Based on the available evidence, it can be concluded that although some studies do not find a relationship between IL-1β, TNF-α, and PGE2 levels in PICF and peri-implantitis, most of them, as evidenced in systematic reviews and clinical studies, demonstrate a positive association between elevated concentrations of these biomarkers in the PICF of diseased versus healthy sites [20,22,23,32,33,53,54]. This evidence concerns the gene TNF and Peri-Implantitis.