Buccal alveolar exostoses: Prevalence, characteristics, and evidence for buttressing bone formation

Background: Buttressing bone formation has been described as the development of thickened or exostotic buccal alveolar bone in response to heavy occlusal forces. Little supporting evidence for this model has been found in previous literature, however and there is little seen on the prevalence or characteristics of buccal alveolar exostoses. Methods: A sample of 416 selected teeth and investing bone in 52 modern skeletal specimens at the National Museum of Natural History were examined. Two measures of heavy occlusal function-periodontal ligament (PDL) width and occlusal attrition-were analyzed for their relationship to three parameters of buccal alveolar bone (exostoses, lipping, and overall thickness). Results: Buccal alveolar bone enlargements were found in 25% of all teeth examined: 18% were expressed as marginal bony lippings and 7% as buccal exostoses. Exostoses were mainly seen around maxillary molars and bicuspids, especially in males, while lippings were seen in molars, bicuspids, and mandibular incisors, with even gender distribution. When findings were controlled for arch and tooth type, no significant correlations were found between wider PDL spaces or occlusal attrition and exostotic, lipped, or thicker alveolar bone. Conclusions: These results indicate a lack of anatomic evidence for the theory of buttressing bone formation and suggest that other factors may be of greater importance in the etiology of buccal bone enlargements. Incidentally, no correlation was found between widened PDL spaces or severe occlusal attrition and the presence of cervical loss of tooth structure, which casts doubt on the currently popular concept of abfraction.