title: Functionalizing a dentin bonding resin to become bioactive.
abstract: OBJECTIVE
  To investigate chemo-mechanical effects of incorporating alkaline bioactive glass nanoparticles into a light-curable dental resin matrix.
  
  
  METHODS
  An unfilled Bis-GMA/TEGDMA material was infiltrated with up to 20 wt% of ultrafine SiO2-Na2O-CaO-P2O5-Bi2O3 particles. The unfilled and filled resins were investigated regarding their viscosity before setting and compared to commercially available materials. Set specimens were immersed for 21 days in phosphate buffered saline at 37°C. Water uptake, pH, Knoop hardness, and degree of conversion of freshly polymerized and stored samples were investigated. Resin surfaces were viewed and mapped in a scanning electron microscope for the formation of calcium phosphate (Ca/P) precipitates. In addition, Raman spectroscopy was performed. Numeric values were statistically compared (p<0.01).
  
  
  RESULTS
  Viscosity increased with particle loading, but remained below that of a flowable dental composite material. Water uptake into and pH induction from the polymerized samples also increased with particle loading (p<0.01). The addition of 20 wt% nanoparticles had no significant influence on microhardness, yet it slightly (p<0.01) increased the degree of conversion after 21 days. Ca/P precipitates formed on specimens filled with 20 wt% of the particles, while they were scarce on counterparts loaded with 10 wt%, and absent on unfilled resin surfaces.
  
  
  CONCLUSIONS
  The results of the current study show that a Bis-GMA-based resin can be functionalized using alkaline nanoparticles. A material with bioactive properties and similar hardness as the unfilled resin was obtained by incorporating 20wt% of ultrafine SiO2-Na2O-CaO-P2O5-Bi2O3 particles into the resin matrix.
authors.affiliation: Department of Preventive Dentistry, Periodontology and Cariology, Center for Dental Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: Tobias T
authors.initials: TT
authors.lastname: Tauböck
authors.affiliation: Department of Preventive Dentistry, Periodontology and Cariology, Center for Dental Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: Matthias
authors.initials: M
authors.lastname: Zehnder
authors.affiliation: Institute of Polymers, Department of Materials, ETH Zurich, Zurich, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Schweizer
authors.affiliation: Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland.
authors.forename: Wendelin J
authors.initials: WJ
authors.lastname: Stark
authors.affiliation: Department of Preventive Dentistry, Periodontology and Cariology, Center for Dental Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Attin
authors.affiliation: Department of Preventive Dentistry, Periodontology and Cariology, Center for Dental Medicine, University of Zurich, Zurich, Switzerland; Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland. Electronic address: dirk.mohn@chem.ethz.ch.
authors.forename: Dirk
authors.initials: D
authors.lastname: Mohn
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry*; D055117:Curing Lights, Dental; D001840:Dental Bonding; D011092:Polyethylene Glycols / Q000737:chemistry*; D011109:Polymethacrylic Acids / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D011109:Polymethacrylic Acids; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate
keywords: Bioactive filler; Bioglass; Bis-GMA/TEGDMA; Calcium phosphate; Composite material; Microhardness; Nanoparticles