title: Influence of viscosity and amine content on C==C conversion and color stability of experimental composites.
abstract: OBJECTIVE
  To investigate the influence of camphorquinone (CQ):amine ratio on the degree of CC conversion (DC) and color stability of experimental dental composites formulated with different co-monomer viscosities, indirectly determined by variations in the co-monomer ratios.
  
  
  METHODS
  Experimental composites were formulated in two different BisGMA:TEGDMA molar ratios (50:50 and 70:30). Viscosities were assessed with a viscometer. For each composite formulation, four different CQ:amine ratios were added: 1:1, 1:2, 1:3 or 1:4 mol%. Materials were loaded with 40 wt% of silanized glass particles. DC was determined by Fourier-transformed infrared spectroscopy with attenuated reflectance mode (ATR-FTIR). A spectrophotometer was used to measure the CIE L*a*b* color coordinates 24h after polymerization and after 2 months stored in water. Color changes (ΔE) were calculated. Data were statistically analyzed using analyses of variance (ANOVA), Tukey's and Student-t tests (α=0.05).
  
  
  RESULTS
  The 50:50 BisGMA:TEGDMA co-monomer showed lower viscosity than 70:30. DC was affected by CQ:amine ratio, and not by the co-monomer viscosity, but the interaction between these two factors was significant. a* and b* coordinates were dependent on CQ:amine or BisGMA:TEGDMA ratios, while L* was not. b* values were directly related to the amount of amine in the formulation, regardless of co-monomer viscosity. ΔE was dependent on the amount of amine, but not on the viscosity of the material.
  
  
  CONCLUSIONS
  DC was influenced by the CQ:amine ratio. The influence of viscosity on DC was dependent on the CQ:amine ratio and exhibited distinguished behavior. a* and b* coordinates were affected by CQ:amine and BisGMA:TEGDMA ratios. The color change (ΔE) was affected by CQ:amine ratio, but not by viscosity.
authors: Post-graduation Program in Dentistry, Dental School, University of Passo Fundo, Passo Fundo, RS, Brazil.
authors: Fernanda Missio
authors: FM
authors: Camargo
authors: Post-graduation Program in Dentistry, Dental School, University of Passo Fundo, Passo Fundo, RS, Brazil.
authors: Álvaro
authors: Á
authors: Della Bona
authors: School of Dentistry, Federal Pelotas University, Pelotas, RS, Brazil.
authors: R R
authors: RR
authors: Moraes
authors: Restorative Dentistry, School of Dentistry, Federal Fluminense University, Niterói, RJ, Brazil.
authors: C R
authors: CR
authors: Coutinho de Souza
authors: Restorative Dentistry, School of Dentistry, Federal Fluminense University, Niterói, RJ, Brazil; Nucleus for Dental Biomaterials Research, School of Dentistry, Veiga de Almeida University, Rio de Janeiro, RJ, Brazil. Electronic address: felipefop@gmail.com.
authors: Luis Felipe
authors: LF
authors: Schneider
mesh_terms: D000588:Amines / Q000737:chemistry*; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002164:Camphor / Q000031:analogs & derivatives* / Q000737:chemistry; D003116:Color; D003188:Composite Resins / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D058105:Polymerization; D011109:Polymethacrylic Acids / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D014783:Viscosity
chemical_list: D000588:Amines; D003188:Composite Resins; D011109:Polymethacrylic Acids; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; D002164:Camphor; C553149:camphorquinone
keywords: Amine; Camphorquinone; Color; Dental composites; Polymerization; Viscosity