The prevalence of biologic implant complications, such as peri-implantitis, continues to increase with greater adoption of dental implant-supported restorations in clinical practice. Clarification of risk factors or indicators leading to peri-implant disease is necessary to provide clinicians more effective strategies for prevention and treatment. Despite heterogenous study designs, epidemiologic studies demonstrate using both direct and indirect measures that individuals with a history of periodontitis are at greater risk for biologic implant complications. The underpinning of an association between periodontitis and peri-implantitis has often been centered on bacterial biofilm, inflammation, and shared etiologic factors. Current microbiological studies do not support the premise of a distinct, or unique, etiologic biofilm composition, nor implicate a direct role of specific periodontal pathogens in peri-implant disease. The critical role of host immune response in initiation and progression of the periodontitis lesion may similarly act on the development of peri-implantitis. Shared etiologic factors, such as smoking, poor oral hygiene, and uncontrolled diabetes, may also play an important role in defining the association between periodontitis and peri-implantitis.