title: The effect of TiO2 and SiO2 nanoparticles on flexural strength of poly (methyl methacrylate) acrylic resins.
abstract: OBJECTIVE
  TiO(2) and SiO(2) 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 TiO(2) and SiO(2) nanoparticles on flexural strength (Fs) of poly (methyl methacrylate) acrylic resins.
  
  
  METHODS
  Acrylic specimens (Selecta Plus) in size of 5×10 (±0.2)×3.3 (±0.2)mm were prepared and divided into 7 groups: AR containing nanoTiO(2), SiO(2) and TiO(2) with SiO(2) 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°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 TiO(2) and SiO(2) demonstrated the minimum mean Fs (30.1 MPa). Resins contained TiO(2), demonstrated lower values of Fs than those contained SiO(2) with the same concentration, but the differences were not significant (P>0.05).
  
  
  CONCLUSIONS
  Incorporation of TiO(2) and SiO(2) 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.
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Sodagar
authors.forename: Abbas
authors.initials: A
authors.lastname: Bahador
authors.forename: Safia
authors.initials: S
authors.lastname: Khalil
authors.forename: Atefe Saffar
authors.initials: AS
authors.lastname: Shahroudi
authors.forename: Mohammad Zaman
authors.initials: MZ
authors.lastname: Kassaee
mesh_terms: D003764:Dental Materials; D008422:Materials Testing; D053758:Nanoparticles; D019904:Polymethyl Methacrylate; D012822:Silicon Dioxide; D013314:Stress, Mechanical; D014025:Titanium
chemical_list: D003764:Dental Materials; C009495:titanium dioxide; D012822:Silicon Dioxide; D019904:Polymethyl Methacrylate; D014025:Titanium