Treatment of periodontal infections due to anaerobic bacteria with short-term treatment with metronidazole.

In the present report, five selected periodontal patients were treated for 1 week with metronidazole. Two of the patients had their teeth scales and root-planed the week they received metronidazole. Prior to treatment, B. asaccharolyticus accounted for 41% of the cultivable isolates and the spirochetes averaged 29% of the microscopic count in plaque removed from each of four pockets per patient. The presence of these elevated proportions of periodontopathic bacteria combined with the presence of periodontal pockets and attachment loss suggested that the patients were in a state of an active infectious process involving primarily anaerobic bacteria. If this be the case, then antimicrobial therapy directed against these anaerobes wih metronidazole was indicated. The 1-week treatment with metronidazole significantly reduced the proportions of these organisms for up to 6 months after treatment. Coincident with these findings was an improvement in the clinical parameters, especially in those sites that initially had greater than 5 mm pocket or attachment loss. These sites showed a 2 mm or more reduction in pocket depth and an almost 2 mm gain in apparent attachment that was evident 6 months after treatment. The results obtained were in only five patients. However, the magnitude of improvement suggests that antimicrobial therapy directed against anaerobic organisms may be a valuable adjunct to periodontal therapy.