[Determining the threshold level for sensibility responses to galvanic potentials in the oral cavity]

The presence of different alloys in the oral cavity may produce potential differences of up to 900 mV. In the majority of the patients this phenomenon presents no problems. Occasionally, however, disturbing sensations, such as "metallic taste", "twinging or stabbing" and "minute electric shock" are reported. In finding out on the threshold level for discomforting sensations due to galvanic potentials in different probands, a special battery operated device was developed. Using a pair of electrodes connected to metallic restorations in the mouth, this device enabled the application and adjustment of direct current voltage and a superimposed pulse spectrum to evoke sensible reactions. The trials were conducted with 102 probands. The mean value for the threshold of sensation was above 1000 mV. In solitary cases, however, the threshold level was as low as 250 mV. This method may be used as a diagnostic aid to the objective assessment of complaints due to galvanic effects in the oral cavity and for the selection of a suitable metal in sensitive patients.