title: A partially aromatic urethane dimethacrylate as a new substitute for Bis-GMA in restorative composites.
abstract: OBJECTIVE
  The objective of this study was to investigate the use of a new, partially aromatic urethane dimethacrylate in visible-light cured resin-based composite restoratives. Selected mechanical properties, such as flexural strength and flexural modulus of elasticity, of model monomer mixtures and composites containing the new urethane dimethacrylate were investigated and compared to the properties of materials that are based on Bis-GMA, at present the most frequently used cross-linker in restorative composites. In addition, the polymerization shrinkage and the water sorption of selected composites were determined.
  
  
  METHODS
  The flexural strength, flexural modulus of elasticity, and the water sorption were determined according to ISO 4049:2000. Test specimens (rods: 2 mmx2 mmx25 mm; discs: d=15 mm and h=1 mm) of the investigated composites were prepared in stainless steel molds and light-cured (150 mW/cm2, 2x180 s). The flexural strength and flexural modulus of rods were measured after the samples had been stored under dry conditions or in water for 24 h at 37 degrees C as well as after they had been stored in water for 7 days at 37 degrees C. The water sorption was determined with discs. The polymerization shrinkage was calculated from the densities of the uncured composite pastes and cured composites.
  
  
  RESULTS
  Visible light cured mixtures of dimethacrylate diluents with the new urethane dimethacrylate and composites based on these mixtures show a reactivity, flexural strength, flexural modulus of elasticity, polymerization shrinkage and water sorption similar to those of materials that are based on Bis-GMA. The composites did not show any strong deterioration of the mechanical properties after water storage.
authors.affiliation: Research & Development, Ivoclar Vivadent AG, FL-9494 Schaan, Liechtenstein. norbert.moszner@ivoclarvivadent.com
authors.forename: Norbert
authors.initials: N
authors.lastname: Moszner
authors.forename: Urs Karl
authors.initials: UK
authors.lastname: Fischer
authors.forename: Jörg
authors.initials: J
authors.lastname: Angermann
authors.forename: Volker
authors.initials: V
authors.lastname: Rheinberger
mesh_terms: D000042:Absorption; D000327:Adsorption; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D004548:Elasticity; D006801:Humans; D008027:Light; D009682:Magnetic Resonance Spectroscopy; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D018583:Pliability; D011108:Polymers / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry*; D012031:Refractometry; D017550:Spectroscopy, Fourier Transform Infrared; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014520:Urethane / Q000031:analogs & derivatives* / Q000737:chemistry; D014783:Viscosity; D014867:Water / Q000737:chemistry
chemical_list: D003188:Composite Resins; D003432:Cross-Linking Reagents; D003764:Dental Materials; D008689:Methacrylates; D011108:Polymers; D011140:Polyurethanes; D014867:Water; C029824:urethane dimethacrylate luting resin; D014520:Urethane; D017438:Bisphenol A-Glycidyl Methacrylate