title: Degree of conversion of bulk-fill compared to conventional resin-composites at two time intervals.
abstract: OBJECTIVE
  The purpose of this study was to assess the degree of conversion (DC) over time, using FTIR spectroscopy for bulk-fill flowable resin composite materials compared to conventional flowable and regular resin composite materials.
  
  
  METHODS
  Eight resin composites were investigated including flowable bulk-fill materials SureFil SDR (SDR), Venus bulk-fill (VBF), x-tra base (XB), and Filtek Bulk Fill (FBF). Conventional flowable and regular composite materials included: Venus Diamond flow (VDF), Grandioso flow (GRF), Venus Diamond (VD), and Grandioso (GR). Degree of conversion (DC) was assessed by Fourier transform infrared spectroscopy using attenuated total reflectance technique. DC was measured for samples immediately post-cure (n=3), and after 24h storage period at 37°C (n=3). Results were analysed using one-way analysis of variance (ANOVA), Bonferroni post hoc test, and independent-samples t-test at α=0.05 significance level.
  
  
  RESULTS
  Immediately post-cure, the mean DC values of the different materials were in the following order: GRF>VDF>SDR>VBF>XB>GR>FBF<VD and ranged from 34.7 to 77.1%. 24h post-cure, DC values were in the following order: GRF>VBF>VD>SDR>VDF>GR>XB<FBF and ranged from 50.9 to 93.1%. GRF showed significantly higher DC values than all other materials at both time intervals while XB and FBF showed significantly lower values at 24h post-cure.
  
  
  CONCLUSIONS
  The 24h post-cure DC values of the bulk-fill composites SDR and VBF are generally comparable to those of conventional composites studied; however, the 24h post-cure DC values of XB and FBF were lower compared to the other materials.
authors.affiliation: School of Dentistry, The University of Manchester, Higher Cambridge Street, Manchester M15 6FH, UK.
authors.forename: Ruwaida Z
authors.initials: RZ
authors.lastname: Alshali
authors.forename: Nick
authors.initials: N
authors.lastname: Silikas
authors.forename: Julian D
authors.initials: JD
authors.lastname: Satterthwaite
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D053761:Nanocomposites / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D058105:Polymerization; D011109:Polymethacrylic Acids / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
chemical_list: D003188:Composite Resins; D003764:Dental Materials; C467913:Filtek Flow; D008689:Methacrylates; D011109:Polymethacrylic Acids; C553871:Surefil SDR Flow; C488393:Venus (composite resin); C542517:Venus flow composite resin; C529733:X-tra fil composite resin; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate
keywords: Bulk-fill; Degree of conversion; FTIR spectroscopy; Resin composite