الفهرس 
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Abstract
SUMMARY
Translucency is of the most important characteristic of a ceramic material used in prosthodontics to provide high esthetic restoration. Also, the longevity of any fixed prosthesis relies on the strength of the brittle ceramic materials used in everyday practice.
With the increase attention to esthetic restorations and development of new materials in the dental field it is of utmost importance to compare different lithium disilicate based dental ceramics.
Therefore, in our present study, the shear bond strength and translucency of IPS e.max press and GC Initial LiSi Press was investigated.
A total of sixty discs of a 12 mm diameter were constructed from two different materials representing the two different groups in this study (n=30) and further divided into 3 sub-groups (n=10) according to the specimen thickness (0.4mm, 0.8mm and 1.2) for assessment of color change and translucency.
Another twenty discs of 5mm diameter and 2mm thickness were constructed from two different materials representing the two different groups in this study (n=10) for assessment of shear bond strength.
An STL file made using 3D Builder software of the proposed specimen dimensions was imported to milling software of CAD/CAM system and was milled from resin wax.
The milled wax discs were then secured sprued, invested and pressed utilizing lost wax technique for both tested materials according to the manufacturer instruction.
The discs were then evaluated for translucency parameter and color change using spectrophotometer against black and white backgrounds.
All samples to be tested for shear bond strength were cemented to surface treated enamel and cemented with light cure resin cement prior to testing. Then they were subjected to shear bond testing and mode of failure evaluation.
All data were collected, tabulated and statistically analyzed to detect any significant values among the tested groups.
The following results were obtained:
The results for translucency parameters revealed that:
1. GC Initial Lisi Press showed higher translucency parameter than IPS e.max Press.
2. The 0.4mm discs had the highest translucency parameter followed by 0.8mm disc followed by 1.2mm regardless of the material used.
While the results for color change revealed that:
1. IPS e.max press showed higher color change than GC Initial LiSi Press.
2. The 0.4mm discs had the highest color change followed by 0.8mm discs followed by 1.2mm discs regardless of the material.
While the shear bond strength revealed that:
IPS e.max press showed higher shear bond strength than GC Initial LiSi Press.