الفهرس 
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Abstract
The purpose of this study is to evaluate the effect of MDP containing resin cement and surface treatment of Translucent zirconia and Ultra translucent zirconia on shear bond strength.
Eighty zirconia discs were constructed with standerdized dimensions for this study. Samples were divided into two groups according to type of zirconia material that have been used: group I: Translucent zirconia samples (n=20) group II: Ultra translucent zirconia samples (n=20) Each group will be subdivided into 2 subgroups according to the surface treatment Subgroup A: Samples will be treated with air abrasion Sub group B: Samples will be left untreated. Each sub group will be further subdivided into 2 subgroups according to cement type: Subgroup A: samples cemented with MDP containing resin cement (Universal bond). Subgroup B: samples cemented with non MDP containing resin cement (Adper single bon II).
Rely x veneer cement has been applied to the free surface of zirconia samples then cured for 30 seconds. into the tube . then cement was light cured for 30 secondsby LEDcuring unit circumferentially at 650W/cm2 intensity according to manufacturer’s instructions.A computer controlled materials testing machine was used to test t shear bond strength to RelyX veneer resin cement, compared with the control. Finally, deboneded samples were examined under the scan electron microscope to determine their mode of failure.
Numerical data were explored for normality by checking the data distribution, calculating the mean and median values and using Kolmogorov-Smirnov and Shapiro-Wilk tests. Data showed parametric distribution so; it was represented by mean and standard deviation (SD) values. Three-way ANOVA was used to study the effect of different tested variables and their interaction on shear bond strength. Independent t-test was used to analyze simple main effects. The significance level was set at P ≤0.05 for all tests.
The results showed thatTranslucent zirconia has higher shear bond strength Ultra translucent zirconia.
Regarding the effect of ceramic material and resin cement For MDP containing resin cement, translucent zirconia had a significantly higher (mean±SD) value than ultra translucent zirconia. While for Non-MDP containing resin cement there was no significant difference between both materials.
Regarding the effect of surface treatment and resin cement for treated and untreated samples, MDP containing resin cement had a significantly higher (mean±SD) value than Non-MDP containing resin cement.
Regarding the effect of ceramic material and surface treatment. Ultra translucent zirconia with air abrasion containing value is non significantly higher than Ultra translucent zirconia untreated containing value. For both surface treatments, translucent zirconia had a non significantly higher (mean±SD) value than ultra translucent zirconia.
Conclusion:
According to the limitations of this study, the following conclusions were drawn:
1- Both surface topography and shear bond strength value of ceramic systems are affected by the type of material and surface treatment performed.
2- Sandblasting with 50-µm alumina particles positively enhance shear bond strength than no surface treatments methods for both materials
3- MDP containing resin cement showed higher shear bond strength than non-MDP containing resin cement.
Clinical Recommendation:
Under critical clinical situations, selection of the bonding mechanism should be focused on two important points: high initial bond strength value and long term bond strength between zirconia resin interface. Also, the use of phosphate monomer luting cements on freshly air-abraded zirconia as the simplest and most effective way for zirconia cementation procedure today.