الفهرس 
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Abstract
Summary and conclusion
This is invitro study was carried out to evaluate the translucency and
color stability of bleached veneer shades with different resin cement.
42 IPS E-max Cad discs were fabricated with cad/cam according to
manufacture’s instructions. their dimension was 10 mm in diameter and
0.5mm in thickness. They were divided into two main groups 21 each as the
following:
group 1: IPS E.max CAD discs shade BL1
Sub groups: “7 for each”
1. Control group samples without cement.
2. Samples with underlying resin cement shade +2.
3. Samples with underlying resin cement shade clear.
group 2: (n=21): IPS E.max CAD discs shade BL3.
Sub groups: “7 for each”
1. Control group without resin cement.
2. With underlying resin cement shade +2.
3. With underlying resin cement shade Clear.
Samples Preparation:
42 discs shaped specimens of IPS E-max CAD with BL1 & BL3 shades
will be milled by CAD\CAM 0.5 mm thickness10 mm diameter.
Samples had been finished crystallization and glazing.
In this study 2 different shades of resin cement NLC (+2, Clear). The
specimens were cemented on PMMA discs 1mm thickness10 mm diameter
shade A2 to mimic tooth, with uniform thickness of resin cement (0.1 mm)
Translucency and color of all specimens was measured three times
before cementation and after cementaion with two different shades of resin
cement by using Cary 5000 spectrophotometer.
The spectrophotometer measured color changes (ΔE) of ceramic discs
according to CIE (Commission Internationale de l’Eclairage) L*a*b* system
with a standard illuminant D65 in reflectance mode.
Translucency parameter analysis is calculated by color difference
between black (B) and white (W) background readings. TP was calculated
according to the following equation:
TP= [(L*B–L*W)2 + (a*B–a*W)2+(b*B–b*W)2] ½.
It was found that the highest TP recorded with IPS E-max Cad shade
BL1 without cement (15.19±0.61) while the lowest TP recorded with IPS Emax
cad shade BL3 with cement shade +2 (10.59±0.52)
the masking ability of cement is better while using IPS Emax cad shade
BL1 with underlying cement shade +2 while using cement shade clear gave
almost close results whether it had been used under BL1 or BL3 IPS E-max
cad discs