The microstructure of corroded amalgams.
One conventional amalgam and two amalgams with a high copper content were stored in 0.9% NaCl solution buffered with phosphate to pH 6. In one experimental series the amalgams were placed in contact with a gold alloy. Every 7 weeks the solutions were changed and analyzed with regard to elements released from the amalgams. The microstructure of the specimens was studied in a scanning electron microscope before immersion and after 7 and 35 weeks in the solution. All the amalgams corroded along the grain boundaries in the gamma 1 phase. Corrosion was greatest in the gamma 2 phase of ANA 68, in the eta phase of ANA 2000 and in the reaction zone (eta + gamma 1) surrounding the Ag-Cu-eutectic particles of Dispersalloy. The microstructure of the corroded amalgams showed similarities to amalgams corroded in vivo. The change in microstructure observed in cross-sections of the corroded specimens was related to the amounts of corrosion products released into the saline solution.
D003300:Copper; D003343:Corrosion; D003722:Dental Alloys; D003723:Dental Amalgam; D006047:Gold Alloys; D006863:Hydrogen-Ion Concentration; D012965:Sodium Chloride; D013499:Surface Properties; D013997:Time Factors
D003722:Dental Alloys; D006047:Gold Alloys; C033470:Dispersalloy; D012965:Sodium Chloride; C047094:ANA 68; D003300:Copper; D003723:Dental Amalgam; C047093:ANA 2000