The University of Western Australia Dental School, The University of Western Australia, Nedlands, Western Australia, Australia.
The University of Western Australia Dental School, The University of Western Australia, Nedlands, Western Australia, Australia.
Am J Orthod Dentofacial Orthop. 2020 Jul;158(1):134-146. doi: 10.1016/j.ajodo.2019.12.014. Epub 2020 May 12.
It is considered normal for facial structures to exhibit mild asymmetry between left and right sides. An automated, landmark-independent method was developed to accurately assess and quantify facial asymmetry in 3 planes of space and describe a midline deviation of each subject and ultimately establish thresholds of significance.
The subjects were 279 healthy young Western Australian white adults (134 females and 145 males) with a mean age 22.17 years ± 0.63, (minimum 20.58 years-maximum 24.42 years) without craniofacial anomalies. They were randomly selected from participants in the Raine Study-Generation 2. Surface facial images were obtained using a 3dMDface scanning system (3dMD Inc, Atlanta, Ga). Images were standardized using the dense correspondence technique. An automated landmark detection method was applied, and measurements performed on color deviation maps to quantitatively assess facial asymmetry.
Based on asymmetrical projections over the total facial surface area, the proportion of female and males with moderate asymmetry (2-5 mm) was 52.3% and 58.4%, respectively, and with severe asymmetry (>5 mm) was 7.1% and 7.7%, respectively. Most asymmetry occurred in the coronal plane (x-axis), followed by the transverse plane (z-axis) and the least asymmetry in the sagittal plane (y-axis). Males were statistically more asymmetrical (P <0.05) in the coronal and transverse planes (males: coronal 36.5%, transverse 15.2%; females: coronal 31.8%, transverse 12.3%). The midline was deviated to the right in all females and in all but 1 male subject.
This study presents an automated, rapid and accurate method of assessing 3-dimensional facial asymmetry (using symmetry and midline analyses). Analyses revealed that >50% of the faces of young adults are >2 mm asymmetrical, based on total facial surface area.
左右两侧的面部结构存在轻微不对称被认为是正常的。我们开发了一种自动化的、不依赖于标志的方法，以在 3 个空间平面上准确评估和量化面部不对称，并描述每个受试者的中线偏差，最终建立显著差异的阈值。
研究对象为 279 名健康的年轻西澳大利亚白人成年人（女性 134 名，男性 145 名），平均年龄 22.17±0.63 岁（最小年龄 20.58 岁，最大年龄 24.42 岁），无颅面畸形。他们是从 Raine 研究-第 2 代的参与者中随机选择的。使用 3dMDface 扫描系统（3dMD Inc，亚特兰大，佐治亚州）获得面部表面图像。使用密集对应技术对图像进行标准化。应用自动化的标志点检测方法，通过彩色偏差图进行测量，以定量评估面部不对称。
基于整个面部表面积的不对称投影，女性和男性中度不对称（2-5 毫米）的比例分别为 52.3%和 58.4%，严重不对称（>5 毫米）的比例分别为 7.1%和 7.7%。大多数不对称发生在冠状面（x 轴），其次是横切面（z 轴），矢状面（y 轴）的不对称最少。男性在冠状面和横切面上的不对称程度明显更高（P<0.05）（男性：冠状面 36.5%，横切面 15.2%；女性：冠状面 31.8%，横切面 12.3%）。所有女性和除 1 名男性外，所有男性的中线都偏向右侧。
本研究提出了一种自动化、快速、准确的评估 3 维面部不对称的方法（使用对称和中线分析）。分析表明，基于整个面部表面积，超过 50%的年轻成年人的面部存在>2 毫米的不对称。
