Hypersensitivity reactions to dental materials in patients with lichenoid oral mucosal lesions and in patients with burning mouth syndrome.

Epicutaneous patch testing of a battery of 35 dental test substances was carried out in 24 patients with visible lichenoid oral mucosal lesions and in 24 patients with burning mouth syndrome (BMS) without any visible lesions. Reactions to mercury ammonium chloride were found in 33% (8/24) of the patients with visible lesions compared to 0% (0/24) of the patients with BMS. The difference was statistically significant. In 7 of the 8 patients who reacted to mercury, total or partial regression of the lesions was observed after removal of dental amalgam. Reactions to nickel sulfate were found in 21% (5/24) of the patients with BMS compared to 3% (1/24) of the patients with lichenoid lesions. This difference was also statistically significant. Nickel is a rare component in dental restorations, but the oral mucosa is daily exposed to nickel through food and water intake. Removal of nickel from the environment of the patient can therefore be hard to accomplish.