A Case of Oral Lichen Planus; Unresponsive to Dental Metals Removal Despite the Suspected Diagnosis of Metal Allergy

Metal allergies can cause mucosal inflammation when triggered by dental materials. Oral lichen planus (OLP) is a chronic inflammatory disorder with multiple causes, including autoimmune factors, stress, and allergic reactions to dental metals. Differentiating between OLP and metal allergies in the oral cavity can be clinically challenging. This report presents a case initially suspected to be metal allergy but later confirmed as OLP. A 55-year-old female presented with redness and pain near the buccal gingiva of the right mandibular first molar, along with white lace-like patches. Intraoral examination revealed multiple metal restorations, and element analysis identified Zn and Co in several crowns. Based on these findings, a metal allergy was diagnosed. All metal crowns were replaced with zirconia. However, symptoms persisted. A biopsy later confirmed OLP, and steroid therapy was initiated. Despite removal of the suspected allergenic metals, the inflammation did not resolve, suggesting metal allergy was not the primary cause. Subsequent treatment with steroids led to gradual resolution, supporting the diagnosis of OLP as the primary condition. This case highlights the diagnostic difficulty in differentiating between metal allergy and OLP. Clinicians should consider OLP when symptoms persist despite metal replacement. A multidisciplinary approach is essential to achieve accurate diagnosis and effective treatment.