In patients with OLP, increased concentrations of lipid and DNA oxidation products such as malondialdehyde (MDA) and 8-hydroxy-2′-deoxyguanosine (8-OHDG) have been reported, along with decreased activity of key antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD), peroxidase (Px), and reduced glutathione (GSH) [23,24,25,26,27,28,29,30,31,32,33]. This evidence concerns the gene CAT and oral lichen planus.