الفهرس 
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Abstract
Summary
This study evaluated the fracture strength and marginal gap of two
different types of hybrid ceramic crowns in comparison to lithium disilicate
ceramics.
A maxillary premolar was prepared to receive all ceramic crowns . The
prepared tooth was duplicated in to fifteen epoxy resin working dies using
silicon duplicating moulds.
Each die was scanned using the Omnicam scanner, then milling of five
Vita Suprinity ,five E. max and five Vita Enamic crowns using the cerec in
lab 3D system.
Finshing and polishing of Vita Enamic crowns. Finishing and
crystallization of Vita suprinity and E. max crowns.
Measuring of vertical marginal gap before cementation using a etallurgic
microscope at eight points of each crown. The fabricated crowns were
adhesively cemented with panavia F.2 adhesive resin cement on the
corresponding epoxy dies. The fracture strength test was done using a universal
testing machine.
Results: showed that Vita suprinity crowns (80.14 ± 7.64) had a
statistically significant higher marginal gap than that of E.max (60.13 ±3.63)
and Vita Enamic (55.56 ± 7.20).The E.max crowns (1761.6 ±101.0) and Vita
suprinity (1633.5 ± 149.5 ) had a significantly higher fracture strength value
than Vita enamic ( 1002.8 ± 78.9)