Comparison of Bilateral Mandibular Angle Ostectomy Between East Asian Males and Females: A Study Based on Three-Dimensional Computed Tomography Reconstruction.

[BACKGROUND] Mandibular angle ostectomy is a common plastic surgery for facial contouring in East Asians. However, rarely we could find reports on differences between East Asian males and females undergoing this surgery.

[OBJECTIVE] To describe the differences between East Asian males and females before and after mandibular angle ostectomy.

[METHODS] A total of 22 Asian males and 52 Asian females who underwent mandibular angle ostectomy from April 2015 to November 2018 were enrolled. Three-dimensional computed tomography was used to evaluate the preoperative and postoperative data of the mandible. Thirteen clinical data were measured on reconstructed mandibular models. The differences in data between males and females were analyzed to identify the causes of the differences before and after surgery. The follow-up was 6-12 months, and patient satisfaction was also evaluated.

[RESULTS] The ostectomy volume was positively correlated with the distance from the intersection of the occlusal plane and the anterior margin of the mandibular ramus to gonion (MR-Go; female, p < 0.01; male, p = 0.02). There was a positive correlation between the ostectomy volume and the postoperative drainage fluid (The drainage fluid is mainly blood) volume after surgery in females (p < 0.05), while there is no significant correlation between these two data in males (p = 0.19). Patients with a long distance from the second molar to the lower edge of the mandibular body (SM-MB) tended to have a higher risk of postoperative bleeding (female, r = 0.56, p < 0.01; male, r = 0.73, p = 0.01).

[CONCLUSION] Because of the difference in the anatomical size of the mandible and different aesthetic requirements for facial contouring between males and females, surgeons encounter different intraoperative conditions resulting in difficulties during surgery. Understanding differences in mandibular angles predicts differences in ostectomy volume and postoperative bleeding risk, thus aiding surgeons and leading to better operative outcomes.

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