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

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.