title: Study of the bismuth oxide concentration required to provide Portland cement with adequate radiopacity for endodontic use.
abstract: OBJECTIVE
  The purpose of this study was to determine the ideal concentration of bismuth oxide in white Portland cement to provide it with sufficient radiopacity for use as an endodontic material (ADA specification #57).
  
  
  METHODS
  2-mm thick standardized test specimens of white MTA and of white Portland cement, as controls, and of white Portland cement with the experimental addition of 5%, 10%, 15%, 20%, 25% or 30% of bismuth oxide were radiographed and compared with various thicknesses of pure aluminum, using optic density to determine the observed grayscale levels of radiopacity in a scale ranging from 0 to 255. The data was submitted to ANOVA (p<0.05) and the Ryan-Einot-Gabriel-Welch and Quiot test (REGWQ) for multiple comparison of the means.
  
  
  RESULTS
  White Portland cement with 0%, 5%, 10%, 15%, 20%, 25% and 30% of bismuth oxide presented mean readings of 63.3, 95.7, 110.7, 142.7, 151.3, 161.0 and 180.0 respectively. MTA presented a mean reading of 157.3. The readings of MTA and white Portland cement with 15% bismuth oxide did not differ significantly from the reading observed for a thickness of 4 mm of aluminum (145.3), which is considered ideal for a test specimen by ADA specification #57 (2 mm above the thickness of the test specimen).
  
  
  CONCLUSIONS
  White MTA and white Portland cement with 15% bismuth oxide presented the radiopacity required for an endodontic cement.
authors.affiliation: Center for Dental Research, São Leopoldo Mandic University, Campinas, Brazil. carlosesbueno@terra.com.br
authors.forename: Carlos Eduardo da Silveira
authors.initials: CE
authors.lastname: Bueno
authors.forename: Eduardo Gregatto
authors.initials: EG
authors.lastname: Zeferino
authors.forename: Luiz Roberto Coutinho
authors.initials: LR
authors.lastname: Manhães
authors.forename: Daniel Guimarães Pedro
authors.initials: DG
authors.lastname: Rocha
authors.forename: Rodrigo Sanches
authors.initials: RS
authors.lastname: Cunha
authors.forename: Alexandre Sigrist
authors.initials: AS
authors.lastname: De Martin
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry; D001729:Bismuth / Q000737:chemistry; D017610:Calcium Compounds / Q000737:chemistry; D003287:Contrast Media; D003738:Dental Cements / Q000737:chemistry; D004338:Drug Combinations; D010087:Oxides / Q000737:chemistry; D012044:Regression Analysis; D012387:Root Canal Filling Materials / Q000737:chemistry*; D017640:Silicates / Q000737:chemistry
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D003287:Contrast Media; D003738:Dental Cements; D004338:Drug Combinations; D010087:Oxides; D012387:Root Canal Filling Materials; D017640:Silicates; C472247:accelerated Portland cement; C086631:mineral trioxide aggregate; C033301:bismuth oxide; D001729:Bismuth