Histological Improvement and Cytokine Levels Reduction in Patients with Oral Lichen Planus after Photobiomodulation Therapy.

Oral lichen planus (OLP) is a mucocutaneous disease associated with the formation of symptomatic lesions in the mouth that are often refractory to treatment. An as-yet-unknown antigen triggers an inflammatory reaction in which various immune and non-immune cells release multiple cytokines that contribute to disease progression. The ability of photobiomodulation (PBM) to reduce the symptoms and signs of the disease has been shown, but little is known about its molecular and cellular effects. The aim of this study was to evaluate changes in pro-inflammatory cytokine levels and in histological findings in OLP patients treated with photobiomodulation therapy. Twenty OLP patients underwent PBM with diode laser (810 nm), (0.50 W, 30 s, 1.2 J/cm), 3 times weekly for a month. Pain level and clinical scores of lesions were recorded before and after therapy. Salivary levels of IL-1β, IL-6, and TNF-α in OLP patients were measured before and after PBM and compared with those of 10 healthy controls. Biopsies were taken at the beginning and end of treatment to assess pathomorphological changes. PBM significantly reduced the level of pain and clinical scores of the lesions. Salivary levels of IL-1β, IL-6, and TNF-α in OLP patients were significantly higher compared to those in healthy controls and decreased after therapy. 60% of the post-treatment OLP biopsies demonstrated histological improvement, characterized by inflammatory infiltrate reduction (50%), epithelial hyperplasia reduction (30%), epithelial thickening (15%), or epidermal-dermal attachment repair (5%). The effectiveness of PBM therapy in OLP patients was confirmed at the clinical, molecular, and histomorphological levels.