In vitro bonding of prosthodontic adhesives to dental alloys.

In vitro tensile bond strengths were determined for three adhesive cements and two resin-bonded bridge cements to two alloys, each prepared by two methods: sandblasted Ni-Cr-Be alloy (I), electro-etched Ni-Cr-Be alloy (II), sandblasted Type IV gold alloy (III), and tin-plated Type IV gold alloy (IV). Storage conditions of 24 hours at 37 degrees C and 30 days at 70 degrees C were evaluated. The highest bond strengths were obtained for the electro-etched Ni-Cr-Be alloy, and all bond failures were cohesive. At both 24 hours and 30 days, the adhesive cements had the highest bond strengths to the other alloy/surface preparations (I, III, and IV). The adhesive cements usually failed cohesively under these conditions, whereas the resin-bonded bridge cements failed adhesively at the cement-alloy interface. Storage for 30 days at 70 degrees C caused average decreases of 30%, 5%, 15%, and 32% for alloy/surface preparations I to IV, respectively.