AIM:This study aimed to evaluate and compare the performance of two methodological instruments to appraise systematic reviews and to identify potential disagreements of systematic review authors regarding risk of bias (RoB) evaluation of randomized controlled trials (RCTs) included in systematic reviews on peri-implant diseases. MATERIAL/METHODS:We searched Medline, Web of Science, Cochrane Library, PubMed Central, and Google Scholar for systematic reviews on peri-implant diseases published before July 11, 2017. Two authors independently evaluated the RoB and methodological quality of the systematic reviews by applying the Risk of Bias in Systematic Reviews (ROBIS) tool and Assessing the Methodological Quality of Systematic Reviews (AMSTAR) checklist, respectively. We assessed the RoB scores of the same RCTs published in different systematic reviews. RESULTS:Of the 32 systematic reviews identified, 23 reviews addressed the clinical topic of peri-implantitis. A high RoB was detected for most systematic reviews (n=25) using ROBIS, whilst five systematic reviews displayed low methodological quality by AMSTAR. Almost 30% of the RoB comparisons (for the same RCTs) had different RoB ratings across systematic reviews. CONCLUSIONS:The ROBIS tool appears to provide more conservative results than AMSTAR checklist. Considerable disagreement was found among systematic review authors rating the same RCT included in different systematic reviews.