Calcium phosphate phase transformation produced by the interaction of the portland cement component of white mineral trioxide aggregate with a phosphate-containing fluid.
The bioactivity of mineral trioxide aggregate (MTA) has been attributed to its ability to produce hydroxyapatite in the presence of phosphate-containing fluids. It is known that stoichiometric hydroxyapatites do not exist in biological systems and do not contribute to the osteogenic potential of calcium phosphate-based biomaterials. Because Portland cement is the active ingredient in white MTA, we have characterized the calcium phosphate phases produced when set white Portland cement was immersed in phosphate-buffered saline using pH and turbidity measurements, scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy, electron diffraction, x-ray diffraction, and Fourier transform-infrared spectroscopy. An amorphous calcium phosphate phase was initially formed that transformed to an apatite phase, with the latter consisting of calcium-deficient, poorly crystalline, B-type carbonated apatite crystallites. Amorphous calcium phosphate is a key intermediate that precedes biological apatite formation in skeletal calcification. Thus, the clinical manifestations of bioactivity with the use of MTA may at least be partially attributed to the mineralization induction capacity of its Portland cement component.
Tay
Franklin R
FR
Department of Oral Biology and Maxillofacial Pathology, School of Dentistry, Medical College of Georgia, Augusta, Georgia 30912-1129, USA. Franklintay@gmail.com
Pashley
David H
DH
Rueggeberg
Frederick A
FA
Loushine
Robert J
RJ
Weller
R Norman
RN
D017607:Aluminum Compounds / Q000737:chemistry*; D001031:Apatites / Q000737:chemistry*; D002021:Buffers; D017610:Calcium Compounds / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*; D018360:Crystallography, X-Ray; D003738:Dental Cements / Q000737:chemistry; D004338:Drug Combinations; D006863:Hydrogen-Ion Concentration; D009391:Nephelometry and Turbidimetry; D010087:Oxides / Q000737:chemistry*; D044367:Phase Transition; D010710:Phosphates / Q000737:chemistry; D012387:Root Canal Filling Materials / Q000737:chemistry*; D017640:Silicates / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
D017607:Aluminum Compounds; D001031:Apatites; D002021:Buffers; D017610:Calcium Compounds; D002130:Calcium Phosphates; D003738:Dental Cements; D004338:Drug Combinations; D010087:Oxides; D010710:Phosphates; D012387:Root Canal Filling Materials; D017640:Silicates; C472247:accelerated Portland cement; C519480:amorphous calcium phosphate; C086631:mineral trioxide aggregate; C030782:carboapatite