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

PURPOSE: 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. MATERIALS AND METHODS: 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). RESULTS: 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. CONCLUSIONS: 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%.