A Novel and Simplified Parameter for Mandible Angle Asymmetry Evaluation in Chinese Females.

[AIM] To develop a novel and simplified parameter for mandible angle asymmetry (MAA) evaluation for facial countering surgeries in Chinese females.

[MATERIALS AND METHODS] A total of 250 craniofacial computer tomography of healthy Chinese individuals were collected in this retrospective study. Mimics 21.0 was applied for 3-dimensional anthropometry. The Frankfort and Green planes were set as referenced vertical and horizontal planes for measuring the distances to gonions. The differences in both orientations were analyzed to verify the symmetry. Mandible angle asymmetry (∠Go-N-ANS, MAA) which comprehensively represented horizontal and vertical placements was defined qas the novel parameter for asymmetric evaluation and quantitative analysis was conducted to generate referenced materials.

[RESULTS] Mandible angle asymmetry was divided into horizontal and vertical asymmetry. No significant differences were found in either horizontal or vertical orientations. The horizontal difference was 3.09±2.52 mm, the reference range was (0.28, 7.54) mm, whereas the±ertical difference was 2.59±2.48 mm, the reference range was (0.12, 6.34) mm. The difference of MAA was 1.74±1.30 degrees, and the reference range was (0.10,4.32）degrees.

[CONCLUSION] This study provided a novel parameter for asymmetric evaluation in the mandible angle region through quantitative 3-dimensional anthropometry, arousing plastic surgeons' attention to both aesthetics and symmetry in facial contouring surgery.