The matrix phase of a ductile dental amalgam

In this study, the ternary HgAgSn-_γ1 matrix of a ductile dental amalgam has been characterized and compared with that of a brittle amalgam. Specimens of both amalgams were prepared form commercial alloy powders according to the ADA specification 1, stored at 37°C and studied by differential scanning calorimetry technique at timed intervals up to 1 year. Experimental amalgams of AgCu eutectic admixed with varying concentrations of Sn were used as standards. The matrix of the ductile amalgam was found to contain two substructures initially. One was saturated with Sn and the other contained lesser amounts of Sn. These substructures disappeared with time leading to a matrix in which Sn was well below its saturation limit but uniformly distributed. The matrix of the brittle amalgam, on the other hand, was saturated with Sn during the entire period of this study.