[Studies on Pd base ternary alloys for dental amalgam. (Part 2) On the corrosion resistivity (author's transl)].

In the previous paper, the author reported the effect of composition of Pd base ternary alloys on the dimensional change, the compressive strength, hardness and microanalysis by EPMA. In this paper, corrosion resistivity of Pd base ternary alloy amalgam was studied by comparison of reflective light intensity, surface roughness and weight change before and after corosion test in 0.1% Na2S, 0.1% lactive acid and 1% NaCl solution. The main results obtained are as follows: (1) Pd base ternary alloy amalgam showed much higher corrosion resistivity than that of on the market silver-tin-copper amalgam. (2) On the (60 Pd-40 Ag)-Sn alloy amalgam, corrosion resistivity was gradually improved by addition of Sn up to 10 wt% Sn, and the best corrosion resistivity was observed in (60 Pd-40 Ag)-10 Sn among Pd base alloy amalgam tested in this study. (3) On the (60 Pd-40 Ag)-Cu alloy amalgam, corrosion resistivity decreased gradually with increment of Cu content. (4) Weight of (60 Pd-40 Ag)-Sn alloy amalgam was a little increased after corrosion test in 0.1% Na2S solution, but that of (60 Pd-40 Ag)-Cu alloy amalgam showed a tendancy to decrease. (5) Corrosion of Pd base alloy amalgam was observed mainly in the matrix. Tarnish on the core was observed a little. Since fine cut amalgam has the smaller rate of area of core than that of spherical amalgam, surface roughness was comparatively large.