The effect of TiO2 and SiO2 nanoparticles on flexural strength of poly (methyl methacrylate) acrylic resins

Purpose: TiO2 and SiO2 nanoparticles are products of nanotechnology which have been incorporated to acrylic resins (AR) in order to induce antimicrobial properties. However, as additives they can affect the mechanical properties of the final product. The aim of this study was to survey the effects of TiO2 and SiO2 nanoparticles on flexural strength (Fs) of poly (methyl methacrylate) acrylic resins. Methods: Acrylic specimens (Selecta Plus) in size of 5 x 10 (+/- 0.2) x 3.3 (+/- 0.2) mm were prepared and divided into 7 groups: AR containing nanoTiO(2), SiO2 and TiO2 with SiO2 in two concentration of 1% and 0.5%, in addition to a control group. To prepare nano AR, nanoparticles were added to the monomer. All specimens were stored in 37 degrees C distilled water and underwent Fs test by universal testing machine (Zwick). Results: The maximum mean flexural strength (43.5 MPa) belongs to the control group and AR containing 0.5% of both TiO2 and SiO2 demonstrated the minimum mean Fs (30.1 MPa). Resins contained TiO2, demonstrated lower values of Fs than those contained SiO2 with the same concentration, but the differences were not significant (P > 0.05). Conclusion: Incorporation of TiO2 and SiO2 nanoparticles into acrylic resins can adversely affect the flexural strength of the final products, and this effect is directly correlated with the concentration of nanoparticles. (C) 2012 Japan Prosthodontic Society. Published by Elsevier Ireland. All rights reserved.