Download Local anasthesia

Pediatric dentistry
Dr.wissam hamied
Local anesthesia
One of the most child aspects behavior guidance is the control of pain. If the
children experience pain during restorative or surgical procedures, their future as
dental patient is damaged, there fore it is important at each visit to reduce discomfort
to a minimum and to control patient situation. There are many pharmacological pain
control strategies to help children cope with these situations, both preoperatively and
post operatively. Most of these strategies involve the use of local anesthesia and / or
analgesics.
Local anesthesia can prevent discomfort that may be associated with rubber dam
clamp placements, ligating teeth, cutting tooth structure. There is no contraindication
for use local anesthesia even for youngest children.
Investigators has been found that injection anesthesia in dentistry produce greatest
negative response in children, response become increasingly negative over a series of
4 to 5 injections, thus dentist should be anticipate the need of continued efforts to
help child cope with dental injections.
Many local anesthetic agents are available to facilitate management of pain in the
dental patient. There are 2 general types of local anesthetic chemical formulations:
esters (eg, procaine, benzocaine) and amides (eg, lidocaine, mepivicaine, prilocaine,
articaine). Vasoconstrictors are added to local anesthetics to constrict blood vessels in
the area of injection. This lowers the absorption of the local anesthetic into the blood
stream, thereby lowering the risk of toxicity and prolonging the anesthetic action in
the area.
If a local anesthetic is injected into an area of infection, its onset will be delayed or
even prevented. The Inflammatory process is in area of infection, lowers the pH of
the extracellular tissue from its normal value to 5-6 lower. This low pH inhibits
anesthetic action because little of the free base form of the anesthetic is allowed to
cross into the nerve sheath to prevent conduction of nerve Impulses. Inserting a
needle into an active site of infection also could lead to possible spread of the
infection.
The selection of local anesthetic agents should be based upon:
a. the patients medical history and mental/developmental status.
b. the anticipated duration of the dental procedure.
c. the need for hemorrhage control.
d. the planned administration of other agents (eg, nitrous oxide, sedative agents,
general anesthesia)
e. the practitioners knowledge of the anesthetic agent.
Topical anesthesia.
It reduce the slight discomfort that may be associated with the insertion the needle
before the injection of local anesthesia. Some of these agents having disadvantages
that have disagreeable taste to the child, and additional time require to apply them
may allow the child become apprehensive concerning the approaching procedure.
They are available in gel, liquid, ointment and pressurized spray forms, these agents
apply to the oral mucosa membrane with cotton tipped applicators.
A variety of anesthesia agents have been used in topical anesthesia preparations
include ethylamine benzoate, butacaine sulfate, cocaine, dyclonine, lidocaine, and
tetracaine.
Jet injection.
The jet injections instrument is based on the principle that small quantity of liquid
forced through very small openings under high pressure can penetrate mucous
membrane or skin without causing tissue damaged.
It used by some dentist instead of using topical anesthesia, this method is quick and
essential painless thought the abruptness of injection may produce momentary
anxiety.
It is useful in:
1. gingival anesthesia before rubber dam clamp application for isolation.
2. used for before band application of partially erupted molars .
3. used for remove of a very loose primary tooth.
Selection of syringes and needles.
It has been established standards for aspirating syringes for use in the
administration of local anesthesia. Needle selection should allow for profound local
anesthesia and adequate aspiration. Larger gauge needles provide for less deflection
as the needle passes through soft tissues and for more reliable aspiration. The depth
of insertion varies not only by injection technique, but also by the age and size of the
patient. Dental needles are available in 3 lengths: long (32 mm), short (20 mm), and
ultra short (10mm), needle gauges range from size 23-30.
Recommendations:
1. For the administration of local dental anesthesia, dentists should select aspirating
syringes that meet the international standards.
2. Short needles may be used for any injection in which the thickness of soft tissue is
less than 20 mm and a long needle for a deeper injection into soft tissue. Any 23through 30-gauge needle may be used for intra oral injections since blood can be
aspirated through all of them however, aspiration can be more difficult when
smaller gauge needles are used. An extra-short needle is appropriate for
infiltration injections.
3. Needles should not be bent or inserted to their hub for injections to avoid needle
breakage.
Supplemental injections to obtain local anesthesia
The majority of local anesthesia procedures in pediatric dentistry involve traditional
methods of infiltration or nerve block techniques with a dental syringe, disposable
cartridges, and needles as described so far. However, several alternative techniques
are available. These include computer­controlled local anesthetic delivery,
periodontal injection techniques [ie, periodontal ligament (PDL), intraligamentary,
and periodontal injection], needle-less systems, and intraseptal or intrapulpal
injection. These techniques may improve comfort of injection by better control of the
administration rate, pressure, and location of anesthetic solutions and/or result in
successful and more controlled anesthesia. Endocarditis prophylaxis is recommended
for intraligamentary local anesthetic injections in patients at risk.
ln patients with bleeding disorders, the PDL injection minimizes the potential for
post-operative bleeding of soft tissue vessels. Intraosseus techniques may be
contraindicated with primary teeth due to potential for damage to developing
permanent teeth. Also, the use of the PDL injection or intraosseus methods is
contraindicated in the presence of inflammation or infection at the injection site.
Local anesthesia by conventional injection.
The anesthetic solution should be injected slowly and the dentist should watch the
patient closely for any evidence of an unexpected reaction.
The most common injection techniques used in treatment of children are
1. anesthesia of mandibular teeth and soft tissue.
inferior alveolar nerve block ( conventional nerve block ).
when there is deep operative or surgical procedures are under taken for
mandibular primary or permanent teeth, the inferior dental nerve block must be
blocked.
The mandibular foramen is situated at a level lower than occlusal plan of primary
teeth of the pediatric patient, there fore the injection must be made slightly lower
and most posterior than for an adults patients.
An accepted technique procedure is:
1.the thumb is laid on occlusal surface of the molar, with in the tip of the thumb
resting on the internal oblique ridge and the ball of thumb resting in the retro
molar fossa.
2. firm supporting during injection procedure can be given when the ball of
middle finger is resting on the posterior border of the mandible.
3. the parallel of syringe should be directed on plane between the two primary
molars on the opposing side of the arch.
4. it is advisable to inject a small amounts of solution as soon as the tissue is
penetrated and to continue to inject minute quantities as the needle directed
toward mandibulair foramen.
5. the depth of insertion averages about 15 mm but it varies with the size of
mandible and change with ages.
6.aproximatilly 1 mm of solution should be deposited around inferior alveolar
nerve block.
Lingual nerve block.
When you bringing the syringe to the opposite side of inferior dental nerve block
small quantity of solution should be injected this will anesthetized the lingual
nerve.
Long buccal block.
Small amount of solution should be deposited in the muco buccal fold at the point
distal and buccal to indicated tooth.
The mandibular bone of a child usually is less dense than that of an adult,
permitting more rapid and complete diffusion of the anesthetic. Mandibular buccal
infiltration anesthesia is as effective as inferior nerve block anesthesia for some
operative procedures.
2.Infiltration for the mandibuliar incisors.
If only super facial caries excavation of mandibular incisors is need or removal of
partially exfoliated primary incisors is planned, infiltration anesthesia alone may
be adequate.
Mandibular conduction anesthesia (Gow-Gates mandibular block
anesthesia ).
This depend on the external land mark to help align the needle for this injection
these are the tragus of ear and the corner of the mouth. the needle inserted just
medial to the tendon of temporal muscle and considerably superior to the insertion
point of conventional mandibulair block anesthesia.
3.Anesthesia of maxillary primary and permanent incisors and canines.
Supraperiosteal technique ( local infiltration ).
Local infiltration is used to anesthetized the primary anterior teeth. Their injection
should be made closer to the gingival margin than in the patient with permanent
teeth and the solution should deposited close to the bone. After needle tip has been
penetrated the soft tissue at the mucobucal fold, it need little advancement before
the solution is deposited ( 2mm at most ) because the apices of the maxillary
primary anterior teeth are essentially at the level of mucobuccal fold.
Before extraction of primary incisors or canines it will be necessary to anesthetize
the palatal soft tissues. The nasopalatine injection provide adequate anesthesia for
the palatal tissue of all four incisors and at least partial anesthesia of the canine
area.
4.Anesthesia to maxillary primary molars and premolars.
The middle superior alveolar nerve supply the maxillary primary molars, the
premolar, and mesiobuccal root of the first permanent molar.
The bone overlying the first primary molar is thin, and this tooth can be adequacy
anesthetized by injection of anesthetic solution opposite to the apex of root. while
for second primary molar anesthesia given to area superior to maxillary tuoberisty
area to block the posterior superior alveolar nerve this because of the thick
zygomatic bone over the buccal roots of the second primary and first permanent
molar in the primary and early mixed dentition.
To anesthetize the maxillary first and second premolar, single injection is made in
mucobuccal fold to allow the anesthesia deposited over the apex.
after buccal infiltration done, the inter dental infiltration with slow injection of
anesthetic solution as the needle penetrating the papilla, the inter dental infiltration
allows diffusion of anesthetic solution to palatal aspects via the crater like area of
inter proximal oral mucosa joining the lingual and buccal inter dental papilla.
Local anesthetic complications
Toxicity (overdose)
Most adverse drug reactions develop either during the injection or within 5- 10
minutes. Overdose of local anesthetic can result from high blood levels caused by a
single inadvertent intravascular injection or repeated injections. Local anesthetic
causes a biphasic reaction (excitation followed by depression) in the central nervous
system (CNS). Early subjective indications of toxicity involve the (CNS) and include
dizziness, anxiety, and confusion. This may be followed by diplopia, tinnitus,
drowsiness and circumoral numbness or tingling. Objective signs may include muscle
twitching, tremors, talkativeness, slowed speech, and shivering, followed by overt
seizure activity. Unconsciousness and possible respiratory arrest may occur.
The cardiovascular system (CVS) response to local anesthetic toxicity also is
biphasic. The CVS is more resistant to local anesthetics than the CNS.
Initially, during CVS stimulation, heart rate and blood pressure may increase. But as
plasma levels of the anesthetic increase, vasodilatation, followed by depression of the
myocardium with subsequent fall in blood pressure occurs. Brady cardia and cardiac
arrest may follow.
The cardio depressant effects of local anesthetics are not seen until there is a
significantly elevated local anesthetic blood level.
Local anesthetic toxicity can be prevented by careful injection technique, watchful
observation of the patient, and knowledge of the maximum dosage based on weight.
Practitioners should aspirate before every injection and inject slowly. After the
injection, the doctor, hygienist or assistant should remain with the patient while the
anesthetic begins to take effect. Early recognition of a toxic response is critical for
effective management. When signs or symptoms of toxicity are noted, administration
of the local anesthetic agent should be discontinued. Additional emergency
management is based on the severity of the reaction.
Allergy to local anesthesia
Allergic reactions are not dose dependant, but are due to the patients heightened
capacity to react to even a small dose. Allergies can manifest in a variety of ways,
some of which include urticaria, dermatitis, angioedema. fever, photosensitivity, or
anaphylaxis, Emergency managements is dependent on the rate and severity of the
reaction.
Paresthesia
Paresthesia is persistent anesthesia beyond the expected duration.
1. Trauma to the nerve can produce paresthesia, it can be caused by the needle
during the injection. The patient may experience an electric shock. in the
involved nerve distribution area.
2. Paresthesia also can be caused by hemorrhage in or around the nerve. Risk of
permanent paresthesia for 0,5%, 2% and 3% local anesthetics is 1:1,200,000
while 4% local anesthetics is 1:500,000. Reports of paresthesia are more
common with articaine and prilocaine than what is expected from their
frequency of use.
Paresthesia unrelated to surgery most often involves the tongue, followed by
the lip, and is more common with 4% solutions of articaine or prilocaine. Most
cases resolve in 8 weeks. Post-operative soft tissue injury, Self-induced soft tissue
trauma is an unfortunate clinical complication of local anesthetic use in the oral
cavity. Most lip and cheek biting lesions of this nature are self-limiting and heal
without complications, although bleeding and infection possibly may result.
Post anesthetic trauma prevention:
- Remind both parent and child that area will remain numb after the appointment.
- Caution that child should not to chew, bite or pick at area.
- Extremely important for young children and "first timers",
- Sometimes placing a cotton roll between the teeth will help
remind patient not to chew.