Long-Term Changes in Salivary Oxidative and Nitrosative Stress Biomarkers After Photodynamic Therapy Versus Clobetasol in Oral Lichen Planus: A Randomized Clinical Trial

Background: Oxidative and nitrosative stress may contribute to the pathogenesis of oral lichen planus (OLP). This study compared the effects of photodynamic therapy (PDT) and topical corticosteroid therapy (CT) on selected salivary redox biomarkers. Materials and Methods: Thirty-nine patients with OLP were randomized to five weekly sessions of 5-aminolevulinic acid PDT (n = 20) or topical clobetasol applied for 14 days (n = 19). Salivary advanced oxidation protein products (AOPP), advanced glycation end products (AGE), 3-nitrotyrosine (NT), and peroxynitrite (PN) were measured before treatment, immediately after treatment, and after 6 and 12 months. Associations with lesion area and pain intensity were also assessed. Results: PDT significantly reduced AOPP concentrations, which remained below baseline throughout follow-up and were lower than after CT at all post-treatment assessments. AGE increased transiently after PDT but decreased thereafter and was lower than after CT at 12 months. NT was lower after PDT than after CT immediately after treatment. PN concentrations showed significant within-group changes over time in the CT group; however, baseline PN concentrations differed between the treatment groups, limiting direct interpretation of between-group differences. Biomarker concentrations showed no consistent associations with lesion area or pain intensity. Conclusions: PDT and CT were associated with different patterns of change in selected salivary redox biomarkers in OLP. PDT was particularly associated with a sustained reduction in AOPP concentrations, whereas the investigated biomarkers showed no consistent relationship with clinical disease severity.