Analyses of heavy metals in mineral trioxide aggregate and Portland cement.
BACKGROUND
Portland cement is used in the construction industry as a binder in concrete. It is manufactured from chalk, limestone, and clay, which are clinkered at very high temperatures and ground with gypsum to form Portland cement. The raw materials and the manufacturing process can result in the inclusion of heavy metals in Portland cement. Portland cement with a four to one addition of bismuth oxide is marketed as mineral trioxide aggregate (MTA), which is used mainly as a dental material. Heavy metal inclusion can be of concern because MTA is in contact with hard and soft tissues.


METHODS
Measurements of arsenic, lead, and chromium in hydrated gray and white Portland cement, ProRoot MTA, and MTA Angelus were conducted with graphite furnace atomic absorption spectrophotometry after acid digestion on the hydrated material. The leaching of the metal ions from the solid material in water and simulated body fluid (SBF) was also determined.


RESULTS
All cement types showed high relative values of leached chromium compared with arsenic and lead in both the total metal content and leached species. The gray Portland cement showed the highest total amount of metal. The white Portland and both MTAs had lower values for all the leached metal ions.


CONCLUSIONS
Both MTAs released more arsenic than the amount specified in ISO 9917-1 (2007). Portland cements and MTAs showed evidence of heavy metals in the acid-soluble form as well as leaching in deionized water and SBF. MTA contained levels of arsenic higher than the safe limit specified by the ISO 9917-1 (2007).
Schembri
Matthew
M
Department of Chemistry, University of Malta, Msida, Malta.
Peplow
George
G
Camilleri
Josette
J
D000143:Acids / Q000737:chemistry; D017607:Aluminum Compounds / Q000032:analysis*; D000538:Aluminum Silicates / Q000737:chemistry; D001151:Arsenic / Q000032:analysis; D001826:Body Fluids / Q000737:chemistry; D002119:Calcium Carbonate / Q000737:chemistry; D017610:Calcium Compounds / Q000032:analysis*; D002133:Calcium Sulfate / Q000737:chemistry; D002857:Chromium / Q000032:analysis; D000077215:Clay; D003738:Dental Cements / Q000032:analysis* / Q000737:chemistry; D004058:Diffusion; D004338:Drug Combinations; D006801:Humans; D007854:Lead / Q000032:analysis; D008422:Materials Testing; D019216:Metals, Heavy / Q000032:analysis*; D010087:Oxides / Q000032:analysis*; D012387:Root Canal Filling Materials / Q000032:analysis*; D017640:Silicates / Q000032:analysis*; D012995:Solubility; D013054:Spectrophotometry, Atomic; D014867:Water / Q000737:chemistry
D000143:Acids; D017607:Aluminum Compounds; D000538:Aluminum Silicates; D017610:Calcium Compounds; D003738:Dental Cements; D004338:Drug Combinations; D019216:Metals, Heavy; D010087:Oxides; D012387:Root Canal Filling Materials; D017640:Silicates; C086631:mineral trioxide aggregate; D014867:Water; D002857:Chromium; D007854:Lead; D002119:Calcium Carbonate; D001151:Arsenic; D000077215:Clay; D002133:Calcium Sulfate