Download POST-TREATMENT EVALUATION OF MAXILLARY CANINE POSITION John Katsis III, D.D.S.

POST-TREATMENT EVALUATION OF MAXILLARY CANINE POSITION
IN ADOLESCENT CAUCASIAN MALES AND FEMALES
John Katsis III, 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
2012
Abstract
Introduction: Esthetic improvement is one of the primary
reasons individuals seek orthodontic treatment.
The
maxillary canine is considered by many to have great
importance for both function and esthetics.
Limited
information is available about the position of the
maxillary canine in relation to skeletal landmarks and if
the position can influence esthetic perception.
Purpose:
The purpose of this study was to evaluate the normal
maxillary canine position in relation to skeletal
landmarks, to determine post-treatment three-dimensional
maxillary canine position with Cone Beam CT images, and to
see if maxillary canine position could influence esthetic
perception.
Methods: The Bolton Standard template acted as
the control sample and the maxillary canine position was
determined by implementing a Cartesian coordinate system.
The right and left maxillary canines of 48 males and 48
females who received orthodontic treatment were analyzed by
digitization of Cone Beam CT volumes.
The subject’s post-
treatment smile photographs were ranked and quantified by
nine orthodontic residents who completed a Q-sort.
Correlations were determined between canine position and
esthetic outcomes. Results: The only difference between
1
right and left canine position was the anterior-posterior
position of the root apex.
Statistically significant
gender differences were found for the superior-inferior
position of the right and left canine cusp tip, the mediallateral right and left canine root apex, and the mediallateral left canine cusp tip.
No correlation was
determined between the maxillary canine position and
esthetic perception.
Conclusion: The maxillary canine
position in relation to skeletal landmarks was determined
and does not appear to significantly impact esthetic
perception according to this study.
2
POST-TREATMENT EVALUATION OF MAXILLARY CANINE POSITION
IN ADOLESCENT CAUCASIAN MALES AND FEMALES
John Katsis III, 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
2012
COMMITTEE IN CHARGE OF CANDIDACY:
Professor Rolf G. Behrents,
Chairperson and Advisor
Professor Eustaquio A. Araujo
Associate Clinical Professor Donald R. Oliver
Associate Clinical Professor Ki Beom Kim
i
DEDICATION
I dedicate this thesis to my parents. Throughout my
life they have served as a source of inspiration on how to
live a life of integrity, dedication, and commitment.
I
also would like to dedicate this to my siblings who have
provided unwavering support in all my endeavors.
ii
ACKNOWLEDGEMENTS
I would like to acknowledge the following individuals:

Dr. Behrents for his mentorship and dedication to this
project.
I would not have been able to complete this
project without him.

Dr. Oliver for his support and help with the stylistic
portion of writing my thesis.
He was willing and
eager to help at any time.

Dr. Araujo for his creative input to the project.
He
is a wealth of knowledge and an excellent role model
on how to lead a life of many passions.

Dr. Ki Beom Kim for his help with the technological
aspects of the project.
His help was invaluable to
the completion of the project.

Dr. Heidi Israel for her help with the statistical
analysis of the project.
I would also like to thank my co-residents for their
assistance and support while working on my thesis and
throughout my entire residency.
iii
TABLE OF CONTENTS
List of Tables...........................................vi
List of Figures.........................................vii
CHAPTER 1: INTRODUCTION...................................1
CHAPTER 2: REVIEW OF THE LITERATURE.......................3
Facial Esthetics in Orthodontics.....................3
Dental Esthetics in Orthodontics.....................4
Smile Esthetics in Orthodontics......................7
Tooth Morphology and Esthetic Perception.............9
Quantification of Esthetic Outcomes.................10
Quantification of Skeletal and
Dental Relationships... .......................13
Advancements in Orthodontic Treatment...............14
Functional Importance of the Maxillary Canine.......16
Maxillary Canine Positional Characteristics in
Relation to the Dental Arch....................18
Maxillary Canine Position in Relation to
Soft-Tissue landmarks..........................20
Maxillary Canine Position in Relation to
Skeletal Landmarks.............................21
Summary and Statement of Purpose....................25
References..........................................26
CHAPTER 3: JOURNAL ARTICLE
Abstract............................................30
Introduction........................................32
Materials and Methods...............................36
Control Sample.................................36
Orientation of Control Sample..................36
Control Sample Cephalometric Landmarks.........38
Experimental Sample............................41
Orientation of Experimental
Sample CBCT Volumes.......................41
Measurement Methods of Experimental Sample.....43
Establishing Data Points.......................43
Determination of Canine Angulation and
Position..................................44
Q-sort.........................................45
Statistics.....................................47
Results.............................................50
Error Study....................................50
Control Sample Results.........................50
iv
Descriptive Statistics of
Experimental Sample.......................52
Scatter Plot Data..............................56
Maxillary Canine Position Patterns.............61
Esthetic Results...............................63
Esthetic Results in Relation to
Canine Position...........................64
Discussion..........................................69
Three Dimensional Assessment of
Maxillary Canine Position.................69
Maxillary Canine Position and
Esthetic Perception.......................71
Conclusion..........................................74
Literature Cited....................................75
Appendix A (Histograms of linear distances
from control sample)......................78
Appendix B (Graphs of best and worst esthetic
Outcome XY and YZ canine position)........81
Appendix C (Photographs of subjects with highest
and lowest combined esthetic scores)......82
Appendix D (Photographs of subjects with highest
and lowest total canine position scores)..84
Vita Auctoris............................................86
v
LIST OF TABLES
Table 3.1: Cephalometric landmarks of control
sample........................................39
Table 3.2: Bolton standard Cartesian coordinates.........51
Table 3.3: Bolton standard Cartesian coordinates.........51
Table 3.4: Bolton standard angular measurements..........51
Table 3.5: Descriptive statistics digitized landmarks
of experimental sample........................52
Table 3.6: Descriptive statistics of angular
measurements of experimental sample...........53
Table 3.7: Comparison of gender differences in
experimental sample...........................54
Table 3.8: Comparison of right and left maxillary canine
position in experimental sample...............55
Table 3.9: Correlations of esthetic scores and maxillary
canine position scores........................67
vi
LIST OF FIGURES
Figure 2.1: Relationship of contact points,
connectors, and embrasures...................6
Figure 2.2: Simon’s Facebow and Gnathostat
devices......................................23
Figure 2.3: Simon’s Photostat device.....................24
Figure 3.1: Orientation of the PA tracing................37
Figure 3.2: Orientation of the lateral
tracing......................................38
Figure 3.3: Cephalometric landmarks of PA
tracing......................................40
Figure 3.4: Cephalometric landmarks of lateral
tracing......................................40
Figure 3.5: Orientation of the CBCT volume...............42
Figure 3.6: Digitization of maxillary canine cusp tip
and root apex................................44
Figure 3.7: Example of smile photograph..................46
Figure 3.8: Scatter plot of XY axis of right canine
cusp tip.....................................56
Figure 3.9: Scatter plot of XY axis of right canine
root apex....................................57
Figure 3.10: Scatter plot of ZY axis of right canine
cusp tip....................................58
Figure 3.11: Scatter plot of ZY axis of right canine
root apex...................................59
Figure 3.12: Scatter plot of XZ axis of right canine
cusp tip....................................60
Figure 3.13: Scatter plot of XZ axis of right canine
root apex...................................61
Figure 3.14: Histogram of esthetic Q-sort result.........63
vii
Figure 3.15: Graph and correlation of esthetic
scores vs. total canine position............65
Figure 3.16: Graph and correlation of esthetic
scores vs. XY axis canine position..........65
Figure 3.17: Graph and correlation of esthetic
scores vs. ZY axis canine position..........66
Figure 3.18: Graph and correlation of esthetic
scores vs. XZ axis canine position..........66
Figure 3.19: Graph and correlation of total canine
position scores vs. esthetic scores.........67
Figure 3.20: Histogram of linear distance from the
norm of right canine cusp of the XY axis....78
Figure 3.21: Histogram of linear distance from the
norm of right canine apex of the XY axis....78
Figure 3.22: Histogram of linear distance from the
norm of right canine cusp of the ZY axis....79
Figure 3.23: Histogram of linear distance from the
norm of right canine apex of the ZY axis....79
Figure 3.24: Histogram of linear distance from the
norm of right canine cusp of the XZ axis....80
Figure 3.25: Histogram of linear distance from the
norm of right canine apex of the XY axis....80
Figure 3.26: Graph of XY canine position of
four best and four worst esthetic
outcomes compared to Bolton Standard........81
Figure 3.27: Graph of ZY canine position of
four best and four worst esthetic
outcomes compared to Bolton Standard........81
Figure 3.28: Smile photographs of four subjects
with highest combined esthetic scores.......82
Figure 3.29: Smile photographs of four subjects
with lowest combined esthetic scores........83
viii
Figure 3.30: Smile photographs of four subjects with
highest combined canine position scores.....84
Figure 3.31: Smile photographs of four subjects with
lowest combined canine position scores......85
ix
CHAPTER 1: INTRODUCTION
The improvement of facial and dental esthetics is one
of the primary reasons individuals seek orthodontic
treatment.
Advancements in orthodontic treatment such as
orthognathic surgery and temporary anchorage devices allow
a clinician to effectively manipulate the dentition in
three planes of space.
The question arises as to where the
teeth should be placed in order to maximize esthetics.
Orthodontists have utilized a variety of diagnostic and
treatment planning methods to achieve this.
One such
method developed by Simon, a German orthodontist in the
early 20th century, utilized a facebow and articulator
device to recreate the skeletal and dental relationship.1 He
believed that individuals with normal relationships had the
maxillary canine crown positioned along the orbital plane,
defined as a frontal plane perpendicular to the midsagittal and the Frankfort horizontal planes.2 Other studies
have examined the relationship of the canine to the orbital
plane with conflicting results.2,3 Technological
advancements, such as three-dimensional imaging, allow the
orthodontist to accurately examine dental and skeletal
relationships in three dimensions.
1
The purpose of this
study is threefold.
First, the normal maxillary canine
position in relation to skeletal landmarks will be
determined.
Second, a post-treatment three-dimensional
assessment of maxillary canine position utilizing CBCT
volumes of Caucasian male and female subjects will be
completed.
Finally, the effect of the maxillary canine
position on esthetic perception of frontal smiling
photographs will be determined.
2
CHAPTER 2: REVIEW OF THE LITERATURE
Facial Esthetics in Orthodontics
Orthodontics is often referred to as an art and a
science.
The “art” portion of orthodontics is due to the
fact that the clinician has the ability and responsibility
to shape the dentition and surrounding tissues to create
the most visually pleasing result possible.
Although the
orthodontic literature has a vast amount of information
about esthetics that dates back over a century, a
universal, objective way to define beauty on an individual
basis may not be possible.
The perception of facial
esthetics has cultural, genetic, and sexual influences that
vary significantly among individuals.4–6
Because of the
subjective nature of esthetic judgment the evaluation of
facial esthetics focuses primarily on symmetry and facial
proportions.7
Even though esthetic preferences vary significantly
among individuals, facial symmetry has been shown to
routinely be positively correlated to esthetic perception.
Facial symmetry is defined as the extent to which one side
of the face mirrors the opposite side when divided
vertically at the facial midline.5
3
Jones showed that
individuals with high levels of facial symmetry were
perceived to be more attractive and increased facial
symmetry was also positively correlated with the perception
of good health.6
In Little’s review of facial
attractiveness, facial symmetry had positive correlations
with growth rate, attractiveness, and fertility.5
The
attainment of facial symmetry is an important consideration
in orthodontic diagnosis and treatment planning.
Dental Esthetics in Orthodontics
In order to maximize smile esthetics, one must have a
thorough understanding of dental esthetics.
The shape and
contour of the teeth has a great impact on dental
esthetics.
The maxillary central incisors should ideally
have a width to height ratio of 0.8 with ranges reported in
the literature between 0.66-0.8.8
Variations in this ratio
can be due to reduced tooth mass, incomplete eruption, or
aberrant gingival architecture.
The position of the maxillary anterior teeth is
important for smile esthetics.
The dental midline
relationship, symmetry, contact relationships, and tooth
angulation all affect dental esthetics.
4
The dental midline
is represented by the contact of the left and right
maxillary central incisors.
The dental midline should be
coincident with soft tissue nasion and the base of the
philtrum of the upper lip.9
The contact point of the
mandibular central incisors should also be coincident with
the maxillary dental midline.
Dental symmetry is similar
to facial symmetry in that it is determined by the extent
the left and right maxillary anterior teeth mirror each
other.
The contact point among the maxillary teeth
progressively moves more apically as the teeth move
distally along the arch.
The perceived contact area, also
referred to as the connector, between the maxillary teeth
diminishes moving from the midline to the distal portion of
the arch.
Dental embrasures are defined as the negative
spaces incisal to the contact points of teeth.
The incisal
embrasure of the maxillary anterior teeth is the smallest
at the dental midline between the right and left maxillary
central incisor and should appear to grow larger moving
distally through the arch.8
The contact and embrasure
relationship of the teeth is influenced by the angulation
of the tooth.
According to Andrews, the maxillary anterior
teeth should also exhibit a slight distal tip of the
gingival portion of the crown when compared to the incisal
portion.10
5
Figure 2.1: Relationship of contact points, connectors, and
embrasures modified from Sarver.11
The gingival tissues framing the teeth play an
important role in dental esthetics as well.
The gingiva
dictates the cervical shape of each tooth. In the absence
of periodontal disease, the shape of the gingiva follows
the cementoenamel junction and osseous crest.
For an
individual tooth the gingiva is shaped like an asymmetric
arch with the apex of the arch slightly distal to the
central axis of the tooth in the maxillary central incisors
and maxillary canines.
The apex of the gingiva in the
maxillary laterals and mandibular incisors follows the long
axis of the tooth.8,11 The gingival margins of the maxillary
anterior teeth follow a “high-low-high” pattern in that the
gingival margins of the maxillary central incisors and
6
canines have a more superior position when compared to the
maxillary lateral incisors.8,9,11
Smile Esthetics in Orthodontics
The position of the teeth within the mouth plays a
significant role in the appearance of the smile.
The term
“smile arc” has been used to describe the relationship
between the teeth and the lower lip in a posed smile.
The
smile arc is defined as “the relationship of the curvature
of the incisal edges of the maxillary incisors and canines
to the curvature of the lower lip in the posed smile.”12
The smile arc is related to the cant of the occlusal plane
and can be significantly affected during treatment by
excessive intrusion and inclination of the maxillary
incisors.4,9,12 Some clinicians believe the smile arc must be
maintained as a primary treatment goal.
They utilize the
smile arc to gauge bracket heights in an effort to minimize
the flattening of the arc that often occurs with
orthodontic treatment.9,12 Conversely, other research
downplays the importance of the smile arc.
Nanda and
Burstone have demonstrated that the smile arc is influenced
by head position and that it can be dramatically changed in
the same individual simply by moving the head up and down.4
7
Another interaction between the teeth and the smile is
the amount of space present lateral to the buccal surfaces
of the maxillary posterior teeth.
This space is referred
to as the “buccal corridor” and the concept was originally
developed as it related to denture fabrication by Frush and
Fisher.13
Frush and Fisher warned that to eliminate the
buccal corridor by the expansion of the dentition was
characteristic of a denture and the presence of the buccal
corridor created a more natural appearance.
Buccal
corridors have emerged in the contemporary orthodontic
literature as a controversial topic.
A study by Moore that
digitally manipulated the transverse dental dimension in
individuals found a positive correlation with reduced
buccal corridors and improved smile esthetics.14
Hulsey
found no correlation of buccal corridor size to smile
esthetics when unaltered smile photographs of different
subjects were judged by laypersons.15
A systematic review
of smile esthetics found that in studies that digitally
manipulated the buccal corridor in the same smile
photograph, the reduction in the size of buccal corridors
was positively correlated to improved smile esthetics.
However studies that examined buccal corridor sizes in
different subjects showed no correlation with excellent
smile esthetics.16
8
The position of the lips in a smile is also of great
importance to smile esthetics.
The level of upper lip
elevation while smiling, or the lip line, influences the
maxillary anterior tooth and gingival display.
In esthetic
smiles, the upper lip is elevated to the height of the
gingival margin of the maxillary anterior teeth.9,12
The lip
line differs by gender with women having a higher lip line
at rest. Because of this, women will have more incisor and
gingival display when smiling.
The lip line, both at rest
and during smiling, decreases in height during the normal
aging process.9
Sarver reports that an increased gingival
display with smiling is youthful in appearance and may help
to offset the normal appearance of aging.12
Tooth Morphology and Esthetic Perception
Dental morphology of the anterior teeth is relatively
unique to each individual.
Differences exist in the
roundness of the anterior teeth that can affect esthetic
perception.
Esthetic perception of anterior tooth
morphology was evaluated among laypeople,17,18 restorative
dentists,18 and orthodontists.18
In general, laypeople were
less critical of differences in anterior tooth morphology
and the shape of the maxillary canine did not significantly
9
influence a layperson’s esthetic perception.17
Restorative
dentists tended to prefer males to have less rounded (more
square) incisors and female incisor shape to be more
rounded while orthodontists were less discriminating of
incisor shape.
Interestingly, orthodontist’s preferences
for canine shape differed amongst the different type of
incisor configuration with a preference to pointed canines
in square incisors and rounded canines in rounded incisors.
Overall, canine morphology was not as significant to dental
esthetic perception as incisor morphology.
The author’s
attributed this to the fact that dental professionals
primarily associate the canine with function and not
esthetics.
The reduced relative proportion of canine
display in frontal smiling photographs could also be
responsible for the reduced significance of canine
morphology on esthetic perception.18
Quantification of Esthetic Outcomes
Although esthetic determination is subjective and
multifactorial,4 measurements exist that attempt to quantify
esthetic outcomes.
Two of the most common methods used to
quantify perceived esthetic outcomes are the visual analog
scale and the Q-sort.
10
The visual analog scale (VAS) is a method used to
quantify how esthetically pleasing one finds an outcome.
The individual utilizing the VAS places a hash mark along a
linear scale that is typically 100 millimeters in length.
In esthetic studies, one end of the linear scale would
represent excellent esthetics and the other would represent
poor esthetics.
This hash mark can then be measured from
either extreme to establish a numerical value of the
rater’s perception.
The VAS provides a result that is easy
to interpret, although raters tend to avoid the extremes of
the scale which can confound the results.19
The Q-sort is a method of evaluating esthetic outcomes
developed by Stephensen that has the judge rank the
treatment outcomes of a group of individuals.19
To
accomplish this, the judge picks out the best and worst
outcomes and separates them.
The judge continues to select
the best and worst remaining outcomes until all have been
selected.
Depending on the sample size, the rater will
select progressively more subjects during each round of
judgment.
Once the Q-sort is complete, it will generate a
quasi-normal curve that can be used to quantify objective
outcomes.19
11
The Q-sort and VAS have been applied to orthodontic
treatment outcomes by Schabel in two separate studies.
In
one study, the VAS and Q-sort were used to evaluate posttreatment smiles by orthodontists and laypersons to
determine which was more reliable.
Intraclass correlation
coefficient measures of reliability found the Q-sort to be
more reliable than the VAS. Correlation coefficients of the
average VAS and Q-sort scores were very high (r=0.96 for
both) but correlation coefficients of individual rating
groups (orthodontist vs. laypersons, males vs. females)
found a higher correlation with the Q-sort than the VAS.19
Another study by Schabel determined if any specific smile
characteristic was consistently evident in both esthetic
and unestethic treatment outcomes.
Of the several
parameters examined, the presence of mandibular incisors
when smiling was the only smile characteristic examined
that reliably predicted an unesthetic smile result.20
The
lack of quantifiable and reliable esthetic factors further
support the difficulty in quantifying esthetics in
orthodontic treatment.
12
Quantification of Skeletal and Dental Relationships
Orthodontists have utilized objective measures when
diagnosing malocclusions to maximize treatment outcomes.
The field of cephalometrics has extensively studied the
composition and growth of the craniofacial complex.
In the
Bolton-Brush Growth Study, a longitudinal series of lateral
and posterior-anterior (PA) cephalograms were taken
annually of individuals to quantify facial growth.
This
study and many others like it has generated normative data
about the position of the teeth, skeleton, and supporting
soft tissues.
Clinicians utilize this data in conjunction
with the clinical exam to assist in diagnosis, treatment
planning, and to assess growth and treatment outcomes.
The advent of cone beam computed tomography (CBCT)
scans in orthodontics now allows the clinician unrestricted
views of the dentition and skeleton.
Cone Beam CT scans
are so named for the cone shaped x-ray beam that utilizes a
fraction of the radiation when compared to traditional
multislice computed tomography scans.21
A lateral and
frontal cephalometric film can be constructed from the CBCT
volume.
Studies have examined the accuracy of measurements
taken directly from the CBCT volume22 as well as
measurements comparing constructed lateral21,23 and PA
13
cephalometric radiographs.24
In general, CBCT provide a
very accurate representation of dental and skeletal
anatomy.22
Lateral cephalometric radiographs compared to
CBCT constructed lateral cephalometric radiographs of dry
skulls showed statistically significant differences in
several standard measures, however these differences were
clinically insignificant when considering standard error of
landmark identification.21
A similar study of the
differences between constructed and standard PA
cephalometric radiographs found minor, clinically
insignificant differences in distance measurements, however
significant differences were found comparing many standard
angular measurements.24
The reason for these differences
were attributed to errors in head positioning of the CBCT
due to a lack of ear rods that are routinely used in
standard cephalometric radiology.
Advancements in Orthodontic Treatment
The field of orthodontics has undergone significant
advances in treatment efficacy.
One of the most
significant advances in dentistry and orthodontics are
dental implants.
Originally for restorative purposes, the
use of dental implants has expanded into the field of
14
orthodontics.
The first published case utilizing implants
for orthodontic purposes was in 1983 by Creekmore and
Ecklund for maxillary incisor intrusion.25,26
Years of
research and development in this field has yielded an
abundance of literature and treatment modalities.
With the
use of mini-screw implants, an orthodontist has more
control than ever of the dentition.
Orthognathic surgery is another such advance that
allows for significant movements of the maxilla, mandible,
and the dentition well beyond the limits of conventional
orthodontics with or without growth modification.7 Dramatic
skeletal, dental, and soft-tissue changes are possible with
surgical and orthodontic interdisciplinary care.
Now an orthodontist can visualize and diagnose a
malocclusion in three dimensions and can effectively
manipulate the dentition and supporting structures in three
planes of space.
The question arises of where exactly to
place the teeth to maximize treatment outcomes.
Orthodontists have relied upon the position of the
maxillary canine in orthodontic diagnosis and treatment
planning.
15
Functional Importance of Maxillary Canine
The maxillary canine is a considered by many to be of
utmost importance for the development of a functional
occlusion.27
The concept of “canine protected occlusion” is
based on a complete separation of the balancing side cusps
and contacts during a lateral excursive movement.27,28
The
advocates of canine protected occlusion cite
anthropological,29 electromyographic,27 and pathological30
evidence as the basis of their clinical decision making.
In theory, the long root and strong periodontal support of
the canine is best suited to bear the brunt of occlusal
forces during function.29
Some electromyography studies
have shown a decrease in masticatory muscle activity in
canine protected occlusions.27,31
Ronald Roth, one of the
pioneers of canine protected occlusion, advocated
orthodontic and equilibration therapy to eliminate
balancing interferences, which he believed to be in “close
association between the severity of temporomandibular joint
pain-dysfunction and the location of balancing
interferences on tooth-guided excursions.”30
Although the principles of canine protected occlusion
(CPO) appear valid and therapeutic anecdotally, current
literature does not completely support its benefits.
16
The
maxillary canine’s morphology and high level of periodontal
support is not in question, however the reduction in muscle
activity with canine protected occlusion and reduction in
temporomandibular joint dysfunction (TMD) has not held up
to current scientific scrutiny.
Electromyography studies
have been shown to have low levels of reliability and a
significant reduction in muscular activity with CPO has not
been found consistently.
also unclear.
The role of occlusion in TMD is
Bruxism and parafunction have been shown to
be independent of occlusal relationships and no causal
relationship has been found to support the notion that CPO,
or any occlusal scheme, can prevent or cure TMD.28,32
Parafunction, bruxism, and TMD are multi-factorial in
nature and the current therapeutic recommendations endorsed
by the American Dental Association supports management of
symptoms and therapy aimed at the reduction in damage to
the occlusal system and supporting structures.
Orthodontic
and restorative therapies are not advocated by the American
Dental Association as a cure or a method to prevent TMD.32
17
Maxillary Canine Positional Characteristics in Relation to
the Dental Arch
The arrangement of all the teeth in an esthetically
pleasing configuration is one of the primary objectives of
orthodontic therapy.
The quantification of the three-
dimensional position of the dentition was the focus of
Andrews’ study on tooth positions in untreated, excellent
occlusions.
He examined the dental configuration of 120
diagnostic models and quantified the intra-arch
relationships of the crowns of individual teeth.
In this
study, the maxillary canines exhibited a natural distal
inclination of the root compared to the crown.
He
developed a novel system to gauge the buccal-lingual
inclination of the dental crown by drawing a line tangent
to the center of the buccal surface of the dental crown and
compared it to a line drawn perpendicular to the occlusal
plane.
He found the maxillary canine to exhibit a lingual
crown inclination, which he denoted as negative crown
torque.10
He furthered his research and developed brackets
with a built-in tip value of +6˚ for non-extraction cases
and negative torque values built into the bracket base.33
Although Andrews was not the first to come up with the
notion of a pre-adjusted appliance,33 his research and
18
bracket system were instrumental in the technological
advancement of the specialty.
Three-dimensional imaging advancements have allowed
retesting of Andrews’ research with consideration of the
root and crown configuration in relation to the occlusal
plane.
A novel system developed by Tong et al examined the
dental angulations on CBCT volumes of 76 untreated patients
with near-normal occlusions.
The system implemented
oriented two points (center of the crown and the center of
the root) of each individual tooth and measured the long
axis against the occlusal plane.
This method was similar
to Andrews’ but takes into account the root in addition to
the crown.
The mesiodistal angulation of the right and
left maxillary canine was 11.99 and 10.79 degrees, a
statistically significant difference.
The faciolingual
inclination of the right and left maxillary canine was
20.33 and 21.18 degrees respectively and was not
statistically significant.
Although this study provided
valuable insight into the three-dimensional arrangement of
the dentition within the arch, more research is needed to
develop and confirm normative data for the teeth.
19
Maxillary Canine Position in Relation to Soft Tissue
Landmarks
Common protocol in prosthodontic education is to place
the maxillary canines “at the corner of the mouth.”34
Studies examining this have found variability among the
canines in relation to the corner of the mouth and
maxillary canines tend to be positioned mesial to the
corner of the mouth.
A study that directly measured the
canine position in adolescent males found a statistically
significant tendency for the right canine to be located
3.14 millimeters (mm) from cusp tip to the corner of the
mouth and was 3.00 mm for the left canine.34
Another study
evaluating vertical canine position in relation to the lips
found that the vertical exposure of the maxillary canine
measured against the resting lip was more consistent than
maxillary incisor exposure among all age groups evaluated
and also by gender.
The average canine exposure in females
was 0 mm (coincident with upper lip) with a range of -2 mm
(inferior to the upper lip) to +2 mm (superior to the upper
lip).
The average canine exposure in males was -0.5 mm
with a range of -3 mm to +2mm.35 Although resting lip
position in relation to anterior tooth display is a helpful
diagnostic aid, it is not used routinely by orthodontists.
20
Neither of these studies utilized skeletal landmarks when
establishing canine position and cannot be applied to
radiographic diagnostic measures used routinely in
orthodontics.
Maxillary Canine Position in Relation to Skeletal Landmarks
A review of the literature examining the normal
position of the maxillary canine in relation to the skull
yielded few results.
In 1924 Simon presented a paper about
his novel method of orthodontic diagnosis which was based
on skeletal and dental position in relation to the orbital
plane.
The orbital plane is defined as “a frontal plane
determined by the lowest point of the infraorbital ridge
and at right angles to the median sagittal and the
Frankfort horizontal planes.”2
Simon developed his orbital
plane theory from dried skulls by taking a sample of
“several hundred cases of jaws with correct anatomical
occlusion and examined them with the gnathostat.”1 He found
that “in most of these cases the orbital plane passes
through the cusps of the maxillary canines.” According to
Simon, in normal skulls the orbital plane would also be
coincident with the mandible at gnathion.
He developed a
system of diagnosis and treatment planning that would
21
classify both the skeletal and dental relationship.
This
would also serve as the basis of his treatment decisions.1
To determine the orbital plane on an individual basis
Simon utilized a facebow device to register the occlusal
relationship and then transferred this to an articulator.
His facebow device recorded the patient’s occlusion in
relation to Frankfort horizontal and also recorded the
position of left and right orbitale.
After the study
models were mounted on his articulator Simon had a record
of the patient’s occlusion in relation to Frankfort
horizontal and the orbital plane.
He had previously
ascertained that the mid-sagittal plane was best
represented by two points along the mid-palatal raphe by
studying dried skulls.
This set-up was referred to as a
“gnathostat model.”
22
Figure 2.2: Simon’s facebow and gnathostat devices utilized
to record the patient’s occlusion modified from his
original journal article.1
Simon also developed a system of taking patient
photographs that positioned the patient with Frankfort
horizontal parallel to the floor and the orbital plane
perpendicular to Frankfort horizontal.1
This system was
developed prior to the advent of cephalometrics and
therefore skeletal measurements could not be directly
assessed on individual patients.
23
Figure 2.3: Photostat apparatus developed by Simon used for
diagnosis and treatment planning modified from his original
journal article.1
A study evaluating the maxillary canine position in
dry skulls and the relation to the orbital plane was
presented in 1926 by Oppenheim.
He measured 159 skulls
with “normal” occlusions and reported that porion-orbitalcanine angle was on average 104.5 degrees with a range of
96 to 115 degrees, an angulation greater than what Simon
originally theorized.
In skulls with Class II, division 1
malocclusions the range was 98 to 120 degrees with an
average porion-orbital-canine angle of 109 degrees.2
The
author was unable to find a study re-examining Simon’s
orbital plane theory in vivo utilizing cephalometrics.
24
Summary and Statement of Purpose
An improvement in facial and dental esthetics is a
primary motivator in seeking orthodontic care.
The
orthodontic and dental literature has an abundance of
information about improving esthetics and treatment
outcomes.
The author was unable to find any current
literature examining maxillary canine position in relation
to the skull.
Additionally, little information is
available about the influence of maxillary canine position
on dental esthetics, even though it is considered to be one
of the most critical teeth in the mouth for both esthetics
and function.
The purpose of this study is threefold.
First, the normal maxillary canine position in relation to
skeletal landmarks will be determined.
Second, a post-
treatment three-dimensional assessment of maxillary canine
position utilizing CBCT volumes of Caucasian male and
female subjects will be completed.
Finally, the effect of
the maxillary canine position on esthetic perception of
frontal smiling photographs will be determined.
25
References
1. Simon PW. On gnathostatic diagnosis in orthodontics. Int
J Orthod Oral Surg Radiogr. 1924(X):755–785.
2. Bercea MN. Review of an Article by Professor Dr. A.
Oppenheim on “Prognathism from the Anthropolgical and
Orthodontic Viewpoints”. Angle Orthod. 1928;100-108.
3. Connolly CJ. Relation of the orbital plane to position
of teeth. Am J Phys Anthrop. 1927;(10):71–78
4. Burstone CJ, Nanda R. JCO Interviews, Part 1 facial
esthetics. J Clin Orthod. 2007;41(2):79-87.
5. Little AC, Jones BC, DeBruine LM. Facial attractiveness:
evolutionary based research. Philos T Roy Soc B.
2011;(366):1638–1659.
6. Jones BC, Little AC, Penton-Voak IS, Tiddeman BP, Burt
DM, Perrett DI. Facial symmetry and judgements of
apparent health Support(sic) for a “good genes”
explanation of the attractiveness-symmetry relationship.
Evol Hum Behav. 2001;(22):417-429.
7. Proffit WR, Fields HW, Sarver DM. Contemporary
Orthodontics. 2007;St. Louis: Mosby Elsevier.
8. Sarver DM. Principles of cosmetic dentistry in
orthodontics: Part 1. Shape and proportionality of
anterior teeth. Am J Orthod Dentofacial Orthop.
2004;126(6):749–753.
9. Sabri R. The eight components of a balanced smile. J
Clin Orthod. 2005; 39(3): 155-167.
10. Andrews LF. The six keys to normal occlusion. Am J
Orthod. 1972;62(3):296-309.
11. Sarver DM, Yanosky M. Principles of cosmetic dentistry
in orthodontics: part 2. Soft tissue laser technology
and cosmetic gingival contouring. Am J Orthod
Dentofacial Orthop. 2005;127(1):85–90.
26
12. Sarver DM. The importance of incisor positioning in the
esthetic smile: The smile arc. Am J Orthod Dentofacial
Orthop. 2001; 120(2):98-111.
13. Frush JP, Fisher RD. The dynesthetic interpretation of
the dentogenic concept. J Prothet Dent.1958; 8(4):558581.
14. Moore T, Southard KA, Casko JS, Qian F, Southard TE.
Buccal corridors and smile esthetics. Am J Orthod
Dentofacial Orthop. 2005; 127(2):208-213.
15. Hulsey CM. An esthetic evaluation of lip-teeth
relationships present in the smile. Am J Orthod.1970;
57(2):132-144.
16. Janson G, Branco NC, Fernandes TMF, Sathler R, Garib D,
Lauris JRP. Influence of orthodontic treatment, midline
position, buccal corridor and smile arc on smile
attractiveness. A systematic review. Angle Orthod.
2011; 81(1):153-161.
17. Heravi F, Rashed R, Abachizadeh H. Esthetic preferences
for the shape of anterior teeth in a posed smile. Am J
Orthod Dentofacial Orthop 2011;139(6):806–814.
18. Anderson KM, Behrents RG, McKinney T, Buschang PH.
Tooth shape preferences in an esthetic smile. Am J
Orthod Dentofacial Orthop. 2005;(128):458–465.
19. Schabel BJ, McNamara JA , Franch L, Baccetti T. Q-sort
assessment vs visual analog scale in the evaluation of
smile esthetics. Am J Orthod Dentofacial Orthop.
2009;135(4):S61-71.
20. Schabel BJ, Franch L, Baccetti T, McNamara JA.
Subjective vs objective evaluations of smile esthetics.
Am J Orthod Dentofacial Orthop. 2009;135(4):S72-79.
27
21. van Vlijmen OJC, Bergé SJ, Swennen GRJ, Bronkhorst EM,
Katsaros C, Kuijpers-Jagtam AM. Comparison of
cephalometric radiographs obtained from cone-beam
computed tomography scans and conventional radiographs.
J Oral Maxillofac Surg. 2009;67(1):92–97.
22. Baumgaertel S, Palomo MJ, Palomo L, Hans MG.
Reliability and accuracy of cone-beam computed
tomography dental measurements. Am J Orthod Dentofacial
Orthop. 2009;136(1):19-25.
23. Moshiri M, Scarfe WC, Hilgers ML, Scheetz JP, Silveira
AM, Farman AG. Accuracy of linear measurements from
imaging plate and lateral cephalometric images derived
from cone-beam computed tomography. Am J Orthod
Dentofacial Orthop. 2007;132(4):550-560.
24. van Vlijmen OJC, Maal TJJ, Berge´ SJ, Bronkhorst EM,
Katsaros C, Kuijpers-Jagtman AM. A comparison between
two-dimensional and three-dimensional cephalometry on
frontal radiographs and on cone beam computed tomography
scans of human skulls. Eur J Oral Sci 2009;117:300–305.
25. Creekmore TD, Eklund MK. The possibility of skeletal
anchorage. J Clin Orthod 1983;4(4):266–269.
26. Papadopoulos MA, Tarawneh F. The use of miniscrew
implants for temporary skeletal anchorage in
orthodontics: A comprehensive review. Oral Surg Oral Med
O 2007;103(5):e6–e15.
27. Okeson JP. Management of Temporomandibular Disorders
and Occlusion. 2008;St. Louis: Mosby Elsevier.
28. Rinchuse DJ, Kandasamy S, Sciote J. A contemporary and
evidence-based view of canine protected occlusion. Am J
Orthod Dentofacial Orthop 2007;132(1):90–102.
29. D’Amico, A. The canine teeth: normal functional
relation of the natural teeth of man. J S Calif Dent
Assoc 1958;26:6-23.
28
30. Roth RH. Temporomandibular pain-dysfunction and
occlusal relationships. Angle Orthod 1973;43(2):136–152.
31. Williamson EH, Lundquist DO. Anterior guidance: its
effect on electromyographic activity of the temporal and
masseter muscles. J Prosthet Dent 1983;49(6):816–823.
32. Management of temporomandibular disorders. National
Institutes of Health Technology Assessment Conference
Statement. JADA 1996;127(11):1595–1606.
33. Andrews LF. The straight-wire appliance. Br J Orthod
1979;6(3):125–143.
34. Parkash H, Bhalla LR, Khanna VK. Position of maxillary
canine tip in relation to corner of mouth. J Indian Dent
Assoc 1970;42(4):98–104.
35. Misch CE. Guidelines for maxillary incisal edge
position-a pilot study: the key is the canine. J
Prosthodont 2008;17(2):130–134.
29
CHAPTER 3: JOURNAL ARTICLE
Abstract
Introduction: Esthetic improvement is one of the primary
reasons individuals seek orthodontic treatment.
The
maxillary canine is considered by many to have great
importance for both function and esthetics.
Limited
information is available about the position of the
maxillary canine in relation to skeletal landmarks and if
the position can influence esthetic perception.
Purpose:
The purpose of this study was to evaluate the normal
maxillary canine position in relation to skeletal
landmarks, to determine post-treatment three-dimensional
maxillary canine position with Cone Beam CT images, and to
see if maxillary canine position could influence esthetic
perception.
Methods: The Bolton Standard template acted as
the control sample and the maxillary canine position was
determined by implementing a Cartesian coordinate system.
The right and left maxillary canines of 48 males and 48
females who received orthodontic treatment were analyzed by
digitization of Cone Beam CT volumes.
The subject’s post-
treatment smile photographs were ranked and quantified by
nine orthodontic residents who completed a Q-sort.
Correlations were determined between canine position and
30
esthetic outcomes. Results: The only difference between
right and left canine position was the anterior-posterior
position of the root apex.
Statistically significant
gender differences were found for the superior-inferior
position of the right and left canine cusp tip, the mediallateral right and left canine root apex, and the mediallateral left canine cusp tip.
No correlation was
determined between the maxillary canine position and
esthetic perception.
Conclusion: The maxillary canine
position in relation to skeletal landmarks was determined
and does not appear to significantly impact esthetic
perception according to this study.
31
Introduction
The improvement of facial and dental esthetics is one
of the primary reasons individuals seek orthodontic
treatment.
A large body of orthodontic literature exists
on the subject of dental esthetics.
Esthetic factors such
as a high-degree of facial symmetry, an upper lip-line upon
smiling that fully displays the upper incisors, and wellproportioned dental and gingival architecture have been
consistently found to improve esthetic perception.1–6
Conversely, esthetic factors such as smile-arc consonance,
the extent of buccal corridors, and the presence of the
golden proportion in soft and hard tissue is highly
contentious within the orthodontic literature.7–10
This
stems from the difficulty in objectifying and quantifying
esthetics, a topic that is greatly affected by cultural and
personal influences.1,11
Methods exist to attempt to quantify esthetic
outcomes.
One such method is the Visual Analog Scale
(VAS), which has a judge place a hash mark on a linear
scale that is typically 100 millimeters in length.
In an
esthetic study, one end would represent an excellent
esthetic outcome and the other would represent a poor
32
esthetic outcome.
The hash mark on the visual analog scale
can be measured to quantify a rater’s perception.
Although
the VAS is a method that is easy to complete and easy to
interpret, judges tend to avoid extremes which confounds
the results.12
Another method to quantify esthetic outcomes
is with a Q-sort.
A Q-sort involves a judge to separate
the best and worst esthetic outcomes.
The judge continues
to separate more of the best and worst remaining outcomes
until a quasi-normal curve is generated.
These two methods
of quantifying esthetics were examined in orthodontic
treatment outcomes by Schabel et al, they found that the Qsort was more reliable and had a higher correlation among
raters than the VAS.12
Orthodontists rely on a variety of diagnostic methods
to plan treatment in order to maximize esthetics,
stability, and function. Establishing a problem list and
treatment plan for each individual patient involves a
thorough assessment of the soft tissue characteristics,
skeletal relationships, and dental configuration.
Traditionally, orthodontic diagnosis was based on a lateral
cephalogram, which is a two-dimensional representation of a
three-dimensional object.
With the advent of Cone-Beam
33
Computed Tomography (CBCT) a new era of three-dimensional
diagnosis and treatment planning is on the horizon.
Orthodontic diagnosis has focused primarily upon the
position of the incisors and the molars in relation to the
other teeth, the skull, and the supporting soft tissue.
Interestingly, little information is available about
maxillary canine position in both normal and abnormal
dental and skeletal relationships, even though the canine
is considered by many to be of great importance to
occlusion and function.13,14
In the early 20th century German orthodontist Simon,
developed a method of diagnosis and treatment planning
hinged upon the maxillary canine’s position to the orbital
plane.15
The orbital plane is defined as “a frontal plane
determined by the lowest point of the infraorbital ridge
and at right angles to the median sagittal and the
Frankfort Horizontal planes.”16
Simon’s method of diagnosis
was dependent upon a sophisticated facebow and articulator
system that was able to reproduce a patient’s occlusion in
relation to Frankfort Horizontal, the mid-saggital plane,
and the orbital plane.
Simon used his articulator system
and measured dry skulls of patients with normal occlusion.
He reported that the orbital plane passed through the
34
maxillary canine and the embrasure between the mandibular
canine and first premolar in the majority of these cases.
Simon’s theory was re-evaluated by Oppenheim in 1928 with
conflicting results.
Oppenheim found that the maxillary
canine angle was not perpendicular to Frankfort Horizontal
as reported by Simon, but was more procumbent with an
average of 104.5 degrees.16
Both of these studies were
completed prior to the advent of cephalometrics.
A review
of the literature did not yield a current study examining
the relationship between maxillary canine position and
skeletal landmarks.
The purpose of this study is threefold.
First, the
normal maxillary canine position in relation to skeletal
landmarks will be determined.
Second, a post-treatment
three-dimensional assessment of maxillary canine position
utilizing CBCT volumes of Caucasian male and female
subjects will be completed.
Finally, the effect of the
maxillary canine position on esthetic perception of frontal
smiling photographs will be determined.
35
Materials and Methods
Control Sample
The control sample was composed of the Bolton Standard
Cephalometric Template of 15 year old males and females.
The Bolton Standard Template was created as a composite
average of 32 males and 32 females selected from the
Bolton-Brush Longitudinal Growth Study.
The subjects in
the Bolton Standard group had no orthodontic treatment and
were previously deemed to have excellent facial esthetics,
dental esthetics, and occlusal relationships.
The Bolton
Standard Template is comprised of both a lateral and
posterior-anterior (PA) tracing of excellent quality.
Orientation of Control Sample
A Cartesian coordinate system was utilized to
uniformly orient the PA and lateral tracings.
The x-axis
of the PA tracing was established through left and right
orbitale.
The y-axis of the PA cephalogram was constructed
through the facial midline at a perpendicular to x-axis.
The intersection of the x and y axis marked the (0,0)
point.
Because the Bolton Standard Template is constructed
from a series of PA cephalograms, which has the patient
face the x-ray film, the right and left side of the tracing
36
are reversed.
The Cartesian coordinate system for the
lateral cephalogram was established with Frankfort
Horizontal as the z-axis (horizontal).
The orbital plane,
as defined by Simon, was constructed by a perpendicular
plane from Frankfort Horizontal through orbitale and
represented the y-axis (vertical).
The (0,0) mark on the
lateral cephalogram was at the intersection of Frankfort
Horizontal and the orbital plane.
Figure 3.1: Orientation of the PA tracing.
37
Figure 3.2: Orientation of the lateral tracing.
Control Sample Cephalometric Landmarks
The landmarks identified on the lateral cephalogram
were canine cusp tip, canine root apex, orbitale, and
porion.
The landmarks identified on the PA cephalogram
were right maxillary canine cusp tip, right maxillary
canine root apex, left maxillary canine cusp tip, left
maxillary canine root apex, right orbitale, left orbitale,
right ear rod, and left ear rod.
38
Table 3.1: Cephalometric Landmarks of Control Sample
Porion (PO)
Orbitale (OR)
Canine Cusp Tip
(CCT)
Canine Root Apex
(CRA)
The midpoint of the line connecting the
most superior point of the radiopacity
generated by each of the two ear rods of
the cephalostat.17
The lowest point on the average of the
right and left borders of the bony
orbit.17
The cusp tip of the maxillary canine.
The apex of the maxillary canine.
Maxillary right and left canine cusp tip and apex were
identified and the (x,y) coordinates recorded on the PA
cephalogram.
The (z,y) coordinates were recorded on the
lateral cephalogram of the canine cusp tip and root apex.
The (z,y) coordinates from the lateral tracing were applied
to the right and left canine even though only one canine is
drawn on the Bolton Standard Template.
39
Figure 3.3: Cephalometric landmarks of PA tracing.
Figure 3.4: Cephalometric landmarks of lateral tracing.
40
Experimental Sample
The experimental sample was composed of the posttreatment Cone Beam CT (CBCT) scans of 48 Caucasian males
and 48 Caucasian females who had received orthodontic
treatment at Case Western Reserve University.
The subjects
were selected based on the following criteria:
a) The subject was Caucasian.
b) A post-treatment CBCT volume was available.
c) A post-treatment photograph of high quality was
available that showed the frontal smile.
d) The subject was 15 years old.
e) The subject had both right and left maxillary
canines.
f) The subject did not have maxillary canine
substitution treatment.
g) The subject did not have significant restorative
needs after orthodontic treatment.
For example,
subjects that needed restorations for missing and/or
traumatized teeth or prosthetic enhancement for
irregularly shaped teeth were excluded.
Orientation of Experimental Sample CBCT Volumes
The Cartesian coordinate system is determined by the
orientation of the volume and therefore a reproducible
41
system must be implemented.
Previous research using this
method oriented the skull into an x, y, and z axis’s.18
The
axial plane was represented by Frankfort Horizontal and was
composed of a plane through right and left orbitale
extending through right and left porion.
The mid-saggital
plane was created at a right angle to x-axis through the
anatomic facial midline determined by inspection through
crista galli and confirmed through sella turcica. The
frontal plane was constructed to mimic the orbital plane
and was generated by creating a plane perpendicular to
Frankfort Horizontal through right and left orbitale.
Figure 3.5: Orientation of the CBCT volume. A) X-Z axis
along Frankfort Horizontal. B) Y-Z axis perpendicular to Xaxis through mid-sella. C) X-Y axis connecting right and
left orbitale from the frontal view.
42
Measurement Methods of Experimental Sample
The CBCT volumes of the experimental sample were
evaluated using Dolphin 3D Imaging Software.
The multi-
planar viewing window allowed for simultaneous
visualization of the frontal, sagittal, and coronal planes.
The CBCT volume was rotated and orientated to allow
visualization of the pulp chamber of the right and left
maxillary canine.
Orientation of the long axis of the
maxillary canine was confirmed in all three planes of
space.
Establishing Data Points
The maxillary canine position was quantified by
digitizing the cusp tip and root apex of the right and left
canines.
The order the points digitized was always as
follows:
1) Right maxillary canine cusp tip
2) Right maxillary canine root apex
3) Left maxillary canine cusp tip
4) Right maxillary canine root apex
The digitized point’s accuracy was confirmed by visual
inspection of the other planes.
The coordinates were then
exported to Microsoft excel according to the Cartesian
43
coordinate system with (0,0,0) representing the
intersection of the X, Y, and Z axes.
Figure 3.6: Digitization of maxillary canine cusp tip and
root apex in Dolphin Imaging Software.
Determination of Canine Angulation and Position
Basic trigonometry was used to determine the lateral
and frontal angulation of the maxillary canines.
With the
maxillary canine representing the hypotenuse of a right
triangle, the two remaining sides were determined by
finding the differences between the horizontal and vertical
points. For example, when examining the frontal canine
angle:
44
X2-X1 = Horizontal Leg of Triangle (A)
Y2-Y1 = Vertical Leg of Triangle (B)
The Pythagorean Theorem was then used to determine the
length of the maxillary canine (hypotenuse) by the formula:
A2 (Horizontal Leg) + B2 (Vertical Leg) = C2 (Hypotenuse)
The angle of the maxillary canine was determined by finding
the inverse tangent.
The formula for determining this
angle is:
Inverse tangent(Opposite/Adjacent) = Canine Angle
or
Inverse tangent (A/B) = Canine Angle
The maxillary canine angulation from the lateral view
was determined in the exact same way with the z-axis
orientated along the horizon and maintaining the y-axis as
the vertical axis.
The maxillary canine angulation was
determined by using inverse tangent as described
previously.
Q-Sort
As described earlier, the Q-sort method of judging
esthetics is considered to be an effective and reliable way
to quantify esthetics.
Traditionally a Q-sort requires the judge to rate a
sample of 96 subjects.
Previous studies12,19 have shown that
45
a sample size of 48 is adequate to satisfy the requirements
of a Q-sort.
In this study, two separate Q-sorts were
completed of photographs of 48 male subjects and 48 female
subjects to assess if any gender differences exist.
Post-treatment photographs of the frontal smile were
cropped to 3 x 5 inches.
Confounding anatomic factors such
as the nose, eyes, and hair were cropped from the
photograph.
Photoshop® Software was used to remove any
blemishes that could influence rater’s perception.
Figure 3.7: Example of smile photograph used during Q-sort.
Nine third year orthodontic residents from the
Graduate Orthodontics Department of Saint Louis University
Center for Advanced Dental Education volunteered to perform
the Q-sort.
The subjects were given consent forms in
46
accordance to Saint Louis University’s Institutional Review
Board and agreed to participate in the study.
Each
resident completed two separate Q-sorts, one of the male
subjects and one of the female subjects.
The instructions
given to each judge were as follows:
“From the 48 photographs please pick the two best and
two least esthetic smiles based only on the available
photographs.
Set aside the two best and the two worst at
separate ends of the table.
From the remaining 44
photographs please select the four best and four least
esthetic smiles and set aside.
From the remaining 36
photographs please select the five best and five least
esthetic smiles.
From the remaining 26 photographs please
select the eight best and eight least esthetic smiles
remaining.
The ten photographs remaining should represent
what you consider to be average looking smiles.”
Statistics
Statistics were calculated with SPSS 20.0 Statistical
Software (SPSS, Inc., Chicago, IL).
Descriptive statistics
of the experimental sample were determined of the
coordinate and angular measures.
The x, y, and z
coordinates of the canine cusp tip and apex of each
experimental subject was compared to the control sample by
47
measuring the linear distance from the control value.
To
accomplish this six total scatter plots were generated of
the canine cusp tip and root apex of the maxillary right
canine.
The scatter plot was orientated along the XY, YZ,
and XZ axes and consisted of the control sample and all 96
subjects from the experimental sample.
To determine the linear distance between the normal
canine coordinates and experimental subject coordinates
right angle trigonometry was utilized.
The horizontal and
vertical distance from the norm of each subject was
determined.
This created a right triangle with the
hypotenuse representing the linear distance between the two
points.
The Pythagorean Theorem is used to calculate the
length of the hypotenuse.
A2 (Horizontal Leg) + B2 (Vertical Leg) = C2
(Hypotenuse)
The Q-sort was analyzed by assigning a point value to
each subject depending upon the esthetic category he/she
was placed.
This generated a system to quantify, rank, and
distribute the esthetic outcomes.
Q-sort distributions
were also generated of the linear distances of the canine
cusp tip and root apex of the maxillary right canine.
Correlations were calculated between the best and worst
48
esthetic results as well as the best and worst canine
position results.
To calculate reliability of the study 12 of the CBCT
volumes were re-orientated and re-digitized.
The
Cronbach’s Alpha measure of reliability was utilized.
A
Cronbach’s Alpha greater than 0.80 is considered reliable.
49
Results
Error Study
The Cronbach’s Alpha was 0.876 for the total combined
digitized landmarks and re-orientation.
This value
indicates that the repeated measurements were not
statistically significant from the original data points.
Control Sample Results
The x, y, and z coordinates of the maxillary canines
from the control sample were determined from the Bolton
Standard Templates.
Because only one canine was traced for
the lateral cephalogram template, the y and z data was
applied to both the right and left side. The y coordinate
could be determined from both the lateral and frontal
template but the y value from the frontal template was used
exclusively.
The y values of the canine cusp differed by
4% for the canine cusp and apex.
50
Table 3.2: Bolton Standard Cartesian Coordinates –
Male/Female PA Tracing (mm)
Right Canine
Cusp
Right Canine
Apex
Left Canine
Cusp
Left Canine
Apex
X
-17
Y
-50
-13
-23
19
-50
14
-23
Table 3.3: Bolton Standard Cartesian Coordinates –
Male/Female Lateral Tracing (mm)
Right Canine
Cusp
Right Canine
Apex
Left Canine
Cusp
Left Canine
Apex
Z
7.5
Y
-52
3.5
-24
7.5
-52
3.5
-24
The angular measures of the control sample were
determined by direct measurement.
The frontal canine angle
is the angle of the maxillary canine to the mid-sagittal
plane.
The lateral canine angle is the angle of the
maxillary canine to Frankfort Horizontal.
Table 3.4: Bolton Standard Angular Measurements –
Male/Female (degrees)
Right Canine
Frontal Angle
Left Canine
Frontal Angle
Lateral Canine
Angle
9
10
99
51
Descriptive Statistics of Experimental Sample
Descriptive statistics of the x, y, and z coordinates
of the experimental sample were calculated from the CBCT
volumes.
The x coordinates, which represent the right and
left distance from the midline, tended to have the smallest
range and standard deviation compared to y and z
coordinates.
Table 3.5: Descriptive Statistics of Digitized Landmarks
(mm) of Experimental Sample – Total Sample (n=96)
Right
Canine Cusp
X
Right
Canine Cusp
Y
Right
Canine Cusp
Z
Right
Canine Apex
X
Right
Canine Apex
Y
Right
Canine Apex
Z
Left Canine
Cusp X
Left Canine
Cusp Y
Left Canine
Cusp Z
Left Canine
Apex X
Left Canine
Apex Y
Left Canine
Apex Z
Mean
(SD)
-17.5
(1.4)
Median
Mode
Range (Min/Max)
-17.3
-16.7
8.5
(-22/-13.5)
-47.7
(3.2)
-47.1
-45.4
14.4
(-55.8/-42.6)
10.6
(3.3)
11.2
9.2
16.1
(1.8/-17.9)
-14.1
(1.8)
-14.2
-14.2
9.3
(-19.1 - -9.8)
-24.5
(2.7)
-24.2
-23.8
12.7
(-32.1/-19.4)
4.7
(2.5)
4.9
7
12
(-1/11)
17.2
(1.4)
-47.6
(3.1)
10.7
(3.2)
13.9
(1.8)
-24.4
(2.8)
4.4
(2.4)
17.1
16.6
-47.2
-46.1
11.0
11.5
13.9
14.4
-24.3
-21.2
4.6
5.8
6.2
(14.4/20.6)
15
(-55.6/-40.6)
15.1
(3.5/18.6)
10
(9.3/19.3)
12.8
(-32.3/-19.5)
10.6
(-0.7/9.9)
52
Table 3.6: Descriptive Statistics of Angular Measurements
of Experimental Sample (degrees) – Total Sample (n=96)
Right Canine
Frontal
Angle
Left Canine
Frontal
Angle
Right Canine
Lateral
Angle
Left Canine
Lateral
Angle
Mean
(SD)
8.8
+/- 4.8
Media
n
8.6
Mode
Range (Min-Max)
-4.5
25.7
(-4.5 – 21.1)
-8.5
+/-4.8
-8.9
.00
25.3
(-18.9 – 6.3)
104.5
+/- 5.3
104.5
106.1
27.4
(90.8 – 118.2)
105.2
+/-5.6
105.0
104.6
26.5
(90.6 – 117.1)
53
A Student t-Test was completed to determine
statistically significant differences in all parameters
between genders.
Table 3.7: Comparison of Gender Difference in Experimental
Sample
Right Canine
Cusp X
Right Canine
Cusp Y
Right Canine
Cusp Z
Right Canine
Apex X
Right Canine
Apex Y
Right Canine
Apex Z
Left Canine
Cusp X
Left Canine
Cusp Y
Left Canine
Cusp Z
Left Canine
Apex X
Left Canine
Apex Y
Left Canine
Apex Z
Males
(n=48)
Mean
SD
-17.7
1.4
Females
(n=48)
Intergroup
Differences
Mean
-17.4
SD
1.4
.225
-49.0
3.0
-46.4
3.0
.000*
10.5
3.5
10.8
3.2
.640
-14.5
1.7
-13.6
1.7
.008*
-24.5
2.6
-24.5
2.9
.987
4.4
2.5
5.1
2.4
.159
17.5
1.4
16.8
1.3
.016*
-48.9
2.8
-46.5
3.0
.000*
10.4
3.3
10.9
3.1
.408
14.6
1.7
13.1
1.5
.000*
-24.3
2.5
-24.5
3.1
.784
4.1
2.6
4.7
2.2
.164
*Denotes statistically significant (p<0.05).
The results of the Student T-Test show statistically
significant gender differences between several factors
including right and left cups tip Y coordinates, right and
left canine apex X coordinates, and the left canine cusp X
coordinate.
54
A paired sample t-test was used to determine any
differences between the right and left side canine position
in the experimental sample.
Table 3.8: Comparison of Right and Left Maxillary Canine
Position of Experimental Sample (n=96)
Correlation
t-test
Paired Differences
r
P
Mean
S.D.
P
Canine
.121
.240
.36
1.86
.058
Cusp X*
Canine
.954
.000
-.04
.97
.722
Cusp Y
Canine
.955
.000
-.01
.99
.886
Cusp Z
Canine
.232
.023
.21
2.20
.354
Apex X*
Canine
.845
.000
-.04
1.54
.812
Apex Y
Canine
.877
.000
.30
1.21
.017†
Apex Z
*Absolute values used to relate distance from midline.
†Denotes statistically significant (p<0.05).
A strong correlation exists between the Y and Z
coordinates for the cusp and apex.
A weak correlation
exists between the X coordinates of the cusp and apex.
only coordinate to have a statistically significant
difference between the right and left side was the Z
coordinate of the canine apex.
55
The
Scatter Plot Data
Scatter plots of the Bolton standard (n=1) and the
experimental sample (n=96) were generated to create a
visual representation of the canine coordinate data.
0
-25
-20
-15
-10
-5
0
-10
-20
X-Y Right Canine Cusp
Experimental Sample
X-Y Right Canine Cusp
Bolton Standard
-30
-40
-50
-60
Figure 3.8: Scatter Plot of XY right canine cusp tip.
56
0
-25
-20
-15
-10
-5
0
-10
X-Y Right Canine Apex Experimental
Sample
-20
X-Y Right Canine Apex Bolton
Standard
-30
-40
-50
-60
Figure 3.9: Scatter plot of XY axis of right canine root
apex.
57
0
0
5
10
15
20
25
-10
Z-Y Right Canine Cusp
Experimental Sample
Z-Y Right Canine Cusp Bolton
Standard
-20
-30
-40
-50
-60
Figure 3.10: Scatter Plot of ZY axis of right canine cusp
tip.
58
0
-5
0
5
10
15
20
25
Z-Y Right Canine Apex Experimental
Sample
-10
Z-Y Right Canine Apex Bolton
Standard
-20
-30
-40
-50
-60
Figure 3.11: Scatter Plot of ZY axis of right canine root
apex.
59
25
X-Z Right Canine Cusp
Experimental Sample
20
X-Z Right Canine Cusp Bolton
Standard
15
10
5
0
0
-5
-10
-15
-20
-25
Figure 3.12: Scatter plot of XZ axis of right canine cusp
tip. The points are on a horizontal plane from a superior
view.
60
25
X-Z Right Canine Apex
Experimental Scatter
20
X-Z Right Canine Apex Bolton
Standard
15
10
5
0
0
-5
-10
-15
-20
-25
-5
Figure 3.13: Scatter plot of XZ root apex. The points are
on a horizontal plane from a superior view.
Maxillary Canine Position Patterns
The XY position of the canine cusp tip is ovoid in
shape with the superior-inferior position of the canine
having nearly twice the range of the medial-lateral
position.
The XY position of the root apex however is more
circular in shape, with superior-inferior range only 3 mm
greater than the medial-lateral position range.
In both
instances a high density of experimental subjects are very
61
near the normal position of the cusp tip and root apex.
The pattern of the YZ position of the canine cusp tip
resembles a parallelogram and has a similar range of
superior-inferior and anterior-posterior position.
The
pattern of the YZ position of the root apex resembles a
square.
The density of the experimental subjects in
proximity to the norm is much less when examining the
canine cusp tip compared to the root apex.
The pattern of
the XZ canine cusp tip is rectangular in shape with the
anterior-posterior position having twice the range of the
medial-lateral.
The XZ pattern of the root apex is also
rectangular in shape with the anterior-posterior position
slightly larger than the medial-lateral position.
In both
instances the highest density of experimental subjects is
in the central portion of the scatter, however in both the
control position of the maxillary canine cusp tip and root
apex is more medial and posterior.
62
Esthetic Results
The raters who completed the Q-sort generated 9
columns based on his/her esthetic preference.
To calculate
the results of the Q-sort, each subject was assigned a
point value from 1 (least esthetic) to 9 (most esthetic)
based on which column the rater placed the subject.
The
total point value of each subject was calculated by adding
the results of all 9 Q-sorts.
The subjects were ranked and
a histogram of the total esthetic results was created.
Histogram of Esthetic Q-Sort Result
25
Frequency
20
15
10
Frequency
5
0
0
10
20
30
40
50
60
70
80
More
Bin
Figure 3.14: Histogram of the total esthetic scores of all
the subjects. The Kurtosis of the histogram is -0.42 and
the skewness is 0.10.
63
Esthetic Results in Relation to Canine Position
The linear distance from the norm (Bolton standard) of
each subject was determined by right angle trigonometry.
The ranks of the individuals were applied to the same
frequency distribution as the Q-sort to create equal
distributions.
The histograms of the linear distances of
each subject from the norm were generated and the results
are reported in Appendix A.
The linear distances from the
norm were ranked and frequencies were created that were
identical in distribution to the esthetic Q-sort.
The canine position of the four best and four worst
esthetic outcomes were evaluated by determining the
frequency score.
The frequency score was calculated by
recording the score of the column where each subject was
located in relation to the total distribution.
64
Esthetic Scores (X) vs. Total Canine Position (Y)
50
45
40
35
30
25
20
15
10
5
0
y = -0.0032x + 29.229
R² = 1E-04
Esthetic Scores vs. Canine
Position
Linear (Esthetic Scores vs.
Canine Position)
0
20
40
60
80
100
Figure 3.15: Graph and correlation of the four subjects
with the highest combined esthetic scores, four subjects
with average combined esthetic scores, and the four
subjects with the lowest combined esthetic scores in
relation to total canine position coordinate scores
Esthetic Scores (X) vs. XY Canine Position (Y)
18
16
y = 0.0011x + 9.8644
R² = 7E-05
14
12
Esthetic Scores (X) vs. Canine
Position (Y)
10
8
Linear (Esthetic Scores (X) vs.
Canine Position (Y))
6
4
2
0
0
20
40
60
80
100
Figure 3.16: Graph and correlation of the four subjects
with the highest combined esthetic scores, four subjects
with average combined esthetic scores, and the four
subjects with the lowest combined esthetic scores in
relation to XY axis canine position coordinate scores.
65
Esthetic Scores (X) vs. ZY Canine Position (Y)
20
18
16
14
12
10
8
6
4
2
0
y = 0.0039x + 9.8198
R² = 0.0008
Esthetic Scores (X) vs. ZY
Canine Position (Y)
Linear (Esthetic Scores (X)
vs. ZY Canine Position (Y))
0
20
40
60
80
100
Figure 3.17: Graph and correlation of the four subjects
with the highest combined esthetic scores, four subjects
with average combined esthetic scores, and the four
subjects with the lowest combined esthetic scores in
relation to ZY axis canine position coordinate scores.
Esthetic Scores (X) vs. XZ Canine Position (Y)
14
y = -0.0083x + 9.5448
R² = 0.0057
12
10
Esthetic Scores (X) vs. XZ
Canine Position (Y)
8
6
Linear (Esthetic Scores (X)
vs. XZ Canine Position (Y))
4
2
0
0
20
40
60
80
100
Figure 3.18: Graph and correlation of the four subjects
with the highest combined esthetic scores, four subjects
with average combined esthetic scores, and the four
subjects with the lowest combined esthetic scores in
relation to XZ axis canine position coordinate scores.
66
Table 3.9: Correlations of Esthetic Scores and Maxillary
Canine Position Scores
Total Canine XY Canine ZY Canine
XZ Canine
Position
Position
Position
Position
2
R
0.0001
0.00007
0.0008
0.0057
Graphs of the canine positions of the four best and
four worst esthetic outcomes were compared to the Bolton
Standard Template in the XY and YZ axis and are in Appendix
B.
Esthetic scores of the four best, four worst, and
average total canine positions were also evaluated by
determining the frequency score.
A correlation of the
subjects with the best total canine position score was run
against their respective esthetic scores.
Total Canine Position Scores (X) vs.
Esthetic Scores (Y)
70
60
y = 0.2384x + 33.321
R² = 0.0347
50
40
30
Canine Position Scores
(X) vs. Esthetic Scores
20
10
0
0
10
20
30
40
50
Linear (Canine Position
Scores (X) vs. Esthetic
Scores)
Figure 3.19: Graph and correlation of the four subjects
with the highest combined esthetic scores, four subjects
with average combined esthetic scores, and the four
subjects with the lowest combined esthetic scores in
relation to ZY axis canine position coordinate scores.
67
The pictures of the subjects with the best and worst
esthetic outcomes are in Appendix C and the pictures of the
subjects with the best and worst total canine position
outcomes are in Appendix D.
68
Discussion
The purpose of this study was to evaluate the
maxillary canine position in relation to maxillary skeletal
position in a normal and a treated population. The
influence of maxillary canine position on dental esthetics
was also evaluated.
Three Dimensional Assessment of Maxillary Canine Position
To establish control data, a Cartesian coordinate
system was implemented to determine the maxillary canine
position of the Bolton Standard Template.
A similar
Cartesian coordinate system was utilized on a sample of
CBCT volumes.
A reliability study found the orientation
and digitization method utilized in this study to be
reliable.
Descriptive statistics of the average three
dimensional positional data of the maxillary canines was
determined.
The only statistically significant difference
between the right and left canine position was between the
z coordinates of the canine apex.
Gender differences in
canine position were assessed as well.
Statistically
significant differences were found in the right and left
canine cusp y coordinates, the right and left canine apex x
69
coordinates, and the left canine cusp x coordinate.
The
reason for these differences is unclear.
The large sample size of the experimental sample
provided an insight into the range of maxillary canine
positions in three dimensions.
The scatter plots offered
visualizations of the anatomic distribution of the
maxillary canine cusp tip and root apex.
The range of the
medial-lateral and anterior-posterior position of the
canine cusp was smaller than the root apex.
Conversely,
the range of the superior-inferior position of the canine
apex is smaller than the cusp tip.
The reason behind the
differences in ranges of the positions is unclear.
All the
CBCT volumes studied were taken after orthodontic
treatment.
Tooth movement is initiated at the level of the
crown, where the bracket is attached.
Orthodontic
treatment typically is not completed without coupling of
the maxillary canine to the mandibular dentition.
Moving
the maxillary canine into a position dictated in part by
the mandibular dentition potentially reduces the influence
of the maxillary skeletal anatomy on canine position.
Changes in root morphology occur during orthodontic
treatment due to root resorption and maturation of the
root.
The morphology of the canine crown is dictated prior
to starting orthodontic therapy and barring significant
70
restorations or recontouring should not change during the
course of treatment.
A matched sample of pre-treatment
CBCT volumes could provide more insight into treatment
effects on canine position.
Without this information or a
three-dimensional norm definitive conclusions cannot be
determined.
The lateral angular measures of both the Bolton
Standard and the experimental sample were 99 and 105
degrees respectively.
This data conflicted with Simon’s
Orbital Plane theory as the canines in the experimental
sample were more protrusive and less upright. Oppenheim‘s
study on a large sample (n=159) of dry skulls found the
lateral canine to average 104.5 degrees, which is in near
perfect agreement with our study.
The frontal canine angle
of the experimental sample was 8.8 degrees for the right
canine and 8.5 degrees the left which was slightly more
upright than the norm values.
The author was unable to
find any other study examining the frontal canine angle for
comparison.
Maxillary Canine Position and Esthetic Perception
The influence of maxillary canine position and
esthetic perception was assessed.
The Bolton Standard was
considered to be the ideal for canine position, dental
71
esthetics, and facial esthetics.
The linear distance from
the ideal was determined of all experimental subjects in
all three axes.
Normal distributions of the distances from
the ideal were created and a scoring system was implemented
to grade the subjects on their position within the
frequency.
The distances from the norms and the position
of the subjects within the frequencies were correlated to
the four best, the four worst, and four average esthetic
outcomes.
No correlation was found between esthetic
outcome and maxillary canine position.
Esthetic outcomes
were compared to the three principal axes (XY, YZ, and XZ)
and again no correlation was found.
No correlation was
found when evaluating the best, worst, and average canine
positions with esthetic outcomes.
Esthetic perception is highly variable and multifactorial.
Personal preferences also significantly affect
esthetic perception.
The Q-sort the nine judges completed
did yield a relatively normal distribution of esthetic
outcomes but canine position appears to have little
influence on overall esthetic perception.
Anatomic factors
such as lip thickness, dental morphology, and gingival
display affect esthetic perception.
Previous studies
examining maxillary anterior crown morphology supports the
notion that individuals may not be examining maxillary
72
canine teeth as critically as the other anterior teeth.20
Perhaps a more effective way to determine the maxillary
canine’s position on esthetics would be to alter the
position digitally within one picture of a subject’s smile.
This would reduce the confounding factors that influence
esthetic perception among different individuals.
The majority of orthodontic diagnosis is based on the
lateral cephalogram, a two-dimensional representation of a
three-dimensional object.
Technological advances such as
CBCT scans, three-dimensional soft-tissue rendering, and
CAD/CAM study models may start to shift attention away from
the midline and towards the dentofacial complex as a whole.
Improved treatment methods such as skeletal anchorage and
orthognathic surgery afford the clinician unprecedented
control of the dentition and supporting tissues.
With
continued research in this field an orthodontist will be
able to maximize treatment outcomes and best serve his/her
patients.
73
Conclusion
The post-treatment position of the maxillary canine
had a statistically significant difference between the left
and right anterior-posterior position of the apex.
Statistically significant gender differences were found for
the superior-inferior position of the right and left canine
cusp tip, the mesial-lateral right and left canine apex,
and the medial-lateral left canine cusp.
The lateral
angulation of maxillary canine was more obtuse than
originally hypothesized by Simon.
The difference in
frontal canine angulation was not statistically
significant.
No correlation was found between the subjects with the
best or worst esthetic outcomes and their respective canine
position.
The subjects with the best canine position also
had no correlation to esthetic outcomes.
74
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2. Sarver DM. Principles of cosmetic dentistry in
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anterior teeth. Am J Orthod Dentofacial Orthop.
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3. Sarver DM, Yanosky M. Principles of cosmetic dentistry in
orthodontics: part 2. Soft tissue laser technology and
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Orthop. 2005;127(1):85–90.
4. Sabri R. The eight components of a balanced smile. J Clin
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Okeson JP. Management of Temporomandibular Disorders
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Bercea MN. Review of an Article by Professor Dr. A.
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77
Appendix A
Frequency
Histogram
16
14
12
10
8
6
4
2
0
Frequency
Bin
Figure 3.20: Histogram of linear distances from the XY
coordinate Bolton Standard of the right canine cusp. The
kurtosis is -0.57 and the skewness is 0.35.
Histogram
30
Frequency
25
20
15
10
Frequency
5
0
Bin
Figure 3.21: Histogram of the linear distances from the XY
coordinate of the Bolton Standard of the right canine apex.
The kurtosis is 0.74 and the skewness is 0.83.
78
Frequency
Histogram
16
14
12
10
8
6
4
2
0
Frequency
Bin
Figure 3.22: Histogram of the linear distances from the ZY
coordinate of the Bolton Standard of the right canine cusp.
The kurtosis is -0.66 and the skewness is 0.15.
Histogram
30
Frequency
25
20
15
10
Frequency
5
0
Bin
Figure 3.23: Histogram of the linear distances from the ZY
coordinate of the Bolton Standard of the right canine apex.
The kurtosis is 1.33 and the skewness is 0.85.
79
16
14
12
10
8
6
4
2
0
More
12
11
10
9
8
7
6
5
4
3
2
1
Frequency
0
Frequency
Histogram
Bin
Figure 3.24: Histogram of the linear distances from the XZ
coordinate of the Bolton Standard of the right canine cusp.
The kurtosis is -0.25 and the skewness is 0.50.
Histogram
30
Frequency
25
20
15
Frequency
10
5
0
0
1
2
3
4
5
6
7
8
9
More
Bin
Figure 3.25: Histogram of the linear distances from the XZ
coordinate of the Bolton Standard of the right canine apex.
The kurtosis is 0.36 and the skewness is 0.71.
80
Appendix B
Figure 3.26: Graph of four best and worst esthetic outcome
XY canine position compared to the Bolton Standard.
Figure 3.27: Graph of four best and worst esthetic outcome
YZ canine position compared to the Bolton Standard.
81
Appendix C
Figure 3.28:
scores
Four subjects with highest combined esthetic
82
Figure 3.29:
scores
Four subjects with lowest combined esthetic
83
Appendix D
Figure 3.30: Smile photographs of four subjects with
highest combined canine position scores.
84
Figure 3.31: Smile photographs of four subjects with lowest
combined canine position scores
85
Vita Auctoris
John Katsis III was born in Hinsdale, Illinois on May
10th, 1983 to Dr. John Katsis Jr. and Joan Katsis.
He has
two older sisters who are teachers and one younger brother
who is in medical school.
He graduated from Hinsdale
Central High School in 2001.
He graduated with High Honors
from the University of Illinois at Urbana-Champaign in May
2005 with a Bachelors of Science in Kinesiology.
John began his dental education at the University of
Illinois at Chicago in August of 2006.
As both the son of
an orthodontist and the benefactor of orthodontic
treatment, he was fully aware of the personal and
professional satisfaction that the field of orthodontics
offered.
In May of 2010 he graduated from dental school
and delivered one of two student commencement speeches.
He was accepted to the orthodontics residency program
at Saint Louis University in December of 2009 and began his
residency in June of 2010.
He plans to complete his
Masters of Science in Dentistry in December 2012.
After
graduation, John will join his father’s orthodontic
practices in Bartlett and Bloomingdale, Illinois.
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