Photodynamic Therapy with 5-Aminolevulinic Acid Versus Topical Corticosteroids in the Treatment of Oral Lichen Planus: A Randomized Clinical Trial with Lesion Site-Specific Analysis

<b>Objective</b>: Oral lichen planus (OLP) is a chronic immune-mediated condition of the oral mucosa, commonly associated with pain and burning sensations that impair quality of life. This study aimed to compare the efficacy of photodynamic therapy with 5-aminolevulinic acid (ALA-PDT) and topical glucocorticosteroids (CT) in the treatment of OLP, considering lesion location on keratinized and non-keratinized mucosa. <b>Materials and Methods</b>: A randomized clinical trial was conducted on 90 patients with histologically confirmed OLP. Participants were allocated to receive either ALA-PDT in addition to novel oromucosal emulgel containing 5% ALA (five weekly sessions) or clobetasol propionate applied twice daily for two weeks. Lesion area, clinical severity (Reticulation, Erythema, Ulceration-REU index), and subjective symptoms (Visual Analog Scale-VAS) were evaluated before treatment, immediately after, and six months after therapy. <b>Results</b>: ALA-PDT achieved significantly greater and more durable reductions in lesion area, REU scores, and VAS values compared to CT, particularly on non-keratinized mucosa (mean lesion reduction from 2.64 to 0.56 cm² at six months; <i>p</i> < 0.0001). CT therapy showed initial improvement but was followed by relapse at six months. Both treatments were well tolerated, with only mild transient adverse effects reported. <b>Conclusions</b>: ALA-PDT, especially when applied to non-keratinized oral mucosa, provides superior and longer-lasting therapeutic outcomes than topical CT. The application of novel ALA-loaded emulgel enhances treatment efficacy and tolerability, supporting PDT as a promising alternative for OLP management.