Vossoughi Mehrdad, Movahhedian Najmeh, Ghafoori Alireza
Oral and Dental Disease Research Center, Department of Dental Public Health, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.
Department of Oral and Maxillofacial Radiology, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.
Int J Legal Med. 2022 Jan;136(1):269-278. doi: 10.1007/s00414-021-02651-7. Epub 2021 Jul 21.
Methods based on pulp/tooth ratios proposed by Kvaal et al. (1995) have been widely used for age estimation in adults. The tendency of age estimates to mimic the age structure of the reference population, i.e. age mimicry bias, is a possible source of controversy in the results of studies. The primary objective of the present study was to evaluate the effect of age mimicry bias on the accuracy of the original Kvaal's method and its recent modification proposed by Roh et al. (2018).
The study sample comprised 240 cone-beam computed tomography scans of an Iranian population. The bootstrap procedure was used to study the impact of age mimicry bias on age estimates by constructing reference populations with different age structures. The accuracy of Kvaal's and Roh's variables for age estimation was assessed using a twofold cross-validation technique and principal component analysis.
The application of original equations resulted in SEE values highly greater than the acceptable threshold for forensic purposes (10 years). The population-specific equations obtained SEE values of 9.18, 11.03, and 9.22 years using Kvaal's variables and 9.19, 11.13, and 9.14 years using Roh's variable for the maxillary, mandibular, and all teeth, respectively. The bootstrap procedure revealed that using uneven reference populations to formulate the equation resulted in significantly greater SEEs (almost all >10 years) that were not acceptable for forensic purposes. Moreover, using an older (a younger) reference population contributed to a sharp rise in the amount of over- (under-) estimation for younger (older) age groups.
Age mimicry bias had an undesirable impact on the accuracy of dental age estimation based on Kvaal's and Roh's methods. The accuracy of the original equations was low for age estimation in the Iranian sample. However, the performance of the population-specific equations was reasonably acceptable for the maxillary and all six teeth.
基于Kvaal等人（1995年）提出的牙髓/牙齿比例的方法已广泛用于成年人的年龄估计。年龄估计倾向于模仿参考人群的年龄结构，即年龄模仿偏差，这可能是研究结果中争议的一个来源。本研究的主要目的是评估年龄模仿偏差对原始Kvaal方法及其最近由Roh等人（2018年）提出的修改方法准确性的影响。
研究样本包括240例伊朗人群的锥形束计算机断层扫描。通过构建具有不同年龄结构的参考人群，采用自助法研究年龄模仿偏差对年龄估计的影响。使用双重交叉验证技术和主成分分析评估Kvaal和Roh年龄估计变量的准确性。
应用原始方程得出的标准误（SEE）值远高于法医目的可接受阈值（10年）。使用Kvaal变量，上颌、下颌和所有牙齿的特定人群方程得出的SEE值分别为9.18年、11.03年和9.22年；使用Roh变量，相应的SEE值分别为9.19年、11.13年和9.14年。自助法表明，使用不均衡的参考人群来制定方程会导致明显更高的SEE（几乎所有均>10年），这对于法医目的是不可接受的。此外，使用年龄较大（较小）的参考人群会导致较年轻（较年长）年龄组的高估（低估）量急剧增加。
年龄模仿偏差对基于Kvaal和Roh方法的牙齿年龄估计准确性产生了不良影响。原始方程在伊朗样本中的年龄估计准确性较低。然而，特定人群方程在上颌和所有六颗牙齿方面的表现合理可接受。
