“Retentive Strength, Marginal and Internal Fit of Implant Supported Lithium Disilicate and BioHPP Hybrid Abutment Crowns’’

Abstract

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