2014 AAO Annual Session Charley Schultz Resident Scholar Award
The Charley Schultz Resident Scholar Award program will be held on Saturday, April 26 in the Ernest N.
Morial Convention Center Room 356-357 from 1:00pm-2:00pm. Clinicians will be at their posterboards
during this time to answer questions about their research.
*- Denotes financial interest or visual enhancement
Basic Science Research
Genetic deactivation of TGF-β1 signaling attenuates articular cartilage degeneration in mature joints
Rebecca Chen
Harvard Univeristy
Background: Studies have shown conflicting roles of TGF-β1: disruption of the interaction of Tgf-β1 with
its receptor results in osteoarthritis (OA) joints in young mice; whereas others suggest of increased Tgf-β1
expression in mature joints causes early onset OA. The plausible explanation is that TGF-β1 signaling
acts in a developmental stage-dependent manner. This study aims to study role of TGF-β1 in OA
development. Method: With conditional knock out techniques, Tgfbr2 was removed from articular cartilage
of knee and TMJ in mature mice. Cartilage degeneration was induced by surgery. Joints at 4, 8 and 16
wks post-op (n=4 each) were collected for morphological analysis. Results: Initiation of articular cartilage
degeneration in the mature mice joints with genetic inactivation of Tgfbr2 was attenuated, when
compared to controls. Conclusion: Inhibition, instead of application, of TGF-β1 activity, may be
considered in OA treatment.
Optimal timing of bisphosphonate treatment on alveolar cleft bone grafting
Nicole Cheng
University of California, Los Angeles
Objectives: The aim was to investigate the optimal timing of Bisphosphonate (BP) injection on bone grafts
placed in defects in rats. Methods: 36 animals underwent surgical creation of an alveolar defect followed
by placement of an isograft from Inbred donors. The control group (n=8) was given a subcutaneous (sc)
injection of saline. Three experimental groups (n=8 per group) were given a sc injection of BP at either
the time of surgery, 1 week after surgery or 3 weeks after surgery. A negative control group (n=2) had a
defect created without bone graft, while a positive control group (n=2) did not have surgery. Animals were
euthanized at 6 weeks. Micro-CT and histological analysis were performed. Results: Percent bone
volume was significantly higher in delayed BP injection groups compared to controls and BP injection at
the time of surgery. Conclusions: A delayed one-time BP injection showed greatest bone healing in
comparison to injection at the time of surgery and the control.
Pure mandibular incisors intrusion? A finite element study to test the segmented arch technique
Gabriela de Brito
Pontific Catholic University
The purpose of this research was to evaluate different configurations of segmented arch mechanics
designed to achieve pure mandibular anterior teeth intrusion using the finite element method (FEM). A
FEM of the mandibular arch of an adult patient presenting deep bite was modeled with the SolidWorks
Software®. After all dental and periodontal ligament were graphically represented, brackets and wires
were modeled. Discretization and boundary conditions of the anatomical structures were determined with
the HyperMesh Software®. Twenty g of intrusive force were bilaterally applied with a cantilever in 4 points
of the intrusion base arch (IBA): FEM1 – at the IBA most anterior point; FEM2 – at the level of the mesiodistal center of the canine; FEM3 at the level of the canine’s distal surface; FEM4 at the level of the
mesio-distal center of the first premolar. The FEM 3 showed true mandibular incisor intrusion. FEM 1 and
2 resulted in buccal crown tipping of the incisors and FEM 4 generated lingual tipping tendencies.
Conclusion: FEM simulations indicated the ideal location of force application to achieve pure mandibular
incisors intrusion with segmented arch mechanics.
Occlusal plane manipulation effects on root angulation in CBCT derived pan-like images
Heather Green
Roseman University
Background: Panoramic radiographs remain the commonly accepted standard to assess root parallelism.
Given the limitations of 2D images, 3D derived pan-like images merit further study. Purpose: To examine
the effects of occlusal plane alteration in all 3D spatial orientations (X, Y & Z) on mesiodistal root
angulations. Research Design: A custom-made typodont with secured stainless steel pins representing
roots of maxillary and mandibular teeth in a Class I relationship with 0˚angulation was scanned (iCAT).
Using Dolphin imaging (version-11.5), 31 pan-like images and 806 angular measurements were
generated. Occlusal plane was altered at 2˚ increments up to ±10˚ along X, Y & Z axes and pan-like
images were generated for each plane. Results: Clinically significant measurements (>2.5˚) ranged from
2.6˚ to 5.4˚ primarily in the incisor and canine area. Conclusion: Generalized mesiodistal angulation
distortions were seen, with the most notable at incisors (X- axis) and canines (Z-axis).
Selective alveolar decortication an adjunct to tooth movement in bisphosphonate burdened bone
Neelambar Kaipatur
University of Alberta
Background: Orthodontic tooth movement (OTM) is significantly inhibited in bisphosphonate burdened
alveolar bone (BpBAb). Purpose: To investigate the effect of Selective Alveolar Decortication (SADc)
facilitated OTM on BpBAb in a rodent model. Research Design: Two groups of 10 rats each were
included and each group was pretreated for three months with either alendronate sodium (SADc+BP
burden group) or saline (SADc group). SADc surgery was performed on day 0 of appliance insertion.
OTM measurements were obtained at 0, 4, and 8 weeks using in-vivo µCT. Results: Our results showed
appreciable tooth movement of 0.38 mm and 0.93 mm in the SADc+BP burden group. In comparison,
SADc group showed 0.61 mm and 1.97 mm of tooth movement in 4 weeks and 8 weeks respectively.
Conclusion: This study demonstrated selective alveolar decortication as an adjunct to tooth movement in
a bisphosphonate burdened alveolar bone but the long term tissue effects of such an injury should be
further researched.
Force decay evaluation of thermoplastic and thermoset elastomers - A mechanical design comparison
Ahmed Masoud
University of Illinois, Chicago
Power chains (PCs) made from thermoplastic (TP) and thermoset (TS) materials are used
interchangeably in the literature and in clinical practice and to date no study has compared the two.
Objectives: To compare, over a period of 8 weeks, force decay between: (1) TP and TS PCs, (2) light and
heavy forces, and (3) direct chains and chain loops. Methods: TP and TS PCs were obtained from
American Orthodontics® (AOTP, AOTS) and ORMCO® (OrTP, OrTS). Each of the 4 PC groups was
subdivided into 4 subgroups: (1) direct chains light force, (2) direct chains heavy force, (3) chain loops
light force, and (4) chain loops heavy force. Results: A significant difference was found between TP and
TS PCs with approximately 20% more force decay in the TP groups. Direct chains had more force decay
compared to chain loops only in the OrTP group. Conclusion: Contrary to the analogous use of TP and
TS PCs, this study demonstrates that they perform differently and that a clear distinction should be made.
Biomechanical characterization of the periodontal ligament: Orthodontic tooth movement
Richard Uhlir
University of North Carolina, Chapel Hill
Purpose: The biomechanical characteristics of the periodontal ligament (PDL) are currently not
completely known. Method: A Dynamic Mechanical Analyzer that detects small forces at resolutions of
0.002 N was utilized to characterize stress-strain behavior of PDL specimens from mandibular bovine
incisors. Uniaxial tension tests with different force levels of 0.5, 1, and 3 N were completed for 37
samples. Modulus values were compared to see effects of anatomic location and force levels. The
Mooney-Rivlin Hyperelastic (MRH) model was used in a Finite Element Analysis (FEA) simulation of
orthodontic intrusion. Results: Force levels and anatomic location were statistically significant in their
effects on modulus. MRH approximated experimental data, and demonstrated reasonable expected
outcome of stress/strain levels in the PDL and bone for FEA intrusion simulation. Conclusion: The PDL is
non-homogeneous in which modulus changes in relation to location within the PDL and applied force.
Clinical Research
Genetic polymorphisms and its inheritance in skeletal Class I crowding in India
Shailesh Bhandari
NTR University
Dental crowding is a problem for both adolescents and adults, in modern society. The objective of this
research was to identify single nucleotide polymorphisms responsible for crowding and the inheritance
pattern from the parents to their offspring. 48 case subjects their both parents and 50 control subjects
were recruited. Case subjects consisted of healthy Indian people with skeletal Class I relationships and at
least 5mm of crowding in either arch. SNP genotyping was performed. Chi-square test, Logistic
regression, LD were performed.SNPs rs3764746 and rs3795170 on EDA gene (P=0.004) and SNP
rs1005464 (P=0.017) and rs15705 (P=0.031) in BMP2 gene were associated with crowding. Phenotype
segregating was determined by single dominant gene with incomplete penetrance (0.82). EDA and BMP2
genes were found to be associated with crowding. Crowding can be said to be a polygenic trait that
follows mendelian trait i.e. autosomal dominant with incomplete penetrance and variable expressivity.
The effect of chemotherapy on the survival of dental implants
Li-Ping Chew
Mayo Clinic
Individuals treated for head and neck cancer may require implants for oral rehabilitation. The aim of this
study was to determine if chemotherapy had an effect on the survival of dental implants. A retrospective
chart review was completed on Mayo Clinic patients who had chemotherapy and at least one dental
implant. Fifty-seven patients were evaluated. Two of the 57 patients experienced an implant failure.
Estimated survival free of implant failure rates by the Kaplan-Meier method at 1, 3 and 5 years for
patients with chemotherapy were 96%, 96% and 96%. Previous control groups using the Mayo Clinic
Implant Database have shown the survival-free of implant failure rate to be 96.6%, 95.4% and 94.5% at 1,
3 and 5 years respectively, suggesting no difference in the survival rate of implants in patients with or
without chemotherapy.
Assessment of intra/inter examiner reliability of the modified Huddart-Bodenham index in patients with
UCLP:a pilot study
Uchenna Ekwenibe
Lagos University
BACKGROUND- Treatment outcome evaluation is an integral part of patient management and a basis
for evidence based care delivery. This pilot study will provide preliminary data for further outcome
studies. PURPOSE-To assess the intra/inter examiner reliability of the modified Huddart-Bodenham index
in a Nigerian population. RESEARCH DESIGN-Ten dental casts of 6-10 years old with unilateral cleft lip
and palate(UCLP) were evaluated by two Orthodontists and an orthodontic resident. Spearman's(P) and
Kendall's tau(tc) rank correlation coefficients were used for intra and inter examiner reliability. RESULTSThere was substantial intraclass agreement consistently >0.7(Kendall) and > 0.8(Spearman) for all
examiners. The inter class agreement was between 0.5(lowest score) and 0.89(highest). CONCLUSIONThe index can be reliably used in occlusal assessment of patients with UCLP in a Nigerian population.
Assessment of the reliability of dental measurements using the OrthoMechanics Sequential Analyzer
Ahmed Ghoneima
Indiana University-Purdue University, Indianapolis
The aim of this study was to evaluate the reliability of newly developed software in the assessment of
orthodontic tooth movement three dimensionally. Methods: The sample consisted of pre and posttreatment computed tomography scans and dental models of 20 subjects. Dental parameters were
measured on the scans using InvivoDental imaging software v 5.1. Dental models were laser scanned
and measurements were obtained digitally using the new software. Agreement between digital and CT
measurements was evaluated using intraclass correlation coefficients (ICCs), paired t-tests, and BlandAltman plots. A p-value of ≤ 0.05 was considered statistically significant. Results: High agreement (ICC >
0.9), a non-significant paired t-test, and no indication of agreement discrepancies were observed for most
parameters. Conclusions: The software offers a reliable tool concerning dental arch measurements. It is
expected to help orthodontists evaluate treatment progress without unnecessary radiation.
Craniofacial morphometric analysis of individuals with X-linked hypohidrotic ectodermal dysplasia
(XLHED)
Alice Goodwin
University of California, San Francisco
Background: X-linked hypohidrotic ectodermal dysplasia (XLHED) is characterized by missing or
malformed skin, hair, sweat glands, teeth, and a distinct facial appearance. Purpose: To characterize
craniofacial morphology in subjects with XLHED by use of advanced 3D imaging and geometric
morphometrics. Research Design: 3D facial images of healthy male control subjects (n=59) and XLHED
subjects (n=23) were captured, landmarked, and analyzed. Results: The XLHED craniofacial phenotype
included shorter face with relatively longer chin and midface, prominent midfacial hypoplasia, protrusive
mandible, narrower and pointed nose, shorter philtrum, fuller and rounded lower lip, and narrower mouth.
Conclusions: 3D morphometric analysis is a powerful tool for clinical diagnosis of XLHED and has the
potential to be a more efficient and accurate tool than 2D cephalometrics in the orthodontic diagnosis and
treatment of individuals with XLHED and the general population.
Effect of palate height in tongue motion in glossectomy patients vs control*
Jun Hyuk Hwang
University of Maryland
Two types of /s/, apical and laminal, were identified in a previous study which showed that the palate
height affected the choice of /s/ in normal subjects, but not in post-glossectomy patients. Patients
predominantly used laminal /s/. Glossectomy patients often time develop abnormal motions of the tongue.
The aim of this study is to determine if glossectomy patients’ tongue mimic those of normal subjects with
high palate due to the increased amount of oral cavity space due to tongue resection. Using cine-MRI,
the relationship between height of the palate, dentition, and the tongue motion is analyzed during
production of phonemes “a-souk” and “a-geese”. The importance of palate height as well as dentition in
sound production may alter future therapy modality including the possibility of orthodontics as a possible
adjunctive treatment to improve acoustics of speech.
Patient compliance with orthodontic removable retainers: A pilot study
Paul Hyun
State University of New York, Buffalo
Although retainer compliance is out of the control of the provider, retainer wear may be improved with
microsensors. The objective was to compare retainer wear of 22 patients, one group aware of the Smart®
microsensor, and the other group unaware. The time periods were T0 (retainer delivery), T1 (6 weeks
visit), and T2 (12 weeks visit). At T1, the unaware group was informed of the sensor, and then returned at
T2 to evaluate any improvements. During T0 to T1, the average hrs/day for the aware group was 16.3,
while the unaware group was 10.6. The difference of 5.7 hrs/day was statistically significant. Although the
unaware group increased their retainer wear by 0.5 hr/day from T1 to T2, it was not statistically
significant. While 89% of subjects reported positive levels of comfort, the microsensor did increase the
palatal acrylic thickness. Although the Smart® microsensor provides a valid way to improve retainer wear,
certain changes could pave a more promising future for microsensors.
Influence of lower face vertical proportion on frontal facial attractiveness in Hispanics*
Elysa Kahan
Montefiore Medical Center
This study investigated the influence of changing lower anterior facial height (LAFH) in Hispanics on
attractiveness ratings scored by orthodontists and Hispanic laypersons using manipulated digital imagery.
Two sets of 9 digitized distortions were constructed from an initial male and female frontal image. LAFH/
total anterior facial height (TAFH) was varied in 2% increments from the normative values of 55±2%.
Friedman’s test and Spearman rank correlation coefficient validated the digitized distortion model. Images
with normal vertical proportions were rated most attractive by orthodontists, but female images 2% above
the norm were rated most attractive by Hispanic laypersons. Extreme deviations were unacceptable to
both groups. Female images with reduced LAFH were rated more attractive than corresponding images
with increased LAFH in both groups, with the reverse true in male images. LAFH/TAFH of 55% and 57%
are ideal facial proportions for Hispanic males and females, respectively.
Longitudinal 3-dimensional changes in dental arch form following orthodontic treatment
Josh Knowles
University of Texas, Houston
Objective: To evaluate the treatment and postretention differences in orthodontic patients classified
according to their initial arch form. Methods: The pretreatment, posttreatment, and postretention records
of 108 skeletal Class I orthodontic patients were matched based on pretreatment mandibular intercanine
widths. Extraction and nonextraction groups were subdivided according to the mandibular dental arch
form at T1: ovoid, tapered, or square. Transverse linear measurements were made between cuspids, first
premolars, and first molars for the three time periods on STL files. A surface registration analysis was
performed to measure the average linear differences at all points of the anatomic dental arch between T2
and T3. Results: Significant differences were observed for tapered and square arch forms when
compared to ovoid arches (p<0.05). Conclusions: Arch form changes and relapse in arch shape
predominantly occur in individuals with tapered and square arch forms.
Orthodontic marketing through social media networks: The patient and practioners’ perspective
Kristin Nelson
Virginia Commonwealth University
Objective: The aim of this study was to (1) assess the orthodontic patient and practitioner use and
preferences of social media, and (2) to investigate the potential benefit of social media marketing in
orthodontic practices. Methods: A survey was distributed to all participants, which included orthodontists
from the American Association of Orthodontists (AAO) and patients/parents from both Private Practice
and the VCU Orthodontic Clinic (VCU Practice). The participants were asked to answer questions related
to their use of social media as well as their perceptions of the usage of social media in the orthodontic
practice. Results: 76% of the orthodontist group, 71% of the VCU Practice group and 89% of the Private
Practice group used social media, with the highest preference for Facebook among all of the groups.
Facebook and Twitter were positively related to new patient counts.
Three dimensional shape analysis of facial and skeletal structures
Goli Parsi
Boston University
Objective: To establish a three-dimensional normative database by investigating the relationship between
shape and facial attractiveness using Geometric Morphometrics. Methods: A pixel-based patternrecognition model was used to rate attractiveness on 323 photographs of orthodontic patients. Ninety
eight hard tissue landmarks and semilandmarks were digitized on CBCT scans of most attractive and
least attractive groups. We used Geomorph add-on for shape comparisons and calculated an average
shape. Procrustes superimposition technique was used to compare random CBCT scans with the
average shape. Results: We found that the most attractive and the least attractive groups occupy different
areas in shape space and therefore are significantly different in shape at P<0.05. Geometric
Morphometrics proved to be a significant tool in analyzing facial and skeletal shapes and establishing a
baseline that can be used in diagnosis and planning of orthodontic and orthognathic surgical treatments.
Effect of aligner material and duration on orthodontic tooth movement
Neha Patel
University of Florida
SmartTrackTM, created by Align Technologies®, has a lower initial insertion force and a longer working
range compared to the older EX30 to aid orthodontic tooth movement (OTM). OBJECTIVES: To
investigate the effect of SmartTrackTM on OTM in-vivo over a 25-day period compared to EX30.
METHODS: Aligners made of one of the two materials and programmed for 0.25mm of buccal movement
of a maxillary incisor were used in 33 subjects (17 females and 16 males), 18-40 years old, for 22
hours/day for 25 days, in a randomized, blinded manner. RESULTS: SmartTrackTM achieved significantly
higher mean OTM (73.1%) compared to EX30 (42.8%) by Day 14. No difference in OTM occurred from
Day 14-25. Mixed modeling revealed SmartTrackTM and compliance separately provided 16% and 9%
higher OTM. CONCLUSION: SmartTrackTM achieved a higher mean OTM with a shorter lag phase
compared to EX30 over a 25-day period. A combination of SmartTrackTM effects and compliance play a
combined role in achievement optimal OTM.
Pediatric panoramic and cephalometric exposure to organs of the head and neck
Evanthia Peikidis
Stony Brook University
Limited research has been done using juvenile CIRS anthropomorphic phantoms and nanoDot Optically
Stimulated Luminescent Dosimeters (OSLDs) to measure absorbed doses imparted to children with
digital pan and ceph units. This study measured juvenile patient radiation dose to the organs of the head
and neck during digital pan and ceph radiography using juvenile CIRS phantoms at 5 and 10 yrs old with
nanoDot OSLDs. Juvenile CIRS phantoms for a 5 and 10 yr old were filled with nanoDot OSLDs placed at
21 organ sites. An Instrumentarium OP100D Orthopantomograph was used to expose the phantoms at
73kVp, 6.4mA, and 16.8s for pan imaging and at 85kVp, 12mA, and 17.6s for ceph imaging. Effective
radiation doses were calculated for all organs of the head and neck. Organ fractions were determined
from ICRP-89. Measured organ doses were higher for the 5 and 10 yr old for both pan and ceph. The
highest doses were in the glands, extrathoracic airway, and oral mucosa.
A limited volume CBCT orthodontic analysis to reduce patient radiation
Crystal Riley
Tufts University
Background: CBCTs have the ability to improve orthodontic diagnosis, but their use is limited due to
increased radiation. Purpose: In an effort to reduce radiation, limited CBCT scans were examined to
determine if sagittal and vertical skeletal analyses were possible. Method: Orthogonal projections of only
the maxilla and mandible were generated from full volume CBCT scans of 100 subjects. Using the limited
projections, an analysis was developed and compared to standard cephalometric analyses. The analysis’
ability to differentiate skeletal patterns was tested using Kruskal-Wallis/Mann-Whitney U. Results:
Measurements VR-MP and Ptm-Ba-MP were able to differentiate hypo-, normo-, and hyper-divergent
patterns (p≤.012), while AV-BV differentiated Class I, II, and III (p<.001). Most measurements and their
cephalometric counterparts had moderate to high correlation (r≥.565, p<.001). Conclusion: A limited
volume CBCT analysis can differentiate both sagittal and vertical skeletal patterns.
Lateral comparisons using Fishman’s skeletal maturation assessment
Abraham Safer
Maimonides Medical Center
Background: One way clinicians determine a patient’s skeletal maturation is by taking a hand-wrist
radiograph. This radiograph has been positively correlated with statural and facial growth. Purpose:
Lateral differences between ossification events and stages of bone development were assessed in the
hands and wrists using Fishman’s skeletal maturation indicators (SMIs). Research Design: The skeletal
ages of 125 subjects, aged 8-20 years, were assessed in both right and left hand-wrists. The data sets
were analyzed against each other, handedness, age and gender. Results: No significant overall
differences existed between right and left SMI scores (P = 0.70), regardless of handedness, gender, or
age. Yet, when categorized based upon SMI scores for the right hand-wrists, a significant difference (P =
0.01) existed between the SMI 1-3 and 11 groups. Conclusions: It is advisable to obtain a left hand-wrist
radiograph and/or additional diagnostic information to estimate completion of growth.
Comparison of linear measurements obtained from a CBCT, dental impressions and intra-oral scanning
Stephen Strickland
University of Alabama, Birmingham
Background New methods to capture the dentition have been developed including laser scanning of
physical study models, segmentation of the hard tissues in CBCT DICOM datasets and the use of photorealistic intra-oral scanning. Purpose Determine if digital models from CBCT images and intra-oral
scanning are comparable to traditional digital study models. Research Design 52 patient records were
gathered from the UAB orthodontic department. 26 had record of CBCTs and digital casts and 26 had
digital models from scanned models and from an Omni-CAM (R). Models were generated and 14 linear
measurements were made. Results Measurements of the two datasets were analyzed and no statistical
significance between the digital models in the two datasets was shown. Conclusions CBCT models and
intra oral scanned models are as accurate as laser scanned study models for linear measurements. This
study suggests these records meet the accuracy requirements to be used for diagnosis and treatment
planning.
Effect of orthodontic treatment on the upper airway volume
Isaac Tam
University of British Columbia
Introduction: Currently, the influence of orthodontic treatment on the volume of the upper airway is not
well understood. The aim of this study is to examine the effects of orthodontic treatment both with and
without extractions on the characteristics of the upper airway in adults. Methods: 3D analysis software
was used to segment and measure upper airway regions including the nasopharynx, the retropalatal and
retroglossal areas of the oropharynx, as well as total airway. Results: The treatment changes for all
airway regions examined were not significantly (p>0.05) different between the extraction and nonextraction groups. Similarly, changes in the minimum cross-sectional area were also not significantly
different between the two types of treatment. Conclusion: Orthodontic treatment in adults does not cause
clinically significant changes to the volume or minimally constricted area of the upper airway.
Cephalometrics and long-term outcomes of orthognatic surgery for obstructive sleep apnea
Elizabeth Ubaldo
University of Washington
Purpose: Describe skeletal, posterior airway and soft tissue after orthodontics and jaw surgery & correlate
advancement with long-term reduction in obstructive sleep apnea (OSA). Methods: Lateral cephs &
apnea-hypopnea index (AHI) after ortho and orthognatic surgery; patients completed a questionnaire to
assess long-term OSA. Linear regressions estimated final OSA in function of mandibular advancement.
Results: 43 patients with surgically advanced maxilla and mandible (5.2 mm and 8.3 mm) increased
posterior airway 4mm, and upper/lower lip 4.8 /7.6mm. In the long-term survey (6.3 years ± 2.6 after Tx)
90% had reduction of OSA and were pleased with facial appearance. Conclusions: Skeletal, soft tissue,
and posterior airway increased. Soft tissues were protrusive but with facial harmony. No evidence of
linear relationship between greater amounts of mandibular advancement and improvement of OSA.
Patients with less than10 mm advancement had successful short-term & long-term OSA reduction.
Candidate gene analyses of 3D dental phenotypes in patients with malocclusion
Cole Weaver
University of Iowa
Objectives: About 2% of the US population suffers from severe malocclusion discrepancies that are
beyond the limits of orthodontics alone. This study explores correlations between 3D malocclusion
phenotypes and craniofacial development genes. Methods: CBCTs (124) or digital casts (161) of 285
subjects with skeletal Class I (n=60), II (n=143) and III (n=82) malocclusion were digitized with 48 dental
landmarks. 3D coordinates were superimposed prior to Principal Component (PC) analyses to identify
symmetric (sym) and asymmetric (asym) aspects of shape variation related to malocclusion. PCs
explaining 51%-67% of total shape variation were regressed on 200 variants genotyped within 75 genes
adjusting for race, gender, age and data source. Results: Significant correlations (p<0.01) were found for
sym variation and BMP3, PITX2, SNAI3, ARHGAP29 and FGF8 and asym variation with PAX7, TBX1,
LEFTY1, SATB2, SOX2 and TP63. Conclusion: Results suggest genetic pathways associated with
malocclusion.
The effects of radiation dosage and variable scanning parameters on image quality
Aimee Zakaluzny
Tri-Service Residency Program
Background: CBCT radiation dose is affected by time, current, voxel size and field of view (FOV).
Alteration of these to reduce dose affects image quality. Purpose: Radiation dose and objective image
quality (OIQ) measurements were obtained using iCat Next Generation(R) and Planmeca ProMax 3D
Max(R). Images were assessed via subjective landmark identification. Research Design: MOSFET
detectors were used to calculate effective dosages (E) for Full FOV scans. OIQ was measured using
SendetexCT IQ CBCT phantom and anthropometric phantom was used for subjective image quality (SIQ)
by orthodontists. Results: E ranged 85-308 for iCat and 116-1072 µSv for Planmeca, increasing with scan
time. OIQ varied as a function of scan time/voxel size. SIQ revealed increased clinical utility with
increased dose/scan time. Conclusions: Increased scan times/higher radiation resulted in higher OIQ and
SIQ measures. However, orthodontists found images from high and low dose scans to be clinically
acceptable