Oral mucosal lesions related to silver amalgam restorations.

A total of 49 consecutive patients with lesions of the oral mucosa that were in contact with corroding dental amalgam restorations were subdivided into two groups. In group 1 the lesions were restricted to the contact area opposing the dental restoration, whereas the extent of the lesions in group 2 exceeded that of the contact area. Epicutaneous test for mercury allergy showed that a significantly greater proportion of the patients in group 1 had positive reactions to mercury than in group 2 (p = 0.019). The amalgam restorations were replaced by composite resin or porcelain fused to gold crowns, or contact between amalgam fillings and oral mucosa was prevented by an acrylic splint. After this treatment regression of lesions was far more pronounced in group 1 than in group 2 (p less than 0.001). On the basis of these findings, contact allergy to mercury is suggested as a possible etiologic factor of the mucosal changes in group 1, and the designation contact lesion is proposed for such lesions. The lesions of patients in group 2 seem unrelated to a contact allergy to mercury, and other causes such as lichen planus should be considered.