Approximal grooving of teeth

Approximal grooving of teeth is a form of tooth wear seen in some fossil hominids (Neandertal Man and Pekin Man) and in some primitive peoples (Bushmen, Australian aborigines and American Indians). Previous workers have claimed the grooves were produced either by an acid secreted from the gum or by constant probings with a tooth‐pick. The purpose of this paper is to refute these hypotheses, and to suggest from observations on the morphology of the grooves in four Bushman skulls, one American Indian skull, and one South African Negro skull that the approximal grooves are produced by dietary grit (sand and soil in the food and drinking water) being sucked from the vestibule into the oral cavity proper during the mouth‐cleansing phase of swallowing.