目的: 探讨建立一种基于三维颜面软组织标志点的颏部对称性评价方法, 并对该方法的评价效果进行初步检验。方法: 使用标准对称人脸进行颏结节点坐标变换, 用以筛选软组织三维空间线角并构建相应的三维空间线角模板, 从2021年3月至2022年3月就诊于北京大学口腔医院正畸科的初诊患者中选取10例临床诊断存在颏部不对称的患者, 年龄12~32岁; 收集患者的三维软组织面部扫描数据, 通过MeshMonk非刚性配准算法程序自动确定测试患者面部扫描数据的标志点, 并以此生成三维软组织空间线角模板及相应参数。同时在Geomagic Studio 2015软件中进行人脸镜像重叠分析, 并生成颏部偏差色谱图作为检验参照, 对比三维软组织空间线角模板指标相对于重叠分析的识别率。结果: 通过坐标变换方式筛选三维空间线角指标9项, 在10例患者中对其面部扫描数据进行镜像重叠分析和三维空间线角模板分析, 以镜像重叠为"金标准", 计算用三维软组织空间线角模板分析法评价颏部不对称情况的识别率, 颏部不对称识别率为90%(9/10), 其中X维度识别率为86%, Y维度识别率为89%, Z维度识别率为100%。结论: 应用三维软组织线角模板法在评价颏部软组织不对称上有一定的可行性, 其在三维方向上具有分别识别不同维度不对称的能力, 优于镜像重叠方法, 但在识别率方面稍差, 仍需进一步改进和优化。

Objective: To develop an efficient and robust method based on three dimensional facial landmarks for evaluating chin region asymmetry at the soft tissue level and to compare it with the traditional mirror-overlap analysis method in order to test its availability. Methods: Standard symmetrical face was used for mental tubercle coordinate transformation so as to filter soft tissue three dimensional spatial angle and construct corresponding three dimensional spatial angle wireframe template. Ten patients aged 12-32 years with clinical chin region asymmetry diagnosis at the Department of Orthodontics of Peking University Hospital of Stomatology from November 2020 to November 2021 were randomly selected. Three dimensional soft tissue face scan data of the patients were collected by three dimensional face scanner and the landmark points were automatically determined by the Meshmonk non-rigid registration algorithm program, and in this way, the asymmetric three dimensional spatial angle wireframe template and corresponding spatial angle parameters were generated. Mirror-overlap analysis of face scan data was also performed in Geomagic Studio 2015 software and deviation color maps were generated. This study took mirror-overlap analysis as the gold standard method, the response rate of chin region asymmetry was eva-luated by the outcomes of the mirror-overlap analysis and three dimensional spatial angle wireframe template analysis. Results: Nine three dimensional spatial angle indicators were selected through coordinate transformation, and the response rate was calculated using mirror-overlap analysis as the gold standard method. Among these ten selected patients, the response rate of the total chin region asymmetry was 90% (9/10). Using the deviation value of mirror-overlap analysis as a reference, the response rate of chin region asymmetry in the X dimension was 86%, the response rate of chin region asymmetry in the Y dimension was 89%, and the response rate of chin region asymmetry in the Z dimension was 100%. Conclusion: The three dimensional soft tissue spatial angle wireframe template proposed in this study has some feasibility in evaluating chin region asymmetry at the soft tissue level, and its ability to recognize asymmetry separately in the three dimensional direction is better than the mirror-overlap analysis method, and the indicators recognition rate still needs to be further improved.