title: Kinetics of apatite formation on a calcium-silicate cement for root-end filling during ageing in physiological-like phosphate solutions.
abstract: 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.
authors: Laboratory of Biomaterials and Oral Pathology, Department of Odontostomatological Science, Endodontic Clinical Section, University of Bologna, Italy. mgiovanna.gandolfi@unibo.it
authors: Maria Giovanna
authors: MG
authors: Gandolfi
authors: Paola
authors: P
authors: Taddei
authors: Anna
authors: A
authors: Tinti
authors: Elettra
authors: E
authors: De Stefano Dorigo
authors: Piermaria Luigi
authors: PL
authors: Rossi
authors: Carlo
authors: C
authors: Prati
mesh_terms: 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
chemical_list: 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