title: Elution of monomers from two conventional dental composite materials.
abstract: OBJECTIVE
  The aim of this study was to determine the elution of monomers of two conventional resin composite materials after different polymerization and storage times.
  
  
  METHODS
  Two resin composites (a hybrid and a flowable) were used. Four groups (n=10, diameter: 4.5mm, thickness: 2mm) of each material were fabricated, one for each polymerization time of: 0s, 20s, 40s, and 80s. The samples were stored in 1ml of 75% ethanol at room temperature, and the storage medium was renewed after 24h, 7 days, and 28 days. From the storage medium that was removed, samples were prepared and evaluated, with LC-MS/MS.
  
  
  RESULTS
  Bisphenol A and UDMA were not detected in the samples. Regardless of the polymerization time, the material or the storage time, a higher amount of BisGMA was eluted compared to TEGDMA. The amount of monomer that was released from the polymerized samples of the hybrid resin composite (Tetric Ceram) was significantly higher (p<0.0001) compared to the flowable (Tetric Flow). No significant difference was found between samples polymerized for 20s compared to 40s concerning the elution of monomers. Only a polymerization time of 80s resulted in a decreased release of monomers. The release of TEGDMA decreased after 28 days; however, the elution of BisGMA remained at high levels.
  
  
  CONCLUSIONS
  The release of monomers remains at a high level for a long time (7-28 days) after polymerization. The 40s that are usually used for the polymerization of resin composites seems insufficient in order to prevent a high release of monomers.
authors.affiliation: Department of Operative Dentistry and Periodontology, Dental School and Hospital, Albert-Ludwigs-University Freiburg, Hugstetter Strasse 55, 79106 Freiburg i. Br., Germany. olga.polydorou@uniklinik-freiburg.de
authors.forename: Olga
authors.initials: O
authors.lastname: Polydorou
authors.forename: Rainer
authors.initials: R
authors.lastname: Trittler
authors.forename: Elmar
authors.initials: E
authors.lastname: Hellwig
authors.forename: Klaus
authors.initials: K
authors.lastname: Kümmerer
mesh_terms: D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D003188:Composite Resins / Q000737:chemistry*; D003793:Dental Restoration, Permanent; D004356:Drug Storage; D000431:Ethanol; D008422:Materials Testing; D044367:Phase Transition; D011092:Polyethylene Glycols / Q000032:analysis; D011109:Polymethacrylic Acids / Q000032:analysis; D018709:Statistics, Nonparametric; D013997:Time Factors
chemical_list: D003188:Composite Resins; D011109:Polymethacrylic Acids; C121818:Tetric ceram; C452226:tetric flow composite resin; C020946:triethylene glycol dimethacrylate; D000431:Ethanol; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate