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

Abstract

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%.

Keywords: Flexural strength; SEM; nanoparticle; polymethylmethacrylate.