MMP8 and Peri-Implantitis: Diagnostic studies and technologies attempting to utilize total MMP-8 as a diagnostic biomarker for periodontitis and peri-implantitis have shown contrasting outcomes as some of the studies have revealed relatively good diagnostic ability of total MMP-8 to discriminate periodontal and peri-implant health and disease, while many others have clearly shown the opposite [33,34,35,36,37,38,39,40,41,42].