Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 2 1 2005 03 15 13 17 M. Ghavamnasiri A. Habibi-Rad 2015 10 03 Statement of Problem: Due to the growing popularity of vital bleaching by Carbamide Peroxide it is imperative to understand the effect of such agents on enamel and dentine. Purpose: The purpose of this study was to evaluate the effect of a 16% carbamide peroxide bleaching gel; Vivastyle on enamel staining susceptibility. Materials and Methods: Thirty bovine specimens were selected and randomly divided into two groups of fifteen. The experimental group was subjected to Vivastyle gel and then was immersed in coffee, for half an hour daily for three weeks. The control group was only immersed in coffee. The teeth were evaluated by colorimeter readings to measure L*, a*, b* of each tooth. Total color differences between two colors (ΔE) were calculated using the following formula: ΔE= [(ΔL*) 2 + (Δa*) 2+ (Δb*) 2]. ΔE1 represent color difference after bleaching; ΔE2: bleached and immersed in coffee, and ΔE3 immersed in coffee. Results: Mean color difference were: 9.478, 13.808, and 7.230 for ΔE1, ΔE2, and ΔE3 respectively. Paired comparison by Duncan test showed that there was a significant difference between ΔE1 and ΔE2 (P0.000). t-test showed that there was no significant difference between ΔE3 and ΔE1. (P=0.08), however, ΔE3 had significant difference with ΔE2 (P0.000). Conclusion: After vital bleaching, the enamel staining susceptibility is significantly increased. https://fid.tums.ac.ir/index.php/fid/article/view/43 https://fid.tums.ac.ir/index.php/fid/article/download/43/43