TNF and oral lichen planus: The results of previous studies on TNF‐α are conflicting, although mostly showing elevated levels in patients with OLP compared to healthy controls (Kaur & Jacobs, 2015; Kondo & Urisu, 2009; Lu et al., 2013; Pekiner et al., 2012; Simark‐Mattsson et al., 1999; Zhou et al., 2009).