The prevalence and features of 3 types of exostoses commonly encountered during periodontal surgery were studied in a sample of 328 modern American skulls drawn from the collection at the American Museum of Natural History. Measurements were made of the height, width, and breadth of exostoses. The relationship to teeth or other skeletal structures was also recorded. Palatal tubercles were observed in 56% of all skulls (69% of all dentate skulls), with higher prevalences among males and African-Americans. Palatal tubercles were commonly associated with second and third molars, and were usually directly lateral to and a mean of 11.4 mm from the greater palatine foramen. Mandibular tori were observed in 27% of all skulls (42% of dentate skulls), with higher prevalences seen among African-Americans and males. The importance of these findings relates to the frequent need for exostosis removal to permit proper flap adaptation, especially in the posterior maxilla, and to the potential use of the mandibular and palatal tori as sources of autogenous cortical bone.

This paper describes 4 cases of spontaneous exposure and sequestration of alveolar bone. While one case was associated with an allergic mucositis, the other three were idiopathic involving large lingual exostoses.