THE ANGULAR BONY DEFECT AS INDICATOR OF FURTHER ALVEOLAR BONE LOSS

The aim of the present retrospective study was to evaluate alterations of the alveolar bone level over a 10-year period at tooth sites with "angular" and "even" patterns of bone loss, in subjects who were not exposed to systematic periodontal therapy. A further objective was to evaluate whether the presence of an angular defect can serve as a predictor of additional bone loss. 201 subjects in ages 25-70 years were examined radiographically on 2 occasions 10 years apart. 194 were dentate on the 2nd examination. The radiographic bone height at the mesial and distal aspect of all teeth was assessed by measuring the distance between the cemento-enamel junction and the bone crest. The morphologic pattern of alveolar bone loss at baseline was assessed for each tooth site. Angular defects were classified as degree 1, 2 and 3, according to increasing defect depth. The change in periodontal bone height over the 10-year period was calculated for each site. The results demonstrated an increased frequency of tooth loss among teeth showing presence of an angular bony defect at baseline; whereas 13% of the teeth with an even pattern of bone loss were lost between the 2 examinations, this proportion was 22%, 46% and 68% for teeth with an angular defect of degree 1, degree 2 and degree 3, respectively. Longitudinal bone loss of greater-than-or-equal-to 2 mm occurred more often among sites showing an angular defect when compared to sites with an even alveolar bone morphology. Multiple regression analysis revealed a statistically significant increased longitudinal bone loss for tooth sites with angular defects, even though the individual subject's overall past experience of alveolar bone loss and the particular tooth site initial degree of bone loss were taken into account. With an overall incidence of additional bone loss of greater-than-or-equal-to 2 mm of 23%, presence of an angular bony defect at baseline predicted longitudinal bone loss with 8% sensitivity, 94% specificity, 28% predictive value for the positive test and 77% predictive value for the negative test. It was concluded that, in absence of systematic peridontal therapy, the presence of an angular bony defect entails an increased risk for further alveolar bone loss.