The effect of metronidazole on human periodontal disease. A clinical and bacteriological study.

Fifteen female subjects undergoing treatment for nonspecific vaginitis with metronidazole 250 mg q.i.d. for 7 days were studied. Clinical and microbiological evaluations were carried out initially and at 2 and 4 weeks. The following parameters were measured in two quadrants: plaque index, sulcular bleeding index, pocket depth, attachment level and amount of gingival fluid. Dark field microscopy was used to quantitate the plaque constituents. One quadrant was subjected to root planing at the initial visit; the other quadrant received no therapy. No oral hygiene instructions were given. All the clinical parameters were significantly reduced in all areas. Gingival fluid, sulcular bleeding index and pocket depth showed greater improvement in the root-planed quadrant compared to the nonroot-planed quadrant. Dark field microscopy showed decreases in fusiforms, curved rods and spirochetes in all areas with a concomitant increase in cocci. The root-planed quadrant showed no significant differences in microbiological aspects when compared to the nonplaned quadrant. Clinically, metronidazole therapy resulted in improvement of periodontal status with some additional but small enhancement due to root planing. Microbiologically, metronidazole dramatically changed the quality of plaque with no supplemental effect when root planing was added.