Three-dimensional computed tomography analysis of mandibular morphology in patients with facial asymmetry and mandibular prognathism.

Abstract

INTRODUCTION: The purpose of this study was to investigate the dimensional changes in each skeletal unit in the mandibles of patients with facial asymmetry and mandibular prognathism.

METHODS: The patients consisted of 50 adults with mandibular prognathism, divided into the symmetry group (n = 20) and the asymmetry group (n = 30) according to the degree of menton deviation. Three-dimensional computed tomography scans were obtained with a spiral computed tomography scanner. Landmarks were designated on the reconstructed 3-dimensional surface models. The lines to represent condylar, coronoid, angular, body, and chin units were used. Ramal and body volumes were measured in the hemi-mandibles.

RESULTS: In the asymmetry group, condylar and body unit lengths were significantly longer, and coronoid unit length was significantly shorter on the nondeviated side than on the deviated side (P <0.01). Angular and chin unit lengths were not significantly different between the 2 sides (P >0.05). Ramal volume was significantly greater on the nondeviated side (P <0.01), but body volume was not significantly different between the 2 sides (P >0.05).

CONCLUSIONS: Both condylar and body units appeared to contribute to mandibular asymmetry, with a more central role of the condylar unit.