Effects of different bleaching time intervals on fracture toughness of enamel

AIM: This study was designed to evaluate the influence of different time intervals of a vital home bleaching procedure on the fracture toughness of bovine enamel. MATERIALS AND METHODS: Labial aspects of 48 bovine incisors were prepared and stored in artificial saliva. The samples were divided into four groups (n = 12) according to the different time intervals of the bleaching procedure: 0, 2, 4, and 6 weeks. The experimental groups were subjected to the bleaching agent; 15% Opalescence PF according to manufacturer's instructions. The fracture toughness (FT) of enamel was assessed using Vickers hardness indentation. Then, FTs were compared statistically by one-way ANOVA (α = 0.05). RESULTS AND DISCUSSION: Different tested time intervals did not significantly influence the fracture toughness of bovine enamel following treatment with 15% carbamide peroxide (P = 0.05) CONCLUSION: 15% Opalescence PF after 6 weeks did not reduce the fracture toughness of human enamel compared with the baseline, 2 and 4-week values.