الفهرس 
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Abstract
This study was conducted to determine and compare the optical properties of color, and translucency, as well as the surface roughness of lithium disilicate material LT which is fabricated by two techniques (Press and CAD/CAM technique.)
Twenty ceramic discs with dimensions 6 mm x 2 mm were prepared .IPS e.max Press (ceramic ingots) by lost wax technique and, IPS e.max CAD (ceramic blocks) were milling in a Cerec 3 inlab CAD/CAM system (Sirona) from IPS e.max (Ivoclar, Vivadent) ceramic blocks, and then CIE L*a*b* parameters were taken for each specimen. For optical properties of the discs were measured using a digital spectrophotometer (Vita Easyshade), for determination of the color and translucency. The surface roughness (Ra) for the discs were measured using stereo microscope. For aging, the specimens were stored in 60º distilled water for 8 weeks and then measured again.
The optical properties were assessed one more time after aging, and lso surface roughness. The results showed the IPS e.max CAD group and IPS e.max Press
within the perceptible range of color before and after aging. Compared to he standard A1 shade guide. The IPS e.max CAD higher translucency so it is better esthetic than IPS e.max Press. It, can be used in special cases to mask underlying stains but within limit because it became more translucent by aging. IPS e.max press had rough surface before aging became smoother after aging. All optical properties of IPS e.max CAD and surface roughness were stable by aging. Statistical analysis revealed that there were no correlation between the color and surface roughness.