Effect of Pterygomasseteric sling shortening via mandibular angle resection on postoperative skeletal stability in skeletal class III malocclusions treated with mandibular setback surgery.

Postoperative skeletal stability issues are frequently attributed to the tension exerted by the pterygomasseteric muscle sling following mandibular setback. This study investigated the hypothesis that simultaneous mandibular angle resection during Bilateral Sagittal Split Ramus Osteotomy (BSSRO) enhances skeletal stability by reducing this muscular tension. A prospective randomised controlled study was conducted on 20 patients with Skeletal Class III malocclusion - characterised by mandibular prognathism. The study sample was equally divided into an experimental group (4 males, 6 females; mean age 23.6 ± 3.9 years) undergoing the combined procedure (BSSRO with simultaneous mandibular angle ostectomy), and a control group (5 males, 5 females; mean age 20.4 ± 3.4 years) receiving isolated ramus osteotomy (conventional BSSRO setback only). Lateral cephalometric tracings were utilised to quantify the horizontal and vertical positional changes of the mental region, specifically at Point B, Pogonion and Menton, during the 3-month postsurgical healing phase. The results indicated a significant divergence in remodelling between the two groups. The control group characterised anterior relapse (B: +1.35 ± 1.50 mm; Pog: +0.81 ± 2.92 mm), whereas the experimental group demonstrated a stabilising posterior settling effect (Point B: -1.44 ± 1.93 mm; Pog: -1.14 ± 4.06 mm). These findings substantiate that resecting the mandibular angle effectively shortens the pterygomasseteric sling, thereby alleviating the muscular tension responsible for skeletal rebound. Consequently, simultaneous angle ostectomy during Surgery-First Orthognathic Approach (SFOA) mandibular setback protocol is advocated not merely as an aesthetic contouring procedure for lower facial width reduction, but as a functional release of the pterygomasseteric sling that significantly improves early skeletal stability, suggesting a larger study with Class II malocclusions as well or other types of skeletal deformity.