An approach to the definition of periodontal disease syndromes by cluster analysis.

Clinical syndromes of 22 untreated patients with advanced destructive periodontal disease were analyzed using cluster analysis. Clinical characteristics coded for each patient included age, sex, measures of gingival inflammation, plaque, suppuration, pocket depth, attachment level, extent and pattern of bone loss, rate of change in pocket depth, and correlation coefficients between certain clinical measurements. Microbiologic features included darkfield enumeration of 10 morphologically distinct forms of organisms which were removed from the three sites showing the most advanced destruction in each patient, as well as viable counts of specific microbial groups from the same teeth using elective and selective media. Serum antibody levels were determined by the ELISA technique to 13 species of subgingival microorganisms. The Gower coefficient was used to estimate similarity between patients and clusters were formed using an average unweighted linkage sort. Three distinct patient clusters were observed with greater than 70% average intra-cluster similarity. One subject did not fall into any of the patient clusters. The features which defined and differentiated the clusters were found to include age of subject, extent and patterns of bone loss, percent of sites showing change in pocket depth and attachment level, percent of small motile rods, intermediate spirochetes and fusiforms and serum IgG levels against Bacteroides gingivalis, Selenomonas sputigena and a Wolinella strain.