The effects of subgingival irrigation with low dosage metronidazole on periodontal inflammation

The effects on chronic periodontitis of a simplified oral hygiene regimen combined with subgingival irrigation with 0.5% metronidazole were investigated. 19 patients, with 548 pockets greater than or equal to 4 mm, completed a 3-month randomised double-blind placebo-controlled trial. At day 0, prior to treatment, and at days 7, 28, 56 and 84, plaque index, sulcus bleeding index and probable pocket depth were recorded. The simplified oral hygiene regimen consisted of (1) one episode of root debridement, removal of subgingival approximal overhangs on restorations and subcontact area debridement with abrasive strips and polishing, and (2) instruction in Bass brushing (twice daily) with no stress on interdental cleaning. After baseline debridement, patients were allocated 0.5% metronidazole or a placebo. They were instructed to irrigate subgingivally once daily for 28 days. Treatment resulted in marked improvement in both groups and proportionately more sites improved in the metronidazole group at 28, 56 and 84 days. There were no significant differences between the procedures at any time. It was concluded that a simplified oral hygiene regimen combined with daily subgingival irrigation with 0.5% metronidazole or a placebo was effective in reducing periodontitis for at least a further 8 weeks, and that proportionately more sites improved in the metronidazole group.