Effect of investment on casting high-fusing alloys.

A definite interaction in castability was found between the three different phosphate-bonded investments and four different alloys tested in this study. 1. Casting completeness of all alloys, as measured by the length of test specimens, was affected by the investment. The high-gold content alloy, SMG II, yielded the most complete castings of all combinations teted when invested with Ceramigold. Of the nonprecious alloys, Biobond CB combined with Ceramigold II resulted in the longest samples. 2. The surface quality of Jelbon and SMG II castings was good, regardless of the investment used. Wiron S and Biobond CB varied in surface quality with different investments, Ceramigold II giving the smoothest castings. 3. All alloys, especially the nonprecious ones, should be tested for compatability with different investments before asserting their qualities or lack of qualities for clinical use.