OBJECTIVE: To assess reliability of cone-beam CT (CBCT) for nasolabial soft tissue measurements in patients with skeletal class III malocclusion based on 3-dimensional (3D) facial scanner results. METHODS:CBCT and 3D facial scan images of 20 orthognathic patients are used in this study. Eleven softtissue landmarks and 15 linear and angular measurements are identified and performed. For qualitative evaluation, Shapiro-Wilk test and Bland-Altman plots are applied to analyze the equivalence of the measurements derived from these two kinds of images. To quantify specific deviation of CBCT measurements from facial scanner, the latter is set as a benchmark, and mean absolute difference (MAD) and relative error magnitude (REM) for each variable are also calculated. RESULTS:Statistically significant differences are observed in regions of nasal base and lower lip vermilion between two methods. MAD value for all length measurements are less than 2 mm and for angular variables < 8°. The average MAD and REM for length measurements are 0.94 mm and 5.64%, and for angular measurements are 2.27° and 3.78%, respectively. CONCLUSIONS:The soft tissue results measured by CBCT show relatively good reliability and can be used for 3D measurement of soft tissue in the nasolabial region clinically.

中文翻译：

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锥形束CT对骨骼III类错牙合患者鼻唇软组织形态测量的可靠性：定性和定量分析

目的：基于 3 维 (3D) 面部扫描结果评估锥形束 CT (CBCT) 对骨骼 III 类错牙合患者鼻唇软组织测量的可靠性。方法：本研究使用20例正颌患者的CBCT和3D面部扫描图像。识别并执行 11 个软组织标志和 15 个线性和角度测量。对于定性评估，Shapiro-Wilk 检验和 Bland-Altman 图用于分析从这两种图像得出的测量值的等效性。为了量化面部扫描仪的 CBCT 测量值的特定偏差，将后者设置为基准，并计算每个变量的平均绝对差 (MAD) 和相对误差幅度 (REM)。结果：两种方法在鼻基底和下唇朱红色区域观察到统计学上的显着差异。所有长度测量的 MAD 值均小于 2 mm，角度变量 < 8°。长度测量的平均 MAD 和 REM 分别为 0.94 mm 和 5.64%，角度测量的平均 MAD 和 REM 分别为 2.27° 和 3.78%。结论:CBCT测量的软组织结果具有较好的信度,可用于临床上鼻唇区软组织的3D测量。