الفهرس 
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Abstract
Aim: Is to evaluate the Shear bond strength of bioactive cement (Ceramir® Crown & Bridge (C&B)) on hybrid ceramic CAD/CAM restoration compared to self-adhesive resin cement.
Methodology:o A total of fourteen specimens were prepared from Cerasmart CAD/CAM block A2 shade and cut in square shape (14X12X1.5) mm by low speed diamond saw isomet 4000 with water coolant.
o One surface of all the specimens will be treated by sandblasting using 50 microns aluminum-oxide powder according to the manufacturer‟s instructions for the respective ceramic block material.
o Each Cerasmart specimen received one resin cylinder Irise of polyethylene tube having 2.5 mm diameter and 1.5 mm height were positioned over the plate surface and filled with cement, creating cement cylinder having the same dimensions .o half of these specimen cemented by self adhesive resin (RelyXUnicem) dental luting cement and the rest cemented by bioactive ( ceramir ) dental cement.
o Polyethylene irises were removed after 24 hours to ensure a complete polymerization of the dual- cured resin cement.o finally ,the sample will be tested for shear bond strength using universal machine, Shearing test was done by compressive mode of load applied at ceramic-cement interface using a mono-bevelled chisel shaped metallic rod attached to the upper movable compartment of universal testing machine traveling at cross-head speed of 0.5 mm/min. The load required to debonding was recorded in Newton.
Results: It was found that the shear bond strength mean±SD values recorded for resin group were (7.537±2.46MPa) with minimum value (4.149MPa) and maximum value (11.049MPa).
Meanwhile the shear bond strength mean±SD values recorded for CSC group were (2.529 ± 0.512MPa) with minimum value (1.892MPa) and maximum value (4.001MPa).the Failure mode It was found that resin group recorded statistically significant (p=<0.0001<0.05) higher mean value (7.537±2.46MPa) than CSC group mean value (2.529 ± 0.512MPa) as indicated by unpaired t-test.
Conclusions:Within limitations of this study, the following conclusion and recommendations could be drawn as follows:1) self adhesive resin cement has higher shear bond strength to CAD-CAM hybrid ceramic (Cerasmart) compared to bioactive cement (ceramir)2) sand blasting of cerasmart ceramic provides acceptable bond strength when cemented by self adhesive resin cement3) the type of cement used with Cerasmart ceramic affect the shear bond strength with application of the same surface treatment.