Relationship between size of distal accessory tubercles and hypocones in permanent maxillary molar crowns of southern Africans.

The relationships between total occlusal crown area and the basal cusp areas of the accessory distal tubercle (C5) and the hypocone were analysed in molars of complete upper tooth rows of a southern African sample. While non-parametric tests between hypocone and C5 sizes did not yield statistically significant results, analyses of metrical data revealed a trend towards compensatory interaction between both cusps. Contrary to previous reports the size of C5 was found to be independent of total crown area. As enamel is thickest on cusp tips there may be a functional reason for the frequency of occurrence of the distal accessory tubercle. The pattern of distribution of the hypocone and C5 within a tooth row may be related to the occlusal wear pattern in Homo, which exhibits a marked lingual slope of wear in anterior molars and a horizontal or even buccal slope in posterior teeth.