Dr. MH. Nekoofar

DDS, MSc, DoIBoE, PhD

Tag: X-Ray Diffraction Analysis

  • Crystalline Phases Involved in the Hydration of Calcium Silicate‐Based Cements: Semi‐Quantitative Rietveld X‐Ray Diffraction Analysis

    Abstract

    Chemical comparisons of powder and hydrated forms of calcium silicate cements (CSCs) and calculation of alterations in tricalcium silicate (Ca3SiO5) calcium hydroxide (Ca(OH)2) are essential for understanding their hydration processes. This study aimed to evaluate and compare these changes in ProRoot MTA, Biodentine and CEM cement. Powder and hydrated forms of tooth coloured ProRoot MTA, Biodentine and CEM cement were subjected to X-ray diffraction (XRD) analysis with Rietveld refinement to semi-quantitatively identify and quantify the main phases involved in their hydration process. Data were reported descriptively. Reduction in Ca3SiO5 and formation of Ca(OH)2 were seen after the hydration of ProRoot MTA and Biodentine; however, in the case of CEM cement, no reduction of Ca3SiO5 and no formation of Ca(OH)2 were detected. The highest percentages of amorphous phases were seen in Biodentine samples. Ettringite was detected in the hydrated forms of ProRoot MTA and CEM cement but not in Biodentine.

    Keywords: X-Ray Diffraction Analysis, Chemical Properties, Mineral Trioxide Aggregate

     Crystalline Phases Involved in the Hydration of Calcium Silicate‐Based Cements Semi‐Quantitative Rietveld X‐Ray Diffraction Analysis.pdf

  • X-Ray Diffraction Analysis of MTA Mixed and Placed with Various Techniques

    Abstract

    Objectives The aim of this study was to evaluate the effect of various mixing techniques as well as the effect of ultrasonic placement on hydration of mineral trioxide aggregate (MTA) using X-ray diffraction (XRD) analysis.

    Materials and Methods One gram of ProRoot MTA and MTA Angelus powder was mixed with a 0.34-g of distilled water. Specimens were mixed either by mechanical mixing of capsules for 30 s at 4500 rpm or by manual mixing followed by application of a compaction pressure of 3.22 MPa for 1 min. The mixtures were transferred into the XRD sample holder with minimum pressure. Indirect ultrasonic activation was applied to half of the specimens. All specimens were incubated at 37 °C and 100% humidity for 4 days. Samples were analyzed by XRD. Phase identification was accomplished by use of search-match software utilizing International Centre for Diffraction Data (ICDD).

    Results All specimens comprised tricalcium silicate, calcium carbonate, and bismuth oxide. A calcium hydroxide phase was formed in all ProRoot specimens whereas among MTA Angelus groups, it was found only in the sample mixed mechanically and placed by ultrasonication.

    Conclusions Mechanical mixing followed by ultrasonication did not confer a significant disadvantage in terms of hydration characteristics of MTA.

    Clinical Relevance Clinicians vary in the way they mix and place MTA. These variations might affect their physical characteristics and clinical performance. For ProRoot MTA, the mixing and placement methods did not affect its rheological properties, whereas for MTA Angelus, mechanical mixing combined with ultrasonic placement enhanced the calcium hydroxide phase formation.

    Keywords: Calcium Hydroxide, MTA, Mechanical Mixing, Ultrasonic Agitation, X-ray diffraction Analysis, XRD.

     X-Ray Diffraction Analysis of MTA Mixed and Placed with Various Techniques.pdf

  • Effect of Bismuth Oxide on White Mineral Trioxide Aggregate: Chemical Characterization and Physical Properties

    Aim: To assess the effect of bismuth oxide (Bi2O3) on the chemical characterization and physical properties of White mineral trioxide aggregate (MTA) Angelus. Methodology Commercially available White MTA Angelus and White MTA Angelus without Bi2O3 provided by the manufacturer especially for this study were subjected to the following tests: Rietveld X-ray diffraction analysis (XRD), energy dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), compressive strength, Vickers microhardness test and setting time. Chemical analysis data were reported descriptively, and physical properties were expressed as means and standard deviations. Data were analysed using Student’s t-test and Mann–Whitney U test (P = 0.05).

    Results: Calcium silicate peaks were reduced in the diffractograms of both hydrated materials. Bismuth particles were found on the surface of White MTA Angelus, and a greater amount of particles characterized as calcium hydroxide was observed by visual examination on White MTA without Bi2O3. The material without Bi2O3 had the shortest final setting time (38.33 min, P = 0.002), the highest Vickers microhardness mean value (72.35 MPa, P = 0.000) and similar compressive strength results (P = 0.329) when compared with the commercially available White MTA Angelus containing Bi2O3.
    Conclusion: The lack of Bi2O3 was associated with an increase in Vickers microhardness, a reduction in final setting time, absence of Bi2O3 peaks in diffractograms, as well as a large amount of calcium and a morphology characteristic of calcium hydroxide in EDX/SEM analysis.

     Effect of bismuth oxide on white mineral trioxide.pdf

  • Microstructure and Chemical Analysis of Blood‐Contaminated Mineral Trioxide Aggregate

    Aim: To test the hypothesis that blood contamination has a detrimental effect on the chemical properties of Mineral trioxide aggregate (MTA). Methodology The effects ofwhole, freshhuman blood on the microstructure and elemental chemistry of MTA were evaluated using scanning electron microscopy and energy-dispersive X-ray analysis, respectively. The phase compositions of contaminated and uncontaminatedMTA were also analysed using X-ray diffraction analysis.
    Results: The hydration state of specimens partially mixed with blood were more complete than those mixed entirely with blood and less than those entirely mixed with water. Acicular crystals, characteristic of ettringite, were abundant in specimens mixed entirely with water and absent from specimens mixed partially or entirely with blood. Calcium hydroxide crystals were absent in specimens contaminated entirely with blood and the unhydrated MTA powder, but present in the other groups.
    Conclusion: Mixing MTA with blood resulted in the lack of formation of the crystalline calcium hydroxide in the early stage of the hydration process.

     Microstructure and chemical analysis of.pdf