title: Analysis of long-term monomer elution from bulk-fill and conventional resin-composites using high performance liquid chromatography.
abstract: OBJECTIVE
  The aim of this study was to assess monomer elution from bulk-fill and conventional resin-composites stored in different media using high performance liquid chromatography (HPLC) for up to 3 months.
  
  
  METHODS
  Six bulk-fill (SureFil SDR, Venus Bulk Fill, X-tra base, Filtek Bulk Fill flowable, Sonic Fill, and Tetric EvoCeram Bulk Fill) and eight conventional resin-composites (Grandioso Flow, Venus Diamond Flow, X-Flow, Filtek Supreme XTE, Grandioso, Venus Diamond, TPH Spectrum, and Filtek Z250) were tested. Cylindrical samples (n=5) were immersed in water, 70% ethanol/water solution (70% E/W), and artificial saliva and stored at 37°C for 24h, 1 month, and 3 months. The storage solutions were analysed with HPLC. Data were analysed with repeated measures ANOVA, one-way ANOVA, and Tukey post hoc test at α=0.05.
  
  
  RESULTS
  Monomers detected in water and artificial saliva were TEGDMA, DEGDMA, UDMA, and TCD-DI-HEA. No eluted monomers were detected from X-tra base and Sonic fill in these media. All monomers showed a variable extent of elution into 70% E/W with significantly higher amounts than those detected in water and artificial saliva. Significantly higher elution was detected from UDMA-BisEMA based composites compared to BisGMA and BisGMA-BisEMA based systems in 70% E/W. The rate of elution into different media varied between different monomers and was highly dependent on the molecular weight of the eluted compounds.
  
  
  CONCLUSIONS
  Elution from bulk-fill resin-composites is comparable to that of conventional materials despite their increased increment thickness. Monomer elution is highly dependent on the hydrophobicity of the base monomers and the final network characteristics of the resin-matrix.
authors.affiliation: School of Dentistry, The University of Manchester, Manchester, UK; Department of Oral and Maxillofacial Rehabilitation, King Abdulaziz University, Jeddah, Saudi Arabia.
authors.forename: Ruwaida Z
authors.initials: RZ
authors.lastname: Alshali
authors.affiliation: Prosthodontic Department, University of Jordan, Amman, Jordan.
authors.forename: Nesreen A
authors.initials: NA
authors.lastname: Salim
authors.affiliation: Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK.
authors.forename: Rehana
authors.initials: R
authors.lastname: Sung
authors.affiliation: School of Dentistry, The University of Manchester, Manchester, UK.
authors.forename: Julian D
authors.initials: JD
authors.lastname: Satterthwaite
authors.affiliation: School of Dentistry, The University of Manchester, Manchester, UK. Electronic address: nick.silikas@manchester.ac.uk.
authors.forename: Nick
authors.initials: N
authors.lastname: Silikas
mesh_terms: D002851:Chromatography, High Pressure Liquid; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D008422:Materials Testing; D012464:Saliva, Artificial
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D012464:Saliva, Artificial
keywords: Bulk-fill; Liquid chromatography; Mass spectrometry; Monomer; Resin-composites