Cao Hua-Lian, Kang Moon-Ho, Lee Jin-Yong, Park Won-Jong, Choung Han-Wool, Choung Pill-Hoon
Department of Oral and Maxillofacial Surgery, Dental Research Institute, School of Dentistry, Seoul National University, 101 Daehak-ro, Jongro-gu, Seoul, 03080 South Korea.
Onsam Dental Clinic, Seoul, South Korea.
Maxillofac Plast Reconstr Surg. 2020 May 25;42(1):17. doi: 10.1186/s40902-020-00260-9. eCollection 2020 Dec.
To evaluate the facial asymmetry, three-dimensional computed tomography (3D-CT) has been used widely. This study proposed a method to quantify facial asymmetry based on 3D-CT.
The normal standard group consisted of twenty-five male subjects who had a balanced face and normal occlusion. Five anatomical landmarks were selected as reference points and ten anatomical landmarks were selected as measurement points to evaluate facial asymmetry. The formula of facial asymmetry index was designed by using the distances between the landmarks. The index value on a specific landmark indicated zero when the landmarks were located on the three-dimensional symmetric position. As the asymmetry of landmarks increased, the value of facial asymmetry index increased. For ten anatomical landmarks, the mean value of facial asymmetry index on each landmark was obtained in the normal standard group. Facial asymmetry index was applied to the patients who had undergone orthognathic surgery. Preoperative facial asymmetry and postoperative improvement were evaluated.
The reference facial asymmetry index on each landmark in the normal standard group was from 1.77 to 3.38. A polygonal chart was drawn to visualize the degree of asymmetry. In three patients who had undergone orthognathic surgery, it was checked that the method of facial asymmetry index showed the preoperative facial asymmetry and the postoperative improvement well.
The current new facial asymmetry index could efficiently quantify the degree of facial asymmetry from 3D-CT. This method could be used as an evaluation standard for facial asymmetry analysis.
为了评估面部不对称性，三维计算机断层扫描（3D - CT）已被广泛应用。本研究提出了一种基于3D - CT量化面部不对称性的方法。
正常标准组由25名面部匀称且咬合正常的男性受试者组成。选择5个解剖标志点作为参考点，10个解剖标志点作为测量点来评估面部不对称性。利用标志点之间的距离设计面部不对称指数公式。当标志点位于三维对称位置时，特定标志点的指数值为零。随着标志点不对称性增加，面部不对称指数值增大。对于10个解剖标志点，在正常标准组中获得每个标志点的面部不对称指数平均值。将面部不对称指数应用于接受正颌手术的患者。评估术前面部不对称性及术后改善情况。
正常标准组中每个标志点的参考面部不对称指数为1.77至3.38。绘制了多边形图表以直观显示不对称程度。在3例接受正颌手术的患者中，经检查面部不对称指数方法能很好地显示术前面部不对称性及术后改善情况。
当前新的面部不对称指数能够有效地从3D - CT量化面部不对称程度。该方法可作为面部不对称分析的评估标准。
