Abstract:

Objective To analyze the condylar and inclination of the occlusal plane features in skeletal Class Ⅲ malocclusion patients with mandibular asymmetry by using cone beam computed tomography(CBCT). Methods Forty eligible patients with Angle Class Ⅲ malocclusion were enrolled. All individuals were classified based on the distance from Me point to median sagittal plane. The left and right angles between OP and FH plane, the position and morphology of the condyle were measured in both groups.Then the data collected were statistically analyzed. Results Compared to the opposite side, there was a statistically significant difference(P<0.05) in angle between OP and FH plane, the anterior joint space, superior joint space, lateral joint space and condylar mediolateral diameter, with a higher proportion of joint posteriority in deviated side. Mandibular deviations were positively correlated with both the anterior joint space of the deviated side and the angle between OP and FH plane of the opposite side(P<0.01). There was no statistical difference between the left and right side of angles between OP and FH plane, the position and morphology of the condyle in skeletal Class Ⅲ patients without mandibular deviation(P>0.05); the joint was predominantly in anterior and middle position. Conclusion There is asymmetry on the left and right sides of the inclination ofocclusal plane, the position and morphology of the condyle of skeletal Class Ⅲ malocclusion patients with mandibular asymmetry. Compared with the opposite side, the deviated side has smaller angle between OP and FH plane and smaller condylar mediolateral diameter, and the condyle shows generally more posterior, inferior and inward movement in glenoid fossa. The inclination of the occlusal plane and the position of condyle are significantly and positively correlated with the distance from Me point to median sagittal plane.

Key words: skeletal Class Ⅲ malocclusion, mandibular asymmetry, occlusion plane, condyle