Chin-Soo Kim1, Sang-Chang Lee2, Hee-Moon Kyung3, Hyo-Sang Park3, Tae-Geon Kwon4. 1. Professor, Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu, Korea. 2. Resident, Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu, Korea. 3. Professor, Center for Orthognathic Surgery, Department of Orthodontics, School of Dentistry, Kyungpook National University, Daegu, Korea. 4. Professor, Center for Orthognathic Surgery, Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu, Korea. Electronic address: taegeonkwon@gmail.com.
Abstract
PURPOSE: The purpose of this study was to compare stability after mandibular setback surgery in patients with skeletal Class III malocclusion with and without presurgical orthodontics. MATERIALS AND METHODS: This retrospective cohort study included consecutive patients with skeletal Class III malocclusion who underwent only mandibular surgery. Patients treated with the surgery-first approach without presurgical orthodontics (SF group) were compared with a control group (conventional surgery with presurgical orthodontics; CS group) using lateral cephalograms taken preoperatively, immediately postoperatively, and at the time of debonding. Predictor variables (group and timing), outcome variables (cephalometric measurements over time), and other variables, such as baseline characteristics, were evaluated to determine the difference in stability of mandibular positions such as the B point. RESULTS: Sixty-one patients were enrolled in this study (CS group, n = 38; SF group, n = 23). Baseline demographic variables were similar in the 2 groups except for orthodontic treatment period. The mean setback of the mandible at the B point was similar (CS group, 8.7 mm; SF group, 9.1 mm; difference, P > .05), but the horizontal relapse in the SF group (2.4 mm) was significantly greater than in the CS group (1.6 mm; P < .05). Patients with a horizontal relapse greater than 3 mm comprised 39.1% of the SF group compared with 15.8% of the CS group (P < .05). CONCLUSION: Mandibular sagittal split ramus osteotomy without presurgical orthodontic treatment was less stable than conventional orthognathic surgery for mandibular prognathism. Before performing a surgery-first approach, skeletal stability needs to be considered.
PURPOSE: The purpose of this study was to compare stability after mandibular setback surgery in patients with skeletal Class III malocclusion with and without presurgical orthodontics. MATERIALS AND METHODS: This retrospective cohort study included consecutive patients with skeletal Class III malocclusion who underwent only mandibular surgery. Patients treated with the surgery-first approach without presurgical orthodontics (SF group) were compared with a control group (conventional surgery with presurgical orthodontics; CS group) using lateral cephalograms taken preoperatively, immediately postoperatively, and at the time of debonding. Predictor variables (group and timing), outcome variables (cephalometric measurements over time), and other variables, such as baseline characteristics, were evaluated to determine the difference in stability of mandibular positions such as the B point. RESULTS: Sixty-one patients were enrolled in this study (CS group, n = 38; SF group, n = 23). Baseline demographic variables were similar in the 2 groups except for orthodontic treatment period. The mean setback of the mandible at the B point was similar (CS group, 8.7 mm; SF group, 9.1 mm; difference, P > .05), but the horizontal relapse in the SF group (2.4 mm) was significantly greater than in the CS group (1.6 mm; P < .05). Patients with a horizontal relapse greater than 3 mm comprised 39.1% of the SF group compared with 15.8% of the CS group (P < .05). CONCLUSION: Mandibular sagittal split ramus osteotomy without presurgical orthodontic treatment was less stable than conventional orthognathic surgery for mandibular prognathism. Before performing a surgery-first approach, skeletal stability needs to be considered.