Evidence for a secular trend in the Negro dentition.

Metric changes in the Negro dentition were evaluated in a sample of artificial stone casts of the dental arcades of 106 living South African Negroes (56 males, 50 females) and in 100 Negro crania (50 males, 50 females) drawn from the R. A. Dart Collection. Comparison of the mesiodistal and buccolingual dimensions of these two samples to the published results of a similar study on earlier Negroes revealed a statistically significant trend towards tooth-size enlargement. This positive secular trend was found to be most pronounced in the mesiodistal diameter, with less than half of the teeth considered showing significant buccolingual enlargement. Although the trend was equally pronounced in both sexes and in both arcades, mesiodistal change was found to increase in an antero-posterior direction, while buccolingual change centred around the anterior teeth.