Download comparison of soft tissue and dentoalveolar effects of the tad

COMPARISON OF SOFT TISSUE AND DENTOALVEOLAR EFFECTS OF THE
TAD-SUPPORTED DISTAL JET VERSUS UPPER PREMOLAR EXTRACTIONS
Evmorfia Fotakidou, D.D.S
A Thesis Presented to the Graduate Faculty of
Saint Louis University in Partial Fulfillment
of the Requirements for the Degree of
Master of Science in Dentistry
2015
COMMITTEE IN CHARGE OF CANDIDACY:
Associate Professor Ki Beom Kim
Chairperson and Advisor
Professor Eustaquio A. Araujo
Associate Clinical Professor Donald R. Oliver
i
DEDICATION
To my father, whose endless support and faith in me,
have followed me throughout my life and have allowed me to
pursue my dreams.
To my mother, for all her constant and unconditional
love, patience and advice.
To my brother, for being the voice of reason and my
reality check when needed.
To all my friends and teachers over time, for
inspiring me to always reach for more.
Finally, to all the people who struggle to realize
their dreams despite all odds.
ii
ACKNOWLEDGEMENTS
This project was completed with the help of the
following individuals:
Dr. Ki Beom Kim, for his patience, encouragement and
advice with the topic selection.
Dr. Eustaquio Araujo, for his help and advice on this
project and in the clinic.
Dr. Donald Oliver, for his continuous support and for
his meticulous corrections on this project.
Dr.Heidi Israel and Dr.Vasilis Charalampakis, for
their help with the statistics.
Dr.Jay S. Bowman for providing part of my sample and
for keenly answering all my querries.
Dr.Behrents, for the oppportunity to pursue my
orthodontic education at Saint Louis University.
Finally I would like to thank the rest of the faculty
for contributing to my orthodontic education, my coresidents for sharing this educational experience and the
staff members for making my residency at SLU,CADE
pleasant as possible.
iii
as
TABLE OF CONTENTS
ABSTRACT....................... Error! Bookmark not defined.
LIST OF TABLES............................................ v
LIST OF FIGURES.......................................... vi
CHAPTER 1: REVIEW OF THE LITERATURE....................... 1
Angle’s classification .................................. 1
Class II Division 1 ..................................... 2
Etiology of Class II malocclusion ....................... 3
Epidemiology of Class II malocclusion ................... 5
Class II correction ..................................... 7
Treatment options for Class II Division 1 .............. 10
Extraction of Maxillary premolars .................... 10
Distalization ........................................ 15
TADs in orthodontics ................................. 18
TAD-supported distalizers .............................. 19
TAD-supported Horseshoe Distal Jet ................... 21
Statement of Thesis .................................... 23
References ............................................. 25
CHAPTER 2: JOURNAL ARTICLE...............................
Abstract ...............................................
Introduction ...........................................
Material and Methods ...................................
Sample ...............................................
Methodology ..........................................
Statistical Analysis .................................
Reliability ..........................................
Results ................................................
Pre-Treatment Measurements ...........................
Treatment Changes ....................................
Discussion .............................................
Limitations ..........................................
Results compared to the literature ...................
Conclusions ............................................
References .............................................
30
30
32
36
36
38
42
42
43
43
45
51
52
53
58
59
Appendix................................................. 62
Vita Auctoris............................................ 65
iv
LIST OF TABLES
Table 2.1
Sample characteristics....................37
Table 2.2
Pre-treatment measurements................45
Table 2.3
Treatment changes for U4s extraction group
.........................................47
Table 2.4
Treatment changes for the Distal Jet group
.........................................48
Table 2.5
Treatment change between U4s and DJ
group.....................................51
Table A.1
Landmarks and definitions.................63
Table A.2
Descriptive statistics for U4s group......64
Table A.3
Descriptive statistics for the DJ group...65
v
LIST OF FIGURES
Figure 1.1
Class II Division 1 example.............2
Figure 1.2
TAD-supported Distal Jet................24
Figure 2.1
TAD-supported Distal Jet................38
Figure 2.2
Anatomical landmarks and reference
planes..................................39
Figure 2.3
Horizontal linear measurements..........40
Figure 2.4
Vertical Linear measurements............41
vi
CHAPTER 1: REVIEW OF THE LITERATURE
Angle’s classification
The need to improve smile esthetics and to achieve
facial harmony and balance, has led to the flourishing of
many aspects of the medical profession and hence, to
orthodontics as well. It was in fact, in the 1890s when
Edward H. Angle defined the characteristics of the ideal
occlusion in the permanent dentition, that the basic
principles of orthodontics were established. With his work,
Angle classified the three types of malocclusions and their
divisions and subdivisions “as indicated by the relation of
the lower first molars with the upper first molars-the keys
to occlusion"1.
True to Angle’s classification, a dental relationship
in which the mesiobuccal cusp of the upper first permanent
molar occludes in the buccal groove of the lower first
molar, defines a Class I molar relationship. Any variation
in that dental relationship, results in a Class II or a
Class III malocclusion, where the lower arch is distal or
mesial to normal in its relation to the upper arch,
accordingly.
1
Class II Division 1
The main characteristic of a Class II Division 1
malocclusion is the distal relation of the lower dentition
to the upper to the extent of more than one-half the width
of one cusp, as described by Angle1. This clinical phenotype
is often accompanied by protruding incisors, a narrow upper
arch, a short and inactive upper lip and sometimes a mouthbreathing habit (Figure 1.1). Despite the dental traits
though, an underlying craniofacial element might also
contribute to the clinical characteristics of a Class II
Division 1 malocclusion.
Figure 1.1: Example of a Class II Division 1 dental
relationship
2
Etiology of Class II malocclusion
The etiology of Class II malocclusion has been a much
debated issue amongst clinicians and researchers and has
indeed been thoroughly investigated. In 1981, McNamara
carried out a cross-sectional study, evaluating the lateral
cephalograms of 277 Class II patients, aged eight to ten
years, in order to determine the frequency of occurrence of
the factors contributing to their Class II malocclusion2.
According to McNamara, there are four main elements
causing the Class II characteristics: the maxillary
skeletal position, the maxillary dental position, the
mandibular skeletal position and the mandibular dental
position. In that study, the main cause of the Class II
malocclusion was a retrusive mandible (in 60% of the cases)
with typically normally positioned lower incisors. The
maxilla was usually normally positioned but even in the
cases where it was in an abnormal position, there was a
tendency for a maxillary retrusion rather than a maxillary
protrusion. Another interesting finding of this study was
that the upper dentition was far less protrusive than what
was reported in other studies. The conclusion of the
project was that the etiology of the Class II malocclusion
is multifactorial and a result of as many as 77 different
3
combinations and/or variations between the skeletal and
dental components2.
Another more recent study by Freitas and
coworkers3, compared the apical bases, the dental and also
the cranial characteristics of 55 Brazilian Class II
Division 1 adolescents to a controlled group. The findings
of the study are in agreement with the McNamara study, as
the AP position and the length of the maxilla was similar
between the two groups whereas it was the mandible that was
found to be smaller in length and also more retruded in
relation to the cranial base for the test group rather than
the control. The upper incisors in the test group were more
labially inclined yet similarly positioned as in the
control group, in contrast to the lower incisors that were
more proclined for the test group.
4
Epidemiology of Class II malocclusion
Class II malocclusion is a very common finding and
probably one of the most common reasons why patients seek
orthodontic treatment. The underlying genetic basis of the
Class II malocclusion can be apparent in people of the same
kin or origins and could explain the variability of its
prevalence within different ethnic groups. For example,
Thilander and coworkers reported that 20.8% of the children
and adolescents in a Bogotanian population exhibited a
Class II malocclusion (Class II Division 1 in 14.9% and
Class II Division 2 in 5.9%)4. Another study by BorzabadiFarahani and coworkers, determined that the prevalence of
Class II Division 1 and Class II Division 2 malocclusion
was 24.1% and 3.4% respectively, in an Iranian adolescent
population5. In another study, the frequency of a Class II
Division 1 malocclusion in Turkish adolescents was found to
be as high as 40% of the population6, compared to a 14.7% in
a Nigerian adolescent sample7.
In 1990, El-Mangoury and Mostafa studied 501 adult
Egyptians in order to determine whether there was a
difference in the prevalence of dental malocclusion between
different ethnic groups and also between males and females8.
They found that the occurrence of Class II malocclusion was
5
21% for the given population, but when compared to other
studies, they concluded that the frequency of Class II
malocclusion can be ranked in descending order to the
following ethnic groups: Caucasian-Americans, Danes,
Egyptians, British, African-Americans, Finns, Polynesians,
Indians, Eskimos, Kenyans and Swedish. Results from the
same study, indicate that occlusal variation frequencies
were significantly different for females and males for
Angle Class I and Class III malocclusion but not for Class
II malocclusion which showed similar prevalence in both
sexes.
Even though the variation of the Class II prevalence
depends on the population, when it comes down to Caucasians
there is no doubt that it is the second most frequent
malocclusion9. Indeed, when Massler and Frankel conducted an
epidemiologic study in 2758 high school US students, they
reported that 19.4% of the sample had a Class II
malocclusion and most of them had a Class II Division 1
pattern (16.7%)10.
Even more recent data though, as those collected from
the study by the National Health and Nutrition Estimates
Survey
(NHANES III) for the period 1988-1991, suggest that
in the 7000 subjects, who were studied at the time ,23% of
6
the children,15% of the adolescents and 13% of the adults,
exhibited a Class II malocclusion.
Class II correction
In order to describe and explain the different methods
of Class II correction, a basic understanding of the Class
II growth pattern is essential. “The cephalocaudal growth
pattern” as described by Proffit9, in which more growth
occurs in the lower extremities rather than the upper, also
applies in the craniofacial complex. Indeed, the mandible
shows accelerated growth (also known as differential
growth) later in time compared to the maxilla, thus
contributing to the correction of a Class II malocclusion.
However, as Proffit points out, it is unrealistic to expect
a Class II correction of more than 3-4 mm solely by the
differential growth pattern of the mandible.
Depending on the treatment objectives and the
etiology, there are many methods that can be used for a
Class II correction that can either address the
dentoalveolar aspect, the skeletal underlying component of
a Class II malocclusion or a combination of the two. For
example, when treatment planning for the correction of a
severe Class II case with a profound skeletal discrepancy,
the best treatment option would be orthognathic surgery
7
involving a single or both jaws, in order to improve facial
attractiveness and dental relationships11.
For cases where growth modification is required, a
variety of functional appliances (MARA, AdnvanSync, Herbst,
Twin Bock, etc.) can be used in order to promote a forward
posture of the mandible, while restraining the maxilla
during the patient’s growth peak. Even though there is no
convincing evidence as to whether the functional appliances
succeed in significantly increasing the final size of the
mandible in Class II mandibular retrognathic patients12,
they have been found to be effective in correcting the
dental and the sagittal maxillomandibular relationship13.
Another treatment option, especially in cases where an
orthopedic effect is desired, is the application of extra
oral traction with a headgear. Even though initially, it
was thought to have merely a dental impact -distalization
the maxillary molars-, later studies reported a skeletal
effect as well. In fact, several studies14,
15
evaluated
post-treatment cephalograms of Class II patients who had
been wearing a headgear and compared them to cephalograms
of untreated Class II patients, yet the same conclusion was
drawn: a restriction of the horizontal maxillary growth was
evident and the correction of the Class II was accomplished
8
as a result of the forward displacement of the mandible due
to its differential growth.
Another alternative, is the application of interarch
elastics or appliances (ForsusTM, PowerScope, etc.) that can
be successfully used for treating Class II cases as a
result of their dentoalveolar effects on both arches16. As a
matter of fact, the sagittal improvement of the
maxillomandibular relationship is improved because of the
combination of a distal and a mesial force, applied on the
upper and the lower dentition respectively, resulting
mainly in proclination of the lower incisors17,
18
.
It is also common to apply a variety of extraction
patterns in order to camouflage skeletal discrepancies and
to improve both the patients’ profile but also their dental
relationships. A typical extraction pattern for Class II
cases is probably the extraction of upper and lower
premolars especially in cases when alleviating some amount
of crowding is also desirable. In cases with excessive
overjet, proclined upper incisors, minor crowding in the
lower arch and little to no remaining growth potential,
extraction of two maxillary premolars might be the optimal
extraction pattern9. This treatment modality allows for
efficient reduction of the overjet, retraction of the upper
9
incisors and soft tissue improvement while achieving a
Class I canine with a Class II molar relationship.
Finally, in cases with a good skeletal relationship
where there is mild/moderate crowding and Class II molar
correction is required, molar distalization is indicated9.
Appliances like the Pendulum, the Distal Jet, the Frog,
etc. are used to apply continuous, distally-directed forces
on the maxillary dentition, thus achieving a combination of
molar tipping and translation into a Class I while
eliminating patient compliance issues.
Evidently, there is no panacea for treating Class II
patients and all of the above mentioned treatment options
can be effective in the hands of a skilled clinician. The
treatment choice depends on the etiology of the problem,
the clinician’s technical knowledge and personal preference
and the unique attributes of each case like the patient’s
age, profile, dental and skeletal relationships,
compliance, etc.
Treatment options for Class II Division 1
Extraction of Maxillary premolars
When a Class II Division 1 malocclusion presents
certain clinical characteristics like only a mild skeletal
discrepancy, increased overjet, mild crowding on the lower
10
arch, “end-to-end” Class II molar relationship and when the
patient has minimal remaining growth potential, extraction
of the first maxillary premolars only, is indicated9. The
final result of this treatment modality is a Class I canine
and a Class II molar relationship with a reduced overjet
due to the retraction of the upper anterior teeth. When
needed the lower incisors can also be slightly protruded
thus, reducing the need for maximum retraction of the upper
anterior teeth19. However, if the Class II malocclusion is
due to a deficient mandible, extracting two maxillary
premolars only might result in unfavorable changes to the
patient’s profile, as Proffit points out9.
This extraction pattern, also known as camouflage
treatment, leads to a non-ideal molar relationship as it
does not follow Angle’s definition of the ideal occlusion1.
However, the final outcome is a stable and acceptable
occlusion as reported by many studies in the literature20-23.
As a matter of fact, Janson and coworkers used the priority
treatment index (TPI) to compare the initial and final
dental models of 81 Class II patients treated with two
maxillary premolar extractions versus 50 Class II patients
treated with four premolar extractions. They concluded that
the two premolar extraction protocol resulted in a better
11
occlusal success rate as the final overjet, overbite, TPI
and AP canine discrepancy were significantly smaller
compared to the four premolar extractions group22.
This finding is in accordance with two follow up
studies21,
23
, by Janson and coworkers who studied initial,
final and post retention dental casts and cephalometric Xrays of two groups of
Class II patients, one treated with
extraction of two maxillary premolars and other with
extraction of four premolars21. Using Little’s irregularity
index, the TPI and cephalometric variables, the researchers
concluded that both extraction protocols had similar longterm post-treatment stability 5 and even 9 years after
active treatment.
Similar are the findings reported from studies
comparing correction of Class II malocclusion between nonextraction and maxillary premolar extraction groups. When
Janson and his research group compared the dental models of
69 upper premolar extraction cases to those of 43 nonextraction cases using the peer assessment rating (PAR)
index, they concluded that the occlusal success rate was
greater for the extraction group24. The researchers
attribute their findings to the diminished anchorage
control requirements and patient compliance when two
12
maxillary premolars are extracted thus, resulting in better
AP relationship. In fact, they support the claim that the
suggested extraction pattern might be more efficient than
the non-extraction protocol for patients with more severe
anteroposterior molar relationships20.
Even though there is some evidence that supports the
stability of the maxillary premolar extraction protocol,
there are not many studies in the literature about the soft
tissue and dentoalveolar effects of this treatment
modality. A project by Bokas and Collett attempted to shed
some light on this question by studying the initial and
final cephalograms of 35 Class II Division 1 patients with
a mean age of 13.05 years, treated with extractions of two
maxillary premolars25. According to their findings, there
was a small but not clinically significant reduction in the
upper lip protrusiveness, a decrease in the ANB angle by
1.42 degrees on average and a mean reduction of the overjet
by 6.42mm. As a result, they concluded that upper premolar
extractions do not result in a flattening of the facial
profile and that other factors related to the lip
morphology have a stronger correlation to the posttreatment lip position.
13
Another study by Janson and coworkers examined the
soft tissue changes in Class II Division 1 cases treated
non-extraction versus upper premolar extractions. A total
of 44 patients were equally allocated in the two groups
that were matched for age but exhibited a slight difference
of 0.6mm in the initial amount of overjet26.
According to
the results, only one soft tissue variable- the lower lip
protrusiveness- showed a significant post-treatment change,
with the non-extraction group showing a moderately
increased lower lip protuberance compared to the extraction
group. Other than that, both groups showed similar posttreatment soft tissue effects.
On the contrary, when Almeida-Pedrin and coworkers,
compared the cephalograms of 82 Class II patients treated
with extraction of upper premolars, the Pendulum appliance
and the cervical headgear, they reported that the first
group showed greater upper lip retrusion compared to the
other two treatment modalities27. Apart from that, they
found that other soft tissue variables, like the
nasiolabial angle and the position of the lower lip had
similar changes in all three groups, thus reaching the
conclusion that the three different treatment approaches
14
were similar and did not significantly affect the facial
profiles.
To sum up, there is inconclusive data in the
literature about the impact of the upper premolar
extraction pattern. Nonetheless, there are certain benefits
to the above mentioned extraction pattern that are hard to
ignore such as: a) the retraction of the anterior upper
teeth which can improve facial characteristic, b)the
decreased biomechanical considerations due to the reduced
anchorage requirements, c)the reduced lower incisor
proclination as there is moderate need for Class II
mechanics and d) the additional space provided on the
posterior segments of the upper dentition that allows for
the unhindered eruption of the upper second and third
molars which otherwise, could be impacted28.
Distalization
Another alternative for the correction of a Class II
malocclusion when there is mild to moderate arch length
discrepancies and relatively good skeletal relationships,
is the distal movement of the upper dentition that is
highly effective (up to 90% successful ) in the late mixed
dentition stage before the eruption of the maxillary second
molars29. First, the maxillary first molar is moved
15
distally, followed by the second and first premolars
respectively and finally the canines into an ideal Class I
relationship. Even though, this treatment sequence might
not seem to be biomechanically strenuous, it is actually
challenging to maintain the distal position of the upper
first molars while they serve as an anchorage unit for the
retraction of the incisors30. This is why, molar
overcorrection up to 2mm is often advocated as well as
postponing the retraction of the other teeth for about 4-5
months29.
There are many appliances that can be used in order to
distalize the upper dentition, such as the conventional
intra-arch palatally supported appliances (i.e. the Distal
Jet, the pendulum, the frog, etc.)as well as magnets, NiTi
coil springs, etc. All of these appliances do not require
patient cooperation and ensure the application of
continuous forces to the upper dentition.
Even though this treatment modality has many benefits,
it also comes with certain unwanted dental effects like an
increase in the amount of overjet due to the anterior
anchorage loss. In fact, it has been reported in the
literature that the Class II correction is a result of the
distal movement of the posterior teeth but also a result of
16
anterior anchorage loss and increase in the overjet31, which
might negatively affect facial esthetics by increasing lip
protrusiveness. Another study by Kaplan compared the
initial and final cephalograms of 150 Class II Division 1
patients, treated with either a headgear, conventional
Distal Jet or maxillary premolar extractions. According to
the results, the maxillary incisors were more protruded and
the upper and lower lip retruded the least in the Distal
Jet group32.
Another disadvantage of some distalizing appliances is
the tipping rather than the bodily distal movement of the
maxillary molars. A study by Gulati and coworkers evaluated
the dental and skeletal effects of molar distalization
using the Jones Jig appliance and they reported increased
distal tipping and distopalatal rotation of the maxillary
first molars. What is more, the appliance caused a
statistically significant clockwise rotation of the
mandibular plane angle because of the extrusion of the
upper first molars. This finding, led the researchers to
contraindicate the clinical application of the appliance
for patients with high mandibular plane angle33.
In an attempt to overcome some of these side effects
of the conventional distalizing appliances and with the
17
increasing popularity and application of Temporary
Anchorage Devices (TADs) in orthodontics, the TAD-supported
distalizers were introduced in the daily practice.
TADs in orthodontics
Orthodontic anchorage and its importance have been
understood for a long time, but it wasn’t until 1923 that
it was defined as “the base against which orthodontic force
or reaction of force is applied”34. Maintaining orthodontic
anchorage can be crucial, especially in order to
successfully treat Class II cases and that is why
clinicians and researchers have been trying to come up with
effective ways to do so, with skeletal anchorage being such
an example.
The concept of osseo-integration has been associated
with Branemark, who realized that bone had a high affinity
for titanium35. After this finding, it wasn’t long before
the contemporary implants were designed and used in
orthodontics as a means of maintaining anchorage, among
other applications as well35,
36
. The first successful
clinical application of skeletal anchorage devices in
orthodontics was reported in 1983 by Creekmore and Eklund37,
yet it took a long time before the contemporary devices
18
gained their current, widespread application in the daily
practice.
According to Cope’s definition of a temporary skeletal
anchorage device (TAD), it is a device temporarily fixed to
the bone so as to “enhance orthodontic anchorage either by
supporting the teeth of the reactive unit or by obviating
the need for the reactive unit altogether, and which is
subsequently removed after use38. TADs are nowadays used to
intrude or extrude teeth, to close spaces, to retract or
distalize teeth and they increase treatment efficiency by
eliminating patient compliance and anchorage stability.
TAD-supported distalizers
The effectiveness of orthodontic distalizing
appliances reinforced with the temporary anchorage devices
has been debated as there are controversial data in the
literature. Several studies39-41 have indicated maxillary
first molar distalization (from 3.9mm40 to 6mm39) and distal
tipping (from 8.840 to 11.339 degrees) but no significant
changes in overjet, overbite and mandibular plane angle.
Another study by Kinzinger and coworkers compared the
initial and final cephalograms and dental models of 10
Class II patients treated with a TAD-supported Distal Jet42.
According to the findings even though the appliance did not
19
maintain stationary anchorage, it was effective in
producing translatory distal movement of the maxillary
molars.
In the study by Polat-Ozsoy and others43, measurements
of initial and final cephalograms of 22 Class II patients
treated with a bone-anchored pendulum appliance (BAPA) were
compared to those of 17 cases treated with the conventional
pendulum (CPA). The researchers concluded that the mean
distal movement of the upper molars was 4.8mm for the first
group and 2.7mm for the second group. The BAPA group had
increased distal molar tipping (9.3o) compared to the CPA
group (5.3o). However, the first group showed upper incisor
retraction whereas in the CPA group a statistically
significant incisor proclination was noted.
A systematic review of the literature by Fudalej and
Antoszewska44 evaluating the final outcome of TAD-supported
distalizers, reported reduced side effects compared to
conventional distalizers. In effect, a greater amount of
molar distalization was noted while the initial position of
the maxillary incisors remained unchanged. The researchers
attributed the increased distal movement to the greater
pressure on the maxillary molars compared to the force
20
produced by the tooth borne appliances which is also
distributed to the anterior teeth.
TAD-supported Horseshoe Distal Jet
The TAD-supported Horseshoe Distal Jet as modified by Dr.
Bowman, is supported by skeletal anchorage only, without an
acrylic palatal button. The temporary skeletal anchorage
devices -usually 1.5-2 mm in diameter and 6-8 mm in lengthare placed in the palatal alveolus between the first molar
and second premolar under local anesthesia. The TADs can be
attached to hooks on the anterior part of the tracking wire
with steel ligature wires (Figure 1.2). The appliance is
cemented on the upper first molars and according to the
activation protocol, the springs are activated a quarter
turn each time and the patient is seen at a 4-week interval
over a period of 4-5 months45. Once the distalization has
been accomplished, the Horseshoe Jet is converted to a TADsupported holding arch for indirect anchorage during the
retraction of the incisors.
The goal of the TAD-supported Distal Jet is to reduce
the anchorage loss and some of the unwanted effects of the
conventional Distal Jet like the upper incisor flaring and
the molar tipping, as indicated from other studies in the
literature comparing various TAD-supported versus tooth
21
borne distalizing appliances. Nonetheless, there is
conflicting evidence as well, thus it is difficult to
arrive to a conclusion.
Indeed, a study by Baumgartner46, superimposed the
initial and final cephalometric X-rays of 54 patients in
total treated with the conventional or the TAD-supported
Distal Jet, both followed by traditional orthodontic fixed
appliances. The findings of the study suggest that there
was no significant difference in the overjet change and the
upper incisor movement and angulation. Both appliances
produced a similar amount of distal movement and tipping of
the upper molars and had similar total treatment duration.
The only significant difference was reported in the lower
molar position as in the conventional appliance group, a
mesial movement (mean 1.25mm) was observed whereas in the
TAD-supported Distal Jet group the lower molars drifted
distally (mean -0.52mm).
These findings are in accordance with a study by
Cozzani and others47, who compared the efficiency of molar
distalization between two groups of 18 subjects treated
with the conventional or the MI supported Distal Jet. This
group of researchers confirmed that both appliances had
similar treatment duration and similar molar distalization
22
effects. Apart from that, the results of the study showed
that the maxillary first premolars distalized spontaneously
in the MI supported Distal Jet group, while in the other
group a slight mesial movement was noted.
Statement of Thesis
There are many studies in the literature evaluating the
treatment effects of conventional distalizing appliances to
upper premolars extractions while there are many others
that compare mini-implant supported distalizers to their
tooth borne equivalent appliance. However, to my knowledge,
there are no studies directly assessing the treatment
outcomes of Class II Division 1 patients treated with the
mini-screw supported Distal Jet versus maxillary premolar
extraction
cases. The present study will therefore,
directly compare the dentoalveolar and soft tissue effects
of these two treatment options in an attempt to further
contribute to the current knowledge regarding the two
treatment modalities.
23
Figure 1.2: TAD-supported Horseshoe Distal Jet ( photo
courtesy of Dr. S. Jay Bowman45)
24
References
1. Angle EH. Treatments of Malocclusion of the Teeth. 7th
ed. Philadelphia: S.S. White Dent. Mf. Co.; 1907.
2. McNamara JA, Jr. Components of class II malocclusion in
children 8-10 years of age. Angle Orthod.
1981;51:177-202.
3. Freitas MR, Santos MA, Freitas KM, Janson G, Freitas DS,
Henriques JF. Cephalometric characterization of
skeletal Class II, division 1 malocclusion in white
Brazilian subjects. J Appl Oral Sci. 2005;13:198203.
4. Thilander B, Pena L, Infante C, Parada SS, de Mayorga C.
Prevalence of malocclusion and orthodontic treatment
need in children and adolescents in Bogota, Colombia.
An epidemiological study related to different stages
of dental development. Eur J Orthod. 2001;23:153-67.
5. Borzabadi-Farahani A, Borzabadi-Farahani A, Eslamipour
F. Malocclusion and occlusal traits in an urban
Iranian population. An epidemiological study of 11- to
14-year-old children. Eur J Orthod. 2009;31:477-84.
6. Gelgor IE, Karaman AI, Ercan E. Prevalence of
malocclusion among adolescents in central anatolia.
Eur J Dent. 2007;1:125-31.
7. Isiekwe MC. Malocclusion in Lagos, Nigeria.
Dent Oral Epidemiol. 1983;11:59-62.
Community
8. El-Mangoury NH, Mostafa YA. Epidemiologic panorama of
dental occlusion. Angle Orthod. 1990;60:207-14.
9. Proffit WR FH, Sarver DM. Contemporary orthodontics. 5th
ed. St.Louis,MO: Mosby Eslevier; 2012.
10. Massler M, Frankel JM. Prevalence of malocclusion in
children aged 14 to 18 years. Am J Orthod.
1951;37:751-68.
11. Graber LW VR, Vig KWL. Orthodontics: Current principles
and techniques. 5th ed. Philadelphia: Mosby Elsevier;
2012.
25
12. Pancherz H. The effects, limitations, and long-term
dentofacial adaptations to treatment with the Herbst
appliance. Semin Orthod. 1997;3:232-43.
13. Schaefer AT, McNamara JA, Jr., Franchi L, Baccetti T.
A cephalometric comparison of treatment with the Twinblock and stainless steel crown Herbst appliances
followed by fixed appliance therapy. Am J Orthod
Dentofacial Orthop. 2004;126:7-15.
14. Firouz M, Zernik J, Nanda R. Dental and orthopedic
effects of high-pull headgear in treatment of Class
II, division 1 malocclusion. Am J Orthod Dentofacial
Orthop. 1992;102:197-205.
15. Freitas MR, Lima DV, Freitas KM, Janson G, Henriques
JF. Cephalometric evaluation of Class II malocclusion
treatment with cervical headgear and mandibular fixed
appliances. Eur J Orthod. 2008;30:477-82.
16. Cacciatore G, Alvetro L, Defraia E, Ghislanzoni LT,
Franchi L. Active-treatment effects of the Forsus
fatigue resistant device during comprehensive Class II
correction in growing patients. Korean J Orthod.
2014;44:136-42.
17. Janson G, Sathler R, Fernandes TM, Branco NC, Freitas
MR. Correction of Class II malocclusion with Class II
elastics: a systematic review. Am J Orthod
Dentofacial Orthop. 2013;143:383-92.
18. Cacciatore G, Ghislanzoni LT, Alvetro L, Giuntini V,
Franchi L. Treatment and posttreatment effects
induced by the Forsus appliance: A controlled clinical
study. Angle Orthod. 2014;84:1010-7.
19. Stalpers MJ, Booij JW, Bronkhorst EM, Kuijpers-Jagtman
AM, Katsaros C. Extraction of maxillary first
permanent molars in patients with Class II Division 1
malocclusion. Am J Orthod Dentofacial Orthop.
2007;132:316-23.
20. Janson G, Graciano JT, Henriques JF, de Freitas MR,
Pinzan A, Pinzan-Vercelino CR. Occlusal and
cephalometric Class II Division 1 malocclusion
severity in patients treated with and without
extraction of 2 maxillary premolars. Am J Orthod
Dentofacial Orthop. 2006;129:759-67.
26
21. Janson G, Leon-Salazar V, Leon-Salazar R, Janson M, de
Freitas MR. Long-term stability of Class II
malocclusion treated with 2- and 4-premolar extraction
protocols. Am J Orthod Dentofacial Orthop.
2009;136:154.e1-10; discussion -5.
22. Janson G, Brambilla Ada C, Henriques JF, de Freitas MR,
Neves LS. Class II treatment success rate in 2- and
4-premolar extraction protocols. Am J Orthod
Dentofacial Orthop. 2004;125:472-9.
23. Janson G, Busato MC, Henriques JF, de Freitas MR, de
Freitas LM. Alignment stability in Class II
malocclusion treated with 2- and 4-premolar extraction
protocols. Am J Orthod Dentofacial Orthop.
2006;130:189-95.
24. Janson G, Barros SE, de Freitas MR, Henriques JF,
Pinzan A. Class II treatment efficiency in maxillary
premolar extraction and nonextraction protocols. Am J
Orthod Dentofacial Orthop. 2007;132:490-8.
25. Bokas J, Collett T. Effect of upper premolar
extractions on the position of the upper lip.
Orthod J. 2006;22:31-7.
Aust
26. Janson G, Fuziy A, de Freitas MR, Castanha Henriques
JF, de Almeida RR. Soft-tissue treatment changes in
Class II Division 1 malocclusion with and without
extraction of maxillary premolars. Am J Orthod
Dentofacial Orthop. 2007;132:729.e1-8.
27. de Almeida-Pedrin RR, Henriques JF, de Almeida RR, de
Almeida MR, McNamara JA, Jr. Effects of the pendulum
appliance, cervical headgear, and 2 premolar
extractions followed by fixed appliances in patients
with Class II malocclusion. Am J Orthod Dentofacial
Orthop. 2009;136:833-42.
28. S.P. K. The rationale of maxillary premolar
rextraction only in Class II therapy. Am J Orthod
Dentofacial Orthop. 1963;49:276-93.
29. Gianelly AA. Distal movement of the maxillary molars.
Am J Orthod Dentofacial Orthop. 1998;114:66-72.
30. Bryk C, White LW. The geometry of Class II correction
with extractions. J Clin Orthod. 2001;35:570-9.
27
31. Gianelly AA. A strategy for nonextraction Class II
treatment. Semin Orthod. 1998;4:26-32.
32. Kaplan NL. Comparison of effects of the Distal Jet
appliance, upper premolar extraciotn and headgear in
patients with Class II malocclusion [unpublished
Masters Degree Thesis]. Saint Louis,MO: SLU, C.A.D.E.;
2011.
33. Gulati S, Kharbanda OP, Parkash H. Dental and skeletal
changes after intraoral molar distalization with
sectional jig assembly. Am J Orthod Dentofacial
Orthop. 1998;114:319-27.
34. Ottofy L. Standard Dental Dictionary. Chicago: Laird
and Lee,Inc; 1923.
35. Wahl N. Orthodontics in 3 millennia. Chapter 15:
Skeletal anchorage. Am J Orthod Dentofacial Orthop.
2008;134:707-10.
36. Roberts WE, Helm FR, Marshall KJ, Gongloff RK. Rigid
endosseous implants for orthodontic and orthopedic
anchorage. Angle Orthod. 1989;59:247-56.
37. Creekmore TD, Eklund MK. The possibility of skeletal
anchorage. J Clin Orthod. 1983;17:266-9.
38. Cope JB. Temporary anchorage devices in orthodontics:
A paradigm shift. Seminars in Orthodontics.
2005;11:3-9.
39. Escobar SA, Tellez PA, Moncada CA, Villegas CA, Latorre
CM, Oberti G. Distalization of maxillary molars with
the bone-supported pendulum: a clinical study. Am J
Orthod Dentofacial Orthop. 2007;131:545-9.
40. Gelgor IE, Buyukyilmaz T, Karaman AI, Dolanmaz D,
Kalayci A. Intraosseous screw-supported upper molar
distalization. Angle Orthod. 2004;74:838-50.
41. Kircelli BH, Pektas ZO, Kircelli C. Maxillary molar
distalization with a bone-anchored pendulum appliance.
Angle Orthod. 2006;76:650-9.
28
42. Kinzinger GS, Gulden N, Yildizhan F, Diedrich PR.
Efficiency of a skeletonized distal jet appliance
supported by miniscrew anchorage for noncompliance
maxillary molar distalization. Am J Orthod
Dentofacial Orthop. 2009;136:578-86.
43. Polat-Ozsoy O, Kircelli BH, Arman-Ozcirpici A, Pektas
ZO, Uckan S. Pendulum appliances with 2 anchorage
designs: conventional anchorage vs bone anchorage. Am
J Orthod Dentofacial Orthop. 2008;133:339.e9-.e17.
44. Fudalej P, Antoszewska J. Are orthodontic distalizers
reinforced with the temporary skeletal anchorage
devices effective? Am J Orthod Dentofacial Orthop.
2011;139:722-9.
45. Bowman SJ. Miniscrew implant molar distalization:
Evolution of the horseshoe Jet In: Papadopoulos MA,
editor. Skeletal Anchorage in Orthodontic Treatment of
Class II Malocclusion: Contemporary Applications of
Orthodontic Implants, Miniscrew Implants and Mini
Plates: Mosby Inc; 2014.
46. Baumgartner KM. Evaluation of final effects of
conventional versus implant supported distal jet
followed by comprehensive orthodontic treatment.
St.Louis,MO: Saint Louis University; 2012.
47. Cozzani M, Pasini M, Zallio F, Ritucci R, Mutinelli S,
Mazzotta L, Giuca MR, Piras V. Comparison of
maxillary molar distalization with an implantsupported distal jet and a traditional tooth-supported
distal jet appliance. Int J Dent. 2014;2014:937059.
29
CHAPTER 2: JOURNAL ARTICLE
Abstract
Purpose: The purpose of this study is to investigate the
soft tissue and dentoalveolar effects of the extraction of
the two maxillary first premolars versus distalization with
the Temporary Anchorage Device (TAD) supported Distal Jet.
Materials and Methods: A sample of 60 age-matched subjects
were selected with the following criteria: 1)Caucasians,
2)adolescents, 3) a diagnosis of at least a Class II
subdivision, 4) no missing teeth, 5) ≤5mm of initial
crowding for both upper and lower arch and, 6) good quality
pre- and post-treatment cephalometric radiographs. The
sample was divided into two groups: 31 cases that were
treated with the extraction of two maxillary first
premolars (U4s group) and 29 cases that were treated using
the TAD-supported Distal Jet (DJ group). Pre-treatment and
post-treatment cephalograms were analyzed as 4 angular and
12 linear measurements were calculated. Independent and
paired t-tests were used to detect differences in mean
changes as a result of treatment between and within the two
groups respectively. Results: At T2, the upper first molars
moved mesially (4.13±3.27mm) in the U4s group, while for
the DJ group they moved distally (1.66±2.86mm). The final
30
position of the upper incisors was more protrusive for the
DJ group with a greater U1-SN angle compared to the U4s
group by 3.21mm and 11.53° respectively. The mean change of
upper and lower lip position was not statistically
significant between the two groups. Conclusion: The results
of this study do not support choosing the extraction of two
upper first bicuspids over distalizing the maxillary molars
in the hope of achieving a different soft tissue response.
However,the upper incisors were found to be more retracted
and upright in the U4s group compared to the DJ group.
31
Introduction
A Class II Division 1 malocclusion can negatively
affect the perception of children and adolescents by their
peers and adults, as they may be considered less
attractive, less desirable as friends, less intelligent and
more likely to have an aggressive behavior1. Apart from
that, there is increased likelihood that those patients
might experience speech and swallowing difficulties2 as well
as dental trauma3. All things considered, it is not
surprising that patients with Class II Division 1
malocclusion are met daily in orthodontic practices seeking
treatment in order to improve their facial and dental
appearance.
As a result of the increased demand for orthodontic
intervention, treating Class II patients has been a
clinical challenge for many years in orthodontics, as there
are many treatment options and many appliances to choose
from. Overtime, different postulations have prevailed in
regards to the treatment of Class II cases, thus affecting
the decisions of the contemporary clinicians, which is why
the need to compare and evaluate the various treatment
modalities is so important.
32
The present study will compare the final outcome of
two treatment options used for a Class II correction:
1) Extraction of maxillary first bicuspids and 2)the
Temporary Anchorage Device (TAD) supported Distal Jet
appliance both followed by fixed orthodontic appliances.
More specifically, this study will compare the differencesif any-in the dentoalveolar and soft tissue effects of the
two treatment modalities because even though, there are a
few related studies4-8 in the literature, none of them is
directly comparing the two treatment options, at least to
the author’s knowledge.
In terms of the effect of the extraction of two upper
first bicuspids on the soft tissue and in particular the
lip retraction, there is conflicting evidence in the
literature. A study by Bokas & Colette9, which compared the
pre- and post- treatment cephalograms of 35 patients
treated with U4s extractions, found no flattening of the
profile. Similarly, another study from Janson and
coworkers10 compared the soft tissue effects of U4s
extractions versus a non-extraction group in a total of 44
patients and found that the post treatment soft tissue
effect was similar for the two groups with the exception of
33
the lower lip that was more protruded in the non-extraction
group.
However, in the 2009 study by de Almeida-Pedrin et al4,
the investigators compared the post- to pre- treatment
changes of upper first bicuspids extractions to a cervical
headgear and a tooth-borne pendulum distalizer group in a
total of 82 class II patients. According to the results,
the skeletal effects were similar for all three treatment
modalities at the end of the treatment but increased
retrusion of the upper lip was noted for the U4s extraction
group as well as increased incisors retraction compared to
the other two groups. These findings were confirmed by
Kaplan5,as in a total of 150 patients treated with either
U4s extraction, a conventional distal jet or a headgear,
the lip retraction was found to be greater for the U4s
extraction group.
In regards to the TAD-supported Distal Jet, there are
limited studies in the literature, such as the one by
Kinzinger et al11 where the pre- and post- treatment
cephalograms and dental casts of 10 patients treated with
the TAD-supported Distal Jet were analyzed and compared to
the existing literature for various conventional
distalizers. The study concluded that the TAD-supported
34
Distal Jet allowed for greater molar distalization compared
to the equivalent tooth-borne appliances, which was also
confirmed later by Cozzani and co-workers6 in a direct
comparison of 18 patients treated with a TAD-supported
Distal Jet to a control group treated with the conventional
Distal Jet.
These findings are in contrast to Baumgartner’s study7
that found similar molar distalization and tipping for both
the conventional and the TAD-supported Distal Jet in a
total of 54 patients, as well as no significant differences
in the amount of overjet correction and incisor retraction
between the two groups.
Apparently there is controversial data with little to
no mention at all of the soft tissue response in these
studies, which is why the present study will contribute to
the existing literature by directly comparing the above
mentioned treatment modalities and evaluating their
dentoalveolar as well as their soft tissue effects.
35
Material and Methods
Sample
The patients for the first group were selected from
the private office of a single clinician and consisted of
29 patients treated with the TAD-supported Horseshoe Distal
Jet (DJ group), which is illustrated in Figure 2.1.
Contingent on the sample distribution and characteristics
of the first group, 31 cases treated with two maxillary
first premolar extractions were selected from the archiving
records at Saint Louis University Center for Advanced
Dental Education (U4s group).
Eventually, the data for this retrospective clinical
study were gathered from a total of 60 patients and the
following inclusion criteria were established:
1.Caucasians, 2.adolescents, 3.a previous diagnosis of at
least Class II subdivision, 4.no congenitally missing
teeth, 5.≤5mm of initial crowding for both the upper and
the lower arch and, 6.diagnostic quality pre (T1) and post
(T2) treatment lateral cephalograms for each subject. The
two groups were matched as closely as possible in terms of
pre-treatment age, overjet (OJ) and ANB values, as shown in
Table 2.1.
36
Table 2.1: Age/sex, initial overjet (OJ), ANB distribution
of the study groups and treatment (Tx) duration
Group
Subjects
T1-Mean age
(Range)
T1-Mean OJ
(Range)
T1-Mean ANB
(Range)
Tx duration
TAD-supported
Distal Jet
N=29
F=15
M=14
13y2m ± 14m
(10y9m - 16y5m)
3.7mm ± 1.3mm
(1.8 - 6.3mm)
3.8° ± 1.8°
(1° - 7.5°)
956 days
U4s extractions
N=31
F=16
M=15
13y1m ± 20m
(9y6m - 16y6m)
5.2mm ± 1.5mm
(2.7 - 9mm)
5.2° ± 1.7°
(1.5° - 8°)
963 days
In the first group, once a Class I molar relationship
was achieved with the distalization , a conventional
orthodontic treatment followed, with retraction mechanics
for the maxillary anterior teeth where the TAD-supported
Horseshoe Distal Jet was used as a TAD-supported anchorage
system. Class II elastics were used when indicated.
For the second group, after the extraction of the
maxillary first bicuspids, reciprocal closure of the
extraction space was followed by the retraction of the
anterior teeth, supported by Class II elastics when needed.
37
Figure 2.1: TAD-supported Horseshoe Distal Jet ( photo
courtesy of Dr. S. Jay Bowman12)
Methodology
Pre-treatment crowding was determined by visual
analysis of the dental casts but in cases with mixed
dentition or questionable amount of crowding, the TanakaJohnston formula or the Tooth Size Arch Length Discrepancy
analysis was used respectively, in order to include or
exclude the case in question.
For each of the patients, pre-treatment (T1) and posttreatment (T2) cephalograms were hand traced on acetate
paper by a single investigator and 11 hard and soft tissue
38
anatomical landmarks were located. Their definition can be
seen in Table 1 of the Appendix and a diagram of their
location is illustrated in Figure 2.2.
Figure 2.2: Anatomical landmarks and reference planes.
For the cephalometric measurements, two reference
planes were constructed and used as an x-y coordinate grid.
A horizontal line was created parallel to the sella-nasion
line minus seven degrees (SN-7°), and a vertical line was
created perpendicular to SN-7° passing through sella
(Figure 2.1).
39
From the landmarks and reference planes, 4 angular
(ANB,SN-MP,U1-SN,IMPA),6 linear horizontal and 6 linear
vertical measurements were derived and processed as shown
in Figures 2.3 and 2.4 respectively. For the mandibular
plane (MP), a line starting from Me (Menton) and tangent to
the posterior border of the mandible was constructed and
used for the IMPA and the SN-MP angles.
Figure 2.3 Horizontal linear measurements
40
Figure 2.4 Vertical linear measurements
To correct for magnification differences between
cephalograms, all linear measurements were converted to
indices of the sella-nasion distance.
The indices were
calculated by multiplying the linear measurements of each
subject by the individually calculated sella-nasion
distance ratio from the T1 and T2 cephalograms of that same
subject.
41
Statistical Analysis
Descriptive data was obtained for all measurements and
statistical analysis was done utilizing the Statistical
Package for the Social Science (IBM SPSS, Version 20,
Armonk, NY). Paired t-tests were used for each variable to
evaluate differences between pre-treatment and posttreatment measurements within each group. Independent
sample t-tests were used for each variable to detect
differences in mean changes between the Distal Jet group
and the upper first premolar extraction groups.
A
significance level of p <.05 was set to detect differences
for all statistical analyses.
Reliability
Cronbach’s alpha was used to determine consistency of the
measurements.
Reliability is considered to be “adequate”
when intra-class correlations were greater than or equal to
0.80.
10% of both samples (3 patients from each group)
were randomly selected and re-measured to test for intraexaminer reliability. Cronbach’s alpha was calculated as
94% for all variables measured, thus indicating that the
measured and repeated measurements were at an acceptable
level of reliability for accuracy of measurements.
42
Results
Pre-Treatment Measurements
Independent sample t-tests were calculated for each
variable to detect differences at the start of treatment
between the premolar extraction and the Distal Jet group.
The results showed a bigger initial ANB, IMPA and U1-SN
angle as well as increased initial overjet by 1.49mm for
the U4s group, which were all considered to be
statistically significant.
Furthermore, there were other statistically
significant differences at T1 between the two groups,
regarding the upper incisor position, that seemed to be
more anteriorly displaced (66.85mm ±4.67mm) and relatively
intruded (65.73mm ±5.22mm) in the U4s versus the U1Horizontal (64.26mm ±4.91mm)- t(58)=2.093,p=0.05U1-Vertical (68.06mm ±3.43mm)-t(58)=.142,p=0.05measurements of the DJ group.
43
and the
Table 2.2 Pre-treatment measurements for both groups
Pre-treatment Measurements
U4s
Group
DJ
Variables
Mean
SD
Mean
SD
ANB(°)
5.18
1.78
3.78
1.83
0.004*
SN-MP(°)
32.98
5.05
31.78
5.43
0.381
IMPA(°)
98.35
5.88
90.50
6.38
0.000*
U1-SN(°)
101.75
7.57
93.29
7.03
0.000*
(OJ) Overjet(mm)
5.18
3.69
3.69
1.3
0.000*
Ls-Horizontal(mm)
79.84
4.53
78.91
6.28
0.510
Li-Horizontal(mm)
74.96
4.56
74.92
5.84
0.974
U1-Horizontal(mm)
66.85
4.67
64.26
4.91
0.041*
L1-Horizontal(mm)
61.61
4.5
60.59
4.64
0.390
U6-Horizontal(mm)
39.92
4.23
39.55
4.64
0.750
L6-Horizontal(mm)
37.58
4.57
37.18
4.8
0.740
Ls-Vertical(mm)
57.57
4.69
59.21
3.58
0.131
Li-Vertical(mm)
70.21
5.93
70.03
3.89
0.888
U1-Vertical(mm)
65.73
5.27
68.06
3.43
0.049*
L1-Vertical(mm)
62.03
5.28
63.05
3.81
0.398
U6-Vertical(mm)
58.57
4.29
59.97
3.33
0.165
L6-Vertical(mm)
62.46
4.35
64.21
3.23
0.084
*P<.05
44
Sig.
Treatment Changes
Descriptive data was obtained for the pre- and posttreatment changes within each group and paired t-tests were
used for all the variables. For the extraction group, the
post-treatment SN-MP and U1-SN angle as well as the
horizontal linear position of both the upper and the lower
lip, seemed to be unaffected. In contrast, all the other
variables showed statistically significant changes from
pre- to post-treatment values.
For the TAD-supported Distal Jet group, the variables
that remained unaffected from T1 to T2 were the SN-MP angle
and the horizontal position of both lips and the upper
incisors as well. All other variables showed statistically
significant changes due to the treatment, including the
U1-SN angle even though -for the U4s group-it was not
affected.
Details are given below in Tables 2.3 and 2.4,
while the descriptive data for all variables at T1 and T2
in both groups can be found in Table A.2 and Table A.3 of
the Appendix.
45
Table 2.3 Treatment changes for U4s extraction group
T2-T1 Changes
Variables
Mean change
SD
Sig.
-1.49
2.23
.001*
SN-MP(°)
.03
2.26
.937
IMPA(°)
3.23
5.66
.003*
U1-SN(°)
-2.63
8.01
.077
Ls-Horizontal(mm)
.31
3.62
.633
Li-Horizontal(mm)
.87
3.39
.166
U1-Horizontal(mm)
-1.75
3.45
.008*
L1-Horizontal(mm)
1.38
2.60
.006*
U6-Horizontal(mm)
4.13
3.27
.000*
L6-Horizontal(mm)
2.17
3.46
.002*
Ls-Vertical(mm)
2.51
2.53
.000*
Li-Vertical(mm)
2.61
3.95
.001*
U1-Vertical(mm)
1.60
2.26
.000*
L1-Vertical(mm)
4.17
3.16
.000*
U6-Vertical(mm)
3.01
2.55
.000*
L6-Vertical(mm)
2.80
2.92
.000*
ANB(°)
*P˂.05
46
Table 2.4 Treatment changes for the Distal Jet group
T2-T1 Changes
Variables
Mean change
SD
Sig.
ANB(°)
-.92
1.51
.003*
SN-MP(°)
.91
2.59
.068
IMPA(°)
6.17
6.98
.000*
U1-SN(°)
8.90
9.23
.000*
Ls-Horizontal(mm)
.19
3.90
.799
Li-Horizontal(mm)
1.27
4.20
.114
U1-Horizontal(mm)
1.46
4.09
.065
L1-Horizontal(mm)
2.69
3.53
.000*
U6-Horizontal(mm)
-1.66
2.86
.004*
L6-Horizontal(mm)
2.51
3.37
.000*
Ls-Vertical(mm)
1.88
2.36
.000*
Li-Vertical(mm)
2.27
2.66
.000*
U1-Vertical(mm)
2.03
2.63
.000*
L1-Vertical(mm)
5.26
2.69
.000*
U6-Vertical(mm)
1.87
2.00
.000*
L6-Vertical(mm)
2.61
2.39
.000*
*P˂.05
47
Independent sample t-tests were calculated for each
variable to detect differences in mean treatment changes
between the premolar extraction group and the Distal Jet
group (Table 2.5). The results show that the group with
the premolar extractions showed a statistically
significant decrease in the U1-SN angle (-2.63°±8.01°)
from T1 to T2 compared to the Distal Jet group where in
fact the U1-SN angle increased from T1 to
T2(8.90°±9.23),t(58)=-5.175,p=0.05.
There was also a significant effect of the two
different treatment modalities on the horizontal
displacement of the upper incisors (U1-Horizontal),
t(58)=-3.295,p=0.05. In fact, in the extraction group
the final position of the upper incisors was retruded
compared to their initial pre-treatment position (mean
treatment change:-1.75±3.45mm) in contrast to the distal
jet group where the incisors were anteriorly displaced
at T2 (mean treatment change: 1.46±4.09mm).
Another statistically significant difference
between the treatment effects of the two groups, was the
antero-posterior displacement of the upper first molars
(U6-Horizontal), t(58)=7.281, p=0.05. In the U4s group
the maxillary first molars moved mesially at the end of
48
the treatment (4.13±3.27mm) while in the Distal Jet
group they moved distally (-1.66±2.86mm).
49
Table 2.5 Treatment changes between U4s and DJ group
T2 to T1 Changes
U4s Group
T2-T1
Distal Jet
Group
T2-T1
Mean
SD
Change
Variables
Mean
Change
SD
ANB(°)
-1.48
2.23
-.91
SN-MP(°)
.03
2.26
IMPA(°)
3.23
U1-SN(°)
U4s-DJ
Differences
Mean
Sig.
1.52
-.57
.256
-.88
.165
5.66
.91
2.59
T1-T2
6.17
6.98
-2.94
.077
-2.63
8.01
8.90
9.23
-11.53
.000*
Ls-Horizontal(mm)
.31
3.62
.19
3.90
.12
.896
Li-Horizontal(mm)
.87
3.39
1.27
4.20
-.40
.680
U1-Horizontal(mm)
-1.75
3.45
1.46
4.09
-3.21
.002*
L1-Horizontal(mm)
1.39
2.60
2.68
3.53
-1.29
.109
U6-Horizontal(mm)
4.13
3.27
-1.66
2.86
5.79
.000*
L6-Horizontal(mm)
2.17
3.46
2.51
3.37
-.34
.697
Ls-Vertical(mm)
2.52
2.53
1.88
2.36
.64
.316
Li-Vertical(mm)
2.60
3.95
2.27
2.66
.33
.700
U1-Vertical(mm)
1.61
2.26
2.03
2.63
-.42
.501
L1-Vertical(mm)
4.17
3.16
5.26
2.69
-1.09
.157
U6-Vertical(mm)
3.01
2.55
1.86
2.00
1.15
.059
L6-Vertical(mm)
2.80
2.92
2.61
2.39
.19
.780
*P˂0.05
50
Discussion
There are limited previous studies in the literature
comparing the treatment effects of the maxillary first
bicuspid extractions to various distalizing methods4,
5, 8
with only a few of them including the tooth supported
Distal Jet- and even fewer studies comparing the
conventional to the TAD-supported Distal Jet with little or
no focus on the soft tissue reaction6, 7. However, to the
best of the author’s knowledge, there is no study in the
literature directly comparing the treatment effects of the
upper bicuspid extractions group to the TAD-supported
Distal Jet.
Another way that this study is different to the
others and contributes to the existing literature is in the
sample selection and methodology. Both groups included,
were age matched and even though eliminating the growth
factor from the equation -regarding its contribution to the
treatment changes and especially the soft tissue- is
practically impossible, it could be considered equal for
both groups. Apart from that, the study focused on patients
with the same ethnical background -Caucasians- to eliminate
any ethnic differences related to soft and hard tissue
characteristics and morphology13 and also both groups had
51
about the same amount of initial crowding. This is
important in determining the final lip position, as there
are some studies in the literature indicating a correlation
between incisor retraction and post-treatment lip
position14-16. Consequently, if the space created by either
molar distalization or two premolar extractions was
randomly used for both crowding alleviation and incisor
retraction -without eliminating one of the two variablesit would affect the findings of the study. Finally, using
the upper and lower lip horizontal distance from a stable
reference plane instead of other profile planes, increases
the validity of the study in evaluating the lip position17.
Limitations
It would be a preterition to interpret the results of
the present study and compare them to the findings of
similar existing publications, without acknowledging its
limitations first. It should be mentioned that even though
the subjects in the Distal Jet group were treated by the
same clinician, that is not the case in the extraction
group where the patients were treated by numerous
clinicians over a span of 3 decades.
Another limitation of the present study is the small
sample size that decreases the power of the results as in
52
all studies where linear measurements -that have a bigger
envelope of error- are included in the methodology. As a
result of the small sample size, the present study did not
differentiate between genders, so both males and females
were included in the sample without taking into account
gender related differences in soft tissue.
Finally, lip morphology- especially lip strain and
thickness-that also has an effect in the variability of lip
retraction as mentioned in the literatute18-20, has not been
taken into account in the present study.
Results compared to the literature
Due to the lack of identical studies in the existing
literature, the findings of the present study will be
compared to older ones that were following different
protocols.
Pre-treatment measurements of both groups were
compared and it was found that the two first premolar
extraction group had an increased initial ANB angle by 1.4°
compared to the corresponding angle in the Distal Jet group
and also an increased initial overjet by 1.49 mm compared
to the Distal Jet group, both of which values were of
statistically significant difference. Apart from that, the
Distal Jet group appeared to have less proclined upper and
53
lower incisors before the beginning of the treatment compared to
the other group.
According to the results of the present study, the main
differences between the two groups from T1 to T2 were evident in
the horizontal position of the upper first molars and the upper
incisors. In fact these results are consistent with Kaplan’s
findings5 who also found a more mesial final position of the
upper first molars for the U4s extraction group by 4.8mm
compared to 4.13mm of mesial movement found in the present
study, as expected due the movement of the upper first
molars into the upper premolar extraction site.
However, the present study found a distal movement (a
mean of 1.66 mm) of the upper first molars of the TADsupported Distal Jet as well, in contrast to Kaplan’s
findings where the Distal Jet group showed a net mesial
movement of the upper molars of 0.3mm. The difference in
these findings can easily be explained by the fact that in
Kaplan’s study, a conventional Distal Jet was used so it
could be assumed that during the incisor retraction phase
of the treatment, most of the distalization of the upper
molars was lost as a result of loss of anchorage.
The amount of molar distalization in the TAD-supported
Distal Jet group found in this study is smaller than the
amount of distalization found in other studies evaluating
54
the effect of other types of TAD-supported distalizers,
such as the Gelgor et al study21 that showed a mean of 3.9mm
of molar distalization, when using a TAD-supported TPA and
NiTi coils. Other studies in which the amount of distal
molar movement was greater, was the one conducted by
Escobar et al22-showing a mean of 6mm of molar distalization
- or the study by Polat-Ozsoy23according to which the mean
distalization was 4.8mm for the upper molars, when a TADsupported Pendulum was used for the test group. The
discrepancy between the amount of distalization found in
this study and the ones mentioned above could be attributed
to the fact that different measurements and TAD-supported
appliances were used. Besides that, the amount of
distalization found in the previous studies was measured
immediately post-distalization, while in the present study
the results reflect the amount of movement after
comprehensive treatment, a fact that might also explain the
numeric differences.
Another finding resulting from the present study was
the increased retraction (-1.75±3.45mm) of the upper
incisors which was noticed for the U4s group compared to
the DJ group where in fact the upper incisor tip seemed to
moved forward (1.46±4.09mm). This is in accordance with
55
Kaplan’s findings where the incisor retraction for the
extraction group was -1.3±1.8mm compared to 0.5±2.1mm for
the conventional Distal Jet group. These results also agree
with Stalpers et al24, who measured a mean incisor
retraction of -2.72±1.88mm at T2 as a result of the
extraction of two upper first premolars. The greater amount
of incisor retraction in the Stalpers study, could be
explained by the fact that the initial mean overjet was
greater (7.328±1.84mmmm) compared to the present study
(5.18±3.69mm) for the U4s group which implies the necessity
for different anchorage considerations.
In terms of the U1-SN angle, the present study’s
results found that in the U4s group the upper incisors were
more retroclined from T2-T1 (U1-SN:-2.63° ± 8°) compared to
the DJ group which is different from Kaplan’s study, where
in fact no statistically significant difference was noted
between the extraction and the conventional Distal Jet
group. This is also what Almeida-Pedrin at al4 found in
their comparison of the effects of U4s extraction to the
conventional pendulum appliance. A plausible explanation
for the conflicting results about the U1-SN angle between
the present study and the existing ones, could be the fact
that different appliances and protocols were used, as well
56
as the fact that the patients in the U4s group of the
present study were treated by multiple clinicians, hence it
would be safe to assume that different and inconsistent
torque control skills and techniques were applied to each
case.
In terms of the amount of lip retraction, the present
study found no significant difference between the two
groups. These findings are in contrast to the two above
mentioned studies by Kaplan and Almeida-Pedrin et al, who
both found less retrusion of the upper lip to the E-plane
for the group with the conventional distalizing appliance.
This could be explained by the fact that in both studies at
T1, the upper incisors were proclined more in the
distalizing group and with the existing evidence in the
literature connecting the upper incisor inclination with
the lip position24,
25
, the assumption is evident. Besides
that, both of those studies used the E plane as a reference
in order to evaluate the final lip position, thus allowing
for growth effects to influence the measurements given the
augmentation of the chin and the elongation of the nose.
57
Conclusions
1. Choosing to use a TAD-supported Distal Jet instead of
extracting two first maxillary premolars in the hope
of achieving a different soft tissue response is not
supported by the results of this study.
2. More upper incisor retraction can be expected when two
first maxillary premolars are extracted compared to
using a TAD-supported Distal Jet for a Class II
Division 1 correction.
3. More upright upper incisors are a result of the
extraction of the two upper premolars while no such
effect was noticed in the TAD-supported Distal Jet
treatment.
58
References
1. Shaw WC. The influence of children's dentofacial
appearance on their social attractiveness as judged by
peers and lay adults. Am J Orthod. 1981;79:399-415.
2. Rothstein T, Yoon-Tarlie C. Dental and facial skeletal
characteristics and growth of males and females with
class II, division 1 malocclusion between the ages of
10 and 14 (revisited)-part I: characteristics of size,
form, and position. Am J Orthod Dentofacial Orthop.
2000;117:320-32.
3. Hunter ML, Hunter B, Kingdon A, Addy M, Dummer PM, Shaw
WC. Traumatic injury to maxillary incisor teeth in a
group of South Wales school children. Endod Dent
Traumatol. 1990;6:260-4.
4. de Almeida-Pedrin RR, Henriques JF, de Almeida RR, de
Almeida MR, McNamara JA, Jr. Effects of the pendulum
appliance, cervical headgear, and 2 premolar
extractions followed by fixed appliances in patients
with Class II malocclusion. Am J Orthod Dentofacial
Orthop. 2009;136:833-42.
5. Kaplan NL. Comparison of effects of the Distal Jet
appliance, upper premolar extraciotn and headgear in
patients with Class II malocclusion [unpublished
Masters Degree Thesis]. Saint Louis,MO: SLU, C.A.D.E.;
2011.
6. Cozzani M, Pasini M, Zallio F, Ritucci R, Mutinelli S,
Mazzotta L, Giuca MR, Piras V. Comparison of
maxillary molar distalization with an implantsupported distal jet and a traditional tooth-supported
distal jet appliance. Int J Dent. 2014;2014:937059.
7. Baumgartner KM. Evaluation of final effects of
conventional versus implant supported distal jet
followed by comprehensive orthodontic treatment.
St.Louis,MO: Saint Louis University; 2012.
8. Pinzan-Vercelino CR, Janson G, Pinzan A, de Almeida RR,
de Freitas MR, de Freitas KM. Comparative efficiency
of Class II malocclusion treatment with the pendulum
appliance or two maxillary premolar extractions and
edgewise appliances [corrected]. Eur J Orthod.
2009;31:333-40.
59
9. Bokas J, Collett T. Effect of upper premolar
extractions on the position of the upper lip.
Orthod J. 2006;22:31-7.
Aust
10. Janson G, Fuziy A, de Freitas MR, Castanha Henriques
JF, de Almeida RR. Soft-tissue treatment changes in
Class II Division 1 malocclusion with and without
extraction of maxillary premolars. Am J Orthod
Dentofacial Orthop. 2007;132:729.e1-8.
11. Kinzinger GS, Gulden N, Yildizhan F, Diedrich PR.
Efficiency of a skeletonized distal jet appliance
supported by miniscrew anchorage for noncompliance
maxillary molar distalization. Am J Orthod
Dentofacial Orthop. 2009;136:578-86.
12. Bowman SJ. Miniscrew implant molar distalization:
Evolution of the horseshoe Jet In: Papadopoulos MA,
editor. Skeletal Anchorage in Orthodontic Treatment of
Class II Malocclusion: Contemporary Applications of
Orthodontic Implants, Miniscrew Implants and Mini
Plates: Mosby Inc; 2014.
13. Brock RA, 2nd, Taylor RW, Buschang PH, Behrents RG.
Ethnic differences in upper lip response to incisor
retraction. Am J Orthod Dentofacial Orthop.
2005;127:683-91; quiz 755.
14. Waldman BH. Change in lip contour with maxillary
incisor retraction. Angle Orthod. 1982;52:129-34.
15. Garner LD. Soft-tissue changes concurrent with
orthodontic tooth movement. Am J Orthod.
1974;66:367-77.
16. Kasai K. Soft tissue adaptability to hard tissues in
facial profiles. Am J Orthod Dentofacial Orthop.
1998;113:674-84.
17. Buschang PH, Fretty K, Campbell PM. Can commonly used
profile planes be used to evaluate changes in lower
lip position? Angle Orthod. 2011;81:557-63.
18. Oliver BM. The influence of lip thickness and strain
on upper lip response to incisor retraction. Am J
Orthod. 1982;82:141-9.
60
19. Burstone CJ. Lip posture and its significance in
treatment planning. Am J Orthod. 1967;53:262-84.
20. Talass MF, Talass L, Baker RC. Soft-tissue profile
changes resulting from retraction of maxillary
incisors. Am J Orthod Dentofacial Orthop.
1987;91:385-94.
21. Gelgor IE, Buyukyilmaz T, Karaman AI, Dolanmaz D,
Kalayci A. Intraosseous screw-supported upper molar
distalization. Angle Orthod. 2004;74:838-50.
22. Escobar SA, Tellez PA, Moncada CA, Villegas CA, Latorre
CM, Oberti G. Distalization of maxillary molars with
the bone-supported pendulum: a clinical study. Am J
Orthod Dentofacial Orthop. 2007;131:545-9.
23. Polat-Ozsoy O, Kircelli BH, Arman-Ozcirpici A, Pektas
ZO, Uckan S. Pendulum appliances with 2 anchorage
designs: conventional anchorage vs bone anchorage. Am
J Orthod Dentofacial Orthop. 2008;133:339.e9-.e17.
24. Stalpers MJ, Booij JW, Bronkhorst EM, Kuijpers-Jagtman
AM, Katsaros C. Extraction of maxillary first
permanent molars in patients with Class II Division 1
malocclusion. Am J Orthod Dentofacial Orthop.
2007;132:316-23.
25. Scott Conley R, Jernigan C. Soft tissue changes after
upper premolar extraction in Class II camouflage
therapy. Angle Orthod. 2006;76:59-65.
61
Appendix
Table A.1 Landmarks and Definitions
Landmarks
Definitions
S (Sella)
The center of the
pituitary fossa
N (Nasion)
The most anterior point of
the frontonasal suture
The most inferior midline
point on the symphyseal
outline of the mandible
Me (Menton)
A (A point)
B (B point)
Ls (Labrale superioris)
Li (Labrale inferioris)
The most posterior point
of the maxilla in the
concavity between the
anterior nasal spine and
prosthion
The most posterior point
of the mandible in the
concavity between
infradentale and pogonion
The most prominent point
on the upper lip
The most prominent point
of the lower lip
U1 (Maxillary Incisor Tip)
The incisal tip of the
maxillary central incisor
L1(Mandibular Incisor Tip)
The incisal tip of the
mandibular central incisor
U6 (Upper molar)
The mesial contact point
of the maxillary first
molar
The mesial contact point
of the mandibular first
molar
L6 (lower molar)
62
Table A.2 Descriptive statistics for U4s group
T1
T2
Variables
Mean
SD
Mean
SD
ANB(°)
5.18
1.78
3.69
2.10
SN-MP(°)
32.97
5.05
33.00
5.64
IMPA(°)
98.35
5.88
101.58
5.87
U1-SN(°)
101.74
7.57
99.11
6.28
Ls-Horizontal(mm)
79.84
4.53
80.15
5.99
Li-Horizontal(mm)
74.96
4.56
75.83
5.82
U1-Horizontal(mm)
66.85
4.67
65.10
5.22
L1-Horizontal(mm)
61.61
4.50
62.99
5.04
U6-Horizontal(mm)
39.92
4.23
44.05
5.27
L6-Horizontal(mm)
37.58
4.57
39.75
4.96
Ls-Vertical(mm)
57.56
4.69
60.07
4.63
Li-Vertical(mm)
70.21
5.93
72.82
5.53
U1-Vertical(mm)
65.73
5.27
67.33
4.76
L1-Vertical(mm)
62.03
5.28
66.20
4.63
U6-Vertical(mm)
58.57
4.29
61.58
4.02
L6-Vertical(mm)
62.46
4.35
65.26
3.93
63
Table A.3 Descriptive statistics for the DJ group
T1
Variables
ANB(°)
Mean
3.78
T2
SD
Mean
SD
1.83
2.86
2.27
SN-MP(°)
31.78
5.43
32.69
6.32
IMPA(°)
90.5
6.38
96.67
5.59
U1-SN(°)
93.29
7.04
102.19
5.85
78.9
6.28
79.09
6.76
74.92
5.84
76.19
6.26
U1-Horizontal(mm)
64.26
4.91
65.72
5.62
L1-Horizontal(mm)
60.59
4.64
63.28
5.39
U6-Horizontal(mm)
39.55
4.64
37.89
4.80
L6-Horizontal(mm)
37.18
4.80
39.69
5.08
59.21
3.58
61.09
4.68
70.03
3.89
72.30
4.61
68.06
3.43
70.09
4.00
L1-Vertical(mm)
63.05
3.81
68.31
4.02
U6-Vertical(mm)
59.97
3.33
61.84
3.48
L6-Vertical(mm)
64.21
3.23
66.82
3.71
Ls-Horizontal(mm)
Li-Horizontal(mm)
Ls-Vertical(mm)
Li-Vertical(mm)
U1-Vertical(mm)
64
Vita Auctoris
Evmorfia Fotakidou was born on August 24th, 1984 in
Serres, Greece to Iordanis Fotakidis and Evaggelia
Polyzoidou.
She graduated from the 3rd High School of Serres in
2002.
After high school, she started dental school at the
Aristotle University while at the same time she received
her training at the Corps Officers Military School in
Thessaloniki. In 2008, she graduated with a Doctor of
Dental Medicine degree as a second lieutenant in the Greek
Army.
In June 2012, she began the 36-month orthodontic
residency program in Saint Louis University.
She expects
to receive her Master of Science in Dentistry degree in
July 2015.
65