Hard and soft tissue changes after correction of mandibular prognathism and facial asymmetry by mandibular setback surgery: three-dimensional analysis using computerized tomography.

OBJECTIVE

To investigate the 3-dimensional (3D) changes in the hard and soft tissues of skeletal class III malocclusion (CIII) patients with or without facial asymmetry by mandibular setback surgery (MSS).

STUDY DESIGN

Seventeen adult CIII patients treated with MSS (bilateral sagittal split ramus osteotomy) who had 3D computerized tomography taken 1 month before (T0) and 6 months after (T1) MSS, were allocated into group 1 (symmetry, menton deviation (MD) <4 mm; n = 8) or group 2 (asymmetry, MD >4 mm; n = 9). The landmarks and variables were measured with Rapidform 2006 (Inus Technology).

RESULTS

Mandibular prognathism was significantly corrected in both groups. Facial asymmetry in group 2 was significantly corrected not only in the lower lip and chin but also in the philtrum deviation and mouth corner of the deviated side. The hard and soft tissue changes were more related in the horizontal and anteroposterior aspects than in the vertical one.

CONCLUSION

Three-dimensional evaluation showed a significant difference in the hard and soft tissue changes between symmetric and asymmetric MSS.