Shear bond strength of porcelain-fused-to-alloys of varying noble metal contents.

The conclusions drawn from the present investigation are as follows: 1. The modification of waxing the metal rods prior to investing the baked porcelain disk in the dental stone eliminated the undesirable bond between the dental stone and the metal rod. The shear bond strengths obtained were believed to be true shear bond strengths. 2. Ceramo-metal restorations should be cooled at a slow rate, so that the alloy and the porcelain have approximately the same cooling rate. 3. Shear bond strengths developed in porcelain-metal composites were in descending order for Biobond, Vita, and Ceramco porcelain. 4. Push-test shear bond strengths were always higher than pull-test shear bond strengths. Both push- and pull-tests seemed to be equally valid for evaluating bond strengths in porcelain-metal composites. 5. The porcelain-metal composite of the silver-free gold alloy showed higher shear bond strengths for all porcelains.