الفهرس 
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Abstract
Summary
This in-vitro study was designed to evaluate marginal adaptaion and internal fit before bonding to
titanium insert as well as retentive strength after bonding and thermocycling of two
hybrid-abutment-crowns made from 2 materials; monolithic lithium disilicate and BioHPP.
Twenty-eight implant analogs; were embedded perpendicularly in an auto-polymerizing resin.
Twenty-eight hybrid-abutment-crowns simulating a maxillary first premolar were designed
using CAD software with a modification in the design to include projections beyond the
occlusal surface were designed with a round perforation of 2 mm to provide the attachment of
stainless steel wires for pull-out testing and milled from CAD/CAM wax blocks for
standardization then after milling lithium disilicate and Biohpp hybrid abutment crowns
were pressed. These hybrid-abutnent-crowns were divided into two main groups according to type
of material (n=14): lithium disilicate and BioHPP. Each group was sub-divided into two
subgroups (n=7): Subgroup A: Evaluation of marginal and internal fit before bonding and
Subgroup B: Evaluation of retentive strength after adhesive bonding and thermocyclying.
Marginal gap was assessed using stereomicroscopic images and using 3D analysis superimposition
software (Geomagic Control X 2018; 3D Systems) and internal gap was assessed using
3D analysis superimposition software (Geomagic Control X 2018; 3D Systems).