Abstract
Tooth crown shapes differ among human groups because the sizes and shapes of the constituent crown components differ. It was of interest to us whether there is patterned variation in crown indexes between sexes or among ethnic groups. The crown index—buccolingual width as a function of mesiodistal length—was analyzed here in terms of sex and race differences in a cohort of American black and white adolescents (n = 324) from the U.S. Mid-South. The mandibular canine is distinctive in exhibiting significant sexual dimorphism in crown shape, with females being broader in terms of mesiodistal length. Prior literature reports the crown indexes of several tooth types to be dimorphic, which does not occur here, showing that the extent of sexual dimorphism differs among groups. In contrast, we found that multiple crown indexes differ significantly between the samples of blacks and whites, with the largest differences in UC, UP1, and LM2. Of note, nature of the differences are tooth-specific, suggesting that divergence among groups at this microevolutionary level has shifted crown shapes along distinctive (rather than parallel) pathways. The optimum subset of crown indexes correctly allocates 67% of the specimens as to race; this percentage is not much better than chance, suggesting that crown indexes are of little forensic usefulness in discriminating among contemporary humans.
Highlights
Tooth crown shapes differ among human groups because the sizes and shapes of the constituent crown components differ
Crowns of teeth vary both in size and shape, and this is well documented by dental anthropologists who have detailed the variations in the morphologies of all tooth types (e.g., Korenhof, 1960; Morris, 1965; Turner et al 1991; Scott, 2008)
The purpose of the present study is to explore the utility of using crown indexes of the permanent teeth to distinguish between males and females and, secondly, Correspondence to: Edward F
Summary
Tooth crown shapes differ among human groups because the sizes and shapes of the constituent crown components differ. Crowns of teeth vary both in size and shape, and this is well documented by dental anthropologists who have detailed the variations in the morphologies of all tooth types (e.g., Korenhof, 1960; Morris, 1965; Turner et al 1991; Scott, 2008). The purpose of the present study is to explore the utility of using crown indexes of the permanent teeth to distinguish between males and females and, secondly, CL FOSTER AND EF HARRIS to test for differences between American blacks and whites. These differences may suggest intra-specific (‘racial’) differences in modal crown development. The data may be of forensic use in estimating the race and/or sex of an unknown specimen (e.g., Ditch and Rose, 1972)
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