Oxidative stress and antioxidant defense in oral lichen planus and oral lichenoid reaction

Background. Oral Lichen Planus (OLP) is an inflammatory disease of unknown etiology while Oral Lichenoid Reaction (OLR) is a condition mimicking OLP. As these conditions are exposed to oxidative stress, they could release reactive oxygen species (ROS) which are implicated in the pathogenesis of a plethora of inflammatory conditions to lethal diseases. We evaluated and compared the levels of a series of oxidative stress markers in patients with OLP and OLR with that of normal controls and tried to identify the role of these oxidative stress markers in these conditions. Methods. Protein thiol oxidation, malondialdehyde (MDA) and total antioxidant activity were estimated in both the groups (OLP and OLR) and compared with that of normal subjects. Results. There were significantly lower levels of serum protein thiols in OLP (p < 0.005) while in patients with OLR the difference was not statistically significant (p < 0.489) when compared with controls. Serum MDA levels were significantly higher in OLP (p < 0.001) and OLR (p < 0.001) than in controls. However, there was no significant difference in serum MDA levels between OLP and OLR patients (p > 0.05), but with a significant difference in serum thiol levels between the two (p < 0.047). Total antioxidant levels were lower in OLP (p < 0.016) and OLR (p < 0.017) when compared to normal subjects, while between the study group total antioxidant levels were not significantly different (p < 0.632). Conclusions. The findings from the present study demonstrate involvement of ROS in the pathogenesis of OLP and OLR, though both these disease conditions have a different clinical course.