title: Evaluation of Bis-GMA/TEGDMA monomers leaching from a hybrid dental composite resin.
abstract: OBJECTIVE
  Postcuring elution of unreacted monomers has harmful effects on mechanical characteristics and biocompatibility of resin composite restorations. The purpose of this study was to evaluate the amount of eluted Bis-GMA and TEGDMA monomers from a hybrid dental composite cured with LED or halogen curing unit after immersing in saliva or water.
  
  
  METHODS
  Thirty-six composite disc specimens (Hybrid Filtek Z250,3M-ESPE, USA) were made and divided in four groups. After polymerization with LED or halogen curing units, samples were immersed in water or saliva for 24 hours. The amounts of each monomer (Bis-GMA and TEGDMA) released in different mediums were detected by high-performance liquid chromatography (HPLC). Data were analyzed with two-way ANOVA and one-way ANOVA tests.
  
  
  RESULTS
  The samples were immersed in water, in both curing methods, released significantly more Bis-GMA than TEGDMA (P<0.05). The total monomers eluted was higher in samples cured with halogen curing unit than LED (P=0.001); in addition, saliva caused elution of more monomer than water (P=0.007).
  
  
  CONCLUSIONS
  In conclusion, chemical property of monomers, power of curing light unit and the type of immersion media play key roles in the quantity of eluted monomers from composite resins. Saliva and halogen curing unit can cause greater monomer leaching from hybrid resins composite.
authors.affiliation: Restorative Department, Dentistry Faculty, Dental Research Center, Tehran University of Medical SciencesTehran, Iran.
authors.forename: M H
authors.initials: MH
authors.lastname: Tabatabaei
authors.forename: S
authors.initials: S
authors.lastname: Arami
authors.forename: S
authors.initials: S
authors.lastname: Zandi
authors.forename: S H
authors.initials: SH
authors.lastname: Bassir
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate; D008422:Materials Testing; D011092:Polyethylene Glycols; D011109:Polymethacrylic Acids
chemical_list: D011109:Polymethacrylic Acids; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate