Electrical potentials of restorations in subjects without oral complaints

The electrical potentials of 183 amalgam and 11 precious metal restorations, and one set of brackets, were measured. None of the 28 subjects had galvanism, leukoplakia, oral lichen planus, or toxic or allergic reactions to restorations. The potentials of the amalgam restorations increased with age, from about -350 mV NHE at 30 days, to about +100 mV NHE after more than 1000 days. In most subjects potential differences of more than 50 mV were present between restorations; this phenomenon is therefore assumed to be common in healthy populations.