title: Evaluation of two Bis-GMA analogues as potential monomer diluents to improve the mechanical properties of light-cured composite resins.
abstract: OBJECTIVE
  The aim of this study was to investigate the influence of new diluent agents, diluent ratio and filler content, on relevant mechanical properties of several novel composite resins containing Bis-GMA as resin matrices, and to compare these with the properties of composites based on TEGDMA, a conventionally used diluent.
  
  
  METHODS
  Two Bis-GMA analogues were synthesized and 20 experimental composite resins were prepared combining three monomer mixtures (Bis-GMA/TEGDMA, Bis-GMA/CH3 Bis-GMA and Bis-GMA/CF3 Bis-GMA), at three dilution rates (85/15, 10/90, 0/100) and three levels of hybrid filler content (barium aluminosilicate glass): 0, 10 and 35%. Flexural strength (FS), modulus of elasticity (ME) and microhardness (VHN) of the composites were evaluated. Five specimens of each material were prepared for each mechanical test, light-cured over 120 s and stored in water at 37 degrees C for 1 week. Three-point bending test was used for FS measurement and VHN was quantified by using a Vickers microindentor. Data were analyzed by ANOVA and Student-Newman-Keuls tests (P<0.05).
  
  
  RESULTS
  Materials with CH3 Bis-GMA showed an enhanced VHN. Mean FS was higher for matrices containing TEGDMA. Overall, dilution favored FS and VHN but not ME. Filler loading specially improved ME and VHN.
  
  
  CONCLUSIONS
  Results correlate with an increase in the extent of polymerization due to the higher flexibility of the less viscous comonomer starting system and the hydrophobic character of the Bis-GMA analogues.
authors.affiliation: IST/ICTPOL, Departamento de Engenharia de Materiais, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal.
authors.forename: Sónia G
authors.initials: SG
authors.lastname: Pereira
authors.forename: Raquel
authors.initials: R
authors.lastname: Osorio
authors.forename: Manuel
authors.initials: M
authors.lastname: Toledano
authors.forename: Teresa G
authors.initials: TG
authors.lastname: Nunes
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D017609:Barium Compounds / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D004548:Elasticity; D005461:Fluorine / Q000737:chemistry; D005898:Glass / Q000737:chemistry; D006244:Hardness; D006801:Humans; D008027:Light; D008422:Materials Testing; D008697:Methane / Q000737:chemistry; D018583:Pliability; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D013314:Stress, Mechanical; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000538:Aluminum Silicates; D017609:Barium Compounds; D003188:Composite Resins; D003764:Dental Materials; D011109:Polymethacrylic Acids; D014867:Water; C020946:triethylene glycol dimethacrylate; D005461:Fluorine; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; D008697:Methane