TNF and periodontitis: In addition, periodontitis can cause changes in the structure of the periodontium due to the inflammation maintained over time in the periodontal ligament, the increase in metalloproteases that destroy the dental support tissue, and the increase in inflammatory cytokines; interleukins (ILs) 1β, 4, 6, 7, and 17; tumor necrosis factor alpha (TNF-α); and C-reactive protein (CRP).