Reactions of the oral mucosa related to silver amalgam: a review

Lesions of the oral mucosa caused by amalgam restorations are rare. They may be due to Type IV contact hypersensitivity or toxic reactions to products generated by the restorations. Hypersensitivity reactions to amalgam seem to be related to mercury in almost all cases. The basis for requiring allergologic examination of patients suspected of contact hypersensitivity to amalgam is the presence of whitish or reddish, sometimes ulcerative oral mucosal lesions with a clear anatomic relation to amalgam fillings. The clinical features of lesions due to toxic reactions from amalgam restorations do not differ from those of lesions due to contact hypersensitivity, and the diagnosis is obtained by exclusion based on a negative patch test. Amalgam accidentally implanted in the oral mucosa results in amalgam tattoos which are flat lesions of bluish, blackish or slate grey color. Implanted amalgam does not produce an acute tissue response and need not be removed except for diagnostic reasons.