Abstract
The aim of this study was to evaluate the effect of bleaching and thermocycling on microshear bond strength of bonded resin composites to enamel. Enamel slices were prepared from ninety-six intact human premolars and resin composite cylinders were bonded by using Adper Single Bond 2 + Filtek Z350 or Filtek silorane adhesive and resin composite. Each essential group was randomly subdivided to two subgroups: control and bleaching. In bleaching group, 35% hydrogen peroxide was applied on samples. Thermocycling procedure was conducted between 5°C and 55°C, for 3.000 cycles on the half of each subgroup specimen. Then microshear bond strength was tested. Methacrylate-based resin composite had higher bond strength than silorane-based one. The meyhacrylate-based group without bleaching along with thermocycling showed the most bond strength, while bleaching with 35% carbamide peroxide on silorane-based group without thermocycling showed the least microshear bond strength. Bleaching caused a significant degradation on shear bond strength of silorane-based resin composites that bonded using self-etch adhesive resin systems.
Highlights
Bleaching popularity and introducing the new bleaching products every year lead to many studies about the effects of these products on teeth and dental restorative materials
It has been stated that bond strength of restorations to enamel and dentin was affected by carbamide peroxide and this defect was related by carbamide peroxide concentration [4]
It was found that immediate postoperative bleaching with 20% carbamide peroxide gel, 6% hydrogen peroxide, and 19% percarbonate gel for 14 days had no influence on microleakage of Filtek composite bonded with Scotchbond 1 at the occlusal margins of the Class 1 restorations [10]
Summary
Bleaching popularity and introducing the new bleaching products every year lead to many studies about the effects of these products on teeth and dental restorative materials. It has been stated that bond strength of restorations to enamel and dentin was affected by carbamide peroxide and this defect was related by carbamide peroxide concentration [4]. The other studies showed increasing marginal leakage in postoperative bleaching of class V resin composite restorations [8, 9]. It was found that immediate postoperative bleaching with 20% carbamide peroxide gel, 6% hydrogen peroxide, and 19% percarbonate gel for 14 days had no influence on microleakage of Filtek composite bonded with Scotchbond 1 at the occlusal margins of the Class 1 restorations [10]. Composite materials may be failed by mechanical and thermocycling (TC) condition, interfacial debonding, microcracking, and filler particle fracture, International Journal of Biomaterials
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