The extent and severity of periodontal attachment loss are described for a random sample of 690 dentate community-dwelling adults, aged 65 or over, residing in five counties in North Carolina. In addition, risk indicators for serious levels of loss of attachment and pocket depth in this population are presented. Pocket depths and recession were measured on all teeth by trained examines during household visits. Blacks had an average of 78% of their sites with attachment loss and the average level of loss in those sites was approximately 4 mm, as compared to 65% and 3.1 min for whites. Because the extent and severity scores in this population were much higher than in younger groups, a serious condition in this group was defined as having 4+ sites of loss of attachment of 5+ mm with one or more of those sites having a pocket of 4+ mm. Bivariate analyses identified a large number of explanatory variables that were associated with increased likelihood of having the more serious periodontal condition. The logistic regression model for blacks includes the following important explanatory variables and associated odds ratios: use to tobacco (2.9), colony counts of B. gingivalis greater than 2% (2.4) and B. intermedius greater than 2% (1.9), last visit to the dentist greater than 3 years (2.3), and gums bleeding in the last 2 weeks (3.9). The model for whites indicated that tobacco use (6.2), presence of B. gingivalis (2.4) and the combined variable of having not been to the dentist in the last 3 years and having a high BANA score (16.8) were important explanatory variables.(ABSTRACT TRUNCATED AT 250 WORDS)