. diabetes (sugar)…………………………………………………
p. asthma………………………………………………………….
q. HIV or other immunosuppressive disease……………………..
r. radiation or cancer therapy……………………………………..
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
2. Do you or have you had any disease, condition, or problem not listed here?
NO
YES
3. Have you ever been hospitalized?
NO
YES
4. Have you had excessive or prolonged bleeding requiring special treatment?
NO
YES
5. Have you had an allergic reaction to any drugs or medications?
(Circle all that apply: penicillin; codeine; aspirin; anesthetics; other)
NO
YES
6. Are you currently under the care of a physician (M.D., D.O.)?
NO
When were you last seen by a physician?_________________________
Name of Physician_______________________________________
Street address___________________________________________
City, State, and Zip Code__________________________________
Phone_________________________________________________
YES
7. Are you pregnant or nursing? Estimated date of delivery_____________
NO
215
YES
8. Have you had any trouble associated with previous dental treatment?
NO
YES
9. How often do you have dental check ups? ___________ Date of last Exam_____________
10. Do you have any lumps or sores in your mouth now?
NO
YES
11. Do you smoke or use smokeless tobacco?
NO
YES
12. Are you currently taking any drugs or medications
(such as antibiotics, heart medicine, birth control pills?)
NO
YES
Current Medications
Trade Name
Generic Name
Dose/Frequency
Reason
Summary of Patient’s Medical Status:_____________________________________________
______________________________________________________________________________
______________________________________________________________________________
Medical Risk Assessment
ASA I (healthy individual)
ASA II (mild systemic disease)
ASA III (severe disease, not incapacitating)
ASA IV (incapacitating systemic disease)
Medical Consultation Required
No (healthy and/or stabilized disease)
Yes (ASA III or IV; cardiac murmur; vague hx; recent major disease; recent
diagnosis/operation; uncontrolled disease; blood pressure; etc.)
To the best of my knowledge, the above information is correct and complete.
________________________________________
Patient’s Signature
216
_________________________
Date
APPENDIX E
CONSENT
217
The Ohio State University Consent to Participate in Research
Study Title:
Anesthetic efficacy of a combination labial plus
lingual infiltration compared to a labial infiltration
using 4% articaine with 1:100,000 epinephrine in
mandibular anterior teeth.
Principal
Investigator:
Melissa Drum
Sponsor:
•
This is a consent form for research participation. It contains important
information about this study and what to expect if you decide to participate. Please
consider the information carefully. Feel free to discuss the study with your friends
and family and to ask questions before making your decision whether or not to
participate.
•
Your participation is voluntary. You may refuse to participate in this study. If you
decide to take part in the study, you may leave the study at any time. No matter what
decision you make, there will be no penalty to you and you will not lose any of your
usual benefits. Your decision will not affect your future relationship with The Ohio
State University. If you are a student or employee at Ohio State, your decision will
not affect your grades or employment status.
•
You may or may not benefit as a result of participating in this study. Also, as
explained below, your participation may result in unintended or harmful effects for
you that may be minor or may be serious depending on the nature of the research.
•
You will be provided with any new information that develops during the study
that may affect your decision whether or not to continue to participate. If you
decide to participate, you will be asked to sign this form and will receive a copy of
the form. You are being asked to consider participating in this study for the reasons
explained below.
1. Why is this study being done?
The purpose of this study is to see if an infiltration (shot next to the tooth) of articaine
(numbing solution like novocaine) to the front and back of your lower front teeth makes
your teeth anesthetized (being numb). We will compare whether a shot in the front of the
tooth will numb the tooth as well as shots in the front and back.
2. How many people will take part in this study?
One-hundred (100) people will take part in this study.
218
3. What will happen if you take part in this study?
You will receive injections (shots) of articaine with epinephrine (a numbing solution like
“novocaine”) in the front of your lower jaw. The articaine numbing solution used is not
experimental. It is routinely used in the dental office and has been approved by the FDA
for dental use. Prior to the first injection, you will be required to complete a medical
history questionnaire. A device called an electric pulp tester will be used to test your
teeth for numbness. The electric pulp tester is a battery operated device that delivers a
very small amount of current to the tooth resulting in a tingling sensation that might be
uncomfortable or cause pain in the tooth being tested and which may last up to one
second. It will be used on your teeth before the injections of numbing solution. Three of
your lower front teeth as well as a tooth on the opposite side (control tooth) will be tested
with the electric pulp tester to be sure that your teeth respond (are alive). This will take
about 6 minutes. You will have two appointments spaced at least one week apart. You
will receive a total of two injections at each appointment. After topical numbing
anesthetic has been applied to the injection (shot) site for one minute (to numb the gums),
you will receive 1.8 ml (one anesthetic cartridge) of 4% articaine with 1:100,000
epinephrine to the front surface of your lower front tooth and then you will receive 1.8
mL of 4% articaine with 1:100,000 epinephrine or a mock (placebo, fake) injection to the
back side of your front tooth. Your numb tooth and the adjacent teeth (in front and
behind this tooth) will then be pulp tested every 2 minutes for 60 minutes to determine
how well the injection (shot) gets your teeth numb. In addition, the electric pulp tester
will be used on one of your teeth on the opposite side (where you are not numb). Teeth
that are not numb or are being used as a control will experience a tingling sensation or
discomfort at which time the device will be removed immediately. Whether you receive
the articaine solution or a mock injection will be determined at random (by chance, like
flipping a coin). You will be blindfolded during these second injections. You will not
know which injection, using either the articaine numbing solution or mock injection, you
will receive. Your doctor will know which injection you receive. You will be asked to
rate the amount of pain you feel when the injections are being given. You will do this by
marking your pain experience on a line graph with a pen. You will be asked to complete
a short survey after each appointment to rate any pain or discomfort you have at the
injection site over a three-day period following each appointment. You will also report
any other side effects not relating to pain or discomfort. This survey will take about one
minute to fill out each morning.
4. How long will you be in the study?
You are aware that you will have two appointments, each will last approximately 90
minutes - 10 minutes for baseline pulp testing and filling out health information and
receiving the initial injection. Your teeth will be pulp tested for a total of 60 minutes.
The questionnaires will take about 1 minute to fill out on the day of the appointment and
for each morning for 3 days following each appointment. After completing the
questionnaires, they will be personally delivered to the endodontic clinic front office.
This will take about five minutes.
219
5. Can you stop being in the study?
You may leave the study at any time. If you decide to stop participating in the study,
there will be no penalty to you, and you will not lose any benefits to which you are
otherwise entitled. Your decision will not affect your future relationship with The Ohio
State University.
If you are a student or staff member at OSU and choose not to participate in this study,
your grades and/or employment will not be affected.
6. What risks, side effects or discomforts can you expect from being in the
study?
You may have pain associated with the local anesthetic (numbing solution) or soreness at
the site of the injections (shots) for approximately two days. Where you receive the
injection, you may have swelling (hematoma-a collection of blood in my mouth) or a
bruise may develop. You may experience a feeling of anxiety, lightheadedness or
fainting, and or a temporary increase in your heart rate. The tingling sensation and/or
slight discomfort (pain) produced by the pulp tester may be uncomfortable to you. You
may have an allergic reaction to the local anesthetic (itching or hives, very rare), or have
an unexpected infection (rare) which could result in permanent nerve damage. You may
have soreness of your gum tissue for a few days or a possible altered sensation of your lip
or tongue that may last up to a few weeks. Your tooth may feel sore to bite on for a few
days.
If you are a woman able to have children, you will be questioned regarding pregnancy or
suspected pregnancy and will not be allowed to participate if pregnant, suspect a
pregnancy, trying to become pregnant, or nursing. Additionally, you will be required to
take a urine pregnancy test before you can start this study. If you are a woman, you must
also be using a reliable method of contraception (oral contraceptives, condoms,
diaphragm, or abstinence) during the next 24 hours. The reason for excluding pregnant
or potentially pregnant women is an attempt to minimize this population in the study
because the potential risks to the fetus and nursing baby are unknown. There are no
adequate and well-controlled studies of articaine in pregnant women. This test will be
paid for by the investigator.
7. What benefits can you expect from being in the study?
You will not directly benefit from this study. Society may benefit if the infiltrations
(shots next to the tooth) of articaine makes your teeth anesthetized (being numb).
8. What other choices do you have if you do not take part in the study?
220
You may choose not to participate without penalty or loss of benefits to which you are
otherwise entitled.
If you are a student or staff member at OSU and choose not to participate in this study,
your grades and/or employment will not be affected.
9. Will your study-related information be kept confidential?
Efforts will be made to keep your study-related information confidential. However, there
may be circumstances where this information must be released. For example, personal
information regarding your participation in this study may be disclosed if required by
state law. Also, your records may be reviewed by the following groups (as applicable to
the research):
•
•
•
•
•
Office for Human Research Protections or other federal, state, or international
regulatory agencies;
U.S. Food and Drug Administration;
The Ohio State University Institutional Review Board or Office of Responsible
Research Practices;
The sponsor supporting the study, their agents or study monitors; and
Your insurance company (if charges are billed to insurance).
If the study involves the use of your protected health information, you may also be asked
to sign a separate Health Insurance Portability and Accountability Act (HIPAA) research
authorization form.
10. What are the costs of taking part in this study?
The study will pay for the cost of the study drug (articaine) and urine pregnancy test.
11. Will you be paid for taking part in this study?
Yes, you will be paid $75 for your participation. You will receive $75.00 for completing
all aspects of the study. If you are unable or unwilling to complete both sessions of the
study, you will be paid a pro-rated $30.00 per session and an additional pro-rated $7.50
per completed and returned questionnaire form. After completing the questionnaires, you
will personally deliver them to the endodontic clinic front office, at which time you will
receive payment for the completed parts of the study for which you have not yet received
payment. Payment is to compensate you for time and travel expenses. You will not be
paid for parking.
By law, payments to subjects are considered taxable income.
12. What happens if you are injured because you took part in this study?
If you suffer an injury from participating in this study, you should notify the researcher or
study doctor immediately, who will determine if you should obtain medical treatment at
The Ohio State University Medical Center.
221
The cost for this treatment will be billed to you or your medical or hospital insurance.
The Ohio State University has no funds set aside for the payment of health care expenses
for this study.
13. What are your rights if you take part in this study?
If you choose to participate in the study, you may discontinue participation at any time
without penalty or loss of benefits. By signing this form, you do not give up any personal
legal rights you may have as a participant in this study.
You will be provided with any new information that develops during the course of the
research that may affect your decision whether or not to continue participation in the
study.
You may refuse to participate in this study without penalty or loss of benefits to which
you are otherwise entitled.
An Institutional Review Board responsible for human subjects research at The Ohio State
University reviewed this research project and found it to be acceptable, according to
applicable state and federal regulations and University policies designed to protect the
rights and welfare of participants in research.
14. Who can answer your questions about the study?
For questions, concerns, or complaints about the study you may contact Dr. Melissa
Drum or Dr. Frederick Nuzum at 614 – 292-5399.
For questions about your rights as a participant in this study or to discuss other studyrelated concerns or complaints with someone who is not part of the research team, you
may contact Ms. Sandra Meadows in the Office of Responsible Research Practices at 1800-678-6251.
If you are injured as a result of participating in this study or for questions about a studyrelated injury, you may contact Dr. Melissa Drum or Dr. Frederick Nuzum at 614 – 2925399.
222
Signing the consent form
I have read (or someone has read to me) this form and I am aware that I am being asked
to participate in a research study. I have had the opportunity to ask questions and have
had them answered to my satisfaction. I voluntarily agree to participate in this study.
I am not giving up any legal rights by signing this form. I will be given a copy of this
form.
Printed name of subject
Signature of subject
AM/PM
Date and time
Printed name of person authorized to consent for
subject (when applicable)
Signature of person authorized to consent for subject
(when applicable)
Relationship to the subject
Date and time
AM/PM
Investigator/Research Staff
I have explained the research to the participant or his/her representative before requesting
the signature(s) above. There are no blanks in this document. A copy of this form has
been given to the participant or his/her representative.
Printed name of person obtaining consent
Signature of person obtaining consent
AM/PM
Date and time
Witness(es) - May be left blank if not required by the IRB
Printed name of witness
Signature of witness
AM/PM
Date and time
Printed name of witness
Signature of witness
AM/PM
Date and time
223
The Ohio State University Consent to Participate in Research
Addendum – Change in Payment Procedures for
OSU Employees Who are Research Participants
Study Title:
Principal Investigator:
Sponsor:
•
This is a consent addendum for research participation. It contains important
additional information about this study and what to expect if you continue to
participate. Please consider the information carefully. Feel free to discuss the
information with your friends and family and to ask questions before making your
decision about whether or not to continue in the study.
•
Your participation is voluntary. You may decide not to continue to take part in this
study. If you choose to continue in the study, you may leave the study at any time.
No matter what you decide, there will be no penalty to you and you will not lose any
of your usual benefits. Your choice will not affect your future relationship with The
Ohio State University. If you are a student or employee at Ohio State, your decision
will not affect your grades or employment status.
•
This consent addendum may change some of the information in the consent form
for this study that you previously signed. If you decide to continue in the study,
you will be asked to sign this addendum and will receive a copy of the signed form.
All other information in the original consent form that was not changed by this
addendum still applies. Please keep both of these forms.
If you are an OSU employee who has freely chosen to take part in this study (and it is not
a part of your job to do so), your payments were previously made through the University
payroll system and applicable taxes were deducted. New information has led to a change
in the way employees are paid. Future payments for this study will no longer be part of
your paycheck. Your future payments for this study will be made in cash or by check.
This change does not affect payments you have already received.
As before, all payments you receive (regardless of the amount) for taking part in this
study are considered by law to be taxable income.
For questions, concerns, or complaints about the study you may contact
________________.
224
If you are injured as a result of participating in this study or for questions about a studyrelated injury, you may contact _______________.
For questions about your rights as a participant in this study or to discuss other studyrelated concerns or complaints with someone who is not part of the research team, you
may contact Ms. Sandra Meadows in the Office of Responsible Research Practices at 1800-678-6251.
Signing the consent form addendum
I have read (or someone has read to me) this form and I am aware that I am being given
new information about the research study. I have had the opportunity to ask questions
and have had them answered to my satisfaction.
I voluntarily agree to participate in this study. I am not giving up any legal rights by
signing this form. I will be given a copy of this signed form.
Printed name of subject
Signature of subject
AM/PM
Date and time
Printed name of person authorized to consent for
subject (when applicable)
Signature of person authorized to consent for subject
(when applicable)
Relationship
Date and time
AM/PM
Investigator/Research Staff
I have explained the research to the participant or his/her representative before requesting
the signature(s) above. There are no blanks in this document. A signed copy of this form
has been given to the participant or his/her representative.
Printed name of person obtaining consent
Signature of person obtaining consent
AM/PM
Date and time
Witness - May be left blank if not required by the IRB
Printed name of witness
Signature of witness
AM/PM
Date and time
225
APPENDIX F
HIPAA
226
THE OHIO STATE UNIVERSITY
AUTHORIZATION TO USE
PERSONAL HEALTH INFORMATION IN RESEARCH
Title of the Study: Articaine for supplemental infiltration anesthesia in patients
with irreversible pulpitis
OSU Protocol Number:
Principal Investigator: Dr. Melissa Drum
Subject Name__________________________________________________________
Before researchers use or share any health information about you as part of this study, The Ohio
State University is required to obtain your authorization. This helps explain to you how this
information will be used or shared with others involved in the study.
•
The Ohio State University and its hospitals, clinics, health-care providers and researchers are
required to protect the privacy of your health information.
•
You should have received a Notice of Privacy Practices when you received health care
services here. If not, let us know and a copy will be given to you. Please carefully review
this information. Ask if you have any questions or do not understand any parts of this notice.
•
If you agree to take part in this study your health information will be used and shared with
others involved in this study. Also, any new health information about you that comes from
tests or other parts of this study will be shared with those involved in this study.
•
Health information about you that will be used or shared with others involved in this study
may include your research record and any health care records at the Ohio State University.
For example, this may include your medical records, x-ray or laboratory results.
Psychotherapy notes in your health records (if any) will not, however, be shared or used. Use
of these notes requires a separate, signed authorization.
Please read the information carefully before signing this form. Please ask if you have any
questions about this authorization, the University’s Notice of Privacy Practices or the study
before signing this form.
Initials/Date: _______________
227
Those Who May Use, Share And Receive Your Information As Part Of This Study
•
Researchers and staff at The Ohio State University will use, share and receive your personal
health information for this research study. Other Ohio State University staff not involved in
the study but who may become involved in your care for study-related treatment will have
access to your information.
•
Those who oversee the study will have access to your information, including:
•
•
Members and staff of the Ohio State University’s Institutional Review Boards,
including the Western Institutional Review Board
•
The Office for Responsible Research Practices
•
University data safety monitoring committees
•
The Ohio State University Research Foundation
Your health information may also be shared with federal and state agencies that have
oversight of the study or to whom access is required under the law. These may include:
•
The Food and Drug Administration
•
The Office for Human Research Protections
•
The National Institutes of Health
•
The Ohio Department of Human Services
These researchers, companies and/or organization(s) outside of The Ohio State University may
also use, share and receive your health information in connection with this study:
•
None
The information that is shared with those listed above may no longer be protected by federal
privacy rules.
Initials/Date_________
228
Authorization Period
This authorization will not expire unless you change your mind and revoke it in writing. There is
no set date at which your information will be destroyed or no longer used. This is because the
information used and created during the study may be analyzed for many years, and it is not
possible to know when this will be complete.
Signing the Authorization
• You have the right to refuse to sign this authorization. Your health care outside of the study,
payment for your health care, and your health care benefits will not be affected if you choose
not to sign this form.
•
You will not be able to take part in this study and will not receive any study treatments if you
do not sign this form.
•
If you sign this authorization, you may change your mind at any time. Researchers may
continue to use information collected up until the time that you formally changed your mind.
If you change your mind, your authorization must be revoked in writing. To revoke your
authorization, please write to:
Dr. Melissa Drum at the College of Dentistry, 305 w 12th avenue, The Ohio State University,
Columbus, Ohio 43218 or Dr. Stanley Vermilyea at the College of Dentistry, 305 w 12th
avenue, The Ohio State University, Columbus, Ohio 43218.
•
Signing this authorization also means that you will not be able to see or copy your studyrelated information until the study is completed. This includes any portion of your medical
records that describes study treatment.
Contacts for Questions
• If you have any questions relating to your privacy rights, please contact Dr. Stanley
Vermilyea at the College of Dentistry, 305 w 12th avenue, The Ohio State University,
Columbus, Ohio 43218.
•
If you have any questions relating to the research, please contact Dr. Melissa Drum at the
College of Dentistry, 305 w 12th avenue, The Ohio State University, Columbus, Ohio 43218.
Signature
I have read (or someone has read to me) this form and have been able to ask questions. All of my
questions about this form have been answered to my satisfaction. By signing below, I permit Dr.
Melissa Drum and the others listed on this form to use and share my personal health information
for this study. I will be given a copy of this signed form.
Signature________________________________________________________
(Subject or Legally Authorized Representative)
Name _____________________________________________________________
(Print name above)
(If legal representative, also print relationship to subject.)
Date___________ Time __________ AM / PM
229
APPENDIX G
VAS FORM AND RAW VAS PAIN SCORE DATA
230
None
Faint
Weak
Mild
Moderate
Strong
231
0-54 mm …….. mild pain
55-113 mm……moderate pain
114-170 mm…..severe pain
Intense
Maximum
Possible
APPENDIX H
ELECTRIC PULP TESTING FORM AND RAW EPT DATA
232
EPT Values
Date__________
Patient #______________________
Appointment # __________________
lateral
central
Code #__________________
Side_____________________
canine
Contralateral
canine
Min. Pre-test
Min. Pre-test
Base-line
•
indicates tooth will be tested with a mock electrode
lateral central canine
Contralateral
canine
1
2
3
4
5
6
7
8
*
9
10
11
12
13
233
lateral central canine
Contralateral
canine
14
15
16
17
*
18
19
20
21
22
23
24
25
26
*
27
28
29
30
31
32
33
34
234
lateral central canine
Contralateral
canine
35
*
36
37
38
39
40
41
42
43
44
*
45
46
47
48
49
50
51
52
53
*
54
55
235
lateral central canine
56
57
58
59
60
236
Contralateral
canine
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