Stability and outcome after two approaches for counterclockwise mandibular setback in patients with skeletal class...

Patients of skeletal class III high-angle malocclusion have different clinical entities. This prospective study aimed to compare stability and outcomes following two approaches for counterclockwise mandibular setback in bimaxillary rotational surgery to correct skeletal class III high-angle malocclusion. Fifty-six adult patients with skeletal class III high-angle malocclusion who underwent surgery-first bimaxillary surgery with counterclockwise mandibular setback were analyzed. Patients were grouped by different direction of mandibular distal segment: posterior-shortening (n = 25) and posterior-lengthening (n = 31). Measures from CBCT scans compared changes from pre-treatment (T0) to surgical simulation (Ts), 1-week post-surgery (T1), and post-treatment (T2), which included translation (left/right, posterior/anterior, superior/inferior) and rotation (yaw, roll, pitch). Outcomes were compared for jaw projection, incisor angle and occlusion. Pre-treatment, frequency was greater for gummy smile and smaller for maxillary and mandibular projection and overbite for the posterior-shortening compared with the posterior-lengthening group. Changes in both groups from pre-treatment were seen for backward and anterior upward movement with counterclockwise pitch rotation of the mandible (Ts); relapse in mandibular vertical translation and pitch (T1); and significant sagittal relapse of the mandible (T2). Most treatment outcomes at post-treatment were similar for posterior-shortening and posterior-lengthening groups; however, the posterior-shortening group had a significantly smaller maxillary and mandibular projection and upper incisor angle. The results of this study indicate that despite post-surgical relapse, both posterior-shortening and posterior-lengthening approaches to counterclockwise mandibular setback are effective strategies for correcting skeletal class III high-angle malocclusion, achieving both aesthetic and functional goals when tailored to individual skeletal and occlusal characteristics.