No evidence of hypersensitivity to dental restorative metals in oral lichen planus

Twelve patients with oral lichen planus (OLP) suspected of dental restorative metal allergy were examined. All patients were patch tested with several metals including six different mercury compounds. One (8%) patient showed a positive patch test to two mercury compounds whereas no mercury allergy was found in a reference group of 17 patients suspected of dental restorative material allergy but without OLP lesions. The mercury allergic OLP patient was further tested on palatal mucosa but no reactions developed. Moreover, the energy dispersive X-ray microanalysis failed to show any contaminating metals in his OLP lesion. Mucosal biopsies were taken in close contact with amalgam fillings from nine OLP patients but these disclosed no evidence of lichenoid or dysplastic alterations. In OLP lesions, the immunofluorescence findings showed fibrinogen deposition, altered basement membrane and elastic fiber staining and intense Ulex europeaus I lectin fluorescence through all epithelial cell layers. Therefore, the present patch tests did not reveal increased frequency of mercury or other metal allergy in OLP patients and the mucosal biopsies failed to show any histologic or immunofluorescence alterations deviating from idiopathic OLP lesions.