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Three dimensional analysis of maxillary retromolar alveolar bone before and after en‐masse distalization

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Three dimensional analysis of maxillary retromolar alveolar bone before and after en‐masse distalization

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THREE DIMENSIONAL ANALYSIS OF MAXILLARY RETROMOLAR ALVEOLAR BONE
BEFORE AND AFTER EN-MASSE DISTALIZATION

BY

Tina Keun Nan Park

A Thesis Presented to the
FACULTY OF THE USC GRADUATE
SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the Requirements for the Degree
MASTER OF SCIENCE
(CRANIOFACIAL BIOLOGY)

MAY 2016

Copyright 2016 Tina K. Park
1

Table of Contents
Abstract 2
Chapter 1: Background 5
1A. Preface 5
1B. Indications for En-masse Maxillary Arch Distalization 5
1C. Review of Distalization Appliances 8
1D. Skeletal Anchorage System 14

Chapter 2: Anatomy and Biology 20
2A. Anatomic Boundaries of the Maxillary Retromolar Alveolar Bone 20
2B. Biology of Alveolar Bone Remodeling 21

Chapter 3: Technique in Craniofacial Structure Measurements 23
3A. Panoramic & Cephalometric VS CBCT 23
3B. 3D Cephalometric Digitization and Measurements 24

Chapter 4: Our Current Study Objectives 26
Chapter 5: Materials and Methods 27
Chapter 6: Results 31
Chapter 7: Discussion 34
Chapter 8: Conclusion 42
List of Figures and Tables 43
References 53

2

Abstract
Purpose: The objectives of this study were: 1.To study the changes in the
maxillary retromolar alveolar bone dimensions in response to Modified Palatal
Anchorage Plate (MPAP) assisted maxillary en-masse dental distalization, and 2.
To evaluate the bone level at the distal surface of the distalized second molar.
Methods: In this retrospective study, the pre- and post-treatment CBCTs of 41
Class II subjects treated with the MPAP appliance were analyzed using Invivo 3D
cephalometric analysis software (version 5.3; Anatomage, San Jose, Calif). Four
landmarks for reference, five landmarks bordering the three dimensional limits of
the maxillary retromolar bone, and the CEJ at the distal surface of the second
molar were digitized for each subject pre- and post-treatment. The following
linear measurements were calculated: length, height and width of the retromolar
alveolar bone, and the bone level at the distal surface of the second molar. The
pre-treatment retromolar alveolar bone dimensions were compared with that of
54 normal occlusion subjects to rule out abnormal maxillary growth in class II
subjects. A paired t-test was used to analyze the changes in retromolar alveolar
bone dimensions before and after treatment with significance at α=0.05.
Results: The mean (±SD) pretreatment maxillary retromolar alveolar bone
measurements (width, height, and length) for the class II malocclusion group were
3

as follows: 13.36 ± 2.06 mm, 7.86 ± 1.99 mm, 7.29 ± 3.14 mm. The values were
not significantly different from that of the normal occlusion group (12.98 ± 2.02
mm, 7.92 ± 1.96 mm, 7.88 ± 2.01 mm). After undergoing treatment, the
retromolar alveolar bone width, height and length significantly decreased
(p<0.001) to 12.08 ± 2.58 mm, 6.36 ± 2.21 mm and 5.14 ± 2.71 mm, respectively.
Statistical comparison between the actual post-treatment length 5.14 mm and
the expected post-treatment value of 4.57 mm (pre-treatment length 7.29 mm
minus amount of molar distalization 2.72 mm) showed significant increase in the
total bone length during treatment by 0.57mm. Bone coverage at the distal
surface of the maxillary second molar (2.04 ± 1.33 mm for pre and 2.03 ±1.28 mm
post treatment) did not show significant change.
Conclusion: As maxillary teeth are distalized, they move into bone that is smaller
in the dimensions of length, width and height. In all 41 treated cases, there was
sufficient bone length remaining post-distalization. Together with the observed
bone deposition at the leading end, it can be concluded that there is sufficient
retromolar bone length to accommodate maxillary dental distalization. This study
also showed that maxillary en-masse distalization with the MPAP appliance does
not lead to periodontal defects at the distal surface of the second molar.
However, further studies must be done to evaluate if there is active bone
4

remodeling in all three dimensions to maintain the bony housing around the
distalized second molar. It would be beneficial for clinicians to use the method
described in this study to assess the available retromolar alveolar bone when
planning maxillary en-masse distalization.

5

Chapter 1. Background

1A. Preface
According to Proffit, there are four major approaches to Class II problems in
non-growing adult patients. The four approaches are as follows: 1. retraction of
the maxillary incisors into premolar extraction space, 2. combination of retraction
of the upper teeth and forward movement of the lower teeth using class II
interarch mechanics, 3. distal movement of the maxillary molars, and eventually
the entire upper arch, and, 4. orthognathic surgery (Proffit et al., 2007). The
applicability and safety of the third option, en-masse distalization of the maxillary
dentition, is the focus of this study. In the following sections, indications and
contemporary techniques for en-masse distalization of the maxillary arch will be
reviewed in detail.
1B. Indications for En-masse Maxillary Dental Distalization
Extraction of bicuspids has been routinely prescribed in orthodontics, either
to correct excessive overjet or to correct the molar relationship in Class II
malocclusion patients (Proffit et al., 2007). However, extraction of pristine teeth
for orthodontic cause is not readily accepted by the patients and occasionally
derided by the restorative dentists (Tekale et al., 2015). Moreover, exodontia
caries moderate health risks, especially for patients with bleeding disorders and
6

patients under bisphosphonate therapy (Anderson et al., 2013, American Dental
Association Council on Scientific, 2006). Non Extraction approach with
proclination of the mandibular teeth to achieve class II correction is limited by the
mandibular alveolar housing and results in questionable post treatment stability
(Tweed, 1944, Yared et al., 2006). In these scenarios, en-masse distalization of
the maxillary arch becomes an indispensable non-extraction treatment option for
class II malocclussion patients.
En-masse distalization of the maxillary arch is sometimes necessary in class
II extraction cases. Anchorage management is one of the keys to successful
treatment of bicuspid extraction cases, especially for severe class II cases.
Multiple anchorage holding appliances and techniques have been described in
literature, however unless skeletal anchorage is used, some extent of unintended
anchorage loss occurs when closing extraction space (Feldmann and Bondemark,
2006). Severe anchorage loss could result when one or more of these problems
occur: poor treatment planning, error in execution of the mechanics, and/or poor
patient cooperation. When overjet remains with the extraction spaces
completely closed, and mandibular incisors already proclined to its limit, regaining
anchorage in middle of treatment could only be achieved through en-masse
7

distalization of the maxillary arch or extraction of more teeth (Tanaka et al.,
2008) .
For skeletal class II adults with crowding and/or dentoalveolar protrusion,
both bicuspid extractions and orthognathic surgery may be required. If there are
no vertical or transverse components, mandibular advancement surgery alone
can suffice. According to Bailey et al., mandibular advancement less than 10 mm
is highly stable with more than 90% chance of less than 2 mm change and almost
no chance of more than 4 mm of change during the 1 post-surgical year (Bailey et
al., 2004). However, a long term follow up study by Eggensperger et al. reported
up to 50% relapse of the mandibular advancement 12 years post-surgery, even
with rigid fixation (Eggensperger et al., 2006). The most ideal treatment option at
this point would be to re-operate to regain Angle Class I occlusion with face
harmony. However, considering the cost and the complications involved with
orthognathic surgery, patients may seek alternative non-surgical treatment
options (Khechoyan, 2013). Use of class II elastics or similar non-compliance
appliances to guide both the maxillary and mandibular teeth together back to
class I occlusion may be appropriate in some cases. In cases where protraction of
the mandibular dentition is not warranted, en-masse distalization of the maxillary
dentition to regain functional class I occlusion should be considered as an option.
8

Careful case selection is necessary, as retraction of the maxillary dentition is often
not recommended as it reduces the upper lip support and may increase nasolabial
angle (Talass et al., 1987).
The indications for en-masse distalization of the maxillary dentition are not
limited to the scenarios mentioned above and can further be extended to a
multitude of situations in orthodontics.
1C. Review of Distalization Appliances

Extraoral Compliance Dependent
Headgear has been widely used for growth modification ever since
cephalometric studies in 1950’s demonstrated that it could limit the growth of the
maxilla (Figure 1A). However, it was originally utilized for the purpose of
distalization of maxillary posterior dentition (Proffit et al., 2007). Headgear can
provide multiple advantages due to its adjustability. In conjunction with maxillary
dental distalization, it can be used to assist in correction of transverse
discrepancies and also used to intrude or extrude molars to the provider’s
advantage (Nanda et al., 2005). There is no question about the effectiveness of
headgear in providing both orthopedic and dental changes, but it is completely
dependent on patient compliance. According to a study by Brandao et al, patients
9

only wore their headgears 56.7% of the time which is well below the time
required to produce effective orthopedic modification or dental movements
(Brandao et al., 2006). One of the main reasons for difficulty in achieving good
compliance with headgear is high visibility of the appliance and the possible
negative psycho-social impact on the patient (Agar et al., 2005, Sergl et al., 2000).
Intraoral Compliance Dependent
To increase patient compliance by reducing appliance visibility, intraoral
distalization devices such as the Wilson Bimetric Arch became available. The
active component of the Wilson Bimetric Arch is the open coil spring that is
placed between an omega loop and the first maxillary molar. This coil spring
provides a force to distalize the maxillary molars when activated by a class II inter-
maxillary elastics worn to the hook on the arch mesial to the cuspid (Wilson,
1955)(Figure 1B). The premolar and canines usually drift distally allowing molar
and canine correction into class I relationship in as little as 6-12 weeks (Nanda et
al., 2005). Ucem et al. demonstrated an average of 3.5 mm of distal molar
movement with 1.8 degrees of distal tipping using the Wilson Bimetric Arch in 14
class II adolescent patients. However, use of inter-arch mechanics may result in
mandibular incisor flaring even when mandibular anchorage is held with a lingual
10

arch or lip bumper (Ucem et al., 2000). Muse et al. reported that with the
Bimetric arch, 50.7 percent of Class II correction was obtained by upper molar
distalization (2.16mm) and 39.8 percent by lower molar mesialization (1.38 mm).
Other side effects include maxillary incisor protrusion, proclination and extrusion
from poor patient cooperation with elastic wear (Muse et al., 1993).
Intraoral Non-Compliance
The pendulum, Jones Jig and the distal jet appliances are intraoral non-
compliance maxillary molar distalization appliances developed for class II
correction.
The pendulum appliance was described by Hilgers in 1992. It consists of
0.032 inch Titanium Molybdenum Alloy (TMA) distalization springs extending
from a palatal acrylic plate bonded to the premolars to the lingual sheaths on the
molar tube, distalizing the molars with a force of 230g per side (Hilgers, 1992)
(Figure 1C). According to Hilgers, as much as 5 mm of molar distalization can be
achieved within 3 to 4 months. The pendulum appliance eliminated the need of
patient compliance and use of interarch mechanics. Many studies evaluating the
technique support its effectiveness in distalizing not only the first molars but even
the second molars (Ghosh and Nanda, 1996). However, the molars are distalized
11

at the expense of the loss of anchorage of premolars and maxillary incisors. It
was shown that with the pendulum appliance, 4.7 mm of distal molar movement
was achieved with 9.0 ˚of molar distal tipping, 2.7 mm of premolar anchorage loss
and 5.0˚ of incisor proclination (Caprioglio et al., 2015). Nanda and Ghosh
reported that maxillary space was created by 57% of molar distalization and 43%
of anchorage loss. Also when used after eruption of maxillary second molar,
extrusion of first molars could result, with consequent increase in lower anterior
facial height and in Frankfort mandibular plane angle (Bussick and McNamara,
2000). With careful case selection and anchorage management, the pendulum
appliance can be used to effectively correct class II malocclusion.
In the same year, another non-compliance maxillary molar distalization
appliance was introduced, the Jones Jig, named after its inventor (Jones and
White, 1992). Similar to the pendulum appliance, the Nance palatal button
attached to the first or the second premolars is used as the anchorage unit. The
jig, which is activated by a nickel titanium coil spring between the molar and the
second premolar, is assembled from the buccal surface, making adjustments
easier (Nanda et al., 2005) (Figure 1D). With 70 to 75 g of continuous force
exerted onto the molar without the need of patient’s compliance, molar
correction, taking 10.7 months with extraoral traction, can be achieved in 2.5
12

months (Haydar and Uner, 2000). However, as in the pendulum appliance, there
is a significant reciprocal movement consisting of, tipping and extrusion of
premolars in the mesial direction. To achieve 2.51 mm of maxillary molar
distalization, there is 7.53 ˚ of molar distal tipping and 2.0 mm of mesial
movement and 4.75 ˚ mesial tipping of the premolar (Brickman et al., 2000).
According to Patel et al. monthly rate of distal movement with the Jones Jig is
similar to that of the Pendulum but there is significantly more loss in anchorage
indicated by more mesial tipping and extrusion of the second premolars (Patel et
al., 2009).
In 1996 Carano and Testa introduced the distal jet (Carano and Testa,
1996). Design of the appliance resembles that of the Nance and the pendulum
appliances but with slight modifications to place the force of distalization closer to
the center of resistance of the first molar. This is achieved by constructing the
tube/piston and coil spring assembly superiorly to the crown of the first molar.
This tube/piston and coil spring is embedded in a modified acrylic Nance palatal
button that is anchored to the first premolars. And it is connected to the lingual
sheath of the first molar by a bayonet wire (Nanda et al., 2005) (Figure 1E). This
unique design of the distal jet appliance provides several advantages compared to
the pendulum and the Jones Jig, including less distal tipping and more bodily
13

distalization of the first molar. However, although less than other previously
mentioned distalizing appliances, there was a significant loss of anchorage of the
anterior segment (Ngantung et al., 2001). Bolla et al. reported that with the distal
jet, 3.2 mm maxillary first molar was distalized with 3.1 ˚distal tipping, 1.3 mm of
first premolar mesial movement and 3.1˚ mesial crown tipping. Thus, space is
created with 71 % molar distalization and 29 % reciprocal anchorage loss. The
rate of distalization was shown to be slightly slower than that of the pendulum
and the Jones jig appliances, distalizing at a rate of 0.6 mm per month. Bussick
and McNamara showed that with the pendulum appliance, a mild increase in the
mandibular plane angle was seen during distalizing when second molars were
erupted (Bussick and McNamara, 2000). Interestingly, with the distal jet,
distalizing after eruption of the maxillary second molar resulted in significantly
less distal tipping and extrusion of the first molars compared to when used before
eruption, producing less vertical change (Bolla et al., 2002).
Although effective, both intraoral non-compliance and extraoral maxillary
molar distalization appliances have disadvantages that offset the benefits. The
intraoral non-compliance maxillary molar distalization appliances significantly
increased the rate of molar distalization, but at the cost of anterior anchorage
loss. Patient compliance with headgear or class II elastics is required at some
14

point to hold or reinforce posterior anchorage while retracting the anterior teeth
into the space created. Moreover, tipping and extrusion of the molars and the
premolars cannot be predictably controlled.
1D. Skeletal Anchorage System
The concept of skeletal anchorage in orthodontics arose with the success of
osseointegration of implants in bone. With skeletal anchorage, Newton’s third
law no longer became a problem in orthodontics. Anchorage plates and mini-
implants specifically designed for orthodontics became available and widely used
in the early 21
st
century. In this subsection, the use of skeletal anchorage system
in optimization of maxillary molar distalization will be discussed.
Temporary Skeletal Anchorage Devices (TSADs) or Titanium Mini Screws
TADs became more widely used in orthodontics in the 21
st
century. These
titanium mini screws ranging in size from 1.2-2.5mm in diameter and 6.0-11 mm
in length can easily be placed with minimal patient discomfort (Cope, 2005,
Reynders et al., 2009). For maxillary molar or en-masse distalization, use of
TSADs placed in the buccal interradicular space or the palatal bone have been
reported in literature. For the buccal approach, a miniscrew is usually inserted
between the maxillary first molar and the second premolar on each side being
15

distalized. Either an elastic power chain or nickel titanium closed coil spring is
attached from the mini screw to a class II hook or to an anterior tooth depending
on the desired force vector (Figure 2A). This system was described in case reports
by Tekale et al. and Oh et al. where patients with Class II malocclusion were
treated to Class I via maxillary en-masse distalization (Tekale et al., 2015, Oh et
al., 2011). Oh et al. was able to produce 1.4 to 2.0 mm of posterior teeth
distalization with 3.5˚ of distal tipping and 1 mm of posterior teeth intrusion.
TSADs can be used in combination with other intra-oral distalizing devices
as an anchorage reinforcement. Choi et al., used a modified pendulum appliance
with one midpalatal miniscrew as an anchorage to distalize the second molars.
Two buccal TSADs were added later in treatment to distalize the rest of the
anterior segments (Choi et al., 2011).
The success rate of TSADs ranges from 79% to 96% according a meta-
analysis published by Dalessandri et al. (Dalessandri et al., 2014). This wide range
of success rates indicates technique sensitivity of TSAD placement. Many factors
are involved in the success of TSADs, including diameter and length of implant
used, proximity to adjacent roots, direction of loading, and loading force (Sendax,
2013). The recommended maximum loading force for TSADs is 250-300 g which
16

may be sufficient for maxillary molar distalization, but questionable for en-masse
distalization.
Zygomatic Implanted Anchorage Plate
A titanium plate anchored on the zygomatic buttress with two or three
implants has been reported to produce a stable and sufficient force system for
maxillary en-masse distalization (Sugawara et al., 2006, Tanaka et al., 2008).
Sugawara et al. used a plate anchored by three implants 2 mm in diameter and 5
mm to distalize the entire maxillary dentition with 500 g of force per side with
nickel titanium open coil springs (Figure 2B). With this system the average
amount of distalization of the maxillary first molars was 3.78 mm at the crown
level and 3.20 mm at the root level. The maximum displacement was 6.8 mm at
the crowns and 6.0 mm at the roots. Tanaka et al., used the same system to treat
a patient with 7.6 mm of overjet and missing maxillary first premolars from
previous orthodontic treatment. The entire treatment time was 2 years and the
final molar occlusion was in angle class I and overjet reduced to 1 mm.
The disadvantage of this method is the surgical operation required for
placement of the plate. The procedure is usually performed under intravenous
sedation, since a full mucoperiosteal flap has to be elevated beyond the
17

zygomatic buttress to expose the cortical bone. Patients experience mild to
moderate pain and swelling several days after surgery (Sugawara et al., 2006).

Modified Palatal Anchorage Plate (MPAP)
The palate has become a popular site for skeletal anchorage placement
since there is no vital structure in the area of interest, eliminating the need of
reimplanting mini-screws as in the buccal TSADs approach (Sa'aed et al., 2015).
The palatal bone has sufficient bone density and thickness to support multiple
mini-implants. Moreover, it is covered with keratinized gingiva, thus is less
susceptible to inflammation (Kang et al., 2007a). Unlike the zygomatic buttress
which has to be accessed through a full mucoperiosteal flap under intervenous
sedation, the palate is easily accessible and multiple mini-screws can be used to
support a similar plate type device with just local anesthesia. Patients experience
only minor discomfort and force can be loaded immediately after placement of a
palatal plate (Kook et al., 2014a). Taking advantage of these characteristics of the
palate, Kook et al. developed the Modified Palatal Anchorage Plate (MPAP) which
can be used to efficiently to distalize maxillary molars and provide en-messe
maxillary retraction (Kook et al., 2010).
18

The MPAP design allows the skeletal anchorage unit to be inserted more
anteriorly in the paramedian palatal region, which has been shown to provide
better stability due to higher bone density in both adults and adolescents (Han et
al., 2012, Kang et al., 2007b). Bilateral arms are extended distally which allows
longer range of action when connected to the hooks on the mesially extended
trans-palatal arch via a nickel titanium closed coil spring (Figure 2C). The line is
action is at the level of the palate which is near, or more apical to, the center of
resistance of the maxillary molars, producing more bodily distalization and
preventing extrusion. A finite element study comparing the tooth displacement
between buccal mini-implants and palatal plate anchorage for molar distalization
showed that placing mini-implants on the buccal side caused the first molars to be
distally tipped and extruded, while the incisors labially flared and intruded.
Distalization with the MPAP showed bodily movement of the molars and
insignificant effect on the incisors (Yu et al., 2011). The results were confirmed by
another study on treatment effects of the MPAP using 20 consecutively treated
Class II patients. The study showed that with the MPAP, the maxillary first molar
was distalized 3.3 mm at the crown and 2.2 mm at the root level, with distal
tipping of 3.4 ˚. Kook et al., showed that MPAP even produces slight intrusion of
19

the molars (1.8 mm) during distal movement which can help maintain anterior
facial height (Kook et al., 2014b).
The MPAP can be safely used in class II adolescents to produce skeletal and
dental effects. A study showed that the MPAP can produce the comparable effect
on the maxilla as a cervical headgear in distalizing maxillary molars and correcting
the sagittal skeletal maxillomandibular differences (Sa'aed et al., 2015). The
design of the MPAP not only allows the skeletal anchorage units to be placed
more anteriorly but it also avoids the midsagittal suture. In adolescents, the
palatal bone might be significantly thin in the midsagittal area due to incomplete
ossification of the mid-palatal suture (Han et al., 2012). Also placing the mini-
implant in the suture can interfere with the growth of the suture.
With either extra-oral, non-compliance intraoral appliances, TSADs, or with
the MPAP, current studies show that en-masse distalization of maxillary dentition
is mechanically possible (Table 1).

20

Chapter 2. Anatomy and Biology

2A. Anatomic Boundaries of the Maxillary Retromolar Bone
The amount that maxillary teeth can be distalized is limited by the
boundaries set by human anatomy. Orthodontic tooth movements encroaching
the anatomic boundaries can lead to osseous dehiscence and soft tissue
fenestration. For example, over expanding the dental arch antero-posteriorly or
transversely has shown to cause detrimental effect on the periodontal health,
especially in adults (Shiloah et al., 1987, Baysal et al., 2013). Understanding the
biological and anatomical limitations is crucial in applying the available technology
more effectively and safely.
The maxillary tuberosity is posteriorly bordered by the pterygoid plate of
the sphenoid bone (Netter, 2010)(Figure 3). The maximum amount of maxillary
molar distalization reported was 6.8 mm using the zygomatic implanted
anchorage plate (Sugawara et al., 2006). Although one of the case selection
criteria for the study carried by Sugawara et al. was that there was sufficient
space behind the first molar for second and third molars after distalization, the
method of measuring this space was not described. The maxillary distalization
studies mentioned in previous sections reported the amount of maxillary molars
21

distalized, but none reported the amount of space available prior to distalization.
The space available for distalization and the periodontal health of the distal
surface of the second molar post-distalization need to be measured to assess the
safety of this treatment modality.
2B. Biology of Alveolar Bone Remodeling
If bone could be deposited in the distal region of the retromolar bone
through the process of bone remodeling to accommodate the distalized maxillary
second molar, the anatomical limits of the distalization mechanic could be
extended.
The osteogenic potential of orthodontic tooth movement has been
recognized and utilized in many different disciplines of dentistry. For example,
limited alveolar bone regeneration via orthodontic tooth movement can be used
for implant site development and improving vertical bone height (Zachrisson,
2005). In orthodontics, this phenomenon is embraced by the Damon System,
which claims that through use of light-force buccal alveolar bone can be
remodeled to accommodate the arch development or expansion (Graber et al.,
2005). Many studies have been performed to evaluate this claim, including a
randomized clinical trial study done by Cattaneo et al. which concluded that the
22

buccal bone remodeling with the Damon system could not be verified with the
CBCT scans at this point (Cattaneo et al., 2011). However, there have been
multiple studies supporting the views of the Damon system, showing osteoblastic
periodontal remodeling during treatment or even in retention period. A study by
Kraus et al. demonstrated that light-moderate continuous expansion force is
followed by bone formation on the periosteal surfaces of cortical bone (11). Even
with rapid maxillary expansion, recovery of buccal plate thickness was seen 6
months after retention (Ballanti et al., 2009). Three dimensional evaluation of
periodontal remodeling revealed that bony dehiscence which resulted from
mandibular anterior protrusion during treatment and persisted through two year
post treatment, was shown to be filled with newly remodeled bone three years
post treatment (Fuhrmann, 2002). Bone remodeling capacity of the maxillary
retromolar region has not been previously studied in context of molar
distalization and thus should be evaluated to fully evaluate the efficacy of en-
masse maxillary distalization.

23

Chapter 3. Technique in Craniofacial Structure Measurements
3A. Panoramic & Lateral Cephalometric VS Cone Beam Computed Tomography
Because of vertical and horizontal magnification, distortion, and
superimposed anatomic structures, two dimensional images such as panorex or
lateral cephalograms can provide only limited information of three dimensional
dentomaxillofacial structures (Reddy et al., 1994, Tronje et al., 1982). Cone beam
computed tomography (CBCT) is an imaging modality introduced in the medical
field in the 1990’s that overcomes the above limitations. It can produce a high
contrast and detailed volumetric three dimensional reconstruction of a
craniofacial structure. This technology has multiple clinical applications in
orthodontics. 1. CBCT provides more accurate location and morphology of
impacted teeth or other oral abnormalities. This diagnostic power is especially
useful for patients with cleidocranial dysplasia, a genetic disorder characterized
by multiple supernumerary and impacted teeth (Dalessandri et al., 2011). 2.
Three dimensional airway volume analysis and temporomandibular joint
morphology assessment can be performed with high precision (Kau et al., 2005).
3. With a CBCT scan, multiple slices of a craniofacial structure in any plane of
space can be constructed. This allows accurate assessment of periodontal bone
24

loss, and can even detect bone craters and furcation involvement with high
precision (Vandenberghe et al., 2008) .
3B. 3D Cephalometric Digitization and Measurements
Recent studies show that CBCT can provide accurate and reliable
craniometrics measurements in three dimensions. Kamburoglu et al. showed that
accuracy of the craniometrics measurements made on CBCT scans is comparable
to that of direct measurements made on dry skulls with digital caliper
(Kamburoglu et al., 2011). Some of the mandibular, maxillary and skull base
distances measured by Kamburoglu et al. include distance between left and right
angulus mandibulae and distance between left and right fovea pterygoidea. With
3D cephalometric analysis software such as InVivo software (version 5.3;
Anatomage, San Jose, Calif) or SimPlant Ortho 2.0 (Materialise Dental, Lueven,
Belgium), different structures or points on the skull can be precisely digitized and
linear measurements between different points or planes can be calculated by the
software. Gribel et al., showed that craniometrics measurements using this
method is accurate to subvoxel size and is comparable to direct measurements
made on a dry skull (Gribel et al., 2011).
25

In the following chapters, a study utilizing the latest 3D cephalometric
digitization technique to measure the maxillary retromolar bone length, height
and width will be described.

26

Chapter 4. Our Current Study Objectives
The objective of this study is two-fold. 1. To quantify the changes in the
maxillary retromolar alveolar bone dimensions in response to en-masse dental
distalization. 2. To analyze changes in bone coverage at the distal surface of the
second molar to evaluate the safety of maxillary en-masse distalization. These
objectives are evaluated by comparing the three dimensional retromolar bone
cephalometric measurements made on CBCT images before and after distalization
with the MPAP appliance.

27

Chapter 5. Materials and Methods

The sample of this retrospective study consisted of CBCT scans of 21 class II
malocclusion (6 male, 15 females) and 27 normal occlusion patients (12 male, 15
females). The two sides of the maxillae were treated independently, doubling the
sample size to 41 for treated (one side of one of the patients did not meet the
criteria) and 54 for normal occlusion samples. The scans were obtained from the
Department of Orthodontics, Seoul St. Mary’s Hospital, Catholic University of
Korea patient database.
The inclusion criteria for the class II malocclusion cases were as follows: (1)
non-syndromic; (2) young adults (age ranging from 16-35); (3) available pre- (T1)
and post- (T2) treatment CBCT scans (4) exclusive use of the MPAP appliance for
distalization. The normal occlusion cases were selected according to the
following criteria: (1) Angle class I occlusion; (2) crowding ≤ 2 mm or spacing ≤ 1
mm; (3) normal shape and size teeth. The class II samples were compared to the
normal occlusion sample to rule out abnormal maxillary growth in class II
samples. Approval was obtained from the Health Sciences Institutional Review
Board of the University of Southern California (HS-14-00852), and informed
consent was provided according to the Declaration of Helsinki.
28

The CBCT images (before and after distalization) were taken with an iCAT
scanner (Imaging Science International,Hatfield, Pa). The scanning parameters
were 120 kV, 47.7 mAs, 20 seconds per revolution,170 3 130 mm field of view,
and voxel size of 0.4 mm. Each seated subject's head position was oriented so
that the Frankfort plane was parallel to the floor, and the images were taken at
the intercuspal position.
The CBCT data were exported in DICOM multi-file format and imported into
Invivo software (version 5.3; Anatomage, San Jose, Calif) for 3-dimensional
volume rendering. Reorientation of the head position of each scan was performed
as follows. The horizontal plane (x) was defined through the right and left
orbitales and the right porion, and the frontal plane (y) was defined as the
perpendicular plane to x passing through two orbitale. The sagittal plane (z) was
defined by plane perpendicular to both x and y through Nasion (Figure 4). All
tracings and digitizations were made by 1 examiner (T.P) to minimize operator-
generated variation in the measurements.
Nine landmarks were digitized on each side of the cranium: Nasion,
Orbitale, Porion, Cementoenamel junction on the distal surface of the maxillary
second molar (CEJ 7), curvature of the maxillary tuberosity (Tub), Apex of the
palatal root of the maxillary second molar (Apex 7), alveolar crest of the distal
29

surface of the maxillary second molar (Alv Crest), most convex buccal surface of
the maxillary retromolar bone (Buccal bone), most convex lingual surface of the
maxillary retromolar bone (Lingual Bone) (Figure 5).
The software calculated the linear dimensions between certain landmarks
according to the definitions given in Table 2. Distance between two points were
measured on a reference plane and projected onto another reference plane.
Ten randomly selected subjects were reprocessed 1 weeks later to evaluate
intraoperator reliability. The intraclass correlation coefficients showed that the
measurements were extremely reliable (>0.9).

Statistical Analysis
Statistical evaluation was performed using IBM SPSS statistics 20.0 (IBM
Co., Armonk, NY). Normality was confirmed using the Shapiro-Wilk test. The
associations between group and gender, and between group and 3rd molar
presence were evaluated by Chi-square tests. Multivariate analysis of variance
(MANOVA) was performed to compare differences at the initial measurements
according to the occlusion classification and presence of 3
rd
molar. The
differences between pre- and post-treatment variables in the treated group were
assessed by paired t-tests. The post treatment measurements were compared
30

between those who received 3
rd
molars extraction and those with no change to
their dentition. Significance level was set at α=0.05.

31

Chapter 6. Results

Pre-treatment Class II Vs. Normal Occlusion Retromolar Dimensions
The mean and the standard deviation of maxillary retromolar bone
measurements (width, height, and length) for the pre-treatment class II
malocclusion group were as follows: 13.36 ± 2.06 mm, 7.86 ± 1.99 mm, 7.29 ±
3.14 mm. The values were not significantly different from that of the normal
occlusion group (12.98 ± 2.02 mm, 7.92 ± 1.96 mm, 7.88 ± 2.01 mm) (Table 3).
Effect of Presence of Third Molar on Pre-treatment Maxillary Retromolar Bone
Dimensions
Except for the width, which was significantly smaller in no third molar
group, there was no statistical difference in the retromolar bone height and
length between the 26 class II samples that had third molars pre-distalization and
the rest that either had congenitally missing third molars or had them extracted
prior to treatment. The result was the same for 30 normal occlusion samples that
had third molars pre-distalization compared to the 24 sample without third
molars (Table 4).

32

3D Measurements of the Maxillary Retromolar Bone Pre- Vs. Post- Distalization
The average distance distalized for treated cases was 2.72 mm, ranging
from 0.48 mm to 7.95 mm. After undergoing treatment, measurements of the
retromolar width, height and length significantly decreased to 12.08 ± 2.58 mm,
6.36 ± 2.21 mm and 5.14 ± 2.71 mm, respectively. Compared to the pretreatment
measurements, differences were 1.28 mm for width, 1.50 mm for height, and
2.15 mm for length (P value <0.001) (Table 5).
Retromolar Bone Remodeling Capacity
The mean pre-treatment bone length was 7.29 mm and the amount of
distalization was 2.72 mm. Thus, by subtraction, the remaining bone length is
expected to be 4.57 mm. However, the bone length post-treatment was
measured at 5.14 mm, suggesting overall bone length increase of 0.57 mm.
Paired t test showed the bone length increase to be statistically significant (P
value=0.021) (Table 6).
Distal Root Coverage
Bone coverage on the distal surface of the maxillary second molar was
analyzed by comparing the distance between alveolar crest to CEJ (CEJAlvCrest).
The mean CEJAlvCrest was 2.04 ± 1.33 mm for pre and 2.03 ±1.28 mm post
33

treatment. Statistically there was no significance difference in distal bone
coverage between pre- and post- distalization (Table 5).
Effect of Extraction of Third Molar on Post-Treatment Maxillary Retromolar
Bone Dimensions
There was no significant difference in post-treatment retromolar bone
dimensions and second molar distal bone coverage between class II subjects who
had third molar extraction performed after initiation of treatment versus subjects
who had no change to third molars (either had missing third molars to begin with
or kept their third molars throughout treatment) (Table 7).

34

Chapter 7. Discussion

The aim of this study was to evaluate the changes in the maxillary
retromolar alveolar bone dimensions and in bone coverage at the distal surface of
the maxillary second molar in response to MPAP assisted en-masse dental
distalization. Complete skull CBCT images were obtained for pre-and post-
treatment. Using Invivo 3D digitizing software, alveolar bone dimensions and
bone level relative to the CEJ at the distal surface of the second molar were
measured.
Standardized method to measure maxillary retromolar alveolar bone dimension
In this study, we described a method that can be used to obtain
reproducible and reliable three dimensional measurements of the maxillary
retromolar alveolar bone. The landmarks used in this study had good visibility
and were relatively easy to digitize in 3D. The linear measurements between two
specific digitized landmarks were programmed to be made on a preset reference
coordinate plane and projected to another reference coordinate plane that is
perpendicular to the first. For example, to obtain the width measurement, the
distance between the most convex point on the buccal and lingual plates were
measured on the FH plane, (X plane formed by two orbitale and right porion)
35

projected onto the Frontal plane (Y plane perpendicular to X plane through two
orbitale) (Table 2). Without this standardization procedure, the measurements
between two digitized points on a three dimensional frame would be completely
random (Figure 6). Using the above described method, it was possible to make
direct comparisons between class II and normal occlusion groups and between
two time frames of the class II group.
Changes to the Retromolar bone dimension after distalization
Anatomically, the maxillary retromolar alveolar bone tapers in width and
height as it gets closer to the pterygoid plate. Our study successfully
demonstrated this anatomical feature of the maxillary retromolar ridge. The post
distalization measurements of the retromolar bone were smaller in all three
dimensions compared to the pre-treatment values. This suggests that as
maxillary second molars are distalized, they run into bone that is smaller in all
dimensions than the bony housing at their initial position.
However, as in previous studies on osteogenic potential of orthodontically
distalized teeth, we also observed some bone remodeling at the leading end of
the retromolar bone to accommodate the distalized second molar. Although the
36

post-treatment bone length was smaller than pre-treatment, the overall total
bone length was found to be slightly greater (0.57 mm) than expected (Figure 7).
This result should be interpreted with caution because in this study the
length was measured at the CEJ level (CEJ to tuberosity curvature point) in order
to assess the bone remodeling capacity of the alveolar bone in this region. In
normal occlusion, maxillary second molars should have some degree of distal root
tip. Thus, to record the true retromolar alveolar bone length available for
distalization, it should be measured at the apical root level. At the apical root
level, the maxilla articulates with the pterygoid plate of the sphenoid bone; thus
there is little room for bone remodeling in non-growing patients. Bodily
movement of the maxillary second molar could still limited by the pterygoid plate.
If teeth are moved beyond the pterygoid plate, distal tipping will likely result.
Increased distal tipping of the crown may result in questionable post treatment
stability. Therefore, even if the crown can be distalized slightly beyond the
anatomical boundary with bone deposition, as in proclination of the anterior
teeth, it should be avoided.
In all 41 treated samples included in this study, there was a significant
amount of retromolar alveolar bone length remaining (5.14 ± 2.71 mm) after
37

distalization. Even if the measurements were made at the CEJ level, it can be
inferred that significant bone quantity remains at the root level as well. However,
this may not always be the case. When planning maxillary en-masse distalization,
the maxillary retromolar dimensions should be measured using the method
described in this study, but measuring the length at the apical root level. This
may assist in preventing distal crown tipping and periodontal defect.
Distal Root Coverage
The bone level at the distal surface of the maxillary second molar (CEJ
Alvcrest) was well preserved after distalization even when retromolar alveolar
bone height decreases and curves more apically as teeth move distally. This
phenomenon could be partially explained by the osteogenic potential of the
distalized second molar. The biomechanical explanation of the phenomenon is
that the maxillary second molar experienced intrusion as it was distalized. This is
congruent with the findings by Kook et al. who demonstrated an average of 1.8
mm of intrusion when distalizing with the MPAP appliance. With the MPAP
appliance, the distalizing force is applied at or more apical to the center of
resistance of the molar, thus allowing control of distal tipping and extrusion. The
intrusion of the molars during distal movement could help maintain the anterior
38

facial height, which is especially important for hyperdivergent patients (Kook et
al., 2014).
Another explanation for the maintenance of bone coverage at the distal
surface of the second molar is distal tipping of the crown rather than intrusion.
Kook et al. reported average of 3.4 ˚ of distal tipping with the MPAP. If only
intrusion had occurred, the post-treatment bone height, which was measured
from the alveolar crest to the apex of the palatal root of the second molar, should
have increased or at least have been maintained. However, in our study, the
bone height actually decreased by a statistically significant amount. Since other
factors that could have reduced the bone height, such as root resorption and
distal tipping, were not well controlled in this study, we cannot yet explain the
association between intrusion, bone height and distal bone coverage.
Management of Third Molars for Distalization
The definition of retromolar alveolar bone used in this study was the region
distal to the maxillary second molar. The same definition and landmarks for
measurements were used when third molars were present and it was considered
that the third molars were within the retromolar alveolar bone. The results
showed that presence of third molars did not affect the pre-treatment
39

dimensions of the retromolar alveolar bone; except for the width. The clinical
significance of this difference in width by 1.54 mm is yet to be studied but it is
possible that it may be negated by the osteogenic potential of the distalized
second molar. In other words, if the second molar maintains its width throughout
distalization by the process of bone remodeling, then the difference of 1.54 mm
in pre-treatment width should not matter. This study should be extended to
include comparison between the pre- and post-treatment width of the bony
housing directly surrounding second molar to answer the question whether
delaying maxillary third molar extractions for the purpose of preserving the
alveolar bone width is necessary.
The post treatment retromolar alveolar bone dimensions and second molar
distal bone coverage were not significantly different between samples that had
third molar extraction after initiation of the treatment versus subjects who had
no change to third molar (either had missing third molars to begin with or
retained their third molars throughout treatment). A study by Kook et al.
demonstrated that with the MPAP appliance, distalization in presence of third
molars do not affect the amounts of distalization or tipping. Given this
information, clinicians may defer the decision to extract the third molars to the
patients. However, when treating young adults with developing third molars, it
40

may be necessary to monitor the position of the developing or erupting third
molars and sometimes recommend extraction to avoid severe impaction during
maxillary dental distalization (Figure 8).
LIMITATIONS OF THE STUDY
Including the limitations already mentioned in the Discussion section, there
is room for improvement in the current study design.
Although previous studies demonstrated that craniometric measurements
made on CBCT scans is comparable to that of direct measurements made on dry
skulls, and the reliability for the current study measurements was greater than
0.9, the accuracy of digitizing landmarks in the maxillary alveolar region with such
low bone density is still questionable. Having one calibrated operator to perform
all digitization in a standardized setting could have reduced the effect of any
existing systemic error. Still, CBCT with a higher resolution is warranted for more
accurate and reliable measurements.
The inclusion criteria for the study samples could have been stricter for
better standardization. For example, the age range included in this study was
wide due to the limited number of patients that met the inclusion criteria. This
could have affected our result for the bone remodeling capacity of the maxillary
41

retromolar bone. It would be interesting to repeat this study using patients with
either active growth remaining, or patients with limited-to-no growth potential.

42

Chapter 8. Conclusion
As maxillary teeth are distalized, they move into bone that is smaller in the
dimensions of length, width and height. In all 41 treated cases, there was
sufficient bone length remaining post-distalization. Together with the observed
bone deposition at the leading end, it can be concluded that there is sufficient
retromolar bone length to accommodate maxillary dental distalization. This study
also showed that maxillary en-masse distalization with the MPAP appliance does
not lead to periodontal defects at the distal surface of the second molar.
However, further studies must be done to evaluate if there is active bone
remodeling in all three dimensions to maintain the bony housing around the
distalized second molar. It would be beneficial for clinicians to use the method
described in this study to assess the available retromolar alveolar bone when
planning maxillary en-masse distalization.

43

Figures and Tables
Figure 1. Distalization Appliances
A. Headgear (Angle, 1977)

B. Wilson Bimetric Arch (Nanda et al., 2005)

C. Pendulum Appliance (Caprioglio et al., 2015)

D. Jones Jig (Nanda et al., 2005)

44

E. Distal Jet (Nanda et al., 2005)

Figure 2. Skeletal Anchorage

A. Temporary Anchorage Device (TAD) (Tekale et al., 2015)

B. Zygomatic Anchorage Plate (Sugawara et al., 2006)

C. Modified Palatal Anchorage Plate (MPAP) (Kook et al., 2014b)

45

Figure 3. Maxillary Retromolar Bone

Maxillary Retromolar Bone is the region colored in red. It is mesially bordered by
the most distal molar (second molar in this study), and posteriorly bordered by
the pyramidal process of the palatine bone and pterygoid plate of the sphenoid
bone.

Figure 4. Reference Planes

Horizontal plane (x) was defined through the right and left orbitales and the right
porion, and the frontal plane (y) was defined as the perpendicular plane to x
passing through two orbitale. The sagittal plane (z) was defined by plane
perpendicular to both x and y.
46

Figure 5. Cephalometric Landmarks
(a)

(b)

47

(c) (d) (e)

(f) (g) (h)
Cephalometric landmarks and maxillary skeletal sagittal, vertical and horizontal measurements.
Landmarks: (a) Na, Nasion; Or, Orbitale; (b) Po Porion; CEJ 7 (c), Cementoenamel junction
(CEJ) on the distal surface of the maxillary second molar; Tub (d), curvature of the maxillary
tuberosity; Apex 7 (e), Apex of the palatal root of the maxillary second molar; Alv Crest (f),
alveolar crest of the distal surface of the maxillary second molar; Buccal bone (g), most convex
buccal surface of the maxillary retromolar bone; Lingual Bone (h), most convex lingual surface
of the maxillary retromolar bone.
48

Figure 6. Measurement Method: distance between two points on a plane and
projected onto a perpendicular reference plane.

B: buccal, L: Lingual, FH: Frankfort Horizontal Plane, Frontal: Frontal Plane

Figure 7. Illustration of difference between measured and expected length.

49

Figure 8. Severe Impaction of Developing Third molar

50

Table 1. Summary of Maxillary Dental Distalization Techniques
Distalization Technique/
(Reference for values)
Amount of Maxillary
Molar Distalized
Degree of Maxillary
Molar Tipping
Reciprocal
Anchorage
Loss
Caveats (italicized) /
Advantages (bolded)
Extraoral Traction
(Headgear)/ (Haydar et
al., 2000)
3.60 mm (cervical
headgear)
3.80 ˚ (cervical
headgear)
None Patient compliance
dependent / assist in
correction transverse
discrepancies and also
used to intrude or
extrude molars to the
provider’s advantage
(Nanda et al., 2005)
Wilson Bimetric Arch/
(Ucem et al. 2000)
3.5 mm 1.8 ˚
maxillary
incisor
protrusion,
proclination
and extrusion
with poor
patient
cooperation
39.8 % (1.38) mandibular
mesial movement from
interarch mechanic
(Muse et al.)
Pendulum/ (Caprioglio
et al., 2015)
4.7 mm 9.0 ˚
2.7 mm of
mesial
premolar
movement
5.0˚ incisor
proclination/
43%
anchorage loss
eruption of maxillary
second molar, extrusion
of first molars/ increase
in lower anterior facial
height and in Frankfort
mandibular plane angle
(Bussick and Mcnamara,
2000)
Jones Jig/ (Brickman et
al., 2000)
2.51 mm 7.53 ˚
2.0 mm of
mesial
premolar
movement,
4.75 ˚
premolar
mesial tipping
(Brickman et
al.)
Anchorage loss
significantly more than
the Pendulum appliance
(Patel et al.)
Distal Jet/ (Bolla et al.,
2002)
3.2 mm 3.1 ˚
1.3 mm of first
premolar
mesial
movement
and 3.1 ˚
mesial crown
tipping. 71%
molar
distalization
29 %
anchorage
loss.
Rate of distalization
slower than the
pendulum appliance.
Temporary Anchorage
Device (TAD)/ (Oh et al.,
2001)
1.4 mm to 2.0 mm 3.5 ˚
None 1 mm of posterior teeth
intrusion
Zygomatic Anchorage
Plate (Suguwara et al.,
2006)
3.78 mm Degrees not reported
but 3.20 mm root
movement
None Full mucoperiosteal flap
under IV sedation
Modified Palatal
Anchorage Plate
(MPAP)/ (Kook et al.,
2014)
3.3 mm 3.4˚
None 1.8 mm of molar
intrusion

51

Table 2. Measurement Definitions

Measurements Definition Projection Plane
BL Width Distance between buccal and lingual bone
on FH plane (x)
Frontal (y)
CEJ Alvcrest Distance between Alv crest and CEJ 7 on
Mid-sagittal plane (z)
Frontal (y)
Height at 7 Distance between Alv Crest and Apex 7 on
Mid-sagittal plane (z)
Frontal (y)
Bone Length Distance between Tub and CEJ 7 on Mid-
sagittal plane (z)
FH (x)
CEJ to Frontal Distance between CEJ 7 and Frontal Plane
(y)

Table 3. Comparison of class II and normal occlusion sample retromolar bone dimensions

(a) No significant association between gender and group

(b) No significant association between presence of third molars and group
(c) Comparison of class II and normal occlusion sample retromolar bone dimensions

52

Table 4. Effect of Presence of Third Molar in Pre-treatment Maxillary Retromolar Bone
Dimensions

Table 5. Comparisons of pre- and post-treatment measurements (n= 41)

Variables Pretreatment Posttreatment Change P Value
Mean
(mm)
SD Mean
(mm)
SD Mean (mm)

BL Width 13.36 2.06 12.08 2.58 1.28 P < 0.001
CEJ Alv crest 2.04 1.33 2.03 1.28 0.01 P = 0.429
Height at 7 7.86 1.99 6.36 2.21 1.50 P < 0.001
Bone Length 7.29 3.14 5.14 2.71 2.15 P < 0.001

Table 6. Bone Remodeling Capacity: Measured bone length vs. calculated bone length

Table 7. Effect of Extraction of Third Molar on Post-Treatment Maxillary Retromolar Bone
Dimensions

53

References

AGAR, U., DORUK, C., BICAKCI, A. A. & BUKUSOGLU, N. 2005. The role of psycho-social factors in
headgear compliance. Eur J Orthod, 27, 263-7.
AMERICAN DENTAL ASSOCIATION COUNCIL ON SCIENTIFIC, A. 2006. Dental management of patients
receiving oral bisphosphonate therapy: expert panel recommendations. J Am Dent Assoc, 137,
1144-50.
ANDERSON, J. A., BREWER, A., CREAGH, D., HOOK, S., MAINWARING, J., MCKERNAN, A., YEE, T. T. &
YEUNG, C. A. 2013. Guidance on the dental management of patients with haemophilia and
congenital bleeding disorders. Br Dent J, 215, 497-504.
BAILEY, L., CEVIDANES, L. H. & PROFFIT, W. R. 2004. Stability and predictability of orthognathic surgery.
Am J Orthod Dentofacial Orthop, 126, 273-7.
BALLANTI, F., LIONE, R., FANUCCI, E., FRANCHI, L., BACCETTI, T. & COZZA, P. 2009. Immediate and Post-
Retention Effects of Rapid Maxillary Expansion Investigated by Computed Tomography in
Growing Patients. The Angle Orthodontist, 79, 24-29.
BAYSAL, A., UYSAL, T., VELI, I., OZER, T., KARADEDE, I. & HEKIMOGLU, S. 2013. Evaluation of alveolar
bone loss following rapid maxillary expansion using cone-beam computed tomography. Korean J
Orthod, 43, 83-95.
BOLLA, E., MURATORE, F., CARANO, A. & BOWMAN, S. J. 2002. Evaluation of maxillary molar
distalization with the distal jet: a comparison with other contemporary methods. Angle Orthod,
72, 481-94.
BRANDAO, M., PINHO, H. S. & URIAS, D. 2006. Clinical and quantitative assessment of headgear
compliance: a pilot study. Am J Orthod Dentofacial Orthop, 129, 239-44.
BRICKMAN, C. D., SINHA, P. K. & NANDA, R. S. 2000. Evaluation of the Jones jig appliance for distal molar
movement. Am J Orthod Dentofacial Orthop, 118, 526-34.
BUSSICK, T. J. & MCNAMARA, J. A., JR. 2000. Dentoalveolar and skeletal changes associated with the
pendulum appliance. Am J Orthod Dentofacial Orthop, 117, 333-43.
CAPRIOGLIO, A., CAFAGNA, A., FONTANA, M. & COZZANI, M. 2015. Comparative evaluation of molar
distalization therapy using pendulum and distal screw appliances. Korean J Orthod, 45, 171-9.
CARANO, A. & TESTA, M. 1996. The distal jet for upper molar distalization. J Clin Orthod, 30, 374-80.
CATTANEO, P. M., TRECCANI, M., CARLSSON, K., THORGEIRSSON, T., MYRDA, A., CEVIDANES, L. H. &
MELSEN, B. 2011. Transversal maxillary dento-alveolar changes in patients treated with active
and passive self-ligating brackets: a randomized clinical trial using CBCT-scans and digital
models. Orthod Craniofac Res, 14, 222-33.
CHOI, Y. J., LEE, J.-S., CHA, J.-Y. & PARK, Y.-C. 2011. Total distalization of the maxillary arch in a patient
with skeletal Class II malocclusion. American Journal of Orthodontics and Dentofacial
Orthopedics, 139, 823-833.
COPE, J. B. 2005. Temporary anchorage devices in orthodontics: A paradigm shift. Seminars in
Orthodontics, 11, 3-9.
DALESSANDRI, D., LAFFRANCHI, L., TONNI, I., ZOTTI, F., PIANCINO, M. G., PAGANELLI, C. & BRACCO, P.
2011. Advantages of cone beam computed tomography (CBCT) in the orthodontic treatment
planning of cleidocranial dysplasia patients: a case report. Head Face Med, 7, 6.
DALESSANDRI, D., SALGARELLO, S., DALESSANDRI, M., LAZZARONI, E., PIANCINO, M., PAGANELLI, C.,
MAIORANA, C. & SANTORO, F. 2014. Determinants for success rates of temporary anchorage
devices in orthodontics: a meta-analysis (n > 50). Eur J Orthod, 36, 303-13.
EGGENSPERGER, N., SMOLKA, K., LUDER, J. & IIZUKA, T. 2006. Short- and long-term skeletal relapse after
mandibular advancement surgery. Int J Oral Maxillofac Surg, 35, 36-42.
54

FELDMANN, I. & BONDEMARK, L. 2006. Orthodontic Anchorage. The Angle Orthodontist, 76, 493-501.
FUHRMANN, R. A. W. 2002. Three-dimensional evaluation of periodontalremodeling during orthodontic
treatment. Seminars in Orthodontics, 8, 23-28.
GHOSH, J. & NANDA, R. S. 1996. Evaluation of an intraoral maxillary molar distalization technique. Am J
Orthod Dentofacial Orthop, 110, 639-46.
GRABER, T. M., VANARSDALL, R. L. & VIG, K. W. L. 2005. Orthodontics : current principles & techniques,
St. Louis, Elsevier Mosby.
GRIBEL, B. F., GRIBEL, M. N., FRAZÃO, D. C., JR, J. A. M. & MANZI, F. R. 2011. Accuracy and reliability of
craniometric measurements on lateral cephalometry and 3D measurements on CBCT scans. The
Angle Orthodontist, 81, 26-35.
HAN, S., BAYOME, M., LEE, J., LEE, Y.-J., SONG, H.-H. & KOOK, Y.-A. 2012. Evaluation of palatal bone
density in adults and adolescents for application of skeletal anchorage devices. The Angle
Orthodontist, 82, 625-631.
HAYDAR, S. & UNER, O. 2000. Comparison of Jones jig molar distalization appliance with extraoral
traction. Am J Orthod Dentofacial Orthop, 117, 49-53.
HILGERS, J. J. 1992. The pendulum appliance for Class II non-compliance therapy. J Clin Orthod, 26, 706-
14.
JONES, R. D. & WHITE, J. M. 1992. Rapid Class II molar correction with an open-coil jig. J Clin Orthod, 26,
661-4.
KAMBUROGLU, K., KOLSUZ, E., KURT, H., KILIC, C., OZEN, T. & PAKSOY, C. S. 2011. Accuracy of CBCT
measurements of a human skull. J Digit Imaging, 24, 787-93.
KANG, S., LEE, S.-J., AHN, S.-J., HEO, M.-S. & KIM, T.-W. 2007a. Bone thickness of the palate for
orthodontic mini-implant anchorage in adults. American Journal of Orthodontics and Dentofacial
Orthopedics, 131, S74-S81.
KANG, S., LEE, S. J., AHN, S. J., HEO, M. S. & KIM, T. W. 2007b. Bone thickness of the palate for
orthodontic mini-implant anchorage in adults. Am J Orthod Dentofacial Orthop, 131, S74-81.
KAU, C. H., RICHMOND, S., PALOMO, J. M. & HANS, M. G. 2005. Three-dimensional cone beam
computerized tomography in orthodontics. J Orthod, 32, 282-93.
KHECHOYAN, D. Y. 2013. Orthognathic surgery: general considerations. Semin Plast Surg, 27, 133-6.
KOKICH, V. G. 1996. Managing complex orthodontic problems: the use of implants for anchorage. Semin
Orthod, 2, 153-60.
KOOK, Y. A., BAYOME, M., MO, S. S., KIM, Y. & CHUNG, K. R. 2014a. Temporary skeletal anchorage
devices : a guide to design and evidence-based solution: Chapter 5 Modified Palatal Plate., New
York, NY, Springer Berlin Heidelberg.
KOOK, Y. A., BAYOME, M., TRANG, V. T., KIM, H. J., PARK, J. H., KIM, K. B. & BEHRENTS, R. G. 2014b.
Treatment effects of a modified palatal anchorage plate for distalization evaluated with cone-
beam computed tomography. Am J Orthod Dentofacial Orthop, 146, 47-54.
KOOK, Y. A., KIM, S. H. & CHUNG, K. R. 2010. A modified palatal anchorage plate for simple and efficient
distalization. J Clin Orthod, 44, 719-30; quiz 743.
MUSE, D. S., FILLMAN, M. J., EMMERSON, W. J. & MITCHELL, R. D. 1993. Molar and incisor changes with
Wilson rapid molar distalization. Am J Orthod Dentofacial Orthop, 104, 556-65.
NANDA, R. S., DANDAJENA, T. C. & NANDA, R. 2005. CHAPTER 9 - Biomechanic Strategies for
Nonextraction Class II Malocclusions. In: NANDA, R. (ed.) Biomechanics and Esthetic Strategies in
Clinical Orthodontics. Saint Louis: W.B. Saunders.
NETTER, F. H. 2010. Atlas of human anatomy, Philadelphia, PA, Saunders/Elsevier.
NGANTUNG, V., NANDA, R. S. & BOWMAN, S. J. 2001. Posttreatment evaluation of the distal jet
appliance. Am J Orthod Dentofacial Orthop, 120, 178-85.
55

OH, Y. H., PARK, H. S. & KWON, T. G. 2011. Treatment effects of microimplant-aided sliding mechanics
on distal retraction of posterior teeth. Am J Orthod Dentofacial Orthop, 139, 470-81.
PATEL, M. P., JANSON, G., HENRIQUES, J. F., DE ALMEIDA, R. R., DE FREITAS, M. R., PINZAN, A. & DE
FREITAS, K. M. 2009. Comparative distalization effects of Jones jig and pendulum appliances. Am
J Orthod Dentofacial Orthop, 135, 336-42.
PROFFIT, W. R., SARVER, D. M. & FIELDS, H. W. 2007. Contemporary orthodontics, St. Louis, Mo., Mosby
Elsevier.
REDDY, M. S., MAYFIELD-DONAHOO, T., VANDERVEN, F. J. & JEFFCOAT, M. K. 1994. A comparison of the
diagnostic advantages of panoramic radiography and computed tomography scanning for
placement of root form dental implants. Clin Oral Implants Res, 5, 229-38.
REYNDERS, R., RONCHI, L. & BIPAT, S. 2009. Mini-implants in orthodontics: A systematic review of the
literature. American Journal of Orthodontics and Dentofacial Orthopedics, 135, 564.e1-564.e19.
SA'AED, N. L., PARK, C. O., BAYOME, M., PARK, J. H., KIM, Y. & KOOK, Y. A. 2015. Skeletal and dental
effects of molar distalization using a modified palatal anchorage plate in adolescents. Angle
Orthod, 85, 657-64.
SENDAX, V. I. 2013. Mini dental implants : principles and practice, St. Louis, Mo., Elsevier.
SERGL, H., KLAGES, U. & ZENTNER, A. 2000. Functional and social discomfort during orthodontic
treatment - effects on compliance and prediction of patients' adaptation by personality
variables. The European Journal of Orthodontics, 22, 307-315.
SHILOAH, J., FRY, H. R., ABRAMS, M. E., BINKLEY, L. H. & TAYLOR, R. F. 1987. Soft tissue fenestration and
osseous dehiscence associated with orthodontic therapy. Int J Periodontics Restorative Dent, 7,
43-51.
SUGAWARA, J., KANZAKI, R., TAKAHASHI, I., NAGASAKA, H. & NANDA, R. 2006. Distal movement of
maxillary molars in nongrowing patients with the skeletal anchorage system. American Journal
of Orthodontics and Dentofacial Orthopedics, 129, 723-733.
TALASS, M. F., TALASS, L. & BAKER, R. C. 1987. Soft-tissue profile changes resulting from retraction of
maxillary incisors. Am J Orthod Dentofacial Orthop, 91, 385-94.
TANAKA, E., NISHI-SASAKI, A., HASEGAWA, T., NISHIO, C., KAWAI, N. & TANNE, K. 2008. Skeletal
Anchorage for Orthodontic Correction of Severe Maxillary Protrusion after Previous Orthodontic
Treatment. The Angle Orthodontist, 78, 181-188.
TEKALE, P. D., VAKIL, K. K., VAKIL, J. K. & GORE, K. A. 2015. Distalization of maxillary arch and correction
of Class II with mini-implants: A report of two cases. Contemp Clin Dent, 6, 226-32.
TRONJE, G., WELANDER, U., MCDAVID, W. D. & MORRIS, C. R. 1982. Image distortion in rotational
panoramic radiography. VI. Distortion effects in sliding systems. Acta Radiol Diagn (Stockh), 23,
153-60.
TWEED, C. H. 1944. Indications for the extraction of teeth in orthodontic procedure. Am J Orthod Oral
Surg, 42, 22-45.
UCEM, T. T., YUKSEL, S., OKAY, C. & GULSEN, A. 2000. Effects of a three-dimensional bimetric maxillary
distalizing arch. Eur J Orthod, 22, 293-8.
VANDENBERGHE, B., JACOBS, R. & YANG, J. 2008. Detection of periodontal bone loss using digital
intraoral and cone beam computed tomography images: an in vitro assessment of bony and/or
infrabony defects. Dentomaxillofac Radiol, 37, 252-60.
YARED, K. F., ZENOBIO, E. G. & PACHECO, W. 2006. Periodontal status of mandibular central incisors
after orthodontic proclination in adults. Am J Orthod Dentofacial Orthop, 130, 6 e1-8.
YU, I.-J., KOOK, Y.-A., SUNG, S.-J., LEE, K.-J., CHUN, Y.-S. & MO, S.-S. 2011. Comparison of tooth
displacement between buccal mini-implants and palatal plate anchorage for molar distalization:
a finite element study. The European Journal of Orthodontics.
56

ZACHRISSON, B. U. 2005. Bjorn U. Zachrisson, DDS, MSD, PhD, on current trends in adult treatment, part
2. Interview by Robert G. Keim. J Clin Orthod, 39, 285-96; quiz 315.

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Creator Park, Tina Keun Nan (author)

Core Title Three dimensional analysis of maxillary retromolar alveolar bone before and after en‐masse distalization

School School of Dentistry

Degree Master of Science

Degree Program Craniofacial Biology

Defense Date 02/05/2016

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag maxillary en‐masse distalization,modified palatal anchorage plate,OAI-PMH Harvest,orthodontics,retromolar bone

Format application/pdf (imt)

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Sameshima, Glenn (committee chair), Dan Grauer (committee member), Paine, Michael (committee member)

Creator Email tina.park.dds@gmail.com,tinakpar@usc.edu

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c40-218314

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Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the a...

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