الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
This study designed to evaluate the effect of ceramic type, thickness and background color on either zirconia reinforced lithium silicate (Vita Suprinity) or lithium disilicate (IPS e.max CAD) on the final color of restoration. A total of 56 Vita Suprinity (n=28) and IPS e.max CAD (n=28) plates were sectioned under water irrigation with a precision cutting machine IsoMet 4000 into rectangular plates with a dimensions (12 x 14 mm) two thicknesses 1.0 and 1.5 mm. then a digital caliper was used to check that the specimen’s thickness. Either types of ceramic plates were crystallized and glazed according to manufacturing instructions. Also a 56 composite plates with a dimensions (12 x 14 mm) and 2 mm thickness, were made from two different shades A2 (n=28) and C3 (n=28) using a specially constructed teflon mold. All samples (56 samples) divided into to two main tested groups according to ceramic material type, group (1): (28 Samples) Zirconia reinforced lithium silicate (Vita Suprinity) and, group (2): (28 Samples) Lithium disilicate (IPS e.max CAD) which further subdivided into two subgroups according thickness of each ceramic plate, subgroup: 1.0 mm thickness, subgroup: 1.5 mm thickness, the samples were divided into two divisions according to composite background shade into division: A2 composite background shade, division: C3 composite background shade. The ceramic plates of each materials and thicknesses were optically connected with DROP of distilled water to either two composite background shades. The color change ΔE between ceramic-composite assembly and ceramic plates was
measured for all tested groups. Also translucency parameter (TP) was
measured using spectrophotometer for either Vita Suprinity or IPS e.max
CAD at either thickness, by measuring color change ΔE of ceramic
material under black and white background. The ΔE and change in TP
were calculated through the following equations:
ΔE* = (L*a –L*b)2 + (a*a –a*b)2 + (b*a –b*b)2
Where
ΔE*: color change
a: ceramic only
b: ceramic-background assembly
TP = (L*w –L*b)2 + (a*w –a*b)2 + (b*w –b*b)2
Where
TP: translucency parameter
w: white background
b: black background