**8.2 History of periodontitis**

Patients who have lost teeth from periodontitis are treated with implants, and these patients may be more at risk of peri-implantitis disease. There is strong evidence from longitudinal and cross-sectional studies that a history of periodontitis constitutes a risk factor for peri-implantitis. Systematic reviews have indicated that subjects with a history of periodontitis are at greater risk of peri-implant disease. Long-term follow-up studies also revealed a correlation between peri-implantitis development with periodontitis [38–40].
