Patterns of dental wear in the Lengua Indians of Paraguay.

Wear patterns were examined on dental casts of 202 living Lengua Indians from the Chaco area of Paraguay. Consideration was given to the development of the molar helicoidal plane, age-related changes in occlusal attrition, coalescence of dentine exposures, interproximal attrition, and erupted crown height. This study lends support to Osborn's theory of the helicoidal plane development by showing that attrition enhances rather than modifies posteruption molar occlusal planes. The rate of interproximal attrition was found to slow down with the eruption and functional initiation of the third molars. Sinuous and cavo-convex interproximal contact areas that are generated with age, however, appeared to be less abrasion resistant than straight surfaces, hence leading to an increase in interproximal attrition rates with advanced age. Maximum crown height reduction occurred between the ages of 20 and 40 years in central incisors, canines, and first molars. Kruskal-Wallis tests and log linera models failed to demonstrate significant sexually dimorphic or antimeric differences in wear patterns of Lengua teeth.