Adjunctive efficacy of systemic metronidazole in the surgical treatment of periodontitis: a double-blind parallel randomized clinical trial

Objectives The purpose of this study was to evaluate the clinical and microbiological impact of adjunctive metronidazole to periodontal surgery. Materials and methods Systemically healthy patients, with stages III–IV, grades B–C periodontitis, were randomly assigned to receive metronidazole or placebo adjunctive to periodontal surgery, after subgingival instrumentation. Clinical variables were recorded at the initial visit, 6 weeks after subgingival instrumentation, and 3, 6, and 12 months after surgery. Microbiological samples were taken at initial and final visits and analyzed by quantitative polymerase chain reaction. Results Our results showed no statistically significant differences in the reduction of probing depth between the initial and final (1 year) visits in the two treatment groups. Additionally, no statistically significant differences were observed between study groups when comparing the post-subgingival instrumentation and final visits. However, 3 months after surgery, probing depth (mean difference, MD = 0.31 mm, 95% confidence interval, CI [0.13; 0.49]; p = 0.001) and clinical attachment level ( MD = 0.64 mm, 95% CI [0.02; 1.27]; p = 0.044) were significantly lower in the test group. Conclusions The adjunctive use of systemic metronidazole to periodontal surgery has a limited clinical and microbiological impact in the present study, and therefore, its use is not recommended. Clinical relevance There are no studies that have evaluated the clinical and microbiological impact of the adjunctive use of systemic metronidazole to periodontal surgery (step 3 of periodontal therapy). The results of the present study do not support the adjunctive use of systemic metronidazole to periodontal surgery.