ABSTRACT
The role of specific Gram negative bacteria in the etiology and pathogenesis of periodontal disease has been markedly reported in the last two decades. This study evaluates the effect of local application of tetracycline or metronidazole on the subgingival bacterial as well as the clinical condition of the gingiva. Twenty four periodontitis patients were included in this study, each patient had either metronidazole or tetracycline, incorporated into acrylic strips inserted subgingivally once weekly for 3 weeks. Subgingival plaque samples were obtained from each patient immediately prior to insertion and after the removal of the strips. The collected bacterial plaque samples were cultured and identified. The results showed an improved gingival status and pocketing. Bacteriologically, the two drugs peoduced an increased number of cocci species with marked reduction of Gram negative rods, however metronidazole was more effective than tetracycline