title: Effect of silver nano particles on flexural strength of acrylic resins.
abstract: OBJECTIVE
  Poly(methyl methacrylate), PMMA, is widely used for fabrication of removable orthodontic appliances. Silver nano particles (AgNps) have been added to PMMA because of their antimicrobial properties. The aim of this study is to investigate the effect of AgNps on the flexural strength of PMMA.
  
  
  METHODS
  Acrylic liquid containing 0.05% and 0.2% AgNps was prepared for two kinds of acrylic resins: Rapid Repair &Selecta Plus. Two groups without AgNps were used as control groups. For each one, flexural strength was investigated via Three Point Bending method for the 15 acrylic blocks. Two-way ANOVA, one way ANOVA and Tukey tests were used for statistical analysis.
  
  
  RESULTS
  Rapid Repair without AgNps showed the highest flexural strength. Addition of 0.05% AgNps to Rapid Repair, significantly decreased its flexural strength while, continuing the addition up to 0.2% increased it nearly up to its primary level. In contrast, addition of AgNps to Selecta Plus increased its flexural strength but addition of 0.05% nano particles was more effective than 0.2%.
  
  
  CONCLUSIONS
  The effect of AgNps on flexural strength of PMMA depends on several factors including the type of acrylics and the concentrations of nano particles.
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, Tehran University of Medical Sciences, Kargar Shomali Avenue, Tehran, Iran.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Sodagar
authors.forename: Mohammad Zaman
authors.initials: MZ
authors.lastname: Kassaee
authors.forename: Azam
authors.initials: A
authors.lastname: Akhavan
authors.forename: Negar
authors.initials: N
authors.lastname: Javadi
authors.forename: Sepideh
authors.initials: S
authors.lastname: Arab
authors.forename: Mohammad Javad
authors.initials: MJ
authors.lastname: Kharazifard
mesh_terms: D003799:Dental Stress Analysis; D004548:Elasticity; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000032:analysis; D008768:Methylmethacrylates; D012834:Silver
chemical_list: D008768:Methylmethacrylates; D012834:Silver