A large number of clinical studies and systematic reviews have demonstrated that gene polymorphisms in IL-1B, IL-1R (which encodes the IL-1-associated receptor) and IL-1N (which encodes the receptor antagonist IL-1Ra) are related to a susceptibility to periodontitis,35 which indicates that IL-1β is involved in the pathogenesis of periodontitis. Here, IL1R1 is linked to periodontitis.