Hebat-Allah Mostafa Mohamed, Ahmed Mohamed Fayed, Dina Wafik Elkassas And Olfat Sayed Hassanien,

ABSTRACT
The Aim Of This Study Was To Evaluate The Color Stability Of Two Different In-office Bleaching Techniques With The Corresponding Post Bleaching Remineralizing Agent And Nano-hydroxyapatite Paste. Materials And Methods. Twenty-eight Patients Were Divided Into Two Groups (n=14), In Accordance With The Bleaching Agent Applied Either Photo Or Chemo Catalyzed Bleaching Agent (25% And 30% Hydrogen Peroxide), And In Accordance With The Remineralizing Agent Applied After Bleaching Either ACP (control Group) Or Nano-hydroxyapatite Paste. Color Stability Was Assessed Using A Spectrophotometer At Baseline, After Twenty-four Hours, After One Week, After Four Weeks And After 24 Weeks Time Intervals. The Results Were Submitted To Statistical Analysis Using Mann-Whiteny U Test And Friedman?s Test. Results. No Statistically Significant Difference Was Found Between Groups That Received ACP And Nano P In The Photo Catalyzed System, Meanwhile A Statistically Significant Difference Was Found With The Chemo Catalyzed Bleaching System After Nano P Application. Conclusion. Nano P Did Enhance The Color Lightening And Stability Of The Chemo Catalyzed Bleaching System.