Document Type

Thesis

Date of Degree

Spring 2014

Degree Name

MS (Master of Science)

Degree In

Orthodontics

First Advisor

Lina M. Moreno

Abstract

Background: Nonsyndromic cleft lip and palate (NSCL/P) is a complex trait caused by genetic and environmental factors that interact producing a wide spectrum of orofacial malformations, including dental anomalies. The underlying genetic etiology that accounts for phenotypic variation in affected families is poorly understood. Purpose: The purpose of this study is to utilize shape and microesthetic analysis to characterize the maxillary anterior dentition in unaffected parents of children with NSCL/P (cases) compared to control adults with no CL/P history to identify dental morphology features that are part of the NSCL/P phenotypic spectrum and can therefore be used in refining NSCL/P phenotypes and identifying genetic risk factors. Methods: Individuals were recruited from 5 sites including Iowa, Texas, Hungary, the Philippines, and Pittsburg, PA. From a total of 3202 individuals, 420 quailified after strict selective criteria. Digital photographs from 198 cases and 222 controls were analyzed using linear metrics and 2D-coordinate landmark-based geometric morphometrics (GM) to compare dental esthetics and deviations from golden proportions." Differences in central incisor and connector height proportions were evaluated using paired T-tests. Anterior tooth shapes were examined using GM techniques. Results: Three shape differences were found to be possible predictors of genetic risk. These included shorter maxillary anterior teeth overall, square shaped lateral incisors on the left side, as well as lateral incisors and canines with long axes angled inward toward the midline on the left side. Both the case and control groups were found to be significantly different than the proposed ideal values of tooth proportions. Conclusions: Significant differences in anterior dental morphology were found between cases and controls, with controls displaying a more ideal dental morphology than cases for most evaluated measures. The identification of these distinct dental features in carriers of NSCL/P genetic risk factors further characterizes the phenotypic spectrum of NSCL/P which can enhance the power of genetic studies.

Keywords

Cleft Lip and/or Palate, Geometric Morphometrics, Golden Proportion, Microesthetics

Pages

viii, 84 pages

Bibliography

Includes bibliographical references (pages 80-84).

Copyright

Copyright 2014 Chloe M.E. Meier

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