Dental amalgam contains 50% mercury, copper, silver and tin. These metals bathed in acid saliva form a battery. Experience collaborating with a mercury-free dentist indicates that the metallic dental fillings most urgently needing replacement are those with the highest associated voltages (>100mVs). Electrical curre nts caused by mercury amalgam dental fillings are liable to be associated with chronic illness, and replacing them with non-metallic, non-toxic dental material can be therapeutic. An ea rthing mat (9) that removes static electricity from patients with high-voltage mercury amalgam dental fillings can cause symptomatic relief. Two clinical cases are presented as evidence of the concept.