Abstract
BackgroundTo evaluate shear bond strength of zirconia to composite resin using different universal and conventional adhesives and a zirconia primer.Material and MethodsForty zirconia blocks were fabricated of zirconium ingots (10×10×5 mm) and sintered at 1530°C for 2 hours. They were then air-abraded with Al2O3 particles. The specimens were divided into 4 groups and subjected to one of the following bonding agents: Futurabond U (group 1), Clearfil Universal Bond, universal adhesives (group 2), Z-Prime Plus, zirconia primer (group 3) and Adper Single Bond 2, conventional adhesive (group 4). Composite resin was then applied in a diameter of 5 mm and in a thickness of 2 mm. All the specimens were stored in distilled water at 37°C for 24 hours and then thermocycled between 5°C and 55°C for 5000 cycles with a 30-second dwell time. The shear bond strength was then evaluated with a universal testing machine at a crosshead speed of 1 mm/min. Data (MPa) were analyzed using ANOVA and LSD test (P≤0.05). The specimens were evaluated under a stereomicroscope to determine the mode of failure.ResultsThe mean shear bond strength was 16,874 MPa in group I, 13.4434 MPa in group II, 11.6500 MPa in group III and 6.8700 MPa in group IV. ANOVA revealed that the shear bond strength in group IV was significantly lower than that in other groups (P≤0.05).ConclusionsThe shear bond strength in group I was significantly higher than that in groups III and IV. So Universal adhesives could provide higher shear bond strength of zirconia to composite resin after thermocycling compared to zirconia primers. Key words:10-MDP, shear bond strength, universal adhesive systems, zirconia primer.
Highlights
Use of zirconia is on the increase in modern dentistry due to its superior biocompatibility and favorable mechanical properties [1]
Zirconia is usually used as a core for restorations due to the high opacity of zirconia ceramic so that a proper esthetic appearance can be achieved; subsequently the core is veneered with the use of feldspathic ceramic [2]
Feldspathic ceramics are etched with the use of hydrofluoric acid and the chemical bond to composite resin improves by applying silane to the etched surface [8]
Summary
Use of zirconia is on the increase in modern dentistry due to its superior biocompatibility and favorable mechanical properties [1]. Universal adhesives are a new group of adhesives that, based on manufacturer’s claim, have the capacity to be used with all the techniques, including total etch, selective and self-etch and can bond to all the direct substrates such as enamel and dentin and indirect substrates such as metals, zirconia and glass ceramics, in one product These adhesives, too, contain MDP monomer, which explains their etching capacity in association with their bond strength to the substrates mentioned above [16]. The aim of the present study was to evaluate the effect of one zirconia primer, Z-Prime, and two universal adhesives, Clearfil Universal Futura Bond U (containing MDP) and Adper Single Bond 2 (without MDP monomer and only for evaluating the effect of wetting) on the shear bond strength of composite resin to zirconia under the same surface preparation conditions. Universal adhesives could provide higher shear bond strength of zirconia to composite resin after thermocycling compared to zirconia primers
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