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The effect of different sodium chloride concentrations on the integrated currents (charge transfers) between dental amalgams and a gold alloy was studied in a bimetallic cell containing saliva or saline solutions. The integrated currents were only to a minor degree affected by increasing chloride concentrations for the high copper amalgams both in saliva and saline solutions. The integrated currents in the experiments involving conventional amalgam were several times higher than those for high copper amalgams. In saline solutions a charge transfer maximum was found at 0.2 M chloride. In saliva an increase of the charge transfer was found with increasing chloride content.

The galvanic currents between amalgam and gold alloy electrodes were higher in saline solutions than in saliva. Conventional amalgam supported higher currents than high copper amalgams when short-circuited with a gold alloy. The galvanic currents were not affected or affected only to a very small degree when whole saliva from different persons were compared. Higher currents were recorded when short-circuiting conventional amalgam and gold alloy electrodes using parotid saliva than when using whole saliva collected from one person. However, removing molecules with a molecular weight higher than 10(4) from whole and parotid saliva did not seem to affect the galvanic currents.

Short-circuited electrodes of dental amalgams and a gold alloy were used in an attempt to study a possible relationship between the quantity of copper and tin ions released into an electrolyte and the charge transferred between the electrodes. It was found that under the experimental conditions used the quantity of tin ions released was related to the charge transferred between the conventional amalgam and the gold alloy. The same tendency was found using a saliva sample which confined and collected the released tin ions into a small volume when the conventional amalgam specimen was short-circuited to the gold alloy specimen in vivo.

The purpose of this investigation was to study the tarnish and corrosion of three commercial copper alloys, three experimental copper alloys, two nickel alloys, and one high-gold alloy by exposing the specimens for four weeks to artificial saliva and saline solutions. Half of the specimens were brushed, and the solutions were changed regularly. The copper-based and the beryllium-containing nickel alloys exhibited significant surface alterations after exposure to either solution. The potential of elevated release of ions to the oral cavity and to the target organs by some of the investigated alloys should be considered if dental usage of these alloys is to be extended.