الفهرس 
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Abstract
Objective: The aim of the present study is to evaluate the effect of two surface treatments (acid etching and sandblasting) on the shear bond strength of composite resin cement to pressed and repressed lithium di silicate ceramics. Patients and Methods: Fifty two lithium disilicate discs were constructed of 10mm diameter and 2mm thickness and were divided into 2 groups. group (P) composed of 26 discs constructed from newly introduced lithium disilicate ingots while group (R) composed of 26 discs constructed from left over material that was shaped to resemble an ingot. Results: The discs were thermo-cycled in an attempt to simulate the intra-oral conditions and its detrimental effect on bond strength for 5,000 cycles which is equivalent to 6 months of intra-oral service and then the shear bond strength test was initiated. Then the mode of failure was examined and all data were collected, tabulated and statistically analyzed to detect any significant values among the tested groups. Conclusion: The re-use of e.max press left over buttons for construction of all ceramic restoration could be considered for socio-economic reasons. The type of surface treatment adopted greatly affects the shear bond strength of pressed and repressed ceramics and hence the durability of resin cement bonded to ceramics.
Sandblasting cannot be considered as a reliable surface treatment when bonding to pressed and repressed glass ceramic.