INTRODUCTION: The aim of this study was to evaluate the shear bond strength between a Ni-Cr alloy and a ceramic system submitted or not to thermocycling. MATERIALS AND METHODS:Forty-eight cylinder blocks of Ni-Cr with 3.0 mm diameter by 4.0 mm hight and 48 disc-shaped specimens (7.0 mm in diameter by 2.0 mm thick) composed of ceramic were prepared. The Ni-Cr cylinder blocks were randomised in two groups of 24 specimens each. One group was submitted to air-particle abrasion (sandblasting) with 50 μm Al(2)O(3) (0.4-0.7 MPa) during 20 s, and the other group was submitted to mechanical retentions with carbide burrs. Each group was subdivided into other two groups (n = 12), submitted or not to thermocycling (500 cycles, 5-55°C). The cylinder blocks were bonded to the disc-shaped ceramic specimens under 10 N of load. The shear bond strengths (MPa) were measured using a universal testing machine at a cross head speed of 0.5 mm/min and 200 kgf of load. The data were submitted to statistical analysis (anova and Tukey's test). RESULTS: The air-particle abrasion group exhibited significantly higher shear bond strength when compared to drilled group (p < 0.05). CONCLUSIONS: Thermocycling decreased significantly the bond strengths for all groups tested.
RCT Entities:
INTRODUCTION: The aim of this study was to evaluate the shear bond strength between a Ni-Cr alloy and a ceramic system submitted or not to thermocycling. MATERIALS AND METHODS: Forty-eight cylinder blocks of Ni-Cr with 3.0 mm diameter by 4.0 mm hight and 48 disc-shaped specimens (7.0 mm in diameter by 2.0 mm thick) composed of ceramic were prepared. The Ni-Cr cylinder blocks were randomised in two groups of 24 specimens each. One group was submitted to air-particle abrasion (sandblasting) with 50 μm Al(2)O(3) (0.4-0.7 MPa) during 20 s, and the other group was submitted to mechanical retentions with carbide burrs. Each group was subdivided into other two groups (n = 12), submitted or not to thermocycling (500 cycles, 5-55°C). The cylinder blocks were bonded to the disc-shaped ceramic specimens under 10 N of load. The shear bond strengths (MPa) were measured using a universal testing machine at a cross head speed of 0.5 mm/min and 200 kgf of load. The data were submitted to statistical analysis (anova and Tukey's test). RESULTS: The air-particle abrasion group exhibited significantly higher shear bond strength when compared to drilled group (p < 0.05). CONCLUSIONS: Thermocycling decreased significantly the bond strengths for all groups tested.