Amalgam-associated oral lichenoid reactions. Clinical and histologic changes after removal of amalgam fillings

Forty-nine consecutive patients with clinically diagnosed oral lichenoid reactions in contact with amalgam fillings were studied clinically and histologically. The long-term effect of replacement of these fillings was also examined.

Seventeen (35%) patients showed positive reactions to mercury at the epicutaneous patch test that was carried out before treatment. After treatment, total regression of the lesions was found clinically in 33 (69%) and histologically in 26 (55%) patients. Most of the remaining lesions changed clinically and histologically to a less pronounced tissue reaction. Lesions in direct contact with amalgam fillings (group I) showed significantly better healing results than lesions that exceeded the contact area (group II). No difference in healing capacity was noted in the two groups between patients with positive patch reactions to mercury compared with those with negative reactions. Lesions that histologically were classified as benign oral keratosis showed a similar healing pattern as those classified as oral lichen planus.

In group I all lesions changed histologically and clinically to a normal mucosa or to a less affected tissue reaction. In group II this change was less pronounced, which suggests that the fillings themselves were not the only factor involved in the cause of these lesions. The results suggest that various etiologic factors are involved in lichenoid reactions and that the effect of removal of amalgam fillings cannot be predicted by epicutaneous patch testing and biopsies.