الفهرس 
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Abstract
Evaluate the influence of zirconia ceramic chemical etching using Ammonium hydrogen difluoride on the bond strength at zirconia/resin cement interface with or without primer application. Materials and methods: A total of 48 zirconia discs (8mm × 3mm) were fabricated with CAD/CAM. All discs were air-borne particle abraded using 50 µm Al2O3 particles then divided into three equal groups (n=16); (1) Air-borne particle abrasion (AB) control group; (2) Ammonium hydrogen difluoride (AHD) group; (3) Silica coating (SC) group. Each main group was subdivided into two equal subgroups (n=8) according to primer application (Monobond®N) (P) or no primer application (NP). Composite resin discs (Nexcomp®) were cemented to the treated zirconia discs using adhesive resin cement (Multilink®N). All bonded specimens were stored in water bath for 6 months and subjected to 10,000 thermal cycles. Shear bond strength (SBS) test was performed afterwards using a universal testing machine. Scanning Electron Microscope was used for failure mode examination. Results: The statistical analyses were done using two-way ANOVA and serial one way ANOVAs followed by Post Hoc Tukey-HSD test at (α = 0.05). Application of multi-purpose primer significantly increased SBS values compared to no primer application (p= 0.0001). The highest mean SBS (MPa) was reported for group ABP (10.5±1.3MPa), followed by AHDP group (9.1±1.0MPa). While the lowest mean SBS value was observed for group SCNP (3.4±1.5MPa).There was statistically significant difference between AB with primer (ABP) group and all other groups (p≤ 0.001) except for AHD with primer (AHDP) group (p= 0.261).
Conclusions: Ammonium hydrogen difluoride etching is an effective surface treatment method for zirconia ceramic with comparable results to air-borne particle abrasion. Universal primer is an important factor for long-term bond strength between zirconia ceramic and resin cement.