LONGITUDINAL GROWTH EVALUATION OF UNTREATED
SUBJECTS WITH CLASS II, DIVISION 2 MALOCCLUSION
Luiz Alexandre G. Barbosa, D.D.S.
An Abstract Presented to the Graduate Faculty of
Saint Louis University in Partial Fulfillment
of the Requirements for the Degree of
Master of Science in Dentistry (Research)
2012
Abstract
Objective: To more fully characterize the growth of
untreated Class II, Division 2 malocclusion subjects 6-19
years of age. Materials and Methods: Mixed-longitudinal
cephalograms of 39 Caucasian Class II, Division 2 subjects
were analyzed at five time points: T1 (6-7ys), T2 (9-10ys),
T3 (12-13ys), T4 (15-16ys) and T5 (18-19ys). They were
compared to an age and sex matched sample of normal Class I
controls. A total of 17 variables (12 angular and 5
proportional) were evaluated using Dolphin Imaging
software. Multilevel modeling procedures were used to
statistically evaluate the growth changes that occurred and
to determine group differences. Results: Multilevel
statistical models showed significant group differences for
seven of the 17 variables. Class II, Division 2 subjects
(12-13 years of age) demonstrated significantly (p<0.05)
smaller mandibular plane angles, smaller palatal plane to
mandibular plane angles, smaller cranial base angles (Ba-SN) and smaller U1SN angles than Class I‟s. They also had
significantly larger U1L1 angles and greater posterior to
anterior facial heights (PAFHp). The gonial angles of Class
II, Division 2 subjects were significantly smaller than the
gonial angles of Class I‟s at the 18-19 years of age.
Significant growth differences were also demonstrated, with
1
Class II, Division 2 subjects showing greater decreases of
the mandibular and palatal plane angles, greater increases
of the PAFH ratio, and smaller changes of U1-SN angle.
Conclusions: Compared to the Class I‟s, Class II, Division
2 subjects have smaller cranial base angles, more
horizontal growth patterns and more upright incisors. Most
of the differences are evident at the early ages and
increase over time.
2
LONGITUDINAL GROWTH EVALUATION OF UNTREATED
SUBJECTS WITH CLASS II, DIVISION 2 MALOCCLUSION
Luiz Alexandre G. Barbosa, D.D.S.
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 (Research)
2012
COMMITTEE IN CHARGE OF CANDIDANCY:
Adjunct Professor Peter H. Buschang,
Chairperson and Advisor
Professor Rolf G. Behrents
Professor Eustaquio Araujo
i
DEDICATION
I dedicate this thesis to my always supportive and
loving family.
To my wife, Liliane, for her love, courage and
selflessness to come to a foreign country, where she
couldn‟t speak the language at first, to support me and
take care of our family, leaving behind her own career as a
dentist in Brazil; for making my dreams, our dreams.
Without her, the completion of this educational journey
would not be a reality.
To my daughters, Isabela and Giovana, who have brought
so much joy and unconditional love to my life.
To my parents, Jose Luiz and Maria Ruth, who are
always there for me, and whose love, support and guidance
have shaped me into the person I am today.
ii
ACKNOWLEDGEMENTS
My gratitude is first to God, my Father, for life and
for all the blessings and opportunities He has given to me.
I want to thank my wife, for all her support,
especially for taking care of our kids when I needed to be
“away” in our basement to read and write.
I also want to thank my classmates. In particular, Dr.
Orn Laowansiri and Dr. Hiroshi Ueno, for their patience and
their time spent helping me to understand the statistics
and with the charts and tables, but most importantly, for
being good friends and laughing with me.
Thank you to Dr. Hans, for allowing me to collect the
data from the Bolton-Brush Growth Study (Cleveland, OH).
Lastly, a great thanks to each member of my committee
for their help, guidance and knowledge. Thanks to Dr.
Behrents for coming with me to Cleveland, OH, for helping
with the tracings and data collection and for “pushing” me
to move forward when it was necessary. Thanks to Dr.
Araujo, for being more than a professor to me, but a model
and a friend that I can always count on. A special thanks
to Dr. Buschang, for all his assistance in the project
design, statistics, for providing the sample from Montreal
and for his expertise and patience. Without his support,
none of this would have been possible.
iii
TABLE OF CONTENTS
List of Tables.............................................v
List of Figures...........................................vi
CHAPTER 1 : INTRODUCTION...................................1
CHAPTER 2 : REVIEW OF THE LITERATURE
Normal Occlusion.................................3
Definition..................................3
Prevalence of Normal Occlusion..............5
Class II, Division 2 Malocclusion................8
Definition..................................8
Etiology...................................10
Prevalence.................................14
Morphologic Characteristics................14
Cross Sectional Versus Longitudinal Studies.....21
Dentofacial Development of Untreated Normals....22
References......................................25
CHAPTER 3 : JOURNAL ARTICLE
Abstract........................................29
Introduction....................................31
Materials and Methods...........................33
Sample.....................................33
Methodology................................36
Statistical Analyses.......................40
Results.........................................41
Group Descriptive Statistics...............41
Group Comparisons..........................44
Growth Curve Showing Significant Differences....46
Growth Curve Showing No Group Differences.......50
Discussion......................................54
Conclusions.....................................61
References......................................63
Appendix..................................................67
Vita Auctoris.............................................69
iv
LIST OF TABLES
Table 2.1 - Comparative cephalometric studies describing
Class II, Division 2 characteristics .........20
Table 3.1 - Age and gender distribution of study sample...35
Table 3.2 - Definitions and abbrev. of the landmarks......37
Table 3.3 – Class I – Descriptive statistics..............42
Table 3.4 - Class II, Div. 2 – Descriptive statistics.....43
Table 3.5 – Multilevel models.............................45
Table A.1 - Class I – Descriptive changes over time.......67
Table A.2 - Class II, Div. 2 – Descriptive changes over
time .........................................68
v
LIST OF FIGURES
Figure 2.1
– Dental appearance of Class II, Div. 2......9
Figure 3.1
– Anatomical landmarks......................38
Figure 3.2
– Cephalometric measurements................39
Figure 3.3
– Variables showing significant differences
between Cl I and Cl II, Division 2
subjects .................................47
Figure 3.4
– Variables showing significant differences
between Cl I and Cl II, Division 2
subjects..................................49
Figure 3.5
– Variables showing non-significant
differences between Cl I and Cl II,
Division 2 subjects ......................51
Figure 3.6
– Variables showing non-significant
differences between Cl I and Cl II,
Division 2 subjects ......................52
Figure 3.7
– Variables showing non-significant
differences between Cl I and Cl II,
Division 2 subjects ......................53
vi
CHAPTER 1: INTRODUCTION
Description of the Problem
Class II, Division 2 malocclusion is not very common
among the population, with prevalence ranging between 2.3%
and 5%, and it is known to be more common in Caucasians
than in any other ethnic group.1-4 It is thought to be due
to a deficiency in vertical growth5-10 and sagittal
disharmony,6-8,10-14 but not much is known about how it
develops.
A reasonable number of studies have attempted to
analyze and characterize Class II, Division 2 malocclusion,
but much controversy still exists as to its
characteristics. Several researchers have characterized the
malocclusion as an orthognathic skeleton, emphasizing that
it is mostly dentoalveolar6,9,11,14,15 Others have
characterized Class II, Division 2 malocclusion based on
unique combinations of skeletal and dentoalveolar
problems.8,10,16-18 These studies have different sample sizes
and also employed different analysis. Initially, these
studies were just based on observation of the facial and
dental characteristics, but after the invention of the
cephalostat, most of the studies used cephalograms to
measure and compare the differences between the
1
individuals.
Importantly, most of the studies have been
cross-sectional in design, probably due to the difficulty
in finding a good longitudinal untreated sample of Class
II, Division 2 subjects.
In characterizing a malocclusion and assessing growth,
the employment of longitudinal research designs is the
ideal method of study. Skeletal and facial changes can best
be appreciated by analyzing different time points during
the development of the same individuals. To date, no study
has evaluated the growth of untreated Class II, Division 2
subjects longitudinally. Longitudinal evaluation of these
subjects should provide important information concerning
the development of this type of malocclusion. In order to
fully appreciate the problem, those with the malocclusion
should be compared to others with untreated Class I normal
occlusion, who are matched by age and gender.
Based on the foregoing, the purpose of the present
study was to evaluate growth of untreated Class II,
Division 2 subjects longitudinally (6-19 years). In order
to characterize the malocclusion, the subjects will be
compared to untreated Class I normal occlusion subjects,
matched by age and gender.
2
CHAPTER 2 - REVIEW OF THE LITERATURE
Normal Occlusion
Definition
When E. H. Angle first described normal occlusion in
the late 1890‟s, it was the first time that anyone put into
words what this actually means. According to Angle, “the
upper first molars were the key to occlusion and that the
upper and lower molars should have a relationship in which
the mesiobuccal cusp of the upper molars occluded with the
buccal groove of the lower molar.” In addition, the teeth
needed to exhibit a relationship in which they were aligned
in a smooth curving line of occlusion.19 This description,
although simplified, has proved to be correct for more than
100 years.
Profitt states that the development of Angle‟s
classification of malocclusion was an important step in the
development of orthodontics because it not only subdivided
major types of malocclusion but also included the first
clear and simple definition of normal occlusion for the
natural dentition.20 Angle‟s classification system was based
on the relationship of the first molars and the alignment
(or lack thereof) of the teeth relative to the line of
occlusion. Adding to this definition of normal occlusion,
3
Angle divided malocclusions into the following well known
categories: Class I, Class II (Divisions 1 and 2) and Class
III.19
The definition of normal occlusion proposed by Angle
did not take in consideration some other important
characteristics observed in individuals with excellent
occlusion. This lack of information came to an end when
Andrews, in 1972, published “The six keys to normal
occlusion”.21 He analyzed six significant characteristics
observed in a study of 120 casts of non-orthodontic
individuals with normal occlusion. The characteristics
included proper molar relationship, proper crown
angulation, proper crown inclination, no rotations, tight
contacts, and a flat occlusal plane. Andrews noted that
although normal individuals are one of a kind and the
models evaluated in his research differed in some respects,
all shared these six characteristics. This research led to
the development of brackets with prescribed dimensions,
which would reflect the ideal position of each tooth in all
three planes of space. Andrews‟ six keys expanded Angle‟s
original definition of normal occlusion.
4
Prevalence of Normal Occlusion
Studies of Caucasians residing in the United States
have shown differences in the prevalence of normal
occlusion, with percentages ranging from 4.7% to 30%.1-4 The
differences are probably due to the use of different
definitions of what can be considered normal or abnormal.
Some studies are stricter in their evaluation and classify
normal as having, at most, only a few teeth slightly out of
alignment and a Class I molar relationship.3,22 Others
classify normal as having up to 10 teeth out of alignment
and no orthodontic treatment indicated or desirable.1,4
Massler and Frankel, in a study with a sample of 2758
adolescents, found that 21.2% of the subjects had normal
occlusion, meaning no need for orthodontic treatment.1
Findings of another epidemiologic study by Mills showed
that 17.5% of the adolescents were considered having normal
occlusion.3 Surprisingly, another similar study from the
same year (1965), among senior high school students in
upstate New York, showed that only 4.7% of the individuals
had normal occlusion, but 69.9% were classified as Class I
malocclusion, which seems to be higher than what most of
the studies have found. This suggests that a stricter
pattern of classification for normal occlusion was used.2
5
In countries where there is more of a mix of races,
like Brazil, the prevalence of normal occlusion can be
somewhat lower than in the United States. There is no
evidence that this is due to the mixture of races, but is
interesting to notice such a difference. In a study of
Silva Filho et al, with a sample of 2,416 children, they
found that only 11.47% of the children had normal
occlusion.22
Hartsfield seems to imply that an increase in
malocclusion occurs as the populations become more
urbanized. This has been attributed to the interbreeding of
populations with, to some degree, different physical
characteristics, resulting in a disharmony of tooth and jaw
relationships,23 but there is no evidence in the current
literature to support such beliefs.
During 1966-70, the National Center for Health
Statistics conducted a survey that collected information
about the health of U.S. population aged 12-17 years.24 A
total number of 6,757 youths were examined and the buccal
segment relation recorded. They found that 53% of the
youths had neutrocclusion or Class I molar relationship,
32% had distocclusion or Class II, and 14% were classified
as having mesiocclusion, but only 2.5% had anterior
crossbite characteristic of a Class III malocclusion. They
6
also classified the severity of malocclusion and according
to this, 11% were classified as having normal occlusion,
and 34.8% as having only minor manifestations of
malocclusion. Years later (from 1988 to 1991), the same
National Center conducted the third National Health and
Nutrition Examination Survey (NHANES III). This study of
some 7,000 individuals was statistically designed to
provide weighted estimates for approximately 150 million
persons in the sampled racial/ethnic and age groups.
Profitt et al used the information from this national
survey to estimate the prevalence of malocclusion in the
United States. From their calculations, they found that, at
the most, 30% of the population had Angle‟s normal
occlusion.4
7
Class II, Division 2 Malocclusion
Definition
The classical and first definition of Class II,
Division 2 malocclusion comes from Angle in the Treatment
of Malocclusion of the Teeth from 1907,19 where he states
that it is the malocclusion characterized specifically by
distal occlusion of the teeth in both lateral halves of the
lower dentition, indicated by the mesiodistal relations of
the first permanent molars, but with retrusion instead of
protrusion of the upper incisors.
Angle also identified some other features saying that
the result of distal occlusion and recession of the jaw and
chin greatly mars the facial lines. He states that this
facial deformity is caused by a deficiency in vertical
growth and a more distal position of the mandible. Angle
commented having usually observed abnormal overbite and the
upper incisors tipping down and lingually. He also thought
that the lingual tipping of the lower incisors was a result
of the molars not erupting to the normal vertical height.
Milo Hellman studied Class II, Division 2 and
described additional characteristics of the malocclusion
stating that in Class II, Division 2, the mandible
approximates the normal in its anteroposterior dimension
and in its position, and that the maxilla is positioned
8
forward. He also emphasized another important feature, a
deficiency in vertical growth. Hellman stated that the
total facial height is less in Class II, Division 2, mainly
due to the shorter symphyseal and dental heights, despite
the fact that the upper face and nasal heights are greater
than in Class I.25
Controversies about the position of the mandible and
maxilla in Class II, Division 2 subjects have been
appearing ever since the first observational studies were
published many years ago.
Figure 2.1: Dental appearance of Class II, Division 2
9
Etiology
In the past some authors have tried to explain how
Class II, Division 2 malocclusion develops, but the
literature regarding to its etiology remains inconclusive.
Angle was the first to share his thoughts when he wrote
about the width of the arches being more nearly normal and
noticing less abnormal elevation of the lower incisors,
probably on account of their better opportunity for
performing their function. He also noticed an abnormal
overbite resulting from the upright position of the upper
incisors. He believed that since there are usually no
breathing problems, patients have their mouths closed most
of the time and the constant pressure of the lips results
in retrusion of the upper incisors during eruption until
they come into contact with the lower incisors.19
Following Angle, the members of the Eastern Component
Group of the Angle Society of Orthodontia conducted a
clinical study of cases with Class II, Division 2,26 where
they tried to identify the etiological factors associated
with the malocclusion. According to their observations,
they listed the following aspects:
(a)
Dysfunctional activity of the muscles of the lips
causing a backward driving force
(b)
Excessive action of the mentalis muscles
10
(c)
Abnormal swallowing function, especially the
first stage, in the form of exaggerated sucking
action
(d)
Premature loss of deciduous molars
(e)
Hypertoned, tense musculature of lips
(f)
Hypertrophy of the musculature of the cheeks
(g)
Nervous, high strung temperament
(h)
Malnutrition in early infancy (pointing to
disturbance of calcium metabolism)
(i)
Hypertrophy of the mentalis muscles
(j)
Distal pull by muscles attached to hyoid bone
(k)
Posture habit
(l)
Retarded forward growth of the mandible due to
muscular pressure
They also noted a lack of vertical growth of the
mandible, especially in the molar and premolar regions,
which they speculated was due to a failure in metabolic or
developmental processes during early childhood, maybe
related to malnutrition. For this group, the true Class II,
Division 2 malocclusion should always present mandibular
retrusion and it was attributed to an exaggerated
undergrowth in the body of the mandible.
Based only in clinical deductions, Strang27 believed
that heredity was an important factor for the occurrence of
11
Class II, Division 2 malocclusions. For him, the faulty
growth patterns of facial and cranial structures were
caused by the lack of vertical growth below the nose and by
the distal positioning of the mandible. He also believed
that a dysfunction in muscular activity, causing pressure
against the maxillary central incisors, combined with the
deep bite, were mechanical factors that needed to be
considered in the distal positioning of the mandible.27
In another study involving a small sample of only 15
patients, Hedges28 concluded that Class II, Division 2 was
not a specific stereotyped clinical syndrome. He believed
that the problem develops as the result of compensatory
variation, eruptive disharmony and muscular pressure, all
combined to form the malocclusion.
In a more recent study, Peck et al.29 found that the
mesio-distal tooth diameters for the maxillary and
mandibular incisors of subjects with Class II, Div. 2
malocclusion were significantly smaller than the teeth of
subjects with normal occlusion, suggesting that the
reduction in tooth size is a trait associated with the
malocclusion and an indicative of the presence of strong
genetic influences in the formation of Class II, Division 2
with deep-bite. Their findings were consistent with other
previous studies that found statistically significant
12
tooth-size reductions only in Class II, Div. 2
individuals.30,31
The etiology of Class II, Division 2 malocclusion is
uncertain like it is for any other type of malocclusion.
Profitt20 believed that contemporary research has refuted
the simplistic picture of malocclusion as resulting from
independent inheritance of dental and facial
characteristics. He states that the research findings
consistently have shown that there are no simple
explanation for malocclusion in terms of oral function and
that mouth breathing, tongue thrusting, soft diet, sleeping
posture, none can be regarded as the sole or even the major
reason for most malocclusions. Profitt also pointed out
that research has not yet clarified the precise role of
heredity as an etiologic agent for malocclusion and that
conclusions about the etiology of most orthodontic problems
are difficult, because several interacting factors probably
play a role. The current thought is that craniofacial
dimensions are mostly a result of heritable patterns and
dental arch variations have low heritability, but exactly
how this relates to the etiologic process of malocclusions
that have both skeletal and dental components remains
unknown.
13
Prevalence of Class II, Division 2 Malocclusions
The percentage of individuals with Class II, Division
2 malocclusion in the population is small. Studies in
Caucasian population found this percentage to be between
2.3% and 5%, representing around 3.4% of all
malocclusions.1-4,22
Studies of different ethnic groups confirm that Class
II, Division 2 malocclusion is more prevalent in
Caucasians. For instance, in African-Americans, the
prevalence of this malocclusion was reported to be 1.6%.32
In an Arab population, 1.7% of the subjects were classified
as Class II, Division 2.33 It appears to be least prevalent
among the Chinese, who have been reported to have a
prevalence of only 1%.34
Morphologic Characteristics of Class II, Division 2
Subjects
A reasonable number of studies have been dedicated to
describing the cephalometric and facial characteristics of
subjects with Class II, Division 2 malocclusion. Despite
all of the work that has been done, much controversy still
exists as to what a Class II, Division 2 malocclusion
14
actually looks like. Several researchers have stated that
the malocclusion is characterized by an orthognathic facial
pattern and a malocclusion that is mostly
dentoalveolar.6,9,11,14 Others found that Class II Division 2
malocclusion has unique skeletal and dentoalveolar
characteristics.8,10,16-18 A summarized description of the
controversial findings of previous studies in untreated
Class II, Division 2 subjects is shown in table 2.1.
Balridge, evaluating the cephalograms of 21 Class II,
Division 2 and 50 Class I subjects found that the mandible
is in the correct antero-posterior relation to the face and
cranium but may be longer than the mandible of Class I
subjects.35 In a similar study, Renfroe also found no lack
of mandibular development, indicating that the maxilla was
definitely further forward in Class I and Class II Division
2 than in Class II Division 1 cases.11 He also found that
the position of the maxillary first molar was almost
identical in both divisions of Class II, which is slightly
posterior to the position of the molar in Class I‟s. In
addition, while the mandibular dental arch is positioned
posteriorly in Class II Division 2, the chin is positioned
almost as far forward as in Class I‟s and the gonial angle
is usually larger in Class I‟s. In accordance to these
findings, Blair12 noted
that the mean skeletal pattern of
15
Class II, Div.2 malocclusion, when compared with those of
Class I and Class II Div.1 cases, differs in having a more
acute gonial angle. Blair also found a decreased length of
the mandible and a more forward position of the anterior
portion of both mandible and maxilla.
Findings of Wallis support the idea that Class II
Division 2 subjects represent a significantly distinct
population.18 In this study, all aspects of the cranial base
(BaN, BaS, BaSN angle) with the exception of anterior
cranial base were consistently larger than in Class I
controls and Class II Division 1 cases. Also, the
relatively small gonial and mandibular plane angles, the
smaller body length and normal ramus height, gave the
Division 2 mandible its distinction.18 Similarly, Houston5
found cranial base length to be significantly greater, and
the mandibular angle and lower facial height to be smaller
in a Class II Division 2 group than in a neutrocclusion
group.
In disagreement with these previous findings,
Godiawala and Joshi,16 studying an Indian population,
reported normal cranial base length, normal facial height,
and normal mandibular position among Class II Division 2
subjects compared to the normal control group. The only
difference that they found was a slightly smaller
16
mandibular length and retroclined central incisors among
the Class II, Division 2 cases. In another cross sectional
study, Hitchcock reported that the mandible was slightly
retro-positioned, but the maxilla was in the same position
of that in Class I subjects.13
Maj and Lucchese17 evaluated a sample of 60 Class II
Division 2 subjects in their study, with the main objective
being the description of the mandible in Class II Division
2 cases. They found a unique skeletal pattern, smaller
gonial angle and hyperdevelopment of various parts of the
mandible (e.g.; excessive development of ramus height and a
prominent chin).
Fischer-Brandies et al.14 compared a sample of 56 adult
Class II Div. 2 individuals with 81 adult Class I‟s with
normal occlusion. They found no significant differences
between the groups, with the exception of B point, which
was retropositioned among the Class II Div. 2 adults.
Mandibular retrognathia was one of the most important
findings by Karlsen,6 who only included patients with
extreme deep bites and Class II, Division 2 malocclusion.
The mandible was also smaller (especially the corpus), as
was anterior facial height. Incisal height was slightly
larger, molar height was slightly smaller and the
17
interincisal angle was much larger among Class II Division
2 subjects than normal subjects.
Pancherz et al.7 compared the cephalometric
characteristics of children from 8 to 13 years of age with
Class II division 1 and Class II division 2 malocclusions.
They found a high frequency of cases with mandibular
retrusion (around 48%) in both groups and short lower face
heights for almost all subjects (97%) with Class II
Division 2. They concluded that there were no basic
differences in dentoskeletal morphology between subjects
with Class II Division 1 and Class II Division 2
malocclusions.
Brezniak et al. performed a study involving 50
patients who fit Angle‟s original criteria for a Class II
Division 2 malocclusion, which includes mandibular
retrognathia.8 Their findings demonstrate unique skeletal
and dentoalveolar characteristics among Class II Division 2
subjects. While their maxillas were orthognathic, the
mandibles were relatively short and retrognathic, the chins
were prominent, the facial pattern was hypodivergent, the
upper incisors were retroclined and the overbite was deep.
They suggested that the morphological characteristics of
individuals with Class II Division 2 malocclusion fell
18
between individuals with Angle Class I‟s and Angle Class II
Division 1 malocclusions.
Isik et al.9 suggested that differences in the methods
used to register maxillary position may explain the
differences among studies. Comparing Class II Division 2
and Class II Division 1 subjects, they found that the SNB
angle was responsible for the skeletal sagittal difference
between the two groups. The SNB angle indicated mandibular
retrusion for Class II Division 1 and almost normal
mandibular positions for Class II Division 2 subjects, very
similar to mandibular position of Class I cases.
Recently, Al-Khateeb and Al-Khateeb compared a large
number of subjects with Class II division 1, Class II
Division 2 malocclusions and Class I normal occlusion.10
Their findings suggest that Class II Division 2 should be
considered as a separate entity, which differs in almost
all skeletal and dental features from Class I and Class II
Division 1. They indicated that individuals with Class II
Division 2 have prognathic maxilla, an orthognathic
mandible, diminished lower anterior facial height, normally
inclined lower incisors and increased interincisal angles.
A summarized description of all studies is provided in
table 2.1.
19
Table 2.1: Comparative cephalometric studies describing Class II, Division 2 characteristics
Author (Date)
Sample (N)
Class II Div.2
Findings
Max. Mand. Dent-alv. Cr. Base
20
Balridge (1941)
Cl I (50)
Cl II Div. 1 (32)
Cl II Div.2 (21)
Renfroe (1948)
Cl I (43)
CL II Div.1 (36)
Cl II Div.2 (16)
Blair (1954)
CI (40)
Cl II Div.1 (40)
Cl II Div. 2 (20)
Normal development of the mandible, Maxilla is further forward
Dental arches are positioned back in their skeletal bases
Position of chin is the same as Class I
Border of the mandible is flat and horizontal
More acute gonial angle
Decreased mandibular length
Forward position of the anterior portion of mandible and maxilla
Wallis (1963)
Cl I (47)
Cl II Div.1 (105)
Cl II Div.2
Smaller mandibular body and normal ramus height
Acute gonial and mandibular plane angles
Cranial base angles are all larger
Houston (1967)
Cl I (96)
Cl II Div.1 (96)
Cl II Div.2 (96)
Cranial base length is larger
Mandibular plane angle and lower facial height are smaller
Godiawala &
Joshi (1974)
Cl I (30)
Cl II Div.2 (25)
Normal cranial base length and vertical face height
Maxilla and mandible are in normal position
Mandibular length slightly smaller
X
Hitchcock (1976)
Cl I (40)
Cl II Div.1 (57)
Cl II Div.2 (42)
Mandible is retro-positioned compared to Cl I
Maxilla is in the same position as Cl I
X
Maj & Lucchese (1982)
Cl I (28)
Cl II Div.2 (60)
Smaller gonial angle
Prominent chin
Hyperdevelopment of component parts of the mandible
X
Fischer-Brandies (1985)
Cl I (81)
Cl II Div.2 (56)
Karlsen (1994)
Cl I (25)
Cl II Div.2 (22)
Mandible is probably longer
Mandible is in correct antero-posterior position in relation to the cranial base
X
X
X
X
X
X
Cl II Div.1 (347) No difference in dentoskeletal morphology between Cl II Div. 1 and Class II Div.2
Cl II Div.2 (156)
Mandibular retrusion and short lower facial height
Maxilla is normal positioned
Cl I (34)
Mandible is short and retrognathic
Brezniak et al. (2002) Cl II Div.1 (54)
Prominent chin
Cl II Div.2 (50)
Deep overbite and hypodivergent pattern of growth
Pancherz et al. (1997)
Cl II Div.1 (46)
Cl II Div.2 (44)
SNB showed almost normal values for Class II Div.2 (similar to Cl I)
Severe deep bite probably inhibits forward mandibular dentoalveolar growth
Prominent chin
Al-Khateeb &
Al-Khateeb (2009)
Cl II Div.1 (293)
Cl II Div.2 (258)
Should be considered as a separate entity
Prognathic maxilla / Orthognathic mandible
Increased interincisal angle and decreased lower facial height
X
X
B point is back meaning retro-position of the alveolar bone on the mandible
Chin is in a more normal position
Mandible is smaller (especially corpus)
Underdeveloped anterior facial height
Smaller molar height and larger interincisal angle
Isik et al. (2006)
X
X
X
X
X
X
Cross Sectional Versus Longitudinal Studies
Most of the previous studies were cross sectional in
design with different sample sizes and methods. If the
sample size is too small, it may make it difficult to
generalize the findings to a larger group. Some cross
sectional studies analyzed the data of large craniofacial
databases to infer conclusions for longitudinal changes in
subjects with Class I and Class II malocclusions,36-38 but
following the subjects over time is a more appropriate
approach. Cross-sectional studies involve studying groups
of participants in different age groups at the same point
in time, thus the researcher does not gain the rich data on
individual development that can be obtained from
longitudinal studies, since the evidence of change is
inferred from differences between the age groups. Age
differences may show trends particular to a specific group
and not true developmental changes. In a longitudinal
study, the researcher performs repeated observations at
specified points during the subjects' lives, thus allowing
the observation of development. This design provides the
best information about the continuity or discontinuity of
growth patterns over time and allows for the individual
tracking of these patterns, as well as trends of
21
development, within a similar group. The important aspect
is that longitudinal studies extend beyond a single moment
in time. As a result, they can establish sequences of
events.39,40
Dentofacial Development of Untreated Normals
In order to study the differences in dentofacial
development of individuals with Class II Division 2
malocclusion, it is important to identify the skeletal and
dental changes that occur in the untreated individuals with
normal occlusion.
In 1985, Sinclair and Little conducted a longitudinal
study41 using cephalometric head films from a sample of 65
untreated normal persons, which were evaluated to determine
the nature and extent of the normal dentofacial maturation
process. They selected three time points: mixed dentition
(9 to 10 years), early permanent dentition (12 to 13 years)
and early adulthood (19 to 20 years). Their most important
findings for normal craniofacial development included the
following:
(a)
The amount and direction of maxillary growth are
related to the amount of anteroposterior mandibular growth.
22
(b)
Late mandibular growth included a forward
rotation of the mandible occurring post-puberty during the
period of reduction of vertical maxillary growth.
(c)
Anteroposterior growth of the mandible is
associated with the direction of condylar growth, which
depends on the total amount of condylar growth.
(d)
Changes in sagittal jaw relations are associated
with the interrelationship between skeletal and dental
changes in the vertical and sagittal planes.
(e)
The degree of vertical eruption of the upper and
lower molars is associated with the amount of forward
mandibular rotation.
(f)
Males grow more than females in all parameters,
especially after puberty. They matured later.
(g)
Incisor angulation relative to the cranial base
was relatively stable, suggesting that the teeth compensate
to the skeletal changes that occur in order to maintain the
occlusal relationships.
In a series of longitudinal cephalometric implant
studies, Björk described the various aspects of
craniofacial growth.42,43 He found that the mandible becomes
more prognathic in relation to the maxilla as individuals
age, and that for most cases the mandible and the maxilla
rotate forward in a counter-clockwise direction relatively
23
to the anterior cranial base. This forward rotation should
be considered a normal growth pattern, but some subjects
showed backward rotation as well. He also showed that the
amount of teeth eruption compensates for vertical growth of
the craniofacial complex and that there is a forward
migration of the mandibular dentition during eruption, with
proclination of the incisors and an increase in the
alveolar prognathism. Björk pointed out that the mandibular
shape is practically unchanged during growth because of
remodeling process at the mandibular surfaces. He also
noted that the eruption paths of the teeth indicated a
marked growth in height of the alveolar process.
These findings from Sinclair, Little and Björk
summarize the craniofacial characteristics of the normal
development and should be taken into consideration when
analyzing the developmental changes of Class II, Division 2
subjects.
24
References
1.
Massler M, Frankel JM. Prevalence of malocclusion in
children aged 14 to 18 years. Am J Orthod. 1951
Oct;37(10):751–68.
2.
Ast DB, Carlos JP, Cons NC. The prevalence and
characteristics of malocclusion among senior high school
students in upstate New York. Am J Orthod. 1965
Jun;51:437–45.
3.
Mills LF. Epidemiologic studies of occlusion. IV. The
prevalence of malocclusion in a population of 1,455
school children. J Dent Res. 1966 Apr;45(2):332–6.
4.
Proffit WR, Fields HW Jr, Moray LJ. Prevalence of
malocclusion and orthodontic treatment need in the
United States: estimates from the NHANES III survey. Int
J Adult Orthodon Orthognath Surg. 1998;13(2):97–106.
5.
Houston WJ. A cephalometric analysis of Angle Class II,
Division II malocclusion in the mixed dentition. Dent
Pract Dent Rec. 1967 Jun;17(10):372–6.
6.
Karlsen AT. Craniofacial characteristics in children
with Angle Class II div. 2 malocclusion combined with
extreme deep bite. Angle Orthod. 1994;64(2):123–30.
7.
Pancherz H, Zieber K, Hoyer B. Cephalometric
characteristics of Class II division 1 and Class II
division 2 malocclusions: a comparative study in
children. Angle Orthod. 1997;67(2):111–20.
8.
Brezniak N, Arad A, Heller M, Dinbar A, Dinte A,
Wasserstein A. Pathognomonic cephalometric
characteristics of Angle Class II Division 2
malocclusion. Angle Orthod. 2002 Jun;72(3):251–7.
9.
Isik F, Nalbantgil D, Sayinsu K, Arun T. A comparative
study of cephalometric and arch width characteristics of
Class II division 1 and division 2 malocclusions. Eur J
Orthod. 2006 Apr;28(2):179–83.
10.
Al-Khateeb EAA, Al-Khateeb SN. Anteroposterior and
vertical Components of Class II division 1 and division
2 malocclusion. Angle Orthod. 2009 Sep;79(5):859–66.
25
11.
Renfroe E. A study of the facial patterns associated
with Class I, Class II, Division 1, and Class II,
Division 2 malocclusions. Angle Orthod. 1948;18:12–5.
12.
Blair ES. A cephalometric roentgenographic appraisal
of the skeletal morphology of Class I, Class II, Div. 1,
and Class II, Div. 2 (Angle) malocclusions. Angle
Orthod. 1954;24:106–19.
13.
Hitchcock HP. The cephalometric distinction of Class
II, division 2 malocclusion. Am J Orthod. 1976
Apr;69(4):447–54.
14.
Fischer-Brandies H, Fischer-Brandies E, König A. A
cephalometric comparison between Angle Class II,
division 2 malocclusion and normal occlusion in adults.
Br J Orthod. 1985 Jul;12(3):158–62.
15.
Cleall JF, BeGole EA. Diagnosis and treatment of Class
II division 2 malocclusion. Angle Orthod. 1982
Jan;52(1):38–60.
16.
Godiawala RN, Joshi MR. A cephalometric comparison
between Class II, division 2 malocclusion and normal
occlusion. Angle Orthod. 1974 Jul;44(3):262–7.
17.
Maj G, Lucchese FP. The mandible in Class II, division
2. Angle Orthod. 1982 Oct;52(4):288–92.
18.
Wallis S. Integration of certain variants of the
facial skeleton in Class II, division 2 malocclusion.
Angle Orthod. 1963 Jan;33(1):60–7.
19.
Angle E. Treatments of Malocclusion of the Teeth. 7th
ed. Philadelphia: S.S. White Dent. Mfg. Co.; 1907.
20.
Proffit WR. Contemporary Orthodontics. 4th ed. Saint
Louis, MO: Mosby / Elsevier; 2007.
21.
Andrews L. The six keys of normal occlusion. Am J
Orthod. 1972 Sep;62(3):296–309.
22.
da Silva Filho OG, de Freitas SF, Cavassan A de O.
[Prevalence of normal occlusion and malocclusion in
Bauru (Sao Paulo) students. 1. Sagittal relation]. Rev
Odontol Univ Sao Paulo. 1990 Jun;4(2):130–7.
26
23.
Graber TM, editor. Orthodontics: Current Principles
and Techniques. 4th ed. Saint Louis, MO: Elsevier /
Mosby; 2005.
24.
Kelly JE, Harvey CR. An assessment of the occlusion of
the teeth of youths 12-17 years. Vital Health Stat 11.
1977 Feb;(162):1–65.
25.
Gregory WK. Milo Hellman‟s studies on the evolution of
the teeth, jaws, and face. Am J Orthod. 1947
Jan;34(1):53–60.
26.
Eastern Component Group. A clinical study of cases of
malocclusion in Class II, Division 2. Angle Orthod.
1935;5:87–106.
27.
Strang R. Class II, division 2 malocclusion. Angle
Orthod. 1958 Oct;28(4):210–4.
28.
Hedges RB. A cephalometric evaluation of Class II,
division 2. Angle Orthod. 1958 Oct;28(4):191–7.
29.
Peck S, Peck L, Kataja M. Class II Division 2
malocclusion: a heritable pattern of small teeth in
well-developed jaws. Angle Orthod. 1998 Feb;68(1):9–20.
30.
Beresford J. Tooth size and class distinction. Dent.
Pract. 1969;20:113–20.
31.
Robertson NR, Hilton R. Feature of the upper central
incisors in Class II Division 2. Angle Orthod. 1965
Jan;35:51–3.
32.
Altemus, L. Frequency of the incidence of malocclusion
in American Negro children aged twelve to sixteen. Angle
Orthod. 1959 Oct;29(4):189–200.
33.
Zilberman S, Kawar,. Prevalence and severity of
malocclusion in Israeli Arab urban children - 13 to 15
years of age. Am J Orthod. 1983;84(4):337–43.
34.
Perng C, Lin J. Preliminary study of malocclusion of
pedodontic patients in Veterans General Hospital. Taiwan
Clin Dent. 1983;3:19–26.
35.
Balridge JP. A Study of the Relation of the Maxillary
First Permanent Molars to the Face in Class I and Class
II Malocclusions. Angle Orthod. 1941 Apr;11(2):100–9.
27
36.
McNamara J. Components of Class II malocclusion in
children 8–10 years of age [Internet]. 2009 Jul 15
[cited 2011 Nov 24]; Available from:
http://www.angle.org/doi/abs/10.1043/0003.
37.
Anderson DL, Popovich F. Lower cranial height vs
craniofacial dimensions in Angle Class II malocclusion.
Angle Orthod. 1983 Jul;53(3):253–60.
38.
Riesmeijer AM, Prahl-Andersen B, Mascarenhas AK, Joo
BH, Vig KWL. A comparison of craniofacial Class I and
Class II growth patterns. Am J Orthod Dentofacial
Orthop. 2004 Apr;125(4):463–71.
39.
Methods of studying children - longitudinal versus
cross-sectional studies. Blog Post. Available from:
http://social.jrank.org/pages/411/Methods-StudyingChildren-Longitudinal-versus-Cross-SectionalStudies.html
40.
Stan A. Cross sectional vs longitudinal studies. At
Work Magazine, Toronto. 2009; Winter(55):7.
41.
Sinclair PM, Little RM. Dentofacial maturation of
untreated normals. Am J Orthod. 1985 Aug;88(2):146–56.
42.
Björk A. Variations in the growth pattern of the human
mandible: longitudinal radiographic study by implant
method. J Dent Res. 1963;42(1):400–11.
43.
Björk A, Skieller V. Normal and abnormal growth of the
mandible. A synthesis of longitudinal cephalometric
implant studies over a period of 25 years. Eur J Orthod.
1983 Feb;5(1):1–46.
28
CHAPTER 3: JOURNAL ARTICLE
Abstract
Objective: To more fully characterize the growth of
untreated Class II, Division 2 malocclusion subjects 6-19
years of age. Materials and Methods: Mixed-longitudinal
cephalograms of 39 Caucasian Class II, Division 2 subjects
were analyzed at five time points: T1 (6-7ys), T2 (9-10ys),
T3 (12-13ys), T4 (15-16ys) and T5 (18-19ys). They were
compared to an age and sex matched sample of normal Class I
controls. A total of 17 variables (12 angular and 5
proportional) were evaluated using Dolphin Imaging
software. Multilevel modeling procedures were used to
statistically evaluate the growth changes that occurred and
to determine group differences. Results: Multilevel
statistical models showed significant group differences for
seven of the 17 variables. Class II, Division 2 subjects
(12-13 years of age) demonstrated significantly (p<0.05)
smaller mandibular plane angles, smaller palatal plane to
mandibular plane angles, smaller cranial base angles (Ba-SN) and smaller U1SN angles than Class I‟s. They also had
significantly larger U1L1 angles and greater posterior to
anterior facial heights (PAFHp). The gonial angles of Class
II, Division 2 subjects were significantly smaller than the
gonial angles of Class I‟s at the 18-19 years of age.
29
Significant growth differences were also demonstrated, with
Class II, Division 2 subjects showing greater decreases of
the mandibular and palatal plane angles, greater increases
of the PAFH ratio, and smaller changes of U1-SN angle.
Conclusions: Compared to the Class I‟s, Class II, Division
2 subjects have smaller cranial base angles, more
horizontal growth patterns and more upright incisors. Most
of the differences are evident at the early ages and
increase over time.
30
Introduction
Class II, Division 2 malocclusion is not a common form
of malocclusion.
Its prevalence has been estimated to
range between 2.3% and 5% among Caucasians.1-5 This type of
malocclusion appears to be more common among Caucasians
than other ethnic groups.6-8
The etiology of Class II, Division 2 malocclusion,
remains unclear.9 Peck et al. showed that the reductions in
tooth size were associated with Class II, Division 2
malocclusions, suggesting a strong genetic influence.
Tooth-size reductions have been repeatedly reported in
Class II, Division 2 individuals.10,11 In addition, familial
occurrence of Class II, Division 2 has been documented in
several reports including twin and triplet studies and in
family pedigrees.12-14
Since Angle first characterized the malocclusion based
on distal occlusion of the lower dentition and retrusion,
rather than protrusion, of the upper incisors, there has
been considerate confusion concerning the morphologic
characteristics of growing subjects with Class II, Division
2 malocclusion.15 It has been suggested that this form of
malocclusion is mostly dentoalveolar (i.e., that the
skeletal components are largely unaffected).16-19 Others have
demonstrated either a lack of mandibular development16,20-23
31
among Class II, Division 2 subjects or retro-positioning of
the mandible.23,24
Increased cranial base lengths24 and
larger cranial base angles23 have also been found,
suggesting that the mandible is retro-positioned because it
articulates with a longer, flatter cranial base. Two
studies noted prognathic maxillas as the main feature of
the malocclusion.18,25
Most previous studies have been cross-sectional in
design and limited in scope. Cross-sectional studies are
only able to compare groups at one point in time, which
makes it difficult to evaluate growth changes, especially
variation in the growth changes that take place. Moreover,
the majority of the studies have evaluated subjects between
12-15 years of age, making it difficult to determine how
the malocclusion develops. There are no longitudinal
studies of untreated Class II, Division 2 subjects followed
over extended age ranges. Studies that do not provide
statistical comparisons involving controls make it
difficult to determine whether differences actually exist.
Finally, most of the samples sizes have been small,1618,21,22,26,27
ranging from 16 to 25 individuals, which can
compromise statistical comparisons.
The purpose of this study was to evaluate growth of
untreated Class II, Division 2 subjects using serial
32
cephalograms (6-19 years) and to characterize the
malocclusion through comparisons to untreated Class I
subjects with normal occlusion matched by age and gender.
Materials and Methods
Sample
The study samples came from the archives of two growth
studies: the Bolton-Brush Growth Study Center at Case
Western Reserve University and the Human Growth and
Research Center at the University of Montreal. The data
consisted of 305 mixed-longitudinal cephalograms (ages 6 to
19 years) from untreated individuals. The subjects were
chosen based on the following criteria: (1) Class II,
Division 2 malocclusion, based on the Angle classification,
(2) a minimum of two mixed-longitudinal cephalograms
available at five time points (6-7 years, 9-10 years, 12-13
years, 15-16 years, and 18-19 years), (3) cephalograms had
to be of sufficient quality for landmark identification,
(4) no prior treatment, and (5) no major craniofacial
anomalies.
The untreated Class II, Division 2 sample consisted of
39 subjects, including 17 from the Bolton-Brush Growth
33
Study and 22 from the Human Growth Study of the University
of Montreal. Approximately 21% of the sample had
cephalograms available at all five timepoints; 61% had
cephalograms available at four timepoints, 13% had
cephalograms available at 3 timepoints, and the remaining
5% of the sample had cephalograms available at 2 time
points.
The Class II, Division 2 sample was matched based on
age and sex to a Class I control sample. The control sample
consisted of 35 subjects, including 10 from the BoltonBrush Growth Study and 25 from the Human Growth Study of
the University of Montreal. Approximately 29% of the
control subjects had cephalograms available at all
timepoints and 71% having cephalograms at 4 timepoints
(Table 3.1).
34
Table 3.1: Age and Gender Distribution of Study Sample
Group
Males:Females
6-7ys
Mean Age ± SD
(Range)
9-10ys
Mean Age ± SD
(Range)
12-13ys
Mean Age ± SD
(Range)
15-16ys
Mean Age ± SD
(Range)
18-19ys
Mean Age ± SD
(Range)
35
Untreated
Class II
Div.2
22:17
*N=23
6.2 ± .46
(5y9m-7y)
*N=34
9.5 ± .50
(8y9m-10y)
*N=39
12.3 ± .53
(11y-13y4m)
*N=37
15.3 ± .61
(13y9m-16y)
*N=22
17.9 ± 1.0
(17y4m-20y6m)
Untreated
Class I
Control
18:17
*N=23
6.2 ± .42
(6y-7y1m)
*N=35
9.6 ± .59
(8y9m-11y)
*N=35
12.5 ± .49
(12y-13y)
*N=35
15.4 ± .61
(14y-16y2m)
*N=22
18.4 ± .66
(17y-19y)
*N = number of cephalograms available at each time point.
Methodology
Cephalograms were traced using a 0.3 mm mechanical
pencil and acetate paper (0.003”). The tracings were
performed by the principal investigator (LAB) and checked
for accuracy by another investigator (RGB). Any
disagreements were resolved by retracing the anatomical
structure to the satisfaction of both observers.
The
tracings were scanned at 300 dpi, stored as digital images
(TIFF file format), and transferred to Dolphin Imaging 10.5
(manufacturer, city) software for the analyses.
Using a customized cephalometric analysis created in
Dolphin Imaging 10.5 software, the scanned tracings were
digitized. Seventeen landmarks were identified based on
standardized definitions (Table 3.2); they were chosen in
order to fully characterize the cranial base, midface, and
mandible (Figure 3.1).
36
Table 3.2: Definitions and abbreviations of the landmarks.28
Landmark
Abbrev
A Point
A
Anterior
Nasal Spine
ANS
Articulare
Ar
B Point
B
Basion
Ba
Gnathion
Gn
Gonion
Go
Lower Incisor
root apex
Lower Incisor
edge tip
Lower First
Molar
Occlusal
L1-A
L1-E
L6-Occ
Menton
Me
Nasion
N
Posterior
Nasal Spine
Pogonion
Sella
Upper Incisor
Root Apex
Upper Incisor
edge tip
PNS
Pog
S
U1-A
U1-E
Definition
The most posterior point in the concavity
between ANS and the maxillary alveolar
process
The anterior tip of the nasal spine
The intersection of the posterior border of
the ramus and the inferior border of the
posterior cranial base
The most posterior point in the concavity
between the chin and the mandibular process
The most inferior-posterior point on the
anterior margin of the Foramen Magnum in the
midsagittal plane
The point midway between the anterior and
inferior points on the border of the chin
The point on the curvature of the mandible
located by bisecting the angle formed by the
lines tangent to the posterior ramus and the
inferior border of the mandible
The tip of the root apex of the mandibular
central incisor
The tip of the incisal edge of the mandibular
central incisor
The anterior cusp tip of the mandibular first
molar
The most inferior point of the mandibular
symphysis
The most anterior point of the frontonasal
suture
The most posterior point on the bony hard
palate
The most anterior point of the chin
The center of the pituitary fossa
The tip of the root apex of the maxillary
central incisor
The tip of the incisal edge of the maxillary
central incisor
37
Figure 3.1 – Anatomical landmarks
Because different x-ray machines were used to obtain
the cephalograms, only angular and proportional
measurements were compared. A customized cephalometric
analysis was created and the following 17 measurements
(Figure 3.2) were calculated:
-
12 angular measurements describing
anteroposterior relationship (SNA, SNB, ANB), growth
direction (N-S-Gn), vertical relationship (SN-GoGn, ANSPNS38
GoGn, Ar.Go.Gn, ANSPNS-SN), flexure of cranial base
angulation (Ba-S-N) and dental angulation (U1-L1, U1-SN,
IMPA);
-
5 ratios describing the anteroposterior
relationship between the cranial base and maxilla
(ANSPNS/SN), cranial base and mandible (GoGn/SN), maxilla
and mandible (GoGn/ANSPNS), and the vertical relationship
(posterior to anterior facial height ratio, L6 occlusal to
GoGn/L1 incisal to GoGn).
Figure 3.2: Cephalometric measurements
39
Statistical Analyses
Multilevel statistical models were used to evaluate
the growth changes over time and to compare the two groups.
These models, developed using iterative generalized least
squares, do not require complete longitudinal data or equal
time intervals.29,30 Multilevel models consist of random and
fixed parts. The fixed part of the model described the
average growth curve and average group differences. The
constant term of the polynomial models that were used was
set at T2. The random part of the model described variation
at two levels, with subjects at the higher level and
timepoints nested within subjects, at the lower level.
The first step was to determine the order of the
polynomial that “best fit” the groups‟ data. Fourth order
polynomials were first tested. If the fourth order term was
not statistically significant (p<.05), it was deleted and a
third order polynomial was tested. This continued,
sequentially eliminating higher order terms, until
statistical significance was attained.
The models also
statistically evaluated differences in the polynomial terms
between Class I and Class II, Division 2 subjects.
40
Results
Group Descriptive Statistics
The anteroposterior differences between maxilla and
mandible of Class I subjects decreased over time, primarily
due to mandibular protrusion (Table 3.3). Class I‟s showed
decreases in mandibular plane angles, palatal plane to
mandibular plane angles, gonial angles and cranial base
angles (Ba-S-N), and increases in posterior facial height
over time. Interincisal angles, U1-SN and IMPA showed also
increases over time, with proclination of the upper and
lower incisors. Class II, Division 2 subjects showed
hypodivergent growth patterns, with even larger posterior
facial heights and interincisal angles, smaller cranial
base angles (Ba-S-N), and upright upper incisors (Table
3.4).
41
Table 3.3 – Cephalometric Characteristics of Untreated Subjects with Class I Normal Occlusion from Early
Mixed Dentition to Adulthood
Cephalometric Measurements from Early Mixed Dentition to Adulthood
Time points →
42
Variable
SNA
SNB
ANB
Y-Axis
MP (GoGn-SN)
PP-MP
Ar-Go-Gn
PP (ANSPNS-SN)
Ba-S-N
U1-L1
U1-SN
IMPA
ANSPNSp* (%)
GoGnp* (%)
Mx:Mdp* (%)
PAFHp* (%)
L6:L1p* (%)
p* = Proportional
T1
T2
Mean
SD
Mean
81.6
3.5
81.0
76.9
2.4
77.3
4.7
2.5
3.7
67.7
2.5
67.1
34.8
3.4
33.3
28.9
4.0
26.2
124.7
7.5
120.0
6.0
2.8
7.1
130.7
4.3
129.9
140.9
12.5
130.4
95.2
6.5
102.4
86.9
6.5
93.1
72.5
4.5
72.7
97.5
7.0
99.2
75.4
6.1
74.5
61.8
3.3
63.2
78.1
5.3
74.7
(ratio) measurements.
T3
SD
3.2
2.5
1.8
3.0
4.2
4.4
9.1
2.6
3.7
9.0
5.4
6.9
4.2
6.1
4.9
3.5
4.1
Mean
81.3
77.9
3.4
67.2
32.9
25.3
120.1
7.6
129.7
130.8
101.1
94.2
72.6
102.4
72.7
63.7
74.8
T4
SD
3.3
2.5
2.4
3.2
4.9
5.0
9.1
3.1
3.8
8.8
5.5
7.0
4.9
6.5
5.3
3.8
3.3
Mean
81.3
78.4
2.9
67.5
31.9
23.9
120.6
8.0
129.8
132.0
101.2
93.9
73.8
105.2
72.1
65.1
76.7
T1-T5
(≠)
T5
SD
3.5
2.5
2.5
3.2
5.4
5.4
9.5
2.8
4.6
9.6
5.1
7.8
5.0
5.9
4.9
4.1
3.2
Mean
81.3
78.6
2.6
66.7
30.2
22.3
119.8
7.9
129.9
132.4
101.2
94.5
72.1
106.8
70.5
66.7
77.5
SD
2.6
2.1
2.2
3.1
4.8
5.5
9.0
2.7
5.6
9.1
5.3
7.2
3.8
5.9
3.1
3.3
4.4
-0.3
1.7
-2.1
-1.0
-4.6
-6.6
-4.9
1.9
-0.8
-8.5
6.0
7.6
-0.4
9.3
-4.9
4.9
-0.6
Table 3.4 - Cephalometric Characteristics of Untreated Subjects with Class II Division 2 Malocclusion from
Early Mixed Dentition to Adulthood
Cephalometric Measurements from Early Mixed Dentition to Adulthood
Time points →
Variable
43
SNA
SNB
ANB
Y-Axis
MP (GoGn-SN)
PP-MP
Ar-Go-Gn
PP (ANSPNS-SN)
Ba-S-N
U1-L1
U1-SN
IMPA
ANSPNSp* (%)
GoGnp* (%)
Mx:Mdp* (%)
PAFHp* (%)
L6:L1p* (%)
T1
Mean
82.1
77.2
5.1
66.2
31.4
24.7
118.9
6.6
128.0
147.1
93.5
86.3
73.1
96.5
75.5
64.7
78.7
T2
SD
2.5
2.5
1.5
2.6
2.9
4.2
8.0
2.9
3.6
11.1
7.7
6.4
4.3
5.2
3.4
3.1
6.0
p* = Proportional (ratio) measurements.
Mean
81.7
77.3
4.3
66.6
30.8
24.0
117.4
6.9
127.6
135.1
98.7
93.9
73.1
99.8
74.2
65.6
75.6
T3
SD
2.6
2.3
1.9
2.7
3.9
4.1
7.1
2.5
4.1
8.4
4.9
6.1
4.2
5.1
4.1
3.3
3.7
Mean
82.2
78.0
4.2
66.3
29.5
22.2
117.6
7.2
127.8
139.1
96.7
92.9
73.6
102.6
73.2
67.0
75.0
T4
SD
2.6
2.5
1.7
2.5
3.8
3.6
7.1
2.4
4.3
10.6
7.2
6.9
3.7
5.3
3.6
3.4
3.7
Mean
82.6
78.6
4.0
66.3
28.4
21.1
117.5
7.3
128.1
138.9
97.6
93.6
73.8
105.4
72.1
68.5
77.6
T1-T5
(≠)
T5
SD
2.8
2.4
2.0
2.8
4.5
4.3
7.4
2.3
4.4
9.1
5.9
6.5
3.8
5.2
3.7
4.0
4.6
Mean
82.0
78.5
3.5
66.5
28.1
20.6
118.3
7.5
128.3
140.1
98.1
91.5
72.5
106.3
71.5
68.7
76.7
SD
3.0
2.3
2.3
2.8
5.0
4.9
6.7
2.5
4.2
10.1
6.0
7.1
5.0
5.6
4.8
4.9
3.9
-0.1
1.3
-1.6
0.3
-3.3
-4.1
-0.6
0.9
0.3
-7.0
4.6
5.2
-0.6
9.8
-4.0
4.0
-2.0
Group Comparisons
The multilevel statistical models (Table 3.5) showed
statistically significant group differences for seven of
the 17 variables evaluated. Compared to 9-10 year old Class
I's, Class II, Division 2 subjects demonstrated
significantly (p<0.05) smaller mandibular plane angles,
smaller palatal plane to mandibular plane angles, smaller
cranial base angles (Ba-S-N), larger posterior to anterior
facial heights (PAFH ratio), larger U1-L1 angles, and
smaller U1-SN angles than Class I's. Although the
differences were not statistically significant at 9-10
years, the gonial angle of Class II, Division 2 subjects
was significantly (p<0.05) smaller than the gonial angle of
Class I‟s at 18-19 years of age.
Four variables also demonstrated significant growth
differences over time. The mandibular and palatal plane
angles showed significantly lower growth rates in Class II,
Division 2 than Class I subjects.
The PAFH ratio
increased significantly faster in Class II, Division 2 than
Class I subjects.
Finally, changes in U1-SN increased
(accelerated) significantly more in Class II's than Class
I's.
44
Table 3.5. Multilevel models describing the average growth changes of Class I subjects with
normal occlusion and differences between Class I and Class II, Division 2 subjects
Class I Normal Occlusion
Variable
Constant
Linear
(rate)
Quadratic
Class II, Division 2
Cubic
Constant
Linear
(rate)
Quadratic
Cubic
45
SNA
80.98
0.00031
0.03047
-0.00277
81.81
0.06022
0.007945
-0.00165
SNB
77.32
0.1867
0.02108
-0.00275
77.45
-0.0304
0.003472
-0.00165
ANB
3.742
-0.1432
4.46
0.03688
Y-Axis
67.23
SN-GoGn(MPA)
33.36
-0.2494
30.43
-0.1493
PP-MP
26.36
-0.409
23.53
-0.0596
Gonial angle
120.4
-0.1004
118.33
-0.1651
PP angle
7.086
0.212
6.98
-0.1015
Ba-S-N
129.9
127.88
ANSPNSp
72.99
73.41
PAFHp
63.25
0.3344
GoGnp
99.71
1.171
MxMdp
74.14
-0.348
U1-L1
130.4
-0.8837
0.3791
U1-SN
101.9
0.495
IMPA
93.16
L6L1p
74.38
66.28
-0.01082
65.95
0.1347
100.06
0.00758
74.31
-0.0427
-0.02802
136.22
-0.2121
0.01619
0.6166
-0.1171
-0.1275
0.1896
-0.00655
-0.00563
0.0012
-0.00614
-0.00078
0.3345
0.05097
-0.00941
98.17
-0.397
0.06603
-0.00002
0.006289
93.51
0.0444
-0.1394
0.01463
-0.01514
74.98
-0.033
0.0118
-0.00443
Bold numbers indicate statistically significant (p<0.05) group differences
Growth Curves of Variables Showing Significant Differences
The mandibular and the palatal to mandibular plane
angles decreased significantly between 6-19 years of age
(Figure 3.3), with Class II, Division 2 subjects having
smaller angles than Class I's throughout childhood and
adolescence. The differences in the mandibular plane angle
increased from 2.3 degrees at 6-7 years to 4.1 degrees at
18-19 years.
The PP-MP angles were approximately 2.6
degrees smaller in Class II, Division 2 subjects initially,
and remained approximately that much smaller throughout the
age ranges.
The palatal plane angles for both groups were similar
between 6-10 years of age, after which the angle increased
more for Class I subjects than for Class II, Division 2
subjects. The cranial base angle (Ba-S-N) was significantly
(2.0 degrees) smaller in Class II‟s from 6 to 19 years of
age (Figure 3.3).
46
47
Figure 3.3. Variables showing significant differences between Class I and Class II, Division 2 subjects
The posterior to anterior facial height proportion
(PAFHp) was initially 2.2% larger in Class II, Division 2
subjects, and the differences increased to 3.8% at 18-19
years of (Figure 3.4). The interincisal angle (U1-L1)
decreased rapidly in both groups between 6-10 years of age,
remained relatively stable through 13 years, and then
increased through adulthood. Class II, Division 2 subjects
had larger interincisal angles throughout; the initial 5.9
deg. difference increased to 7.0 degrees at 18-19 years of
age. Following the inverse pattern, the U1-SN angle
increased initially and then decreased during adolescence
and early adulthood. It was smaller in Class II, Division 2
subjects throughout the study period. The difference was
4.3 degrees at 12-13 years and decreased to 2.7 at 18-19
years of age (Figure 3.4).
The gonial angle (Ar-Go-Gn) decreased over time in
both groups, with slightly larger decreases among Class II,
Division 2 than Class I subjects.
Differences increased
from 1.4 degrees at 6-7 years to 3.4 degrees at 18-19 years
(Figure 3.4).
48
49
Figure 3.4. Variables showing significant differences between Class I and Class II, Division 2 subjects
Growth Curves of Variables Showing No Group Differences
The SNA, SNB, ANB angles, the Y axis (Figure 3.5) and
maxillary proportion – ANSPNSp - (Figure 3.6) showed small
or no changes between 6-19 years of age. Although none of
the differences were statistically significant, the SNA and
ANB angles were slightly larger (≈0.8 deg) in Class II,
Division 2 than Class I subjects; while the Y axis was
slightly smaller (≈0.9 deg); the SNB angle and ANSPNSp
showed similar values in both groups.
The relative sizes of the maxilla and mandible (MxMdp)
decreased from 75% at 6-7 years to 71% at 18-19 years in
both groups, and the mandibular proportion (GoGnp)
increased consistently between 6-19 years of age (Figure
3.6).
The relative height of the first mandibular molar to
the mandibular incisor (L6L1p) decreased approximately 5%
between 6-10 years of age, and then increases slightly (≈23%) between 10-19 years (Figure 3.7).
IMPA, which was initially smaller for Class II,
Division 2 subjects, increased 5-8 degrees between 6-10
years of age, and then remained at 93-94 degrees between
10-16 years of age for both groups (Figure 3.7).
50
51
Figure 3.5. Variables showing non-significant differences between Class I and Class II, Division 2 subjects
52
Figure 3.6. Variables showing non-significant differences between Class I and Class II, Division 2 subjects
53
Figure 3.7. Variables showing non-significant differences between Class I and Class II, Division 2
subjects
Discussion
Differences between individuals with Class II,
Division 2 and Class I normal occlusions were already
largely developed at the earliest ages. At 6 years of age,
the subjects with Class II, Division 2 malocclusion already
exhibited hypodivergent growth patterns, relatively greater
posterior facial heights, more acute cranial base angles,
greater interincisal angles, and upright incisors. This
suggests that the etiology of Class II, Division 2
malocclusion has a genetic component. Peck et al.12
described smaller than average mesio-distal tooth diameters
among Class II division 2 subjects, while Beresford10 and
Roberston and Hilton,31 found these teeth to be
significantly „thinner‟ teeth measured in the
labial/lingual dimension. Familial occurrence of Class II,
Division 2 has been documented in twin and triplet studies
and in family pedigrees.12-14 These studies point to strong
genetic influence, probably autosomal dominant with
incomplete penetrance and simultaneous expression of a
number of genes (acting additively), rather than being the
effect of a single controlling gene for the entire
malocclusion.
54
Class II, Division 2 subjects were more hypodivergent
than Class I subjects. The ratio between posterior and
anterior facial heights increased significantly faster
among Class II, Division 2‟s, probably due to relatively
smaller increases in anterior than posterior facial
heights. Previous studies evaluating vertical
dimensions16,17,20,23-25,32,33 suggest that there is a relative
underdevelopment of anterior lower facial heights among
Class II, Division 2 subjects. Posterior heights have
either been reported to be excessive among Class II,
Division 2 cases,33 or not different.22,23 Class II, Division
2 subjects appear to be undergoing greater forward
mandibular rotation than Class I subjects, even at the
younger ages.
Because Class II, Division 2 subjects are
hypodivergent, the mandibular plane angles, palatal plane
to mandibular plane angles, and gonial angles were all
smaller than in Class I subjects. Numerous cross-sectional
studies have reported similar differences.12,17,20,21,23-25,32,33
The mandibular plane and palatal plane angles showed
significantly greater decreases in Class II‟s, indicating
that their hypodivergence worsens over time.
55
Interestingly, Class II, Division 2 subjects also
have smaller cranial base angles than Class I subjects
throughout childhood, adolescence, and early adulthood.
This finding also suggests that the etiology of Class II,
Division 2 malocclusion has a genetic component. Others
have reported larger cranial base angles among Class II,
Division 2 subjects,23 or cranial base angles that were
similar to Class I‟s.20
A smaller cranial base angle might
be expected to reposition the mandible more anteriorly.
Assuming Class II, Division 2 subjects undergo greater
amounts of forward mandibular rotation, as suggested by
their greater hypodivergence, and greater forward rotation
is related to greater condylar growth in a more anterior
direction,34 then the effects of a smaller cranial base
angle could be negated. In other words, if a smaller angle
for cranial base tends to position the mandible in a more
anterior position, the incremental growth at the condyle
could counterbalance this tendency if the direction of
growth at the condyle is oriented more anteriorly. This
change in direction of condylar growth could be the reason
for the mandible being in a more normal position and for
the increased posterior facial heights of Class II,
Division 2 subjects.
56
A smaller cranial base angle and greater forward
rotation among Class II, Division 2 subjects could be
responsible for locking the mandibular dentition behind the
anterior portion of the palate.35-38 This would be consistent
with the lack of anterior facial height development
observed among Class II, Division 2 individuals. The notion
of a “locked” mandible is based mostly in clinical
observations, but it is reasonable and holds important
clinical implications. If treatment can be started before
growth stops, allowing the mandible to grow in a more
forward direction, it might be expected that the Class II,
Division 2 mandibles develop similarly to Class I‟s.28
Subjects with Class II, Division 2 malocclusion also
have upright maxillary incisors and normal positioned
mandibular incisors. These dental characteristics have been
previously ascribed to Class II, Division 2 subjects, with
multiple studies showing significantly larger interincisal
angles (U1-L1) and smaller U1-SN angles.16,18,19,22,23,25,26 The
findings of this study support previous findings, and
extend them by showing that the upright position of upper
incisors is already present in Class II, Division 2
subjects during childhood.
57
Relative to the size of the anterior cranial base, the
maxillas and mandibles of Class II, Division 2 subjects
were similar to those of Class I‟s.
Previous studies17-19,39
have also concluded that individuals with Class II,
Division 2 malocclusion are skeletally similar to Class I‟s
(i.e., that there is no underdevelopment of the mandibular
basal bone). Other studies16,20-23 however, have found smaller
mandibles among Class II, Division 2 subjects. It is
important to emphasize that the present study evaluated the
size of the jaws relative to the size of the anterior
cranial base (S-N). This is important because some studies
have reported similar cranial base sizes among Class II,
Division 2 and Class I subjects,19,22 while others have found
larger cranial bases.23,24 Proportional measurements make it
possible to make comparisons independent of possible size
differences.
The relative dento-alveolar heights in the mandibular
molar and incisor regions are also similar for Class I and
Class II, Division 2 subjects. The ratio between the
heights of the mandibular 1st molar and mandibular central
incisor perpendicular to the mandibular plane (L6L1p)
remained similar throughout the study period for both
groups. Strang40 and Karlsen16 reported reduced dento-
58
alveolar heights in the molar area, but Strang did not
measure it, he just observed it clinically. It might be
expected that reduced dento-alveolar heights in the
mandibular molar regions would add to a decrease in lower
anterior facial height in Class II, Division 2 subjects,
and over-erupted lower incisors would worsen the deep bite
pattern, but this study did not find such differences
between Class I‟s and Class II, Division 2 subjects. This
suggests that the deeper bite attributed to Class II,
Division 2 subjects16,19,20,25,25,41 is primarily due to overrotation rather than overeruption.
The anteroposterior positions of the maxilla and
mandible were also similar for Class I and Class II,
Division 2 subjects.
The present study showed similar ANB,
SNA and SNB angles for both groups. While some studies
support the idea that the mandible and maxilla are normally
positioned in Class II, Division 2 subjects,17,22,27 others
have found that the maxilla is positioned forward,18,25,32 and
even more have found that the mandible is retropositioned20,21,23,24,26,32 in Class II, Division 2 subjects
compared to Class I‟s. Based on the present study, it can
be inferred that Class II, Division 2 and Class I subjects
present similar anteroposterior skeletal relationships
59
(i.e., that there is no underdevelopment of the mandibular
basal bone) and the mandibular dental arch may become
retro-positioned and “locked” behind the anterior portion
of the maxilla during the development of the malocclusion.
This would also be consistent with the hypodivergent growth
pattern of Class II, Division 2 subjects playing a role.
60
Conclusions
According to the results of this study, untreated
Class II, Division 2 subjects 6-19 years of age present
with the following characteristics:
1) Maxillas and mandibles of normal size and in
similar anteroposterior positions as in Class I subjects
with normal occlusion.
2) Hypodivergent growth pattern, with smaller
mandibular plane angles, palatal plane to mandibular plane
angles and gonial angles.
3) The proportion between anterior and posterior
facial heights is increased, suggesting that there is a
relative greater increase in posterior than anterior facial
height.
4) Proportionate dento-alveolar heights of the
mandibular molar and incisor regions that are similar to
Class I subjects.
5) More acute cranial base (Ba-S-N) angles.
6) Upright maxillary incisors and mandibular incisors
that are slightly retroclined when compared to Class I
subjects.
61
7) Differences between individuals with Class II,
Division 2 and Class I normal occlusions are already
evident at 6 years of age and the measurements related to
the hypodivergent growth pattern and incisal relationship
become worse over time.
62
References
1.
Massler M, Frankel JM. Prevalence of malocclusion in
children aged 14 to 18 years. Am J Orthod. 1951
Oct;37(10):751–68.
2.
Ast DB, Carlos JP, Cons NC. The prevalence and
characteristics of malocclusion among senior high school
students in upstate New York. Am J Orthod. 1965
Jun;51:437–45.
3.
Mills LF. Epidemiologic studies of occlusion. IV. The
prevalence of malocclusion in a population of 1,455
school children. J Dent Res. 1966 Apr;45(2):332–6.
4.
Proffit WR, Fields HW Jr, Moray LJ. Prevalence of
malocclusion and orthodontic treatment need in the
United States: estimates from the NHANES III survey. Int
J Adult Orthodon Orthognath Surg. 1998;13(2):97–106.
5.
da Silva Filho OG, de Freitas SF, Cavassan A de O.
[Prevalence of normal occlusion and malocclusion in
Bauru (Sao Paulo) students. 1. Sagittal relation]. Rev
Odontol Univ Sao Paulo. 1990 Jun;4(2):130–7.
6.
Altemus, L. Frequency of the incidence of malocclusion
in American Negro children aged twelve to sixteen. Angle
Orthod. 1959 Oct;29(4):189–200.
7.
Zilberman S, Kawar,. Prevalence and severity of
malocclusion in Israeli Arab urban children - 13 to 15
years of age. Am J Orthod. 1983;84(4):337–43.
8.
Perng C, Lin J. Preliminary study of malocclusion of
pedodontic patients in Veterans General Hospital. Taiwan
Clin Dent. 1983;3:19–26.
9.
Proffit WR. Contemporary Orthodontics. 4th ed. Saint
Louis, MO: Mosby / Elsevier; 2007.
10. Beresford J. Tooth size and class distinction. Dent
Pract. 1969;20:113–20.
11. Robertson NR, Hilton R. Feature of the upper central
incisors in Class II Division 2. Angle Orthod. 1965
Jan;35:51–3.
63
12.
Peck S, Peck L, Kataja M. Class II Division 2
malocclusion: a heritable pattern of small teeth in
well-developed jaws. Angle Orthod. 1998 Feb;68(1):9–20.
13.
Markovic MD. At the cross-roads of orofacial genetics.
Eur J Orthod. 1992;14:469–81.
14.
Mossey PA. The heritability of malocclusion: part 2.
The influence of genetics in malocclusion. Br J Orthod.
1999 Sep;26(3):195–203.
15.
Angle E. Treatments of Malocclusion of the Teeth. 7th
ed. Philadelphia: S.S. White Dent. Mfg. Co.; 1907.
16.
Karlsen AT. Craniofacial characteristics in children
with Angle Class II div. 2 malocclusion combined with
extreme deep bite. Angle Orthod. 1994;64(2):123–30.
17.
Isik F, Nalbantgil D, Sayinsu K, Arun T. A comparative
study of cephalometric and arch width characteristics of
Class II division 1 and division 2 malocclusions. Eur J
Orthod. 2006 Apr;28(2):179–83.
18.
Renfroe E. A study of the facial patterns associated
with Class I, Class II, Division 1, and Class II,
Division 2 malocclusions. Angle Orthod. 1948;18:12–5.
19.
Fischer-Brandies H, Fischer-Brandies E, König A. A
cephalometric comparison between Angle Class II,
division 2 malocclusion and normal occlusion in adults.
Br J Orthod. 1985 Jul;12(3):158–62.
20.
Brezniak N, Arad A, Heller M, Dinbar A, Dinte A,
Wasserstein A. Pathognomonic cephalometric
characteristics of Angle Class II Division 2
malocclusion. Angle Orthod. 2002 Jun;72(3):251–7.
21.
Blair ES. A Cephalometric roentgenographic appraisal
of the skeletal morphology of Class I, Class II, Div. 1,
and Class II, Div. 2 (Angle) malocclusions. Angle
Orthod. 1954;24:106–19.
22.
Godiawala RN, Joshi MR. A cephalometric comparison
between Class II, division 2 malocclusion and normal
occlusion. Angle Orthod. 1974 Jul;44(3):262–7.
64
23.
Wallis S. Integration of certain variants of the
facial skeleton in Class II, division 2 malocclusion.
Angle Orthod. 1963 Jan;33(1):60–7.
24.
Houston WJ. A cephalometric analysis of Angle Class
II, division II malocclusion in the mixed dentition.
Dent Pract Dent Rec. 1967 Jun;17(10):372–6.
25.
Al-Khateeb EAA, Al-Khateeb SN. Anteroposterior and
vertical components of Class II division 1 and division
2 malocclusion. Angle Orthod. 2009 Sep;79(5):859–66.
26.
Hitchcock HP. The cephalometric distinction of Class
II, division 2 malocclusion. Am J Orthod. 1976
Apr;69(4):447–54.
27.
Balridge JP. A Study of the relation of the maxillary
first permanent molars to the face in Class I and Class
II malocclusions. Angle Orthod. 1941 Apr;11(2):100–9.
28.
Lovell D. Longitudinal growth evaluation of treated
and untreated Angle Class II, Division 2 malocclusions.
Thesis - CADE, Saint Louis University 2011; pg 34.
29.
Buschang PH, Tanguay R, Turkewicz J, Demirjian A, La
Palme L. A polynomial approach to craniofacial growth:
description and comparison of adolescent males with
normal occlusion and those with untreated Class II
malocclusion. Am J Orthod Dentofacial Orthop. 1986
Nov;90(5):437–42.
30.
Chvatal BA, Behrents RG, Ceen RF, Buschang PH.
Development and testing of multilevel models for
longitudinal craniofacial growth prediction. Am J Orthod
Dentofacial Orthop. 2005 Jul;128(1):45–56.
31.
Robertson NR, Hilton R. Feature of the upper central
incisors in Class II, Division 2. Angle Orthod. 1965
Jan;35:51–3.
32.
Pancherz H, Zieber K, Hoyer B. Cephalometric
characteristics of Class II division 1 and Class II
division 2 malocclusions: a comparative study in
children. Angle Orthod. 1997;67(2):111–20.
33.
Maj G, Lucchese FP. The mandible in Class II, Division
2. Angle Orthod. 1982 Oct;52(4):288–92.
65
34.
Dibbets JM. Mandibular rotation and enlargement. Am J
Orthod Dentofacial Orthop. 1990 Jul;98(1):29–32.
35.
Ricketts R, Bench R, Gugino C, Hilgers J, Schulhof R.
Bioprogressive Therapy. Denver: Rocky Mt. Orthod. 1979.
36.
Taylor A. Release mechanisms in the treatment of Class
II, Division 2 malocclusions. Aust Dent. J. 1966;11:27–
37.
37.
Arvystas M. Treatment of severe mandibular retrusion
in Class II, Division 2 malocclusion. Am J Orthod.
1979;76(2):149–64.
38.
Levy P. Growth of the mandible after correction of the
Class II, Division 2 malocclusion. Proceed Found Ortho
Research., Dept. of Orthodontics, UCLA School of
Dentistry. 1979;
39.
Cleall JF, BeGole EA. Diagnosis and treatment of Class
II, Division 2 malocclusion. Angle Orthod. 1982
Jan;52(1):38–60.
40.
Strang R. Class II, Division 2 Malocclusion. Angle
Orthod. 1958 Oct;28(4):210–4.
41.
Eastern Component Group. A clinical study of cases of
malocclusion in Class II, Division 2. Angle Orthod.
1935;5:87–106.
66
APPENDIX
Table A.1 - CLASS I
Time points →
67
Class I
SNA
SNB
ANB
Y-Axis
MP (GoGn-SN)
PP-MP
Ar-Go-Gn
PP (ANSPNS-SN)
Ba-S-N
U1-L1
U1-SN
IMPA
ANSPNS (%)
GoGn (%)
Mx:Md (%)
PAFH (%)
L6:L1 (%)
(Descriptive – Changes over time)
Growth Changes Over Time (Angular and Proportional measurements)
T1-T2
T2-T3
T3-T4
T4-T5
Mean
SD
Mean
SD
Mean
SD
Mean
SD
-0.7
-0.2
-0.6
0.0
-0.8
-2.0
-0.2
1.2
-0.1
-9.0
5.4
3.9
0.3
3.5
-1.5
0.4
-3.4
1.3
1.3
1.5
1.2
1.8
2.0
3.7
1.1
2.2
10.5
5.0
5.6
3.7
3.1
3.6
2.0
4.7
0.3
0.5
-0.2
0.1
-0.4
-0.9
0.1
0.5
-0.2
0.6
-1.3
1.3
-0.2
3.2
-1.8
0.5
0.3
1.1
1.1
1.1
1.3
2.2
2.2
4.7
1.4
2.3
5.4
4.1
4.1
3.1
1.9
2.9
1.7
2.5
Bold numbers indicate statistically significant differences
0.1
0.5
-0.5
0.3
-1.0
-1.3
0.5
0.4
0.1
1.2
0.1
-0.4
1.2
2.8
-0.5
1.4
1.9
1.0
0.9
0.9
0.8
1.5
1.5
2.2
1.1
2.4
5.6
3.3
4.2
2.8
2.1
2.7
1.4
1.8
0.1
0.4
-0.2
-0.2
-0.5
-0.4
-1.0
-0.1
-0.2
1.2
-0.3
-0.4
0.1
0.3
-0.1
0.9
0.9
1.1
0.9
0.7
0.9
1.1
1.0
1.8
0.9
1.6
3.0
2.5
2.4
1.5
1.8
1.5
1.0
2.8
T1-T5
Mean
SD
0.3
1.7
-1.4
-0.1
-3.5
-5.5
-4.6
1.9
-0.5
-6.8
4.6
5.6
-3.9
8.2
-3.8
4.5
1.4
2.7
2.1
1.5
1.4
3.2
3.2
4.9
2.3
3.2
9.0
5.2
6.5
3.4
3.9
3.4
2.9
5.5
Table A.2 - CLASS II DIV. 2
Time points →
68
Class II
Div. 2
SNA
SNB
ANB
Y-Axis
MP (GoGn-SN)
PP-MP
Ar-Go-Gn
PP (ANSPNS-SN)
Ba-S-N
U1-L1
U1-SN
IMPA
ANSPNS (%)
GoGn (%)
Mx:Md (%)
PAFH (%)
L6:L1 (%)
(Descriptive – Changes over time)
Growth Changes Over Time (Angular and Proportional measurements)
T1-T2
T2-T3
T3-T4
T4-T5
Mean
SD
Mean
SD
Mean
SD
Mean
SD
-0.5
0.0
-0.5
0.2
-1.2
-1.4
-1.0
0.2
-0.7
-10.6
3.3
7.3
-0.1
4.1
-1.9
1.1
-3.5
1.2
0.9
1.2
0.9
2.0
2.7
3.6
1.7
2.1
9.2
7.2
5.4
3.6
1.7
3.3
1.9
6.1
0.4
0.8
-0.3
-0.4
-1.3
-1.6
-1.0
0.3
0.1
3.3
-1.9
-0.7
0.4
2.8
-1.1
1.5
-0.7
1.0
1.0
1.2
1.1
1.5
1.9
2.6
1.2
1.9
6.8
5.4
3.4
2.7
1.5
2.3
1.5
4.3
Bold numbers indicate statistically significant differences
0.2
0.5
-0.3
0.0
-1.3
-1.3
-0.3
0.0
0.1
0.1
0.6
0.9
0.5
2.7
-0.8
1.8
2.5
1.3
1.2
1.0
1.1
2.0
2.3
3.2
2.3
1.7
9.8
6.2
4.8
2.8
2.3
2.5
2.1
3.1
-0.1
0.1
-0.2
0.0
-0.6
-0.9
-0.5
0.2
0.2
1.9
-0.1
-1.1
-0.6
0.7
-0.8
0.6
-1.5
1.3
0.7
0.9
0.8
1.1
1.2
1.8
0.8
1.6
4.5
3.3
3.1
2.2
2.3
2.4
1.5
3.7
T1-T5
Mean
SD
0.1
1.9
-1.8
-0.6
-4.3
-4.1
-5.7
-0.2
-0.4
-10.5
6.3
8.7
-6.4
9.3
-6.4
4.8
3.9
1.2
1.3
1.1
1.0
2.7
4.1
4.6
2.9
3.5
12.7
10.7
4.7
4.8
2.0
4.9
2.5
8.0
VITA AUCTORIS
Luiz Alexandre Guerino Barbosa was born on October
14th, 1972 in Brasilia, DF, Brazil to Jose Luiz Barbosa and
Maria Ruth Guerino Barbosa. He is the first of four
children.
He was raised in Brasilia, the capital of Brazil and
graduated from high school at Sao Paulo Adventist Institute
(IASP) in Campinas, SP in 1989. After high school, Dr.
Barbosa began his dental training at University of Ribeirao
Preto Dental School where he received his D.D.S. (Doctor of
Dental Science) in 1995. Dr. Barbosa worked in private
practice as a general dentist for 13 years in Brasilia,
Brazil. He started his orthodontic training at Sao Paulo
State University (UNESP) in 2006 and received his
Certificate in Orthodontics in 2008. Seeking for more
knowledge and following his dreams to experience life in
another country, Dr. Barbosa moved to the U.S. with his
family to start his orthodontic residency at Saint Louis
University in June 2009.
Dr. Barbosa expects to receive a Master of Science in
Dentistry (Research) degree from Saint Louis University in
August 2012. He plans on practicing orthodontics in
Florida.
69