Response to periodontal therapy in patients with high or low levels of P-gingivalis, P-intermedia, P-nigrescens and B-forsythus

In a previous study, subjects receiving either adjunctive tetracycline or Augmentin showed, on average, more attachment level gain 10 months posttherapy than subjects receiving either Ibuprofen or a placebo, although some subjects in each treatment group showed loss of attachment post-therapy. Since differences in treatment response might have been due to differences in the subgingival microbiota, the response to different therapies in subjects with different pre-therapy subgingival microbiotas was evaluated. 29 subjects exhibiting loss of attachment >2.5 mm at 1 or more sites during longitudinal monitoring were treated by modified Widman flap surgery at deep sites, subgingival scaling at all other sites and were randomly assigned one of the following agents: Augmentin, tetracycline, ibuprofen or a placebo. Treatment was completed within 30 days, during which time the subject took the assigned agent. Subgingival plaque samples were taken from the mesial surface of each tooth at each visit and evaluated for their content of 14 subgingival species including P. gingivalis, P. nigrescens, P. intermedia and B. forsythus using DNA probes. 18 subjects with mean counts >10(5) of 2 or more of these 4 species comprised the high test species group; 11 subjects with mean counts >10(5) of 0 or 1 of the species, the low test species group. Because this was a post-hoc analysis, the number of subjects in some of the treatment/test species groups was small. However, the 8 high test species subjects who received tetracycline showed the most attachment level gain (0.83+/-0.20 mm), while the 3 tetracycline-treated, low test species subjects showed minimal gain (0.05+/-0.28 mm) 10 months post-therapy. Low test species subjects receiving Augmentin (n=2) showed a mean gain in attachment of 0.67 (+/-0.59) mm. The mean % of sites showing either attachment gain or loss greater than or equal to 2 mm was computed for each treatment/test species group. High test species subjects receiving tetracycline exhibited the best ratio of gaining to losing sites (16.2), followed by low test species subjects receiving Augmentin (14.1). Periodontal pockets <7 mm pre-therapy in low test species subjects treated with Augmentin and high test species subjects treated with tetracycline showed attachment gain more frequently than attachment loss. The greatest proportion of gaining sites was seen at pockets >6 mm, particularly in subjects receiving adjunctive tetracycline. Overall, the data indicated that a gain in mean attachment level post-therapy was significantly associated (p<0.001) with an increase in C. ochracea accompanied by a decrease in B. forsythus, P. gingivalis, P. intermedia and P. nigrescens. The 4 test species were decreased more in subjects receiving tetracycline. In contrast, Augmentin appeared to be effective in decreasing the % sites colonized by A. actinomycetemcomitans and in increasing the proportion of sites colonized by C. ochracea. Knowledge of the baseline microbiota should improve the choice of an appropriate adjunctive antibiotic for periodontal therapy.