Postsurgical Relapse in Class III Patients Treated With Two-Jaw Surgery: Conventional Three-Stage Method Versus Surgery-First Approach

The aim of this study was to investigate the pattern, amount, and distribution of postsurgical relapse in skeletal Class III patients treated with two-jaw surgery (TJS) using conventional three-stage method (CTM) and surgery-first approach (SFA). A total of 38 patients who underwent the nonextraction approach and TJS (LeFort I posterior impaction and mandibular setback) were divided into CTM and SFA groups (all n=19/group). Lateral cephalograms were taken before treatment (T0), at 1 month before surgery (T1), immediately after surgery (T2), and at debonding (T3) for CTM patients and at T0, T2, and T3 stages for SFA patients. Cephalometric measurements and statistical analyses were performed. There were no significant differences in the cephalometric variables at all stages except maxillary incisor inclination (U1-UOP) and overbite at T0 between 2 groups. They also did not exhibit significant differences in the amounts of surgical movement except for advancement of the maxilla. The mandible in both groups was rotated slightly clockwise by surgery and counterclockwise during T2-T3 without a significant difference. Distribution of cases with high relapse (>30%) and low relapse (<30%) of the mandible differed for 2 groups (P<0.05). SFA group had more high relapse cases than CTM group (57.9% versus 26.3%). Postsurgical relapse of the mandible had a positive relationship with the amount of mandibular setback in SFA group (P<0.01) and clockwise rotation of the proximal segment of the mandible in both groups (P<0.05 and P<0.01). The results suggest that SFA might be an effective alternative to CTM if the cause of high relapse including amounts of mandibular setback and clockwise rotation of the proximal segment of the mandible during surgery can be controlled.