الفهرس 
Assessment of fractureresistance of VITA suprinity crownsversus IPS E.max CAD crowns : In vitro study
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Abstract
This study was conducted to assess the fracture resistance of lithium disilicate (IPS E.max CAD) crowns compared to zirconia reinforced lithium silicate (VITA SUPRINITY) ones. According to the sample size calculation, a total of twenty crowns were constructed. The samples were divided into two equal groups, ten samples each according to the type of material used: i. group (E): Ten crown samples (n=10) fabricated of IPS E.max CAD. ii. group (S): Ten crown samples (n=10) fabricated of VITA SUPRINITY. A stainless steel die was custom made to simulate a tooth preparation for a ceramic crown of a mandibular first molar, 6-mm occluso-gingival, 8-mm cervical diameter, 6mm occlusal diameter and a total occlusal convergence of 16o with a circumferential 1mm shoulder finish line configuration. The occlusal surface shoed 2 slopes: 1 buccal and 1 lingual where the angle in between was 130o using a custom V-shaped metallic device. The stainless steel die was then duplicated into twenty epoxy resin dies using silicone impression material. The stainless steel die was scanned by cerec bluecam then crowns were milled by cerec MC XL device by using the 2IPS E.max CAD3 and 2VITA SUPRINITY3 blocks. After milling, the crowns were finished, polished and glazed prior to the crystallization process. The crowns were then seated on their corresponding dies and cementation was made by using rely-x Unicem adhesive resin cement