Yong Robin, Ranjitkar Sarbin, Lekkas Dimitra, Halazonetis Demetrios, Evans Alistair, Brook Alan, Townsend Grant
Adelaide Dental School, University of Adelaide, Adelaide, South Australia 5005, Australia.
School of Dentistry, National and Kapodistrian University of Athens, Athens 11527, Greece.
Am J Phys Anthropol. 2018 Jun;166(2):373-385. doi: 10.1002/ajpa.23438. Epub 2018 Feb 15.
This study aimed to investigate size and shape variation of human premolars between Indigenous Australians and Australians of European ancestry, and to assess whether sex and ancestry could be differentiated between these groups using 3D geometric morphometrics.
Seventy dental casts from each group, equally subdivided by sex, were scanned using a structured-light scanner. The 3D meshes of upper and lower premolars were processed using geometric morphometric methods. Seventy-two landmarks were recorded for upper premolars and 50 landmarks for lower premolars. For each tooth type, two-way ANOVA was used to assess group differences in centroid size. Shape variations were explored using principal component analysis and visualized using 3D morphing. Two-way Procrustes ANOVA was applied to test group differences for ancestry and sex, and a "leave-one-out" discriminant function was applied to assess group assignment.
Centroid size and shape did not display significant difference between the sexes. Centroid size was larger in Indigenous Australians for upper premolars and lower second premolars compared to the Australians of European ancestry. Significant shape variation was noted between the two ancestral groups for upper premolars and the lower first premolar. Correct group assignment of individual teeth to their ancestral groups ranged between 80.0 and 92.8% for upper premolars and 60.0 and 75.7% for lower premolars.
Our findings provide evidence of significant size and shape variation in human premolars between the two ancestral groups. High classification rates based on shape analysis of upper premolars highlight potential application of geometric morphometrics in anthropological, bioarcheological and forensic contexts.
本研究旨在调查澳大利亚原住民和欧洲裔澳大利亚人之间前磨牙的大小和形状差异，并评估是否可以使用三维几何形态测量学在这些群体之间区分性别和血统。
使用结构光扫描仪对每组70个牙模进行扫描，每组按性别平均细分。上下颌前磨牙的三维网格使用几何形态测量方法进行处理。上颌前磨牙记录72个地标点，下颌前磨牙记录50个地标点。对于每种牙齿类型，使用双向方差分析评估质心大小的组间差异。使用主成分分析探索形状变化，并使用三维变形进行可视化。应用双向普氏方差分析测试血统和性别的组间差异，并应用“留一法”判别函数评估组分配情况。
质心大小和形状在性别之间没有显示出显著差异。与欧洲裔澳大利亚人相比，澳大利亚原住民的上颌前磨牙和下颌第二前磨牙的质心大小更大。在两个血统组之间，上颌前磨牙和下颌第一前磨牙存在显著的形状差异。上颌前磨牙将个体牙齿正确分配到其血统组的比例在80.0%至92.8%之间，下颌前磨牙在60.0%至75.7%之间。
我们的研究结果提供了证据，表明两个血统组之间人类前磨牙存在显著的大小和形状差异。基于上颌前磨牙形状分析的高分类率突出了几何形态测量学在人类学、生物考古学和法医学背景下的潜在应用。
