Study of the bismuth oxide concentration required to provide Portland cement with adequate radiopacity for endodontic use.
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.
Bueno
Carlos Eduardo da Silveira
CE
Center for Dental Research, São Leopoldo Mandic University, Campinas, Brazil. carlosesbueno@terra.com.br
Zeferino
Eduardo Gregatto
EG
Manhães
Luiz Roberto Coutinho
LR
Rocha
Daniel Guimarães Pedro
DG
Cunha
Rodrigo Sanches
RS
De Martin
Alexandre Sigrist
AS
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
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