Abstract:
The purpose of this study was to compare tensile bond strength between bonded and rebonded metal alloys to enamel and study the effect of different enamel surface treatments to improve tensile bond strength of rebonded metal alloys. One hundred and thirty-two bovine incisors were embedded in PVC tube using self-curing acrylic resin. Wax patterns were made and cast with base metal alloy. Teeth and metal specimens were flattened with 600-grit silicon carbide paper and metal specimens were sandblasted. Then, 66 metal specimens were cemented to the teeth with Superbond C&B and other 66 metal specimens with Panavia F2.0. The tensile bond strength was measured and mode of failure was analyzed. After debonding, visible cement was cleaned with ultrasonic scaler. Metal specimens were then sandblasted and specimens in each group of cement were divided into 6 groups of 11 each. Teeth in each group were treated with sandblasting, hydrogen peroxide with sodium ascorbate, ethyl acetate in acetone, methyl methacrylate, methyl formate-methyl acetate mixture and no treatment group. One specimen was randomly selected and inspected under SEM to determine the morphological change. Specimens were rebonded and tensile bond strength was tested and analyzed. In Superbond C&B group, high rebonding strengths were obtained when enamels were treated with sandblasting, methyl methacrylate and methyl formate- methyl acetate mixture group. In Panavia F2.0 group, no enamel surface treatments could improve rebonding strength. Combination of metal sandblasting and enamel treating with sandblasting, methyl methacrylate or methyl formate–methyl acetate mixture after Superbond C&B cementation could increase rebonding strength comparing with untreated enamel.
