Article

Kinetics of apatite formation on a calcium-silicate cement for root-end filling during ageing in physiological-like phosphate solutions.

Laboratory of Biomaterials and Oral Pathology, Department of Odontostomatological Science, Endodontic Clinical Section, University of Bologna, Italy.
Clinical Oral Investigations (Impact Factor: 2.2). 11/2009; 14(6):659-68. DOI: 10.1007/s00784-009-0356-3
Source: PubMed

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.

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    ABSTRACT: Newer tricalcium silicate cement (TSC) may offer biocompatibility with improved working properties. This study aimed to evaluate: (1) the occurrence of mineral deposition at the interface between dentin and two TSC (ProRoot(®) MTA and Biodentine(®)) in simulated body fluid, and (2) to investigate the nature of interfacial layer. Six root dentin segments of 1.5mm thickness were obtained from extracted human teeth and were instrumented with Gates-Glidden drills. The specimens were then randomly filled with either MTA or Biodentine. The specimens were placed in the simulated body fluid containing the same phosphate concentration as blood plasma. After 4 weeks, the specimens were examined with Scanning Electron Microscope (SEM) and Energy Disperse X-ray Spectroscopy (EDX) to measure the thickness of the interfacial layer and Ca/P ratio. Transmission Electron Microcope (TEM) and Selective Area Electron Diffraction (SAED) were conducted to examine the interface ultramicroscopically and to determine the nature of the crystalline structure within interfacial layer. The thickness of interfacial layer was significantly higher in the MTA group (14.5μm vs 4.8μm) (p<0.001). However, there was no significant difference between MTA and Biodentine in Ca/P ratio of interfacial layer (4.1 vs 2.7) (p>0.05). From TEM examination, amorphous calcium phosphate (ACP) was observed in the interface along with the surface of dentin. Conclusions As an alternative to MTA, Biodentine displayed bioactivity by producing an interfacial layer on the root canal dentin even though its thickness was significantly lower than MTA. ACP was observed in the interfacial layer of both biomaterials. Copyright © 2014 Elsevier Ltd. All rights reserved.
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    ABSTRACT: Abstract - Aim: Pulp capping materials are used to protect the exposed vital pulp tissue after removal of deep carious lesions or after traumatic exposure and induce the formation of new dentin. The study compared the chemical-physical properties of novel and long-standing calcium silicate cements versus conventional pulp capping calcium-hydroxide biomaterials. Methodology: Calcium hydroxide-based (Calxyl, Dycal, Life, Lime-Lite) and calcium silicate-based (ProRoot MTA, MTA Angelus, MTA Plus, Biodentine, Tech Biosealer capping, TheraCal) biomaterials were examined. Calcium and hydroxyl ion release, water sorption, interconnected open pores, apparent porosity, solubility and apatite-forming ability in simulated body fluid were evaluated. Results: All calcium silicate materials released more calcium. Tech Biosealer capping, MTA Plus gel and Biodentine showed the highest values of calcium release whilst Lime-Lite had the lowest. All the materials showed alkalizing activity except for Life and Lime-Lite. Calcium silicate materials showed high porosity values: Tech Biosealer capping, MTA Plus gel and MTA Angelus showed the highest values of porosity, water sorption and solubility whilst TheraCal had the lowest. The solubility of water-containing materials was higher and correlated with the liquid-to-powder ratio. Calcium phosphate (CaP) deposits were noted on material surfaces after short ageing times. Scant deposits were detected on Lime-Lite. A CaP coating composed of spherulites was detected on all calcium silicate materials and Dycal after 28 days. The thickness, continuity and Ca/P ratio differed markedly among the materials. MTA Plus showed the thickest coating, ProRoot MTA showed large spherulitic deposits whilst TheraCal presented very small dense spherulites. Conclusions: Calcium silicate are biointeractive (ion-releasing) bioactive (apatite-forming) functional biomaterials. Their solubility is interlinked with pronounced ion release. The large open pore volume and high water sorption provided a broad wet biointeractive surface for the release of calcium and hydroxyl ions. The high rate of calcium releasing and the fast formation of apatite may well explain the role and the function of calcium silicate biomaterials as scaffold to induce new dentin bridge formation and the clinical healing.
    Journal Applied Biomaterials & Functional Materials 2014, in press. 03/2014; eISSN 2280-8000.
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    Dental Materials 12/2014; · 4.16 Impact Factor

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