Intercuspal distances of maxillary pre-molar teeth in Australian Aboriginals.

Intercuspal distances and mesiodistal and buccolingual crown diameters of maxillary pre-molars were recorded from dental casts of 262 Australian Aboriginals. Although mesiodistal and buccolingual dimensions showed sexual dimorphism, no significant differences were noted between the sexes for intercuspal distances. Intercuspal dimensions showed greater variability and fluctuating asymmetry than did either of the traditional measures. No significant differences in heritability were noted among the three dimensions. Correlations between mesiodistal and buccolingual dimensions were higher than those between buccolingual and intercuspal measures. It appears that the sex differences, which are observed in overall crown dimensions, are established after the cusp tips are localized. Intercuspal distances appear to have a strong genetic component of variability, although they show high phenotypic variability and fluctuating asymmetry. Total tooth size may be subject to more intense selective pressures than the sites of initial calcification.