title: Fluoride release and bioactivity evaluation of glass ionomer: Forsterite nanocomposite.
abstract: BACKGROUND
  The most important limitation of glass ionomer cements (GICs) is the weak mechanical properties. Our previous research showed that higher mechanical properties could be achieved by addition of forsterite (Mg2SiO4) nanoparticles to ceramic part of GIC. The objective of the present study was to fabricate a glass ionomer- Mg2SiO4 nanocomposite and to evaluate the effect of addition of Mg2SiO4 nanoparticles on bioactivity and fluoride release behavior of prepared nanocomposite.
  
  
  METHODS
  Forsterite nanoparticles were made by sol-gel process. X-ray diffraction (XRD) technique was used in order to phase structure characterization and determination of grain size of Mg2SiO4 nanopowder. Nanocomposite was fabricated via adding 3wt.% of Mg2SiO4 nanoparticles to ceramic part of commercial GIC (Fuji II GC). Fluoride ion release and bioactivity of nanocomposite were measured using the artificial saliva and simulated body fluid (SBF), respectively. Bioactivity of specimens was investigated by Fourier transitioned-infrared spectroscopy (FTIR), scanning electronmicroscopy (SEM), Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and registration of the changes in pH of soaking solution at the soaking period. Statistical analysis was carried out by one Way analysis of variance and differences were considered significant if P < 0.05.
  
  
  RESULTS
  The results of XRD analysis confirmed that nanocrystalline and pure Mg2SiO4 powder was obtained. Fluoride ion release evaluation showed that the values of released fluoride ions from nanocomposite are somewhat less than Fuji II GC. SEM images, pH changes of the SBF and results of the ICP-OES and FTIR tests confirmed the bioactivity of the nanocomposite. Statistical analysis showed that the differences between the results of all groups were significant (P < 0.05).
  
  
  CONCLUSIONS
  Glass ionomer- Mg2SiO4 nanocomposite could be a good candidate for dentistry and orthopedic applications, through of desirable fluoride ion release and bioactivity.
authors.affiliation: Department of Materials Engineering, Biomaterials Research Group, Isfahan University of Technology, Isfahan, Iran.
authors.forename: Fatemeh Sadat
authors.initials: FS
authors.lastname: Sayyedan
authors.forename: Mohammadhossein
authors.initials: M
authors.lastname: Fathi
authors.forename: Hossein
authors.initials: H
authors.lastname: Edris
authors.forename: Ali
authors.initials: A
authors.lastname: Doostmohammadi
authors.forename: Vajihesadat
authors.initials: V
authors.lastname: Mortazavi
authors.forename: Farzaneh
authors.initials: F
authors.lastname: Shirani
keywords: Bioactivity; fluoride release; forsterite nanoparticles; glass ionomer cement; sol-gel