Diversity of Dental Observable Characteristics among Contemporary Chinese Groups

Abstract

This study is based on 3D dental models of contemporary Chinese groups and dental landmarking methods used according to research protocols developed by the Consortium for the Analysis of the Diversity and Evolution of Latin America (CANDELA). Dental phenotypes represented by Euclidean linear distances (ELD) computed between landmarks are used to assess dental diversity. This study aims to explore the impact of individual factors (age and gender) and population factors (ethnic groups) on dental diversity among contemporary Chinese groups. The results of canonical variate analysis (CVA), cross-validated canonical variate analysis (CV), principal component analysis (PCA), Pearson correlation analyses, and biodistances showed that the dental observable characteristics of populations that had closer evolutionary relationships were often more similar. Specifically, the dental observable characteristics of the upper teeth of Han nationality are closer to those of Zhuang and Miao nationalities but different from those of Mongolian nationality, and the dental observable characteristics of upper and lower teeth of Tibetan nationality are different from those of Uyghur nationality. The biodistance differentiation in dental phenotypes of southern/ northern/ central Han Chinese was clearly directional (clines), and the differences in mandibular teeth were higher than those of maxillary teeth. From the perspective of gender, the differences in dental phenotypes between men and women were mainly reflected in the canines, and the average width and height of male canines were significantly greater than that of female canines. The analysis among different age groups showed that the influence of extragenetic factors on the dental observable characteristics was mainly reflected in the canines, maxillary first molars, and mandibular first premolars.

本研究基于当代中国人群 3D 牙齿模型数据, 参照拉美人群进化和多样性研究联合会( consortium for the analysis of the diversity and evolution of Latin America, CANDELA)所使用的牙齿特征点标记方法, 使用牙齿特征点间的欧几里得线性距 离(Euclidean linear distances, ELD)表示的牙齿表型作为牙齿可观测特征的度量, 探究个体因素(年龄、 性别)和群体因素(民 族)对当代中国人群牙齿可观测特征多样性的影响。 通过对牙齿标记特征点的典型变量分析( canonical variate analysis, CVA)、 交叉验证(cross validation, CV)、 主成分分析(principal component analysis, PCA)以及对牙齿表型的 Pearson 相关性分 析和差异分析, 本研究发现进化上相近的群体牙齿可观测特征往往更接近。 具体来说, 汉族的上颌牙齿可观测特征和壮族、 苗族较为接近而不同于蒙古族的, 而藏族的上、 下颌牙齿可观测特征不同于维吾尔族的; 南北中汉族牙齿表型的差异具有明 确的方向性, 下颌牙齿差异比上颌更明显; 从性别角度看, 男女牙齿表型差异主要体现在尖牙上, 男性尖牙平均宽度和高度 显著大于女性的; 对不同年龄群体的差异分析表明, 遗传外因素对牙齿可观测特征的影响主要体现在尖牙、 上颌第一磨牙、 下颌第一前磨牙上。