الفهرس 
Marginal accuracy of CAD-CAM monolithic zirconia and lithium disilicate crowns
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Abstract
The current study evaluated the marginal gap width of recently introduced monolithic high translucent zirconia crowns compared to Ips e.max CAD crowns with deep chamfer finish line with two different thickness. A total of thirty-two (n=32) crown samples were constructed from monolithic highly translucent zirconia (n=16) and Ips e.max CAD (n=16) using CAD/CAM system on specially designed stainless die representing an all ceramic crown preparation for maxillary central anterior tooth.These dies were machined in a standardized manner using an engineering lathe machine (6mm inciso-gingival height, 120 total incisal convergence) The preparation ended with either: 1-0.8mm deep chamfer finish line. Or 1.1mm deep chamfer finish line. The crown samples were divided into two equal groups: group I: (n=16) monolithic highly translucent zirconia (Bruxzir anterior, glidwell) group II: (n=16) lithium disilicate glass ceramic (Ips emax CAD, ivoclare vivadent) Each group was subdivided into two equal subgroups: Subgroup I: (n=8) deep chamfer finish line with 0.8 mm thickness Subgroup II: (n=8) deep chamfer finish line with 1mm thickness Each of the stainless-steel dies was powder sprayed with telescan spray then scanned by the identica scanner which showed a three-dimensional virtual image of the scanned die on the screen. Using EXOCAD software, a virtual die appeared on the screen to start the designing step