Characterization of facial asymmetry phenotypes in adult patients with skeletal Class III malocclusion using three-dimensional computed tomography and cluster analysis
10.4041/kjod.2022.52.2.85
- Author:
Sang-Woon HA
1
;
Su-Jung KIM
;
Jin-Young CHOI
;
Seung-Hak BAEK
Author Information
1. Department of Orthodontics, School of Dentistry, Seoul National University, Seoul, Korea
- Publication Type:Original Article
- From:The Korean Journal of Orthodontics
2022;52(2):85-101
- CountryRepublic of Korea
- Language:English
-
Abstract:
Objective:To classify facial asymmetry (FA) phenotypes in adult patients with skeletal Class III (C-III) malocclusion.
Methods:A total of 120 C-III patients who underwent orthognathic surgery (OGS) and whose three-dimensional computed tomography images were taken one month prior to OGS were evaluated. Thirty hard tissue landmarks were identified. After measurement of 22 variables, including cant (°, mm), shift (mm), and yaw (°) of the maxilla, maxillary dentition (Max-dent), mandibular dentition, mandible, and mandibular border (Man-border) and differences in the frontal ramus angle (FRA, °) and ramus height (RH, mm), K-means cluster analysis was conducted using three variables (cant in the Max-dent [mm] and shift [mm] and yaw [°] in the Manborder). Statistical analyses were conducted to characterize the differences in the FA variables among the clusters.
Results:The FA phenotypes were classified into five types: 1) non-asymmetry type (35.8%); 2) maxillary-cant type (14.2%; severe cant of the Max-dent, mild shift of the Man-border); 3) mandibularshift and yaw type (16.7%; moderate shift and yaw of the Man-border, mild RH-difference); 4) complex type (9.2%; severe cant of the Max-dent, moderate cant, severe shift, and severe yaw of the Man-border, moderate differences in FRA and RH); and 5) maxillary reverse-cant type (24.2%; reverse-cant of the Max-dent). Strategic decompensation by pre-surgical orthodontic treatment and considerations for OGS planning were proposed according to the FA phenotypes.
Conclusions:This FA phenotype classification may be an effective tool for differential diagnosis and surgical planning for Class III patients with FA.
