Three-dimensional evaluation of soft tissue changes after mandibular setback surgery in class III malocclusion patients according to extent of mandibular setback, vertical skeletal pattern, and genioplasty

Abstract

Objective: To investigate the 3-dimensional (3D) changes in the soft tissue after mandibular setback surgery (MSS).

Study design: Thirty-three skeletal class III malocclusion (SCIII) patients treated with MSS (bilateral sagittal split ramus osteotomy) were subdivided according to extent of MSS, vertical skeletal pattern (VP), and vertical-reduction genioplasty. Lateral cephalograms and 3D facial scan images were taken before and 6 months after surgery. Linear and angular variables were measured with Rapidform 2006 (Inus Technology).

Results: After MSS, there were significant increases in the upper lip length and decreases in the lower lip length in the large setback, hypodivergent, and genioplasty groups. The mentolabial fold deepened less in the genioplasty group than in other groups. Although there was no skeletal advancement of the maxilla, the soft tissue convexity in the paranasal area increased more in the hyperdivergent group than in the hypodivergent group after MSS.

Conclusion: The extent of MSS, VP, and genioplasty could be used as guidelines for 1- and 2-jaw surgeries in SCIII borderline cases.