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FACIAL PROFILE CHANGES WITH EXTRACTION OF FOUR FIRST
PREMOLARS IN CAUCASIAN, CLASS I, MINIMALLY-CROWDED,
ADOLESCENT PATIENTS
Daniel J. Cloward, D.M.D.
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
2013
Abstract
Purpose:
The purpose of this study is to investigate the
effect that the extraction of four first premolars has on
the facial profiles of Caucasian, Class I, minimallycrowded, adolescent patients.
Materials and Methods:
A
sample of 30 subjects was selected from the archives at
Saint Louis University Center for Advanced Dental
Education.
Cases were selected based on these criteria: 1)
Caucasian, 2) adolescent, 3) Class I molar relationship, 4)
treatment with extraction of four first premolars, 5) <5 mm
of initial crowding in the most crowded arch.
Pretreatment
(T1) and post treatment (T2) cephalograms were analyzed.
Paired t-tests were performed to analyze the differences
between the pre- and post-treatment values.
Linear
regression analysis was performed to evaluate the strength
of correlation between incisor and lip retraction.
Results:
There was a statistically significant decrease in
the horizontal distance for the upper lip, lower lip, upper
incisor, and lower incisor.
The reduction of the upper and
lower lip to E-plane was -2.82 mm and -3.47 mm
respectively.
The mean ratio for the retraction of the
upper incisor to upper lip was 2.1:1 (r=.619), and for the
lower incisor to lower lip was 1.1:1 (r=.874).
1
Conclusions:
Upper and lower lip protrusion was reduced
resulting in an overall flattening of the facial profile.
There was a moderate correlation between retraction of the
upper incisors and upper lip, but there was an even
stronger correlation between retraction of the lower
incisors and lower lip.
2
FACIAL PROFILE CHANGES WITH EXTRACTION OF FOUR FIRST
PREMOLARS IN CAUCASIAN, CLASS I, MINIMALLY-CROWDED,
ADOLESCENT PATIENTS
Daniel J. Cloward, D.M.D.
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
2013
COMMITTEE IN CHARGE OF CANDIDACY:
Professor Eustaquio A. Araujo,
Chairperson and Advisor
Professor Rolf G. Behrents
Associate Professor Ki Beom Kim
i
DEDICATION
This work is dedicated to my wife, Heather.
Thank you
for your constant love and support during my orthodontic
residency.
Thank you for your patience as I have pursued
my dream beyond dental school to become an orthodontist.
Thank you also to my children, Tyler, Tessa, Olivia,
and Jayden for sharing their father to the educational and
professional process to become an orthodontist.
Also,
thank you for providing me balance and joy throughout this
journey.
And lastly, to the faculty of Saint Louis University,
it has been an honor to have been trained under your
exceptional guidance.
Your instruction and mentorship will
serve as a strong foundation for the rest of my
professional career.
ii
ACKNOWLEDGEMENTS
This project could not have been completed without the
help and support of the following individuals:
Dr. Eustaquio Araujo.
Thank you for your guidance
during my thesis preparation and for enriching my education
with your tremendous dedication and enthusiasm for
orthodontics.
Dr. Rolf Behrents.
Thank you for your contributions
to my thesis and allowing me to obtain an orthodontic
education at Saint Louis University.
Dr. Ki Beom Kim.
Thank you for your guidance during
my thesis preparation and revisions, and for the value that
you have added to my clinical education.
Dr. Heidi Israel.
Thank you for your assistance with
the statistical analysis for this thesis.
iii
TABLE OF CONTENTS
List of Tables............................................v
List of Figures..........................................vi
CHAPTER 1: INTRODUCTION...................................1
CHAPTER 2: REVIEW OF THE LITERATURE
Normal Dental Occlusion..............................2
Class I Dental Malocclusion..........................2
Definition......................................2
Prevalence......................................3
Orthodontic Treatment...........................3
Prevalence of Extractions............................4
Effect of Extractions on Facial Profile..............6
Relation of Incisor Position to Lip Position........11
Statement of Thesis.................................16
Literature Cited....................................18
CHAPTER 3: JOURNAL ARTICLE
Abstract............................................21
Introduction........................................23
Materials and Methods...............................24
Sample.........................................24
Methodology....................................24
Statistical Analysis...........................28
Reliability....................................28
Results.............................................29
Horizontal Measurements........................29
Vertical Measurements..........................30
Angular Measurements...........................31
Linear Regression Analysis.....................33
Discussion..........................................35
Conclusions.........................................41
Literature Cited....................................42
Appendix.................................................44
Vita Auctoris............................................45
iv
LIST OF TABLES
Table 2.1
Change in lip position to E-Plane following
premolar extraction........................8
Table 2.2
Effects of incisor retraction on the upper
and lower lip.............................13
Table 3.1
Changes in cephalometric horizontal
measurements..............................29
Table 3.2
Changes in cephalometric vertical
measurements..............................30
Table 3.3
Changes in cephalometric angular
measurements..............................32
Table 3.4
Relationship between incisor retraction and
subsequent lip change.....................33
Table 3.5
Comparison of change in lip position to EPlane following premolar extraction in
previous studies compared with the present
study.....................................37
Table 3.6
Comparison of the effects of incisor
retraction on the upper and lower lip in
previous studies with the present
study.....................................38
Table A.1
Landmarks and Definitions.................44
v
LIST OF FIGURES
Figure 2.1
Prevalence of extractions of four first
premolars at five year intervals...........5
Figure 3.1
Landmarks located.........................25
Figure 3.2
Reference planes..........................26
Figure 3.3
Combined horizontal and vertical changes in
mm for the upper and lower incisors and lips
from T1 to T2.............................31
Figure 3.4
Scatter gram of upper incisor to upper lip
retraction for each subject in the
study.....................................34
Figure 3.5
Scatter gram of lower incisor to lower lip
retraction for each subject in the
study.....................................34
vi
CHAPTER 1: INTRODUCTION
There have been many studies that have examined the
changes in facial profile that occur as a result of
bicuspid extractions during orthodontic treatment.
This
area of research has been important because a primary
consideration when making orthodontic treatment decisions
is assessing how the treatment will affect the patient’s
facial profile.
Past studies have shown that premolar extractions
generally result in some flattening of the face.1-9
This
can be either advantageous or detrimental depending on the
particular patient’s profile.
Other studies have attempted
to quantify the relationship between the amount of incisor
retraction and the subsequent amount of lip retraction.10-17
While some of these studies have established a significant
correlation between these variables, there has been great
individual variation.
Few studies, if any, have considered the amount of
crowding that patients exhibit pretreatment when measuring
the effect that premolar extraction had on the facial
profile.
The purpose of this study is to investigate the
effect that the extraction of four first premolars has on
the facial profiles of Caucasian, Class I, minimallycrowded, adolescent patients.
1
CHAPTER 2: REVIEW OF THE LITERATURE
Normal Dental Occlusion
Early on the focus of orthodontics was on alignment of
teeth and the correction of facial proportions.
There was
little emphasis placed on bite relationships or how the
teeth came together.
It wasn’t until the late 1800s that
the concept of occlusion was formally defined.
Angle as
“the father of modern orthodontics” gave us the first clear
and simple definition of normal occlusion.
He believed
that the upper molars were the key to occlusion and that
the upper and lower molars should be related so that the
mesiobuccal cusp of the upper molar occludes in the buccal
groove of the lower molar.18
If a person has this molar
relationship along with their teeth being arranged along a
smoothly curving line of occlusion, they are considered to
have a normal occlusion.
Class I Dental Malocclusion
Definition
Angle described three classes of malocclusion, based
on the occlusal relationships of the first molars.
In
Class I malocclusion the molars have a normal relationship,
as previously described for a normal occlusion, but the
2
line of occlusion is incorrect because of malpositioned
teeth, rotations, or other irregularities.18
Prevalence
The NHANES III survey provided a picture of how many
American children and youths fall into each of Angle’s four
groups of occlusion.
Estimates from this survey, showed
that a maximum of 30% had normal occlusion.
Approximately
50 to 55% had Class I malocclusion which made up the single
largest group.
Approximately 15% had Class II
malocclusion, and less than 1% were classified as Class
III.19
Orthodontic Treatment
In general, patients with a Class I malocclusion with
minimal crowding or an arch length discrepancy of less than
4 mm, are treated without extractions.
When arch length
discrepancy ranges from 5 to 9 mm, such cases are
considered borderline for extraction treatment.
Then when
crowding becomes 10 mm or more, extractions are almost
always required.
The presence of protrusion in addition to crowding can
also complicate the decision whether to extract teeth or
not in the patient with a Class I malocclusion.20
3
Prevalence of Extractions
Throughout history the acceptance of extractions as a
viable form of treatment has swung from one extreme to the
other. Angle was a strong advocate for nonextraction
treatment, but then later on Tweed became one of the
strongest advocates for extractions.
In 1966, Tweed
estimated the extraction rate in orthodontics to be about
80%.21
In 1979, a study of extraction frequency from an
office in the Northeastern United States estimated that the
prevalence of extraction treatment to be around 42% of
orthodontic cases.22
In 1993, O’Connor looked at contemporary trends in
orthodontics based on the previous five years.
A large
survey of practitioners across the United States showed a
decline in the reported extraction rate from 38% to 29%.23
In 1994, Proffit looked at changes in extraction rate over
the previous forty year period.24
The most frequently used
extraction pattern to treat crowding is four first
premolars.
Figure 2.1 demonstrates the prevalence of this
pattern over a forty year period.
4
FOUR FIRST PREMOLAR EXTRACTIONS
PERCENT OF PATIENTS
60
50
40
30
20
10
0
1953
1958
1963
1968
1973
1978
1983
1988
1993
Figure 2.1. Prevalence of extractions of four first
premolars at five year intervals. Adapted from Proffit.24
Proffit also reported the total extraction percentage
over the same time period.
He estimated the extraction
rate to be about 30% in 1953.
It then peaked at 76% in
1968, with the belief that extractions would enhance
stability.
28% in 1993.
The rates then declined, and reached a rate of
Reasons noted for the decline from 1983 to
1993 were for improved facial esthetics, the belief that
extractions weren’t necessarily more stable, TMJ concerns,
and changes in treatment technique.24
5
Effect of Extractions on Facial Profile
An article by Bowman and Johnston evaluated the
perceptions of dentists and laypersons on the esthetic
impact of extraction and non-extraction treatments on
Caucasian patients.1
The non-extraction treatment was seen
to have little effect on profile, whereas extractions were
seen as beneficial to the profile in cases that exhibited
greater initial protrusion.
In their sample, the
extraction patient’s profiles after treatment were on
average 1.8 mm flatter than the non-extraction patients.
Regression analysis showed that both dentists and
laypersons saw extractions as being beneficial when the
lips were more protrusive than 2 to 3 mm behind Ricketts’
E-plane.
Ricketts defined the “E-plane” as a line from the nose
to the chin and claimed that most people have an aversion
to the lips that protrude past this plane.
He claimed the
upper lip should be related to the lower lip and the lower
lip should be considered the main reference.
He believed
that the ideal adult lower lip should be located 4 mm
behind the E-plane +/-3 mm.25
Bishara assessed the perception that laypersons have
on the profile changes that occurred for patients that
underwent extraction of four first premolars or had
6
nonextraction treatment.
normal control group.26
These were also compared to a
Immediately after treatment, judges
perceived the changes in the profile of the extraction
group more favorably than the non-extraction and normal
groups.
However, at 2 years posttreatment, the raters did
not evaluate the profile of any of the groups as being more
favorable, but that all were perceived as more favorable
than before treatment.
Boley also evaluated the perceptions of 192
experienced general dentists and orthodontists.27
Facial
photos were collected from the main author’s practice and
consisted of 25 consecutively treated nonextraction
patients and 25 consecutively treated four-premolarextraction patients. The photos were randomized, and the
dental professionals were asked to discern which cases they
felt were treated with extractions.
They were only correct
54% of the time, which was only slightly better than pure
chance.
For many years, the desire to achieve or maintain
ideal facial esthetics has been a factor in deciding
whether or not to extract teeth during orthodontic
treatment.
There have been numerous studies conducted that
attempt to evaluate or quantify the effects that
extractions have on the facial profile.1-9
7
Many of the
extraction studies have used Rickett’s E-plane to evaluate
the amount of profile change that occurs during treatment.
These results are summarized in Table 2.1.
Table 2.1. Change in lip position to E-Plane following
premolar extraction
Investigator
Lip Change
Upper Lip
Lower Lip
Kocadereli2
-1.0
-1.1
Drobocky and Smith3
-3.4
-3.6
James4
-3.3
Bishara et al5
-3.7
-3.4
Paquette et al6
-3.1
Luppanapornlarp et al7
-2.9
Bravo8
-3.4
Bowman and Johnston1
-3.8
-2.5
Luecke and Johnston9
-2.4
-1.4
Kocadereli’s study included a sample of 80 white
patients that had an Angle Class I malocclusion.
Half of
the sample underwent extraction of four first premolars,
while the other half were treated nonextraction.2
The
average retraction of the upper lip and lower lip for the
extraction group with respect to the E-plane was 1.0 mm and
1.1 mm respectively.
This was a significantly greater
reduction than for the nonextraction group even though for
8
both groups the lips moved posterior in relation to the E
plane.
The maxillary and mandibular incisors showed
significant retroclination in the extraction group, whereas
in the nonextraction group, there was a noticeable
proclination of the incisors.
Another study by Drobocky and Smith examined the
change in facial profile for a large sample of 160 patients
from different sources that were also treated with removal
of four first premolars.3
Mean changes following the
extraction treatment were retraction of the upper and lower
lips behind the E line of -3.4 mm and -3.6 mm respectively,
and an increase in the nasolabial angle of 5.2 degrees.
Also, 80 to 90% of the patients had soft tissue
measurements that indicated the profile either improved or
remained satisfactory throughout treatment.
James conducted a study using 170 consecutively
treated cases, 108 of which were treated with extractions
and 62 without extractions.4
He showed a change in the
lower lip to E plane of -3.3 mm for the extraction group,
and -1.1 mm for the nonextraction group.
When broken down
by extraction pattern, extraction of four first premolars
showed the greatest change at -3.77 mm.
It was interesting
to note that the posttreatment lower lip E-value for the
extraction group (E = -2.6) was very close to the
9
pretreatment value for the nonextraction group (E = -2.9).
In other words, the extraction group’s final profile was
about the same as the nonextraction group’s starting
profile.
Bishara et al demonstrated in a sample of 44 Class II
Division 1 patients that had extraction of four first
premolars a significant reduction in lip protrusion.5
There
was a change from the upper and lower lip from the E-plane
of -3.7 mm and -3.4 mm respectively.
In the nonextraction
group the E-values actually increased.
Additionally, the
extraction group had more upright maxillary and mandibular
incisors following treatment, whereas the nonextraction
group had opposite tendencies.
Paquette et al showed a change of -3.1 mm of the lower
lip to E-plane following extractions in Class II Division 1
patients that were classified as “borderline” for
extractions.
This compared to a change of -0.6 mm for the
comparable nonextraction group.6
Luppanapornlarp et al then
showed a change of -2.9 mm for the lower lip to E-plane for
a “clear-cut” Class II extraction group, compared to -0.5
mm in the study’s nonextraction group.7
Bravo conducted a small study of 16 adolescent
Caucasian female patients that were treated with extraction
of four premolars.
His study also showed a reduction in
10
lip protrusion following treatment.
The change of the
upper and lower lips to the E-plane was -3.4 mm and -3.8 mm
respectively.8
Bowman and Johnston also showed a reduction
in lip protrusion from the sample in their study.
They
showed a decrease in the lower lip to E-plane of 2.5 mm.1
However, this wasn’t as large of a decrease as has been
demonstrated in some of the other former studies.
Luecke and Johnston measured the effect of premolar
extractions on the soft tissues.
Their study consisted of
42 Class II Division 1 patients that had maxillary first
premolars removed.
Changes were measured parallel to the
mean functional occlusal plane.
The incisors were
retracted significantly, but this only resulted in 1.4 mm
of maxillary lip retraction and 0.1 mm of mandibular lip
retraction. This was translated into a change in the upper
and lower lips to the E-plane of -2.4 mm and -1.4 mm
respectively.9
Relation of Incisor Position to Lip Position
The lips and soft tissues surrounding the oral cavity
play a significant role in facial esthetics.
The soft
tissues surrounding the mouth are in close proximity to the
dentition.
There are several articles in the past
literature that have sought to explore this relationship
11
between the hard and soft tissues of the perioral cavity.1017, 28-35
Riedel found that the changes in the soft tissue
profile correlated well with changes in the skeletal
profile.28
Subtelny explains that the position of the soft
tissues covering the lower jaw and the maxillary and
mandibular dentoalveolar areas is strongly dependent on the
position of the hard tissue structures.
He stresses that
the strong interrelationship between the lips and the
dental structures is obviously important to the
orthodontist.29
Bloom conducted a study of 60 male and female
adolescents to evaluate the relationship between the
changes to incisor position and resulting soft tissue
changes.30
His scatter diagrams of the change in incisor
and lip positions showed a strong linear relationship.
While the upper lip was shown to follow the movement of the
upper incisors (r=.87), there was an even stronger
correlation between the lower lip and the lower incisors
(r=.93).
Another study by Hershey had a sample of 36 Caucasian
postadolescent females, 32 of which had four first
premolars extracted and the other 4 were treated without
extractions.
He found a stronger correlation between
12
retraction of upper incisor to the upper lip (r=.79) than
for the lower incisor to lower lip (r=.52).
He also noted
that the correlation of the lower incisor to the lower and
upper lip was much stronger for the patients in the Class I
group.31
Many authors also support a direct correlation between
the incisor position and lip position, although some report
greater correlations than others.10-17
The ratio of incisor
to lip retraction in these studies is summarized in Table
2.2.
Table 2.2. Effects of incisor retraction on the upper and
lower lip
Investigator
Ratio
U1 : U Lip
L1 : L Lip
Rudee10
2.9 : 1
0.6 : 1
Roos11
2.5 : 1
1.0 : 1
Garner12
3.6 : 1
1.0 : 1
Lo and Hunter13
2.5 : 1
Waldman14
3.8 : 1
Perkins and Staley15
2.2 : 1
Kasai16
2.4 : 1
Hanson17
2.0 : 1
13
1.3 : 1
Rudee investigated the relationship between the
incisors and lips in 85 consecutively treated patients from
his office.
The ratio for upper incisor to upper lip
retraction was 2.9:1 (r=.73), and for lower incisor to
lower lip was .6:1 (r=.70).10
Roos showed similar ratios of
2.5:1 (r=.42) for the upper incisor to upper lip, and 1:1
(r=.82) for the lower incisor to lower lip.11
also showed similar ratios.
Other studies
Lo and Hunter13 recorded a
ratio of 2.5:1 (r=.77)for upper incisor to upper lip
retraction, and Perkins and Staley15 reported the ratio of
2.2:1.
In a sample of 16 African American adolescents, Garner
reported a ratio of 3.6:1 for the upper incisor to upper
lip retraction, and 1:1 for the lower incisor to lower
lip.12
There was a high degree of individual variation
among patients and there was less predictability for
retraction of the upper lip than for the lower lip.
Waldman also reported a ratio of 3.8:1 for upper incisor to
upper lip retraction in a study of 41 Class II patients.14
His sample also showed a large variability among patients.
In a study of 32 Japanese women treated with four
premolar extractions, Kasai concluded using a multiple
regression analysis that movement of the lower lip could be
predicted fairly well by lower incisor retraction, but that
14
upper incisor retraction had a weaker association in
predicting upper lip movement.
The reported ratio for the
upper incisor to upper lip retraction was 2.4:1.16
This
weaker association may be due to the complex anatomy and
dynamics of the upper lip which is suspended from the nose
and the anterior nasal spine.36
Hanson completed a thesis at Saint Louis University,
where she looked at different extraction patterns and the
resulting dental and soft tissue changes.
She reported
relatively good correlations between incisor movement and
lip position.
The ratio for the upper incisor to upper lip
was 2:1 (r=.71) and the lower incisor to lower lip was
1.3:1 (r=.73).17
Some authors have reported that there does not seem to
be a direct correlation between incisor retraction and lip
response.32,
34, 35
Burstone stated that if a redundancy of
lip tissue exists, most likely the tissue will not fall
back following retrusion of the teeth.32
He claims that
there may be a postulated anteroposterior position of the
lips independent of the teeth.
This is demonstrated in
samples of dentulous and edentulous people.
Oliver also
demonstrated in his study of 40 Caucasian patients with a
Class II, Division 1 malocclusion that lip thickness
affects the correlation between incisor retraction and
15
subsequent soft tissue response.
He found that there was a
high correlation for patients with thin lips or with high
lip strain, but that there was a weak correlation for
patients with thick lips or low lip strain.33
Neger showed cases where the dentoskeletal changes
were significant, but net change in soft tissue profile was
rather slight.
He also showed cases where the profile
improved significantly following retraction of teeth, so he
saw variable results in different cases.34
Wylie evaluated
cases that Tweed had treated and made the argument that it
wasn’t the angulation or position of the lower incisor that
improved the facial profile in his cases.
Rather, he
claimed that it was primarily mandibular growth that should
be credited for the improvement in facial profile.35
Overall, there appears to be some degree of
relationship between changes in incisor position and
resulting changes in the soft tissues.
However, the
strength of this correlation appears to differ among
individuals.
Statement of Thesis
Extractions are often times performed to alleviate
crowding and to correct anterior-posterior discrepancies of
the occlusion.
They are also performed to decrease or
16
limit protrusion of the lips and dentition.
There is
generally some flattening of the facial profile following
extraction treatment.
This can either be beneficial or
detrimental to the patient’s profile depending on the case.
While there have been other studies that have
evaluated the soft tissue profile changes following
extraction treatment, few studies have attempted to control
for the amount of crowding or the initial anteriorposterior relationship of the occlusion.
This
investigation seeks to evaluate the soft tissue profile
changes that occur for Class I patients with minimal
crowding that undergo orthodontic treatment that includes
extraction of four first premolars.
17
Literature Cited
1. Bowman SJ, Johnston LE, Jr. The esthetic impact of
extraction and nonextraction treatments on Caucasian
patients. Angle Orthod. 2000;70:3-10.
2. Kocadereli I. Changes in soft tissue profile after
orthodontic treatment with and without extractions. Am
J Orthod Dentofacial Orthop. 2002;122:67-72.
3. Drobocky OB, Smith RJ. Changes in facial profile during
orthodontic treatment with extraction of four first
premolars. Am J Orthod Dentofacial Orthop.
1989;95:220-30.
4. James RD. A comparative study of facial profiles in
extraction and nonextraction treatment. Am J Orthod
Dentofacial Orthop. 1998;114:265-76.
5. Bishara SE, Cummins DM, Jakobsen JR, Zaher AR.
Dentofacial and soft tissue changes in Class II,
division 1 cases treated with and without extractions.
Am J Orthod Dentofacial Orthop. 1995;107:28-37.
6. Paquette DE, Beattie JR, Johnston LE, Jr. A long-term
comparison of nonextraction and premolar extraction
edgewise therapy in "borderline" Class II patients. Am
J Orthod Dentofacial Orthop. 1992;102:1-14.
7. Luppanapornlarp S, Johnston LE, Jr. The effects of
premolar-extraction: a long-term comparison of
outcomes in "clear-cut" extraction and nonextraction
Class II patients. Angle Orthod. 1993;63:257-72.
8. Bravo LA. Soft tissue facial profile changes after
orthodontic treatment with four premolars extracted.
Angle Orthod. 1994;64:31-42.
9. Luecke PE, 3rd, Johnston LE, Jr. The effect of maxillary
first premolar extraction and incisor retraction on
mandibular position: testing the central dogma of
"functional orthodontics". Am J Orthod Dentofacial
Orthop. 1992;101:4-12.
10. Rudee DA. Proportional profile changes concurrent with
orthodontic therapy. Am J Orthod. 1964;72:165-75.
18
11. Roos N. Soft-tissue profile changes in Class II
treatment. Am J Orthod. 1977;72:165-75.
12. Garner LD. Soft-tissue changes concurrent with
orthodontic tooth movement. Am J Orthod. 1974;66:36777.
13. Lo FD, Hunter WS. Changes in nasolabial angle related
to maxillary incisor retraction. Am J Orthod.
1982;82:384-91.
14. Waldman BH. Change in lip contour with maxillary
incisor retraction. Angle Orthod. 1982;52:129-34.
15. Perkins RA, Staley RN. Change in lip vermilion height
during orthodontic treatment. Am J Orthod Dentofacial
Orthop. 1993;103:147-54.
16. Kasai K. Soft tissue adaptability to hard tissues in
facial profiles. Am J Orthod Dentofacial Orthop.
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17. Hanson RA. Incisor retraction and lip response with
various extraction patterns in caucasian females.
Saint Louis: Saint Louis University; 2003.
18. Angle EH. Treatments of Malocclusion of the Teeth. 7th
ed. Philadelphia: SS White Dent Mfg Co; 1907.
19. Proffit WR, Fields HW, Jr., Moray LJ. Prevalence of
malocclusion and orthodontic treatment need in the
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Int J Adult Orthodon Orthognath Surg. 1998;13:97-106.
20. Proffit WR, Fields Jr. HW, Sarver DM. Contemporary
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2007.
21. Tweed CH. Clinical Orthodontics. Saint Louis: C. V.
Mosby; 1966.
22. Peck S, Peck H. Frequency of tooth extraction in
orthodontic treatment. Am J Orthod. 1979;76:491-6.
23. O'Connor BM. Contemporary trends in orthodontic
practice: a national survey. Am J Orthod Dentofacial
Orthop. 1993;103:163-70.
19
24. Proffit WR. Forty-year review of extraction frequencies
at a university orthodontic clinic. Angle Orthod.
1994;64:407-14.
25. Ricketts RM. Esthetics, environment, and the law of lip
relation. Am J Orthod. 1968;54:272-89.
26. Bishara SE, Jakobsen JR. Profile changes in patients
treated with and without extractions: assessments by
lay people. Am J Orthod Dentofacial Orthop.
1997;112:639-44.
27. Boley JC, Pontier JP, Smith S, Fulbright M. Facial
changes in extraction and nonextraction patients.
Angle Orthod. 1998;68:539-46.
28. Riedel RA. An analysis of dentofacial relationships. Am
J Orthod. 1957;43:103-19.
29. Subtelny JD. The soft tissue profile, growth and
treatment changes. Angle Orthod. 1961;31:105-22.
30. Bloom LA. Perioral profile changes in orthodontic
treatment. Am J Orthod. 1961;47:371-9.
31. Hershey HG. Incisor tooth retraction and subsequent
profile change in postadolescent female patients. Am J
Orthod. 1972;61:45-54.
32. Burstone CJ. Lip posture and its significance in
treatment planning. Am J Orthod. 1967;53:262-84.
33. Oliver BM. The influence of lip thickness and strain on
upper lip response to incisor retraction. Am J Orthod.
1982;82:141-9.
34. Neger M. A quantitative method for the evaluation of
the soft-tissue facial profile. Am J Orthod.
1959;45:739-51.
35. Wylie WL. The mandibular incisor--its role in facial
esthetics. Angle Orthod. 1955;25:32-41.
36. Talass MF, Talass L, Baker RC. Soft-tissue profile
changes resulting from retraction of maxillary
incisors. Am J Orthod Dentofacial Orthop. 1987;91:38594.
20
CHAPTER 3: JOURNAL ARTICLE
Abstract
Purpose:
The purpose of this study is to investigate the
effect that the extraction of four first premolars has on
the facial profiles of Caucasian, Class I, minimallycrowded, adolescent patients.
Materials and Methods:
A
sample of 30 subjects was selected from the archives at
Saint Louis University Center for Advanced Dental
Education.
Cases were selected based on these criteria: 1)
Caucasian, 2) adolescent, 3) Class I molar relationship, 4)
treatment with extraction of four first premolars, 5) <5 mm
of initial crowding in the most crowded arch.
Pretreatment
(T1) and post treatment (T2) cephalograms were analyzed.
Paired t-tests were performed to analyze the differences
between the pre- and post-treatment values.
Linear
regression analysis was performed to evaluate the strength
of correlation between incisor and lip retraction.
Results:
There was a statistically significant decrease in
the horizontal distance for the upper lip, lower lip, upper
incisor, and lower incisor.
The reduction of the upper and
lower lip to E-plane was -2.82 mm and -3.47 mm
respectively.
The mean ratio for the retraction of the
upper incisor to upper lip was 2.1:1 (r=.619), and for the
21
lower incisor to lower lip was 1.1:1 (r=.874).
Conclusions:
Upper and lower lip protrusion was reduced
resulting in an overall flattening of the facial profile.
There was a moderate correlation between retraction of the
upper incisors and upper lip, but there was an even
stronger correlation between retraction of the lower
incisors and lower lip.
22
Introduction
There have been many studies that have examined the
changes in facial profile that occur as a result of
bicuspid extractions during orthodontic treatment.
This
area of research has been important because a primary
consideration when making orthodontic treatment decisions
is assessing how the treatment will affect the patient’s
facial profile.
Past studies have shown that premolar extractions
generally result in some flattening of the face.1-9
This
can be either advantageous or detrimental depending on the
particular patient’s profile.
Other studies have attempted
to quantify the relationship between the amount of incisor
retraction and the subsequent amount of lip retraction.10-17
While some of these studies have established a significant
correlation between these variables, there has been great
individual variation.
Few studies, if any, have considered the amount of
crowding that patients exhibit pretreatment when measuring
the effect that premolar extraction had on the facial
profile.
The purpose of this study is to investigate the
effect that the extraction of four first premolars has on
the facial profiles of Caucasian, Class I, minimallycrowded, adolescent patients.
23
Materials and Methods
Sample
A sample of 30 subjects was selected from the records
at Saint Louis University Center for Advanced Dental
Education.
Cases for the sample were selected based on
these inclusion criteria: 1) Caucasian, 2) adolescent, 3)
Class I molar relationship, 4) treatment with extraction of
four first premolars, 5) <5 mm of initial crowding in the
most crowded arch.
Crowding was determined by visual
analysis of the dental casts.
If there was a question of
too much crowding, a Tooth Size Arch Length Discrepancy
(TSALD) analysis was performed, and the case was either
included or excluded based on these results.
The 30 subjects in the study consisted of 18 females
and 12 males.
The average age for the sample at the onset
of treatment (T1) was 12.76 +/- 1.25 years and the average
age at the end of treatment (T2) was 15.05 +/- 1.2 years.
This resulted in an average treatment time of about 2.29
years.
Methodology
From each of the patient records, pre-treatment (T1)
and post-treatment (T2) cephalograms were traced in order
to acquire the necessary measurements for the study.
24
For
each of the cephalograms, 12 hard and soft tissue
anatomical landmarks were located. Their definitions can be
found in the Appendix Table A.1 and a diagram of their
corresponding location is seen in Figure 3.1. These
landmarks were traced at both time points (T1 and T2), then
digitized using Dentofacial Planner software (Dentofacial
Software, Inc. Dentofacial Planner, Version 7.0, Toronto,
Canada).
Figure 3.1.
Landmarks located
25
Within Dentofacial Planner, two reference planes were
constructed in order to create an x-y coordinate grid. A
horizontal line was created parallel to the sella-nasion
line minus 7 degrees (SN-7) and a vertical line was created
perpendicular to this line (SN-7) passing through the
landmark sella. This is diagrammed in Figure 3.2.
Figure 3.2.
Reference Planes
26
From the landmarks and reference planes, 11 linear and
3 angular measurements were derived and computed by the
Dentofacial Planner software.
Horizontal and vertical
measurements from the x-y reference planes were made for
upper lip, lower lip, upper incisor, and lower incisor.
Also measured were the upper and lower lips to the E-plane
and the linear vertical measure of Nasion to Menton.
Angular measures consisted of the angle between the
mandibular plane (Gonion to Menton) and the long axis of
the lower incisor (IMPA), angle between the Sella to Nasion
plane and the long axis of the upper incisor (U1 to SN),
and the angle between the upper and lower incisor (U1 to
L1).
The data was corrected for magnification differences
between T1 and T2 on an individual basis.
The percentage
of enlargement was adjusted based on equalizing the
distances from sella to nasion (S-N).
In this sample the
distance was mostly larger for the T2 cephalograms, so
these measurements were reduced by the individual
enlargement factor.
Since magnification does not affect
angular measurements, all angles in the study were excluded
from being multiplied by a correction factor.
27
Statistical analysis
All measurements were taken from T1 and T2
cephalograms.
Descriptive data was obtained and
statistical analysis was performed using the Statistical
Package for the Social Science (IBM SPSS, Version 20,
Armonk, NY).
Differences between the pre- and post-
treatment values were analyzed using paired t-tests for
each of the variables.
A significance level of p<.05 was
set to assess the difference between the variables for
times T1 to T2.
Associations between incisor retraction
and relative lip changes were analyzed using a linear
regression analysis.
Reliability
Cronbach’s alpha was used to determine consistency of
measurements.
Reliability is considered to be “adequate”
when intra-class correlations are greater than or equal to
0.80.
Five sets of cephalograms were randomly selected and
re-measured to test for intra-examiner reliability.
The
results indicated that the Cronbach’s alpha was well above
0.80 for all variables.
This showed that the original
measurements and repeated measurements were at an
acceptable level of reliability for accuracy of
measurements.
28
Results
Horizontal Measurements
All of the measurements in the horizontal axis showed
statistically significant changes from T1 to T2; all of
these measures showed a decrease.
The results also showed
a decrease of the upper and lower lip to E-plane of -2.82
mm and –3.47 mm respectively.
Details are given below in
Table 3.1.
Table 3.1. Changes in cephalometric horizontal
measurements
Horizontal Measures
Time
Variable
T1
T2
Mean Change
Mean
SD
Mean
SD
Mean
SD
Sig.
Upper Lip
88.76
4.58
86.40
4.71
-2.37
2.37
.000*
Lower Lip
85.56
5.43
82.68
5.61
-2.89
2.45
.000*
Upper Incisor
75.23
5.43
70.27
5.48
-4.95
2.75
.000*
Lower Incisor
71.13
4.99
67.85
5.45
-3.28
1.89
.000*
UL to Eplane
-0.62
2.28
-3.44
2.27
-2.82
1.47
.000*
LL to Eplane
2.14
2.69
-1.33
2.59
-3.47
1.59
.000*
*P < .01
29
Vertical Measurements
The results for the vertical axis measurements from T1
to T2 showed statistically significant changes for the
upper lip and lower incisor.
significant increase.
These two measures showed a
Also, the vertical measure of nasion
to menton showed a significant increase for the anterior
facial height.
The vertical measures for lower lip and
upper incisor did not yield statistically significant
differences. Details are below in Table 3.2.
Table 3.2.
Changes in cephalometric vertical measurements
Vertical Measures
Time
Variable
T1
T2
Mean Change
Mean
SD
Mean
SD
Mean
SD
Sig.
Upper Lip
64.65
5.36
66.15
5.16
1.50
1.94
.000*
Lower Lip
80.68
5.87
81.47
5.41
.79
2.37
.080
Upper Incisor
75.80
5.51
76.57
5.07
.77
2.25
.071
Lower Incisor
72.45
5.50
74.62
4.77
2.17
2.19
.000*
Na to Me
122.81
8.45
126.42
7.98
3.61
2.63
.000*
*P < .01
30
In Figure 3.3 below it shows the combined horizontal
and vertical changes for the upper and lower incisors and
lips from T1 to T2.
Tooth and Lip Movement
0
Vertical Change
-5
-4
-3
U1
-2
-1
0
-1
LL
UL
-2
L1
-3
Horizontal Change
Figure 3.3. Combined horizontal and vertical changes in mm
for the upper and lower incisors and lips from T1 to T2.
31
Angular Measurements
Results for each of the angular measurements from T1
to T2 showed a statistically significant difference.
The
IMPA and U1 to SN angles both showed a significant
decrease.
The interincisal angle of U1 to L1 showed a
significant increase.
Details are given below in Table
3.3.
Table 3.3.
Changes in cephalometric angular measures
Angular Measures
Time
Variable
T1
T2
Mean Change
Mean
SD
Mean
SD
Mean
SD
Sig.
IMPA
96.75
4.94
90.02
4.62
-6.74
4.07
.000*
U1 to SN
105.3
6.15
99.38
5.62
-5.93
8.47
.001*
U1 to L1
121.62
7.59
134.24
6.19
12.62
9.81
.000*
*P < .01
32
Linear Regression Analysis
Linear regression analyses were run to predict the
amount of lip change based on the amount of incisor
retraction and to evaluate the strength of these
correlations.
The results showed statistically significant
correlations.
Details are given below in Table 3.4.
There
was a correlation of r=.619 for the retraction of the upper
incisor to the upper lip with a mean ratio of 2.1:1.
The
correlation for the retraction of the lower incisor to
lower lip was r=.874 with a mean ratio of 1.1:1.
Scattergrams were constructed to show the linear
relationship between these variables.
See Figures 3.4 and
3.5.
Table 3.4: Relationship between incisor retraction and
subsequent lip change
Standard
Mean
Regression
Ratio
Coefficient
Independent
Variable
Dependent
Variable
Upper Incisor
Retraction
Upper Lip
Change
.619*
2.1:1
.361
Lower Incisor
Retraction
Lower Lip
Change
.874*
1.1:1
.755
Upper Incisor
Retraction
Lower Lip
Change
.682*
1.7:1
.445
Lower Incisor
Retraction
*p < .01
Upper Lip
Change
.796*
1.4:1
.620
33
Adjusted
R Square
Upper lip retraction
9
8
7
6
5
4
3
2
1
0
-1
-2
-1
0
1
2
3
4
5
6
7
8
9 10 11 12
Upper incisor retraction
Figure 3.4. Scattergram of upper incisor to upper lip
retraction for each subject in the study.
10
9
Lower lip retraction
8
7
6
5
4
3
2
1
0
-1
-2
-1
0
1
2
3
4
5
6
7
8
Lower incisor retraction
Figure 3.5. Scattergram of lower incisor to lower lip
retraction for each subject in the study.
34
Discussion
Previous studies in the literature have examined the
effects that extractions have on the soft tissue facial
profile.
In these studies it has been documented that
extractions cause a general reduction in lip protrusion or
flattening of the facial profile.
This present study aimed
to investigate the effects that the specific extraction
pattern of four first premolars would have in a sample of
Caucasian adolescent patients that began treatment with
minimal crowding and an Angle Class I molar occlusion.
These are patients that perhaps would not have extractions
if it weren’t for some other reason such as excessive lip
protrusion or excessive incisor proclination.
It might be
expected that perhaps in these extraction cases there would
be a greater potential for incisor retraction and resultant
reduction in lip protrusion.
However, on the other hand,
maybe the results would simply mirror the results from
other extraction studies.
The results from this present study did demonstrate a
significant reduction in the horizontal position of both
the upper lip (-2.37 mm) and lower lip (-2.89 mm), and the
upper incisor (-4.95 mm) and lower incisor (-3.28 mm).
Hanson’s results17 from a thesis at Saint Louis University
35
for the same extraction pattern of four first premolars
were much less.
In her study, the reduction for the upper
and lower lip was -1.21 mm and -.82 mm, and for the upper
and lower incisor was -2.25 mm and -.45 mm respectively.
It should be noted that in the present study just as
in many other extraction studies, the anchorage protocol
for the molars was not considered. Anchorage loss of the
molars during treatment could affect the total amount of
incisor and lip retraction that can occur.
Accounting for
the amount of anchorage loss of the molars is something
that could be incorporated into a future study.
It might also be noted that in this study
magnification differences were accounted for by equalizing
the distance between Sella and Nasion for the pre- and
post-treatment cephalograms.
This can help minimize the
effect that growth has on the measurement of the difference
between the variables from T1 and T2.
There was a marked reduction in the facial profile in
the present study as was demonstrated by the significant
retraction of the upper and lower lips to the E-plane of 2.8 mm and -3.5 mm respectively.
A comparison of these
results to those from previous studies is summarized in
Table 3.5.
36
Table 3.5. Comparison of change in lip position to E-Plane
following premolar extraction in previous studies compared
with the present study
Investigator
Lip Change
Upper Lip
Lower Lip
Kocadereli2
-1.0
-1.1
Drobocky and Smith3
-3.4
-3.6
James4
-3.3
Bishara et al5
-3.7
-3.4
Paquette et al6
-3.1
Luppanapornlarp et al7
-2.9
Bravo8
-3.4
Bowman and Johnston1
-3.8
-2.5
Luecke and Johnston9
-2.4
-1.4
Current Study
-2.8
-3.5
The current study’s results were very comparable to
those of the other studies.
The studies by Kocadereli2,
Drobocky and Smith3, and Bishara et al5 specifically limited
their samples to extractions of four first premolars also.
When compared to these studies, the results were very
similar with the exception of the study by Kocadereli which
had much less reduction in lip protrusion than the current
study.
Also, when James4 broke down his study by group,
four first premolar extractions showed a reduction in the
37
lower lip to E-plane of -3.77 mm which compares to the -3.5
mm in the present study.
Several authors have attempted to quantify a ratio for
the amount of lip retraction to incisor retraction that
occurs during orthodontic treatment.
They have done this
with hopes to effectively predict how the soft tissues will
respond to retraction of the teeth.
In the present study,
a mean ratio for the retraction of upper incisor to upper
lip was 2.1:1, and for retraction of the lower incisor to
the lower lip was 1.1:1.
The comparison to other studies
is summarized in Table 3.6.
Table 3.6. Comparison of the effects of incisor retraction
on the upper and lower lip in previous studies with the
present study
Investigator
Ratio
U1 : U Lip
L1 : L Lip
Rudee10
2.9 : 1
0.6 : 1
Roos11
2.5 : 1
1.0 : 1
Garner12
3.6 : 1
1.0 : 1
Lo and Hunter13
2.5 : 1
Waldman14
3.8 : 1
Perkins and Staley15
2.2 : 1
Kasai16
2.4 : 1
Hanson17
2.0 : 1
1.3 : 1
Current Study
2.1 : 1
1.1 : 1
38
The ratio of the present study for the lower incisor
to lower lip is very similar to that of previous studies.
A 1:1 ratio has been pretty consistent among studies.
The
ratio for the upper incisor to upper lip varies more among
studies ranging from 2:1 to 3.8:1.
The current study of
2.1:1 compares closely with Hanson17, Perkins and Staley15,
Kasai16, Lo and Hunter13, and Roos.11
Through the use of linear regression analysis we can
also compare the correlation values from this study to
previous studies.
Correlation for retraction of the upper
incisor to upper lip was r=.619 and for the lower incisor
to lower lip was r=.874.
In Hanson17 these values were
r=.70 and r=.73 respectively.
Rudee10 also showed similar
correlations to this of r=.73 and r=.70.
Roos11 showed less
correlation for the upper incisor to upper lip (r=.42) than
for the lower incisor to lower lip (r=.82).
Bloom18 showed
very strong correlations for both of r=.87 and r=.93
respectively.
The present study is similar to many of the
studies in that there is a stronger correlation between the
retraction of the lower incisor to lower lip than there is
for the upper incisor to lower lip.
There appears to be more variability for the upper lip
retraction.
Talass et al19 attributes this to the complex
anatomy and dynamics of the upper lip which is suspended
39
from the nose and the anterior nasal spine.
Burstone20 and
Oliver21 also believed that lip thickness and lip strain had
an effect on the variability of lip retraction.
Angular measurements from this study showed an average
decrease in the IMPA of -6.74 degrees and a decrease in the
U1 to SN of -5.93 degrees.
These decreases resulted in an
increased interincisal angle of 12.6 degrees.
These
results compare to other extraction studies that show a
significant retroclination of incisors.
40
Conclusions
According to the results of this study we may conclude
the following:
1. Upper and lower lip protrusion was reduced resulting
in an overall flattening of the facial profile.
2. There was a moderate correlation between retraction of
the upper incisors and corresponding upper lip
retraction, but there was an even stronger correlation
between retraction of the lower incisors and
subsequent lower lip retraction.
3. Upper and lower incisor proclination was reduced
during treatment which resulted in an increased
interincisal angle.
4. Further studies could be done to explore the effect
that molar anchorage has on the amount of incisor and
lip retraction.
41
Literature Cited
1. Bowman SJ, Johnston LE, Jr. The esthetic impact of
extraction and nonextraction treatments on Caucasian
patients. Angle Orthod. 2000;70:3-10.
2. Kocadereli I. Changes in soft tissue profile after
orthodontic treatment with and without extractions. Am
J Orthod Dentofacial Orthop. 2002;122:67-72.
3. Drobocky OB, Smith RJ. Changes in facial profile during
orthodontic treatment with extraction of four first
premolars. Am J Orthod Dentofacial Orthop.
1989;95:220-30.
4. James RD. A comparative study of facial profiles in
extraction and nonextraction treatment. Am J Orthod
Dentofacial Orthop. 1998;114:265-76.
5. Bishara SE, Cummins DM, Jakobsen JR, Zaher AR.
Dentofacial and soft tissue changes in Class II,
division 1 cases treated with and without extractions.
Am J Orthod Dentofacial Orthop. 1995;107:28-37.
6. Paquette DE, Beattie JR, Johnston LE, Jr. A long-term
comparison of nonextraction and premolar extraction
edgewise therapy in "borderline" Class II patients. Am
J Orthod Dentofacial Orthop. 1992;102:1-14.
7. Luppanapornlarp S, Johnston LE, Jr. The effects of
premolar-extraction: a long-term comparison of
outcomes in "clear-cut" extraction and nonextraction
Class II patients. Angle Orthod. 1993;63:257-72.
8. Bravo LA. Soft tissue facial profile changes after
orthodontic treatment with four premolars extracted.
Angle Orthod. 1994;64:31-42.
9. Luecke PE, 3rd, Johnston LE, Jr. The effect of maxillary
first premolar extraction and incisor retraction on
mandibular position: testing the central dogma of
"functional orthodontics". Am J Orthod Dentofacial
Orthop. 1992;101:4-12.
10. Rudee DA. Proportional profile changes concurrent with
orthodontic therapy. Am J Orthod. 1964;72:165-75.
42
11. Roos N. Soft-tissue profile changes in Class II
treatment. Am J Orthod. 1977;72:165-75.
12. Garner LD. Soft-tissue changes concurrent with
orthodontic tooth movement. Am J Orthod. 1974;66:36777.
13. Lo FD, Hunter WS. Changes in nasolabial angle related
to maxillary incisor retraction. Am J Orthod.
1982;82:384-91.
14. Waldman BH. Change in lip contour with maxillary
incisor retraction. Angle Orthod. 1982;52:129-34.
15. Perkins RA, Staley RN. Change in lip vermilion height
during orthodontic treatment. Am J Orthod Dentofacial
Orthop. 1993;103:147-54.
16. Kasai K. Soft tissue adaptability to hard tissues in
facial profiles. Am J Orthod Dentofacial Orthop.
1998;113:674-84.
17. Hanson RA. Incisor retraction and lip response with
various extraction patterns in caucasian females.
Saint Louis: Saint Louis University; 2003.
18. Bloom LA. Perioral profile changes in orthodontic
treatment. Am J Orthod. 1961;47:371-9.
19. Talass MF, Talass L, Baker RC. Soft-tissue profile
changes resulting from retraction of maxillary
incisors. Am J Orthod Dentofacial Orthop. 1987;91:38594.
20. Burstone CJ. Lip posture and its significance in
treatment planning. Am J Orthod. 1967;53:262-84.
21. Oliver BM. The influence of lip thickness and strain on
upper lip response to incisor retraction. Am J Orthod.
1982;82:141-9.
43
Appendix
Table A.1. Landmarks and Definitions
Abbreviation
Go
Landmark
Gonion
L1
LL
Mandibular
Incisor
Incisal
Edge
Mandibular
Central
Incisor
Apex
Lower Lip
Me
Menton
N
Nasion
Pog’
Prn
Soft Tissue
Pogonion
Pronasale
S
Sella
U1
Maxillary
Incisor
Incisal
Edge
Maxillary
Central
Incisor
Apex
Upper Lip
L1a
U1a
UL
Definition
The most convex point along the
inferior border of the ramus
The incisal tip of the mandibular
central incisor
The root tip of the mandibular
central incisor
The most anterior part of the
lower lip
The most inferior midline point
on the symphyseal outline of the
mandible
The most anterior point of the
frontonasal suture
The most anterior point on the
contour of the chin
Most anterior point on the nasal
tip
The center of the pituitary fossa
The incisal tip of the maxillary
central incisor
The root tip of the maxillary
central incisor
The most anterior point on the
upper lip
44
VITA AUCTORIS
Daniel Joseph Cloward was born in Salt Lake City, Utah
on September 23, 1976 to Raymond Lavar Cloward and the late
Linda Yates Cloward.
He grew up in Magna, Utah and attended Cyprus High
School.
After high school, he attended Ricks College in
Rexburg, Idaho for one year.
Then he lived in Santiago,
Chile for two years as a missionary for the Church of Jesus
Christ of Latter-Day Saints.
After returning home, he
attended Brigham Young University where he received a
Bachelor in Science degree in Sociology in 2000.
Daniel then worked for a few years in the Social Work
field before continuing his education at the University of
Louisville, where he received a Master of Public Health
degree in 2007 and a Doctor of Dental Medicine degree in
June of 2011.
He then attended the Orthodontic residency
program at Saint Louis University, where he plans to
complete his Master of Science in Dentistry degree in
December 2013.
Daniel is married to his wife Heather, and they have
four children.
45