Download Christopher Michael Ruth, D.D.S. Saint Louis University in Partial Fulfillment

RELATIONSHIP OF RAPID MAXILLARY EXPANSION STABILITY AND
INITIAL PALATAL VAULT HEIGHT
Christopher Michael Ruth, 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
2014
COMMITTEE IN CHARGE OF CANDIDACY:
Associate Professor Ki Beom Kim,
Advisor and Chairperson
Associate Clinical Professor Patrick Foley
Associate Clinical Professor Donald R. Oliver
i
DEDICATION
This work is dedicated to my parents who have been
strong supporters of my educational journey to become an
orthodontist. Their support has been invaluable as they
have lent their wisdom throughout this path I have chosen.
Your words of encouragement aided me when I wavered, your
advice strengthen my resolve. You have always chosen to put
your children first and I will always remember your words
and actions throughout my days as I strive to continue
being a better person each day. You love and support has
known no bounds. Thank you and I love you.
To my friends and faculty of Saint Louis University’s
Orthodontic Program. Every day has been an eye opening
experience, learning and striving to become a better
orthodontist. Thank you for your guidance and friendships,
these experiences will be carried with me throughout my
life.
ii
ACKNOWLEDGEMENTS
This project is only possible with the aid of the
following:
Dr. Ki Beom Kim, my advisor, you have been
instrumental for your guidance on shaping my thoughts and
designs for this project into a workable project. Your
academic and clinical teachings are invaluable. Thank you
for sharing your knowledge.
Dr. Donald Oliver, your patience and wisdom are
critical for the development of this thesis. Your impact
extends far beyond this project. The dedication and
commitment to this program has been invaluable for shaping
my residency experience.
Dr. Patrick Foley, your clinical and private practice
experience has provided great insights into the different
facets of orthodontics. I greatly appreciate your time and
aid in the shaping of this work.
To everyone that has made CADE a wonderful place the
last few years. My experience would be greatly diminished
without everyone’s presence.
iii
TABLE OF CONTENTS
List of Tables......................................... v
List of Figures........................................vi
CHAPTER 1:
INTRODUCTION............................... 1
CHAPTER 2:
REVIEW OF THE LITERATURE
History of Palatal Expansion............ 4
Indications for Palatal Expansion....... 5
Types of Expansion Appliances........... 6
Skeletal Effects of Palatal Expansion... 8
Dental Effects of Palatal Expansion.....10
Palatal Width...........................11
Palatal Height Measurements.............12
Palatal Height..........................15
Soft Tissue Effects.....................17
Long-Term Stability.....................18
Summary and Statement of Thesis.........19
Literature Cited........................21
CHAPTER 3:
JOURNAL ARTICLE
Abstract................................26
Introduction............................28
Materials and Methods...................30
Sample...............................30
Methodology..........................31
Statistical Analysis.................37
Reliability..........................37
Results.................................38
Discussion..............................40
Conclusions.............................43
Literature Cited........................45
Vita Auctoris..........................................48
iv
LIST OF TABLES
Table 3.1:
Landmarks and Definitions...............35
Table 3.2:
Lines and Definition....................36
Table 3.3:
Linear regression values measuring the
significance of the palatal vault height
to the intermolar widths................38
Table 3.4:
Average palatal vault height and intermolar
widths at time points T1, T2, T3 ..........38
Table 3.5:
Difference in average palatal vault height
and intermolar widths at time points T1, T2,
T3 ......................................39
v
LIST OF FIGURES
Figure 3.1:
Landmarks identified in
Orthoanalyzer™ and used to construct
intermolar lines........................33
Figure 3.2:
Intermolar lines constructed between
identified landmarks in
Orthoanalyzer™ to obtain intermolar
width measurements......................33
Figure 3.3:
Palatal vault heights created in
Orthoanalyzer™..........................34
vi
CHAPTER 1: INTRODUCTION
Rapid palatal expansion (RPE) is a commonly employed
technique used to address maxillary transverse deficiency.
Though introduced by E.H. Angle in The Dental Cosmos, it
did not gain wide spread acceptance until decades later.1 As
a useful technique to address crossbites and constricted
arches, there is concern about the stability of such dental
and skeletal movement.2 The literature has focused on the
types of expansion appliances that affect the stability as
well as the timing of such orthodontic intervention.
However, there is no method to predict the success of
expansion stability using factors that can be observed
prior to treatment from dental casts.
If such factors can be identified prior to treatment
and assessed then a clinician can utilize the information
to achieve a desired orthodontic outcome. In addressing a
deficient transverse maxilla, a clinician can benefit for
the knowledge of how much expansion is appropriate to
correct for a constricted maxilla.3 Additionally, the
knowledge of the amount of expansion required to correct a
constricted maxilla, needs to account for any potential
relapse that will counter the efforts of expansion. If an
identifiable factor can be used to assess the amount of
1
expansion needed to correct and maintain the desire
results, the clinician will not need to spend additional
time and effort addressing a relapse in the transverse
dimension.
Accounting for potential relapse, clinicians often
over expand or allow for longer retention following
expansion.4 These methods will potentially add to treatment
time, as excessive buccal overjet from overexpansion will
require fixed appliance to create interdigitated occlusion.
While a longer post-expansion retention adds more treatment
time before fixed appliances can be placed.3
Muscular forces may attribute to the stability or lead
to the relapse of orthodontic treatment.5 Forces directed
from the lingual or palatal surfaces of the dentition may
supply sufficient force aid in the stability of maxillary
expansion by counteracting the force from the buccal
muscles.6 The tongue, being the predominant muscle acting
against the lingual or palatal surfaces of the dentition
may be this stabilizing influence.7 For the tongue to aid in
the maxillary expansion, it will need to rest high in the
palate against the dentition and alveolar processes.5 A
constricted palate with an initially high palatal ceiling
may provide the tongue with an appropriate resting place to
2
aid in the expansion stability. Whereas, an initially lower
palate constricted palate already benefits from the force
of the tongue and expansion may cause greater cheek muscle
force with diminishing tongue force to balance.6 Following
expansion, more transverse room will allow for the tongue
to be positioned in a higher palatal depth. This change in
the equilibrium may contribute to the stability of the
maxillary expansion.7
The purpose of this study is to determine if there is
a relationship to the stability of rapid palatal expansion
and the initial palatal vault height.
3
CHAPTER 2: REVIEW OF THE LITERATURE
History of Palatal Expansion
Throughout orthodontic history, numerous themes recur
on patients’ problem lists. Among the reoccurring themes
that are present in orthodontic patients, decreased
maxillary skeletal transverse dimension has been addressed
since the beginning of noted orthodontic history.8 Angle
first proposed the use of palatal expanders in a 14-yearold female patient in Dental Cosmos.
This case study
reported that the midpalatal suture was successfully
separated to achieve the correction.9 For years, this was
met with skepticism. It was not until the advent of dental
radiology verifying the opening of the palatal suture that
palatal expanders gained wide-spread acceptance. Korkhaus
showed his successfully treated rapid palatal expander
(RPE) records with dental radiographs to the orthodontic
department of University of Illinois.10 Among those who were
intrigued by his claims, Brodie and Haas, eventually
reintroduced RPE to the United States where it has gained
widespread acceptance.3
In the Haas 1958 animal study, it was reported that:
(1) The procedure was apparently pain free. (2) The
midpalatal suture offered very little resistance to
4
spreading. Suture openings of 15mm in two weeks time were
recorded.3 The mandibular teeth without treatment, uprighted
or expanded probably in response to altered forces of
occlusion and change in muscle balance.11 Intranasal width
was increased. Changes up to 7mm were recorded.12
Indications for Palatal Expansion
Maxillary transverse deficiency often manifests in
different ways. The most common indication for rapid
palatal expansion is when there is dental unilateral or
bilateral crossbite. Other indicatons that do not manifest
crossbites include skeletal constriction with dental
compensation from accentuated Curve of Wilson resulting
from labial crown torque on the maxillary posterior teeth.
In addition, there may be an absence of dental crossbite if
both dental arches are constricted resulting in crowding.
Another possibility is a patient in Class II or Class III
malocclusion who may appear to be without crossbite until
the case is placed into Class I occlusion.11
Crossbites can occur in the deciduous dentition with
7% of children age 3 to 9 with the transverse deficiency.13
If not corrected then the problem may continue into the
mixed and permanent dentition. Treatment of the crossbite
can aid in the development of normal occlusion and when
5
used in the mixed dentition, helps create space for
developing teeth.14 Maxillary constriction should be
corrected early to remove potential asymmetrical growth.13
Types of Expansion Appliances
Maxillary expansion is accomplished through two
methods, skeletal and dental expansion. Numerous designs
have been fabricated to typically address the transverse
deficiency through skeletal movements while minimizing
dental expansion. Expanders can be separated into
appliances that are tooth borne, tissue borne, or a
combination of both.15
Tooth borne expansion is commonly accomplished with a
Hyrax expander. This device utilizes two to four bands to
the maxillary molars and most often the first maxillary
premolar or first deciduous molars connecting to a
jackscrew placed in the center of the palate. A quad-helix
and w-Arch are tooth borne appliances that expand without
the use of the jackscrew. Instead, the appliance is
expanded prior to insertion. Without the jackscrew, the
quad-helix and w-arch achieve dental tipping because of
lower force loads instead of the combined skeletal and
dental affect from the Hyrax.16 To remove occlusal
interferences, commonly in the mixed dentition, a bonded
6
expander may be used. Acrylic covers the posterior teeth in
each maxillary posterior sextant, allowing for coverage and
removes occlusal interferences in the dentition. This
design also utilizes a jackscrew for the separation force.17
The Haas expander is a common combined tooth-tissue
borne expander. The design uses bands on four teeth, a
soldered arm that connects the abutment on each side of the
arch, and in addition, there is acrylic to either side of
the jackscrew, allowing for the distribution of the
expander force to the tissue. The result is thought to be
less dental effect and more skeletal movement.3
Recently, interest in tissue borne expanders have been
explored with the advent of mini-screw implants (MSI).
Using the MSI on either side of the palatal suture, an
acrylic based expander is attached either with resin or
abutment caps. This allows for greater orthopedic movement,
as there is no direct force against the dentition.18
Recent literature has challenged the Haas expanders’
results. It was found that the Haas expander resulted in
more significant dental tipping of the posterior teeth.19
The Haas expander resulted in 3.6°, 7.5°, and 3.5° of
buccal inclination change of the 1st bicuspid, 2nd bicuspid,
and 1st molar respectively. Whereas the Hyrax expander only
7
experienced significant inclination change of the 2nd
bicuspid, 5.9°, and non-significant changes to the 1st
bicuspid, 0.9°, and the 1st molar, 1.6°.19 Instead, the
authors claim that the Hyrax creates more orthopedic
movement as a tooth borne appliance compared to the toothtissue borne Haas expander.15 This can be attributed to the
acrylic covered appliances having more flexibility
resulting in the dental tipping.20
Skeletal Effects of Palatal Expansion
The orthopedic movement of palatal expansion occurs
when the midpalatal suture separates after sufficient
tension has built up overcoming the interdigitation of the
midpalatal suture. This is possible if the suture has not
been calcified beyond the threshold for orthopedic movement
in palatal expansion. Most patients are able to undergo
successful palatal expansion up to age 17 when
calcification and interdigitation of the midpalatal suture
resists the orthopedic movement of palatal expansion.21 From
histological exams, the midpalatal suture is smooth and
broad during the infantile stage prior to age 10.
Development continues into overlapping sections as a
squamous suture by age 13, called the juvenile stage.
Increased interdigitations of the adolescent stage results
8
in overlapping projections from both halves of the palate
by age 14. Finally, the suture forms numerous bony bridges
and synostoses in the adult stage.22 This results in lateral
displacement of the two halves of the palatal bone. This
movement is not linear, instead greater separation in the
anterior results in a diastema opening between the
maxillary central incisors.23
In addition to the orthopedic movement from the
midpalatal suture, the alveolar processes are forced
laterally, through the force directed through either the
dentition or tissue borne appliance resulting in flexing of
the alveolar process. Claims of less dental tipping and
alveolar bending with greater orthopedic movement occur in
rapid expansion.24 The nasal cavity also widens creating
greater nasal respiration from the maxilla’s displacement
in the inferior and anterior direction.21,
25
Because of the
pyramidal shaped opening with the apex at around the
frontal-maxillary suture, greater expansion is noted at the
occlusal plane when compared to the palatal plane.23
Calcification of the midpalatal suture takes up to 90 days
following suture opening.3 Slow expansion has been reported
to allow for better suture calcification following
expansion.24
9
In response to the changes in the maxilla, the
mandible responds by rotating downward, opening the
mandibular plane potentially creating or worsening an
openbite.21 This results in improvement with Class III
patients and worsening of Class II patients.3 Conversely,
there are disputed claims that Class II patients can become
Class I following palatal expansion.14
However, Lagravere et al. showed in their systematic
review that no statistically significant changes were noted
anterior-posterior for the maxilla or mandible. In
addition, the only vertical significant findings were found
by cephalometric measurements. The mandibular plane in
response to expansion was only reduced by 0.85° compared to
reduction in mandibular plane of the control group , 2.21°,
and the fixed appliance group, 2.52°.26
Dental Effects of Palatal Expansion
Whether desired or not, dental effects are noticed
following rapid palatal expansion. While orthopedic
separation through the separation of the midpalatal suture
is desired, Garrett et al. showed in 30 consecutive
patients treated with hyrax expanders, alveolar bending and
dental tipping are a common result with 13% of the former
and 49% of the later resulting in molar expansion.27
10
Additional dental effects include a diastema,
increased overjet, decreased overbite and mandibular
posterior uprighting.28 The most readily noticeable dental
effect, the diastema, results from the midpalatal suture
opening through the maxillary central incisors. The average
diastema opens 4 mm but closes due to the transeptal fibers
connecting the central incisors.23 The mandible changes in
response to the occlusal interference between the maxillary
and mandibular arches. It is noted that banded RPEs
coincide with mandibular expansion, while bonded RPEs lack
this mandibular change.29 The increase in the mandibular
arch from palatal expansion is considered stable.30
Palatal Width
Utilizing dental casts, palatal expansion can be
measured from either the cusp tips of contralateral teeth
or central fossa. It is reported that the amount of dental
change ranges accounts up to 16% to 30% of the total
expansion.31
For untreated children age 6 to 14, the maxillary
width was noted for the posterior teeth. The intercanine
width increased from 25.64 mm to 26.46 mm and the first
bicuspid increased from 28.27 mm to 29.06 mm both with 0.10
mm a year change. While the second bicuspid and first molar
11
noted greater yearly change of 0.27 mm and 0.33 mm a year
as they increased 32.84 mm to 35.00 mm and 33.93 mm to
36.55 mm respectively.32
Reports of maxillary expansion in unilateral posterior
crossbites show increased width in the maxillary
intercanine by 4.5 mm and intermolar change of 3.5 mm.
These measurements were performed in the mixed dentition at
age 7 years, 7 months with post-expansion measurements
taken at age 8 years and 8 months on average. The slow
expansion was achieved by one 0.25mm turn every other day
with a Haas expander. Four years later the canine showed
98% retention of expansion and the molar retained 80% of
the initial expansion.33
Palatal Height Measurements
Palatal vault height can be measured using dental
casts, cephalometrics or cone beam computed tomography
(CBCTs). Virtual casts can be positioned in xyz-coordinate
system. The xy-plane will be parallel to the occlusal plane
and the y-axis follows the estimated midpalatal suture.
Using the tip of the incisive papilla as a reference point
for different time points, the casts can be rotated to
match the coordinate planes of each other for comparison.
Palatal vault heights can be defined as straight lines that
12
connect the deepest points of the palatal vault to the
occlusal plane from cross sections between the contact
points of posterior teeth.34
Using dental casts, standardized photographs from the
posterior surfaces can be used to view palatal vault
height. A straight line connecting the palatal cervical
lines of the contralateral maxillary second primary molars
are used as the x-axis on xy-coordinate system. A straight
vertical line, perpendicular to the x-axis passing through
the midpalatal raphe is the y-axis. From this line, the
palatal height is measured. The midpalatal raphe near the
primary second molars is used as it’s near the highest
point of the palate and easily identifiable in the primary
dentition.35
Boundaries for the palate can be set using the
gingival plane, created by connecting the midpoints of the
dentogingival junction of the primary or permanent teeth.
The distal plane can be created using the distal surface of
the contralateral terminal teeth that is perpendicular to
the gingival plane. This method is useful when using the
distal plane for the palatal vault height measurement or
when measuring the palatal volume.36
13
An additional method has been used to create a
gingival plane for palatal vault height to define the most
cervical point of the palatal dentogingival junction using
a least square algorithm. The resulting three vectors
created between the each of the posterior teeth has been
divided into four equal sections with 12 total dividing
points. From these dividing points, perpendicular lines to
the palate were used to measure the height.37 In addition,
the palatal rugae were used for the anterior region of the
palate. The rugae have been reported to be stable and
reproducible landmarks.38 The three most anterior rugae were
chosen, measuring the medial and lateral points of each.
Perpendicular lines from these points were measured to the
gingival plane.37
Using lateral cephalometrics, the palatal vault height
can be measured using the highest point in the palatal
vault area regardless of AP position or the height at a
fixed location AP at the palatal root of the first molars.
Both methods used the superior border of the hard palate as
one point, drawing a line to a line parallel to the
Frankfort plane that goes through the CEJ of the central
incisor.39
14
Palatal Height
For untreated cases in children age 6 to 14,
significant annual increases in all measurements of palatal
height were noted with greater increases at the lateral of
the palate near the alveolar bone. No significant sexual
differences in growth pattern were noted though the males
had deeper palates. On average, the median of the
intermolar height increased from 10.32 mm to 13.87 mm with
0.44 mm increased per year. The intercanine height
increased 3.47 mm to 4.94 mm with 0.18 mm annual increase.
The first bicuspid changed from 8.24 mm to 9.94 mm with
0.21 mm increase while the second bicuspid increased from
11.19 mm to 13.54 mm with a 0.29 mm annual increase.32
Differences are noted in the primary dentition of the
palatal vault. In children age 4 to 5, there is no
difference in the palatal vault depth and the primary
second molar angulation. Little difference is noted between
right and left halves of the palatal. For boys, the palatal
height is 10.77 mm and 10.67 mm in females at age 4 to 5.
Instead, differences were noted in girls with narrower
maxillary arch width than boys.35
Early expansion theory, indicated that palatine
processes were lowered due to the expanding alveolar
15
process, thus RPEs caused lower palatal vault height by
lowering the “roof”.25 Later studies found that the palatal
vault height remained constant or was elevated during
growth with no relationship on intermolar width and
height.40
Conflicting reports show that either flattening of the
palate or no vertical changes in height between the first
molars.41 Other reports indicate that increases in palatal
height following RPE between the first bicuspids to be as
large as 2.3 mm, likely from growth and dental eruption.
Such inconsistent results suggest that the patients’ age or
methodology design attribute to the differing results.31
Rapid palatal expansion utilizing bonded RPEs in the
mixed dentition resulted in half a millimeter reduction in
palatal height following 6 months of expansion and
retention with appliance between the primary second
molars.34
When using the occlusal plane as a reference, the
palatal height between the first molars at the midpalatal
suture of 8 year olds pre-expansion was noted as 17.6 mm.
Following expansion, the height decreased to 17.0 mm but
after one year increased to pre-expansion levels of 17.7
mm. The two year retention continued to increase to 18.3
16
mm. It is theorized that the lateral rotation of the
palatal segments may attribute to the immediate decrease in
vault height.42
The palatum osseum, the bony plate of the palate, has
been shown to grow as children age. One study shows that at
14 to 15, the palatal height is 11.8mm, 16 to 18 that
height increases to 13.0mm, as an adult the height reaches
13.8mm.43 Another study reports that the palatum osseum
height is 12.6mm in males and 12.1mm in females. Resulting
in a slight difference based on sex.44
In has been reported that, the palatal vault height is
affected by extraction orthodontic therapy. During
treatment all regions of the palate increase in height for
both extraction and non-extraction therapy. Following 2
years of active retention, decreases in the palatal vault
height between the canines and remaining bicuspids were
noted in the extraction patients 5 years after active
retention. Whereas non-extraction patients continued to
have an increased palatal vault height.22
Soft Tissue Effects
Anatomical changes of the palate following RPE produce
improved tongue activity during swallowing, chewing and
17
speaking.45 Iwasaki et al. shows that palatal expansion
raises the tongue posture. It is also reported that the
constricted maxillary arch may a result from a lower
initial tongue posture due to nasal obstruction and mouth
breathing.7 Ozbek et al. reported that expansion in
constricted maxillary arches without respiratory
disturbances, changes the low tongue posture.46 As proposed
by Moss, orthodontic stability is affected by a wide
variety of occlusal, periodontal, gingival and perioral
tissue forces creating an equilibrium.47 These forces change
through maxillary expansion, an increase in buccal pressure
on the maxillary molars with decreased tongue pressure on
the lingual surfaces has been reported.6 Other studies
report the tongue exerting a greater effect against the
dentition. In severe constriction, there is insufficient
space for the tongue to rest against the palate. After
expansion the tongue repositions to a higher posture,
creating balanced pressure in equilibrium with the cheek
muscles.5
Long-Term Stability
Palatal expansion stability is important to determine
the success of rapid palatal expansion. Apical base and
nasal cavity volume have been shown to be stable in thirty
18
two cases after one year of retention. In contrast, relapse
is noted within the dental arch.15 Later studies confirmed
that palatal expansion was stable up to three years posttreatment.30 Other studies note that up to 8 years later,
maxillary changes in expansion is stable.48 In contrast,
continued transverse increases are noted up to 5 years
post-treatment following expansion and fixed appliances in
the intermolar width with decreases in intercanine width.28
To prevent relapse that will clinically affect the
treatment result, expansion up to 10 mm to completely
encase the mandibular arch with the maxillary arch, is
used. This method allows for significant relapse to occur
while maintaining favorable intra-arch width.4
While palatal expansion is stable, 0.51 mm of relapse
is noted in the maxillary molar width of Class II patients
with Haas expanders and cervical pull headgear.49 Other
studies note that up to 8 years later there is significant
relapse in the mandibular arch length, perimeter and
intercanine width.48
Summary and Statement of Thesis
Rapid Palatal Expansion has gained widespread
acceptance since it has been reintroduced by Haas to
19
address maxillary transverse deficiencies.3 This tool has
been used for unilateral and bilateral crossbites to
correct constricted skeletal dimensions.11 Numerous designs
have been constructed to achieve certain skeletal or dental
effects often with both being affected. The literature has
focused on these appliances and the resulting stability in
retention.15 However, no conclusive results indicate that
data collected from initial records can be used to predict
the stability of retention. The purpose of this study is to
predict the rapid palatal expansion stability using the
initial casts’ palatal vault height.
20
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or adult teeth. Dental Cosmos 1860;540-4.
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Rapid maxillary expansion followed by fixed
appliances: a long-term evaluation of changes in arch
dimensions. Angle Orthod 2003;344-53.
3. Haas AJ. The treatment of maxillary deficiency by
opening the midpalatal suture Angle Orthod 1965;20017.
4. Haas AJ. Palatal expansion: just the beginning of
dentofacial orthopedics. Am J Orthod 1970;219-55.
5. Ohkiba T, Hanada K. Adaptive functional changes in the
swallowing pattern of the tongue following expansion
of the maxillary dental arch in subjects with and
without cleft palate. Cleft Palate J 1989;21-30.
6. Küçükkeleş N, Ceylanoğlu C. Changes in Lip, Cheek, and
Tongue Pressures After Rapid Maxillary Expansion Using
a Diaphragm Pressure Transducer. The Angle
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7. Iwasaki T, Saitoh I, Takemoto Y, Inada E, Kakuno E,
Kanomi R, Hayasaki H, Yamasaki Y. Tongue posture
improvement and pharyngeal airway enlargement as
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8. WR Proffit HF, DM Sarver. Contemporary Orthodontics. 4th
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9. Timms DJ. The dawn of rapid maxillary expansion. Angle
Orthod 1999;247-50.
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orthodontics at the University of Illinois. 1958.
11. McNamara JA. Maxillary transverse deficiency. Am J
Orthod Dentofacial Orthop 2000;567-70.
21
12. Haas AJ. Gross Reactions to the Widening of the
Maxillary Dental Arch of the Pig by Splitting the Hard
Palate. Thesis, University of Illinois. 1958.
13. Kutin G, Hawes RR. Posterior cross-bites in the
deciduous and mixed dentitions. Am J Orthod 1969;491504.
14. Gianelly AA. Rapid palatal expansion in the absence of
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Lima EM, Rizzatto SM. Immediate effects of rapid
maxillary expansion with Haas-type and hyrax-type
expanders: a randomized clinical trial. Am J Orthod
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16. Erdinc AE, Ugur T, Erbay E. A comparison of different
treatment techniques for posterior crossbite in the
mixed dentition. Am J Orthod Dentofacial Orthop
1999;287-300.
17. Reed N, Ghosh J, Nanda RS. Comparison of treatment
outcomes with banded and bonded RPE appliances. Am J
Orthod Dentofacial Orthop 1999;31-40.
18. Kim KB, Helmkamp ME. Miniscrew implant-supported rapid
maxillary expansion. J Clin Orthod 2012;608-12.
19. Garib DG, Henriques JF, Janson G, Freitas MR, Coelho
RA. Rapid maxillary expansion--tooth tissue-borne
versus tooth-borne expanders: a computed tomography
evaluation of dentoskeletal effects. Angle Orthod
2005;548-57.
20. Braun S, Bottrel JA, Lee KG, Lunazzi JJ, Legan HL. The
biomechanics of rapid maxillary sutural expansion. Am
J Orthod Dentofacial Orthop 2000;257-61.
21. Haas AJ. Palatal expansion: just the beginning of
dentofacial orthopedics. Am J Orthod 1970;219-55.
22. Primozic J, Perinetti G, Richmond S, Ovsenik M. Threedimensional longitudinal evaluation of palatal vault
changes in growing subjects. Angle Orthod 2012;632-6.
22
23. Wertz RA. Skeletal and dental changes accompanying
rapid midpalatal suture opening. Am J Orthod 1970;4166.
24. Bishara SE, Staley RN. Maxillary expansion: clinical
implications. Am J Orthod Dentofacial Orthop 1987;314.
25. Haas AJ. Rapid Expansion Of The Maxillary Dental Arch
And Nasal Cavity By Opening The Midpalatal Suture. The
Angle Orthodontist 1961;73-90.
26. Lagravere MO, Major PW, Flores-Mir C. Long-term
Skeletal Changes with Rapid Maxillary Expansion. The
Angle Orthodontist 2005;1046-52.
27. Garrett BJ, Caruso JM, Rungcharassaeng K, Farrage JR,
Kim JS, Taylor GD. Skeletal effects to the maxilla
after rapid maxillary expansion assessed with conebeam computed tomography. Am J Orthod Dentofacial
Orthop 2008;8-9.
28. Gurel HG, Memili B, Erkan M, Sukurica Y. Long-term
effects of rapid maxillary expansion followed by fixed
appliances. Angle Orthod 2010;5-9.
29. Miller CL, Araújo EA, Behrents RG, Oliver DR, Tanaka
OM. Mandibular arch dimensions following bonded and
banded rapid maxillary expansion. Journal of the World
Federation of Orthodontists 2014;119-23.
30. Lima AC, Lima AL, Filho RM, Oyen OJ. Spontaneous
mandibular arch response after rapid palatal
expansion: a long-term study on Class I malocclusion.
Am J Orthod Dentofacial Orthop 2004;576-82.
31. Ladner PT, Muhl ZF. Changes concurrent with orthodontic
treatment when maxillary expansion is a primary goal.
Am J Orthod Dentofacial Orthop 1995;184-93.
32. Yang ST, Kim HK, Lim YS, Chang MS, Lee SP, Park YS. A
three dimensional observation of palatal vault growth
in children using mixed effect analysis: a 9 year
longitudinal study. Eur J Orthod 2013;832-40.
23
33. Wong CA, Sinclair PM, Keim RG, Kennedy DB. Arch
dimension changes from successful slow maxillary
expansion of unilateral posterior crossbite. Angle
Orthod 2011;616-23.
34. Muchitsch AP, Winsauer H, Wendl B, Pichelmayer M,
Kuljuh E, Szalay A, Muchitsch M. Remodelling of the
palatal dome following rapid maxillary expansion
(RME): laser scan-quantifications during a low growth
period. Orthod Craniofac Res 2012;30-8.
35. Tsai HH, Tan CT. Morphology of the palatal vault of
primary dentition in transverse view. Angle Orthod
2004;774-9.
36. Primozic J, Baccetti T, Franchi L, Richmond S, Farcnik
F, Ovsenik M. Three-dimensional assessment of palatal
change in a controlled study of unilateral posterior
crossbite correction in the primary dentition. Eur J
Orthod 2013;199-204.
37. Heiser W, Niederwanger A, Bancher B, Bittermann G,
Neunteufel N, Kulmer S. Three-dimensional dental arch
and palatal form changes after extraction and
nonextraction treatment. Part 2. Palatal volume and
height. Am J Orthod Dentofacial Orthop 2004;82-90.
38. Almeida MA, Phillips C, Kula K, Tulloch C. Stability of
the palatal rugae as landmarks for analysis of dental
casts. Angle Orthod 1995;43-8.
39. Gohl E, Nguyen M, Enciso R. Three-dimensional computed
tomography comparison of the maxillary palatal vault
between patients with rapid palatal expansion and
orthodontically treated controls. Am J Orthod
Dentofacial Orthop 2010;477-85.
40. Linder-Aronson S, Lindgren J. The skeletal and dental
effects of rapid maxillary expansion. Br J Orthod
1979;25-9.
41. Gross reactions to the widening of the maxillary dental
arch of the pig by splitting the hard palate: By
Andrew J. Haas, University of Illinois, Chicago,
Illinois. American journal of orthodontics 1959;868-9.
24
42. Spillane LM, McNamara JA, Jr. Maxillary adaptation to
expansion in the mixed dentition. Semin Orthod
1995;176-87.
43. Redman RS, Shapiro BL, Gorlin RJ. Measurement of normal
and reportedly malformed palatal vaults. II. Normal
juvenile measurements. J Dent Res 1966;266-9.
44. Vidic B. Variations in height of the palatum osseum as
a function of other vertical dimensions and angles of
the skull. J Dent Res 1971;14-6.
45. Fried KH. Palate-Tongue Relativity. The Angle
Orthodontist 1971;308-23.
46. Ozbek MM, Memikoglu UTT, Altug-Atac AT, Lowe AA.
Stability of Maxillary Expansion and Tongue Posture.
The Angle Orthodontist 2009;214-20.
47. Moss JP. The soft tissue environment of teeth and jaws.
An experimental and clinical study: part 1. Br J
Orthod. 1980;127-37.
48. Moussa R, O'Reilly MT, Close JM. Long-term stability of
rapid palatal expander treatment and edgewise
mechanotherapy. Am J Orthod Dentofacial Orthop.
1995;478-88.
49. Lima Filho RM, de Oliveira Ruellas AC. Long-term
maxillary changes in patients with skeletal Class II
malocclusion treated with slow and rapid palatal
expansion. Am J Orthod Dentofacial Orthop 2008;383-8.
25
CHAPTER 3: JOURNAL ARTICLE
Abstract
Introduction: Rapid palatal expansion continues to be a
widespread and popular technique to correct maxillary
transverse discrepancies. Focus has been on how the
expander designs and treatment duration affect long-term
stability. Changes in the oral cavity affect the stability
of orthodontic treatment, including expansion.
Purpose:
The purpose of this study is to determine if palatal vault
height can be used as an indicator for the long-term
stability of rapid palatal expansion. Materials and
Methods: 56 patients underwent rapid palatal expansion with
the Haas expander design and fixed edgewise non-extraction
therapy. Dental cast records were taken at pre-treatment
(T1), post-treatment (T2), and long-term retention (T3).
The records were scanned and measured for intermolar widths
and palatal vault heights. Initial palatal vault heights
were measured along the midpalatal suture, between the
maxillary first molars and midway from the maxillary first
molars and the incisive papilla. Intermolar widths were
recorded at the lingual gingival margin and the centroid.
Linear regression assessed the significance of palatal
vault height as a predictor. Results: Intermolar width
26
increased from T1 to T2. There are no significant findings
for rapid palatal expansion relapse. Palatal vault height
continued to increase through all time points. No
significance was found between palatal vault height and the
relationship with rapid palatal expansion.
Conclusions: There is no relationship between initial
palatal vault height and rapid palatal expansion stability.
27
Introduction
Rapid palatal expansion (RPE) is a commonly employed
technique used to address maxillary transverse deficiency.
Though introduced by E.H. Angle in The Dental Cosmos, it
did not gain wide spread acceptance until decades later.1
Rapid palatal expansion has regained popularity as a useful
technique to address crossbites and constricted arches.
There is concern about the stability of such dental and
skeletal movement.2-6 Expansion is beneficial when there is
dental unilateral or bilateral crossbite or skeletal
constriction. At times, the skeletal constriction is missed
due to dental compensation or anterior-posterior
discrepancy hiding the obvious signs of dental crossbites.7
Developing normal occlusion and possibly relieving crowding
to counter future extractions may also be addressed by
expansion.8
The literature has focused on the expansion appliances
that affect the stability as well as the timing of such
orthodontic intervention.4-6,
9, 10
The patient’s age affects
the success of treatment, due to increasing resistance to
sutural separation.4,
7, 9-11
And there is conflicting
arguments regarding the stability of different expander
designs.5,
6, 10
However, there is no method to predict the
28
success of expansion stability using dental factors that
can be observed prior to treatment on dental casts.
Changes in the oral cavity can result in a different
equilibrium of forces.12 Forces that can be a benefit in
stability of maxillary expansion include increased lingual
pressure or decreased buccal pressure.13 The cheek muscles
exert greater force against the dentition when expansion
occurs, thus it may attribute to expansion relapse. A
stronger lingual force, presented by the tongue can provide
a new equilibrium to provide stability to expansion.12
In a constricted palate with a deep palatal vault
height, the tongue has a lower resting posture.13 Following
expansion, the tongue rises to a new resting posture
against the palate. This provides additional lingual force
to create a new equilibrium in oral forces against the
cheek muscles.14 The initial palatal vault height in a
constricted palate may be the dental factor that will aid
in assessing rapid palatal expansion stability.
The purpose of this study is to determine if there is
a relationship to the stability of rapid palatal expansion
and the initial palatal vault height.
29
Materials and Methods
Sample
The sample consisted of a collection of 56 subjects
with digitized dental casts at Saint Louis University
Center for Advanced Dental Education. The dental casts were
collected from a single private practice office, treated by
the same practitioner and scanned by the 3Shape R700™
scanner (Copenhagen, Denmark). The patients were treated
with palatal expansion using the Haas appliance. The Haas
expander used bands on the first molars and if present the
first bicuspids. An acrylic plate on both sides of the
jackscrew completed the tooth-tissue borne appliance. The
appliance was turned twice a day, 0.25 mm per turn until
the maxillary arch contained the mandibular arch. After 3
months of retention using the expander, the patients
underwent fixed edgewise appliances with non-extraction
therapy. After treatment, the patients received a maxillary
removable retainer and a mandibular bonded retainer from
canine to canine. These were worn for an average of 6.5
years.
Dental cast records were taken at three time points,
prior to expansion and treatment (T1), post-treatment
expansion and fixed appliances (T2), and long-term recall
30
(T3). The mean starting age was 12 years 3 months ± 2 years
5 months, treatment lasted until 16 years 0 months ± 3
years 11 months with long-term retention at 27 years 11
months ± 6 years 2 months. The retention protocol following
orthodontic treatment used a removable upper appliance and
a lower lingual fixed retainer from canine to canine. Each
were worn for an average of 6.5 years.15
Methodology
3Shape’s OrthoAnalyzer™ software (Copenhagen, Denmark)
was used to analyze the digitized casts. On each cast, 15
landmarks were chosen to create four measured lines and 5
supplemental lines (Table 3.1 and 3.2). The four landmarks
on each first molar were placed on the mesial and distal
marginal ridges and the buccal and lingual grooves. The
centroid defined as the midpoint created by the
intersection from two constructed lines was placed for each
maxillary first molar (Fig. 3.1). From the centroid of the
molar to its contralateral molar, the line right centroid,
left centroid (RCLC) was created to measure the intermolar
width (Fig. 3.2).
A second intermolar width was measured at the gingival
lingual margin (GLLine). The GLLine width was than compared
to the RCLC width to note if dental tipping occurred during
31
expansion (Fig 3.2). The landmarks for the measured line
were placed at the lowest gingival margin of the mesial
palatal cusp.
The palatal vault height was measured at two points
along the midpalatal suture from the incisive papilla to
the midpoint of the intermolar line GLLine. The first
measurement was taken along the palate between the first
maxillary molars; the second was taken halfway between the
first molars and the incisive papilla approximately between
the first bicuspids (Fig 3.3). For each measurement, the
distance was measure from a landmark on the palate to the
reference plane created by the gingival lingual margins of
the maxillary first molars and the incisive papilla.
The lines constructed by the landmarks measured the
intermolar widths and palatal vault heights to 0.01 mm.
These measurements were taken at the three time points.
32
Figure 3.1: Landmarks identified in OrthoAnalyzer™ and used to
construct intermolar lines. Right Mesial (RM), Right Buccal (RB),
Right Distal (RD), Right Lingual (RL), Right Centroid (RC) and
Right Gingival Lingual (RGL).
Figure 3.2: Intermolar lines constructed between
landmarks in OrthoAnalyzer™ to obtain intermolar
measurements. Right Centroid Left Centroid width
Lingual Line width (GLLine) and Incisive Papilla
33
identified
width
(RCLC), Gingival
(IP).
Figure 3.3: Palatal vault heights were created in OrthoAnalyzer™.
The palatal vault heights were measured along the midpalatal
suture. The measured distance originated from the plane created
by the gingival lingual margins and the incisive papilla. Palatal
Vault Height 6 (PVH6) the measurement between the maxillary first
molars, Palatal Vault Height Midpoint (PVHM) was measured midway
to the incisive papilla.
34
Table 3.1: Landmarks and Definitions
Abbreviation
Landmark
Definition
RM
Right mesial
Mesial marginal ridge midpoint on
right maxillary first molar
RB
Right buccal
Point on buccal groove of right
maxillary first molar on the
occlusal surface
RD
Right distal
Distal marginal ridge midpoint on
right maxillary first molar
RL
Right lingual Point on the lingual groove of
right maxillary first molar on the
occlusal surface
RGL
Right
Point most cervical on the mesial
gingival
palatal cusp of the right maxillary
lingual
first molar
RC
Right Center
The intersecting point of 2 lines
drawn between RM/RD and RB/RL
LM
Left mesial
Mesial marginal ridge midpoint on
left maxillary first molar
LB
Left buccal
Point on the buccal groove of left
maxillary first molar on the
occlusal surface
LD
Left distal
Distal marginal ridge midpoint on
left maxillary first molar
LL
Left lingual
Point on the lingual groove of left
maxillary first molar on the
occlusal surface
LGL
Left gingival Point most cervical on the mesial
lingual
palatal cusp of the left maxillary
first molar
LC
Left Center
The intersection of 2 lines drawn
between LM/LD and LB/LL
IP
Incisive
The midpoint of the incisive
Papilla
papilla
PVH6
Palatal Vault The height of the palatal vault
Height 6
along the midpalatal suture between
the first molars
PVHM
Palatal Vault The height of the palatal vault
Height
along the midpalatal suture between
Midpoint
the incisive papilla and the first
molar
35
Table 3.2: Lines and Definitions
Abbreviations
Line
GLLine
Line from RGL to LGL
RCLC
Line from RC to LC
PVH6Line
Line from Gingival
Plane to PVH6
PVHMLine
Line from Gingival
Plane to PVHM
RBL
Line from the RB to RL
RMD
Line from the RM to RD
LBL
Line from the LB to LL
LMD
Line from the LM to LD
36
Definition
Line measuring distance
between the gingival
lingual margins of
maxillary first molars
Line measuring distance
between the occlusal
centroids of maxillary
first molars
Line measuring the depth
of the palatal vault
height from the gingival
plane to the palatal
vault between the first
molars along the
midpalatal suture
Line measuring the depth
of the palatal vault
height from the gingival
plane to the palatal
vault along the
midpalatal suture halfway
from the first molar and
incisive papilla
Supplemental line between
the right buccal and
right lingual landmarks
to determine the right
centroid
Supplemental line between
the right mesial and
right distal landmarks to
determine the right
centroid
Supplemental line between
the left buccal and left
lingual landmarks to
determine the left
centroid
Supplemental line between
the left mesial and left
distal landmarks to
determine the left
centroid
Statistical Analysis
The null hypothesis of this study states the initial
palatal vault height cannot be used to predict rapid
palatal expansion stability. The measurements taken from
the digitized casts were recorded and organized in Excel
2010 (Microsoft Corp., Seattle, WA). To determine if the
null hypothesis was rejected, the linear regression was
calculated from the palatal vault height measurements, PVH6
and PVHM at T1. The intermolar changes of T3 from T2 were
calculated and compared to the palatal height measurements
with the linear regression analysis using a significance
level of p < 0.05. Paired t-test were used to determine the
significance of the variable change at the three different
timepoints with a p level < 0.05.
Reliability
To evaluate the reliability of the measurements, ten
percent of the total sample were randomly chosen and
measured. Cronbach’s alpha determined the reliability from
the six randomly chosen patients for each of the three
timepoints. The original measurements were assessed as
reliable as the intraclass correlations for each variable
were greater than 0.80.
37
Results
The linear regression analysis has determined that
null hypothesis failed to be rejected for PVH6 and PVHM
with both dependent variables, intermolar width
measurements RCLC and GLLine are reported in Table 3.3.
Average palatal vault heights and intermolar widths are
recorded in Table 3.4. Change in time points T1, T2, and T3
were measured and recorded in Table 3.5.
Table 3.3: Linear regression values measuring the significance of
the palatal vault height to the intermolar widths. Significance
is achieved when p < 0.05
Independent
Variable
Dependent
Variable
F Value
R Square
Adjusted R
Square
P
PVH6
GLLine
0.833
0.015
-0.003
0.365
PVH6
RCLC
0.117
0.002
-0.016
0.733
PVHM
GLLine
1.006
0.018
0.00
0.324
PVHM
RCLC
0.119
0.002
-0.016
0.732
Table 3.4: Average palatal vault height and intermolar widths at
time points T1, T2, T3.
T1
T2
T3
Variable
Mean ± SD
Mean ± SD
Mean ± SD
PVH6
12.90 ± 2.35
14.40 ± 1.96
15.07 ± 2.29
PVHM
10.94 ± 1.84
11.77 ± 1.75
11.86 ± 1.97
RCLC
42.22 ± 4.68
48.28 ± 2.38
48.12 ± 2.36
GLLine
28.99 ± 3.91
34.96 ± 2.19
35.19 ± 1.98
Units: millimeters
38
Table 3.5: Difference in average palatal vault height and
intermolar widths at time points T1, T2, T3.
T2-T1
Variable
Mean ± SD
PVH6
1.50 ± 2.18
PVHM
T3-T2
± SD
Sig.
Mean ± SD
Sig.
0.00**
0.67 ± 2.14
0.11
2.17 ± 2.32
0.00**
0.83 ± 1.80
0.02*
0.10 ± 1.86
0.79
0.93 ± 1.90
0.01*
RCLC
6.06 ± 3.71
0.00**
-0.16 ± 2.37
0.72
5.90 ± 3.71
0.00**
GLLine
5.97 ± 3.17
0.00**
0.23 ± 2.09
0.56
6.20 ± 3.01
0.01*
Units: millimeters
Sig.
*: 0.05>p value> 0.01
Mean
T3-T1
**: p value < 0.01
The average palatal vault height between the first
maxillary molars significantly deepened as the patient grew
from average age 12 years to average age 16 years. In
retention, the palatal vault height continued to nonsignificantly grow over the next 11 years. The average
palatal vault height halfway from the maxillary first
molars to the incisive papilla grew significantly from T1T2 but non-significantly from T2-T3. The net gain T1-T3 for
both palatal vault height measurements were significant.
The intermolar width significantly expanded from T1T2. The 0.09 mm difference may be due to dental tipping or
measurement error. No significant relapse was noted in
retention between the centroid (RCLC) and the gingival
lingual margin (GLLine) in T2-T3. From T1-T3 there were
significant net gains in intermolar width.
39
Discussion
This study has demonstrated that there is no
relationship between the palatal vault height and the rapid
palatal expansion stability. Therefore, no clear answer
regarding the amount of expansion necessary to correct the
crossbite and maintain it has be achieved through the
initial palatal vault height to improve efficiency of
treatment involving expansion.
The intermolar width from the gingival lingual margin
at the average age 12 years 3 months, was 28.99 mm. This
was significantly reduced compared to Yang’s et al. study
showing their 12 years old patient to have an average 36.19
mm intermolar width at the gingival lingual margin.16 The
post-treatment expansion at average age 16 years 0 months
was 34.96 mm which is still less than the recorded 36.55 mm
at age 14 in the 9 year longitudinal study.16
The lingual gingival margin width at 5.97 mm ± 3.17 mm
was slightly less than the 6.06 mm ± 3.71 mm measured from
centroid width, RCLC. This could be attributed to either
dental tipping or measurement error. In retention, the RCLC
width experiences relapse while there is continued increase
in the transverse dimension according to the GLLine width.
This could possibly be attributed to settling of the
40
occlusion.2 The transverse width continues to grow providing
more translational increases.5
This study contradicts Lima et al. showing a 5.95 mm
increase and during retention a 0.46 mm decrease when
measured from the lingual gingival margin.4 In agreement
with this study, McNamara shows that the centroid
intermolar width decreased 0.02 mm in retention.2 Both
studies utilized Haas type RPE. Initial studies showed that
the Haas expander offered more stability from its toothtissue borne design.9 In contrast, later studies show
similar results in Haas expanders and other expander
designs.10 According to Weisseimer et al. more tipping
occurs with the Haas type expander when compared to the
Hyrax type expander.5
The palatal vault height continued to change and grow
through treatment and into retention. Greater change was
noted in the palate at the level of the first maxillary
molars when compared to the midpoint from the molars to the
incisive papilla, roughly at the first bicuspids. For the
intermolar height, the initial height was 12.90 mm ± 2.35
mm at the average age 12 years 3 months. This corresponds
with Yang et al. where the height at the same location for
12 year olds was 12.97 mm.16
In this study, the height at
roughly the first biscupids was 10.94 mm ± 1.84 mm, which
41
was deeper than the reported 9.39 mm reported in Yang’s et
al. nine year longitudinal growth study.16
The significant increase of the palatal vault may
either be attributed to the orthodontic treatment or the
natural dental eruption of the alveolar processes.11
According to Iwasaki et al. increasing the transverse
dimension, allows for high tongue posture against the
palate.13 Following expansion, the raising of the tongue
provides greater lingual force to be exerted against the
dentition to maintain an equilibrium with the muscles of
the cheek.12 This study shows significant increases of PVH6
and PVHM.
There are many ways to measure palatal vault height,
which makes comparison difficult. According to Heiser et
al. a more precise method of using a gingival plane as a
reference involves a least square algorithm connecting the
margins of all posterior teeth.17 In contrast, the occlusal
plane can be used as a reference. In the study by Spillane,
the palatal vault height decreased from 17.6 mm to 17.0 mm
after expansion. However at one and two years retention
there was an increase to 17.7 mm and 18.3 mm,
respectively.11 According to Almeida et al. the rugae may be
used as landmarks for measuring the palatal vault height.
The rugae are reported to being stable and reproducible
42
landmarks when looking at the first three anterior rugae.
The medial point of each rugae has been shown to be more
reproducible at different time points than the lateral
ruage point.18
Gohl et al. notes that lateral cephlametrics can be
used to measure the highest point in the palatal vault.
This removes the soft tissue thickness from the height,
instead focusing on a line drawn parallel to the Frankfort
plane that goes through the CEJ.19 This removal of soft
tissue could lessen some variation in the patients.
Previous anthrological studies measured cadaver skulls
without tissue, removing the variability of the soft
tissue. This method is not viable for living patients,
instead the lateral cephlametric measurements by Gohl et
al. can be used to remove the soft tissue variation.20,
21
Conclusions
The evidence collected in this study showed that there
is no relationship between the initial palatal vault height
and rapid palatal expansion with the Haas type expander.
The Haas type expander and edgewise non-extraction
therapy demonstrated significant maxillary first molar
width increases during orthodontic treatment (T1-T2) and
into retention (T1-T3). Whereas no significant intermolar
43
width relapse was noted following orthodontic treatment
into retention, T2-T3.
The palatal vault showed significant increase from T1
to T2 and significant total net increase from T1 to T2 for
both palatal vault landmarks, PVH6 and PVHM. There was nonsignificant increases following expansion into retention at
T2-T3.
44
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1. Angell E. Treatment of irregularities of the permanent
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Rapid maxillary expansion followed by fixed
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dimensions. Angle Orthod 2003;344-53.
3. Haas AJ. Palatal expansion: just the beginning of
dentofacial orthopedics. Am J Orthod 1970;219-55.
4. Lima Filho RM, de Oliveira Ruellas AC. Long-term
maxillary changes in patients with skeletal Class II
malocclusion treated with slow and rapid palatal
expansion. Am J Orthod Dentofacial Orthop 2008;383-8.
5. Weissheimer A, de Menezes LM, Mezomo M, Dias DM, de Lima
EM, Rizzatto SM. Immediate effects of rapid maxillary
expansion with Haas-type and hyrax-type expanders: a
randomized clinical trial. Am J Orthod Dentofacial
Orthop 2011;366-76.
6. Garib DG, Henriques JF, Janson G, Freitas MR, Coelho RA.
Rapid maxillary expansion--tooth tissue-borne versus
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7. McNamara JA. Maxillary transverse deficiency. Am J
Orthod Dentofacial Orthop 2000;567-70.
8. Kutin G, Hawes RR. Posterior cross-bites in the
deciduous and mixed dentitions. Am J Orthod 1969;491504.
9. Haas AJ. Long-term posttreatment evaluation of rapid
palatal expansion. Angle Orthod 1980;189-217.
10. Huynh T, Kennedy DB, Joondeph DR, Bollen AM. Treatment
response and stability of slow maxillary expansion
using Haas, hyrax, and quad-helix appliances: a
retrospective study. Am J Orthod Dentofacial Orthop
2009;331-9.
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11. Spillane LM, McNamara JA, Jr. Maxillary adaptation to
expansion in the mixed dentition. Semin Orthod
1995;176-87.
12. Küçükkeleş N, Ceylanoğlu C. Changes in Lip, Cheek, and
Tongue Pressures After Rapid Maxillary Expansion Using
a Diaphragm Pressure Transducer. The Angle
Orthodontist 2003;662-8.
13. Iwasaki T, Saitoh I, Takemoto Y, Inada E, Kakuno E,
Kanomi R, Hayasaki H, Yamasaki Y. Tongue posture
improvement and pharyngeal airway enlargement as
secondary effects of rapid maxillary expansion: A
cone-beam computed tomography study. American Journal
of Orthodontics and Dentofacial Orthopedics 2013;23545.
14. Ohkiba T, Hanada K. Adaptive functional changes in the
swallowing pattern of the tongue following expansion
of the maxillary dental arch in subjects with and
without cleft palate. Cleft Palate J 1989;21-30.
15. Doyle R. Long-term stability in the maxillary and
mandibular arch dimensions using rapid palatal
expansion and edgewise mechanotheraphy in growing
patients. Unpublished. 2012.
16. Yang ST, Kim HK, Lim YS, Chang MS, Lee SP, Park YS. A
three dimensional observation of palatal vault growth
in children using mixed effect analysis: a 9 year
longitudinal study. Eur J Orthod 2013;832-40.
17. Heiser W, Niederwanger A, Bancher B, Bittermann G,
Neunteufel N, Kulmer S. Three-dimensional dental arch
and palatal form changes after extraction and
nonextraction treatment. Part 2. Palatal volume and
height. Am J Orthod Dentofacial Orthop 2004;82-90.
18. Almeida MA, Phillips C, Kula K, Tulloch C. Stability of
the palatal rugae as landmarks for analysis of dental
casts. Angle Orthod 1995;43-8.
19. Gohl E, Nguyen M, Enciso R. Three-dimensional computed
tomography comparison of the maxillary palatal vault
between patients with rapid palatal expansion and
orthodontically treated controls. Am J Orthod
Dentofacial Orthop 2010;477-85.
46
20. Redman RS, Shapiro BL, Gorlin RJ. Measurement of normal
and reportedly malformed palatal vaults. II. Normal
juvenile measurements. J Dent Res 1966;266-9.
21. Vidic B. Variations in height of the palatum osseum as
a function of other vertical dimensions and angles of
the skull. J Dent Res 1971;14-6.
47
Vita Auctoris
Christopher Michael Ruth was born on April 14, 1986 in
Fenton, Michigan to Gary and Cheryl Ruth. He is the oldest
of four children: Nicholas, Lauren and Patrick. He grew up
in Richmond, VA and Louisville, KY before graduating from
Charlotte Catholic High School in Charlotte, NC. He
attended University of North Carolina Charlotte in 2008
with a Bachelors of Art in Chemistry and a minor in
Biology. Later, he graduated from Virginia Commonwealth
University with a Doctorate in Dental Surgery in 2012.
Following dental school, he attended Saint Louis
University’s orthodontic residency and plans to complete
his Masters of Science in Dentistry in December 2014. He
plans to pursue a career as an associate orthodontist.
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