IFNG and oral lichen planus: Conversely, the meta-analysis of Mozaffari et al. pointed out that no significant differences in IFN-γ levels were observed in OLP patient serum and saliva in comparison to controls [45]; however, several other studies proved that there is a strong IFN-γ presence in infiltrating lymphocytes in OLP patients’ saliva compared to controls [41,46,47].