الفهرس 
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Abstract
The aim of the study is to evaluate translucency of three different CAD/CAM veneer materials with different internal relief spaces and different cement shades.
Sixty samples were constructed and classified according to the type of materials into three main groups ( I ) IPS e.max CAD MT , ( II ) VITA Vitablocs Mark II and group ( III ) VITA Suprinity (20 samples each). Each group were subdivided into two subgroups (10 samples each) according to the internal relief space (100 microns and 30 μm).
Each subgroup were further subdivided into six classes according to the type of trial cements used : the control class ( glycerine ) and five trial paste classes according to their shade (Translucent Shade, White Opaque Shade, A1/Light Yellow Shade, A3 Opaque/Yellow Opaque Shade and B0.5/ White Shade (10 samples each) according to shade of the trial cement used.
The color coordinates were measured in the body region of all laminate veneers with different combinations of laminate veneer material, internal relief space, and trial insertion paste color on composite resin abutment A3 using reflectance spectrophotometer device ( Vita Easy shade V).
Results revealed a significant effect from the trial cement paste shades on the final color of all laminate veneers placed with 30 μm and 100 μm internal relies spaces at the body region for glass ceramic, feldspathic and zerconia reinforced glass ceramic laminate veneers .
CONCLUSIONS
With in the limitations of this study design, the following conclusions were drawn:
1- The underlying color of the tested trial insertion pastes caused color change (∆E >3.7) for all ceramic material used in this study.
2-For translucent and A1 trial cement shade groups , It was found that Vitablocs Mark II laminate veneers were more affected by trial insertion paste color than IPS e.max CAD then followed by Vita Suprinity laminate veneers.
3- Vita Suprinity laminate veneers with relative opaqueness were more affected by opaque trial insertion pastes (White Opaque Shade, A3 Opaque/Yellow Opaque Shade and B0.5/ White Shade) than Vitablocs Mark II and IPS e.max CAD laminate veneers.
4- Trial cement paste with different shades is very important for predicting the effect of polymerised resin cements on the final esthetic outcome of ceramic veneers.
5- No significant effect of the two internal relief spaces (30 &100 μm ) with different shades of trial cement paste on translucency of each ceramic material used.