الفهرس 
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Abstract
Objective:The current study was performed on cerasmart blocks to evaluate the color stability of some dental cements used for cementation of final restoration. The examined material were ceramir cement and adhesive resin cement (rely x unicem).Materials and Methods: Cerasmart blocks were used to prepare thirty nine specimens with the following dimensions: (14 mm*12mm*1.5mm) using ISOMET 4000 with blade speed of (2150 rpm) and continous water irrigation. A final thickness of 1.5 mm was chosen, as it is considered the clinically relevant thickness of hybrid ceramic (cerasmart restoration) and it’s the recommended thickness by the manufacturer. After specimen preparation, they were assigned to three main groups according to the type of cement applied. The first group was the control group which include samples with no cementation, the second group include samples which cemented by rely x cement, and the last one included samples cemented by ceramir cement. Aspecial constructed mould was used to hold standard cerasmart samples.Results:All samples of cements were used in aform of capsule to limit human variation .Cementation has done using customizd cementation device to fix the load applied on the speicemen. Color stability is measured using spectrophotometer.Samples were preparesd and measured twice before immerssion and after immerssion in a coffee for 7 days. Spectrophotometers have gained wide acceptance for color measurement. They are designed to measure the proportion of reflected light from a sample to the light reflected from a white reference across the visible spectrum at 1-20 nm intervals. The results showed that ceramir cements exhibit superior color stability than rely x.Conclusion:According to the results of the present study and within its limitations the following conclusions could be drawn:Cerasmart discs proved to have high color stability after immersion in coffee.Type of cement had a direct effect on crerasmart discs when immersed in coffee.The color stability of the ceramircement was higher than that of the rely x cement.