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

Purpose: The aim of the present study was to evaluate the shear bond strength of different core materials (composite resin, resin modified glass ionmer and all ceramic) with two cement types (adhesive resin and resin modified glass ionomer). Scanning electron microscope testing was also carried out to assess the mode of failure. Materials and Methods:total of 80 disc shaped samples were constructed, 60 from three nonmetallic core materials (composite resin, resin modified glass ionomer and all ceramic) 20 samples of each type. Another 20 samples were prepared from dentin as a control group. Samples of core materials were constructed as discs of 7 mm in diameter and 4 mm in thickness with a surface area of 38.46 mm2, then each two discs from the same material were cemented together to test the bond strength with the luting cements ) adhesive resin cement ,resin modified glass ionomer cement) in between. All samples subjected to thermo-cycling and then all samples were individually and vertically mounted on a computer controlled materials testing machine. Results:For adhesive resin cement the results showed no statistically significant difference between (Composite core with resin cement) and (Ceramic core with resin cement); both showed the statistically significantly highest mean shear bond strength,For resin modified glass ionomer cement the results showed no statistically significant difference between (RMGI core with RMGI cement) and (Dentin core with RMGI cement); both showed the statistically significantly highest mean shear bond strength. Results of scanning electron microscope showed that all tested core-cement combinations showed Mixed type of failure (Adhesive/cohesive) except in (composite discs/RMGI cement) and (ceramic discs/RMGI cement) which experienced adhesive type of failure

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