title: Effect of bismuth oxide on white mineral trioxide aggregate: chemical characterization and physical properties.
abstract: OBJECTIVE
  To assess the effect of bismuth oxide (Bi2 O3 ) on the chemical characterization and physical properties of White mineral trioxide aggregate (MTA) Angelus.
  
  
  METHODS
  Commercially available White MTA Angelus and White MTA Angelus without Bi2 O3 provided by the manufacturer especially for this study were subjected to the following tests: Rietveld X-ray diffraction analysis (XRD), energy-dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), compressive strength, Vickers microhardness test and setting time. Chemical analysis data were reported descriptively, and physical properties were expressed as means and standard deviations. Data were analysed using Student's t-test and Mann-Whitney U test (P = 0.05).
  
  
  RESULTS
  Calcium silicate peaks were reduced in the diffractograms of both hydrated materials. Bismuth particles were found on the surface of White MTA Angelus, and a greater amount of particles characterized as calcium hydroxide was observed by visual examination on White MTA without Bi2 O3 . The material without Bi2 O3 had the shortest final setting time (38.33 min, P = 0.002), the highest Vickers microhardness mean value (72.35 MPa, P = 0.000) and similar compressive strength results (P = 0.329) when compared with the commercially available White MTA Angelus containing Bi2 O3 .
  
  
  CONCLUSIONS
  The lack of Bi2 O3 was associated with an increase in Vickers microhardness, a reduction in final setting time, absence of Bi2 O3 peaks in diffractograms, as well as a large amount of calcium and a morphology characteristic of calcium hydroxide in EDX/SEM analysis.
authors.affiliation: School of Dentistry, Universidade Luterana do Brasil, Canoas, RS, Brazil.
authors.forename: R
authors.initials: R
authors.lastname: Grazziotin-Soares
authors.forename: M H
authors.initials: MH
authors.lastname: Nekoofar
authors.forename: T E
authors.initials: TE
authors.lastname: Davies
authors.forename: A
authors.initials: A
authors.lastname: Bafail
authors.forename: E
authors.initials: E
authors.lastname: Alhaddar
authors.forename: R
authors.initials: R
authors.lastname: Hübler
authors.forename: A L S
authors.initials: AL
authors.lastname: Busato
authors.forename: P M H
authors.initials: PM
authors.lastname: Dummer
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry*; D001729:Bismuth / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D004338:Drug Combinations; D008855:Microscopy, Electron, Scanning; D010087:Oxides / Q000737:chemistry*; D017640:Silicates / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D014961:X-Ray Diffraction
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D004338:Drug Combinations; D010087:Oxides; D017640:Silicates; C086631:mineral trioxide aggregate; C033301:bismuth oxide; D001729:Bismuth
keywords: X-ray diffraction analysis; chemical properties; energy-dispersive X-ray; mineral trioxide aggregate; physical properties; radiopacifiers