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

ObjectiveThe aim of this systematic review and meta-analysis was to assess the role of smoking as a risk factor for peri-implantitis. Material and methodsSix 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 (2) and I-2 tests. The pooled effect was considered significant for a P-value <0.05. ResultsThe 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 ((2)=0.64, P=0.89; I-2=0% and (2)=2.44, P=0.30; I-2=18%, respectively, for implant- and patient-based meta-analyses). ConclusionThere 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.