Dreyer H, et al. - The prevalence, incidence and risk factors of peri-implantitis were investigated via performing this systematic review and meta-analysis of the current literature. Overall, the prevalence of peri-implantitis on implant level ranged from 1.1% to 85.0% and the incidence from 0.4% within 3 years, to 43.9% within 5 years, respectively. Medium and medium-high level of evidence suggested smoking, diabetes mellitus, lack of prophylaxis and history or presence of periodontitis as risk factors of peri-implantitis. Medium-high evidence suggested that patient’s age, gender and maxillary implants had no correlation with peri-implantitis. No convincing or low evidence was available identifying osteoporosis, absence of keratinized mucosa, implant surface characteristics or edentulism as risk factors for peri-implantitis.