الفهرس 
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Abstract
In this in-vitro study, lithium disilicate ceramic (e-max CAD) and polymer infiltrated ceramic network ceramics (BIOHPP) endocrowns were constructed.
A standardized preparation were done to all specimens. The measurement of the marginal integrity and fracture resistance was carried out after cementation of the endocrowns with self-adhesive resin cement on the endodontically treated prepared extracted teeth.
Twenty one recently extracted upper premolars were collected. The premolars were selected to be within the following range of dimensions (9-10 bucco-lingual and 7-8 mesio-distal). Teeth were sound and extracted for orthodontic reasons and stored in 0.9% distilled water at room temperature until needed for the study.
The selected teeth were randomly divided into 3 groups according to the type of ceramic material used:
group (A): restoration fabricated from lithium disilicate glass ceramic (IPS e.max CAD) Monolithic.
group (B): restoration fabricated from lithium disilicate glass ceramic (IPS e.max CAD) veneered by e-max ceram.
group (C): Restoration fabricated from modified PEEK veneered with composite veneer (Visio.lign system).
Marginal gap was evaluated using digital microscope showing:
The highest mean marginal gap was found in (e-max bilayered followed by (PEEK) while the lowest mean was found in (e-max monolithic) with no significant difference between (PEEK) and (e-max monolithic).
Fracture resistance was tested using the universal tesing machine showing:
The highest mean value was found in (PEEK) followed by (e-max monolithic) while the lowest mean value was found in (e.max bilayered).