OBJECTIVE: This study attempts to characterize CIII malocclusion phenotypes in order to identify distinct subgroups for which genetic susceptibility could be identified. METHODS: Sixty-three lateral cephalometric variables were measured from pre-treatment records of 292 CIII Caucasian adults. Principal component analysis (PCA) and cluster analysis (CA) were used to identify the most homogeneous groups of individuals representing distinct CIII phenotypes and thus reducing genetic heterogeneity. RESULTS: PCA resulted in 6 principal components that accounted for 81.17% of the variation. The first three components represented variation on mandibular and maxillary horizontal and vertical position and lower incisor angulation, respectively. The cluster model identified 5 distinct subphenotypes of CIII malocclusion. CONCLUSIONS: A spectrum of phenotypic definitions was obtained which may enhance the identification of human susceptibility genes underlying CIII malocclusion.

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 with BMP3, PITX2, MAFB, SNAl3, FGF8, ABCA4-ARHGAP29, FOXL2 and asym variation PAX7, TBX1, LEFTY1, SATB2, SOX2, TP63 and the 400Kb region containing D1S435. Conclusion: Results suggest genetic pathways associated with malocclusion.

The mandible is able to move in a complex fashion, with variable combinations of both translation and rotation in three dimensions (six degrees of freedom), at any given time during function. Research into the process of accurately capturing three-dimensional functional movement of the mandible has many broad clinical applications in dentistry and medicine alike. Anatomical kinematics of the craniofacial skeleton that includes motion analysis has potential scope for clinicians in the areas of diagnostics, treatment planning and treatment outcome assessment. The aims of this study were to describe mandibular motion during opening-closing tasks of two adult subjects and one growing subject with a Class II malocclusion, undergoing growth modification with a Clark Twin Block appliance. Motion analysis recordings were taken with the use of a twelve-camera motion analysis system (Motion Analysis Corporation). The values of the kinematic variables (translation [millimeters] and rotation [degrees]) of mandibular opening-closing that were obtained were consistent and repeatable for both adult subjects throughout this study. In contrast, those values obtained from the subject who wore a functional appliance show noticeable changes in the motion patterning during the initial stages (recordings taken at four and at eight weeks) of appliance wear. These are most apparent in the translation data recorded along the anterior-posterior axis. Mandibular motion however, seemed to return to near pre-treatment patterning in this individual following one year following the initiation of the appliance wear. These observations were seen in one experimental individual. Further research is needed to elucidate whether such changes in motion patterning are seen normally in the growing individual, or, are accountable due to the clinical intervention with an orthodontic appliance. This study piloted the use of two different splint designs for the purposes of recording mandibular motion in the two adult subjects. There were no significant differences in the recording of mandibular motion between the two different splint designs. One design has been recommended for future studies due to its overall ease of fabrication and intra-oral comfort for the subjects.

published_or_final_version / Dentistry / Master / Master of Orthodontics

Thesis (M.S.)--University of Michigan, 1975.

Thesis (Ph. D.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Thesis (M.S. )--University of Tennessee Health Science Center, 2008. / Title from title page screen (viewed on July 25, 2008). Research advisor: Edward Harris, Ph.D. Document formatted into pages (xvi, 294 p. : ill.). Vita. Abstract. Includes bibliographical references (p. 169.182).

Thesis (M.S.)--University of Michigan, 1975.

Thesis (M.S.)--University of Michigan, 1966.

Thesis--University of Oslo, 1993. / Includes bibliographical references.