Tooth transposition prevalence and type among sub-Saharan Africans.

Abstract

Although rare, tooth transposition-an exchange in location of two teeth-is a frequent topic of study. Clinical and, to a much lesser extent, dental anthropological research have focused predominantly on prevalence (0.03%-0.74% in several world populations) and case studies, albeit on a restricted spatiotemporal scale. Many regions have received little attention, including sub-Saharan Africa, while premodern data are few. Here, the aim is to supplement both fields of dental research by reviewing previous publications, and newly reporting transposition rates, types, and co-occurring abnormalities in time-successive samples across the subcontinent. Dental data in 51 sub-Saharan samples (>2500 individuals) dating >10 000 BC to 20th century were recorded. Of these, 36 are of modern and 15 premodern age, comprising males and females ≥12-years of age. Transposition presence, quadrant, and type were tabulated, cases described, and prevalence presented. In the latter case, Poisson 95% confidence intervals were calculated to better discern true population rates at various geographic levels. Overall, six of 1886 modern individuals (0.32%) and one of premodern age evidence Mx.C.P1, an exchange of the maxillary canine and first premolar. Various associated dental abnormalities are also evident, including retained deciduous teeth, reduced permanent crowns, and agenesis. This study provides additional insight into the geographic distribution, features, and time depth of transposition, along with hints supporting a genetic etiology and, potentially, some indications of diachronic change from an initial Mx.C.P1 to several types more recently based on premodern evidence. It is of clinical concern today, but is not just a modern anomaly.