[Maxillofacial 3-dimensional morphological analysis for patients with Class III malocclusion and facial asymmetry]

To investigate the skeletodental factors relating to the chin point deviation of facial asymmetry in skeletal Class III malocclusion patients using three-dimensional computed tomography.

Forty-one adult female patients with class III malocclusion, who underwent three-dimensional CT examination before orthodontics treatment, were assigned as group of symmetry or group of asymmetry according to the amount of chin point deviation from the facial midline. Midfacial and mandibular variables were measured. The data was analyzed with SPSS13.0 software package.

Patients in the group of asymmetry showed higher positions of the upper canine and first molar, shorter ramus height, more superior positioning of gonion on the deviated side, more mesial and frontal inclination of the ramus, medial and frontal positioning of gonion on the opposite side than the group of symmetry. Menton deviation correlated significantly with the difference of ramus height between the 2 sides ramus, ramus height in the deviated side and other skeletodental factors.

Facial asymmetry in Class III patients is due to the overgrowth,frontal and mesial inclination of the ramus in the opposite side.