Relation of baseline microbial parameters to future periodontal attachment loss

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Abstract
The relationship between the level of subgingival species at baseline and subsequent attachment loss in a subject was examined. 38 subjects (14–71 years) with prior evidence of periodontal destruction were monitored 2 × for pocket depth and attachment level at 6 sites per tooth at baseline and 2 months. A subject was considered to exhibit new attachment loss if 1 or more sites increased 3 mm or more in attachment level in 2 months. Subgingival plaque samples were taken at the baseline visit from the mesial aspect of each tooth (28 sites) using Gracey curettes. Samples were dispersed, diluted and plated on Trypticase soy agar supplemented with 5% sheep blood. After 7 days of anaerobic incubation, the colonies were lifted onto nylon filters, lysed and the DNA fixed to the filters. Digoxygenin‐labeled DNA probes were used to enumerate 14 subgingival species. 17 of 38 subjects (44.7%) exhibited new attachment loss in 2 months. The % of the total viable count of each species was averaged for each subject. The species enumerated and the mean % of the total cultivable microbiota averaged across the active and inactive subjects were as follows; B gingivalis 2.3, 1.2; W. recta 1.3, 0.6; B. intermedius I.2.5, 2.0; B. forsythus 1.5, 1.2; A. actinomycetemcomitans serotype a 1.1, 0.8; F. nucleatum ss vincentii 1.1, 1.0; S. intermedius 2.0, 1.9; P. micros 1.5, 1.5; B. intermedius II 1.6, 1.7; A. actinomycetemcomitans serotype b 0.4, 0.6; S. sanguis I 1.8, 2.1; S. sanguis II 2.7, 3.0; V. parvula 3.9, 4.2; C. ochracea 0.9, 1.8. Significantly higher levels of B. gingivalis and W. recta and significantly lower levels of C. ochracea were found in active subjects prior to breakdown. Odds ratios were computed at different threshold levels for each species. Significant ratios for new disease were B. gingivalis 5.6, W. recta 3.8, V. parvula 0.16 and C. ochracea 0.08. When subjects were subset into those with localized (< 30% affected sites) and widespread disease groups, B. gingivalis and B. intermedius I were elevated in active localized disease subjects and C. ochracea in inactive subjects. P. micros and W. recta were elevated in active widespread disease subjects. Discriminant analysis using the significantly related species was useful in predicting subjects at risk for new attachment loss overall and in both groups. Such data suggest that levels of microorganisms may be useful indicators of future attachment loss.