Effect of material and configuration of antagonist on combined wear.

The aim of this study was to investigate the effect of antagonist material and configuration on combined wear, which was produced by alternating toothbrush wear and simulated occlusal wear on one specimen. Worn volume and maximum worn depth comparisons were done using two antagonist materials (steel and ceramic) and two antagonist configurations (flat and round). For the material factor, worn volume by the ceramic antagonist was greater than that by steel antagonist in the combined wear test.

Development of casting investment preventing blackening of noble metal alloys Part 2. Application of developed investment for type 4 gold alloy.

The objective of this study was to evaluate the efficacy of the developed investment for the prevention of blackening of a cast Type 4 gold and to analyze the oxides on its surface in relation to the blackening of the alloy. The experimental investments were prepared using a gypsum-bonded investment in which boron (B) or aluminum (Al) was added as a reducing agent. A Type 4 gold alloy was cast into the mold made of the prepared investment.