TNF and periodontitis: A large number of macrophages can be seen in the periodontal tissue of patients with periodontitis, and a large number of proinflammatory factors and bone resorptive factors, such as interleukin 1β, interleukin 6 (IL-6), and TNF-α, can be detected in gingival crevicular fluid (Lam et al., 2014).