Effects of Local Application of Tetracycline with Hydrophilic Base on Subgingival Microflora

The present investigation was conducted to assess the effect of tetracycline, locally administered using root canal syringe, on subgingival microfiora. Eight adult volunteers with clinical diagnosis of periodontitis were used in the study. Each volunteer had at least a pair of teeth with periodontal pockets of 4mm or more. Tetracycline was formulated in hydrophilic paste at a concentration of 3 percent. The tetracycline paste or placebo was delivered into periodontal pockets using a root canal syringe every 2 days for 2 weeks on double blind basis. Subgingival bacterial samples were obtained with paperpoints from each sites and the bacterial examination consisted of phase-contrast microscopic counting. During the 14-day application of tetracycline, periodontal pockets of test sites showed a significant reduction in total cell counts. The concomitant reduction of spirochetes and an increase in coccoid cells were also statistically significant. Pocket depth, gingival index and sulcular bleeding index in experimental sites were improved significantly during the trial. These data suggest that the syringe delivery system of tetracycline is effective in controling subgingival plaque and in reducing periodontal inflammation.