Comparison of incidence of torus mandibularis and average number of present teeth among 2010 consecutive dental patients over 10 yr of age revealed that these variables seemed to be positively related: patients with torus mandibularis had on the average more teeth present than those without torus (P less than 0.0000001). The difference was statistically significant in all age classes except 50 years and over. In the adolescent age class, 10-19-yr, patients with torus mandibularis had on the average fewer unerupted canines than those without torus indicating that the hyperostosis seemed to be associated with more adequately developed jaws. The decreasing incidence of torus mandibularis with age approximately paralleled the decreasing number of present teeth, indicating that number of functioning teeth seems to be a factor of importance for the maintenance of the trait.