TNF and periodontal disorder: Periodontal disease, a frequently discussed cause of tooth loss, can stimulate the release of some cytokines which are related to the activation of molecules contributing to neurodegeneration, such as C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), immunoglobulin G (IgG), interleukin-1β (IL-1β), and interleukin-6 (IL-6) (Kamer et al., 2009; Koyama et al., 2013; Dursun et al., 2015; Liesz et al., 2015).