Effect of adjuvant use of metformin on periodontal treatment: a systematic review and meta-analysis.

OBJECTIVE: The aim of the study was to perform a systematic review of the literature regarding the adjuvant effects of metformin on the results of mechanical periodontal treatment. METHODS: First, a search on the PubMed, EMBASE, and Scopus databases was performed up to March 2018. Randomized clinical trials with at least 3 months of follow-up and using metformin associated with mechanical periodontal treatment were included in the review. As comparison group, mechanical or periodontal therapy alone or in combination with placebo. The studies should involve adults with at least 30 years of age diagnosed with chronic periodontitis. For the evaluation of the risk of bias of the articles, the Cochrane Collaboration tool was used. RESULTS: Studies (1912) were retrieved and 4 were included in the review. The articles are all from the same research center and used metformin in gel at concentrations of 0.5%, 1%, or 1.5%. The majority of included studies presented low risk of bias. A linear meta-analysis was conducted for probing depth and clinical attachment loss outcomes. The results showed a weighted mean difference of 2.12 mm (95% CI 1.83-2.42) and 2.29 mm (95% CI 1.72-2.86) for probing depth and clinical attachment level, respectively, favoring the group exposed to 1% adjunct metformin. CONCLUSION: The adjuvant use of metformin may promote an additional benefit to the results of mechanical periodontal therapy. CLINICAL SIGNIFICANCE: The metformin as an adjuvant on periodontal treatment shows potential to reduce needs of additional interventions and also reduces the inflammatory burden in patients.