الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
Advancements in dental research due to the high demands in esthetic dentistry lead to the creation of all ceramic restorations to exactly mimic the appearance of natural teeth and eliminate the need of metal substructures.
In today’s industry full-contour monolithic restorations provide exceptional esthetics without requiring a veneering ceramic and its requisite bond interface, therefore increasing the structural integrity of such restorations.
However, concerns about the effect of porcelain as it causes accelerated wear of the opposing enamel is one of the major drawbacks associated with dental ceramics.
Wear is an inevitable process and the wear that occurs between dental enamel and restorations is a very important factor that has to be considered in the selection of restorative materials in the clinical practice. Therefore, this study was done to compare the wear behavior of monolithic zirconia against natural teeth to lithium disilicate based ceramics and nano-flourapatite veneering glass ceramics with different finishing procedure; polishing and glazing.
This study included 42 specimens of all ceramic disc samples and 42 natural tooth antagonists. They were subdivided according to the all ceramic material into 3 equal groups (n=14). group I included disc samples of nano-flourapatite glass ceramic (IPS e.max Ceram), group II included disc samples of lithium disilicate based ceramic (IPS e.max CAD) and group III included disc samples of zirconia (ZirkonZahn Prettau). Each group was further subdivided into two equal subgroups [A and B] (n=7) according to the surface finish (polishing and glazing).
Construction of all ceramic samples was done according to the manufacturer’s instructions.
For fixation during testing, natural teeth were embedded in epoxy resin molds using a paralleling device to allow accurate centralization of teeth in their molds.
All ceramic disc samples were subjected to thermocycling for 3500 cycles at a changing temperature between 5oC and 55oC which is equivalent to almost one year in a patient’s mouth.
A two-body wear simulator was custom designed to imitate two-body wear situations. The device was programmed to perform 240,000 loading cycles backwards and forwards to clinically simulate one year chewing condition.