Therefore, this study aimed to evaluate the effect of peri-implant therapy on the expression of cytokines related to Th17 response (GM-CSF, IFN-γ, IL-1β, IL-4, IL-6, IL-10, IL-12 (p70), IL-17A, IL-21, IL-23, and TNF-α) in the peri-implant crevicular fluid of patients with peri-implant mucositis and peri-implantitis after a three-month follow-up. Here, IL21 is linked to Peri-Implantitis.