This study aims to compare three treatment approaches for the erosive form of oral lichen planus, a chronic inflammatory condition that often causes pain, impaired oral function, and frequent relapses. Sixty adults with a confirmed diagnosis will be randomly assigned to photobiomodulation, Photodynamic Therapy, or topical clobetasol, which serves as the current standard of care. The project investigates how effectively each method promotes healing of erosive lesions, reduces pain, improves oral functions such as chewing and swallowing, and prevents recurrence after treatment. Before enrollment, participants will undergo microbiological testing, tissue autofluorescence assessment, and histopathological confirmation. Treatment will follow strict protocols tailored to each therapy type, with PBM applied twice weekly, PDT administered once weekly for six consecutive weeks using toluidine blue as a photosensitizer activated by a 635 nm diode laser, and clobetasol used twice daily for thirty days. Clinical outcomes will be measured using lesion size, standardized scoring systems, and patient-reported scales for pain and swelling. Follow up at one week, one month, and three months will document healing progress and relapse rates. Safety monitoring includes evaluation for infections and adverse reactions. The expected outcome is to determine which therapy provides the most effective, safe, and durable improvement. The study may offer evidence supporting laser based methods as alternatives that avoid the risks associated with long term steroid use.

The study investigates three therapeutic approaches for managing the erosive form of oral lichen planus, a chronic inflammatory disorder of the oral mucosa characterized by persistent mucosal damage, pain, and the risk of recurrent symptoms. The erosive phenotype is clinically significant because it often leads to functional limitations, such as difficulty eating, impaired tolerance of removable prostheses, and reduced quality of life. Standard therapy relies primarily on potent topical corticosteroids, yet this approach is frequently limited by incomplete remission, recurrence after withdrawal, and the potential for local adverse effects, including mucosal atrophy and secondary candidiasis. For these reasons, alternative treatment modalities have gained increasing clinical interest, particularly those based on light-based therapies capable of modulating cellular processes or removing pathologic tissue with minimal collateral injury. Photobiomodulation and Photodynamic Therapy represent two distinct applications of light energy. Photobiomodulation delivers low energy laser light that supports biological repair mechanisms, reduces inflammatory mediator activity, and enhances tissue regeneration without inducing thermal damage. PDT combines a photosensitizing agent with a light source of specific wavelength, which activates the photosensitizer to generate reactive oxygen species capable of selectively targeting pathologically altered tissue while limiting damage to surrounding healthy mucosa. This contributes to a reduction in lesion activity and supports mucosal recovery through localized cytotoxic and immunomodulatory mechanisms. Although each method has been investigated in smaller clinical series, direct comparisons among photobiomodulation, PDT, and topical corticosteroids remain limited, especially when applied to the erosive variant of oral lichen planus. The study follows a parallel group design with allocation governed by block randomization to maintain balanced group sizes. Participants undergo diagnostic workup before allocation to ensure accurate confirmation of the disease subtype and to exclude other mucosal disorders with overlapping features. Autofluorescence imaging is used as part of the diagnostic process to support precise selection of biopsy site and to assist in distinguishing inflammation from dysplasia or other pathology. Only patients with disease confined to the oral mucosa and without evidence of systemic illness that could influence healing potential proceed to treatment. Interventions are performed using standardized protocols that reflect current best practices for each modality. Photobiomodulation is delivered with a diode laser operating under controlled parameters designed to stimulate repair pathways. The PDT intervention uses toluidine blue as a photosensitizer applied under an occlusive dressing, followed by irradiation with a 635 nm diode laser to activate the photosensitizer and induce targeted cytotoxic effects within the affected mucosa. The control arm uses a topical corticosteroid formulation routinely employed in dental medicine for erosive lesions, with instructions provided to support maximal mucosal contact time. During the treatment period, clinicians document changes in lesion characteristics using standardized measurement tools that allow objective quantification of mucosal surface area and morphological alterations. Photographic records supplement clinical scoring to ensure consistency across follow up visits. Pain severity and functional disturbances are captured with validated numeric scales, supporting a comprehensive evaluation that includes both clinical and patient centered components. Follow up assessments take place after treatment completion to examine the durability of mucosal healing. Given that erosive oral lichen planus often recurs, these visits are critical to understanding whether any modality provides sustained remission. Monitoring includes microbiological evaluation to detect any changes in colonization patterns, such as the emergence of yeast species that may influence treatment response or cause secondary symptoms. Safety oversight focuses on identifying adverse reactions such as erythema, mucosal irritation, delayed healing, dyschromia, or any unexpected tissue responses. Light based methods are generally regarded as safe when applied within established energy ranges, yet ongoing surveillance helps detect rare events or individual sensitivities. The protocol outlines criteria for early discontinuation when significant symptom exacerbation or other concerning findings emerge. This study is structured to deliver high quality comparative data that can guide clinical decision making when standard therapy is insufficient, poorly tolerated, or contraindicated. By evaluating three therapeutically relevant modalities, the study seeks to determine which approach most effectively promotes epithelial recovery, reduces symptom burden, and supports functional comfort. Its focus on recurrence patterns adds an important dimension, as durable improvement is often challenging to achieve in erosive oral lichen planus. The results may clarify the advantages of low level laser applications, the immunomodulatory and antimicrobial properties of PDT, and the role of corticosteroids as a benchmark comparator. Photobiomodulation may demonstrate benefits related to noninvasiveness and absence of steroid related adverse effects. PDT may emerge as a precise alternative capable of controlling symptoms and accelerating mucosal healing through targeted photochemical action while avoiding systemic adverse effects. The study's methodology and extended observation window aim to support evidence based refinements to clinical protocols and promote therapeutic strategies aligned with patient comfort, safety, and long term disease control. The broader significance of the project lies in its potential to improve management of a chronic condition that has meaningful impact on daily activities and overall well being. By integrating structured clinical measurements, patient reported data, and advanced imaging methods, the study seeks to produce a comprehensive dataset that reflects contemporary standards in oral medicine research. The findings may pave the way for future work exploring predictors of treatment success, optimal photosensitizer concentrations and energy parameters for PDT, and potential combination approaches that incorporate both photobiomodulation and photodynamic tissue management.

Inclusion Criteria:

• Be between 20 and 70 years old.
• Have histologically confirmed erosive or ulcerative oral lichen planus based on a biopsy.
• Have no active aerobic bacterial infection or oral fungal infection.
• Have had no treatment for OLP within the past 3 months.
• Provide written informed consent.

Exclusion Criteria:

• Systemic diseases or conditions such as uncontrolled diabetes (random glucose ≥200 mg/dl), cardiovascular failure, or a pacemaker.
• Autoimmune/connective tissue diseases such as lupus with positive ANA testing.
• Current or past cancer, graft-versus-host disease, or hematologic disorders (anemia, leukemia, lymphoma, bleeding disorders, hemophilia, von Willebrand disease).
• Enzymatic or metabolic disorders such as G6PD deficiency (favism) or porphyria.
• Viral hepatitis A, B, or C.
• Recent vaccinations (within the past 6 months).
• Use of medications known to trigger lichenoid reactions, including:
• Antihypertensives (beta-blockers, diuretics, ACE inhibitors, centrally acting agents).
• Oral antidiabetics (sulfonylureas).
• Metal-containing compounds (lithium, gold, arsenic, mercury).
• NSAIDs (e.g., ibuprofen).
• Antibiotics/chemotherapeutics (tetracyclines, sulfonamides).
• Pregnancy or breastfeeding (including up to 6 months post-lactation).
• Photosensitivity to UV light.
• Smoking more than 5 cigarettes per day.
• Lesions located adjacent to amalgam fillings or metal prosthetic restorations.
• Any degree of dysplasia on histopathology.
• Treatment for OLP within the last 3 months.
• Active oral fungal or bacterial infection at screening.
• Lack of consent to participate.

Individual participant data will not be shared because the study involves sensitive clinical information and the protocol does not include provisions for external data distribution. Data access is limited to the research team to protect participant privacy and confidentiality.

Outcome assessments will be performed by an evaluator who is not involved in treatment delivery and will not have access to information identifying group assignment. Clinical measurements, lesion tracings, and photographic documentation will be coded before evaluation to maintain blinding. The assessor will review only de-identified data, ensuring that scoring of lesion size, mucosal features, and patient-reported measures is conducted independently of the intervention received.