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

Introduction: The purpose of this study was to analyze the morphologic features of skeletal units in the mandibles of patients with facial asymmetry and mandibular retrognathism using cone-beam computed tomography. Methods: The subjects consisted of 50 adults with facial asymmetry and mandibular retrognathism, divided into the symmetry group (n = 25) and the asymmetry group (n = 25) according to the degree of menton deviation. Three-dimensional computed tomography scans were obtained with cone beam computed tomography. Landmarks were designated on the reconstructed 3-dimensional images. Linear and volumetric measurements were made on the mandibles. Results: In the asymmetry group, the lengths of condylar, body, and coronoid units were shorter, and condylar width was narrower on the deviated side than on the nondeviated side (P <0.01). The lengths of angular and chin units were not significantly different between the deviated and nondeviated sides (P >0.05). Hemimandibular, ramal, and body volumes were less on the deviated side than on the nondeviated side (P <0.01). Conclusions: Condylar, body, and coronoid units contribute to mandibular asymmetry in patients with facial asymmetry and mandibular retrognathism.