Relationship of subgingival microbial complexes to clinical features at the sampled sites

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Abstract
Subgingival plaque samples from 100 active destructive periodontal lesions and 150 inactive subgingival sites in 33 subjects were analyzed by predominant cultivable microbiota techniques, 50 isolates were characterized from each sample and where possible, the isolate was placed in 1 of 134 microbial species or groups. The sites were clustered on the basis of the proportions of all of the species detected in each sample using a minimum similarity matching coefficient and an average unweighted linkage sort. 10 clusters containing 166 sites were formed which exhibited > 35% minimum similarities. All clusters were made up of sites from multiple subjects and were formed on the basis of different combinations of micro–organisms. Certain complexes of microorganisms appeared to relate to the severity of periodontal destruction and the activity of the sampled site. The combination of F. nucleatum, B. forsyth and W. recta (cluster VII) or B. gingivalis, B. intermedius and S. intermedius (cluster VIII) distinguished clusters made up of sites which on average had the most attachment loss and the deepest pockets. These clusters contained the highest proportions of active sites and sites which lost > 3 mm of attachment after therapy. Clusters dominated by V. parvula (cluster III), the Actinomyces sp. (cluster X) or the combination of S. sanguis II, S. mitis, V. parvula and S. intermedius (cluster II) were made up of sites which exhibited less active disease and responded more favorably to therapy. Sites in other clusters exhibited moderate levels of prior destructive disease and disease activity status closer to the mean values for all 250 sites. These clusters were dominated by S. intermedius, E nucleatum and E. corrodens; F. nucleatum., S. intermedius, E. corrodens and W. recta; S. xylosusi; B. inlermedius and E. corrodens; C. oehracea, W. recta and B. intermedius. 83% of sites from refractory subjects fell into cluster groups, but only 53% of sites from subjects who responded well to therapy, suggesting a greater homogeneity of the microbiotas in subgingival sites of refractory subjects. The cluster analysis suggested complexes of micro‐organisms which might merit further investigation in human clinical studies as well as in mixed infection models.