Smoking and the risk of peri‐implantitis. A systematic review and meta‐analysis

OBJECTIVE: The aim of this systematic review and meta-analysis was to assess the role of smoking as a risk factor for peri-implantitis. MATERIAL AND METHODS: Six electronic databases and a manual search resulted in 5876 unique publications. After selection, only seven studies were included in the systematic review. Dichotomous data were expressed as risk ratios (RRs) and 95% confidence intervals (CIs). A generic inverse variance statistical model was used. Due to the expected interstudy heterogeneity, a random effect model was used for both data types. Heterogeneity was assessed with the Cochrane χ(2) and I(2) tests. The pooled effect was considered significant for a P-value <0.05. RESULTS: The implant-based meta-analysis revealed a higher and significant risk of peri-implantitis in smokers (RR: 2.1, 95% CI: 1.34-3.29, P = 0.001) compared with nonsmokers, but the patient-based meta-analysis did not reveal any significant differences for risk of peri-implantitis in smokers (RR: 1.17, 95% CI: 0.78-1.75, P = 0.46). No evidence of significant heterogeneity was detected for the two analyses (χ(2) = 0.64, P = 0.89; I(2) = 0% and χ(2) = 2.44, P = 0.30; I(2) = 18%, respectively, for implant- and patient-based meta-analyses). CONCLUSION: There is little evidence that smoking is a risk factor for peri-implantitis. However, given the low number of included studies, future studies are needed to confirm these results.