Effect of admixed indium on properties of a dispersed-phase high-copper dental amalgam

A new dental amalgam alloy containing admixed indium is available for clinical use. The purpose of this study was to conduct a full range of laboratory tests on two alloys containing differing amounts of admixed indium and on a similar alloy that did not contain indium. Results showed that less mercury was required to mix the alloys containing indium since admixed indium promotes wetting of the alloy. Back-scattered electron images showed the Ag-Hg matrix to be in good apposition to the Ag-Sn particles and to the Ag-Cu eutectic spheres, and there was no evidence of unreacted indium. The alloys containing admixed indium demonstrated improved resistance to creep and very little dimensional change upon setting. The early compressive strength was low for the alloys containing indium, but compressive strengths were significantly higher than those of the alloy without indium at 24 h and 7 d. Some improvement in resistance to marginal leakage and to corrosion was shown for the alloys containing indium.