Single stage surgery for contouring the prominent mandibular angle with a broad chin deformity: en-bloc Mandibular Angle-Body-Chin Curved Ostectomy (MABCCO) and Outer Cortex Grinding (OCG).

BACKGROUND: Various surgical options are reported to address the Asian 'squared face', characterized by a prominent mandibular angle (PMA) associated with an oversized chin deformity; but shortcomings lie in the requirement of multi-stage procedures with the risk of further revision surgery. We have developed a single-stage "Mandibular Angle-Body-Chin Curved Ostectomy (MABCCO) and Outer Cortex Grinding (OCG)" surgical technique to shorten the period of the surgical treatment and minimize the inherent surgical risks in the multi-staged procedures.

METHODS: A retrospective study involving patients (n = 36) presented with prominent mandibular angle and an oversized chin who underwent the operation described from 2010 to 2012 with at least 12 months of follow-up. The surgical and aesthetic outcomes were evaluated through clinical assessment, photography, imaging analysis including preoperative and post-operative patient satisfaction rates.

RESULTS: All the patients were satisfied with the improvement in their appearance following surgery; specifically the 'smoothness' of the mandibular inferior border with no 'second mandibular angle'. The width of the mandible was reduced with G-G distance reduced from 119.9 mm ± 3.9-109.7 mm ± 3.5 (p < 0.05). A significant preoperative and post-operative gonial angle (G-A) was found at the left (110.7° ± 9.6 vs 139.9° ± 11.5, p < 0.05) and right side of mandible (111.3° ± 10.7 vs 140.7° ± 11.8, p < 0.05). There was no iatrogenic inferior alveolar nerve or mental nerve injury and a stable aesthetic outcome beyond the first year.

CONCLUSION: We demonstrated favourable surgical and aesthetic outcomes with our single-stage en-bloc curved osteotomy surgical technique to reshape the prominent mandibular angle with a broad chin deformity with no increased in surgical risks but a high satisfaction rate and stable outcomes.