Mohamed Gamal Hamdy Abddel-Aal, Cherief Adel Mohsen And Shams Waaz Amgad .,

ABSTRACT
Statement Of The Problem: Color Stability Of All Ceramic Restorations Cemented In The Oral Cavity Is Point Of Concern For Both Dentist And Patient. The Aim Of This Study Was To Evaluate Color Stability Of Zirconia Ceramic After Being Subjected To Aging.

Materials & Methods: Fifteen Zirconia Samples Were Constructed In The Form Of Discs By Copy Milling. All The Samples Were 5mm In Diameter But With Different Thickness. The Samples Were Divided Into Three Subgroups According To The Thickness Of The Ceramic C1:0.7mm, C2:1mm And C3:1.5mm. Spectrophotometric Measurements Were Made Before Aging And After Aging Where The Samples Were Immersed In Sodium Hypochlorite 1% For 15 Days As Aging And ?E Was Calculated. Data Were Tabulated And Statistically Analyzed Using One-way Analysis Of Variance (ANOVA). Result: The Most Color Change Occurred With 1.5mm Ceramic (?E:15.55�1.46), The 1mm Ceramic Had A Value About (?E: 5.2�1.27), While The Least Color Change Occurred With 0.7mm Ceramic (?E 3�0.82). Conclusion: There Was Increase In The Color Change With The Increase In The Thickness Of The Ceramic. Aging Had Significant Effect On The Color Stability Of Zirconia Ceramic With The Most Color Change Occured With The Higher Ceramic Thickness. Clinical Recommendation: Zirconia Should Not Be Used With A Thickness More Than 0.7mm To Attain Acceptable Color Stability.