Abstract
The aim of the present study was to clarify morphological differences in mandibular condyles between deviated and non-deviated sides and the spatial position of the mandible on craniomaxillary complex in a three-dimensional manner in facial asymmetry cases. A virtual reality model reconstructed from 30 patients with facial asymmetry was used in this study. The virtual reality model was segmented into two components, craniomaxillary complex and mandible, and two coordinate systems, global and local, were established in two segmented components for each of the two components. As geometric features of these virtualized models, the position and attitude of the mandible relative to the craniomaxillary complex, which represent the degree of facial asymmetry, and the angle and length of the condylar long axis, which represent the condylar morphology, were extracted. Condylar morphology was compared between the deviated and non-deviated sides. Furthermore, correlations between degrees of facial asymmetry and differences in condylar morphology between the deviated and non-deviated sides were examined. The results were as follows: (1) the length of the condylar long axis on the deviated side was significantly smaller than that on the non-deviated side; (2) the difference in the length of the condylar long axis increased with an increase of lateral deviation of the mandible; (3) the angle of the condylar axis on a Md axial plane on the deviated side was significantly larger than that on the non-deviated side; and (4) the difference in angle of the condylar long axis tended to increase with an increase of relative attitude of the mandible toward craniomaxillary complex on the axial plane. The results obtained from the 3D analysis method for which a reference coordinate system was established in the mandible itself indicated close relationships between bilateral morphological differences in the condyles and facial asymmetry.
