الفهرس 
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Abstract
Purpose: The purpose of this in-vitro study is to investigate the effect of intaglio surface conditioning on the fracture strength of veneered zirconia crowns compared to full-contour zirconia crowns. Material and methods: Thirty two human maxillary premolars were prepared for zirconia all-ceramic crown with the following preparation criteria: 6-degree axial taper, 1-mm shoulder finish line, 2-mm occlusal reduction and occluso-gingival height of 5 mm. All specimens were divided into two groups (n=16) for each ceramic material. In the first group all prepared premolars restored by full contour zirconia crowns fabricated (KATANA Zirconia blocks) by manual aided design/ manual aided manufacture (MAD/MAM), while in second group all teeth restored by veneered zirconia crowns. The cores were directly fabricated (VITA In-Ceram YZ blocks) by (MAD/MAM) and build-up by veneering ceramic. Each main group was subdivided into two subgroups (n=8). Crowns of first subgroup were sandblasted with 50μm Al2O3 while the second subgroup was remain as milled. All specimens were luted using self adhesive resin cement (Multilink speed). Finally all specimens were loaded in a universal testing machine with the compressive load (N) applied along axis of the specimen. Fracture load was recorded for each specimen. Statistical analysis was done using the kruskal-wallis test followed by Mann-whitney tests. Results: The fracture resistance records high significance difference between veneered zirconia and full-contour zirconia (P=0 for both tests) irrespective to the type of surface treatment. Contrary, both tests proved that the surface treatment has no significance effect on fracture resistance irrespective to the type of material (P=0.72). Conclusion: Within the limitation of this in vitro study, full-contour zirconia crowns showed higher fracture resistance than veneered zirconia crowns. On the other hand surface treatment (sandblasting) has no significance effect on the fracture resistance.