Demonstration of a possible source of error with an electric pulp tester

The purpose of this study was to determine whether electrical current can travel between adjacent teeth through contacting interproximal amalgam restorations. Twenty-two extracted human premolars were restored with class II amalgam restorations. They were then mounted in pairs in self-curing resin, simulating adjacent teeth. Only their restorations were allowed to contact. An electrical multimeter was used to supply electrical current and to measure any current passing through the mounted teeth. One current measurement was made from the buccal enamel of a tooth to the occlusal surface of the filling in that tooth. A second measurement was made from the buccal enamel of the same tooth to the occlusal surface of the adjacent filling. These two measurements were made for all 11 trials. Statistically, all current that entered the first tooth passed to the adjacent tooth. This finding suggests a potential source of error when using an electric pulp tester.