Comparison of the effect of bleaching with 15% carbamide peroxideand 35% hydrogen peroxide on flexural strength of Cention N in selfcuredand dual-cured polymerization modes

Background. The use of bleaching agents might result in microstructural changes in tooth structure and in restorative materials. This study compared the effects of bleaching with 15% carbamide peroxide and 35% hydrogen peroxide on the flexural strength of Cention N restorative material using the self-cured and dual-cured polymerization modes.

Methods. Sixty bar-shaped samples of Cention N restorative material were included in this in vitro study and assigned to three groups (n=20) randomly: control, bleaching with 15% carbamide peroxide and bleaching with 35% hydrogen peroxide. Each group was divided into two subgroups: samples polymerized in the self-cured mode and samples polymerized in the dual-cured mode. Then the flexural strengths of the samples were determined. Two-way ANOVA was used to compare flexural strengths between the three groups in two polymerization modes, followed by post hoc Tukey test. Statistical significance was defined at P<0.05.

Results. The difference in the mean flexural strength was significant in terms of the bleaching regimen (P<0.001), with significantly lower flexural strength in the two bleaching groups compared to the control group. However, the mean flexural strengths were not significantly different in terms of the polymerization mode applied (P=0.14).

Conclusion. The application of 15% carbamide peroxide and 35% hydrogen peroxide bleaching agents decreased the flexural strength of Cention N restorative material. Irrespective of the bleaching regimen, there was no significant difference in the flexural strength of Cention N between the self-curing and dual-curing polymerization modes.