OBJECTIVES: To test the null hypothesis of no difference in the implant failure rates, postoperative infection, and marginal bone loss for the insertion of dental implants in periodontally compromised patients (PCPs) compared to the insertion in periodontally healthy patients (PHPs), against the alternative hypothesis of a difference. METHODS: An electronic search without time or language restrictions was undertaken in March 2014. Eligibility criteria included clinical human studies, either randomized or not. RESULTS: 2768 studies were identified in the search strategy and 22 studies were included. The estimates of relative effect were expressed in risk ratio (RR) and mean difference (MD) in millimetres. All studies were judged to be at high risk of bias, none were randomized. A total of 10,927 dental implants were inserted in PCPs (587 failures; 5.37%), and 5881 implants in PHPs (226 failures; 3.84%). The difference between the patients significantly affected the implant failure rates (RR 1.78, 95% CI 1.50-2.11; P<0.00001), also observed when only the controlled clinical trials were pooled (RR 1.97, 95% CI 1.38-2.80; P=0.0002). There were significant effects of dental implants inserted in PCPs on the occurrence of postoperative infections (RR 3.24, 95% CI 1.69-6.21; P=0.0004) and in marginal bone loss (MD 0.60, 95% CI 0.33-0.87; P<0.0001) when compared to PHPs. CONCLUSIONS: The present study suggests that an increased susceptibility for periodontitis may also translate to an increased susceptibility for implant loss, loss of supporting bone, and postoperative infection. The results should be interpreted with caution due to the presence of uncontrolled confounding factors in the included studies, none of them randomized. CLINICAL SIGNIFICANCE: There is some evidence that patients treated for periodontitis may experience more implant loss and complications around implants including higher bone loss and peri-implantitis than non-periodontitis patients. As the philosophies of treatment may alter over time, a periodic review of the different concepts is necessary to refine techniques and eliminate unnecessary procedures. This would form a basis for optimum treatment.