Longitudinal radiographical study on the rate of alveolar bone loss in patients of a dental school.

Two sets of radiographs, taken at an interval of 4-14 years in 105 patients of a dental school, were examined in order to determine the rate of resorption of alveolar bone. The percentage loss of maximum alveolar bone height was measured in the interproximal and interradicular sites by means of the Schei ruler. The average percentage of interproximal bone resorption was 0.51% (0.07 mm) per year. Age, sex, professional status, type of periodontal treatment and general state of health did not seem to affect the annual resorption rate. However, crowned teeth had a significantly greater rate of resorption than uncrowned teeth. Loss of bone tended to be more rapid in interdental as compared to interradicular areas. A positive and statistically significant correlation was found between initial resorption and annual tooth loss.