The constitution of mineral trioxide aggregate.
OBJECTIVE
The aim of this study was to determine the constitution of a commercially available root-end filling material, mineral trioxide aggregate, (MTA) (ProRoot MTA, Tulsa Dental, Tulsa, OK, USA). The surface morphology of the material with various treatment conditions was also evaluated.


METHODS
The constitution of two commercial versions of MTA was determined before and after mixing with water. The unset material was analysed using Energy Dispersive Analysis by X-ray (EDAX) in a scanning electron microscope (SEM) and X-ray diffraction (XRD). The first technique identified the constituent elements while XRD analysis identified the compounds or phases present. The set material was evaluated using EDAX. The surface morphology of the material stored under various conditions (100% humidity, immersion in water, or immersion in phosphate solution) was evaluated using SEM.


RESULTS
The EDAX showed the white MTA to be composed primarily of calcium, silicon, bismuth and oxygen, with the gray MTA also having small peaks for iron and aluminum. The XRD analysis showed gray MTA to be composed primarily of tricalcium silicate and dicalcium silicate. The surface morphology of the materials differed under the various conditions, particularly following immersion in phosphate solution with crystal formation.


CONCLUSIONS
The commercial versions of MTA were shown to have broadly similar constitution to ordinary Portland cement except for the addition of bismuth compounds. The white MTA did not contain iron.
Camilleri
Josette
J
Department of Conservative Dentistry and Dental Biomaterials, Guy's, King's and St Thomas Dental Institute, King's College London, Guy's Hospital, London SE1 9RT, UK.
Montesin
Franco E
FE
Brady
Ken
K
Sweeney
Richard
R
Curtis
Richard V
RV
Ford
Thomas R Pitt
TR
D000535:Aluminum / Q000032:analysis; D017607:Aluminum Compounds / Q000032:analysis* / Q000737:chemistry; D001729:Bismuth / Q000032:analysis; D002118:Calcium / Q000032:analysis; D017610:Calcium Compounds / Q000032:analysis* / Q000737:chemistry; D003461:Crystallography; D004338:Drug Combinations; D004577:Electron Probe Microanalysis; D006801:Humans; D006813:Humidity; D007101:Immersion; D007501:Iron / Q000032:analysis; D008855:Microscopy, Electron, Scanning; D010087:Oxides / Q000032:analysis* / Q000737:chemistry; D010100:Oxygen / Q000032:analysis; D010710:Phosphates / Q000737:chemistry; D012387:Root Canal Filling Materials / Q000032:analysis* / Q000737:chemistry; D017640:Silicates / Q000032:analysis* / Q000737:chemistry; D012825:Silicon / Q000032:analysis; D013499:Surface Properties; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
D017607:Aluminum Compounds; D017610:Calcium Compounds; D004338:Drug Combinations; D010087:Oxides; D010710:Phosphates; D012387:Root Canal Filling Materials; D017640:Silicates; C086631:mineral trioxide aggregate; D014867:Water; D000535:Aluminum; D007501:Iron; D010100:Oxygen; D002118:Calcium; D001729:Bismuth; D012825:Silicon