الفهرس 
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Abstract
Objective: To evaluate the effect of different saliva cleaning protocols on the bond strength of resin cement to zirconia. Materials and methods: Sixty zirconia discs (8 mm diameter × 3 mm thickness) were fabricated by CAD-CAM technology. The bonding surface of zirconia discs was airborne-particle abraded with 50 µm Al2O3 particles at a pressure of 0.2 MPa for 10 sec and at a distance of 10 mm. All discs were randomly divided into six main study groups (n=10) according to the protocol of saliva cleaning; group 1 (NC): no artificial saliva contamination (control group), group 2 (PS): 10-MDP primer application followed by saliva contamination, group 3 (ES): ethyl cellulose (EC) coat application followed by saliva contamination, group 4 (SA): saliva contamination followed by airborne-particle abrasion, group 5 (SZ): saliva contamination then ZirClean® application, group 6 (SK): saliva contamination then KATANATM Cleaner application. Sixty resin composite discs (5 mm diameter × 2.5 mm thickness) were fabricated. They were cemented to zirconia discs using adhesive resin cement (Duo-Link UniversalTM). All specimens were stored in distilled water at 37 °C for 24 hours. Afterward, they were subjected to 10,000 cycles of thermocycling. The shear bond strength test (SBS) was performed using the Instron universal testing machine. SEM was employed to evaluate surface topography and failure modes. The results were tabulated and statistically analyzed using the one-way ANOVA test. The Post Hoc Tukey test was used for pairwise comparisons among different study groups. Results: Shear bond strength values revealed statistically significant differences (p=0.01) among the study groups. The highest mean shear bond strength was observed in the control group 1 (NC) (14.72±2.76 MPa), followed by group 4 (SA) (14.19±2.64 MPa), group 3 (ES) (14.12±2.58 MPa), group 6 (SK) (12.04±3.17 MPa), group 5 (SZ) (11.93±1.68 MPa), and the lowest was observed in group 2 (PS) (10.72±3.38 MPa). Post Hoc Tukey test showed a statistically significant difference between the control group 1 (NC) and group 2 (PS) (p = 0.002), between the control group 1 (NC) and group 5 (SZ) (p = 0.027), between the control group 1 (NC) and group 6 (SK) (p = 0.03), between group 2 (PS) and group 3 (ES) (p = 0.008) and between group 2 (PS) and group 4 (SA) (p = 0.007). Conclusions: Airborne-particle abrasion and EC coating were shown to be the best methods for cleaning and protecting the zirconia surface from contamination. Zirconia cleaners were also satisfactory alternatives for removing salivary contaminants. However, applying the 10-MDP primer before saliva contamination was not a sufficiently effective method, and therefore is not recommended.