Recurrent contact dermatitis caused by mercury in amalgam dental fillings

A metal worker had repeated episodes of contact dermatitis over a period of years. Patch tests with 5% ammoniated mercury were strongly positive but occupational contact could not be proved. Recurrence of the dermatitis one day after amalgam dental fillings had been made and again one year later, this time without new fillings, raised the possibility that it was due to the old amalgam fillings. Removal of all the amalgam fillings resulted in a new outbreak of severe dermatitis; during the 5 years ensuing there has been no recurrence. This case history suggests that contact dermatitis may be caused by not only the mercury in new fillings but also by that in old fillings.