Abstract: Objective　 The purposes of this study were to evaluate facial asymmetry 3 dimensionally using cone beam computed tomography (CBCT) . Methods　 The CBCT datas of 30 malocclusion pattern with asymmetry (soft tissue menton deviation more than 4 mm distance from the facial midline),(mean age, 19.5years) and 30 pattern without asymmetry (soft tissue menton deviation less than 2 mm distance from the facial midline) (mean age, 19.9 years) were exported to the MIMICS software program (version 17.0). Linear distance, angular, volumetric, and surface area measurements were performed 3 dimensionally to assess and compare intragroup and intergroup differences. Results　 Z-Ag,ZA-Goinf,J-FML,J-N,Golat-Me,Co-Goinf,Gopost-FML,Golat-FML,Gopost-Me,Co-Me,P-N, MOP, MBP and the Golat-Me have significant differences between the deviated side and the undeviated side for the asymmetry pattern（P＜ 0.05) . J-FML、J-N 、Golat-FML have significant differences for the control. The volume and surface of mandibular have significant differences in asymmetry . Conclusions　 Asymmetry mainly be found in mandibular, especially in the gonial region. Facial hard and soft tissue asymmetries can be precisely quantified using CBCT,which is important for diagnosis and treatment.

Key words: Key words：　 cone beam computed tomography (CBCT), malocclusion, asymmetry , hard and soft tissues.