Kinetics of apatite formation on a calcium-silicate cement for root-end filling during ageing in physiological-like phosphate solutions.
The bioactivity of calcium silicate mineral trioxide aggregate (MTA) cements has been attributed to their ability to produce apatite in presence of phosphate-containing fluids. This study evaluated surface morphology and chemical transformations of an experimental accelerated calcium-silicate cement as a function of soaking time in different phosphate-containing solutions. Cement discs were immersed in Dulbecco's phosphate-buffered saline (DPBS) or Hank's balanced salt solution (HBSS) for different times (1-180 days) and analysed by scanning electron microscopy connected with an energy dispersive X-ray analysis (SEM-EDX) and micro-Raman spectroscopy. SEM-EDX revealed Ca and P peaks after 14 days in DPBS. A thin Ca- and P-rich crystalline coating layer was detected after 60 days. A thicker multilayered coating was observed after 180 days. Micro-Raman disclosed the 965-cm(-1) phosphate band at 7 days only on samples stored in DPBS and later the 590- and 435-cm(-1) phosphate bands. After 60-180 days, a layer approximately 200-900 μm thick formed displaying the bands of carbonated apatite (at 1,077, 965, 590, 435 cm(-1)) and calcite (at 1,088, 713, 280 cm(-1)). On HBSS-soaked, only calcite bands were observed until 90 days, and just after 180 days, a thin apatite-calcite layer appeared. Micro-Raman and SEM-EDX demonstrated the mineralization induction capacity of calcium-silicate cements (MTAs and Portland cements) with the formation of apatite after 7 days in DPBS. Longer time is necessary to observe bioactivity when cements are immersed in HBSS.
Gandolfi
Maria Giovanna
MG
Laboratory of Biomaterials and Oral Pathology, Department of Odontostomatological Science, Endodontic Clinical Section, University of Bologna, Italy. mgiovanna.gandolfi@unibo.it
Taddei
Paola
P
Tinti
Anna
A
De Stefano Dorigo
Elettra
E
Rossi
Piermaria Luigi
PL
Prati
Carlo
C
D017607:Aluminum Compounds / Q000737:chemistry*; D001031:Apatites / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry*; D002021:Buffers; D002118:Calcium / Q000032:analysis; D002119:Calcium Carbonate / Q000737:chemistry; D017610:Calcium Compounds / Q000737:chemistry*; D011232:Chemical Precipitation; D003460:Crystallization; D004338:Drug Combinations; D004577:Electron Probe Microanalysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007552:Isotonic Solutions / Q000737:chemistry; D007700:Kinetics; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D015591:Microspectrophotometry; D010087:Oxides / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*; D010758:Phosphorus / Q000032:analysis; D016062:Porosity; D012184:Retrograde Obturation; D012387:Root Canal Filling Materials / Q000737:chemistry*; D017640:Silicates / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry; D013059:Spectrum Analysis, Raman; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
D017607:Aluminum Compounds; D001031:Apatites; D001672:Biocompatible Materials; D002021:Buffers; D017610:Calcium Compounds; D004338:Drug Combinations; C072670:Hanks Balanced Salt Solution; D007552:Isotonic Solutions; D010087:Oxides; D010710:Phosphates; D012387:Root Canal Filling Materials; D017640:Silicates; C086631:mineral trioxide aggregate; D010758:Phosphorus; D012965:Sodium Chloride; C030782:carboapatite; D002119:Calcium Carbonate; C031293:calcium silicate; D002118:Calcium