IL6 and periodontitis: It has been reported that patients with periodontitis displayed increased levels of IL‐6 and TNF‐α in inflamed gingival tissues, gingival crevicular fluids, and sera than the healthy controls (Takahashi et al., 1994; Lee et al., 1995; Tervahartiala et al., 2001; Kurtiş et al., 2005; Shimada et al., 2010).