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

This study was designed to investigate the effect of bleaching on the bond strength of ceramic laminate veneers using two adhesive resin cements (rely x ultimate and variolink N ) as well as, the time elapsed between bleaching & bonding on the shear bond strength of laminate veneers bonded to bleached enamel.Thirty recently extracted maxillary central incisors (free of caries, fracture, or cracks) were selected, teeth were prepared to accommodate E max veneer discs of equal thickness .IPS e.max ingots were used to fabricate 30 ceramic discs with standardized dimensions following the manufacturer{u2019}s recommendations. (5mm diameter x 1 mm thickness).Samples grouping:-The E max discs were divided into 6 groups according to the time elapsed between bleaching and bonding (Table 2): *Group1 ( n=5 ): in which E max discs were bonded to the prepared (non-bleached ) tooth surface by using Variolink N resin cement .Group 2 (n=5): in which E max discs were bonded to the prepared ( non-bleached ) tooth surface by using Rely X Ultimate resin cement .Group 3 ( n=5) : in which E max discs were bonded to the prepared ( bleached ) tooth surface immediately after bleaching by using Variolink N resin cement . *Group 4 ( n=5) : in which E max discs were bonded to the prepared (bleached) tooth surface immediately after bleaching by using Rely X Ultimate resin cement .Group 5 (n=5) : in which E max discs were bonded to the prepared ( bleached ) tooth surface 2 weeks after bleaching by using Variolink N resin cement .Group 6 (n=5) : in which E max discs were bonded to the prepared ( bleached ) tooth surface 2 weeks after bleaching by using Rely X Ultimate resin cement .All samples were tested using a universal testing machineat cross-head speed of 0.5 mm/min until failure. The force required to fracture each crown was measured in Newton's

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