Changes in the Gonial Angle Following Bimaxillary Osteotomy
Abstract
Introduction: The aim of this study was to evaluate changes in the gonial angle (GA) after bilateral sagittal split ramus osteotomy (BSSRO) combined with Le Fort I osteotomy in Class II and Class III patients, and to compare the outcomes between the two groups. Materials and Methods: In this retrospective cohort study, 48 patients (21 Class II, 27 Class III) from Tehran University of Medical Sciences were included. All patients underwent bimaxillary osteotomy with rigid internal fixation using miniplates. Lateral cephalograms were used to measure the GA and occlusal plane angle (OPA) preoperatively, one day postoperatively, and 12 months postoperatively. Changes were analyzed using paired t-tests within groups and independent t-tests between groups. Pearson’s correlation was used to assess the relationship between GA and OPA changes. Results: The mean reduction in GA at 12 months was 2.81° (±2.89°) in Class II and 3.81° (±2.60°) in Class III patients. The mean relapse (increase) in GA from the first postoperative day to 12 months was 1.57° (±1.60°) in Class II and 2.00° (±1.41°) in Class III patients. No statistically significant difference was found between the two groups for the magnitude of GA change or relapse (p > 0.05). Furthermore, no significant correlation was found between the amount of GA change and OPA change within either group (p > 0.05). Conclusion: Bimaxillary osteotomy with rigid fixation resulted in a significant reduction of the gonial angle in both Class II and Class III patients. Although the magnitude of change and relapse was numerically greater in Class III patients, the difference was not statistically significant. The occlusal plane angle changed in a similar direction but was not strongly correlated with the gonial angle change. Keywords: BSSO; Gonial angle; Occlusal plane angle; Bimaxillary osteotomy; Miniplate fixation.
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8. Kang SH, Kim TJ, Shin HK. A CLINICAL STUDY OF CHANGES IN GONIAL ANGLE BETWEEN PRE-AND POST-ORTHOGNATHIC SURGERY IN MANDIBULAR PROGNATHIC PATIENTS. Journal of the Korean Association of Oral and Maxillofacial Surgeons. 1998;24(2):193-7.
9. Kwon YH, Jang HJ, Lee SH. CLINICAL ANALYSIS OF GONIAL ANGLE CHANGE AFTER ORTHOGNATHIC SUGERY IN PATIENTS WITH THE MANDIBULAR PROGNATHISM. Journal of Korean Association of Maxillofacial Plastic and Reconstructive Surgeons. 2000;22(2):206-16.
10. JAFARIAN M, Rouhi A. Gonial angle changes following mandibular set back using bilateral sagittal split ramus osteotomy (BSSRO). 2005.
11. Guglielmi M, Schneider KM, Iannetti G, Feng C, Martinez AY. Orthognathic Surgery for Correction of Patients With Mandibular Excess: Don’t Forget to Assess the Gonial Angle. Journal of Oral and Maxillofacial Surgery. 2013;71(6):1063-72.
12. Luo M, Yang X, Wang Q, Li C, Yin Y, Han X. Skeletal stability following bioresorbable versus titanium fixation in orthognathic surgery: a systematic review and meta-analysis. International Journal of Oral and Maxillofacial Surgery. 2018;47(2):141-51.
13. Chen Y, Zhang J, Rao N, Han Y, Ferraro N, August M. Independent risk factors for long-term skeletal relapse after mandibular advancement with bilateral sagittal split osteotomy. International Journal of Oral and Maxillofacial Surgery. 2020;49(6):779-86.
2. Hong J-S, Oh K-M, Kim B-R, Kim Y-J, Park Y-H. Three-dimensional analysis of pharyngeal airway volume in adults with anterior position of the mandible. American Journal of Orthodontics and Dentofacial Orthopedics. 2011;140(4):e161-e9.
3. In-Ho K, Chang-Hun H, Sun-Youl R. Changes in gonial angle and mandibular width after orthognathic surgery in mandibular prognathic patients. J Korean Assoc Oral Maxillofac Surg. 2006;32(2):129-37.
4. Tabrizi R, Pakshir H, Behnia H, Akhlaghi S, Shahsavari N. Does mandibular osteotomy affect gonial angle in patients with class III deformity? Vertical ramus osteotomy versus sagittal split osteotomy. International Journal of Oral and Maxillofacial Surgery. 2016;45(8):992-6.
5. Yazdani J, Talesh KT, Motamedi MH, Ghavimi MA. Changes in the gonial angle following bilateral sagittal split osteotomy and vertical ramus osteotomy for mandibular excess. Eplasty. 2010;10:e20.
6. Bayat M, Jafarian M, Habashi OG. Correlation between gonial angle and different variables after bilateral sagittal split ramus osteotomy. Journal of Dentistry of Tehran University of Medical Sciences. 2006;3(1):19-23.
7. Jönsson E, Svartz K, Welander U, Åstrand P. Mandibular rami osteotomies and their effect on the gonial angle. International journal of oral surgery. 1981;10(3):168-72.
8. Kang SH, Kim TJ, Shin HK. A CLINICAL STUDY OF CHANGES IN GONIAL ANGLE BETWEEN PRE-AND POST-ORTHOGNATHIC SURGERY IN MANDIBULAR PROGNATHIC PATIENTS. Journal of the Korean Association of Oral and Maxillofacial Surgeons. 1998;24(2):193-7.
9. Kwon YH, Jang HJ, Lee SH. CLINICAL ANALYSIS OF GONIAL ANGLE CHANGE AFTER ORTHOGNATHIC SUGERY IN PATIENTS WITH THE MANDIBULAR PROGNATHISM. Journal of Korean Association of Maxillofacial Plastic and Reconstructive Surgeons. 2000;22(2):206-16.
10. JAFARIAN M, Rouhi A. Gonial angle changes following mandibular set back using bilateral sagittal split ramus osteotomy (BSSRO). 2005.
11. Guglielmi M, Schneider KM, Iannetti G, Feng C, Martinez AY. Orthognathic Surgery for Correction of Patients With Mandibular Excess: Don’t Forget to Assess the Gonial Angle. Journal of Oral and Maxillofacial Surgery. 2013;71(6):1063-72.
12. Luo M, Yang X, Wang Q, Li C, Yin Y, Han X. Skeletal stability following bioresorbable versus titanium fixation in orthognathic surgery: a systematic review and meta-analysis. International Journal of Oral and Maxillofacial Surgery. 2018;47(2):141-51.
13. Chen Y, Zhang J, Rao N, Han Y, Ferraro N, August M. Independent risk factors for long-term skeletal relapse after mandibular advancement with bilateral sagittal split osteotomy. International Journal of Oral and Maxillofacial Surgery. 2020;49(6):779-86.
| Files | ||
| Issue | Vol 12, No 4 (Autumn 2025) | |
| Section | Original Article(s) | |
| Keywords | ||
| BSSO; Gonial angle; Occlusal plane angle; Bimaxillary osteotomy; Miniplate fixation. | ||
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How to Cite
1.
Mohammadi F, Safarian M. Changes in the Gonial Angle Following Bimaxillary Osteotomy. J Craniomaxillofac Res. 2026;12(4):241-245.
