EVALUATING THE EFFICACY OF PROBIOTICS IN TREATING ORAL LICHEN PLANUS: A SYSTEMATIC REVIEW OF CURRENT EVIDENCE

Objective: To systematically evaluate the clinical effectiveness, immunological outcomes, and safety of probiotic therapy in the management of oral lichen planus. Methods: A systematic review of randomized controlled trials was conducted following the PRISMA 2020 guidelines and registered with PROSPERO (CRD42024550624). Electronic searches were performed across multiple databases from January 2001 to March 2025. Trials assessing probiotic interventions in patients with clinically and/or histopathological diagnosed oral lichen planus were included. Risk of bias was assessed using the Cochrane RoB 2 tool with domain-level judgments, and certainty of evidence was evaluated using the GRADE approach. Results: Four randomized controlled trials involving 110 participants were included. Substantial heterogeneity was observed in probiotic strains, formulations, treatment regimens, and outcome measures. Probiotic monotherapy did not demonstrate consistent improvement in pain or lesion severity compared with placebo or standard therapy. In contrast, adjunctive probiotic use alongside topical corticosteroids were associated with greater pain reduction, improved lesion scores. Immunological assessments showed non-significant trends toward reduced inflammatory markers. All probiotic interventions were well tolerated, with no serious adverse events reported. Conclusion: Probiotics do not appear to provide consistent clinical benefit when used as monotherapy in oral lichen planus. Their role may be limited to adjunctive use, particularly in patients receiving topical corticosteroids, where benefits related to microbial balance and treatment tolerability may be observed. Given the low to very low certainty of evidence, small sample sizes, and methodological limitations, further well-designed randomized controlled trials are required.