The effect of an in-office bleaching agent with two different concentrations of titanium dioxide nanoparticles on the biaxial flexural strength, surface microhardness, and roughness of direct and indirect restorative composites | ||
| Egyptian Dental Journal | ||
| Volume 71, Issue 4 - Serial Number 5, October 2025, Pages 3599-3611 PDF (654.92 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/edj.2025.412254.3582 | ||
| Author | ||
| Somaya Ali Saleh* | ||
| Operative Departement, Ain Shams University, Cairo, Egypt, Restorative Dental Science Department, Taibah University, Al Madinah Al Monawarah, Saudi Arabia | ||
| Abstract | ||
| This study evaluated the impact of in-office bleaching treatments incorporating titanium dioxide nanoparticles (TiO₂NPs) on the mechanical properties of three universal nanohybrid composite materials: Grandio Direct, Grandio Indirect, and Admira Fusion. The investigation focused on flexural strength, surface roughness, and microhardness after bleaching with Opalescence Boost (40% hydrogen peroxide) alone and in combination with 5% or 10% TiO₂NPs. A total 360 discs, 120 composite discs for each carried on test, (n=10 per group) were prepared and subjected to four bleaching protocols: no treatment (control), Opalescence Boost only, and Opalescence Boost combined with either 5% or 10% TiO₂NPs. After treatment, samples were stored in artificial saliva before testing. Statistical analysis using two-way ANOVA revealed significant interactions between composite type and bleaching treatment for biaxial flexural strength and surface roughness (p<0.001). For microhardness, only main effects were significant. Grandio composites (direct and indirect) exhibited significantly higher hardness than Admira Fusion. The addition of 5% TiO₂NPs (Group 1) preserved surface roughness and maintained a bleaching effect comparable to the bleaching agent alone (Group 2), whereas 10% TiO₂NPs (Group 3) offered no additional benefit. In conclusion, incorporating 5 wt% TiO₂NPs into an in-office bleaching agent provided a comparable whitening result to conventional bleaching without adversely affecting surface texture or mechanical properties. However, increasing the TiO₂NP concentration to 10 wt% did not further enhance outcomes and may not be clinically beneficial. These findings suggest that lower concentrations of TiO₂NPs can improve the safety profile of bleaching treatments on dental composites. | ||
| Keywords | ||
| nanotechnology; Titanium dioxide nanoparticles; office bleaching; biaxial flexural strength | ||
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