title: Monomer elution from nanohybrid and ormocer-based composites cured with different light sources.
abstract: OBJECTIVE
  To study monomer elution from four resin-based composites (RBCs) cured with different light sources.
  
  
  METHODS
  Twenty-eight premolars were randomly allocated to four groups. Standardized cavities were prepared and restored with a nanohybrid (Filtek Supreme XT or Tetric EvoCeram), an ormocer (Admira) or a microhybrid RBC (Filtek Z250) which served as control. Buccal restorations were cured with a halogen and oral restorations with an LED light-curing unit. Elution of diurethane dimethacrylate (UDMA), Bisphenol A diglycidylether methacrylate (BisGMA), triethylene glycol dimethacrylate (TEGDMA) and 2-hydroxyethyl methacrylate (HEMA) was analyzed using high-performance liquid chromatography (HPLC) 1h to 28 days post-immersion in 75% ethanol. Data were analyzed using multivariate and repeated measures analysis of variance (α = 0.05).
  
  
  RESULTS
  The greatest elution of UDMA and BisGMA occurred from Tetric EvoCeram and the least from Filtek Z250 (p < 0.05). LED and halogen light-curing units gave similar results for all RBCs (p > 0.05) except Tetric EvoCeram which showed greater elution for the LED unit (p < 0.05). TEGDMA was below the limit of quantification. HEMA eluted in similar concentrations from Filtek Supreme and Tetric EvoCeram (p > 0.05).
  
  
  CONCLUSIONS
  The two nanohybrid RBCs eluted more cross-linking monomers than the ormocer and the control microhybrid RBC. Continuous elution over 28 days indicates that RBCs act as a chronic source of monomers in clinical conditions. Light source may affect monomer elution since differences were found for one out of four RBCs. Mathematical models for elution kinetics of UDMA and BisGMA indicated two elution mechanisms.
authors.affiliation: Department of Restorative Dentistry and Endodontics, University of Belgrade, School of Dentistry, Rankeova 4, 11000 Belgrade, Serbia.
authors.forename: Dragica
authors.initials: D
authors.lastname: Manojlovic
authors.forename: Marina
authors.initials: M
authors.lastname: Radisic
authors.forename: Tatjana
authors.initials: T
authors.lastname: Vasiljevic
authors.forename: Slavoljub
authors.initials: S
authors.lastname: Zivkovic
authors.forename: Mila
authors.initials: M
authors.lastname: Lausevic
authors.forename: Vesna
authors.initials: V
authors.lastname: Miletic
mesh_terms: D001641:Bicuspid; D017438:Bisphenol A-Glycidyl Methacrylate / Q000032:analysis / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry* / Q000528:radiation effects; D002851:Chromatography, High Pressure Liquid; D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D003432:Cross-Linking Reagents / Q000032:analysis / Q000737:chemistry; D055117:Curing Lights, Dental / Q000145:classification*; D003737:Dental Cavity Preparation / Q000379:methods; D003764:Dental Materials / Q000737:chemistry* / Q000528:radiation effects; D003793:Dental Restoration, Permanent; D000431:Ethanol / Q000737:chemistry; D006801:Humans; D008689:Methacrylates / Q000032:analysis / Q000737:chemistry / Q000528:radiation effects; D053761:Nanocomposites / Q000737:chemistry* / Q000528:radiation effects; D063225:Organically Modified Ceramics; D011092:Polyethylene Glycols / Q000032:analysis / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000032:analysis / Q000737:chemistry; D011140:Polyurethanes / Q000032:analysis / Q000737:chemistry; D012821:Silanes / Q000737:chemistry* / Q000528:radiation effects; D012833:Siloxanes / Q000737:chemistry / Q000528:radiation effects; D012997:Solvents / Q000737:chemistry; D013997:Time Factors
chemical_list: D003188:Composite Resins; D003432:Cross-Linking Reagents; D003764:Dental Materials; C515951:Filtek Supreme Plus; C444701:Filtek Z250; D008689:Methacrylates; D063225:Organically Modified Ceramics; D011109:Polymethacrylic Acids; D011140:Polyurethanes; D012821:Silanes; D012833:Siloxanes; D012997:Solvents; C501891:Tetric EvoCeram; C479084:admira; C029824:urethane dimethacrylate luting resin; C020946:triethylene glycol dimethacrylate; D000431:Ethanol; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; C005044:hydroxyethyl methacrylate