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: Abstract Objective. The aim of this study was to measure dimensional changes due to hygroscopic expansion and the bioactivity of two experimental methacrylate-based dental adhesives either incorporating Bioglass® 45S5 (3-E&RA/BG) or MTA (3-E&RA/WMTA). Materials and methods. 3-E&RA/BG, 3-E&RA/WMTA and a control filler-free resin blend (3-E&RA) were formulated from commercially available monomers. Water sorption (WS) and solubility (SL) behaviour were evaluated by weighing material disks at noted intervals; the relationship between degree of hydration and the glass transition temperature (Tg) was investigated by using differential scanning calorimetry (DSC). In vitro apatite-forming ability as a function of soaking time in phosphate-containing solutions was also determined. Kruskal-Wallis analysis of variance (ANOVA) was used to evaluate differences between groups for maximum WS, SL, net water uptake and the percentage change in Tg values. Post-ANOVA pair-wise comparisons were conducted using Mann-Whitney-U tests. Results. 3-E&RA/BG and 3-E&RA/WMTA exhibited values of maximum WS and net water uptake that were significantly higher when compared to 3-E&RA. However, no statistically significant differences were observed in terms of SL between all the adhesives. The addition of the Bioglass® 45S5 and MTA to the 3-E&RA showed no reduction of the Tg after 60 days of storage in deionized water. ATR Fourier Transform Infrared Spectroscopy (ATR-FTIR) of the filled resin disks soaked in DPBS for 60 days showed the presence of carbonate ions in different chemical phases. Conclusion. Dentine bonding agents comprising calcium-silicates are not inert materials in a simulated oral environment and apatite formation may occur in the intra-oral conditions. Clinical significance. A bioactive dental material which forms apatite on the surface would have several benefits including closure of gaps forming at the resin-dentine interface and potentially better bond strength over time (less degradation of bond).
    Acta odontologica Scandinavica 02/2014; · 1.41 Impact Factor
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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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    ABSTRACT: This study was aimed to evaluate and to compare the push-out bond strength of different brands of mineral trioxide aggregate (MTA) with a calcium enriched mixture cement (CEM).
    European journal of dentistry. 07/2014; 8(3):348-52.


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