Relationship between sandblasting and composite resin-alloy bond strength by a silica coating.

Modification of alloys for resin-bonded fixed partial dentures has been suspect since the introduction of the conservative procedure. This study investigated the effect of sandblasting on composite resin-alloy bond strengths with the Silicoating technique. Ag-Pd and Ni-Cr alloys were prepared for casting. The specimens then were sandblasted with 37 microns or 250 microns Al2O3 particles under the following conditions: 3 kg/cm2 for 30 seconds; 5 kg/cm2 for 10 seconds, 30 seconds, and 45 seconds; and 7 kg/cm2 for 30 seconds. After each sandblasting treatment, the surfaces of the alloys were examined with the scanning electron microscope and the wettability of the alloy surfaces was measured. After sandblasting, the alloy surface was silica-coated, and light-cured composite resin then was bonded to the alloy. Specimens were divided, stored in dry air for 1 week, and thermocycled from 4 degrees to 60 degrees C for 10(4) cycles. Bond strength was measured by applying compressive shear stress. It was found that sandblasting made the alloy-water contact angle smaller and wettability greater. The adhesive strength of composite resins with alloys was influenced by sandblasting.