الفهرس 
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Abstract
The present study was performed to Evaluate the influence of different types of abutment substrate on the color of heat pressed ceramic (Empress 2) and the glass infiltrated ceramic (In Ceram alumina). The correlation between color-difference values calculated with two different formulas after cementation of all ceramic specimens to its substrates was also investigated.
In this study a total of 42 ceramic specimens (8 mm in diameter and 1.5 mm in thickness) were used and divided into two main groups each according to the type of ceramic used. Each group was subdivided into three subgroups according to the type of the substrate material used.
The ceramic specimens were cemented to three different types of substrates (ceramized metal, cast metal and composite substrates). Cementation was done by using transparent resin cement.
The color coordinates of the ceramic specimens before and after cementation to its corresponding substrates were detected using a spectrophotometer. The color differences between different types of substrates cemented to its ceramic specimens also was calculated. The following results were obtained:
- The effect of both ceramized metal and cast metal substrates on the color coordinates of both ceramic systems showed similar behavior on the chromacity. Due to red and yellow coloration shows through from the cast metal and ceramized metal backgrounds.