Purpose: The aim of this study was to evaluate the effect of different bleaching protocols on biaxial flexural strength and micro hardness of two ceramic materials.
Material and Methods: A total of 112 discs, 56 discs of each material, were prepared from Celtra® Duo and VITA ENAMIC® with 10mm diameter and 1.2mm thickness. Each material was divided into 4 groups (n=14) according to the bleaching protocol done: Group 1 Control group “no bleaching", Group 2 home bleaching “Carbamide Peroxide 22%", Group 3 home bleaching “Hydrogen Peroxide 14%" and Group 4 In-office bleaching using diode Laser. For each material, half the number of discs in each group (n=7) were subjected to Biaxial Flexural Test using Universal Testing Machine Instron-3345 together with Instron BlueHill® universal software, while the other half was subjected to Micro-Hardness Test using Tukon™ 1102 Wilson® Hardness Tester. Data was represented by mean and standard deviation (SD) values. Two-way ANOVA was used to study the effect of different tested variables and their interaction on biaxial flexural strength (Mpa) and micro-hardness, The significance level was set at p ≤0.05 within all tests. Statistical analysis was performed with IBM® SPSS® Statistics Version 26 for Windows.
Results: For Biaxial Flexural Strength and Micro-hardness; Celtra duo samples had a significantly higher value than samples made with Vita Enamic for all bleaching groups.
Conclusion: Bleaching resulted in a significant diminution for both biaxial flexural strength and surface micro-hardness of Celtra Duo and Vita Enamic.