title: Fabrication and evaluation of Bis-GMA/TEGDMA dental resins/composites containing nano fibrillar silicate.
abstract: OBJECTIVE
  To investigate the reinforcement of Bis-GMA/TEGDMA dental resins (without conventional glass filler) and composites (with conventional glass filler) with various mass fractions of nano fibrillar silicate (FS).
  
  
  METHODS
  Three dispersion methods were studied to separate the silanized FS as nano-scaled single crystals and uniformly distribute them into dental matrices. The photo-curing behaviors of the Bis-GMA/TEGDMA/FS resins were monitored in situ by RT-NIR to study the photopolymerization rate and the vinyl double bond conversion. Mechanical properties (flexural strength, elastic modulus and work-of-fracture) of the nano FS reinforced resins/composites were tested, and analysis of variance (ANOVA) was used for the statistical analysis of the acquired data. The morphology of nano FS and the representative fracture surfaces of its reinforced resins/composites were examined by SEM/TEM.
  
  
  RESULTS
  Impregnation of small mass fractions (1% and 2.5%) of nano FS into Bis-GMA/TEGDMA (50/50 mass ratio) dental resins/composites improved the mechanical properties substantially. Larger mass fraction of impregnation (7.5%), however, did not further improve the mechanical properties (one way ANOVA, P>0.05) and may even reduce the mechanical properties. The high degree of separation and uniform distribution of nano FS into dental resins/composites was a challenge. Impregnation of nano FS into dental resins/composites could result in two opposite effects: a reinforcing effect due to the highly separated and uniformly distributed nano FS single crystals, or a weakening effect due to the formation of FS agglomerates/particles.
  
  
  CONCLUSIONS
  Uniform distribution of highly separated nano FS single crystals into dental resins/composites could significantly improve the mechanical properties of the resins/composites.
authors.affiliation: Department of Chemistry, South Dakota School of Mines and Technology, Rapid City, SD 57701-3995, United States.
authors.forename: Ming
authors.initials: M
authors.lastname: Tian
authors.forename: Yi
authors.initials: Y
authors.lastname: Gao
authors.forename: Yi
authors.initials: Y
authors.lastname: Liu
authors.forename: Yiliang
authors.initials: Y
authors.lastname: Liao
authors.forename: Nyle E
authors.initials: NE
authors.lastname: Hedin
authors.forename: Hao
authors.initials: H
authors.lastname: Fong
mesh_terms: D010129:4-Aminobenzoic Acid / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry* / Q000528:radiation effects; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D003764:Dental Materials / Q000737:chemistry* / Q000528:radiation effects; D004548:Elasticity; D000431:Ethanol / Q000737:chemistry; D005898:Glass / Q000737:chemistry; D006801:Humans; D008027:Light; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D053761:Nanocomposites / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry* / Q000528:radiation effects; D018583:Pliability; D011092:Polyethylene Glycols / Q000737:chemistry* / Q000528:radiation effects; D011109:Polymethacrylic Acids / Q000737:chemistry* / Q000528:radiation effects; D012821:Silanes / Q000737:chemistry; D017640:Silicates / Q000737:chemistry* / Q000528:radiation effects; D012997:Solvents / Q000737:chemistry; D019265:Spectroscopy, Near-Infrared; D013314:Stress, Mechanical; D062366:para-Aminobenzoates
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D011109:Polymethacrylic Acids; D012821:Silanes; D017640:Silicates; D012997:Solvents; C009753:fiberglass; D062366:para-Aminobenzoates; C020946:triethylene glycol dimethacrylate; D000431:Ethanol; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; C030746:4-(dimethylamino)benzoic acid; D010129:4-Aminobenzoic Acid