الفهرس 
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Abstract
Aim: Mechanical properties of Polymer infiltrated ceramic network (PICN) range
between that of resin-based composites and ceramics. Ongoing research on experimental PICNs
shows impressive and promising results in terms of mechanical properties. The aim of this study
was to evaluate the mechanical properties of a newly fabricated resin infiltrated lithium disilicate
ceramic CAD/CAM block, in terms of; fracture load, flexural strength, fracture toughness,
hardness and brittleness. Commercially available resin infiltrated feldspathic ceramic network
was used as control.
Methodology: IPS e.max CAD/CAM blocks were grinded into powder and used to
produce porous ceramic network (25% porosity). Methylmethacrylate resin was infiltrated and
polymerized to form a dense PICN. Porosity percentage and microstructure were investigated.
Crowns were milled from newly fabricated PICN blocks and Vita Enamic then fracture load test
was performed. Rectangular specimens were prepared from both materials, afterwards, flexural
strength, fracture toughness, brittleness and Vickers’ hardness tests were investigated. Data were
analyzed by independent sample-t test and paired sample-t test (α = 0.05, n = 12).
Results: Newly formulated PICN had significantly higher fracture resistance (1640 N),
fracture toughness (2.6 MPa m1/2) and lower brittleness index (0.89 μm1/2) compared to Vita
Enamic (p < 0.001). In addition, no significant difference was found between the two materials
in terms of hardness (p= 0.68) and flexural strength (p = 0.87).
Conclusion: Newly fabricated PICN material showed enhanced mechanical properties
that can justify its selection and clinical application for successful restorative treatments.
Key words: PICN –Lithium-Disilicate, CAD\ CAM .