Systemic metronidazole in the treatment of periodontitis.

The present study evaluated the effect of systemic metronidazole on advanced periodontitis in 10 patients with inadequate oral hygiene. Clinical and microbiological observations were made at a total of 173 bleeding pockets of 5 mm depth or more. The clinical observations comprised plaque index scores, dichotomous measurements of gingival redness and suppuration, pocket depths and attachment levels. The microbiological variables investigated were the % spirochaetes, % black-pigmented Bacteroides species, % facultative streptococci and presence of absence of Bacteroides gingivalis. At baseline, after clinical measurements and microbiological samples had been taken, each patient received a thorough scaling and root planing. After 3 months, the clinical measurements and microbiological sampling were repeated and a 5-day course of metronidazole was administered while one side of the mouth was scaled and root planed. After a further 3 months, the final measurements and samples were taken. In comparing pre- and post-treatment data, the following significant differences were observed: for debridement alone, a reduction in mean % spirochaetes from 11.5% to 4.9% and an increase in mean % streptococci from 4.7% to 8.8%; for metronidazole alone, a 0.3 mm gain in mean attachment level, a 0.4 mm reduction in mean pocket depth and a reduction in the frequency of suppurating sites from 32% to 16%; for debridement plus metronidazole, a 0.2 mm gain in mean attachment level, a 0.5 mm reduction in mean pocket depth and a reduction in mean % spirochaetes from 5.6% to 2.5%. Thus systemic metronidazole, either alone or accompanied by debridement, produced a modest clinical improvement after debridement alone had failed.(ABSTRACT TRUNCATED AT 250 WORDS)