Oral lichen planus is an idiopathic chronic mucocutaneous disease with a ride range of clinical manifestations, including white reticular patches, erosive/ulcerative and atrophic lesions, both associated with intense symptomatology. CD4+ and CD8+ T lymphocytes cells play an important role in the pathogenesis of OLP and are responsible for the production of different cytokines, including IL-6, IL-10, IL-1β, INF-γ and TNF-α. Treatment is symptomatic and topical corticosteroids are commonly used as standard therapy. However, patients frequently present relapses after treatment's discontinuation, develop resistance to corticosteroids therapy as well as secondary candidiasis. Photobiomodulation (PBM) has shown to be a potential therapeutic tool to treat inflammatory disorders, including OLP. Some studies have demonstrated that PBM improves the clinical presentation of OLP (erosive/ulcerative or atrophic lesions to reticular lesions), reduces pain and recurrence. However, it remains controversy if PBM is more effective than corticosteroid in the treatment of OLP. The aim of this study is to evaluate the efficacy of PBM in the treatment of OLP in relation to the standard therapy with corticosteroids. This is a protocol for a randomized, controlled, doubled blind clinical trial, with two months of follow up.
Patients with symptomatic OLP and with histopathological diagnosis of OLP based on WHO criteria will be included in this study. Fourty-four patients will be randomized in two experimental groups. Control group will be treated with clobetasol propionate 0.05% gel for 30 consecutive days and the laser device will be positioned over the lesion but will be switched off to mask the treatment. The experimental group will be treated with placebo gel for 30 consecutive days to mask the treatment and patients will receive laser treatment twice a week during 1 month for PBM (laser λ = 660±10 nm; power 100mW; radiant energy; 177J/cm2; 5-s exposure time per point and 0.5J of energy per point). The primary variable (pain by VAS scale) and the secondary variables (clinical scores, functional scores and Patient anxiety and depression) will be evaluated at the baseline, once a week during treatment and after 30 and 60 days of follow up. Evaluation of clinical resolution will be performed at the end of the treatment (30 days). Evaluation of recurrence will be performed after 30 and 60 days of follow up. Serum and salivary levels of IL-6, IL-10, IL-1β, INF-γ and TNF-α will be evaluated at baseline and at the end of treatment (30 days). Quality of life will be evaluated by OHIP-14 questionnaire at baseline, at the end of treatment and after 30 and 60 days of follow up. The findings will be computed and submitted to statistical analysis. Interval estimates will be used for the variables of interest to determine the prevision of the estimates and perform comparisons. If necessary, transformation methods or non-parametric tests will be applied. The chi-square test, Student's t-test and ANOVA will be used and the level of significance of 5% will be considered (p \< 0.05).
