title: Ytterbium trifluoride as a radiopaque agent for dental cements.
abstract: OBJECTIVE
  To evaluate the radiopacity, degree of conversion (DC) and flexural strength of an experimental dental cement, with several added radiopaque substances.
  
  
  METHODS
  Titanium dioxide, quartz, zirconia, bismuth oxide, barium sulphate and ytterbium trifluoride were added to the experimental cement in five different concentrations. Radiopacity was evaluated with a phosphor plate system, and the radiodensity of specimens was compared with an aluminium step-wedge. DC was evaluated with FT-infrared spectroscopy following 20 s of photo-activation. Specimens with dimensions of 12 x 2 x 2 mm were used for the flexural strength test. Data were analysed with two-way anova and Tukey's post hoc test.
  
  
  RESULTS
  Radiopacity of the experimental dental cements with barium sulphate and bismuth oxide at 40% and ytterbium fluoride at 30% and 40% showed no significant differences in comparison with 3 mm of Al (181, 96).
  
  
  CONCLUSIONS
  The experimental dental cements with at least 30% added ytterbium trifluoride had satisfactory radiopacity without influencing other properties.
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil. fabricio.collares@ufrgs.br
authors.forename: F M
authors.initials: FM
authors.lastname: Collares
authors.forename: F A
authors.initials: FA
authors.lastname: Ogliari
authors.forename: G S
authors.initials: GS
authors.lastname: Lima
authors.forename: V R C
authors.initials: VR
authors.lastname: Fontanella
authors.forename: E
authors.initials: E
authors.lastname: Piva
authors.forename: S M W
authors.initials: SM
authors.lastname: Samuel
mesh_terms: D010129:4-Aminobenzoic Acid / Q000737:chemistry; D015502:Absorptiometry, Photon; D000535:Aluminum / Q000737:chemistry; D001466:Barium Sulfate / Q000737:chemistry; D001672:Biocompatible Materials / Q000737:chemistry; D001729:Bismuth / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002164:Camphor / Q000031:analogs & derivatives / Q000737:chemistry; D003287:Contrast Media / Q000737:chemistry*; D003738:Dental Cements / Q000737:chemistry*; D005459:Fluorides / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D044367:Phase Transition; D055668:Photochemical Processes; D018583:Pliability; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D011791:Quartz / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013314:Stress, Mechanical; D013997:Time Factors; D014025:Titanium / Q000737:chemistry; D015018:Ytterbium / Q000737:chemistry*; D015019:Yttrium / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry; D062366:para-Aminobenzoates
chemical_list: D001672:Biocompatible Materials; D003287:Contrast Media; D003738:Dental Cements; D008689:Methacrylates; D011109:Polymethacrylic Acids; D062366:para-Aminobenzoates; C499362:yttria stabilized tetragonal zirconia; C102799:ytterbium fluoride; D011791:Quartz; C020946:triethylene glycol dimethacrylate; C009495:titanium dioxide; D001466:Barium Sulfate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; D015019:Yttrium; C005044:hydroxyethyl methacrylate; D002164:Camphor; C030747:ethyl 4-dimethylaminobenzoate; C033301:bismuth oxide; D015040:Zirconium; D000535:Aluminum; D014025:Titanium; D015018:Ytterbium; D005459:Fluorides; C553149:camphorquinone; C028541:zirconium oxide; D010129:4-Aminobenzoic Acid; D001729:Bismuth