title: Effect of monomer type on the CC degree of conversion, water sorption and solubility, and color stability of model dental composites.
abstract: This study has investigated the influence of BisGMA, BisEMA, BisEMA 30, and two UDMA-based monomers (UDMA and Fit 852), with TEGDMA as co-monomer, on the degree of conversion, water sorption, water solubility, and optical properties of experimental dental composites.
  
  
  
  Materials were formulated at 70/30 molar rations using BisGMA, BisEMA, BisEMA 30, UDMA or FIT 852, as base monomers, combined with TEGDMA. 60wt% of silanated-glass particles was added. Degree of conversion (DC) and polymerization kinetics were monitored using Fourier-transformed infrared spectroscopy in the near-IR range. Water sorption (Wsp) and solubility (Wsl) were assessed using mass variation after 60days water storage. Color was evaluated using a digital spectrophotometer, applying the CIELab parameters 24h after dry storage and 60days after water immersion to calculate ΔE values. All data were analyzed using ANOVA and Tukey's test (pre-set alpha=0.05).
  
  
  
  The BisGMA-based co-monomer mixture presented the lowest DC (62±1%), whereas BisEMA 30 had the highest DC value (95±2%). The highest Wsp was observed for BisEMA 30 (12.2±0.8%), and the lowest for BisEMA (0.4±0.1%). BisEMA has shown the lowest Wsl (0.03±0.01%) and BisEMA 30 the highest one (0.97±0.1%). The ΔE values showed that BisEMA 30 (7.3 color units) and Fit 852 (3.8 color units) altered the color stability providing ΔE>3.3, which is considered clinically unacceptable.
  
  
  
  The chemical composition and structure of the base monomer influenced the degree of conversion, water sorption, water solubility, and color stability. Considering the overall results, it is possible to state that the base monomer BisEMA mixed with the co-monomer TEGDMA presented the best performance in terms of all the parameters tested.
  
  
  
  The resin matrix composition might influence physical property degradation processes and color stability of dental resin composites. Formulations based on BisEMA seem most promising for materials' development.
authors.affiliation: Nucleous for Dental Biomaterials Research, School of Dentistry, Veiga de Almeida University, Rio de Janeiro, RJ, Brazil; School of Dentistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil; School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil. Electronic address: anddy.4@globo.com.
authors.forename: Andrea Soares Q S
authors.initials: AS
authors.lastname: Fonseca
authors.affiliation: School of Dentistry, Federal Fluminense University, Niterói, Brazil.
authors.forename: Allana Dutra
authors.initials: AD
authors.lastname: Labruna Moreira
authors.affiliation: School of Dentistry, Federal Fluminense University, Niterói, Brazil; School of Dentistry, University of São Paulo, Departamento of Biomaterials and Oral Biology, São Paulo, SP, Brazil.
authors.forename: Pedro Paulo A C
authors.initials: PP
authors.lastname: de Albuquerque
authors.affiliation: Institute of Macromolecules, Federal University of Rio de Janeiro,  Rio de Janeiro, Brazil.
authors.forename: Lívia Rodrigues
authors.initials: LR
authors.lastname: de Menezes
authors.affiliation: Biomaterials and Biomechanics, School of Dentistry, Oregon Health and Science University, Portland, OR, USA.
authors.forename: Carmem S
authors.initials: CS
authors.lastname: Pfeifer
authors.affiliation: Nucleous for Dental Biomaterials Research, School of Dentistry, Veiga de Almeida University, Rio de Janeiro, RJ, Brazil; School of Dentistry, Federal Fluminense University, Niterói, Brazil. Electronic address: felipefop@gmail.com.
authors.forename: Luis Felipe J
authors.initials: LF
authors.lastname: Schneider
mesh_terms: D003188:Composite Resins; D003764:Dental Materials; D008422:Materials Testing; D008689:Methacrylates; D058105:Polymerization; D012995:Solubility; D014867:Water
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D008689:Methacrylates; D014867:Water
keywords: Color stability; FTIR spectroscopy; Resin composite; Water solubility; Water sorption