Geometric Morphometry of the Midfacial Complex in Adult with Angle Class III Malocclusion

Autor: Ting-Shiuan Sung, 宋亭萱
Rok vydání: 2000
Druh dokumentu: 學位論文 ; thesis
Popis: 88
The purpose of this study was to evaluate whether the morphology of the midface differed in Angle Class I occlusion and Class III malocclusion adults, and to localize differences with finite-element method and thin-plate spline analysis. This study comprised lateral cephalographs of 100 adult Taiwanese with Angle Class I occlusion (50 female and 50 male), and 100 adult Taiwanese with Angle Class III malocclusion(50 female and 50 male). The cephalographs were traced, and 9 homologous landmarks were identified and digitized. The student t-test was used to analyze 12 linear and angular measurements for the evaluation of the differences between Class I and Class III subjects. The average configuration of each group was generated by the Procrustes analysis. The average configurations were employed with geometric morphometry: finite-element method and thin-plate spline analysis. The results of student t-test showed the posterior horizontal length of the midface (PNS-MPP and PtmS-Or) of Class III malocclusion subjects were reduced, and the anterior alveolar angle (ANS-A-Pr) and midfacial angles (PtmS-Rh-A and PtmS-Rh-Pr)were reduced also. The results of finite-element method were evident that there were size- and shape- changes between the midfacial configuration of the Class I and Class III subjects. Size changes demonstrate that negative allometry presented in the posterior region of the Class III midfacial complex. Shape changes demonstrate that the anisotropy localized in the subspinal region (ANS-A) and anterior-superior area of the midface. Thin-plate spline presented the retrusion of the palatomaxillary complex and downward deformation of the Rhinion. Due to these differences, the Class III malocclusion adults presented retrognathic profile of the midfacial complex, inferior displacement of the nasal tip, and proclined maxillary dentoalveolar process.
Databáze: Networked Digital Library of Theses & Dissertations
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