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Thermocycling Effects on Resin Bond to Silicatized and Silanized Zirconia

Various techniques have been introduced to create a durable resin composite bond to sintered zirconia (Y-TZP). Shear bond strength values achieved through tribochemical treatment have been investigated in numerous studies, but less is reported about long-term durability. The objective here was to evaluate the effects of thermocycling and silane on shear bond strength of a composite luting cement to silicatized Y-TZP. Two groups of Y-TZP (Procera Zirconia, Nobel Biocare), both consisting of 40 specimens were prepared. The specimen surfaces were air particle abraded with silica-coated aluminum trioxide particles (particle size 110 μm, duration 15 s, air pressure 300 kPa, nozzle distance 10 mm). The silica-coated surfaces in group ZA were silanized with an acrylate-functional silane (Experimental laboratory-made acrylate silane, Toray Dow Corning Silicone) and in the other group ZM with a pre-activated methacrylate silane (ESPE Sil, 3M ESPE). The surfaces were coated with adhesive system (Scotchbond 1, 3M ESPE) and photo-polymerized for 10 s. Resin composite luting cement (RelyX ARC, 3M ESPE) stubs were bonded to substrates and photo-polymerized for 40 s. The test specimens were thermocycled for 0, 1000, 3000, 8000 or 15 000 times (temperature 5–55°C, exposure time 20 s). The shear bond strengths of luting cement to ceramics were measured with a crosshead speed of 1.0 mm/min. ANOVA was used for statistical analysis. ANOVA revealed that both silane and thermocycling affected significantly (p < 0.001) the shear bond strength. Short term hydrolytic stability of acrylate silane was superior. It was concluded that evaluation of bonding requires extended thermocycling.