Effect of metal surface treatment on ceramic bond strength.

This study indicates that the unaltered specimens of both alloys produced the lowest bond values; for the gold-palladium alloy, a short degassing period (manufacturer's recommendation) and a 10-minute degassing period resulted in significantly lower bond strengths than those observed with the aluminum oxide and the steam cleaning treatments; and all treatments of the silver-palladium alloy gave comparable bond strengths to that obtained with the manufacturer's recommendation for surface treatment. Because the simplified methods gave equivalent or higher bond strength values than the manufacturer's recommendations, and because of the time saving, we recommend the following procedures for the porcelain-alloy systems tested: After casting and investment removal, use an abrasive to remove casting irregularities and to modify or correct the surface that will receive porcelain. Create a uniform matte finish on the surface that is to receive porcelain by pressure blasting with 50 micron aluminum oxide particles, or steam clean the surface for 30 seconds, or both. Proceed with opaquing.