Metronidazole: a double-blind trial in untreated human periodontal disease.

The effect of metronidazole was assessed in 20 subjects with untreated periodontitis, in a double-blind trial. Subjects received a 1-week course of drug or placebo immediately after baseline examination, and were reassessed 1 month and 3 months later. A 0.25 N constant force probe and darkfield microscopy were used. At 1 month, a difference was observed between the deepest individual pockets in experimental and control groups, with regard to change in probing depth and the proportions of non-motile organisms. At 3 months, differences were observed in 1-3 mm baseline pockets, where a greater proportion of control pockets increased in probing depth, and in 4-6 mm pockets, where a greater proportion of baseline bleeding pockets had ceased to bleed in the experimental group. The differences were of limited clinical significance when compared to studies where metronidazole was used as an adjunct to other therapy, and the results were equivocal with regard to the specific plaque hypothesis, since inhibition of connective tissue attachment loss was not unambiguously demonstrable.