College of Forensic Medicine, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China.
Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, College of Stomatology, Xi'an Jiaotong University, 98 XiWu Road, Xi'an, 710004, Shaanxi, People's Republic of China.
Int J Legal Med. 2019 Nov;133(6):1925-1933. doi: 10.1007/s00414-019-02112-2. Epub 2019 Jul 4.
The present study aims to evaluate the relation between chronological age and the ratio of pulp volume (PV) to enamel volume (EV) of impacted mandibular third molars (IMTMs) by using cone-beam computed tomography (CBCT) images and an improved 3D image segmentation technique. A sample of CBCT images of IMTM was collected from 414 northern Chinese subjects (214 male and 200 female clinical patients) ranging in age from 20 to 65 years. The GrowCut effect image segmentation (GCEIS) module algorithm was used to calculate the PV and EV from CBCT images. The total sample was divided into a training group and validation group in a ratio of 7 to 3. The PV/EV ratio (PEr) in the training sample was used to develop a mathematical formula for age estimation as follows: age = - 5.817-21.726 × Ln PEr (p < 0.0001) (Ln, natural logarithm). The mean absolute error (MAE) and root mean square error (RMSE) were used to determine the precision and accuracy of the mathematical formula in the validation group and all samples. The MAEs in the male, female, and pooled gender samples were 9.223, 7.722, and 8.41, respectively, and the RMSEs in the male, female, and pooled gender samples were 10.76, 9.58, and 9.986, respectively. The precise and accurate results indicate that the PEr of IMTM in CBCT images is a potential index for dental age estimation and is possible to be used in forensic medicine.
本研究旨在通过锥形束 CT（CBCT）图像和改进的 3D 图像分割技术，评估下颌阻生第三磨牙（IMTM）的冠根比（PV/ EV）与年龄的关系。从 414 名中国北方（214 名男性和 200 名女性）年龄在 20 至 65 岁的临床患者的 IMTM 的 CBCT 图像中采集样本。使用 GrowCut 效应图像分割（GCEIS）模块算法从 CBCT 图像中计算 PV 和 EV。将总样本按 7:3 的比例分为训练组和验证组。在训练样本中，PV/EV 比值（PEr）用于开发如下的年龄估计数学公式：年龄=-5.817-21.726×Ln PEr（p<0.0001）（Ln，自然对数）。使用平均绝对误差（MAE）和均方根误差（RMSE）来确定数学公式在验证组和所有样本中的精度和准确性。男性、女性和混合性别样本的 MAE 分别为 9.223、7.722 和 8.41，男性、女性和混合性别样本的 RMSE 分别为 10.76、9.58 和 9.986。精确且准确的结果表明，CBCT 图像中 IMTM 的 PEr 是牙龄估计的潜在指标，有可能应用于法医学。
