Copper-, indium-, tin-, and calcium-fluoride admixed amalgams: release rates and selected properties

A conventional (Minimax), two single-particle high-Cu (Summalloy and Aristaloy CR), and two dispersed-phase (Cluster and Phasealloy) amalgam alloys were each admixed with 0.5 wt% of CuF2, InF3, SnF2, and CaF2, and evaluated for F-, Cu, and Sn release, as well as for corrosion resistance, microstructure, and compressive strength. Over a 43-week interval, only Cluster revealed somewhat of a sustained F- release in artificial saliva. A ranking for F- release was Cluster (highest), Summalloy, Phasealloy, Minimax, and Aristaloy CR. The effectiveness of the F- compounds in releasing F- followed CuF2 (highest), SnF2, InF3 (1.0%), InF3, and CaF2. Amalgams with admixed CuF2 released both the most Cu and increased Sn. For three amalgams, CaF2 admixtures also increased the Cu release. Constant-potential coulometry distinguished among the different fluoride amalgams. Only Minimax revealed a significant reduction in compressive strength with two admixtures. Microstructural analysis revealed an increased pore distribution around the Ag-Cu dispersed particles, and it was assumed that the F- particles were contained within the pores, since SEM, EDS with a low element detector, and ESCA were all unable to detect the F- particles.