Thesis (M.Sc.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Prosthodontics

The aim of the study was to assess the effect of different bonding approaches [4th generation total etch, the new 8thgeneration self etch and self adhesive resin cements] on the shear bond strength to enamel and dentine. Scanning electron microscopic evaluation is carried out to study the mode of failure at the bonding interface. A total of thirty freshly extracted human molars were selected for the current study each was embedded in acrylic resin blocks. The buccal and lingual surfaces were ground flat to expose enamel and dentin using Isomet 4000 linear precision saw. A total of sixty composite resin discs were fabricated and cemented using Resin cement employing total etch bonding approach (4th generation bonding agent) [Syntac + Variolink®II] ,self adhesive approach [RelyX{u2122} UnicemAplicap{u2122}] and self etch bonding approach (8th generation bonding agent) [futurabond DC + Bifix QM]. Shear bond strength test was carried out to enamel and dentin and dentin samples. Results were statistically analyzed. Mode of failure was inspected using environmental scanning electron microscope. In Enamel, It was found that 4th generation total etch bonding approach recorded highest shear bond strength mean value followed by 8th generation self etch bonding approach and were statistically insignificant; whereas self adhesive bonding approach recorded statistically significant lowest shear bond strength mean value. In dentin, It was found that 4th generation total etch bonding approach recorded statistically significant highest shear bond strength mean value followed by 8th generation self etch bonding approach; whereas self adhesive approach recorded statistically significant lowest shear bond strength mean value. Within the limitations of this study, it was concluded that upon bonding to enamel, the new 8th generation self etch bonding approach combines the advantage of a simplified bonding procedure with high shear bond strength values

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