Evaluation of Bone Remodeling After Simultaneous Sagittal Split Ramus Osteotomy and Mandibular Angle Ostectomy in Patients With Mandibular Prognathism

Purpose: The present study assessed the postoperative bone remodeling after simultaneous sagittal split ramus osteotomy (SSRO) and mandibular angle ostectomy using a 3-dimensional analysis of computed tomography (CT) data. Materials and Methods: We designed and implemented a retrospective study that included patients who had undergone SSRO with (study group) or without (control group) mandibular angle ostectomy. Using CT data taken immediately after (T1) and 6 months (T2) after surgery, the vertical and horizontal morphologic changes of the mandibular angle were evaluated and compared between the 2 groups. In the study group, the volumetric changes of the mandibular angle were assessed, and the bone regeneration rate was calculated. Results: A total of 58 mandibular angles were evaluated (32 in the study group and 26 in the control group). The study group exhibited significantly greater vertical bone regrowth at the middle and posterior regions of the mandibular angle ostectomy line compared with that in the control group (middle, P<.001; posterior, P<.001). Both groups showed significant horizontal bone regrowth at 6 months postoperatively (P<.01). In the study group, the postoperative vertical bone regrowth was significantly associated with the extent of exposed bone below the angle ostectomy line at T1 for all regions (P<.001). The percentage of postoperative regenerated bone volume relative to the volume of bone removed intraoperatively was 41.8%. Conclusions: The present findings suggest that significant bone regrowth could occur after mandibular angle ostectomy with simultaneous SSRO. Therefore, it is necessary to consider bone remodeling patterns in the treatment planning stage for better and more predictable surgical outcomes. (C) 2020 American Association of Oral and Maxillofacial Surgeons