Levels of smoking and dental implants failure: A systematic review and meta-analysis.

AIM: The present systematic review and meta-analysis was performed to investigate if there was a significantly enhanced risk of dental implant failure due to the increased number of cigarettes smoked per day. MATERIALS AND METHODS: Four databases, including PubMed, Embase, Web of Science and Scopus, were searched until January, 2019. The search terms "dental implant, oral implant, smoking, smoker, tobacco, nicotine and non-smoker" were used in combination to identify the publications providing data for dental implant failures related to the smoking habit. Publications were excluded if the quantity of cigarettes consumed per day was not reported. Fixed- or random-effects meta-analyses were used to pool the estimates of relative risk (RR) with 95% confidence intervals (CI). RESULTS: Having additional information supplied by the authors, 23 articles were selected for final analysis. The meta-analyses based on implant- and patient-related data showed a significant increase in the RR of implant failure in patients who smoked >20 cigarettes per day compared with non-smokers (implant based: p = .001; RR: 2.45; CI: 1.42-4.22 and patient based: p < .001; RR: 4; CI: 2.72-5.89). CONCLUSION: The risk of implant failure was elevated with an increase in the number of cigarettes smoked per day.