Dental pathology in Pongo satyrus borneensis.

The Selenka orangutan collection obtained from 1892 to 1896 from wild-shot specimens in West Borneo, provides an excellent opportunity to examine dental pathology in free-ranging primates. Two hundred and twenty-three skulls from this collection were analyzed for dental conditions, including carious lesions, local infections (infra-alveolar and periapical osseous defects), horizontal bone loss, and premortem tooth loss. Specimens were sexed, divided into three broad age groups, and compared to ascertain sex-related or age-related differences in occurrence of dental pathology. None of the subadults displays any evidence of dental disease. One individual (2%) in the young adult group has a periapical osseous defect and evidence of horizontal bone loss, and another (2%) has two adjacent interproximal carious lesions. The old adults have a much higher prevalence of individuals afflicted with dental pathologies, including 6% carious lesions, 26% local infections, 23% horizontal bone loss, and 3% premortem tooth loss. The differences between the young and old adults in number of individuals afflicted with dental pathologies is statistically significant for local infections and horizontal bone loss. When compared by sex, the old adult group reveals that females have a higher occurrence of dental pathologies than males in all types of lesions recorded and these differences are statistically significant for local infections and horizontal bone loss. Considering the importance diet plays in the development of dental disease, it is suggested that ecological separation of the sexes, with the subsequent dietary differences, could be an important factor determining the higher prevalence of dental lesions observed in female orangutans. Additionally, the importance of local ecological factors, which may affect dietary patterns, are recognized as a potential source of variation in dental pathologies among different samples of orangutans.