title: Aging studies of light cured dimethacrylate-based dental resins and a resin composite in water or ethanol/water.
abstract: OBJECTIVE
  To study the aging of neat resins, prepared from bis-GMA, UDMA, D(3)MA or a mixture of bis-GMA/UDMA/D(3)MA (65/20/15 w/w/w), in water or 75% (v/v) ethanol/water 37 degrees C. Also the study of aging of Heliomolar RO, which is a radiopaque, microfilled, light cured composite, the resin matrix of which is the copolymer of bis-GMA/UDMA/D(3)MA (65/20/15 w/w/w).
  
  
  METHODS
  Samples of neat resins and Heliomolar RO prepared by light curing were immersed in water or 75% (v/v) ethanol/water 37 degrees C, for 1, 7 or 30 days. Then the flexural and tensile strength were determined. The fractured surface of samples after the flexural tests was observed by scanning electron microscopy.
  
  
  RESULTS
  Bis-GMA and copolymer resin did not showed any significant change in mechanical properties after immersion in water or 75% (v/v) ethanol/water 37 degrees C, for 30 days. On the contrary UDMA, D(3)MA and the composite Heliomolar RO showed a significant decrease.
  
  
  CONCLUSIONS
  The results obtained showed that the effect of aging in water or ethanol/water solution on mechanical properties of a light cured dimethacrylate resin depends on the chemical structure of resin. In the case of resin composite this effect depends on the filler-matrix bond strength.
authors.affiliation: Laboratory of Organic Chemical Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-54 124 Thessaloniki, Greece. siderid@chem.auth.gr
authors.forename: Irini D
authors.initials: ID
authors.lastname: Sideridou
authors.forename: Maria M
authors.initials: MM
authors.lastname: Karabela
authors.forename: Dimitris N
authors.initials: DN
authors.lastname: Bikiaris
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D000431:Ethanol / Q000737:chemistry*; D006801:Humans; D007101:Immersion; D008027:Light; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D018583:Pliability; D011140:Polyurethanes / Q000737:chemistry; D012997:Solvents / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature; D013718:Tensile Strength; D013997:Time Factors; D014867:Water / Q000737:chemistry*
chemical_list: D003188:Composite Resins; D003764:Dental Materials; C470818:Heliomolar Flow; D008689:Methacrylates; D011140:Polyurethanes; D012997:Solvents; C524844:decamethylenediol dimetacrylate; D014867:Water; C029824:urethane dimethacrylate luting resin; D000431:Ethanol; D017438:Bisphenol A-Glycidyl Methacrylate