Evaluation of Flexural Strength of Different Denture Base Materials Reinforced with Different Nanoparticles

To evaluate the effect of adding Al₂ O₃ , SiO₂ , and TiO₂ nanoparticles in ratios of 1, 3, and 5 wt% to different acrylic resins on flexural strength.

A total of 210 specimens were prepared in 30 groups (n = 7/group) (Control, 1% Al₂ O₃ , 3% Al₂ O₃ , 5% Al₂ O₃ , 1% SiO₂ , 3% SiO₂ , 5% SiO₂ , 1% TiO₂ , 3% TiO₂ , 5% TiO₂ ). The specimens were polished with 200-, 400-, and 600-grit abrasive paper to provide a standard surface before testing and then suspended in distilled water for 30 days. Flexural strength was measured via three-point bending tests. Subsequently, SEM analysis was performed for one specimen from each group. Homogeneity of data was assessed by Kolmogov-Smirnov test followed by two-way ANOVA and Tukey HSD tests (α = 0.05).

There was a significant increase in the flexural strength of polymethylmethacrylate (PMMA) after addition of 1% nanoparticles in both heat-polymerized and autopolymerized acrylic resins (p ˂ 0.05). The flexural strength values of the groups to which Al₂ O₃ and TiO₂ nanoparticles were added exceeded those of the group with SiO₂ addition (p ˂ 0.05). The electron microscopy images revealed that the nanoparticles were more homogeneously dispersed in PMMA with higher flexural strength.

The mechanical properties of PMMA can be improved by the addition of nanoparticles to PMMA; however, the flexural strength values of PMMA decrease with the addition of nanoparticles at higher percentages (3-5%). Hence, the ideal filler ratio corresponds to 1%.