Recently, Ghassib et al. (2019) [21], in a systematic review, compiled data from nineteen studies that assessed the levels of IL-1β, IL-6, TNF-α, and/or matrix MMP-8 in the crevicular fluid of healthy implants, peri-implant mucositis, and peri-implantitis. The gene discussed is TNF; the disease is Peri-Implantitis.