TNF and Peri-Implantitis: Furthermore, the increased bacterial challenge and the subsequent chronic inflammatory reaction will result in an increase in the expression of inflammatory mediators, such as interleukin (IL)-1β, IL-6, IL-8, or tumor necrosis factor (TNF)-α, which, when present at high concentrations in the peri-implant crevicular fluid samples, have been correlated with peri-implant disease severity [13,14,15,16] and, conversely, its reduction with a successful peri-implantitis resolution [17].