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Sample records for calcium sulfoaluminate cement

  1. Synthesis of Portland cement and calcium sulfoaluminate-belite cement for sustainable development and performance

    Science.gov (United States)

    Chen, Irvin Allen

    Portland cement concrete, the most widely used manufactured material in the world, is made primarily from water, mineral aggregates, and portland cement. The production of portland cement is energy intensive, accounting for 2% of primary energy consumption and 5% of industrial energy consumption globally. Moreover, portland cement manufacturing contributes significantly to greenhouse gases and accounts for 5% of the global CO2 emissions resulting from human activity. The primary objective of this research was to explore methods of reducing the environmental impact of cement production while maintaining or improving current performance standards. Two approaches were taken, (1) incorporation of waste materials in portland cement synthesis, and (2) optimization of an alternative environmental friendly binder, calcium sulfoaluminate-belite cement. These approaches can lead to less energy consumption, less emission of CO2, and more reuse of industrial waste materials for cement manufacturing. In the portland cement part of the research, portland cement clinkers conforming to the compositional specifications in ASTM C 150 for Type I cement were successfully synthesized from reagent-grade chemicals with 0% to 40% fly ash and 0% to 60% slag incorporation (with 10% intervals), 72.5% limestone with 27.5% fly ash, and 65% limestone with 35% slag. The synthesized portland cements had similar early-age hydration behavior to commercial portland cement. However, waste materials significantly affected cement phase formation. The C3S--C2S ratio decreased with increasing amounts of waste materials incorporated. These differences could have implications on proportioning of raw materials for cement production when using waste materials. In the calcium sulfoaluminate-belite cement part of the research, three calcium sulfoaluminate-belite cement clinkers with a range of phase compositions were successfully synthesized from reagent-grade chemicals. The synthesized calcium sulfoaluminate

  2. Influence of ferrite phase in alite-calcium sulfoaluminate cements

    Science.gov (United States)

    Duvallet, Tristana Yvonne Francoise

    Since the energy crisis in 1970's, research on low energy cements with low CO2- emissions has been increasing. Numerous solutions have been investigated, and the goal of this original research is to create a viable hybrid cement with the components of both Ordinary Portland cement (OPC) and calcium sulfoaluminate cement (CSAC), by forming a material that contains both alite and calcium sulfoaluminate clinker phases. Furthermore, this research focuses on keeping the cost of this material reasonable by reducing aluminum requirements through its substitution with iron. The aim of this work would produce a cement that can use large amounts of red mud, which is a plentiful waste material, in place of bauxite known as an expensive raw material. Modified Bogue equations were established and tested to formulate this novel cement with different amounts of ferrite, from 5% to 45% by weight. This was followed by the production of cement from reagent chemicals, and from industrial by-products as feedstocks (fly ash, red mud and slag). Hydration processes, as well as the mechanical properties, of these clinker compositions were studied, along with the addition of gypsum and the impact of a ferric iron complexing additive triisopropanolamine (TIPA). To summarize this research, the influence of the addition of 5-45% by weight of ferrite phase, was examined with the goal of introducing as much red mud as possible in the process without negatively attenuate the cement properties. Based on this PhD dissertation, the production of high-iron alite-calcium sulfoaluminateferrite cements was proven possible from the two sources of raw materials. The hydration processes and the mechanical properties seemed negatively affected by the addition of ferrite, as this phase was not hydrated entirely, even after 6 months of curing. The usage of TIPA counteracted this decline in strength by improving the ferrite hydration and increasing the optimum amount of gypsum required in each composition

  3. Influence of sodium borate on the early age hydration of calcium sulfoaluminate cement

    Energy Technology Data Exchange (ETDEWEB)

    Champenois, Jean-Baptiste; Dhoury, Mélanie [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze Cedex (France); Cau Dit Coumes, Céline, E-mail: celine.cau-dit-coumes@cea.fr [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze Cedex (France); Mercier, Cyrille [LMCPA, Université de Valenciennes et du Hainaut Cambrésis, 59600 Maubeuge (France); Revel, Bertrand [Centre Commun de Mesure RMN, Université Lille1 Sciences Technologies, Cité Scientifique, 59655 Villeneuve d' Ascq Cedex (France); Le Bescop, Patrick [CEA, DEN, DPC, SECR, F-91192 Gif-sur-Yvette (France); Damidot, Denis [Ecole des Mines de Douai, LGCgE-GCE, 59508 Douai (France)

    2015-04-15

    Calcium sulfoaluminate (CSA) cements are potential candidates for the conditioning of radioactive wastes with high sodium borate concentrations. This work thus investigates early age hydration of two CSA cements with different gypsum contents (0 to 20%) as a function of the mixing solution composition (borate and NaOH concentrations). Gypsum plays a key role in controlling the reactivity of cement. When the mixing solution is pure water, increasing the gypsum concentration accelerates cement hydration. However, the reverse is observed when the mixing solution contains sodium borate. Until gypsum exhaustion, the pore solution pH remains constant at ~ 10.8, and a poorly crystallized borate compound (ulexite) precipitates. A correlation is established between this transient precipitation and the hydration delay. Decreasing the gypsum content in the binder, or increasing the sodium content in the mixing solution, are two ways of reducing the stability of ulexite, thus decreasing the hydration delay.

  4. Surface Corrosion and Microstructure Degradation of Calcium Sulfoaluminate Cement Subjected to Wet-Dry Cycles in Sulfate Solution

    Directory of Open Access Journals (Sweden)

    Wuman Zhang

    2017-01-01

    Full Text Available The hydration products of calcium sulfoaluminate (CSA cement are different from those of Portland cement. The degradation of CSA cement subjected to wet-dry cycles in sulfate solution was studied in this paper. The surface corrosion was recorded and the microstructures were examined by scanning electron microscopy (SEM. The results show that SO42-, Na+, Mg2+, and Cl− have an effect on the stability of ettringite. In the initial period of sulfate attack, salt crystallization is the main factor leading to the degradation of CSA cement specimens. The decomposition and the carbonation of ettringite will cause long-term degradation of CSA cement specimens under wet-dry cycles in sulfate solution. The surface spalling and microstructure degradation increase significantly with the increase of wet-dry cycles, sulfate concentration, and water to cement ratio. Magnesium sulfate and sodium chloride reduce the degradation when the concentration of sulfate ions is a constant value.

  5. Recycling the product of thermal transformation of cement-asbestos for the preparation of calcium sulfoaluminate clinker.

    Science.gov (United States)

    Viani, Alberto; Gualtieri, Alessandro F

    2013-09-15

    According to recent resolutions of the European Parliament (2012/2065(INI)), the need for environmentally friendly alternative solutions to landfill disposal of hazardous wastes, such as asbestos-containing materials, prompts their recycling as secondary raw materials (end of waste concept). In this respect, for the first time, we report the recycling of the high temperature product of cement-asbestos, in the formulation of calcium sulfoaluminate cement clinkers (novel cementitious binders designed to reduce CO₂ emissions), as a continuation of a previous work on their systematic characterization. Up to 29 wt% of the secondary raw material was successfully introduced into the raw mix. Different clinker samples were obtained at 1250 °C and 1300 °C, reproducing the phase composition of industrial analogues. As an alternative source of Ca and Si, this secondary raw material allows for a reduction of the CO₂ emissions in cement production, mitigating the ecological impact of cement manufacturing, and reducing the need for natural resources. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Calcium Sulfoaluminate, Geopolymeric, and Cementitious Mortars for Structural Applications

    Directory of Open Access Journals (Sweden)

    Alessandra Mobili

    2017-09-01

    Full Text Available This paper deals with the study of calcium sulfoaluminate (CSA and geopolymeric (GEO binders as alternatives to ordinary Portland cement (OPC for the production of more environmentally-friendly construction materials. For this reason, three types of mortar with the same mechanical strength class (R3 ≥ 25 MPa, according to EN 1504-3 were tested and compared; they were based on CSA cement, an alkaline activated coal fly ash, and OPC. Firstly, binder pastes were prepared and their hydration was studied by means of X-ray diffraction (XRD and differential thermal-thermogravimetric (DT-TG analyses. Afterwards, mortars were compared in terms of workability, dynamic modulus of elasticity, adhesion to red clay bricks, free and restrained drying shrinkage, water vapor permeability, capillary water absorption, and resistance to sulfate attack. DT-TG and XRD analyses evidenced the main reactive phases of the investigated binders involved in the hydration reactions. Moreover, the sulfoaluminate mortar showed the smallest free shrinkage and the highest restrained shrinkage, mainly due to its high dynamic modulus of elasticity. The pore size distribution of geopolymeric mortar was responsible for the lowest capillary water absorption at short times and for the highest permeability to water vapor and the greatest resistance to sulfate attack.

  7. Obtaining a sulfoaluminate belite cement by industrial waste

    Directory of Open Access Journals (Sweden)

    Elkhadiri, L.

    2003-06-01

    Full Text Available Sulfoaluminate belite clinkers by burning raw at moderate temperatures near 1250 °C were synthesized. The used mixtures were made by calcium carbonate blended to two industrial wastes: low calcium fly ash and phosphogypsum. The clinkers were characterised by X-Ray Diffraction (XRD, Infrared Spectroscopy (FTIR and free lime. The hydraulic behaviour of the obtained cements, by adequate clinkers with 7% of added gypsum, was followed by XRD, scaning electronic microscopy (SEM, FTIR and NMR.

    Los clínkeres belíticos de sulfoaluminatos se obtienen por cocción de crudos a temperaturas moderadas, hacia 1.250 ºC. Esos crudos se componen de carbonato de calcio mezclados con dos subproductos industriales: cenizas volantes pobres en óxido de calcio y fosfoyeso. Los clínkeres obtenidos se caracterizaron a través de Difracción de Rayos X (DRX, Espectroscopia Infrarroja por Transformada de Fourier (FTIR y por la determinación de CaO libre. El comportamiento hidráulico de los cementos elaborados de los clínkeres con el 7% de yeso se estudió por DRX, Microscopía Electrónica de Barrido (SEM, FTIR y Resonancia Magnética Nuclear (RMN

  8. Friedel's salt formation in sulfoaluminate cements: A combined XRD and {sup 27}Al MAS NMR study

    Energy Technology Data Exchange (ETDEWEB)

    Paul, G. [Dipartimento di Scienze ed Innovazione Tecnologica, Università del Piemonte Orientale A. Avogadro, Viale T. Michel 11, 15121 Alessandria (Italy); Boccaleri, E., E-mail: enrico.boccaleri@mfn.unipmn.it [Dipartimento di Scienze ed Innovazione Tecnologica, Università del Piemonte Orientale A. Avogadro, Viale T. Michel 11, 15121 Alessandria (Italy); Buzzi, L.; Canonico, F. [Buzzi Unicem S.p.A., Via L. Buzzi 6, 15033 Casale Monferrato (Italy); Gastaldi, D., E-mail: dgastaldi@buzziunicem.it [Buzzi Unicem S.p.A., Via L. Buzzi 6, 15033 Casale Monferrato (Italy)

    2015-01-15

    Four different binders based on calcium sulfoaluminate cements have been submitted to accelerated chlorination through ionic exchange on hydrated pastes, in order to investigate their ability to chemically bind chloride ions that might reduce chloride penetration. The composition of hydrated cements before and after the treatment was evaluated by means of an X-Ray Diffraction–{sup 27}Al Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy combined study, allowing to take into account even partially amorphous phases and to make quantitative assumption on the relative abundance of the different aluminium-containing phases. It was found that low SO{sub 3} Sulfoaluminate–Portland ternary systems are the most effective in binding chloride ions and the active role played by different members of the AFm family in chloride uptake was confirmed. Moreover, a peculiar behavior related to the formation of Friedel's salt in different pH conditions was also established for the different cements.

  9. Kinetics of calcium sulfoaluminate formation from tricalcium aluminate, calcium sulfate and calcium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xuerun, E-mail: xuerunli@163.com; Zhang, Yu; Shen, Xiaodong, E-mail: xdshen@njut.edu.cn; Wang, Qianqian; Pan, Zhigang

    2014-01-15

    The formation kinetics of tricalcium aluminate (C{sub 3}A) and calcium sulfate yielding calcium sulfoaluminate (C{sub 4}A{sub 3}$) and the decomposition kinetics of calcium sulfoaluminate were investigated by sintering a mixture of synthetic C{sub 3}A and gypsum. The quantitative analysis of the phase composition was performed by X-ray powder diffraction analysis using the Rietveld method. The results showed that the formation reaction 3Ca{sub 3}Al{sub 2}O{sub 6} + CaSO{sub 4} → Ca{sub 4}Al{sub 6}O{sub 12}(SO{sub 4}) + 6CaO was the primary reaction < 1350 °C with and activation energy of 231 ± 42 kJ/mol; while the decomposition reaction 2Ca{sub 4}Al{sub 6}O{sub 12}(SO{sub 4}) + 10CaO → 6Ca{sub 3}Al{sub 2}O{sub 6} + 2SO{sub 2} ↑ + O{sub 2} ↑ primarily occurred beyond 1350 °C with an activation energy of 792 ± 64 kJ/mol. The optimal formation region for C{sub 4}A{sub 3}$ was from 1150 °C to 1350 °C and from 6 h to 1 h, which could provide useful information on the formation of C{sub 4}A{sub 3}$ containing clinkers. The Jander diffusion model was feasible for the formation and decomposition of calcium sulfoaluminate. Ca{sup 2+} and SO{sub 4}{sup 2−} were the diffusive species in both the formation and decomposition reactions. -- Highlights: •Formation and decomposition of calcium sulphoaluminate were studied. •Decomposition of calcium sulphoaluminate combined CaO and yielded C{sub 3}A. •Activation energy for formation was 231 ± 42 kJ/mol. •Activation energy for decomposition was 792 ± 64 kJ/mol. •Both the formation and decomposition were controlled by diffusion.

  10. Calcium Sulfoaluminate Sodalite (Ca 4 Al 6 O 12 SO 4 ) Crystal Structure Evaluation and Bulk Modulus Determination

    KAUST Repository

    Hargis, Craig W.

    2013-12-12

    The predominant phase of calcium sulfoaluminate cement, Ca 4(Al6O12)SO4, was investigated using high-pressure synchrotron X-ray diffraction from ambient pressure to 4.75 GPa. A critical review of the crystal structure of Ca4(Al 6O12)SO4 is presented. Rietveld refinements showed the orthorhombic crystal structure to best match the observed peak intensities and positions for pure Ca4(Al6O 12)SO4. The compressibility of Ca4(Al 6O12)SO4 was studied using cubic, orthorhombic, and tetragonal crystal structures due to the lack of consensus on the actual space group, and all three models provided similar results of 69(6) GPa. With its divalent cage ions, the bulk modulus of Ca4(Al6O 12)SO4 is higher than other sodalites with monovalent cage ions, such as Na8(AlSiO4)6Cl2 or Na8(AlSiO4)6(OH)2·H 2O. Likewise, comparing this study to previous ones shows the lattice compressibility of aluminate sodalites decreases with increasing size of the caged ions. Ca4(Al6O12)SO4 is more compressible than other cement clinker phases such as tricalcium aluminate and less compressible than hydrated cement phases such as ettringite and hemicarboaluminate. © 2013 The American Ceramic Society.

  11. SYNTHESIS AND CHARACTERIZATION OF HIGH BELITE SULFOALUMINATE CEMENT THROUGH RICH ALUMINA FLY ASH AND DESULFURIZATION GYPSUM

    Directory of Open Access Journals (Sweden)

    BING MA,

    2013-03-01

    Full Text Available The objective of this study was the preparation and characterization of high belite sulfoaluminate cement (HBSC from industrial residues. HBSC promises eco-friendly building materials with great mechanical performance at earlier ages than Ordinary Portland Cement (OPC. Preliminary results show the formation of main phase dicalcium silicate (C2S and ye’elimite (C4A3$ at 1250°C, as determined by X-ray diffraction (XRD, are promising. The formation of minerals in the clinker was analyzed by differential scanning calorimetry-thermogravimetry (DSC–TG. Likewise, Scanning electron microscope (SEM and XRD were used to carry out the analysis of the micro-structural and hydration products. The main HBSC hydration products, Ettringite and amorphous Al(OH3, were formed in the early stages; however, during the later stages, monosulfate and Strätlingite were formed. Isothermal conduction calorimetry measurements indicate that hydration properties of the cements are comparable to OPC; the total hydration heat after 3 days was 438 J/g. The optimum compressive strength values of the mortars after 1-, 3-, 7-, and 28-days were 24.9 MPa, 33.2 MPa, 35.6 MPa and 52.8 MPa which can meet the requirement of special structures.

  12. Bioactive and Hemocompatible Calcium Sulphoaluminate Cement

    OpenAIRE

    Acuña-Gutiérrez, Iván Omar; Escobedo-Bocardo, José Concepción; Almanza-Robles, José Manuel; Cortés-Hernández, Dora Alicia; Saldívar-Ramírez, Mirna María Guadalupe; Reséndiz-Hernández, Perla Janet; Zugasti-Cruz, Alejandro

    2015-01-01

    Calcium sulphoaluminate cement (CSAC) is an attractive candidate for biomedical applications due to its appropriate mechanical properties and high calcium content. In vitro bioactivity and hemocompatibility of calcium sulphoaluminate cement were assessed. The cement was prepared from a mixture of calcium sulphoaluminate (CSA) clinker, gypsum and water. Cement samples were immersed in a simulated body fluid (SBF) at 37 °C for different periods of time (7, 14 and 21 days). The analyses of these...

  13. Calcium Aluminate Cement Hydration Model

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    Matusinović, T.

    2011-01-01

    Full Text Available Calcium aluminate cement (AC is a very versatile special cement used for specific applications. As the hydration of AC is highly temperature dependent, yielding structurally different hydration products that continuously alter material properties, a good knowledge of thermal properties at early stages of hydration is essential. The kinetics of AC hydration is a complex process and the use of single mechanisms models cannot describe the rate of hydration during the whole stage.This paper examines the influence of temperature (ϑ=5–20 °C and water-to-cement mass ratio (mH /mAC = 0.4; 0.5 and 1.0 on hydration of commercial iron-rich AC ISTRA 40 (producer: Istra Cement, Pula, Croatia, which is a part of CALUCEM group, Figs 1–3. The flow rate of heat generation of cement pastes as a result of the hydration reactions was measured with differential microcalorimeter. Chemically bonded water in the hydrated cement samples was determined by thermo-gravimetry.Far less heat is liberated when cement and water come in contact for the first time, Fig. 1, than in the case for portland cement (PC. Higher water-to-cement ratio increases the heat evolved at later ages (Fig. 3 due to higher quantity of water available for hydration. A significant effect of the water-to-cement ratio on the hydration rate and hydration degree showed the importance of water as being the limiting reactant that slows down the reaction early. A simplified stoichiometric model of early age AC hydration (eq. (8 based on reaction schemes of principal minerals, nominally CA, C12A7 and C4AF (Table 1, was employed. Hydration kinetics after the induction period (ϑ < 20 °C had been successfully described (Fig. 4 and Table 2 by a proposed model (eq. (23 which simultaneously comprised three main mechanisms: nucleation and growth, interaction at phase boundary, and mass transfer. In the proposed kinetic model the nucleation and growth is proportional to the amount of reacted minerals (eq

  14. Nanostructure of Calcium Silicate Hydrates in Cements

    KAUST Repository

    Skinner, L. B.

    2010-05-11

    Calcium silicate hydrate (CSH) is the major volume phase in the matrix of Portland cement concrete. Total x-ray scattering measurements with synchrotron x rays on synthetic CSH(I) shows nanocrystalline ordering with a particle diameter of 3.5(5) nm, similar to a size-broadened 1.1 nm tobermorite crystal structure. The CSH component in hydrated tricalcium silicate is found to be similar to CSH(I). Only a slight bend and additional disorder within the CaO sheets is required to explain its nanocrystalline structure. © 2010 The American Physical Society.

  15. Development of a fully injectable calcium phosphate cement for ...

    Indian Academy of Sciences (India)

    A study on the development of a fully injectable calcium phosphate cement for orthopedic and dental applications is presented. The paper describes its characteristic properties including results of bio- compatibility studies. A conventional two-component calcium phosphate cement formulation (having a powder part ...

  16. Hydrophobic Calcium Carbonate for Cement Surface

    Directory of Open Access Journals (Sweden)

    Shashi B. Atla

    2017-12-01

    Full Text Available This report describes a novel way to generate a highly effective hydrophobic cement surface via a carbonation route using sodium stearate. Carbonation reaction was carried out at different temperatures to investigate the hydrophobicity and morphology of the calcium carbonate formed with this process. With increasing temperatures, the particles changed from irregular shapes to more uniform rod-like structures and then aggregated to form a plate-like formation. The contact angle against water was found to increase with increasing temperature; after 90 °C there was no further increase. The maximum contact angle of 129° was obtained at the temperature of 60 °C. It was also found that carbonation increased the micro hardness of the cement material. The micro hardness was found to be dependent on the morphology of the CaCO3 particles. The rod like structures which caused increased mineral filler produced a material with enhanced strength. The 13C cross polarization magic-angle spinning NMR spectra gave plausible explanation of the interaction of organic-inorganic moieties.

  17. Multimodal pore formation in calcium phosphate cements.

    Science.gov (United States)

    Lodoso-Torrecilla, Irene; van Gestel, Nicole A P; Diaz-Gomez, Luis; Grosfeld, Eline-Claire; Laperre, Kjell; Wolke, Joop G C; Smith, Brandon T; Arts, Jacobus J; Mikos, Antonios G; Jansen, John A; Hofmann, Sandra; van den Beucken, Jeroen J J P

    2017-09-23

    Calcium phosphate cements (CPCs) are commonly used as bone substitute materials. However, their slow degradation rate and lack of macroporosity hinders new bone formation. Poly(dl-lactic-co-glycolic acid) (PLGA) incorporation is of great interest as, upon degradation, produces acidic by-products that enhance CPC degradation. Yet, new bone formation is delayed until PLGA degradation occurs a few weeks after implantation. Therefore, the aim of this study was to accelerate the early stage pore formation within CPCs in vitro. With that purpose, we incorporated the water-soluble porogen sucrose at different weight percentages (10 or 20 wt %) to CPC and CPC/PLGA composites. The results revealed that incorporation of sucrose porogens increased mass loss within the first week of in vitro degradation in groups containing sucrose compared to control groups. After week 1, a further mass loss was observed related to PLGA and CPC degradation. Macroporosity analysis confirmed that macroporosity formation is influenced by the dissolution of sucrose at an early stage and by the degradation of PLGA and CPC at a later stage. We concluded that the combination of sucrose and PLGA porogens in CPC is a promising approach to promote early stage bone tissue ingrowth and complete replacement of CPC through multimodal pore formation. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2017. © 2017 Wiley Periodicals, Inc.

  18. Early age hydration of calcium sulfoaluminate (synthetic ye'elimite, ) in the presence of gypsum and varying amounts of calcium hydroxide

    KAUST Repository

    Hargis, Craig W.

    2013-06-01

    Suspensions of synthetic ye\\'elimite (C4A3S̄) in a saturated gypsum (CS̄H2) and calcium hydroxide (CH) solution were examined in-situ in a wet cell by soft X-ray transmission microscopy and ex-situ by scanning electron microscopy. The most voluminous hydration product observed was ettringite. Ettringite commonly displayed acicular, filiform, reticulated, and stellate crystal habits. Additionally, pastes with C 4A3S̄, 15% CS̄H2, and varying amounts of CH were prepared and examined with X-ray diffraction (XRD) and isothermal calorimetry. The XRD experiments showed that increasing CH content caused more solid solution (SO4 2 -/OH-) AFm phases to form at early ages (< 1 d) and more monosulfate to form at later ages (> 1 d). Calorimetry indicated that the increased production of solid solution AFm was accompanied with an increase in the initial (< 30 min) rate of heat evolution, and increasing CH generally reduced the time till the second maximum rate of heat evolution due to the formation of ettringite and monosulfate. © 2013 Elsevier Ltd.

  19. Effect of Fly Ash and Silica Fume on the Mechanical Properties of Cement Paste at Different Stages of Hydration

    Science.gov (United States)

    2015-08-10

    9 1.5.3 Calcium aluminates and sulfoaluminate phases...belite (C2S), tricalcium aluminate (C3A) and tetracalcium aluminoferrite (C4AF). Other chemicals that may exist are: sodium oxide (Na2O), potassium oxide...after one week of hardening. Tricalcium Aluminate : This compound doesn’t contribute much to the strength of the cement paste. However, it liberates a

  20. stabilization of ikpayongo laterite with cement and calcium carbide ...

    African Journals Online (AJOL)

    PROF EKWUEME

    Laterite obtained from Ikpayongo was stabilized with 2-10 % cement and 2-10 % Calcium Carbide waste, for use as pavement material. Atterberg's limits test, California bearing ratio (CBR) and unconfined compressive strength (UCS) tests were conducted on the natural laterite and the treated soil specimens. The plasticity ...

  1. Substitution of strontium for calcium in glass ionomer cements (Part ...

    African Journals Online (AJOL)

    Objectives: To investigate the effects of substituting strontium for calcium in fluoroaluminosilicate glass on the mechanical and ion-releasing properties of high-viscosity glass ionomer cements. Design: An exploratory, laboratory-based study. Setting: Dental biomaterials research laboratory, Dental Physical Sciences Unit, ...

  2. Stabilization of Ikpayongo laterite with cement and calcium carbide ...

    African Journals Online (AJOL)

    Laterite obtained from Ikpayongo was stabilized with 2-10 % cement and 2-10 % Calcium Carbide waste, for use as pavement material. Atterberg's limits test, California bearing ratio (CBR) and unconfined compressive strength (UCS) tests were conducted on the natural laterite and the treated soil specimens. The plasticity ...

  3. Evaluation of Calcium Silicate Cement Bond Strength after Using ...

    African Journals Online (AJOL)

    2018-01-24

    Jan 24, 2018 ... Objectives: To determine the effect of different gutta‑percha solvents. (chloroform, Endosolv E, orange oil, and eucalyptol) on the push‑out bond strength of calcium silicate cements (CSCs; white mineral trioxide aggregate. [WMTA]; capsule‑form mineral trioxide aggregate [CMTA], and Biodentine). Materials ...

  4. Calcium phosphate cements with strontium halides as radiopacifiers.

    Science.gov (United States)

    López, Alejandro; Montazerolghaem, Maryam; Engqvist, Håkan; Ott, Marjam Karlsson; Persson, Cecilia

    2014-02-01

    High radiopacity is required to monitor the delivery and positioning of injectable implants. Inorganic nonsoluble radiopacifiers are typically used in nondegradable bone cements; however, their usefulness in resorbable cements is limited due to their low solubility. Strontium halides, except strontium fluoride, are ionic water-soluble compounds that possess potential as radiopacifiers. In this study, we compare the radiopacity, mechanical properties, composition, and cytotoxicity of radiopaque brushite cements prepared with strontium fluoride (SrF2 ), strontium chloride (SrCl2 ·6H2 O), strontium bromide (SrBr2 ), or strontium iodide (SrI2 ). Brushite cements containing 10 wt % SrCl2 ·6H2 O, SrBr2 , or SrI2 exhibited equal to or higher radiopacity than commercial radiopaque cements. Furthermore, the brushite crystal lattice in cements that contained the ionic radiopacifiers was larger than in unmodified cements and in cements that contained SrF2 , indicating strontium substitution. Despite the fact that the strontium halides increased the solubility of the cements and affected their mechanical properties, calcium phosphate cements containing SrCl2 ·6H2 O, SrBr2 , and SrI2 showed no significant differences in Saos-2 cell viability and proliferation with respect to the control. Strontium halides: SrCl2 ·6H2 O, SrBr2 , and SrI2 may be potential candidates as radiopacifiers in resorbable biomaterials although their in vivo biocompatibility, when incorporated into injectable implants, is yet to be assessed. Copyright © 2013 Wiley Periodicals, Inc.

  5. Enhanced bioactivity of glass ionomer cement by incorporating calcium silicates.

    Science.gov (United States)

    Chen, Song; Cai, Yixiao; Engqvist, Håkan; Xia, Wei

    2016-01-01

    Glass ionomer cements (GIC) are known as a non-bioactive dental cement. During setting the GIC have an acidic pH, driven by the acrylic acid component. It is a challenge to make GIC alkaline without disturbing its mechanical properties. One strategy was to add slowly reacting systems with an alkaline pH. The aim of the present study is to investigate the possibility of forming a bioactive dental material based on the combination of glass ionomer cement and calcium silicates. Two types of GIC were used as control. Wollastonite (CS also denoted β-CaSiO3) or Mineral Trioxide Aggregate (MTA) was incorporated into the 2 types of GIC. The material formulations' setting time, compressive strength, pH and bioactivity were compared between modified GIC and GIC control. Apatite crystals were found on the surfaces of the modified cements but not on the control GIC. The compressive strength of the cement remained with the addition of 20% calcium silicate or 20% MTA after one day immersion. In addition, the compressive strength of GIC modified with 20% MTA had been increased during the 14 d immersion (p < 0 .05).

  6. Enhanced bioactivity of glass ionomer cement by incorporating calcium silicates

    Science.gov (United States)

    Chen, Song; Cai, Yixiao; Engqvist, Håkan; Xia, Wei

    2016-01-01

    Abstract Glass ionomer cements (GIC) are known as a non-bioactive dental cement. During setting the GIC have an acidic pH, driven by the acrylic acid component. It is a challenge to make GIC alkaline without disturbing its mechanical properties. One strategy was to add slowly reacting systems with an alkaline pH. The aim of the present study is to investigate the possibility of forming a bioactive dental material based on the combination of glass ionomer cement and calcium silicates. Two types of GIC were used as control. Wollastonite (CS also denoted β-CaSiO3) or Mineral Trioxide Aggregate (MTA) was incorporated into the 2 types of GIC. The material formulations’ setting time, compressive strength, pH and bioactivity were compared between modified GIC and GIC control. Apatite crystals were found on the surfaces of the modified cements but not on the control GIC. The compressive strength of the cement remained with the addition of 20% calcium silicate or 20% MTA after one day immersion. In addition, the compressive strength of GIC modified with 20% MTA had been increased during the 14 d immersion (p < 0 .05). PMID:26787304

  7. Simulating cement microstructural evolution during calcium leaching

    NARCIS (Netherlands)

    Patel, R.A.; Perko, J.; Jacques, D.; De Schutter, G.; Van Breugel, K.; Ye, G.

    2014-01-01

    Calcium leaching is one of the important degradation mechanisms causing dissolution of the crystalline phases such as, AFm, portlandite increasing capillary porosity. Further it leads to decalcification of an amorphous C-S-H phase causing increase in the gel porosity and in turn degrading the long

  8. In vivo Dentin Microhardness beneath a Calcium-Phosphate Cement

    Science.gov (United States)

    Bresciani, E.; Wagner, W.C.; Navarro, M.F.L.; Dickens, S.H.; Peters, M.C.

    2010-01-01

    A minimally invasive caries-removal technique preserves potentially repairable, caries-affected dentin. Mineral-releasing cements may promote remineralization of soft residual dentin. This study evaluated the in vivo remineralization capacity of resin-based calcium-phosphate cement (Ca-PO4) used for indirect pulp-capping. Permanent carious and sound teeth indicated for extraction were excavated and restored either with or without the Ca-PO4 base (control), followed by adhesive restoration. Study teeth were extracted after 3 months, followed by sectioning and in vitro microhardness analysis of the cavity floor to 115-µm depth. Caries-affected dentin that received acid conditioning prior to Ca-PO4 basing showed significantly increased Knoop hardness near the cavity floor. The non-etched group presented results similar to those of the non-treated group. Acid etching prior to cement application increased microhardness of residual dentin near the interface after 3 months in situ. PMID:20511564

  9. Hydration of calcium aluminate cement determined by thermal analysis

    Science.gov (United States)

    Scheinherrová, Lenka; Trník, Anton

    2017-07-01

    Calcium aluminate cements (CACs) are a very important type of non-Portland or special cements. Since they are considerably more expensive, they are not used as a simple substitute for Portland cement. Their structure allows them to achieve high compressive strength. They resist very well to high temperatures and temperature changes, or also to chemical attacks. The original motivation, why the CACs were developed, was the idea of finding new cement chemistries that would be more resistant to sulfate attack then Portland cements. Nowadays, the main usage of the CACs is in high temperatures applications. In this paper, we study the hydration of a CAC up to one year of age to control what happens in CACs structure during aging. The variety in the main products of hydration is studied using differential scanning calorimetry and thermogravimetry in the temperature range from 25 °C to 1000 °C with a heating rate of 5 °C/min in an argon atmosphere. The basic physical and mechanical properties are also determined.

  10. Short-fibre reinforcement of calcium phosphate bone cement.

    Science.gov (United States)

    Buchanan, F; Gallagher, L; Jack, V; Dunne, N

    2007-02-01

    Calcium phosphate cement (CPC) sets to form hydroxyapatite, a major component of mineral bone, and is gaining increasing interest in bone repair applications. However, concerns regarding its brittleness and tendency to fragment have limited its widespread use. In the present study, short-fibre reinforcement of an apatitic calcium phosphate has been investigated to improve the fracture behaviour. The fibres used were polypropylene (PP) fibres, 50 microm in diameter and reduced in length by cryogenic grinding. The compressive strength and fracture behaviour were examined. Fibre addition of up to 10 wt % had a significant effect on composite properties, with the energy absorbed during failure being significantly increased, although this tended to be accompanied with a slight drop in compressive strength. The fibre reinforcement mechanisms appeared to be crack bridging and fibre pull-out. The setting time of the CPC with fibre reinforcement was also investigated and was found to increase with fibre volume fraction.

  11. Injectable PLGA microsphere/calcium phosphate cements: physical properties and degradation characteristics.

    NARCIS (Netherlands)

    Habraken, W.J.E.M.; Wolke, J.G.C.; Mikos, A.G.; Jansen, J.A.

    2006-01-01

    Calcium phosphate (CaP) cements show an excellent biocompatibility and often have a high mechanical strength, but in general degrade relatively slow. To increase degradation rates, macropores can be introduced into the cement, e.g., by the inclusion of biodegradable microspheres into the cement. The

  12. Injectable calcium phosphate cement with PLGA, gelatin and PTMC microspheres in a rabbit femoral defect

    NARCIS (Netherlands)

    Liao, Hongbing; Walboomers, X. Frank; Habraken, Wouter J.E.M.; Zhang Zheng, Z.Z.; Li, Yubao; Grijpma, Dirk W.; Mikos, Antonios G.; Wolke, Joop G.C.; Jansen, John A.

    2011-01-01

    In this study, we investigated the in vivo degradation properties and tissue response towards injectable calcium phosphate cement (CPC) with no further addition, or calcium phosphate composite cement containing approximately 50 vol.% of microspheres. Three types of spheres were assessed, i.e.

  13. Gentamycin-impregnated calcium phosphate cement for calcaneal osteomyelitis: a case report.

    Science.gov (United States)

    Iwakura, Takashi; Lee, Sang Yang; Niikura, Takahiro; Miwa, Masahiko; Sakai, Yoshitada; Nishida, Kotaro; Kuroda, Ryosuke; Kurosaka, Masahiro

    2014-12-01

    We report a case of chronic calcaneal osteomyelitis in a diabetic patient who was successfully treated with radical debridement and gentamycin-impregnated calcium phosphate cement. At 1.5-year follow-up, the patient could walk without any assistance. Calcium phosphate cement is an effective local antibiotic delivery system and a biocompatible material for filling the debrided space to facilitate bone formation.

  14. Developement of calcium aluminate based systems for sludge cementation from radwaste decontamination

    OpenAIRE

    Martin, Isabelle

    2016-01-01

    Nuclear industry generated waste including radioactive wastes, which have different forms and origins. The wastes produced by reprocessing of nuclear fuel are characterized by important water content, by high pH and temperature sensitivity. The cementation in ettringite systems might be a promising solution to solidify radioactive wastes. Mixtures of Calcium Aluminate Cement (CAC) and calcium sulfate are planned to be used, instead of Ordinary Portland Cement (OPC), to form a significant amou...

  15. Variation of crystal structure of hydroxyapatite in calcium phosphate cement by the substitution of strontium ions.

    Science.gov (United States)

    Wang, Xiupeng; Ye, Jiandong

    2008-03-01

    New routes were used to introduce strontium into calcium phosphate cement in the present article. The study showed that by mixing 50 wt% amorphous calcium phosphate + amorphous strontium phosphate and 50 wt% dicalcium phosphate dihydrate, hydroxyapatite and Sr-hydroxyapatite precipitated separately in the hydrated cement; whereas, by mixing 50 wt% Sr- amorphous calcium phosphate and 50 wt% dicalcium phosphate dihydrate, strontium can be doped into hydroxyapatite lattice and increase the lattice dimensions and lattice volume. The strontium substituted calcium phosphate cement has potential for use in orthopedic surgeries.

  16. Molecular Dynamics Modeling of Hydrated Calcium-Silicate-Hydrate (CSH) Cement Molecular Structure

    Science.gov (United States)

    2014-08-30

    paste consisting of starting configuration of dry cement powder and water mixture by itself is a complex, multi-scale material system. Though...high pressure molecular structural behavior of the hydrated CSH. Portland cement in the powder form consists of four different major constituents...Tricalcium silicate (C3S), Di-Calcium silicate (C2S), Tri-Calcium aluminate (C3A), and Tetra calcium aluminoferrite (C4AF) [1]. Different mixture

  17. Calcium Phosphate Bone Cements Including Sugar Surfactants: Part One—Porosity, Setting Times and Compressive Strength

    Directory of Open Access Journals (Sweden)

    Juliette Fitremann

    2010-09-01

    Full Text Available Addition of sugar surfactants, sucrose fatty acid esters and alkylpolyglucosides, to calcium phosphate cement designed for bone reconstruction is described. Thanks to their surface activity and through their adsorption at the surface of the calcium phosphate particles, they both induced a strong increase in the porosity (quantified by Image Analysis and brought a very good workability. Other properties typically studied for these cements are reported, including setting times, compressive strength, cohesion in water, and effect of sterilization on these properties. The whole study brought good insight in the interest of adding these mild surfactants to improve several properties of the calcium phosphate cement, without impairing their function.

  18. Calcium Phosphate Bone Cements Including Sugar Surfactants: Part One-Porosity, Setting Times and Compressive Strength.

    Science.gov (United States)

    Bercier, Ariane; Gonçalves, Stéphane; Lignon, Olivier; Fitremann, Juliette

    2010-09-30

    Addition of sugar surfactants, sucrose fatty acid esters and alkylpolyglucosides, to calcium phosphate cement designed for bone reconstruction is described. Thanks to their surface activity and through their adsorption at the surface of the calcium phosphate particles, they both induced a strong increase in the porosity (quantified by Image Analysis) and brought a very good workability. Other properties typically studied for these cements are reported, including setting times, compressive strength, cohesion in water, and effect of sterilization on these properties. The whole study brought good insight in the interest of adding these mild surfactants to improve several properties of the calcium phosphate cement, without impairing their function.

  19. 3D Computational Simulation of Calcium Leaching in Cement Matrices

    Directory of Open Access Journals (Sweden)

    Gaitero, J. J.

    2014-12-01

    Full Text Available Calcium leaching is a degradation process consisting in progressive dissolution of the cement paste by migration of calcium atoms to the aggressive solution. It is therefore, a complex phenomenon involving several phases and dissolution and diffusion processes simultaneously. Along this work, a new computational scheme for the simulation of the degradation process in three dimensions was developed and tested. The toolkit was used to simulate accelerated calcium leaching by a 6M ammonium nitrate solution in cement matrices. The obtained outputs were the three dimensional representation of the matrix and the physicochemical properties of individual phases as a consequence of the degradation process. This not only makes it possible to study the evolution of such properties as a function of time but also as a function of the position within the matrix. The obtained results are in good agreement with experimental values of the elastic modulus in degraded and undegraded samples.El lixiviado de calcio es un proceso de degradación consistente en la disolución progresiva de la pasta de cemento por la migración de los átomos de calcio a la disolución agresiva. Se trata por tanto de un fenómeno complejo que involucra simultáneamente diferentes fases y procesos de disolución y difusión. En este trabajo se desarrolló y probó una nueva herramienta computacional para la simulación del proceso de degradación en tres dimensiones. Para ello se simuló el lixiviado de calcio acelerado provocado por una disolución de nitrato amónico 6M en matrices de cemento. Como resultado se obtuvieron la representación tridimensional de la matriz y las propiedades físico-químicas sus fases a lo largo del tiempo. Esto permitió estudiar la evolución de dichas propiedades a lo largo del proceso de degradación así como en función de su posición dentro de la matriz. Los resultados obtenidos coinciden con los valores experimentales del módulo elástico tanto

  20. Vibrational investigation of calcium-silicate cements for endodontics in simulated body fluids

    Science.gov (United States)

    Taddei, Paola; Modena, Enrico; Tinti, Anna; Siboni, Francesco; Prati, Carlo; Gandolfi, Maria Giovanna

    2011-05-01

    Calcium-silicate MTA (Mineral Trioxide Aggregate) cements have been recently developed for oral and endodontic surgery. This study was aimed at investigating commercial (White ProRoot MTA, White and Grey MTA-Angelus) and experimental (wTC-Bi) accelerated calcium-silicate cements with regards to composition, hydration products and bioactivity upon incubation for 1-28 days at 37 °C, in Dulbecco's Phosphate Buffered Saline (DPBS). Deposits on the surface of the cements and the composition changes during incubation were investigated by micro-Raman and ATR/FT-IR spectroscopy, and pH measurements. Vibrational techniques disclosed significant differences in composition among the unhydrated cements, which significantly affected the bioactivity as well as pH, and hydration products of the cements. After one day in DPBS, all the cements were covered by a more or less homogeneous layer of B-type carbonated apatite. The experimental cement maintained a high bioactivity, only slightly lower than the other cements and appears a valid alternative to commercial cements, in view of its adequate setting time properties. The bioactivity represents an essential property to favour bone healing and makes the calcium-silicate cements the gold standard materials for root-apical endodontic surgery.

  1. Effect of calcium carbonate on hardening, physicochemical properties, and in vitro degradation of injectable calcium phosphate cements.

    NARCIS (Netherlands)

    Sariibrahimoglu, K.; Leeuwenburgh, S.C.G.; Wolke, J.G.C.; Yubao, L.; Jansen, J.A.

    2012-01-01

    The main disadvantage of apatitic calcium phosphate cements (CPCs) is their slow degradation rate, which limits complete bone regeneration. Carbonate (CO(3)(2)(-)) is the common constituent of bone and it can be used to improve the degradability of the apatitic calcium phosphate ceramics. This study

  2. Investigating calcium polyphosphate addition to a conventional calcium phosphate cement for bone-interfacing applications

    Science.gov (United States)

    Krausher, Jennifer Lynn

    Calcium phosphate cements (CPCs) are of great interest in bone regeneration applications because of their biocompatibility and osteoconductivity, and as delivery vehicles for therapeutics; however, delivery applications have been limited by adverse interactions between therapeutics and the cement setting reaction. Amorphous calcium polyphosphate (CPP) yields a biodegradable material with a demonstrated drug delivery capacity following appropriate processing. The incorporation of drug-loaded CPP into a CPC is under consideration as a method of minimizing adverse interactions and extending drug release. This thesis represents the first investigation into the effects of CPP addition on the properties, setting and antibiotic release profile of a conventional apatitic calcium phosphate cement. As-made, gelled and vancomycin-loaded CPP particulate were added to the powder component of a conventional dicalcium phosphate/tetracalcium phosphate CPC. The setting behaviour, set properties and microstructure of the resulting CPP-CPCs were evaluated with setting time testing (Gilmore needle method), pH testing, mechanical testing, SEM imaging, XRD and FTIR analysis. In vitro degradation and elution behaviour were evaluated by monitoring calcium release (atomic absorbance spectroscopy), mechanical strength and vancomycin release (UV-visual spectrophotometry). CPP addition was found to increase the setting time, reduce the mechanical strength and inhibit the conversion of the CPC starting powders to the set apatitic phase. The most likely mechanism for the observed effect of CPP addition was the adsorption of polyphosphate chains on the particle surfaces, which would inhibit the dissolution of the starting powders and the conversion of apatite precursor phases to apatite, leading to reduced mechanical properties. The detrimental effects of CPP were reduced by limiting the CPP fraction to less than a few weight per cent and increasing the size of the CPP particulate. CPP

  3. Effect of phase composition of calcium silicate phosphate component on properties of brushite based composite cements

    Energy Technology Data Exchange (ETDEWEB)

    Sopcak, T., E-mail: tsopcak@imr.saske.sk [Institute of Materials Research of SAS, Watsonova 47, 04001 Kosice (Slovakia); Medvecky, L.; Giretova, M.; Stulajterova, R.; Durisin, J. [Institute of Materials Research of SAS, Watsonova 47, 04001 Kosice (Slovakia); Girman, V. [Institute of Physics, Faculty of Science, P. J. Šafárik University, Park Angelinum 9, 04001 Kosice (Slovakia); Faberova, M. [Institute of Materials Research of SAS, Watsonova 47, 04001 Kosice (Slovakia)

    2016-07-15

    The composite cement mixtures were prepared by mixing brushite (B) with, the amorphous hydrated calcium silicate phosphate (CSPH) or annealed calcium silicate phosphate (CSP composed of Si-saturated hydroxyapatite, wollastonite and silica) phases and water as liquid component. The contents of the silicate-phosphate phase in composites were 10.30 and 50 wt%. The significant effect of both the Ca/P ratio and different solubility of calcium silicate phosphate component in starting cement systems on setting time and phase composition of the final composite cements was demonstrated. The compressive strength of the set cements increased with the filler addition and the highest value (~ 48 MPa) exhibited the 50CSP/B cement composite. The final setting times of the composite cements decreased with the CSPH addition from about 25 to 17 min in 50CSHP/B and setting time of CSP/B composites was around 30 min. The higher content of silica in cements caused the precipitation of fine hydroxyapatite particles in the form of nanoneedles or thin plates perpendicularly oriented to sample surface. The analysis of in vitro cement cytotoxicity demonstrated the strong reduction in cytotoxicity of 10CSPH/B composite with time of cultivation (a low cytotoxicity after 9 days of culture) contrary to cements with higher calcium silicate-phosphate content. These results were attributed to the different surface topography of composite substrates and possible stimulation of cell proliferation by the slow continuously release of ions from 10CSPH/B cement. - Highlights: • Ca/P ratio and solubility of calcium silicate-phosphate components affect the self-setting properties of cements. • Strong relationship between the composite in vitro cytotoxicity and surface microtopography was demonstrated. • Plate-like morphology of coarser particles allowed cells to better adhere and proliferate as compared with nanoneedles.

  4. In vitro growth factor release from injectable calcium phosphate cements containing gelatin microspheres.

    NARCIS (Netherlands)

    Habraken, W.J.E.M.; Boerman, O.C.; Wolke, J.G.C.; Mikos, A.G.; Jansen, J.A.

    2009-01-01

    To improve the in vivo resorption of an injectable calcium phosphate cement (CPC) for bone tissue engineering purposes, in previous experiments macroporosity was introduced by the in situ degradation of incorporated gelatin microspheres. Gelatin microspheres are also suitable carriers for

  5. PLGA microsphere/calcium phosphate cement composites for tissue engineering: in vitro release and degradation characteristics.

    NARCIS (Netherlands)

    Habraken, W.J.E.M.; Wolke, J.G.C.; Mikos, A.G.; Jansen, J.A.

    2008-01-01

    Bone cements with biodegradable poly(lactic-co-glycolic acid) (PLGA) microspheres have already been proven to provide a macroporous calcium phosphate cement (CPC) during in situ microsphere degradation. Furthermore, in vitro/in vivo release studies with these PLGA microsphere/CPC composites

  6. Bone response to fast-degrading, injectable calcium phosphate cements containing PLGA microparticles

    NARCIS (Netherlands)

    Lanao, R.P.; Leeuwenburgh, S.C.G.; Wolke, J.G.C.; Jansen, J.A.

    2011-01-01

    Apatitic calcium phosphate cements (CPC) are frequently used to fill bone defects due to their favourable clinical handling and excellent bone response, but their lack of degradability inhibits complete bone regeneration. In order to render these injectable CaP cements biodegradable, hollow

  7. Trabecular bone response to injectable calcium phosphate (Ca-P) cement.

    NARCIS (Netherlands)

    Ooms, E.M.; Wolke, J.G.C.; Waerden, J.P.C.M. van der; Jansen, J.A.

    2002-01-01

    The aim of this study was to investigate the physicochemical, biological, and handling properties of a new developed calcium phosphate (Ca-P) cement when implanted in trabecular bone. Ca-P cement consisting of a powder and a liquid phase was implanted as a paste into femoral trabecular bone of goats

  8. Introduction of enzymatically degradable poly(trimethylene carbonate) microspheres into an injectable calcium phosphate cement

    NARCIS (Netherlands)

    Habraken, Wouter J. E. M.; Zhang, Zheng; Wolke, Joop G. C.; Grijpma, Dirk W.; Mikos, Antonios G.; Feijen, Jan; Jansen, John A.

    Poly(trimethylene carbonate) (PTMC) is an enzymatically degradable polyester with rubber-like properties. Introduction of this polymer into an injectable calcium phosphate bone cement can therefore be used to introduce macroporosity into the cement for tissue engineering purposes as well as to

  9. Molecular mechanism of crystallization impacting calcium phosphate cements

    Energy Technology Data Exchange (ETDEWEB)

    Giocondi, J L; El-Dasher, B S; Nancollas, G H; Orme, C A

    2009-05-31

    In summary, SPM data has shown that (1) Mg inhibits growth on all steps but relatively high Mg/Ca ratios are needed. Extracting the mechanism of interaction requires more modeling of the kinetic data, but step morphology is consistent with incorporation. (2) Citrate has several effects depending on the citrate/Ca ratio. At the lowest concentrations, citrate increases the step free energy without altering the step kinetics; at higher concentrations, the polar step is slowed. (3) Oxalate also slows the polar step but additionally stabilizes a new facet, with a [100]{sub Cc} step. (4) Etidronate has the greatest kinetic impact of the molecules studied. At 7{micro}M concentrations, the polar step slows by 60% and a new polar step appears. However, at the same time the [10-1]{sub Cc} increases by 67%. It should be noted that all of these molecules complex calcium and can effect kinetics by altering the solution supersaturation or the Ca to HPO{sub 4}{sup 2-} ratio. For the SPM data shown, this effect was corrected for to distinguish the effect of the molecule at the crystal surface from the effect of the molecule on the solution speciation. The goal of this paper is to draw connections between fundamental studies of atomic step motion and potential strategies for materials processing. It is not our intent to promote the utility of SPM for investigating processes in cement dynamics. The conditions are spectacularly different in many ways. The data shown in this paper are fairly close to equilibrium (S=1.6) whereas the nucleation of cements is initiated at supersaturation ratios in the thousands to millions. Of course, after the initial nucleation phase, the growth will occur at more modest supersaturations and as the cement evolves towards equilibrium certainly some of the growth will occur in regimes such as shown here. In addition to the difference in supersaturation, cements tend to have lower additive to calcium ratios. As an example, the additive to Ca ratio is

  10. Calcium Phosphate Bone Cements Including Sugar Surfactants: Part Two—Injectability, Adhesive Properties and Biocompatibility

    OpenAIRE

    Fabienne Briand-Mesange; Stéphane Gonçalves; Helène Autefage; Ariane Bercier; Olivier Lignon; Juliette Fitremann

    2010-01-01

    Addition of sugar surfactants, sucrose fatty acid esters and alkylpolyglucosides to a calcium phosphate cement, designed for bone reconstruction, is described. Thanks to their adsorption at the surface of the calcium phosphate particles, the sugar surfactants allowed a full injectability and brought a very good workability. Injectability was measured by monitoring force-distance curves. With some of the selected sugar surfactants adhesive properties of the cement pastes were also observed, wh...

  11. Calcium Phosphate Bone Cements Including Sugar Surfactants: Part One?Porosity, Setting Times and Compressive Strength

    OpenAIRE

    Juliette Fitremann; Ariane Bercier; Olivier Lignon; Stéphane Gonçalves

    2010-01-01

    Addition of sugar surfactants, sucrose fatty acid esters and alkylpolyglucosides, to calcium phosphate cement designed for bone reconstruction is described. Thanks to their surface activity and through their adsorption at the surface of the calcium phosphate particles, they both induced a strong increase in the porosity (quantified by Image Analysis) and brought a very good workability. Other properties typically studied for these cements are reported, including setting times, compressive str...

  12. Effect of polymer molecular weight on the bone biological activity of biodegradable polymer/calcium phosphate cement composites.

    NARCIS (Netherlands)

    Bodde, E.W.H.; Habraken, W.J.E.M.; Mikos, A.G.; Spauwen, P.H.M.; Jansen, J.A.

    2009-01-01

    Previous studies demonstrated that the addition of biodegradable polymer microparticles to calcium phosphate (CaP) cement improves the cement's degradative behavior without affecting its handling characteristics, especially its injectability and moldability. We investigated the influence of

  13. BLENDED CALCIUM ALUMINATE-CALCIUM SULFATE CEMENT-BASED GROUT FOR P-REACTOR VESSEL IN-SITU DECOMMISSIONING

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C.; Stefanko, D.

    2011-03-10

    The objective of this report is to document laboratory testing of blended calcium aluminate - calcium hemihydrate grouts for P-Reactor vessel in-situ decommissioning. Blended calcium aluminate - calcium hemihydrate cement-based grout was identified as candidate material for filling (physically stabilizing) the 105-P Reactor vessel (RV) because it is less alkaline than portland cement-based grout which has a pH greater than 12.4. In addition, blended calcium aluminate - calcium hemihydrate cement compositions can be formulated such that the primary cementitious phase is a stable crystalline material. A less alkaline material (pH {<=} 10.5) was desired to address a potential materials compatibility issue caused by corrosion of aluminum metal in highly alkaline environments such as that encountered in portland cement grouts [Wiersma, 2009a and b, Wiersma, 2010, and Serrato and Langton, 2010]. Information concerning access points into the P-Reactor vessel and amount of aluminum metal in the vessel is provided elsewhere [Griffin, 2010, Stefanko, 2009 and Wiersma, 2009 and 2010, Bobbitt, 2010, respectively]. Radiolysis calculations are also provided in a separate document [Reyes-Jimenez, 2010].

  14. Hydration characteristics of calcium silicate cements with alternative radiopacifiers used as root-end filling materials.

    Science.gov (United States)

    Camilleri, Josette

    2010-03-01

    Mineral trioxide aggregate (MTA) is composed of calcium silicate cement and bismuth oxide added for radiopacity. The bismuth oxide in MTA has been reported to have a deleterious effect on the physical and chemical properties of the hydrated material. This study aimed to investigate the hydration mechanism of calcium silicate cement loaded with different radiopacifiers for use as a root-end filling material. Calcium silicate cement loaded with barium sulfate, gold, or silver/tin alloy was hydrated, and paste microstructure was assessed after 30 days. In addition, atomic ratio plots of Al/Ca versus Si/Ca and S/Ca and Al/Ca were drawn, and X-ray energy dispersive analysis of the hydration products was performed to assess for inclusion of heavy metals. The leachate produced from the cements after storage of the cements in water for 28 days and the leaching of the radiopacifiers in an alkaline solution was assessed by using inductively coupled plasma. The hydrated calcium silicate cement was composed of calcium silicate hydrate, calcium hydroxide, ettringite, and monosulfate. Unhydrated cement particles were few. No heavy metals were detected in the calcium silicate hydrate except for the bismuth in MTA. Calcium was leached out early in large quantities that reduced with time. The barium and bismuth were leached in increasing amounts. Copper was the most soluble in alkaline solution followed by bismuth and barium in smaller amounts. The bismuth oxide can be replaced by other radiopacifiers that do not affect the hydration mechanism of the resultant material. Copyright (c) 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  15. Fabrications of zinc-releasing biocement combining zinc calcium phosphate to calcium phosphate cement.

    Science.gov (United States)

    Horiuchi, Shinya; Hiasa, Masahiro; Yasue, Akihiro; Sekine, Kazumitsu; Hamada, Kenichi; Asaoka, Kenzo; Tanaka, Eiji

    2014-01-01

    Recently, zinc-releasing bioceramics have been the focus of much attention owing to their bone-forming ability. Thus, some types of zinc-containing calcium phosphate (e.g., zinc-doped tricalcium phosphate and zinc-substituted hydroxyapatite) are examined and their osteoblastic cell responses determined. In this investigation, we studied the effects of zinc calcium phosphate (ZCP) derived from zinc phosphate incorporated into calcium phosphate cement (CPC) in terms of its setting reaction and MC3T3-E1 osteoblast-like cell responses. Compositional analysis by powder X-ray diffraction analysis revealed that HAP crystals were precipitated in the CPC containing 10 or 30wt% ZCP after successfully hardening. However, the crystal growth observed by scanning electron microscopy was delayed in the presence of additional ZCP. These findings indicate that the additional zinc inhibits crystal growth and the conversion of CPC to the HAP crystals. The proliferation of the cells and alkaline phosphatase (ALP) activity were enhanced when 10wt% ZCP was added to CPC. Taken together, ZCP added CPC at an appropriate fraction has a potent promotional effect on bone substitute biomaterials. © 2013 Elsevier Ltd. All rights reserved.

  16. Physical characteristics, antimicrobial and odontogenesis potentials of calcium silicate cement containing hinokitiol.

    Science.gov (United States)

    Huang, Ming-Hsien; Shen, Yu-Fang; Hsu, Tuan-Ti; Huang, Tsui-Hsien; Shie, Ming-You

    2016-08-01

    Hinokitiol is a natural material and it has antibacterial and anti-inflammatory effects. The purpose of this study was to evaluate the material characterization, cell viability, antibacterial and anti-inflammatory abilities of the hinokitiol-modified calcium silicate (CS) cement as a root end filling material. The setting times, diametral tensile strength (DTS) values and XRD patterns of CS cements with 0-10mM hinokitiol were examined. Then, the antibacterial effect and the expression levels of cyclooxygenase 2 (COX-2) and interleukin-1 (IL-1) of the hinokitiol-modified CS cements were evaluated. Furthermore, the cytocompatibility, the expression levels of the markers of odontoblastic differentiation, mineralized nodule formation and calcium deposition of human dental pulp cells (hDPCs) cultured on hinokitiol-modified CS cements were determined. The hinokitiol-modified CS cements had better antibacterial and anti-inflammatory abilities and cytocompatibility than non-modified CS cements. Otherwise, the hinokitiol-modified CS cements had suitable setting times and better odontoblastic potential of hDPCs. Previous report pointed out that the root-end filling materials may induce inflammatory cytokines reaction. In our study, hinokitiol-modified CS cements not only inhibited the expression level of inflammatory cytokines, but also had better cytocompatibility, antimicrobial properties and active ability of odontoblastic differentiation of hDPCs. Therefore, the hinokitiol-modified CS cement may be a potential root end filling material for clinic. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Retentive Strength of Orthodontic Bands Cemented with Amorphous Calcium Phosphate-Modified Glass Ionomer Cement: An In-Vitro Study

    Directory of Open Access Journals (Sweden)

    Farzin Heravi

    2017-02-01

    Full Text Available Objectives: The aim of this study was to evaluate and compare the retentive strength of orthodontic bands cemented with amorphous calcium phosphate (ACP-containing and conventional glass ionomer cements (GICs. Materials and Methods: One-hundred-and-twenty mandibular third molars were embedded in acrylic resin blocks with the buccal surface of crowns perpendicular to the base of the mold. The teeth were randomly divided into four groups containing 30 teeth each. Groups 1 and 3 were cemented using conventional GIC and groups 2 and 4 were cemented using ACP-containing orthodontic cement. Groups 1 and 2 without thermocycling, and groups 3 and 4 after thermocycling (5000 cycles, 5° to 55°C were tested for retentive strength using a universal testing machine (crosshead speed of 1mm/minute. Two-way ANOVA was performed to compare the retentive strength of the groups.Results: The highest retentive strength belonged to group 1, and it was significantly higher than that of group 2 (P<0.001 and group 3 (P=0.02. The mean strength for group 2 was significantly lower than that of group 1 (P<0.001 and group 4 (P=0.04. Conclusions: Although retentive strength decreased when ACP was added to GIC, the retentive strength of the samples cemented by ACP-containing GIC was remarkably high after thermocycling. It seems that in the oral cavity, ACP-containing GIC provides sufficient strength to endure forces applied on posterior teeth.Keywords: Glass Ionomer Cements; Amorphous Calcium Phosphate; Retention

  18. SYNTHESIS OF EXPANDER TO PREVENT CONTRACTION OF CEMENT STONE

    Directory of Open Access Journals (Sweden)

    Elenova Aurika Almazovna

    2017-03-01

    Full Text Available This article contains the results of studies of the use of additives containing crystallization components significantly affecting the curing of cement, improving the structure of cement stone and concrete. The crystalline component is obtained using the rotary-pulse unit, which provides not only the grinding of agents, but their interaction with each other as well in order to accelerate the hydration and structure formation in cement stone. The degree, and kinetics of hydration, the composition of hydrated phases, the structure of the additives and cement stone was studied using the following methods: x-ray diffraction (XRD, differential thermal analysis (DTA, scanning electron microscope (SEM. Mechanical properties of cement were determined by standard methods and techniques. The expander produced by means of hydrodynamic activation of the sulfoaluminate clinker (SAC consists of ettringite and hydrated calcium silicates, which are characterized by high dispersion rate (less than 10 µm and reactivity as the seed for the crystallization of hydrated compounds. The introduction of the ultrafine additives of the crystalline SAC (within 1-5% was discovered to cause expansion of the cement stone. Implementation of the additives increases cement hydration and contributes to the formation of active centers of crystallization that lead to the fast formation of ettringite, hydrated calcium aluminates and calcium silicates. The activated crystalline additive provides for significant reduction of porosity, initial curing, and high strength of cement stone. In addition, the additive is an expansive component, forming needle-like crystals of ettringite during hydration. These microcrystals grow in the capillaries of cement stone, filling them, and create conditions for improving the crack resistance of cement concrete.

  19. Incorporation of Collagen in Calcium Phosphate Cements for Controlling Osseointegration

    Directory of Open Access Journals (Sweden)

    Ming-Hsien Hu

    2017-08-01

    Full Text Available In this study, we investigated the effect of supplementing a non-dispersive dicalcium phosphate-rich calcium phosphate bone cement (DCP-rich CPC with type I collagen on in vitro cellular activities and its performance as a bone graft material. Varying amounts of type I collagen were added during the preparation of the DCP-rich CPC. In vitro cell adhesion, morphology, viability, and alkaline phosphatase (ALP activity were evaluated using progenitor bone cells. Bone graft performance was evaluated via a rat posterolateral lumbar fusion model and osteointegration of the implant. New bone formations in the restorative sites were assessed by micro-computed tomography (micro-CT and histological analysis. We found that the incorporation of collagen into the DCP-rich CPC was associated with increased cell adhesion, cell viability, and ALP activity in vitro. The spinal fusion model revealed a significant increase in bone regeneration. Additionally, better osseointegration was observed between the host bone and graft with the DCP-rich CPC supplemented with collagen than with the collagen-free DCP-rich CPC control graft. Furthermore, compared to the control graft, the results of micro-CT showed that a smaller amount of residual material was observed with the collagen-containing DCP-rich CPC graft compared with the control graft, which suggests the collagen supplement enhanced new bone formation. Of the different mixtures evaluated in this study (0.8 g DCP-rich CPC supplemented with 0.1, 0.2, and 0.4 mL type I collagen, respectively, DCP-rich CPC supplemented with 0.4 mL collagen led to the highest level of osteogenesis. Our results suggest that the DCP-rich CPC supplemented with collagen has potential to be used as an effective bone graft material in spinal surgery.

  20. Calcium phosphate cement augmentation of cancellous bone screws can compensate for the absence of cortical fixation.

    Science.gov (United States)

    Stadelmann, Vincent A; Bretton, Elise; Terrier, Alexandre; Procter, Philip; Pioletti, Dominique P

    2010-11-16

    An obvious means to improve the fixation of a cancellous bone screw is to augment the surrounding bone with cement. Previous studies have shown that bone augmentation with Calcium Phosphate (CaP) cement significantly improves screw fixation. Nevertheless, quantitative data about the optimal distribution of CaP cement is not available. The present study aims to show the effect of cement distribution on the screw fixation strength for various cortical thicknesses and to determine the conditions at which cement augmentation can compensate for the absence of cortical fixation in osteoporotic bone. In this study, artificial bone materials were used to mimic osteoporotic cancellous bone and cortical bone of varying thickness. These bone constructs were used to test the fixation strength of cancellous bone screws in different cortical thicknesses and different cement augmentation depths. The cement distribution was measured with microCT. The maximum pullout force was measured experimentally. The microCT analysis revealed a pseudo-conic shape distribution of the cement around the screws. While the maximum pullout strength of the screws in the artificial bone only was 30±7N, it could increase up to approximately 1000N under optimal conditions. Cement augmentation significantly increased pullout force in all cases. The effect of cortical thickness on pullout force was reduced with increased cement augmentation depth. Indeed, cement augmentation without cortical fixation increased pullout forces over that of screws without cement augmentation but with cortical fixation. Since cement augmentation significantly increased pullout force in all cases, we conclude that the loss of cortical fixation can be compensated by cement augmentation. Copyright © 2010 Elsevier Ltd. All rights reserved.

  1. Characterization of modified calcium-silicate cements exposed to acidic environment

    Energy Technology Data Exchange (ETDEWEB)

    Camilleri, Josette, E-mail: josette.camilleri@um.edu.mt

    2011-01-15

    Portland cement which is used as a binder in concrete in the construction industry has been developed into a biomaterial. It is marketed as mineral trioxide aggregate and is used in dentistry. This material has been reported to be very biocompatible and thus its use has diversified. The extended use of this material has led to developments of newer versions with improved physical properties. The aim of this study was to evaluate the effect of acidic environments found in the oral cavity on fast setting calcium silicate cements with improved physical properties using a combination of techniques. Two fast setting calcium silicate cements (CSA and CFA) and two cement composites (CSAG and CFAG) were assessed by subjecting the materials to lactic acid/sodium lactate buffer gel for a period of 28 days. At weekly intervals the materials were viewed under the tandem scanning confocal microscope (TSM), and scanning electron microscope (SEM). The two prototype cements exhibited changes in their internal chemistry with no changes in surface characteristics. Since the changes observed were mostly sub-surface evaluation of surface characteristics of cement may not be sufficient in the determination of chemical changes occurring. - Research Highlights: {yields} An acidic environment affects modified fast setting calcium silicate-based cements. {yields} No surface changes are observed in acidic environment. {yields} An acidic environment causes sub-surface changes in the material chemistry which are only visible in fractured specimens. {yields} A combination of techniques is necessary in order to evaluate the chemical changes occurring.

  2. Incorporation of bitumen and calcium silicate in cement and lime stabilized soil blocks

    Science.gov (United States)

    Kwan, W. H.; Cheah, C. B.; Ramli, M.; Al-Sakkaf, Y. K.

    2017-04-01

    Providing affordable housing is the most critical problem in many of the developing countries. Using earth materials in building construction is one of the feasible methods to address this issue and it can be a way towards sustainable construction as well. However, the published information on the stabilized soil blocks is limited. Therefore, the present study is conducted to examine the characterization of the soils and engineering properties of the stabilized soil blocks. Four types of stabilizer were used in the study, namely; cement, slaked lime, bitumen emulsion and calcium silicate. Cement and slaked lime were added at different percentages in the range of 5% to 15%, with interval of 2.5%. The percentage was determined based on weight of soil. Meanwhile, bitumen emulsion and calcium silicate were incorporated at various percentages together with 10% of cement. Dosage of bitumen emulsion is in the range of 2% to 10% at interval of 2% while calcium silicate was incorporated at 0.50%, 0.75%, 1.00%, 1.25%, 1.50% and 2.00%. Results show that cement is the most viable stabilizer for the soil block among all stabilizers in this study. The bulk density, optimum moisture content and compressive strengths were increased with the increasing cement content. The most suitable cement content was 10% added at moisture content of 12%. Lime, bitumen and calcium contents were recommended at 5.0%, 6.0% and 1.25%, respectively.

  3. Processing and Properties of Chemically Derived Calcium Silicate Cements

    Science.gov (United States)

    1992-02-27

    alone due to the fineness of the powder and the stiffness of the dough which resulted after shear mixing, characterisitics consistent with the large...cements. The lamination of the polymer in the isostatically pressed cement samples could be the reason for high toughness results. Summary and

  4. Effect of modified compound calcium phosphate cement on the differentiation and osteogenesis of bone mesenchymal stem cells.

    Science.gov (United States)

    Zeng, Jican; Lin, Jiazhong; Yao, Guanfeng; Kong, Kangmei; Wang, Xinjia

    2017-06-29

    The aim of this study is to evaluate the effect of self-invented compound calcium phosphate cement upon the proliferation and osteogenesis of bone mesenchymal stem cells (BMSCs). Four groups including traditional calcium phosphate cement, modified calcium phosphate cement, modified calcium phosphate cement plus bone morphogenetic protein (BMP), and control groups were established. The cell proliferation curve was delineated by MTT. The activity of BMSCs to synthesize alkaline phosphatase (AKP) was evaluated. The growth and invasion of BMSCs were observed. The expression levels of aggrecan, collagen I, collagen II, AKP, and OSX messenger RNA (mRNA) were measured by using RT-PCR. Compared with other groups, the BMSCs in the modified calcium phosphate cement group presented with loose microstructure and the BMSCs closely attached to the vector margin. At 7 days after co-culture, the expression of AKP in the modified calcium phosphate cement plus BMP group was significantly upregulated compared with those in other groups. In the modified calcium phosphate cement group, the BMSCs properly proliferated on the surface of bone cement and invaded into the cement space. At 10 days, the expression levels of aggrecan, collagen I, collagen II, AKP, and OSX mRNA in the modified calcium phosphate cement and modified calcium phosphate cement plus BMP groups were significantly upregulated than those in other groups. Modified compound calcium phosphate cement possesses excellent biocompatibility and osteogenic induction ability. Loose microstructure and large pore size create a favorable environment for BMSCs proliferation and vascular invasion, as an ideal vector for releasing BMP cytokines to mediate the differentiation and osteogenesis of BMSCs.

  5. The effects of excess calcium on the handling and mechanical properties of hydrothermal derived calcium phosphate bone cement

    Science.gov (United States)

    Razali, N. N.; Sukardi, M. A.; Sopyan, I.; Mel, M.; Salleh, H. M.; Rahman, M. M.

    2018-01-01

    The objective of this study is to determine the effects of excess calcium on the handling and mechanical properties of hydrothermal derived calcium phosphate cement (CPC) for bone filling applications. Hydroxyapatite powder was synthesized via hydrothermal method using calcium oxide, CaO and ammonium dihydrogen phosphate, NH4H2PO4 as the calcium and phosphorus precursors respectively. The effects of calcium excess were evaluated by varying the CaO content at 0, 5 and 15 mole %. The precursors were then refluxed in distilled water at 90-100°C and dried overnight until the calcium phosphate powder was formed. CPC was then produced by mixing the synthesized powder with distilled water at the powder-to-liquid (P/L) ratio of 1.5. The result from the morphological properties of CPC shows the increase in agglomeration and particles size with 5 mole % of calcium excess but decreased with 15 mole % of calcium excess in CPC. This result was in agreement with the compressive strength result where the CPC increased its strength with 5 mole % of calcium excess but reduced with 15 mole % of calcium excess. The excess in calcium precursor also significantly improved the setting time but reduced the injectability of CPC.

  6. Antiwashout behavior of calcium phosphate cement incorporated with Poly(ethylene glycol)

    Science.gov (United States)

    Hablee, S.; Sopyan, I.; Mel, M.; Salleh, H. M.; Rahman, M. M.

    2018-01-01

    The effect of powder-to-liquid ratio and addition of poly(ethylene glycol) on the antiwashout behavior of calcium phosphate cement has been investigated. Calcium hydroxide, Ca(OH)2, and diammonium hydrogen phosphate, (NH4)2HPO4, were used as precursors with distilled water as the solvent in the wet chemical precipitation synthesis of hydroxyapatite powder. Cement paste was prepared by mixing the as-synthesized powder with distilled water at certain ratios, varied at 1.0, 1.3, 1.5 and 1.6. Poly(ethylene glycol) was added into distilled water, varied at 1, 2, 3, 4 and 5 wt% using the powder-to-liquid ratio of 1.3. The antiwashout properties of the cement has been investigated by soaking in Ringer’s solution for 3 and 7 days. The evolution of compressive strength of calcium phosphate cement before and after soaking have been determined. After 7 days soaking, the strength of the cement increased by 94.4%, 2.98%, 11.39% and 111.29% for powder-to-liquid ratios 1.0, 1.3, 1.5 and 1.6 respectively. The addition of poly(ethylene glycol) up to 3% shows an increase in strength after 7 days soaking, with 57.75%, 16.4% and 19.97% increase for 1, 2 and 3% poly(ethylene glycol) contents respectively. The calcium phosphate cement produced in this current study shows excellent antiwashout behavior since no cement dissolution happened and the compressive strength of the cement increased with soaking time throughout 7 days soaking in Ringer’s solution.

  7. Calcium Phosphate Bone Cements Including Sugar Surfactants: Part Two—Injectability, Adhesive Properties and Biocompatibility

    Directory of Open Access Journals (Sweden)

    Fabienne Briand-Mesange

    2010-12-01

    Full Text Available Addition of sugar surfactants, sucrose fatty acid esters and alkylpolyglucosides to a calcium phosphate cement, designed for bone reconstruction, is described. Thanks to their adsorption at the surface of the calcium phosphate particles, the sugar surfactants allowed a full injectability and brought a very good workability. Injectability was measured by monitoring force-distance curves. With some of the selected sugar surfactants adhesive properties of the cement pastes were also observed, which were measured by tack tests. Finally, some properties related to biological applications are described, including gentamicine release and osteoblast viability experiments. The whole study demonstrates that addition of these mild surfactants improved several properties of the calcium phosphate cement, without impairing function.

  8. Calcium Phosphate Bone Cements Including Sugar Surfactants: Part Two-Injectability, Adhesive Properties and Biocompatibility.

    Science.gov (United States)

    Bercier, Ariane; Gonçalves, Stéphane; Autefage, Helène; Briand-Mesange, Fabienne; Lignon, Olivier; Fitremann, Juliette

    2010-12-02

    Addition of sugar surfactants, sucrose fatty acid esters and alkylpolyglucosides to a calcium phosphate cement, designed for bone reconstruction, is described. Thanks to their adsorption at the surface of the calcium phosphate particles, the sugar surfactants allowed a full injectability and brought a very good workability. Injectability was measured by monitoring force-distance curves. With some of the selected sugar surfactants adhesive properties of the cement pastes were also observed, which were measured by tack tests. Finally, some properties related to biological applications are described, including gentamicine release and osteoblast viability experiments. The whole study demonstrates that addition of these mild surfactants improved several properties of the calcium phosphate cement, without impairing function.

  9. Calcium aluminate cement hydration in a high alkalinity environment

    Directory of Open Access Journals (Sweden)

    Palomo, Á.

    2009-03-01

    Full Text Available The present paper forms part of a broader research project that aims primarily to devise new cementitious products via the alkali activation of silico-aluminous materials. This work addresses the possibility of using small percentages of calcium aluminate cement (CAC as a source of reactive aluminium. For this reason, a preliminary review was needed of the behaviour of CACs in highly alkaline media (2, 8 and 12M NaOH solutions. Two, 28- and 180-day mechanical strength was determined and the reaction products were characterized with XRD and FTIR. The water-hydrated CAC was used as the control.The results obtained showed that CAC hardening took place much more slowly in highly alkaline media than in water. Nonetheless, the 28-day compressive strength obtained, ≥80MPa. As main reaction products, to ambient temperature and from the two days of cured, cubic aluminate C3AH6, and AH3 polymorphs are formed, instead of the usual hexagonal aluminatos (CAH10 and C2AH8 that are formed in the normal hydrate with water.El presente trabajo forma parte de una amplia investigación cuyo objetivo principal es el de elaborar nuevos materiales con propiedades cementantes mediante la activación alcalina de materiales de naturaleza silito-aluminosa. En estos estudios se contempla la posibilidad de utilizar pequeños porcentajes de cemento de aluminato de calcio (CAC como fuente de aluminio reactivo. Por ello inicialmente se ha estudiado el comportamiento de los CAC en medios fuertemente alcalinos (disoluciones de NaOH 2M, 8M y 12M. Se determinaron las resistencias mecánicas a 2, 28 y 180 días y se realizó una caracterización de los productos de reacción formados por DRX, FTIR. Como sistema de referencia se consideró la hidratación del CAC con agua.Los resultados obtenidos muestran que en medios fuertemente alcalinos se retrasan los procesos de rápido endurecimiento de CAC con agua. No obstante a 28 días se obtienen valores de resistencia a compresión

  10. Correlative micro-Raman/EPMA analysis of the hydraulic calcium silicate cement interface with dentin.

    Science.gov (United States)

    Li, Xin; Pongprueksa, Pong; Van Landuyt, Kirsten; Chen, Zhi; Pedano, Mariano; Van Meerbeek, Bart; De Munck, Jan

    2016-09-01

    This study aims to characterize the chemical interplay of hydraulic calcium silicate cements at dentin. Class I cavities were prepared in non-carious human third molars and filled with Biodentine (Septodont) or ProRoot MTA (Dentsply). After 1-day, 1-week, and 1-month Dulbecco's phosphate-buffered saline (DPBS) storage, the specimens were cross-sectioned perpendicular to the cement-dentin interface. The interfaces were evaluated using micro-Raman (μRaman) spectroscopy and at a higher spatial resolution using field emission gun electron probe microanalysis (Feg-SEM/EPMA). μRaman spectroscopy revealed the formation of a transition zone at the interface of both Biodentine (Septodont) and ProRoot MTA (Dentsply) with dentin, having an average thickness of, respectively, 7.5 ± 4.2 and 6.2 ± 5.4 μm, which however was not statistically different. No difference in interfacial ultrastructure and chemistry was found using μRaman spectroscopy between 1 day, 1 week, and 1 month DPBS-stored specimens. The observation of a transition zone at the cement-dentin interfaces contrasts with the EPMA data that revealed a sharper transition from cement to dentin. Again, no difference in interfacial ultrastructure and chemistry was found for different storage periods, with the exception of one 1 month DPBS-stored specimen prepared using Biodentine (Septodont). More specifically, EPMA revealed a gap of about 10-μm wide in the latter specimen that was filled up with newly formed calcium phosphate depositions. Up to 1 month, the interaction of hydraulic calcium silicate cements investigated did not reveal ultrastructural or chemical changes at unaffected dentin with the exception of a calcium phosphate gap-filling property. Hydraulic calcium silicate cements were found to fill gaps by calcium phosphate deposition, however, without conducting chemical changes to the adjacent dentin.

  11. CALCIUM ORTHOPHOSPHATES HYDRATES: FORMATION, STABILITY AND INFLUENCE ON STANDARD PROPERTIES OF PORTLAND CEMENT

    Directory of Open Access Journals (Sweden)

    Kaziliunas A.

    2013-12-01

    Full Text Available Preparation of phosphogypsum to produce the binders requires a much higher input than preparation of natural gypsum stone. This makes it uncompetitive material. The investigations presented therein are meant to reduce this input by looking for the ways of rendering impurities harmless. Soluble acid orthophosphates are the main harmful impurity of phosphogypsum. The studies show that dry insoluble calcium orthophosphates hydrates (1.09 % and 2.18 % P2O5 in gypsum have little effect on W/C, setting times and soundness of Portland cement pastes. Insoluble calcium orthophosphates hydrates {CaHPO4∙2H2O, Ca8(HPO42(PO44∙5H2O and Ca9(HPO4(PO45(OH∙4H2O} formed in acidic medium (pH = 4.2 - 5.9 have been destroyed in alkaline medium and reduce standard compressive strength of cement up to 28 %. Calcium orthophosphates hydrates of hydroxyapatite group are stable in alcaline medium, while in dry state they reduce the standard compressive strength of cement until 10 %, but their suspensions prolong setting times of Portland cement as soluble orthophosphates – 2 - 3 times. Alkalis in cement increase pH of paste, but do not change the process of formation of calcium orthophosphates hydrates of hydroxyapatite group: it takes place through an intermediate phase - CaHPO4·2H2O, whose transformation into apatite lasts for 2 - 3 months.

  12. Physical characteristics, antimicrobial and odontogenesis potentials of calcium silicate cement containing hinokitiol

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Ming-Hsien [Institute of Oral Science, Chung Shan Medical University, Taichung City, Taiwan (China); Shen, Yu-Fang; Hsu, Tuan-Ti [3D Printing Medical Research Center, China Medical University Hospital, China Medical University, Taichung City, Taiwan (China); Huang, Tsui-Hsien [School of Dentistry, Chung Shan Medical University, Taichung City, Taiwan (China); Department of Stomatology, Chung Shan Medical University Hospital, Taichung City, Taiwan (China); Shie, Ming-You, E-mail: eviltacasi@gmail.com [3D Printing Medical Research Center, China Medical University Hospital, China Medical University, Taichung City, Taiwan (China)

    2016-08-01

    Hinokitiol is a natural material and it has antibacterial and anti-inflammatory effects. The purpose of this study was to evaluate the material characterization, cell viability, antibacterial and anti-inflammatory abilities of the hinokitiol-modified calcium silicate (CS) cement as a root end filling material. The setting times, diametral tensile strength (DTS) values and XRD patterns of CS cements with 0–10 mM hinokitiol were examined. Then, the antibacterial effect and the expression levels of cyclooxygenase 2 (COX-2) and interleukin-1 (IL-1) of the hinokitiol-modified CS cements were evaluated. Furthermore, the cytocompatibility, the expression levels of the markers of odontoblastic differentiation, mineralized nodule formation and calcium deposition of human dental pulp cells (hDPCs) cultured on hinokitiol-modified CS cements were determined. The hinokitiol-modified CS cements had better antibacterial and anti-inflammatory abilities and cytocompatibility than non-modified CS cements. Otherwise, the hinokitiol-modified CS cements had suitable setting times and better odontoblastic potential of hDPCs. Previous report pointed out that the root-end filling materials may induce inflammatory cytokines reaction. In our study, hinokitiol-modified CS cements not only inhibited the expression level of inflammatory cytokines, but also had better cytocompatibility, antimicrobial properties and active ability of odontoblastic differentiation of hDPCs. Therefore, the hinokitiol-modified CS cement may be a potential root end filling material for clinic. - Highlights: • The hinokitiol-modified CS up-regulation of odontogenic of hDPCs. • Promoted proliferation of hDPCs on hinokitiol-modified CS. • The hinokitiol-modified CS cements not only inhibited the expression level of inflammatory cytokines, but also had better cytocompatibility. • The hinokitiol-modified CS up-regulation of odontogenic of hPDLs.

  13. Impact of fuel selection on the environmental performance of post-combustion calcium looping applied to a cement plant

    NARCIS (Netherlands)

    Schakel, Wouter|info:eu-repo/dai/nl/369280784; Hung, Christine Roxanne; Tokheim, Lars Andre; Strømman, Anders Hammer; Worrell, Ernst|info:eu-repo/dai/nl/106856715; Ramírez, Andrea|info:eu-repo/dai/nl/284852414

    2018-01-01

    Calcium looping CO2 capture is a promising technology to reduce CO2 emissions from cement production. Coal has been seen as a logical choice of fuel to drive the calcium looping process as coal is already the primary fuel used to produce cement. This study assesses the impact of using different

  14. Hydration of Blended Portland Cements Containing Calcium-Aluminosilicate Glass Powder and Limestone

    DEFF Research Database (Denmark)

    Moesgaard, M; Poulsen, Søren Lundsted; Herfort, D

    2012-01-01

    M. MOESGAARD, S.L. POULSEN, D. HERFORT, M. STEENBERG, L.F. KIRKEGAARD, J. SKIBSTED, Y. YUE, Hydration of Blended Portland Cements Containing Calcium-Aluminosilicate Glass Powder and Limestone, Journal of the American Ceramic Society 95, 403 – 409 (2012).......M. MOESGAARD, S.L. POULSEN, D. HERFORT, M. STEENBERG, L.F. KIRKEGAARD, J. SKIBSTED, Y. YUE, Hydration of Blended Portland Cements Containing Calcium-Aluminosilicate Glass Powder and Limestone, Journal of the American Ceramic Society 95, 403 – 409 (2012)....

  15. In-situ early-age hydration study of sulfobelite cements by synchrotron powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Álvarez-Pinazo, G.; Cuesta, A.; García-Maté, M.; Santacruz, I.; Losilla, E.R. [Departamento de Química Inorgánica, Universidad de Málaga, Campus Teatinos S/N., 29071 Málaga (Spain); Sanfélix, S.G. [Unidad Técnica de Investigación de Materiales, AIDICO, Avda. Benjamín Franklin, 17 Paterna, Valencia (Spain); Fauth, F. [CELLS-Alba synchrotron, Carretera BP 1413, Km. 3.3, E-08290 Cerdanyola, Barcelona (Spain); Aranda, M.A.G. [Departamento de Química Inorgánica, Universidad de Málaga, Campus Teatinos S/N., 29071 Málaga (Spain); CELLS-Alba synchrotron, Carretera BP 1413, Km. 3.3, E-08290 Cerdanyola, Barcelona (Spain); De la Torre, A.G., E-mail: mgd@uma.es [Departamento de Química Inorgánica, Universidad de Málaga, Campus Teatinos S/N., 29071 Málaga (Spain)

    2014-02-15

    Eco-friendly belite calcium sulfoaluminate (BCSA) cement hydration behavior is not yet well understood. Here, we report an in-situ synchrotron X-ray powder diffraction study for the first hours of hydration of BCSA cements. Rietveld quantitative phase analysis has been used to establish the degree of reaction (α). The hydration of a mixture of ye'elimite and gypsum revealed that ettringite formation (α ∼ 70% at 50 h) is limited by ye'elimite dissolution. Two laboratory-prepared BCSA cements were also studied: non-active-BCSA and active-BCSA cements, with β- and α′{sub H}-belite as main phases, respectively. Ye'elimite, in the non-active-BCSA system, dissolves at higher pace (α ∼ 25% at 1 h) than in the active-BCSA one (α ∼ 10% at 1 h), with differences in the crystallization of ettringite (α ∼ 30% and α ∼ 5%, respectively). This behavior has strongly affected subsequent belite and ferrite reactivities, yielding stratlingite and other layered phases in non-active-BCSA. The dissolution and crystallization processes are reported and discussed in detail. -- Highlights: •Belite calcium sulfoaluminate cements early hydration mechanism has been determined. •Belite hydration strongly depends on availability of aluminum hydroxide. •Orthorhombic ye’elimite dissolved at a higher pace than cubic one. •Ye’elimite larger reaction degree yields stratlingite formation by belite reaction. •Rietveld method quantified gypsum, anhydrite and bassanite dissolution rates.

  16. Physicochemical properties and biocompatibility of chitosan oligosaccharide/gelatin/calcium phosphate hybrid cements

    Energy Technology Data Exchange (ETDEWEB)

    Chiang, Ting-Yi [Department of Dental Laboratory Technology, Central Taiwan University of Science and Technology, Taichung 406, Taiwan (China); Ho, Chia-Che [Institute of Oral Biology and Biomaterials Science, Chung-Shan Medical University, Taichung 402, Taiwan (China); Chen, David Chan-Hen [Institute of Veterinary Microbiology, National Chung-Hsing University, Taichung 402, Taiwan (China); Lai, Meng-Heng [Institute of Oral Biology and Biomaterials Science, Chung-Shan Medical University, Taichung 402, Taiwan (China); Ding, Shinn-Jyh, E-mail: sjding@csmu.edu.tw [Institute of Oral Biology and Biomaterials Science, Chung-Shan Medical University, Taichung 402, Taiwan (China); Department of Dentistry, Chung-Shan Medical University Hospital, Taichung 402, Taiwan (China)

    2010-04-15

    A bone substitute material was developed consisting of a chitosan oligosaccharide (COS) solution in a liquid phase and gelatin (GLT) containing calcium phosphate powder in a solid phase. The physicochemical and biocompatible properties of the hybrid cements were evaluated. The addition of COS to cement did not affect the setting time or diametral tensile strength of the hybrid cements, whereas GLT significantly prolonged the setting time and decreased the strength slightly. The setting reaction was inhibited by the addition of GLT to the initial mixture, but not by COS. However, the presence of GLT appreciably improved the anti-washout properties of the hybrid cement compared with COS. COS may promote the cement's biocompatibility as an approximate twofold increase in cell proliferation for 10% COS-containing cements was observed on day 3 as compared with the controls. The combination of GLT and COS was chosen due to the benefits achieved from several synergistic effects and for their clinical applications. Cement with 5% GLT and 10% COS may be a better choice among cements in terms of anti-washout properties and biological activity.

  17. Evaluation of elevated temperature properties of asphalt cement modified with aluminum oxide and calcium carbonate nanoparticles

    Science.gov (United States)

    Albrka Ali, Shaban Ismael; Ismail, Amiruddin; AlMansob, Ramez A.; Alhmali, Dhawo Ibrahim

    2017-09-01

    Higher temperature properties of the asphalt cement have been characterized before and after modification using dynamic shear rheometer (DSR) and viscosity testing. In this study, calcium carbonate nanoparticles (CaCO3) and aluminum oxide nanoparticles (Al2O3) have been added to the base asphalt cement with concentrations of 3, 5 and 7%.wt by the weight of the asphalt cement. The increase of CaCO3 and Al2O3 content has significant effect on the properties of asphalt cement. The viscosity of the modified asphalt cement increased up to 90 and 108% respectively compared to the base asphalt cement. In addition, the results showed that both modifiers have great storage stability and compatibility at elevated temperature. The evaluation of the rheological properties of asphalt cements revealed that the stiffness of the modified samples improved with additional increase of the modifier concentration of up to 5%, which indicates better resistance to rutting parameter. The enhancement was up to 388.89% for Al2O3 and 74.07% for CaCO3. As a result, the usage of CaCO3 and Al2O3 nanoparticles can be considered as appropriate alternative materials to modify asphalt cement.

  18. Particle size of a new endodontic cement compared to Root MTA and calcium hydroxide

    OpenAIRE

    Soheilipour, Elham; Kheirieh, Sanam; Madani, Majid; Akbarzadeh Baghban, Alireza; Asgary, Saeed

    2009-01-01

    INTRODUCTION: Particle size and distribution can influence the properties of materials. This study analyzed and compared the particle size of Root MTA, calcium hydroxide (CH), and a new endodontic cement called calcium enriched material (CEM). MATERIALS AND METHODS: The particle size of each material was analyzed three times using 0.05 mg of test material with a particle size analyzer. The particle size distribution ranges, the cumulative percentage and the mean of particle sizes were calcula...

  19. Long-term biological performance of injectable and degradable calcium phosphate cement

    NARCIS (Netherlands)

    Grosfeld, E.C.; Hoekstra, J.W.M.; Herber, R.P.; Ulrich, D.J.O.; Jansen, J.A.; Beucken, J.J.J.P van den

    2016-01-01

    Enhancing degradation of poorly degrading injectable calcium phosphate (CaP) cements (CPCs) can be achieved by adding poly(lactic-co-glycolic acid) (PLGA) microparticles, generating porosity after polymer degradation. CPC-PLGA has proven to be biodegradable, although its long-term biological

  20. Analysis of the color alteration and radiopacity promoted by bismuth oxide in calcium silicate cement.

    Science.gov (United States)

    Marciano, Marina Angélica; Estrela, Carlos; Mondelli, Rafael Francisco Lia; Ordinola-Zapata, Ronald; Duarte, Marco Antonio Hungaro

    2013-01-01

    The aim of the study was to determine if the increase in radiopacity provided by bismuth oxide is related to the color alteration of calcium silicate-based cement. Calcium silicate cement (CSC) was mixed with 0%, 15%, 20%, 30% and 50% of bismuth oxide (BO), determined by weight. Mineral trioxide aggregate (MTA) was the control group. The radiopacity test was performed according to ISO 6876/2001. The color was evaluated using the CIE system. The assessments were performed after 24 hours, 7 and 30 days of setting time, using a spectrophotometer to obtain the ΔE, Δa, Δb and ΔL values. The statistical analyses were performed using the Kruskal-Wallis/Dunn and ANOVA/Tukey tests (pbismuth oxide was added showed radiopacity corresponding to the ISO recommendations (>3 mm equivalent of Al). The MTA group was statistically similar to the CSC/30% BO group (p>0.05). In regard to color, the increase of bismuth oxide resulted in a decrease in the ΔE value of the calcium silicate cement. The CSC group presented statistically higher ΔE values than the CSC/50% BO group (pbismuth oxide has no relation to the color alteration of calcium silicate-based cements.

  1. Evaluation of the biocompatibility of calcium phosphate cement/PLGA microparticle composites.

    NARCIS (Netherlands)

    Link, D.P.; Dolder, J. van den; Beucken, J.J.J.P van den; Cuijpers, V.M.J.I.; Wolke, J.G.C.; Mikos, A.G.; Jansen, J.A.

    2008-01-01

    In this study, the biocompatibility of a calcium phosphate (CaP) cement incorporating poly (D,L-lactic-co-glycolic acid) (PLGA) microparticles was evaluated in a subcutaneous implantation model in rats. Short-term biocompatibility was assessed using pure CaP discs and CaP discs incorporating PLGA

  2. Incorporation of bioactive glass in calcium phosphate cement: Material characterization and in vitro degradation

    NARCIS (Netherlands)

    Renno, A.C.; Nejadnik, M.R.; Watering, F.C.J. van de; Crovace, M.C.; Zanotto, E.D.; Hoefnagels, J.P.; Wolke, J.G.C.; Jansen, Jan; Beucken, J.J.J.P van den

    2013-01-01

    Calcium phosphate cements (CPCs) have been widely used as an alternative to biological grafts due to their excellent osteoconductive properties. Although degradation has been improved by using poly(D,L-lactic-co-glycolic) acid (PLGA) microspheres as porogens, the biological performance of CPC/PLGA

  3. In vitro degradation rate of apatitic calcium phosphate cement with incorporated PLGA microspheres

    NARCIS (Netherlands)

    Felix Lanao, R.P.; Leeuwenburgh, S.C.G.; Wolke, J.G.C.; Jansen, J.A.

    2011-01-01

    Calcium phosphate cements (CPCs) are frequently used as bone substitute material. Despite their superior clinical handling and excellent biocompatibility, they exhibit poor degradability, which limits bone ingrowth into the implant. Microspheres were prepared from poly(d,l-lactic-co-glycolic acid)

  4. Maxillary sinus floor augmentation with injectable calcium phosphate cements: a pre-clinical study in sheep

    NARCIS (Netherlands)

    Hoekstra, J.W.M.; Klijn, R.J.; Meijer, G.J.; Beucken, J.J.J.P van den; Jansen, J.B.M.J.

    2013-01-01

    OBJECTIVES: The aim of this pre-clinical study was to evaluate the biological performance of two injectable calcium phosphate cement (CPC) composite materials containing poly(D,L-lactic-co-glycolic)acid (PLGA) microspheres with different properties in a maxillary sinus floor elevation model in

  5. Mechanical evaluation of implanted calcium phosphate cement incorporated with PLGA microparticles.

    NARCIS (Netherlands)

    Link, D.P.; Dolder, J. van den; Jurgens, W.J.; Wolke, J.G.C.; Jansen, J.A.

    2006-01-01

    In this study, the mechanical properties of an implanted calcium phosphate (CaP) cement incorporated with 20wt% poly (dl-lactic-co-glycolic acid) (PLGA) microparticles were investigated in a rat cranial defect. After 2, 4 and 8 weeks of implantation, implants were evaluated mechanically (push-out

  6. Biocompatibility and degradation of poly(DL-lactic-co-glycolic acid)/calcium phosphate cement composites

    NARCIS (Netherlands)

    Ruhe, P.Q.; Hedberg, E.L.; Padron, N.T.; Spauwen, P.H.M.; Jansen, J.A.; Mikos, A.G.

    2005-01-01

    Injectable calcium phosphate (Ca-P) cement materials exhibit favorable osteocompatible behavior but are resorbed slowly because of a lack of a bone ingrowth-enabling macroporosity. In this study, poly(DL-lactic-co-glycolic acid) (PLGA) microparticles (average size 66 +/- 25 microm) were incorporated

  7. Influence of polymeric additives on the cohesion and mechanical properties of calcium phosphate cements.

    NARCIS (Netherlands)

    An, J.; Wolke, J.G.C.; Jansen, J.A.; Leeuwenburgh, S.C.G.

    2016-01-01

    To expand the clinical applicability of calcium phosphate cements (CPCs) to load-bearing anatomical sites, the mechanical and setting properties of CPCs need to be improved. Specifically, organic additives need to be developed that can overcome the disintegration and brittleness of CPCs. Hence, we

  8. Porosity distribution in root canals filled with gutta percha and calcium silicate cement

    NARCIS (Netherlands)

    Moinzadeh, A.T.; Zerbst, W.; Boutsioukis, C.; Shemesh, H.; Zaslansky, P.

    2015-01-01

    Objective Gutta percha is commonly used in conjunction with a sealer to produce a fluid-tight seal within the root canal fillings. One of the most commonly used filling methods is lateral compaction of gutta percha coupled with a sealer such as calcium silicate cement. However, this technique may

  9. Incorporation of fast dissolving glucose porogens into an injectable calcium phosphate cement for bone tissue engineering.

    NARCIS (Netherlands)

    Smith, B.T.; Santoro, M.; Grosfeld, E.C.; Shah, S.R.; Beucken, J.J.J.P van den; Jansen, J.A.; Mikos, A.G.

    2017-01-01

    Calcium phosphate cements (CPCs) have been extensively investigated as scaffolds in bone tissue engineering in light of their chemical composition closely resembling the mineral component of bone extracellular matrix. Yet, the degradation kinetics of many CPCs is slow compared to de novo bone

  10. Calcium orthophosphate-based bone cements (CPCs): Applications, antibiotic release and alternatives to antibiotics.

    Science.gov (United States)

    Van Staden, Anton D; Dicks, Leon M T

    2012-06-26

    Calcium orthophosphate bone cements (CPCs) are widely used in orthopedic surgery. Implants are highly susceptible to infection and often lead to the formation of microbial biofilms. Antibiotics are often incorporated into bone cement to prevent infection. The increase in the number of microorganisms acquiring or developing resistance to antibiotics, such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), is a major concern. Bacteriocins (antimicrobial peptides) offer an alternative to antibiotics. Their mode of activity involves permanent destabilization of the plasma membrane of target cells. A number of broad-spectrum bacteriocins produced by lactic acid bacteria and Bacillus spp. have recently been reported. In this REVIEW the major characteristics of calcium phosphate bone cements, prosthetic joint-associated infections, and treatment of these infections is discussed. The role of antimicrobial agents in CPCs is discussed and the possibility of incorporating bacteriocins in prosthetic devices is investigated.

  11. On the development of an apatitic calcium phosphate bone cement

    Indian Academy of Sciences (India)

    Unknown

    of the putty were measured using a Vicat type apparatus and the compressive strength was determined with a. Universal Testing Machine. The nature of the precipitated cement was analyzed through X-ray diffraction. (XRD), fourier transform infrared spectrometry (FTIR) and energy dispersive electron microprobe (EDAX).

  12. On the development of an apatitic calcium phosphate bone cement

    Indian Academy of Sciences (India)

    The setting times of the putty were measured using a Vicat type apparatus and the compressive strength was determined with a Universal Testing Machine. The nature of the precipitated cement was analyzed through X-ray diffraction (XRD), fourier transform infrared spectrometry (FTIR) and energy dispersive electron ...

  13. SEALING ABILITY OF MINERAL TRIOXIDE AGGREGATE, CALCIUM PHOSPHATE CEMENT, AND GLASS IONOMER CEMENT IN THE REPAIR OF FURCATION PERFORATIONS

    Directory of Open Access Journals (Sweden)

    Prabath Singh

    2013-01-01

    Full Text Available Objectives: The purpose of this study was to evaluate the in vitro sealing ability of three repair materials. Mineral trioxide aggregate (MTA; Group A, calcium phosphate cement (CPC; Group B, and light cured glass ionomer cement (GIC; Group C when used to repair the perforation created in the pulpal floor of fifty extracted human permanent molars. Materials and methods: Preparation of access openings and furcation perforations were done, and the teeth divided into five experimental groups (A, B, C including two controls (D, E with ten samples in each group randomly. Following the repair procedure, the pulp chambers and access openings were filled with composite resin and immersed in 2% methylene blue solution for 48 hours. The teeth were sectioned longitudinally and the linear dye penetration measured under a stereo­microscope. Results: The comparison of the linear length of micro-leakage (mm among the experimental groups revealed no significant difference (p = 0.332. On calculating the percentage of depth of leakage to the total length of the perforation, it was observed that the mean leakage was 35.5% in Group A, 53.6% in Group B and the highest, 87.5% in Group C. The mean of leakage percentage was statistically significant by Kruskal-Wallis test (p = 0.003. The results indicated that the dye penetration used as furcation perforation repair material was least with mineral trioxide aggregate. Comparing the depth of penetration of dye, 50% of the Group A samples showed less than 25% of depth penetration. While 40% of Group B cases had more than 50% dye penetration. In our study, all Group C teeth had ≥ 50% dye penetration. Conclusions: The present study indicated that GIC had the greatest dye penetration followed by CPC and MTA. Mineral trioxide aggregate and calcium phosphate cement had comparatively better sealing ability than glass ionomer cement.

  14. Alite-ye'elimite cement: Synthesis and mineralogical analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Suhua [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Materials Science and Engineering, Nanjing University of Technology, Nanjing 210009 (China); Snellings, Ruben [Laboratory of Construction Materials, Institute of Materials, Ecole Polytechnique Fédéral de Lausanne, Station 12, CH-1015 Ecublens (Switzerland); Li, Xuerun [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Materials Science and Engineering, Nanjing University of Technology, Nanjing 210009 (China); Shen, Xiaodong, E-mail: xdshen@njut.edu.cn [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Materials Science and Engineering, Nanjing University of Technology, Nanjing 210009 (China); Scrivener, Karen L. [Laboratory of Construction Materials, Institute of Materials, Ecole Polytechnique Fédéral de Lausanne, Station 12, CH-1015 Ecublens (Switzerland)

    2013-03-15

    Alite-ye'elimite cement is an alternative cement that combines desirable characteristics of calcium sulfoaluminate cements and Portland cement in that it shows improved strength development at early age while retaining high portlandite contents. The key problem in the clinkering process is to produce the alite-ye'elimite phase assemblage so that both phases can co-exist. In this study, a new synthesis method is proposed to achieve the coexistence of alite and ye'elimite consisting of a secondary heat treatment step at 1250 °C after regular Portland clinker firing at 1450 °C. Quantitative X-ray powder diffraction and electron microscopy were used to analyze the phase composition of clinker before and after the secondary heat treatment. The results show that ye'elimite develops during secondary heat treatment of calcium sulphate enriched clinker by reaction of C{sub 3}A and sulphate phases. Additional ferrite is formed as result of rejection of Fe originally in solid solution with C{sub 3}A during ye'elimite formation.

  15. An experimental approach to the study of the rheology behaviour of synthetic bone calcium phosphate cements

    Energy Technology Data Exchange (ETDEWEB)

    Friberg, J.; Fernandez, E.; Sarda, S.; Nilsson, M.; Ginebra, M.P.; Planell, J.A. [Universidad Politecnica de Catalunya, Barcelona (Spain). Dept. of Materials Science and Metallurgical Engineering; Martinez, S. [Barcelona Univ. (Spain). Mineralogia i Recursos Minerals

    2001-07-01

    Calcium phosphate cements were developed to fit surgical needs in biomedical fields such as odontology or traumatology. Nowadays, a broad field of new applications have been found for this kind of materials. Drug delivery systems, tissue-engineering scaffolds and osteoporotic bone filling applications are some of the new fields that are being benefited with these materials. Looking at both, commercial and new experimental calcium phosphate cements it is found that {alpha}-tricalcium phosphate is the main reactive powder responsible for the setting and the hardening of the cement. Thus, it is important to know how {alpha}-tricalcium phosphate affects injectability of these cements. The aim of this study was to investigate the rheological behaviour of {alpha}-tricalcium phosphate slurries in order to know how the cement injectability should be modified. Factors such as liquid to powder ratio, particle size of the main reactive powder and the addition of dispersants have been considered. The results showed that viscosity decreased when particle size of reactant was increased and when liquid to powder ratio was increased. It was also found that a minimum of viscosity exists at an optimum value of the weight percentage of dispersant. (orig.)

  16. In vitro and in vivo study of commercial calcium phosphate cement HydroSet™.

    Science.gov (United States)

    Kent, Niall W; Blunn, Gordon; Karpukhina, Natalia; Davis, Graham; de Godoy, Roberta Ferro; Wilson, Rory M; Coathup, Melanie; Onwordi, Lyris; Quak, Wen Yu; Hill, Robert

    2018-01-01

    The commercial calcium phosphate cement, HydroSet™, was investigated in vitro, studying phase formation, compressive strength and setting time, followed by an ovine in vivo study to measure osseointegration, bone apposition and bone-to-graft contact. The X-ray diffraction and 31 P Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) results showed the initial formation of octacalcium phosphate and hydroxyapatite at one hour. Over 7 days the octacalcium phosphate transformed to apatite, which was the only crystalline phase of the cement at 28 days. This apatite phase is thought to be a calcium deficient apatite. In the scanning electron microscopy, histological images of 12-week ovine in vivo results showed a high degree of osseointegration, 92.5%. Compressive strength comparisons between in vitro and in vivo measurements showed a dramatic difference between the in vitro measurements (highest 25.4 MPa) and in vivo (95 MPa), attributed to bone ingrowth into the cement in vivo. To the best of our knowledge this is the first time phase evolution of HydroSet™ and the properties studied in vitro complement the in vivo evaluation of the cement in a publication. The significance of the new finding of initial formation of octacalcium phosphate in this cement is discussed. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 21-30, 2018. © 2016 Wiley Periodicals, Inc.

  17. Phase composition, mechanical performance and in vitro biocompatibility of hydraulic setting calcium magnesium phosphate cement.

    Science.gov (United States)

    Klammert, Uwe; Reuther, Tobias; Blank, Melanie; Reske, Isabelle; Barralet, Jake E; Grover, Liam M; Kübler, Alexander C; Gbureck, Uwe

    2010-04-01

    Brushite (CaHPO(4) x 2H(2)O)-forming calcium phosphate cements are of great interest as bone replacement materials because they are resorbable in physiological conditions. However, their short setting times and low mechanical strengths limit broad clinical application. In this study, we showed that a significant improvement of these properties of brushite cement could be achieved by the use of magnesium-substituted beta-tricalcium phosphate with the general formula Mg(x)Ca((3-x))((PO(4))(2) with 0 forming newberyite (MgHPO(4) x 3H(2)O) as a second setting product. The biocompatibility of the material was investigated in vitro using the osteoblast-like cell line MC3T3-E1. A considerable increase of cell proliferation and expression of alkaline phosphatase, indicating an osteoblastic differentiation, could be noticed. Scanning electron microscopy analysis revealed an obvious cell growth on the surface of the scaffolds. Analysis of the culture medium showed minor alterations of pH value within the physiological range. The concentrations of free calcium, magnesium and phosphate ions were altered markedly due to the chemical solubility of the scaffolds. We conclude that the calcium magnesium phosphate (newberyite) cements have a promising potential for their use as bone replacement material since they provide a suitable biocompatibility, an extended workability and improved mechanical performance compared with brushite cements. Copyright 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  18. Cytotoxicity and genotoxicity of calcium silicate-based cements on an osteoblast lineage

    Directory of Open Access Journals (Sweden)

    Ana Lívia GOMES-CORNÉLIO

    2016-01-01

    Full Text Available Abstract Several calcium silicate-based biomaterials have been developed in recent years, in addition to Mineral Trioxide Aggregate (MTA. The aim of this study was to evaluate the cytotoxicity, genotoxicity and apoptosis/necrosis in human osteoblast cells (SAOS-2 of pure calcium silicate-based cements (CSC and modified formulations: modified calcium silicate-based cements (CSCM and three resin-based calcium silicate cements (CSCR1 (CSCR 2 (CSCR3. The following tests were performed after 24 hours of cement extract exposure: methyl-thiazolyl tetrazolium (MTT, apoptosis/necrosis assay and comet assay. The negative control (CT- was performed with untreated cells, and the positive control (CT+ used hydrogen peroxide. The data for MTT and apoptosis were submitted to analysis of variance and Bonferroni’s posttest (p < 0.05, and the data for the comet assay analysis, to the Kruskal-Wallis and Dunn tests (p < 0.05. The MTT test showed no significant difference among the materials in 2 mg/mL and 10 mg/mL concentrations. CSCR3 showed lower cell viability at 10 mg/mL. Only CSC showed lower cell viability at 50 mg/mL. CSCR1, CSCR2 and CSCR3 showed a higher percentage of initial apoptosis than the control in the apoptosis test, after 24 hours exposure. The same cements showed no genotoxicity in the concentration of 2 mg/mL, with the comet assay. CSC and CSCR2 were also not genotoxic at 10 mg/mL. All experimental materials showed viability with MTT. CSC and CSCR2 presented a better response to apoptosis and genotoxicity evaluation in the 10 mg/mL concentration, and demonstrated a considerable potential for use as reparative materials.

  19. Biomechanical evaluation of vertebroplasty and kyphoplasty with polymethyl methacrylate or calcium phosphate cement under cyclic loading.

    Science.gov (United States)

    Wilke, Hans-Joachim; Mehnert, Ulrich; Claes, Lutz E; Bierschneider, Michael M; Jaksche, Hans; Boszczyk, Bronek M

    2006-12-01

    We developed a new method to simulating in vivo dynamic loading as closely as possible, which allows comparison of kyphoplasty and vertebroplasty, as well as augmentation materials. Special interest was given to calcium phosphate cement, which might fail due to its brittleness. Vertebroplasty and kyphoplasty are, with limitations, 2 promising alternative techniques to augment osteoporotic vertebrae with polymethyl methacrylate or calcium phosphate cements. However, little is known about the fatigue characteristics of the treated vertebrae under cyclic loading. Twenty-four intact, osteoporotic bi-segmental human specimens were divided into 4 groups: (1) vertebroplasty with polymethyl methacrylate, (2) kyphoplasty with polymethyl methacrylate, (3) kyphoplasty with calcium phosphate cement, and (4) untreated control group. After augmentation of the middle vertebrae, all specimens underwent 100,000 cycles of eccentric loading during which the specimen revolved around its longitudinal axis. Pre-loading and post-loading radiographs, and subsidence measurements at different sites of the vertebrae were taken. The overall height was additionally determined every 20,000 cycles in the material testing machine. Finally, the specimens were cryosectioned to examine the cements. Loss of height progressed with strong individual differences in all groups, with an increasing number of load cycles up to median values of 2.8 mm for both augmented groups and 4.2 mm for the nonaugmented group. At the center of the upper endplate, subsidence in kyphoplasty was greater than in vertebroplasty, with little differences with respect to the kind of cement. The cryosections did not show any signs of fatigue in the polymethyl methacrylate, but small cracks were in the calcium phosphate. Vertebroplasty and kyphoplasty seem to be equivalent methods in strengthening osteoporotic vertebrae. However, these results cannot be transferred to the treatment of fractures with these methods. A "physiologic

  20. The effect on the pullout strength by the timing of pedicle screw insertion after calcium phosphate cement injection.

    Science.gov (United States)

    Cho, Woojin; Wu, Chunhui; Erkan, Serkan; Kang, Matthew M; Mehbod, Amir A; Transfeldt, Ensor E

    2011-04-01

    Biomechanical Cadaveric Study. To characterize the pullout strength of calcium phosphate cement augmented screws between 0 and 6 minutes after cement injection. Earlier studies with calcium phosphate cement on pedicle screws inserted into a metal mold or sawbone have shown that the augmentation strength can be affected by the time between cement injection and screw insertion. However, these studies only compared soft cement to completely hardened cement with extended waiting times. These extended waiting times are impractical in live spinal surgeries. Twenty-four pedicle screws were inserted and pulled out axially from cadaveric bone to make revision models. The 24 screw holes were randomly divided into 4 groups, with each group having 6 holes. For each group, identical pedicle screws were inserted at 0, 2, 4, and 6 minutes after injection with bioresorbable calcium phosphate cement (CPC). After 24 hours, the augmented screws were pulled out axially and their pullout strengths were compared. The difference between secondary pullout strength and primary pullout strength increased up to 4 minutes after cement injection but decreased after 6 minutes but without statistical difference among the 4 time settings (P>0.3). The augmented screws had similar fixation strength regardless of the time between cement mixture and screw insertion as long as they are inserted within 6 minutes. Augmentation power tends to increase up to 4 minutes after cement injection but decreases after 6 minutes.

  1. Strontium enhances osseointegration of calcium phosphate cement: a histomorphometric pilot study in ovariectomized rats

    Science.gov (United States)

    2013-01-01

    Background Calcium phosphate cements are used frequently in orthopedic and dental surgeries. Strontium-containing drugs serve as systemic osteoblast-activating medication in various clinical settings promoting mechanical stability of the osteoporotic bone. Methods Strontium-containing calcium phosphate cement (SPC) and calcium phosphate cement (CPC) were compared regarding their local and systemic effects on bone tissue in a standard animal model for osteoporotic bone. A bone defect was created in the distal femoral metaphysis of 60 ovariectomized Sprague-Dawley rats. CPC and SPC were used to fill the defects in 30 rats in each group. Local effects were assessed by histomorphometry at the implant site. Systemic effects were assessed by bone mineral density (BMD) measurements at the contralateral femur and the spine. Results Faster osseointegration and more new bone formation were found for SPC as compared to CPC implant sites. SPC implants exhibited more cracks than CPC implants, allowing more bone formation within the implant. Contralateral femur BMD and spine BMD did not differ significantly between the groups. Conclusions The addition of strontium to calcium phosphate stimulates bone formation in and around the implant. Systemic release of strontium from the SPC implants did not lead to sufficiently high serum strontium levels to induce significant systemic effects on bone mass in this rat model. PMID:23758869

  2. Substitution of strontium for calcium in glass ionomer cements (Part ...

    African Journals Online (AJOL)

    Design: An exploratory, laboratory-based study. Setting: Dental biomaterials research laboratory, Dental Physical Sciences Unit, Barts and the London School of Medicine and Dentistry, Queen Mary, University of London. Subjects: A series of five glasses in which strontium substitutes for calcium and based on the general ...

  3. properties of cement paste and concrete containing calcium carbide

    African Journals Online (AJOL)

    user

    2017-01-01

    Jan 1, 2017 ... 1 DEPARTMENT OF CIVIL ENGINEERING, BAYERO UNIVERSITY, PMB 3011 KANO, KANO STATE, NIGERIA. 2 NIGERIAN ... The results of the investigations showed that CCW was predominantly of calcium oxide (95.69 %) and a combined SiO2, ..... concrete”, International Journal of Innovative Science,.

  4. Clogging and Cementation Caused by Calcium or Iron Biogrouts

    Science.gov (United States)

    Ivanov, V.; Chu, J.; Naeimi, M.

    2012-12-01

    Chemical grouts are often used to reduce the hydraulic conductivity of soil for seepage control purposes. However, chemical grouts can be expensive and environmentally unfriendly. Therefore, two new biogrouts were tested for their bioclogging and biocementation properties. The first was calcium-based biogrout, which contained urease-producing bacteria, calcium chloride and urea for the crystallization of calcite due to enzymatic hydrolysis of urea. The second was iron-based biogrout, which consisted of urease-producing bacteria, ferric chelate, and urea for the precipitation of ferric hydroxide and carbonate due to enzymatic hydrolysis of urea. The permeability of sand (P, 10^-5 m/s), treated with calcium-based biogrout, linearly decreased as a function of the content of precipitated calcium (C, % w/w) according to the following equation: P = 5.1 - 4.0 C. Meanwhile, the permeability of sand treated with iron-based biogrout dropped to 2.7x10^-6 m/s at content of precipitated iron (F, % w/w) about 0.35 % w/w , by the equation: P = 5.1 - 14.6 F , and then slowly decreased to 1.4x10^-7 m/s at content of precipitated iron 1.8% w/w by the following equation: P = 0.36 - 0.23F. Both biogrouts have approximately same efficiency in the reduction of permeability of sand to low values. However, the mechanisms of bioclogging are probably different because the reduction of permeability by calcium-based biogrout was described by linear function of precipitated calcium but the reduction of permeability by iron-based biogrout showed two steps of the clogging. Different functions and mechanisms were related probably to the different type of precipitates. The images of biogrouted sand samples show that calcium-based biogrout produced white amorphous or crystallised calcium carbonate, while iron-based biogrout produced gel-like brown precipitate without visible crystals. The unconfined compressive strengths of the sand treated with different biogrouts (Y, kPa) increased by power

  5. Apatite formation on bioactive calcium-silicate cements for dentistry affects surface topography and human marrow stromal cells proliferation.

    Science.gov (United States)

    Gandolfi, Maria Giovanna; Ciapetti, Gabriela; Taddei, Paola; Perut, Francesca; Tinti, Anna; Cardoso, Marcio Vivan; Van Meerbeek, Bart; Prati, Carlo

    2010-10-01

    The effect of ageing in phosphate-containing solution of bioactive calcium-silicate cements on the chemistry, morphology and topography of the surface, as well as on in vitro human marrow stromal cells viability and proliferation was investigated. A calcium-silicate cement (wTC) mainly based on dicalcium-silicate and tricalcium-silicate was prepared. Alpha-TCP was added to wTC to obtain wTC-TCP. Bismuth oxide was inserted in wTC to prepare a radiopaque cement (wTC-Bi). A commercial calcium-silicate cement (ProRoot MTA) was tested as control. Cement disks were aged in DPBS for 5 h ('fresh samples'), 14 and 28 days, and analyzed by ESEM/EDX, SEM/EDX, ATR-FTIR, micro-Raman techniques and scanning white-light interferometry. Proliferation, LDH release, ALP activity and collagen production of human marrow stromal cells (MSC) seeded for 1-28 days on the cements were evaluated. Fresh samples exposed a surface mainly composed of calcium-silicate hydrates CSH (from the hydration of belite and alite), calcium hydroxide, calcium carbonate, and ettringite. Apatite nano-spherulites rapidly precipitated on cement surfaces within 5 h. On wTC-TCP the Ca-P deposits appeared thicker than on the other cements. Aged cements showed an irregular porous calcium-phosphate (Ca-P) coating, formed by aggregated apatite spherulites with interspersed calcite crystals. All the experimental cements exerted no acute toxicity in the cell assay system and allowed cell growth. Using biochemical results, the scores were: fresh cements>aged cements for cell proliferation and ALP activity (except for wTC-Bi), whereas fresh cementsbismuth on cell proliferation was reduced by the progressive increase of the biocoating thickness on aged cement. In conclusion, the experimental cements have adequate biological properties to be used as root-end/root repair filling materials or pulp capping materials. The alfa-TCP doped cement represents a new potential bioactive material for expanded applications in

  6. A comparative study on sealing ability of mineral trioxide aggregate, calcium enriched cement and bone cement in furcal perforations.

    Science.gov (United States)

    Nazari Moghadam, K; Aghili, H; Rashed Mohassel, A; Zahedpasha, S; Moghadamnia, A A

    2014-06-01

    The aim of this study was to compare the bacterial leakage of mineral trioxide aggregate (MTA), calcium enriched cement (CEM), and bone cement (BC) as repair materials in furcal perforations. The pulp chambers of 57 human mandibular molar teeth were accessed and the root canal orifices were located. The roots were horizontally sectioned in the middle third. Composite resin was used to fill the root canal orifices and the apical end of the roots. The 1 mm furcation perforations were performed in the center of the pulp chamber floor, using diamond fissure burs. Fifty one teeth were divided into 3 groups. Six teeth were used as controls. Perforation defects were repaired with either MTA, CEM, or BC. A bacterial leakage model utilizing phenol red with 3% lactose broth was used for evaluation. The upper pulp chambers were subsequently filled with 5μL bacterial suspension containing Enterococcus faecalis. Then the top of the assembly was covered with aluminum foil to avoid unintentional contamination. The entire apparatus was incubated at 37°C, and bacterial leakage was evaluated daily by checking the turbidity in the culture medium of the lower part of the chamber. The bacterial inoculation was renewed every day, for 30 days. Leakage was noted when color conversion of the culture media was observed and was statistically analyzed using the Chi-square test with significance set at P0.05). According to the present study, in teeth with furcation perforations, the coronal seal produced by MTA preparations was equally to that produced by CEM cement and Bone cement.

  7. Hydration of Blended Portland Cements Containing Calcium-Aluminosilicate Glass Powder and Limestone

    DEFF Research Database (Denmark)

    Moesgaard, Mette; Poulsen, S.L.; Herfort, D.

    2012-01-01

    This work investigates the hydration of blended Portland cement containing 30 wt.% Na2O-CaO-Al2O3-SiO2 (NCAS) glass particles either as the only supplementary cementitious material (SCM) or in combination with limestone, using 29Si MAS NMR, powder XRD, and thermal analyses. The NCAS glass...... represents a potential alternative to traditional SCMs, used for reduction of the CO2 emission associated with cement production. It is found that the NCAS glass takes part in the hydration reactions after about two weeks of hydration and a degree of reaction of approx. 50 % is observed after 90 days...... of hydration. The hydrated glass contributes to the formation of the calcium-silicate-hydrate (C-S-H) phase, consuming a part of the Portlandite (Ca(OH)2) formed during hydration of the Portland cement. Furthermore, the presence of the glass and limestone particles, alone or in combination, results...

  8. Monitoring of hardening and hygroscopic induced strains in a calcium phosphate bone cement using FBG sensor.

    Science.gov (United States)

    Bimis, A; Karalekas, D; Bouropoulos, N; Mouzakis, D; Zaoutsos, S

    2016-07-01

    This study initially deals with the investigation of the induced strains during hardening stage of a self-setting calcium phosphate bone cement using fiber-Bragg grating (FBG) optical sensors. A complementary Scanning Electron Microscopy (SEM) investigation was also conducted at different time intervals of the hardening period and its findings were related to the FBG recordings. From the obtained results, it is demonstrated that the FBG response is affected by the microstructural changes taking place when the bone cement is immersed into the hardening liquid media. Subsequently, the FBG sensor was used to monitor the absorption process and hygroscopic response of the hardened and dried biocement when exposed to a liquid/humid environment. From the FBG-based calculated hygric strains as a function of moisture concentration, the coefficient of moisture expansion (CME) of the examined bone cement was obtained, exhibiting two distinct linear regions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. rhBMP-2 release from injectable poly(DL-lactic-co-glycolic acid)/calcium-phosphate cement composites.

    NARCIS (Netherlands)

    Ruhe, P.Q.; Hedberg, E.L.; Padron, N.T.; Spauwen, P.H.M.; Jansen, J.A.; Mikos, A.G.

    2003-01-01

    BACKGROUND: In bone tissue engineering, poly(DL-lactic-co-glycolic acid) (PLGA) microparticles are frequently used as a delivery vehicle for bioactive molecules. Calcium phosphate cement is an injectable, osteoconductive, and degradable bone cement that sets in situ. The objective of this study was

  10. Nano clay-enhanced calcium phosphate cements and hydrogels for biomedical applications

    Science.gov (United States)

    Jammalamadaka, Udayabhanu

    Biomaterials are used as templates for drug delivery, scaffolds in tissue engineering, grafts in surgeries, and support for tissue regeneration. Novel biomaterial composites are needed to meet multifaceted requirements of compatibility, ease of fabrication and controlled drug delivery. Currently used biomaterials in orthopedics surgeries suffer limitations in toxicity and preventing infections. Polymethyl methacrylate (PMMA) used as bone cement suffers from limitations of thermal necrosis and monomer toxicity calls for development of better cementing biomaterials. A biodegradable/bioresorbable cement with good mechanical properties is needed to address this short coming. Metal implants used in fixing fractures or total joint replacement needs improvements in preventing biofilm formation and better tissue integration. This research addressed the above mentioned research gaps by formulating novel biomaterial composites. Calcium phosphate cements are the alternative bone cements that are bioresorbable and promote tissue integration. These cements lack sufficient mechanical strengths to be used in load bearing sites. The addition of nanoparticles is hypothesized to improve the mechanical properties without inducing toxicity to the tissue. This hypothesis was tested by evaluating compression and flexural strengths in addition to cytocompatibility tests. Results indicate that addition of nano-clay particles (halloysites nanotubes) improved the compressive strength and osteoinductive properties of calcium phosphate cements. To address the research need of preventing implant failure due to infection and aseptic loosening, novel coatings are needed. Hydrogels are well establish for their ability to mimic in vivo environment, promote cell viability and as drug delivery vehicles. Use of composites of hydrogels and drug-loaded nanoparticles to prevent infection was evaluated. Cytocompatibility results indicate good cell viability. Antibacterial results show sustained release

  11. Incorporation of fast dissolving glucose porogens into an injectable calcium phosphate cement for bone tissue engineering.

    Science.gov (United States)

    Smith, Brandon T; Santoro, Marco; Grosfeld, Eline C; Shah, Sarita R; van den Beucken, Jeroen J J P; Jansen, John A; Mikos, Antonios G

    2017-03-01

    Calcium phosphate cements (CPCs) have been extensively investigated as scaffolds in bone tissue engineering in light of their chemical composition closely resembling the mineral component of bone extracellular matrix. Yet, the degradation kinetics of many CPCs is slow compared to de novo bone formation. In order to overcome this shortcoming, the use of porogens within CPCs has been suggested as a potential strategy to increase scaffold porosity and promote surface degradation. This study explored the usage of glucose microparticles (GMPs) as porogens for the introduction of macroporosity within CPCs, and characterized the handling properties and physicochemical characteristics of CPCs containing GMPs. Samples were fabricated with four different weight fractions of GMPs (10, 20, 30, and 40%) and two different size ranges (100-150μm and 150-300μm), and were assayed for porosity, pore size distribution, morphology, and compressive mechanical properties. Samples were further tested for their handling properties - specifically, setting time and cohesiveness. Additionally, these same analyses were conducted on samples exposed to a physiological solution in order to estimate the dissolution kinetics of GMPs and its effect on the properties of the composite. GMPs were efficiently encapsulated and homogeneously dispersed in the resulting composite. Although setting times increased for GMP/CPC formulations compared to control CPC material, increasing the Na 2 HPO 4 concentration in the liquid phase decreased the initial setting time to clinically acceptable values (i.e. introduction of GMPs into CPC resulted in macroporous scaffolds with good handling properties, as well as designer porosity and pore size distribution via selection of the appropriate size/weight fraction of GMPs. The data demonstrate that GMPs are promising porogens for the production of highly tunable porous CPC scaffolds. Calcium phosphate cements have shown great promise for the regeneration of bone

  12. Calcium phosphate holmium-166 ceramic to addition in bone cement: synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Donanzam, Blanda A.; Campos, Tarcisio P.R., E-mail: campos@nuclear.ufmg.b [Universidade do Federal de Minas Gerais (DEN/UFMG), Belo Horizonte, MG (Brazil). Escola de Engenharia. Dept. de Engenharia Nuclear; Dalmazio, Ilza; Valente, Eduardo S., E-mail: id@cdtn.b, E-mail: valente@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2011-07-01

    Spine metastases are a common and painful complication of cancer. The treatment often consists of bone cement injection (vertebroplasty or kyphoplasty) within vertebral body for vertebrae stabilization, followed by external beam radiation therapy. Recently, researchers introduced the concept of radioactive bone cement for spine tumors therapy. Then, investigations about bioactive and radioactive materials became interesting. In this study, we present the synthesis of calcium phosphate incorporated holmium (CaP-Ho) via sol-gel technique, and its characterization by XRD, FT-IR, NA and SEM. Results showed a multiphasic bioceramic composed mainly of hydroxyapatite, {beta}-tricalcium phosphate, holmium phosphate and traces of calcium pyrophosphate. Furthermore, the nuclide Ho-166 was the major radioisotope produced. Despite that, the radioactive bioceramic CaP-{sup 166}Ho must be investigated in clinical trials to assure its efficacy and safety on spine tumors treatment (author)

  13. Nanostructural Deformation Analysis of Calcium Silicate Hydrate in Portland Cement Paste by Atomic Pair Distribution Function

    OpenAIRE

    Suzuki, Hiroshi; Bae, Sungchul; Kanematsu, Manabu

    2016-01-01

    The deformation of nanostructure of calcium silicate hydrate (C-S-H) in Portland cement (PC) paste under compression was characterized by the atomic pair distribution function (PDF), measured using synchrotron X-ray diffraction. The PDF of the PC paste exhibited a unique deformation behavior for a short-range order below 2.0 nm, close to the size of the C-S-H globule, while the deformation for a long-range order was similar to that of a calcium hydroxide phase measured by Bragg peak shift. Th...

  14. The use of calcium phosphate cement paste for the correction of the depressed nose deformity.

    Science.gov (United States)

    Hatoko, Mitsuo; Tada, Hideyuki; Tanaka, Aya; Yurugi, Satoshi; Niitsuma, Katsunori; Iioka, Hiroshi

    2005-03-01

    The authors report the use of calcium phosphate cement paste as a material for correction of depression after nasal bone fracture, and evaluate its usefulness. Biopex R (Mitsubishi Material Corporation, Tokyo, Japan) was used in this study as calcium phosphate cement (CPC), which was developed in Japan. CPC injection was used in six patients (four women and two men) with depressed nose deformity after nasal bone fracture. The patients' ages ranged from 29 to 67 years (mean, 49 years), and the follow-up period ranged from 12 to 27 months. The amount of injected cement varied from 0.5 to 2.5 mL, approximately. There was no postoperative infection or allergic reaction in any patient. Clinical and X-ray photography findings showed that a reduction in volume of the injected cement occurred gradually as long as 7 to 8 months after surgery. After that period, the volume was mostly maintained. It seemed that the degree of reduction was approximately 10% to 15% of the original volume. Satisfactory results were obtained in all cases. The authors conclude that the use of CPC is an option for the correction of depressed nose deformity and that its application must be determined in each case, considering its advantages and disadvantages.

  15. Particle size of a new endodontic cement compared to Root MTA and calcium hydroxide

    Science.gov (United States)

    Soheilipour, Elham; Kheirieh, Sanam; Madani, Majid; Akbarzadeh Baghban, Alireza; Asgary, Saeed

    2009-01-01

    INTRODUCTION: Particle size and distribution can influence the properties of materials. This study analyzed and compared the particle size of Root MTA, calcium hydroxide (CH), and a new endodontic cement called calcium enriched material (CEM). MATERIALS AND METHODS: The particle size of each material was analyzed three times using 0.05 mg of test material with a particle size analyzer. The particle size distribution ranges, the cumulative percentage and the mean of particle sizes were calculated. One-way ANOVA, Tukey, and Chi-square tests were used for statistical analyses. RESULTS: Results demonstrated that the distribution of particles was dissimilar. Particle mean size in the three different materials was not significantly different. However, the cumulative percentage of CH and CEM cement particles size demonstrated significant difference (P<0.05). Among the various particle size distributions, the particle distribution in the size range of ≤30 μm showed significant difference between materials (P<0.05). Interestingly, the smallest range of particle size belonged to CEM cement. CONCLUSION: The high percentage of small particles found in CEM cement provides desirable properties such as effective seal, good setting time and film thickness in addition to favorable flow and adaptability. PMID:24003332

  16. Preparation, Physical-Chemical Characterization, and Cytocompatibility of Polymeric Calcium Phosphate Cements

    Directory of Open Access Journals (Sweden)

    Rania M. Khashaba

    2011-01-01

    Full Text Available Aim. Physicochemical mechanical and in vitro biological properties of novel formulations of polymeric calcium phosphate cements (CPCs were investigated. Methods. Monocalcium phosphate, calcium oxide, and synthetic hydroxyapatite were combined with either modified polyacrylic acid, light activated polyalkenoic acid, or polymethyl vinyl ether maleic acid to obtain Types I, II, and III CPCs. Setting time, compressive and diametral strength of CPCs was compared with zinc polycarboxylate cement (control. Specimens were characterized using X-ray diffraction, scanning electron microscopy, and infrared spectroscopy. In vitro cytotoxicity of CPCs and control was assessed. Results. X-ray diffraction analysis showed hydroxyapatite, monetite, and brushite. Acid-base reaction was confirmed by the appearance of stretching peaks in IR spectra of set cements. SEM revealed rod-like crystals and platy crystals. Setting time of cements was 5–12 min. Type III showed significantly higher strength values compared to control. Type III yielded high biocompatibility. Conclusions. Type III CPCs show promise for dental applications.

  17. Analysis of the color alteration and radiopacity promoted by bismuth oxide in calcium silicate cement

    Directory of Open Access Journals (Sweden)

    Marina Angelica Marciano

    2013-07-01

    Full Text Available The aim of the study was to determine if the increase in radiopacity provided by bismuth oxide is related to the color alteration of calcium silicate-based cement. Calcium silicate cement (CSC was mixed with 0%, 15%, 20%, 30% and 50% of bismuth oxide (BO, determined by weight. Mineral trioxide aggregate (MTA was the control group. The radiopacity test was performed according to ISO 6876/2001. The color was evaluated using the CIE system. The assessments were performed after 24 hours, 7 and 30 days of setting time, using a spectrophotometer to obtain the ΔE, Δa, Δb and ΔL values. The statistical analyses were performed using the Kruskal-Wallis/Dunn and ANOVA/Tukey tests (p 3 mm equivalent of Al. The MTA group was statistically similar to the CSC / 30% BO group (p > 0.05. In regard to color, the increase of bismuth oxide resulted in a decrease in the ΔE value of the calcium silicate cement. The CSC group presented statistically higher ΔE values than the CSC / 50% BO group (p < 0.05. The comparison between 24 hours and 7 days showed higher ΔE for the MTA group, with statistical differences for the CSC / 15% BO and CSC / 50% BO groups (p < 0.05. After 30 days, CSC showed statistically higher ΔE values than CSC / 30% BO and CSC / 50% BO (p < 0.05. In conclusion, the increase in radiopacity provided by bismuth oxide has no relation to the color alteration of calcium silicate-based cements.

  18. Graphene Nanosheets to Improve Physico-Mechanical Properties of Bioactive Calcium Silicate Cements

    Directory of Open Access Journals (Sweden)

    Nileshkumar Dubey

    2017-05-01

    Full Text Available Bioactive calcium silicate cements are widely used to induce mineralization, to cement prosthetic parts, in the management of tooth perforations, and other areas. Nonetheless, they can present clinical disadvantages, such as long setting time and modest physico-mechanical properties. The objective of this work was to evaluate the potential of graphene nanosheets (GNS to improve two bioactive cements. GNS were obtained via reduction of graphite oxide. GNS were mixed (1, 3, 5, and 7 wt % with Biodentine (BIO and Endocem Zr (ECZ, and the effects on setting time, hardness, push-out strength, pH profile, cell proliferation, and mineralization were evaluated. Statistics were performed with two-way ANOVA and Tukey test (α = 0.05. GNS has not interfered in the composition of the set cements as confirmed by Raman, FT-IR and XRD. GNS (1 and 3 wt % shortened the setting time, increased hardness of both materials but decreased significantly the push-out strength of ECZ. pH was not affected but 1 wt % and 7 wt % to ECZ and 5 wt % to BIO increased the mineralization compared to the controls. In summary, GNS may be an alternative to improve the physico-mechanical properties and bioactivity of cements. Nonetheless, the use of GNS may not be advised for all materials when effective bonding is a concern.

  19. Effects of Chlorhexidine and Sodium Hypochlorite on the Setting Time of Calcium-Enriched Mixture Cement.

    Science.gov (United States)

    Frough Reyhani, Mohammad; Ghasemi, Negin; Shakouie, Sahar; Rahimi, Saeed; Salem Milani, Amin; Ranjbar, Babak

    2015-01-01

    The aim of the present study was to evaluate whether adding 2% chlorhexidine (CHX) and 2.6% sodium hypochlorite (NaOCl) to calcium-enriched mixture (CEM) cement would affect its setting time (ST), or not. In this study, the setting time of CEM cement was evaluated in three groups (n=9) as follows: group 1; CEM cement, group 2; CEM cement+2% CHX and group 3; CEM cement+2.6% NaOCl. Then the mean values of ST were calculated and the Kolmogorov-Smirnov test was used to evaluate the normal distribution of data. The Kruskal-Wallis and Mann-Whitney U tests were used for statistical analysis. Statistical significance was set at 0.05. The mean ST for groups 1, 2 and 3 were 105, 120 and 220 min, respectively. There was a significant increase in the duration of ST in group 3 (NaOCl) in comparison with the two other groups (Pchlorhexidine did not alter the ST.

  20. A New Type of Biphasic Calcium Phosphate Cement as a Gentamicin Carrier for Osteomyelitis

    Directory of Open Access Journals (Sweden)

    Wen-Yu Su

    2013-01-01

    Full Text Available Osteomyelitis therapy is a long-term and inconvenient procedure for a patient. Antibiotic-loaded bone cements are both a complementary and alternative treatment option to intravenous antibiotic therapy for the treatment of osteomyelitis. In the current study, the biphasic calcium phosphate cement (CPC, called α-TCP/HAP (α-tricalcium phosphate/hydroxyapatite biphasic cement, was prepared as an antibiotics carrier for osteomyelitis. The developed biphasic cement with a microstructure of α-TCP surrounding the HAP has a fast setting time which will fulfill the clinical demand. The X-ray diffraction and Fourier transform infrared spectrometry analyses showed the final phase to be HAP, the basic bone mineral, after setting for a period of time. Scanning electron microscopy revealed a porous structure with particle sizes of a few micrometers. The addition of gentamicin in α-TCP/HAP would delay the transition of α-TCP but would not change the final-phase HAP. The gentamicin-loaded α-TCP/HAP supplies high doses of the antibiotic during the initial 24 hours when they are soaked in phosphate buffer solution (PBS. Thereafter, a slower drug release is produced, supplying minimum inhibitory concentration until the end of the experiment (30 days. Studies of growth inhibition of Staphylococcus aureus and Pseudomonas aeruginosa in culture indicated that gentamicin released after 30 days from α-TCP/HAP biphasic cement retained antibacterial activity.

  1. Effects of glass fiber modified with calcium silicate hydrate (C-S-H(I)) reinforced cement

    Science.gov (United States)

    Xin, M.; Zhang, L.; Ge, S.; Cheng, X.

    2017-03-01

    In this paper, calcium silicate hydrate (C-S-H(I)) and glass fiber modified with C-S-H(I) (SiF) at ambient temperature were synthesized. SiF and untreated fiber (OF) were incorporated into cement paste. Phase composition of C-S-H(I), SiF and OF was characterized by XRD. The surface morphologies were characterized by SEM. Flexural performance of fiber reinforced cement (FRC) at different curing ages was investigated. Results indicated that both SiF and OF could reinforce cement paste. SiF had a more positive effect on improving the flexural performance of FRC than OF. The strength of SiF reinforced cement was 11.48MPa after 28 days curing when fiber volume was 1.0%, 12.55% higher than that of OF reinforced cement. The flexural strength increased with the addition of fiber volume. However, the large dosage of fiber might cause a decrease in flexural strength of FRC.

  2. Evaluation of the sealing ability of bone cement as furcation perforation repair material when compared with mineral trioxide aggregate and calcium phosphate cement: An in-vitro study

    Directory of Open Access Journals (Sweden)

    Rashmi Chordiya

    2010-01-01

    Full Text Available Aim: This study was undertaken to compare the sealing ability of bone cement as furcation perforation repair material when compared with mineral trioxide aggregate and calcium phosphate cement. Materials and Methods: A total of 70 sound mandibular molars were selected for this study. The sample teeth were randomly divided into five groups: group I - n=20, perforation repair material used, mineral trioxide aggregate; group II - n=20, perforation repair material used, calcium phosphate cement; group III - n=20, perforation repair material used, bone cement; group IV - positive control, n=5, the furcation were not repaired with any material; group V - negative control, n=5, furcation area intact, no perforation done. The teeth were immersed in silver nitrate solution for 2 hours and then rinsed with photographic developer solution for 6 hours. They were then sectioned in a longitudinal direction and examined under a stereomicroscope. In each section the actual values of dye leakage were calculated from outer margins of perforation to the level of pulpal floor and were then subjected to statistical analysis. Results: An unpaired ′t′ test revealed that different groups exhibited significantly different dye penetrations (P<0.01. Conclusion: Furcation perforation repaired with MTA showed minimum microleakage (mean 54.5%, calcium phosphate cement showed maximum microleakage (100%, and bone cement showed moderate dye leakage (87.8%.

  3. Effects of Leaching Behavior of Calcium Ions on Compression and Durability of Cement-Based Materials with Mineral Admixtures

    Science.gov (United States)

    Cheng, An; Chao, Sao-Jeng; Lin, Wei-Ting

    2013-01-01

    Leaching of calcium ions increases the porosity of cement-based materials, consequently resulting in a negative effect on durability since it provides an entry for aggressive harmful ions, causing reinforcing steel corrosion. This study investigates the effects of leaching behavior of calcium ions on the compression and durability of cement-based materials. Since the parameters influencing the leaching behavior of cement-based materials are unclear and diverse, this paper focuses on the influence of added mineral admixtures (fly ash, slag and silica fume) on the leaching behavior of calcium ions regarding compression and durability of cemented-based materials. Ammonium nitrate solution was used to accelerate the leaching process in this study. Scanning electron microscopy, X-ray diffraction analysis, and thermogravimetric analysis were employed to analyze and compare the cement-based material compositions prior to and after calcium ion leaching. The experimental results show that the mineral admixtures reduce calcium hydroxide quantity and refine pore structure through pozzolanic reaction, thus enhancing the compressive strength and durability of cement-based materials. PMID:28809247

  4. Cytotoxicity and Osteogenic Potential of Silicate Calcium Cements as Potential Protective Materials for Pulpal Revascularization

    Science.gov (United States)

    Bortoluzzi, Eduardo A.; Niu, Li-na; Palani, Chithra D.; El-Awady, Ahmed R.; Hammond, Barry D.; Pei, Dan-dan; Tian, Fu-cong; Cutler, Christopher W.; Pashley, David H.; Tay, Franklin R.

    2016-01-01

    Objectives In pulpal revascularization, a protective material is placed coronal to the blood clot to prevent recontamination and to facilitate osteogenic differentiation of mesenchynal stem cells to produce new dental tissues. Although mineral trioxide aggregate (MTA) has been the material of choice for clot protection, it is easily displaced into the clot during condensation. The present study evaluated the effects of recently-introduced calcium silicate cements (Biodentine and TheraCal LC) on the viability and osteogenic differentiation of human dental pulp stem cells (hDPSCs) by comparing with MTA Angelus. Methods Cell viability was assessed using XTT assay and flow cytometry. The osteogenic potential of hDPSCs exposed to calcium silicate cements was examined using qRT-PCR for osteogeic gene expressions, alkaline phosphatase enzyme activity, Alizarin red S staining and transmission electron microscopy of extracellular calcium deposits. Parametric statistical methods were employed for analyses of significant difference among groups, with α=0.05. Results The cytotoxic effects of Biodentine and TheraCal LC on hDPSCs were time- and concentration-dependent. Osteogenic differentiation of hDPSCs was enhanced after exposure to Biodentine that was depleted of its cytotoxic components. This effect was less readily observed in hDPSCs exposed to TheraCal LC, although both cements supported extracelluar mineralization better than the positive control (zinc oxide-eugenol–based cement). Significance A favorable tissue response is anticipated to occur with the use of Biodentine as a blood clot-protecting material for pulpal revascularizaiton. Further investigations with the use of in vivo animal models are required to validate the potential adverse biological effects of TheraCal LC on hDPSCs. PMID:26494267

  5. Cytotoxicity and osteogenic potential of silicate calcium cements as potential protective materials for pulpal revascularization.

    Science.gov (United States)

    Bortoluzzi, Eduardo A; Niu, Li-Na; Palani, Chithra D; El-Awady, Ahmed R; Hammond, Barry D; Pei, Dan-Dan; Tian, Fu-Cong; Cutler, Christopher W; Pashley, David H; Tay, Franklin R

    2015-12-01

    In pulpal revascularization, a protective material is placed coronal to the blood clot to prevent recontamination and to facilitate osteogenic differentiation of mesenchymal stem cells to produce new dental tissues. Although mineral trioxide aggregate (MTA) has been the material of choice for clot protection, it is easily displaced into the clot during condensation. The present study evaluated the effects of recently introduced calcium silicate cements (Biodentine and TheraCal LC) on the viability and osteogenic differentiation of human dental pulp stem cells (hDPSCs) by comparing with MTA Angelus. Cell viability was assessed using XTT assay and flow cytometry. The osteogenic potential of hDPSCs exposed to calcium silicate cements was examined using qRT-PCR for osteogenic gene expressions, alkaline phosphatase enzyme activity, Alizarin red S staining and transmission electron microscopy of extracellular calcium deposits. Parametric statistical methods were employed for analyses of significant difference among groups, with α=0.05. The cytotoxic effects of Biodentine and TheraCal LC on hDPSCs were time- and concentration-dependent. Osteogenic differentiation of hDPSCs was enhanced after exposure to Biodentine that was depleted of its cytotoxic components. This effect was less readily observed in hDPSCs exposed to TheraCal LC, although both cements supported extracellular mineralization better than the positive control (zinc oxide-eugenol-based cement). A favorable tissue response is anticipated to occur with the use of Biodentine as a blood clot-protecting material for pulpal revascularization. Further investigations with the use of in vivo animal models are required to validate the potential adverse biological effects of TheraCal LC on hDPSCs. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  6. The effect of injectable calcium phosphate cement on bone anchorage of titanium implants: an experimental feasibility study in dogs.

    NARCIS (Netherlands)

    Arisan, V.; Anil, A.; Wolke, J.G.C.; Ozer, K.

    2010-01-01

    Calcium phosphate has high osteotransductive potential. The injectable form of calcium phosphate cement (ICAP) can be used as an adjunctive supportive agent for dental implants. The aim of this study was to assess the effect of an ICAP on the reverse torque resistance of titanium implants. Two

  7. The Retentive Strength of Cemented Zirconium Oxide Crowns after Dentin Pretreatment with Desensitizing Paste Containing 8% Arginine and Calcium Carbonate

    Directory of Open Access Journals (Sweden)

    Raphael Pilo

    2016-03-01

    Full Text Available The effect of dentin pretreatment with Desensitizing Paste containing 8% arginine and calcium carbonate on the retention of zirconium oxide (Y-TZP crowns was tested. Forty molar teeth were mounted and prepared using a standardized protocol. Y-TZP crowns were produced using computer-aided design and computer-aided manufacturing (CAD-CAM technology. The 40 prepared teeth were either pretreated with Desensitizing Paste or not pretreated. After two weeks, each group was subdivided into two groups, cemented with either Resin Modified Glass Ionomer Cement (RMGIC or Self Adhesive Resin Cement (SARC. Prior to cementation, the surface areas of the prepared teeth were measured. After aging, the cemented crown-tooth assemblies were tested for retentive strength using a universal testing machine. The debonded surfaces of the teeth and crowns were examined microscopically at 10× magnification. Pretreating the dentin surfaces with Desensitizing Paste prior to cementation did not affect the retention of the Y-TZP crowns. The retentive values for RMGIC (3.04 ± 0.77 MPa were significantly higher than those for SARC (2.28 ± 0.58 MPa. The predominant failure modes for the RMGIC and SARC were adhesive cement-dentin and adhesive cement-crown, respectively. An 8.0% arginine and calcium carbonate in-office desensitizing paste can be safely used to reduce post-cementation sensitivity without reducing the retentive strength of Y-TZP crowns.

  8. The Retentive Strength of Cemented Zirconium Oxide Crowns after Dentin Pretreatment with Desensitizing Paste Containing 8% Arginine and Calcium Carbonate.

    Science.gov (United States)

    Pilo, Raphael; Harel, Noga; Nissan, Joseph; Levartovsky, Shifra

    2016-03-25

    The effect of dentin pretreatment with Desensitizing Paste containing 8% arginine and calcium carbonate on the retention of zirconium oxide (Y-TZP) crowns was tested. Forty molar teeth were mounted and prepared using a standardized protocol. Y-TZP crowns were produced using computer-aided design and computer-aided manufacturing (CAD-CAM) technology. The 40 prepared teeth were either pretreated with Desensitizing Paste or not pretreated. After two weeks, each group was subdivided into two groups, cemented with either Resin Modified Glass Ionomer Cement (RMGIC) or Self Adhesive Resin Cement (SARC)). Prior to cementation, the surface areas of the prepared teeth were measured. After aging, the cemented crown-tooth assemblies were tested for retentive strength using a universal testing machine. The debonded surfaces of the teeth and crowns were examined microscopically at 10× magnification. Pretreating the dentin surfaces with Desensitizing Paste prior to cementation did not affect the retention of the Y-TZP crowns. The retentive values for RMGIC (3.04 ± 0.77 MPa) were significantly higher than those for SARC (2.28 ± 0.58 MPa). The predominant failure modes for the RMGIC and SARC were adhesive cement-dentin and adhesive cement-crown, respectively. An 8.0% arginine and calcium carbonate in-office desensitizing paste can be safely used to reduce post-cementation sensitivity without reducing the retentive strength of Y-TZP crowns.

  9. Shear bond strength of novel calcium aluminate-based cement (EndoBinder) to root dentine

    Science.gov (United States)

    Garcia, Lucas da Fonseca Roberti; Rossetto, Hebert Luis; Pires-de-Souza, Fernanda de Carvalho Panzeri

    2014-01-01

    Objective: To evaluate the shear bond strength of a novel calcium aluminate-based cement, EndoBinder (EB), to dentine in comparison with Grey and White Mineral Trioxide Aggregate (MTA). Materials and Methods: Root canal hemi-sections obtained from 30 extracted molar teeth were embedded in self-polymerized acrylic resin and were grounded wet in order to obtain a flat dentine surface. Next, the roots were randomly assigned into three groups (n = 10), according to the cement used, as follows: EB: EndoBinder; WMTA: White MTA and GMTA: Grey MTA. The shear bond strength test was performed using a Universal Testing Machine (0.5 mm/min) and the data were submitted to statistical analysis (1-way ANOVA and Tukey tests, P 0.05). WMTA presented the lowest mean values, which were significant in comparison with EB (P < 0.05). Conclusions: The novel calcium aluminate-based cement presented higher shear bond strength than WMTA, and should be considered as a promising alternative in endodontic therapy. PMID:25512731

  10. Compressive Strength of Mineral Trioxide Aggregate and Calcium-enriched Mixture Cement Mixed with Propylene Glycol.

    Science.gov (United States)

    Sobhnamayan, Fereshte; Adl, Alireza; Shojaee, Nooshin Sadat; Sedigh-Shams, Mahdi; Zarghami, Elnaz

    2017-01-01

    The aim of the present study was to evaluate and compare the compressive strength (CS) of mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cement when mixed with propylene glycol (PG). Twenty four custom-made split molds with 5 holes in each were prepared. Molds were allocated into eight groups (n=15 holes) as follows: Groups 1,5: CEM and MTA mixed with PG (100%), Groups 2,6: CEM and MTA mixed with PG (20% )+CEM or MTA liquid (80%) respectively, Groups 3,7: CEM and MTA mixed with PG (50% )+CEM or MTA liquid (50% ) respectively, Groups 4,8: CEM and MTA mixed with CEM or MTA liquid respectively as control groups. All specimens were kept in 37°C in an incubator and the compressive strength was evaluated after 7 days. Data were analyzed using the Kruskal Wallis and Dunne tests. The level of significance was set at 0.05. In all concentration of PG, MTA samples showed better results than CEM cement. In CEM samples, adding 20% PG could significantly increase the compressive strength in comparison with control group and 100% PG (P=0.047 and P=0.011, respectively). In MTA samples, adding 100% and 50% PG significantly increased the compressive strength of the cement in comparison with control group (P=0.037 and, P=0.005, respectively). Considering the limitations of the present study, appropriate concentration of PG could improve the CS of MTA and CEM cement.

  11. Properties of Chemically Combusted Calcium Carbide Residue and Its Influence on Cement Properties

    Directory of Open Access Journals (Sweden)

    Hongfang Sun

    2015-02-01

    Full Text Available Calcium carbide residue (CCR is a waste by-product from acetylene gas production. The main component of CCR is Ca(OH2, which can react with siliceous materials through pozzolanic reactions, resulting in a product similar to those obtained from the cement hydration process. Thus, it is possible to use CCR as a substitute for Portland cement in concrete. In this research, we synthesized CCR and silica fume through a chemical combustion technique to produce a new reactive cementitious powder (RCP. The properties of paste and mortar in fresh and hardened states (setting time, shrinkage, and compressive strength with 5% cement replacement by RCP were evaluated. The hydration of RCP and OPC (Ordinary Portland Cement pastes was also examined through SEM (scanning electron microscope. Test results showed that in comparison to control OPC mix, the hydration products for the RCP mix took longer to formulate. The initial and final setting times were prolonged, while the drying shrinkage was significantly reduced. The compressive strength at the age of 45 days for RCP mortar mix was found to be higher than that of OPC mortar and OPC mortar with silica fume mix by 10% and 8%, respectively. Therefore, the synthesized RCP was proved to be a sustainable active cementitious powder for the strength enhanced of building materials, which will result in the diversion of significant quantities of this by-product from landfills.

  12. Intracanal management of a post traumatic perforative invasive cervical root resorption using calcium enriched matrix cement

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    Saeed Asgary

    2013-01-01

    Full Text Available Invasive cervical root resorption (ICR is a consequence of a resorptive soft-tissue penetrating into dentin that starts below the gingival attachment and tends to be asymptomatic unless dental pulp involvement. Prompt diagnosis is the key to retention of the involved tooth. Treatment procedure includes non-surgical elimination of the resorptive soft-tissues and restoration of the cavity. In case of pulp involvement, endodontic treatment is indicated. This is a report of a non-surgical intra canal treatment case in a maxillary central incisor, which involved the pulp and was successfully treated with calcium enriched mixture (CEM cement. Based on favorable long-term treatment outcomes, CEM cement may be a promising biomaterial in treatment of ICR cases.

  13. [Endodontics in motion: new concepts, materials and techniques 1. Hydraulic Calcium Silicate Cements].

    Science.gov (United States)

    Moinzadeh, A T; Jongsma, L; de Groot-Kuin, D; Cristescu, R; Neirynck, N; Camilleri, J

    2015-01-01

    Hydraulic Calcium Silicate Cements (HCSCs) constitute a group of materials that have become increasingly popular in endodontics since the introduction of Mineral Trioxide Aggregate (MTA) in the 1990s. MTA is Portland cement to which bismuth oxide has been added to increase its radiopacity. The most important property of MTA is its capacity to set in water or a humid environment. However, MTA also has important limitations, for example, it's difficult to work with and can discolour teeth. Recently, numerous products based on HCSC chemistry, which can be considered as modifications of MTA intended to reduce its limitations, have become available on the market. Despite their potential advantages, all of these materials have their own specific limitations that are currently insufficiently known and investigated.

  14. The progress of early phase bone healing using porous granules produced from calcium phosphate cement

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    Jungbluth P

    2010-05-01

    Full Text Available Abstract Objective Bone grafting is a vital component in many surgical procedures to facilitate the repair of bone defects or fusions. Autologous bone has been the gold standard to date in spite of associated donor-site morbidity and the limited amount of available donor bone. The aim of this study was to investigate the progress of bone regeneration and material degradation of calcium phosphate granules (CPG produced from a calcium phosphate self-setting cement powder compared to the use of autologous bone grafting in the treatment of "critical size defects" on load-bearing long bones of minipigs. Methods A critical size defect in the tibial metaphysis of 16 mini-pigs was filled either with autologous cancellous graft or with micro- and macroporous carbonated, apatic calcium phosphate granules (CPG produced from a calcium phosphate self-setting cement powder. After 6 weeks, the specimens were assessed by X-ray and histological evaluation. The amount of new bone formation was analysed histomorphometrically. Results The semi-quantitative analysis of the radiological results showed a complete osseous bridging of the defect in three cases for the autograft group. In the same group five animals showed a beginning, but still incomplete bridging of the defect, whereas in the CPG group just two animals developed this. All other animals of the CPG group showed only a still discontinuous new bone formation. Altogether, radiologically a better osseous bridging was observed in the autograft group compared to the CPG group. Histomorphometrical analysis after six weeks of healing revealed that the area of new bone was significantly greater in the autograft group concerning the central area of the defect zone (p Conclusions Within the limits of the present study it could be demonstrated that autologous cancellous grafts lead to a significantly better bone regeneration compared to the application of calcium phosphate granules (CPG produced from a calcium

  15. Development and characterization of an injectable cement of nano calcium-deficient hydroxyapatite/multi(amino acid) copolymer/calcium sulfate hemihydrate for bone repair

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    Qi, Xiaotong; Li, Hong; Qiao, Bo; Li, Weichao; Hao, Xinyan; Wu, Jun; Su, Bao; Jiang, Dianming

    2013-01-01

    A novel injectable bone cement was developed by integration of nano calcium-deficient hydroxyapatite/multi(amino acid) copolymer (n-CDHA/MAC) and calcium sulfate hemihydrate (CSH; CaSO4 · 1/2H2O). The structure, setting time, and compressive strength of the cement were investigated. The results showed that the cement with a liquid to powder ratio of 0.8 mL/g exhibited good injectability and appropriate setting time and mechanical properties. In vitro cell studies indicated that MC3T3-E1 cells cultured on the n-CDHA/MAC/CSH composite spread well and showed a good proliferation state. The alkaline phosphatase activity of the MC3T3-E1 cells cultured on the n-CDHA/MAC/CSH composite was significantly higher than that of the cells on pure CSH at 4 and 7 days of culture. The n-CDHA/MAC/CSH cement was implanted into critical size defects of the femoral condyle in rabbits to evaluate its biocompatibility and osteogenesis in vivo. Radiological and histological results indicated that introduction of the n-CDHA/MAC into CSH enhanced new bone formation, and the n-CDHA/MAC/CSH cement exhibited good biocompatibility and degradability. In conclusion, the injectable n-CDHA/MAC/CSH composite cement has a significant clinical advantage over pure CSH cement, and may be a promising bone graft substitute for the treatment of bone defects. PMID:24293996

  16. Postextraction socket grafting using calcium phosphate cement and platelet rich fibrin

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    Nihal Devkar

    2014-01-01

    Full Text Available This clinical case report describes and demonstrates the successful use of calcium phosphate cement (CPC in conjunction with platelet-rich fibrin (PRF for postextraction socket grafting in maxillary right first premolar area. CPC can be molded to form a scaffold. It has been used previously for regeneration in intrabony defects, but very few clinical studies in humans have reported its use for socket grafting. In this report, we have presented a novel use of CPC in conjunction with PRF for ridge preservation after tooth extraction.

  17. Characterization of set Intermediate Restorative Material, Biodentine, Bioaggregate and a prototype calcium silicate cement for use as root-end filling materials.

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    Grech, L; Mallia, B; Camilleri, J

    2013-07-01

    To investigate the composition of materials and leachate of a hydrated prototype cement composed of tricalcium silicate and radiopacifier and compare this to other tricalcium silicate-based cements (Biodentine and Bioaggregate) to assess whether the additives in the proprietary brand cements affect the hydration of the materials, using Intermediate Restorative Material (IRM), a standard root-end filling material as a control. The materials investigated included a prototype-radiopacified tricalcium silicate cement, Biodentine, Bioaggregate and Intermediate Restorative Material (IRM). The pH and calcium ion concentration of the leachate were investigated. The hydrated cements were characterized using scanning electron microscopy (SEM) and X-ray energy dispersive analysis (EDX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). All the cements tested were alkaline. The tricalcium silicate-based cements leached calcium in solution. Scanning electron microscopy of the prototype-radiopacified tricalcium silicate cement, Biodentine and Bioaggregate displayed hydrating cement grains, surrounded by a matrix composed of calcium silicate hydrate and calcium hydroxide. The presence of calcium hydroxide was evident from the XRD plots. FT-IR indicated the occurrence of a poorly crystalline calcium silicate hydrate. Biodentine displayed the presence of calcium carbonate. Bioaggregate incorporated a phosphate-containing phase. IRM consisted of zinc oxide interspersed in an organic matrix. The hydration of prototype-radiopacified tricalcium silicate cement, Biodentine and Bioaggregate resulted in the formation of calcium silicate hydrate and calcium hydroxide, which was leached in solution. The hydrated materials were composed of a cementitous phase that was rich in calcium and silicon and a radiopacifying material. Biodentine included calcium carbonate, and Bioaggregate included silica and calcium phosphate in the powders. IRM was composed of zinc oxide

  18. Assessment of bone healing ability of calcium phosphate cements loaded with platelet lysate in rat calvarial defects.

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    Babo, Pedro S; Carvalho, Pedro P; Santo, Vítor E; Faria, Susana; Gomes, Manuela E; Reis, Rui L

    2016-11-01

    Injectable calcium phosphate cements have been used as a valid alternative to autologous bone grafts for bone augmentation with the additional advantage of enabling minimally invasive implantation procedures and for perfectly fitting the tissue defect. Nevertheless, they have low biodegradability and lack adequate biochemical signaling to promote bone healing and remodeling. In previous in vitro studies, we observed that the incorporation of platelet lysate directly into the cement paste or loaded in hyaluronic acid microspheres allowed to modulate the cement degradation and the in vitro expression of osteogenic markers in seeded human adipose derived stem cells. The present study aimed at investigating the possible effect of this system in new bone formation when implanted in calvarial bilateral defects in rats. Different formulations were assessed, namely plain calcium phosphate cements, calcium phosphate cements loaded with human platelet lysate, hybrid injectable formulations composed of the calcium phosphate cement incorporating hyaluronin acid non-loaded microparticles (20% hyaluronin acid) or with particles loaded with platelet lysate. The degradability and new bone regrowth were evaluated in terms of mineral volume in the defect, measured by micro-computed tomography and histomorphometric analysis upon 4, 8 and 12 weeks of implantation. We observed that the incorporation of hyaluronin acid microspheres induced an overly rapid cement degradation, impairing the osteoconductive properties of the cement composites. Moreover, the incorporation of platelet lysate induced higher bone healing than the materials without platelet lysate, up to four weeks after surgery. Nevertheless, this effect was not found to be significant when compared to the one observed in the sham-treated group. © The Author(s) 2016.

  19. Improved workability of injectable calcium sulfate bone cement by regulation of self-setting properties

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Zonggang, E-mail: chenzg@sdu.edu.cn [National Glycoengineering Research Center, Shandong University, Jinan 250100 (China); Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Liu, Huanye [Department of Orthodontics, School of Stomatology, China Medical University, Shenyang 110001 (China); Liu, Xi [Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Lian, Xiaojie [College of Mechanics, Taiyuan University of Technology, Taiyuan 030024 (China); Guo, Zhongwu [National Glycoengineering Research Center, Shandong University, Jinan 250100 (China); Jiang, Hong-Jiang [Wendeng Hospital of Traditional Chinese Orthopedics and Traumatology, Shandong 264400 (China); Cui, Fu-Zhai, E-mail: cuifz@mail.tsinghua.edu.cn [Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2013-04-01

    Calcium sulfate hemihydrate (CSH) powder as an injectable bone cement was prepared by hydrothermal synthesis of calcium sulfate dihydrate (CSD). The prepared materials showed X-ray diffraction peaks corresponding to the CSH structure without any secondary phases, implying complete conversion from CSD phase to CSH phase. Thermogravimetric (TG) analyses showed the crystal water content of CSH was about 6.0% (wt.), which is near to the theoretic crystal water value of CSH. From scanning electron microscopy (SEM) micrographs, sheet crystal structure of CSD was observed to transform into rod-like crystal structure of CSH. Most interesting and important of all, CSD as setting accelerator was also introduced into CSH powder to regulate self-setting properties of injectable CSH paste, and thus the self-setting time of CSH paste can be regulated from near 30 min to less than 5 min by adding various amounts of setting accelerator. Because CSD is not only the reactant of preparing CSH but also the final solidified product of CSH, the setting accelerator has no significant effect on the other properties of materials, such as mechanical properties. In vitro biocompatibility and in vivo histology studies have demonstrated that the materials have good biocompatibility and good efficacy in bone regeneration. All these will further improve the workability of CSH in clinic applications. Highlights: ► Calcium sulfate hemihydrate (CSH) can be an injectable bone cement. ► CSH was produced by hydrothermal synthesis of calcium sulfate dihydrate (CSD). ► CSD was introduced into CSH powder to regulate self-setting properties of CSH. ► Setting accelerator has no significant effect on the other properties of materials. ► Injectable CSH has good biocompatibility and good efficacy in bone regeneration.

  20. Synthesization and characterization of poly(lactic-co-glycolic acid) / calcium phosphate bone cement from crab shells

    Science.gov (United States)

    Hanan, M. R. Abdul; Daud, N. M.; Ismail, L. H.; Saidin, S.

    2017-05-01

    An injectable calcium phosphate (CaP) bone cement has been widely used for musculoskeletal and bone disorder due to its biocompatible and osteoconductive properties. In this study, CaP was successfully synthesized from crab shells by a wet chemical route. Poly(lactic-co-glycolic acid) (PLGA) microspheres which have been produced through a double emulsion technique were incorporated into the CaP mixture for the purpose of bone cement solidification. The ratio of both compounds, CaP and PLGA, were set at 8:2. The CaP and PLGA/CaP bone cement were analyzed by ATR-FTIR, FESEM-EDX and contact angle analyses. The bone cement was composed of CaP and PLGA where the micro-powders of CaP were agglomerated on the PLGA microspheres. Addition of the PLGA has increased the hydrophilicity of the bone cement which will be beneficial for materials degradation and bone integration.

  1. Statistical Analyses of Optimum Partial Replacement of Cement by Fly Ash Based on Complete Consumption of Calcium Hydroxide

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    Ouypornprasert Winai

    2016-01-01

    Full Text Available The objectives of this technical paper were to propose the optimum partial replacement of cement by fly ash based on the complete consumption of calcium hydroxide from hydration reactions of cement and the long-term strength activity index based on equivalent calcium silicate hydrate as well as the propagation of uncertainty due to randomness inherent in main chemical compositions in cement and fly ash. Firstly the hydration- and pozzolanic reactions as well as stoichiometry were reviewed. Then the optimum partial replacement of cement by fly ash was formulated. After that the propagation of uncertainty due to main chemical compositions in cement and fly ash was discussed and the reliability analyses for applying the suitable replacement were reviewed. Finally an applicability of the concepts mentioned above based on statistical data of materials available was demonstrated. The results from analyses were consistent with the testing results by other researchers. The results of this study provided guidelines of suitable utilization of fly ash for partial replacement of cement. It was interesting to note that these concepts could be extended to optimize partial replacement of cement by other types of pozzolan which were described in the other papers of the authors.

  2. Calcium polyphosphate as an additive to zinc-silicate glass ionomer cements.

    Science.gov (United States)

    Valliant, Esther Mae; Gagnier, David; Dickey, Brett Thomas; Boyd, Daniel; Filiaggi, Mark Joseph

    2015-07-01

    Aluminum-free glass ionomer cements (GICs) are under development for orthopedic applications, but are limited by their insufficient handling properties. Here, the addition of calcium polyphosphate (CPP) was investigated as an additive to an experimental zinc-silicate glass ionomer cement. A 50% maximum increase in working time was observed with CPP addition, though this was not clinically significant due to the short working times of the starting zinc-silicate GIC. Surprisingly, CPP also improved the mechanical properties, especially the tensile strength which increased by ∼33% after 30 days in TRIS buffer solution upon CPP addition up to 37.5 wt%. This strengthening may have been due to the formation of ionic crosslinks between the polyphosphate chains and polyacrylic acid. Thus, CPP is a potential additive to future GIC compositions as it has been shown to improve handling and mechanical properties. In addition, CPP may stimulate new bone growth and provide the ability for drug delivery, which are desirable modifications for an orthopedic cement. © The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  3. Vital Pulp Therapy with Calcium-Silicate Cements: Report of Two Cases.

    Science.gov (United States)

    Ashraf, Hengameh; Rahmati, Afsaneh; Amini, Neda

    2017-01-01

    This article describes successful use of calcium-enriched mixture (CEM) cement and Biodentine in apexogenesis treatment in two 8-year-old patients, one with immature permanent molar diagnosed primarily with irreversible pulpitis and the other with partially vital maxillary central incisor. After access cavity preparation, partial pulpotomy in molar and full pulpotomy in central was performed, and the remaining pulps was capped with either Biodentine or CEM cement, in each tooth. The crowns were restored with composite filling material at the following visit. The post-operative radiographic and clinical examinations (approx. average of 16 months) showed that both treated teeth remained functional, with complete root development and apex formation. A calcified bridge was produced underneath the capping material. No further endodontic intervention was necessary. Considering the healing potential of immature vital pulps, the use of CEM cement and Biodentine for apexogenesis might be an applicable choice. These new endodontic biomaterials might be appropriate for vital pulp therapies in an immature tooth. However, further clinical studies with longer follow-up periods are recommended.

  4. 3D plotting of growth factor loaded calcium phosphate cement scaffolds.

    Science.gov (United States)

    Akkineni, Ashwini Rahul; Luo, Yongxiang; Schumacher, Matthias; Nies, Berthold; Lode, Anja; Gelinsky, Michael

    2015-11-01

    Additive manufacturing allows to widely control the geometrical features of implants. Recently, we described the fabrication of calcium phosphate cement (CPC) scaffolds by 3D plotting of a storable CPC paste based on water-immiscible carrier liquid. Plotting and hardening is conducted under mild conditions allowing the (precise and local) integration of biological components. In this study, we have developed a procedure for efficient loading of growth factors in the CPC scaffolds during plotting and demonstrated the feasibility of this approach. Bovine serum albumin (BSA) or vascular endothelial growth factor (VEGF), used as model proteins, were encapsulated in chitosan/dextran sulphate microparticles which could be easily mixed into the CPC paste in freeze-dried state. In order to prevent leaching of the proteins during cement setting, usually carried out by immersion in aqueous solutions, the plotted scaffolds were aged in water-saturated atmosphere (humidity). Setting in humidity avoided early loss of loaded proteins but provided sufficient amount of water to allow cement setting, as indicated by XRD analysis and mechanical testing in comparison to scaffolds set in water. Moreover, humidity-set scaffolds were characterised by altered, even improved properties: no swelling or crack formation was observed and accordingly, surface topography, total porosity and compressive modulus of the humidity-set scaffolds differed from those of the water-set counterparts. Direct cultivation of mesenchymal stem cells on the humidity-set scaffolds over 21days revealed their cytocompatibility. Maintenance of the bioactivity of VEGF during the fabrication procedure was proven in indirect and direct culture experiments with endothelial cells. Additive manufacturing techniques allow the fabrication of implants with defined architecture (inner pore structure and outer shape). Especially printing technologies conducted under mild conditions allow additionally the (spatially controlled

  5. Effects of calcium leaching on diffusion properties of hardened and altered cement pastes

    Science.gov (United States)

    Kurumisawa, Kiyofumi; Haga, Kazuko; Hayashi, Daisuke; Owada, Hitoshi

    2017-06-01

    It is very important to predict alterations in the concrete used for fabricating disposal containers for radioactive waste. Therefore, it is necessary to understand the alteration of cementitious materials caused by calcium leaching when they are in contact with ground water in the long term. To evaluate the long-term transport characteristics of cementitious materials, the microstructural behavior of these materials should be considered. However, many predictive models of transport characteristics focus on the pore structure, while only few such models consider both, the spatial distribution of calcium silicate hydrate (C-S-H), portlandite, and the pore spaces. This study focused on the spatial distribution of these cement phases. The auto-correlation function of each phase of cementitious materials was calculated from two-dimensional backscattered electron imaging, and the three-dimensional spatial image of the cementitious material was produced using these auto-correlation functions. An attempt was made to estimate the diffusion coefficient of chloride from the three-dimensional spatial image. The estimated diffusion coefficient of the altered sample from the three-dimensional spatial image was found to be comparable to the measured value. This demonstrated that it is possible to predict the diffusion coefficient of the altered cement paste by using the proposed model.

  6. Bioactive calcium sulfate/magnesium phosphate cement for bone substitute applications.

    Science.gov (United States)

    Yang, Guangyong; Liu, Jianli; Li, Fan; Pan, Zongyou; Ni, Xiao; Shen, Yue; Xu, Huazi; Huang, Qing

    2014-02-01

    A novel calcium sulfate/magnesium phosphate cement (CSMPC) composite was prepared and studied in the present work. The physical properties including the phases, the microstructures, the setting properties and the compressive strengths of the CSMPCs were studied. The bio-performances of the CSMPCs were comprehensively evaluated using in vitro simulated body fluid (SBF) method and in vitro cell culture. The dependence of the physical and chemical properties of the CSMPC on its composition and microstructure was studied in detail. It is found that the CSMPC composites exhibited mediate setting times (6-12 min) compared to the calcium sulfate (CS) and the magnesium phosphate cement (MPC). They showed an encapsulation structure in which the unconverted hexagonal prism CSH particles were embedded in the xerogel-like MPC matrix. The phase compositions and the mechanical properties of the CSMPCs were closely related to the content of MPC and the hardening process. The CSMPCs exhibited excellent bioactivity and good biocompatibility to support the cells to attach and proliferate on the surface. The CSMPC composite has the potential to serve as bone grafts for the bone regeneration. © 2013.

  7. Bioactive calcium sulfate/magnesium phosphate cement for bone substitute applications

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Guangyong [Department of Orthopaedics, Taizhou Hospital of Zhejiang Province, Linhai Zhejiang, 317000 (China); Department of Orthopaedic Surgery, Second Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, 325000 (China); Liu, Jianli [Trauma Center, Affiliated Hospital of Hainan Medical University, Haikou, Hainan, 570206 (China); Division of Functional Materials and Nanodevices, Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences (CAS), Ningbo, Zhejiang, 315201 (China); Li, Fan; Pan, Zongyou; Ni, Xiao; Shen, Yue [Department of Orthopaedic Surgery, Second Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, 325000 (China); Xu, Huazi, E-mail: spinexu@163.com [Department of Orthopaedic Surgery, Second Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, 325000 (China); Huang, Qing, E-mail: huangqing@nimte.ac.cn [Division of Functional Materials and Nanodevices, Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences (CAS), Ningbo, Zhejiang, 315201 (China)

    2014-02-01

    A novel calcium sulfate/magnesium phosphate cement (CSMPC) composite was prepared and studied in the present work. The physical properties including the phases, the microstructures, the setting properties and the compressive strengths of the CSMPCs were studied. The bio-performances of the CSMPCs were comprehensively evaluated using in vitro simulated body fluid (SBF) method and in vitro cell culture. The dependence of the physical and chemical properties of the CSMPC on its composition and microstructure was studied in detail. It is found that the CSMPC composites exhibited mediate setting times (6–12 min) compared to the calcium sulfate (CS) and the magnesium phosphate cement (MPC). They showed an encapsulation structure in which the unconverted hexagonal prism CSH particles were embedded in the xerogel-like MPC matrix. The phase compositions and the mechanical properties of the CSMPCs were closely related to the content of MPC and the hardening process. The CSMPCs exhibited excellent bioactivity and good biocompatibility to support the cells to attach and proliferate on the surface. The CSMPC composite has the potential to serve as bone grafts for the bone regeneration. - Highlights: • The mechanical strength and degradation rate of CSMPC composites are discussed. • The CSMPC composites exhibited good bioactivity to form bone-like apatite. • The CSMPC composites also show good biocompatibility.

  8. In Vitro Cytotoxicity of Calcium Silicate-Based Endodontic Cement as Root-End Filling Materials

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    Selen Küçükkaya

    2016-01-01

    Full Text Available The aim of this study was to evaluate the cytotoxicity of three types of calcium silicate-based endodontic cement after different incubation periods with human periodontal ligament fibroblasts. Human periodontal ligament fibroblasts were cultured from extracted third molars and seeded in 96-well plates. MTA, calcium enriched mixture (CEM cement, and Biodentine were prepared and added to culture insert plates which were immediately placed into 96-well plates containing cultured cells. After incubation periods of 24, 48, and 72 hours, cell viability was determined with WST-1 assay. Data were analysed statistically by ANOVA with repeated measures and Bonferroni tests. There was no significant difference in cell viability amongst the test materials after each incubation period (P>0.05. MTA and CEM presented more than 90% cell viability after 24 and 48 hours of incubation and showed statistically significant decrease in cell viability after 72 hours of incubation (P<0.05. Biodentine showed significantly less cell viability (73% after 24 hours of incubation, whereas more than 90% cell viability was seen after 48 and 72 hours of incubation (P<0.05. Despite the significant changes in cell viability over time, materials presented similar cytotoxicity profile. Biodentine and CEM can be considered as alternative materials for root-end surgery procedures.

  9. Hydration characteristics and compressive strength of hardened cement pastes containing nano-metakaolin

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    S.M.A. El-Gamal

    2017-04-01

    Full Text Available In this study the effect of inclusion of nano-metakaolin (NMK to ordinary Portland cement (OPC on the hydration characteristics and microstructure of hardened OPC–NMK pastes was studied. The OPC–NMK blends were prepared by the partial substitution of OPC by NMK (4, 6, 10 and 15 weight %. The fresh pastes were made using an initial water/solid (W/S ratio of 0.27 by weight and then hydrated for various time intervals. At the end of each hydration time, the hardened blended cement pastes were tested for compressive strength, free lime content, combined water content, X-ray diffraction (XRD analysis, differential scanning calorimetry (DSC and scanning electron microscopy (SEM. The compressive strength results revealed that the inclusion of nano-metakaolin into OPC improved the mechanical properties of NMK–OPC pastes during almost all ages of hydration, especially with the paste containing 10 wt% NMK. The compressive strength values obtained for OPC paste blended with 4% silica fume (SF and 6% NMK are comparable to those of the neat OPC paste. The DSC thermograms and XRD diffractograms obtained for some selected hardened pastes indicated the formation of amorphous calcium silicate hydrates, calcium sulfoaluminate hydrates, calcium aluminate hydrate and calcium hydroxide. SEM micrographs showed the formation of a dense microstructure for the hardened OPC–NMK and OPC–NMK-SF pastes as compared to the neat OPC paste after 90 days of hydration.

  10. Development of strong and bioactive calcium phosphate cement as a light-cure organic-inorganic hybrid.

    Science.gov (United States)

    Barounian, M; Hesaraki, S; Kazemzadeh, A

    2012-07-01

    In this research, light cured calcium phosphate cements (LCCPCs) were developed by mixing a powder phase (P) consisting of tetracalcium phosphate and dicalcium phosphate and a photo-curable resin phase (L), mixture of hydroxyethylmethacrylate (HEMA)/poly acrylic-maleic acid at various P/L ratios of 2.0, 2.4 and 2.8 g/mL. Mechanical strength, phase composition, chemical groups and microstructure of the cured cements were evaluated at pre-set times, i.e. before and after soaking in simulated body fluid (SBF). The proliferation of Rat-derived osteoblastic cells onto the LCCPCs as well as cytotoxicity of cement extracts were determined by cell counting and 3-{4,5-dimethylthiazol-2yl}-2,5-diphenyl-2H-tetrazolium bromide assay after different culture times. It was estimated from Fourier transforming infrared spectra of cured cements that the setting process is ruled by polymerization of HEMA monomers as well as formation of calcium poly-carboxylate salts. Microstructure of the cured cements consisted of calcium phosphate particles surrounded by polymerized resin phase. Formation of nano-sized needlelike calcium phosphate phase on surfaces of cements with P/L ratios of 2.4 and 2.8 g/mL was confirmed by scanning electron microscope images and X-ray diffractometry (XRD) of the cured specimen soaked in SBF for 21 days. Also, XRD patterns revealed that the formed calcium phosphate layer was apatite phase in a poor crystalline form. Biodegradation of the cements was confirmed by weight loss, change in molecular weight of polymer and morphology of the samples after different soaking periods. The maximum compressive strength of LCCPCs governed by resin polymerization and calcium polycarboxylate salts formation was about 80 MPa for cement with P/L ratio of 2.8 g/mL, after incubation for 24 h. The strength of all cements decreased by decreasing P/L ratio as well as increasing soaking time. The preliminary cell studies revealed that LCCPCs could support proliferation of

  11. Self-Setting Calcium Phosphate Cements with Tunable Antibiotic Release Rates for Advanced Antimicrobial Applications.

    Science.gov (United States)

    Ghosh, Shreya; Wu, Victoria; Pernal, Sebastian; Uskoković, Vuk

    2016-03-01

    Osteomyelitis, an infectious disease predominantly tied to poor sanitary conditions in underdeveloped regions of the world, is in need of inexpensive, easily in situ synthesizable and administrable materials for its treatment. The results of this study stem from the attempt to create one such affordable and minimally invasive therapeutic platform in the form of a self-setting, injectable cement with a tunable drug release profile, composed of only nanoparticulate hydroxyapatite, the synthetic version of the bone mineral. Cements comprised two separately synthesized hydroxyapatite powders, one of which, HAP2, was precipitated abruptly, retaining the amorphous nature longer, and the other one of which, HAP1, was precipitated at a slower rate, more rapidly transitioning to the crystalline structure. Cements were made with four different weight ratios of the two hydroxyapatite components: 100/0, 85/15, 50/50, and 0/100 with respect to HAP1 and HAP2. Both the setting and the release rates measured on two different antibiotics, vancomycin and ciprofloxacin, were controlled using the weight ratio of the two hydroxyapatite components. Various inorganic powder properties were formerly used to control drug release, but here we demonstrate for the first time that the kinetics of the mechanism of formation of a solid compound can be controlled to produce tunable drug release profiles. Specifically, it was found that the longer the precursor calcium phosphate component of the cement retains the amorphous nature of the primary precipitate, the more active it was in terms of speeding up the diffusional release of the adsorbed drug. The setting rate was, in contrast, inversely proportional to the release rate and to the content of this active hydroxyapatite component, HAP2. The empirical release profiles were fitted to a set of equations that could be used to tune the release rate to the therapeutic occasion. All of the cements loaded with vancomycin or ciprofloxacin inhibited the

  12. Biocompatibility and setting time of CPM-MTA and white Portland cement clinker with or without calcium sulfate

    Directory of Open Access Journals (Sweden)

    Clovis Monteiro BRAMANTE

    2013-01-01

    Full Text Available Objective To evaluate the biocompatibility and the setting time of Portland cement clinker with or without 2% or 5% calcium sulfate and MTA-CPM. Material and Methods Twenty-four mice (Rattus norvegicus received subcutaneously polyethylene tubes filled with Portland cement clinker with or without 2% or 5% calcium sulfate and MTA. After 15, 30 and 60 days of implantation, the animals were killed and specimens were prepared for microscopic analysis. For evaluation of the setting time, each material was analyzed using Gilmore needles weighing 113.5 g and 456.5 g, according to the ASTM specification Number C266-08 guideline. Data were analyzed by ANOVA and Tukey's test for setting time and Kruskal-Wallis and Dunn test for biocompatibility at 5% significance level. Results Histologic observation showed no statistically significant difference of biocompatibility (p>0.05 among the materials in the subcutaneous tissues. For the setting time, clinker without calcium sulfate showed the shortest initial and final setting times (6.18 s/21.48 s, followed by clinker with 2% calcium sulfate (9.22 s/25.33 s, clinker with 5% calcium sulfate (10.06 s/42.46 s and MTA (15.01 s/42.46 s. Conclusions All the tested materials showed biocompatibility and the calcium sulfate absence shortened the initial and final setting times of the white Portland cement clinker.

  13. Porous poly(DL-lactic-co-glycolic acid)/calcium phosphate cement composite for reconstruction of bone defects.

    NARCIS (Netherlands)

    Ruhe, P.Q.; Hedberg, E.L.; Padron, N.T.; Spauwen, P.H.M.; Jansen, J.A.; Mikos, A.G.

    2006-01-01

    Calcium phosphate (Ca-P) cements are injectable, self-setting ceramic pastes generally known for their favorable bone response. Ingrowth of bone and subsequent degradation rates can be enhanced by the inclusion of macropores. Initial porosity can be induced by CO(2) foaming during setting of the

  14. Halting of the calcium aluminate cement hydration process; Interrupcao do processo de hidratatacao de um cimento de aluminato de calcio

    Energy Technology Data Exchange (ETDEWEB)

    Luz, A.P.; Borba, N.Z; Pandolfelli, V.C., E-mail: anapaula.light@gmail.com, E-mail: vicpando@power.ufscar.br [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia de Materiais

    2011-07-01

    The calcium aluminate cement reactions with water lead to the anhydrous phases dissolution resulting a saturated solution, followed by nucleation and crystal growth of the hydrate compounds. This is a dynamic process, therefore, it is necessary to use suitable methods to halt the hydration in order to study the phase transformations kinetics of such materials. In this work two methods are evaluated: use of acetone and microwave drying, aiming to withdraw the free water and inhibit further reactions. X ray diffraction and thermogravimetric tests were used to quantify the phases generated in the cement samples which were kept at 37 deg C for 1 to 15 days. The advantages and disadvantages of those procedures are presented and discussed. The use of microwave to halt the hydration process seems to be effective to withdraw the cement free water, and it can further be used in researches of the refractory castables area, endodontic cements, etc. (author)

  15. Calcium phosphate cements properties with polymers addition; Propriedades do cimento de fosfato de calcio com adicao de polimeros

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, J.M.; Trajano, W.T.; Escobar, C.F.; Santos, L.A., E-mail: julianafernandes2@yahoo.com.br [Universidade Federal do Rio Grande do Sul (UFRGS), RS (Brazil)

    2012-07-01

    Calcium phosphate cements (CPC) have attracted great interest to use in orthopedics and dentistry as replacements for damaged parts of the skeletal system, showing good biocompatibility and osseointegration, allowing its use as bone graft. Several studies have shown that the addition of polymer additives have a strong influence on the cement properties. The low mechanical strength is the main obstacle to greater use of CPC as an implant material. The objective of this study was to evaluate properties of a cement based on α-tricalcium phosphate (α-TCP), added polymers. PVA (10%, 8%, 6%), sodium alginate (2%) and polyacrylate ammonia (3%), all in weight, were added to the synthesized α-TCP powder. The samples were molded and evaluated for density, porosity in vitro test (Simulated Body Fluid), crystalline phases and mechanical strength. The results show increased the mechanical properties of the cement when added these polymers.

  16. Augmentation of pedicle screw fixation strength using an injectable calcium phosphate cement as a function of injection timing and method.

    Science.gov (United States)

    Renner, Susan M; Lim, Tae-Hong; Kim, Whoan-Jeang; Katolik, Leonid; An, Howard S; Andersson, Gunnar B J

    2004-06-01

    Axial pullout tests using fresh cadaveric thoracolumbar vertebral bodies. To evaluate the effect of a new injectable calcium phosphate cement on the axial pullout strength of both revised and augmented pedicle screws in comparison with polymethyl methacrylate and in terms of injection method. Failure of pedicle screws by loosening and back out remains a significant clinical problem and is of particular concern for patients with low bone quality. Polymethyl methacrylate was shown to significantly improve the screw pullout strength. However, polymethyl methacrylate is known to have a high polymerization temperature, which may damage surrounding tissues, and a short handling time, and it lacks long-term biocompatibility. Bone mineral cements such as calcium phosphate have a longer working time, very low thermal effect, and are biodegradable as well as having good mechanical strength. Recently, new calcium phosphate cement with improved infiltration properties for better injectability has been introduced, but its performance in augmenting the pedicle screw fixation has not been tested yet. The bone mineral densities of 52 vertebral bodies (T11-L5) were measured using dual-energy x-ray absorptiometry. In each vertebral body, a 6.5-mm-diameter and 45 +/- 5-mm-long pedicle screw was inserted into either the right or left pedicle, representing an initial intact implantation. These intact screws were pulled axially until failure at 10 mm/min. Following failure of the intact pedicle, 3.0 cc of cement was injected into the failed screw hole, representing a revision case, and the prepared screw hole in the contralateral intact pedicle representing an augmentation case. The cement was injected either to the distal tip of the screw hole (calcium phosphate-1 group, n = 19) or along the entire length of the screw hole (calcium phosphate-2 group, n = 20), and the screws were inserted. The cement was then allowed to cure for 24 hours at room temperature before both screws were

  17. Influence of portland cement replacement in high calcium fly ash geopolymer paste

    Directory of Open Access Journals (Sweden)

    Tanakorn Phoo-ngernkham

    2014-03-01

    Full Text Available This article presents the influence of ordinary Portland cement (OPC replacement in high calcium fly ash (FA geopolymer paste. FA was used to replace OPC at the rate of 5, 10 and 15% by mass of binder. Sodium silicate (Na2SiO3 and 10 molar sodium hydroxide (NaOH solutions were used as the alkaline solution in the reaction. The Na2SiO3/NaOH ratio of 2.0 and the liquid/binder (L/B ratio of 0.60 were used in all mixtures. The results of increase OPC replacement, the setting time and compressive strain capacity decreased while the compressive strength and modulus of elasticity increased. The compressive strength and modulus of elasticity at 28 days of geopolymer pastes with 15% OPC replacement were 36.7 MPa and 13,300 MPa, respectively.

  18. Indirect pulp therapy in a symptomatic mature molar using calcium enriched mixture cement.

    Science.gov (United States)

    Torabzadeh, Hassan; Asgary, Saeed

    2013-01-01

    Dental pulp has the ability of repair/regeneration. Indirect pulp therapy (IPT) is recommended for pulp preservation in asymptomatic teeth with extremely deep caries as well as teeth with clinical symptoms of reversible pulpitis. In this case study, we performed IPT with calcium enriched mixture (CEM) cement on a symptomatic permanent molar. After clinical/radiographic examinations the tooth was diagnosed with irreversible pulpitis and associated apical periodontitis. IPT involved partial caries removal, the placement of CEM cement pulp cap and overlying adhesive permanent restoration. At the 1 week follow-up, patient's spontaneous symptoms had resolved. One-year follow-up demonstrated pulp vitality, clinical function, as well as the absence of pain/tenderness to percussion/palpation/cold sensitivity tests; periapical radiograph showed a healing periradicular lesion with newly formed bone, that is normal pulp with normal periodontium. These favorable results indicate that IPT/CEM may be a good treatment option in comparison to endodontic treatment in young patients. IPT of deep-caries lesion is an easier, more practical and valuable treatment plan than complete caries removal.

  19. Microleakage of glass-ionomer cement placed in association with non-setting calcium hydroxide.

    Science.gov (United States)

    Mahmood, S A; Wood, D J; Boyle, E L; Jarad, F D; Youngson, C C

    2005-05-01

    The purpose of this investigation was to determine whether non-setting calcium hydroxide [Ca (OH)2] cement placed in the root canal system of premolar teeth would affect the subsequent microleakage of a glass-ionomer restoration (GIC). Following selection, 62 human premolar teeth extracted for orthodontic reasons were accessed and root canals prepared according to a standardized procedure. The specimens were then allocated randomly into two major groups each of 30 teeth. Two other teeth were used as a positive and a negative control. The control group was restored with glass-ionomer cement following drying of the canal and placement of a cotton wool pledget. The test group had all canals dressed with non-setting Ca(OH)2 and then was subdivided, one set (n = 22) being restored following conditioning of the access cavity margins, the other (n = 8) having the margins cleaned with a hand excavator. Samples were assessed for microleakage using a two-point scoring system (leakage or no leakage) in conjunction with a clearing technique using AgNO3. Using Fisher's exact test, a statistically significant difference was found between the control and test groups (P < 0.05) but there was no significant difference between the excavated and conditioned cavities (P=0.55). It is concluded that contamination of access cavity margins with Ca(OH)2 during medication of a root canal interferes with the bond of GIC, resulting in increased microleakage in vitro.

  20. Hydrate Phase Assemblages in Calcium Sulfoaluminate - Metakaolin - Limestone Blends

    DEFF Research Database (Denmark)

    Pedersen, Malene Thostrup; Lothenbach, Barbara; Winnefeld, Frank

    2017-01-01

    as 27Al and 29Si NMR and compared with predictions from thermodynamic modelling. The results show almost full degrees of reaction for ye’elimite in all blends and that the degrees of reaction for belite and MK have an important impact on the hydrate phases and their quantities formed in the ternary...... systems....

  1. Porous calcium phosphate-poly (lactic-co-glycolic) acid composite bone cement: A viable tunable drug delivery system.

    Science.gov (United States)

    Roy, Abhijit; Jhunjhunwala, Siddharth; Bayer, Emily; Fedorchak, Morgan; Little, Steve R; Kumta, Prashant N

    2016-02-01

    Calcium phosphate based cements (CPCs) are frequently used as bone void fillers for non-load bearing segmental bone defects due to their clinically relevant handling characteristics and ability to promote natural bone growth. Macroporous CPC scaffolds with interconnected pores are preferred for their ability to degrade faster and enable accelerated bone regeneration. Herein, a composite CPC scaffold is developed using newly developed resorbable calcium phosphate cement (ReCaPP) formulation containing degradable microspheres of bio-compatible poly (lactic-co-glycolic acid) (PLGA) serving as porogen. The present study is aimed at characterizing the effect of in-vitro degradation of PLGA microspheres on the physical, chemical and structural characteristics of the composite cements. The porosity measurements results reveal the formation of highly interconnected macroporous scaffolds after degradation of PLGA microspheres. The in-vitro characterizations also suggest that the degradation by products of PLGA reduces the pH of the local environment thereby increasing the dissolution rate of the cement. In addition, the in-vitro vancomycin release from the composite CPC scaffold suggests that the drug association with the composite scaffolds can be tuned to achieve control release kinetics. Further, the study demonstrates control release lasting for longer than 10weeks from the composite cements in which vancomycin is encapsulated in PLGA microspheres. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Cementing Material From Rice Husk-Broken Bricks-Spent Bleaching Earth-Dried Calcium Carbide Residue

    Directory of Open Access Journals (Sweden)

    Muthengia Jackson Washira

    2012-10-01

    Full Text Available A cementious material, coded CSBR (Carbide residue Spent bleaching earth Broken bricks and Rice husks, was made from dried calcium carbide residue (DCCR and an incinerated mix of rice husks (RH, broken bricks (BB and spent bleaching earth (SBE. Another material, coded SBR (Spent bleaching earth Broken bricks and Rice husk ash, was made from mixing separately incinerated RH, SBE and ground BB in the same ash ratio as in CSBR. When CSBR was inter-ground with Ordinary Portland Cement (OPC, it showed a continued decrease in Ca(OH2 in the hydrating cement as a function of curing time and replacement levels of the cement. Up to 45 % replacement of the OPC by CSBR produced a Portland pozzolana cement (PPC material that passed the relevant Kenyan Standard. Incorporation of the CSBR in OPC reduces the resultant calcium hydroxide from hydrating Portland cement. The use of the waste materials in production of cementitious material would rid the environment of wastes and lead to production of low cost cementitious material.

  3. Synthesis and mechanical properties of a calcium sulphoaluminate cement made of industrial wastes

    Directory of Open Access Journals (Sweden)

    Gallardo, M.

    2014-09-01

    Full Text Available Environmentally-friendly calcium sulphoaluminate clinkers were obtained from a mixture of aluminium dross, fluorgypsum, fly ash and CaCO₃ at temperatures within the range of 1100 to 1400 °C. After the heat treatments Ca₄Al₆O₁₂SO₄ was the main phase. Three different cements were prepared using the clinkers synthesized at 1250, 1350 and 1400 °C; the clinker powders were mixed with 20 wt% of hemihydrate. Cement pastes were prepared using a water/cement ratio (w/c, 0.4 followed by curing at 20 or 40 °C for periods of time ranging from 1 to 28 days. Most of the samples showed high compression strengths 40–47 MPa after 28 days, which were comparable to the strength of Portland cement. Ettringite was the main hydration product and its morphology consisted of acicular and hexagonal plates, which is typical of this phase.Se fabricaron clinkers de bajo impacto ambiental a base de sulfoaluminato de calcio calcinando mezclas de escoria de aluminio, fluoryeso, ceniza volante y CaCO₃ a diferentes temperaturas dentro de un rango de 1100 a 1400 °C. Se observó la formación de Ca₄Al₆O₁₂SO₄ como fase principal. Para obtener los cementos, los clinkers obtenidos a 1250, 1350 y 1400 °C se mezclaron con 20% en peso de hemihidrato. Se prepararon pastas usando una relación agua/cemento, de 0.4 y se curaron a 20 y 40 °C por diferentes periodos de tiempo desde 1 hasta 28 días. Los valores de resistencia a la compresión a los 28 días de curado de la mayoría de las muestras estuvieron entre 40–47 MPa, equiparables a los de referencia de pastas de cemento Portland. La etringita fue el principal producto de hidratación y su morfología consistió de placas hexagonales y aciculares, típicas de esta fase.

  4. Nanostructural Deformation Analysis of Calcium Silicate Hydrate in Portland Cement Paste by Atomic Pair Distribution Function

    Directory of Open Access Journals (Sweden)

    Hiroshi Suzuki

    2016-01-01

    Full Text Available The deformation of nanostructure of calcium silicate hydrate (C-S-H in Portland cement (PC paste under compression was characterized by the atomic pair distribution function (PDF, measured using synchrotron X-ray diffraction. The PDF of the PC paste exhibited a unique deformation behavior for a short-range order below 2.0 nm, close to the size of the C-S-H globule, while the deformation for a long-range order was similar to that of a calcium hydroxide phase measured by Bragg peak shift. The compressive deformation of the C-S-H nanostructure was comprised of three stages with different interactions between globules. This behavior would originate from the granular nature of C-S-H, which deforms with increasing packing density by slipping the interfaces between globules, rearranging the overall C-S-H nanostructure. This new approach will lead to increasing applications of the PDF technique to understand the deformation mechanism of C-S-H in PC-based materials.

  5. Effect of Poly(Vinyl Alcohol) Addition on the Properties of Hydrothermal Derived Calcium Phosphate Cement for Bone Filling Materials

    Science.gov (United States)

    Razali, N. N.; Sopyan, I.; Mel, M.; Salleh, H. M.; Rahman, M. M.; Singh, R.

    2017-06-01

    The effect of addition of poly(vinyl alcohol) on hydrothermal derived calcium phosphate cement has been studied. The precursors used to prepare the cement were calcium oxide (CaO) and ammonium dihydrogen phosphate (NH4H2PO4); the reaction was conducted in water at 80-100°C. To improve properties of CPC, poly(vinyl alcohol) (PVA) of 1wt% and 2wt% was added to the liquid phase of CPC and the results were compared to CPC without PVA addition. The addition of PVA was proved to bring remarkable effects on cohesion, setting time and mechanical strength of CPC which make it suitable physically for injectable bone filler applications.

  6. Calcium phosphate cement as a "barrier-graft" for the treatment of human periodontal intraosseous defects

    Directory of Open Access Journals (Sweden)

    Rajesh J

    2009-01-01

    Full Text Available Background : Calcium phosphate cements (CPC are apparently good candidates for periodontal treatment by virtue of their biocompatibility, mouldability and osteoconductivity. However, the clinical efficacy in this regard has not been established. This study is aimed at the evaluation of the efficacy of a formulation of CPC in healing human periodontal intraosseous defects in comparison with hydroxyapatite ceramic granules. Materials and Methods : In this clinical study, 60 patients with periodontal defects were divided into 2 test groups and 1 control group. The defect sites in the test groups were repaired with CPC and hydroxyapatite ceramic granules (HAG. Debridement alone was given in the control group. The progress was assessed at 3, 6, 9 and 12 months observation intervals through soft tissue parameters (probing depth, attachment level and gingival recession. Results: CPC showed significantly better outcome. Probing depth reduction values of CPC, HAG and Control at 6 months were 5.40 ± 1.43, 3.75 ± 1.71 and 2.90 ± 1.48, and those at 12 months were 6.20 ± 1.80, 4.5 ± 1.91 and 2.95 ± 1.73. Clinical attachment gain values of CPC, HAG and Control at 6 months were 5.15 ± 1.50, 3.45 ± 1.96 and 2.25 ± 1.52, and those at 12 months were 5.80 ± 2.02, 3.55 ± 2.06 and 2.30 ± 1.78, In both cases the P value was < 0.001 showing high significance. The gingival recession over 12 months, for the CPC group is lesser than that in the HAG group and the value for the control group is marginally higher than both. Soft-tissue measurements were appended by postoperative radiographs and surgical re-entry in selected cases. Conclusions: Calcium phosphate cement is found to be significantly better than hydroxyapatite ceramic granules. The material could be considered as a "barrier-graft".

  7. Intrinsic differences in atomic ordering of calcium (alumino)silicate hydrates in conventional and alkali-activated cements

    Energy Technology Data Exchange (ETDEWEB)

    White, Claire E., E-mail: whitece@princeton.edu [Department of Civil and Environmental Engineering, Princeton University, Princeton (United States); Andlinger Center for Energy and the Environment, Princeton University, Princeton (United States); Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos (United States); Physics and Chemistry of Materials, Los Alamos National Laboratory, Los Alamos (United States); Daemen, Luke L.; Hartl, Monika; Page, Katharine [Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos (United States)

    2015-01-15

    The atomic structures of calcium silicate hydrate (C–S–H) and calcium (–sodium) aluminosilicate hydrate (C–(N)–A–S–H) gels, and their presence in conventional and blended cement systems, have been the topic of significant debate over recent decades. Previous investigations have revealed that synthetic C–S–H gel is nanocrystalline and due to the chemical similarities between ordinary Portland cement (OPC)-based systems and low-CO{sub 2} alkali-activated slags, researchers have inferred that the atomic ordering in alkali-activated slag is the same as in OPC–slag cements. Here, X-ray total scattering is used to determine the local bonding environment and nanostructure of C(–A)–S–H gels present in hydrated tricalcium silicate (C{sub 3}S), blended C{sub 3}S–slag and alkali-activated slag, revealing the large intrinsic differences in the extent of nanoscale ordering between C–S–H derived from C{sub 3}S and alkali-activated slag systems, which may have a significant influence on thermodynamic stability, and material properties at higher length scales, including long term durability of alkali-activated cements.

  8. Cementing Material From Rice Husk-Broken Bricks-Spent Bleaching Earth-Dried Calcium Carbide Residue

    OpenAIRE

    Muthengia Jackson Washira

    2012-01-01

    A cementious material, coded CSBR (Carbide residue Spent bleaching earth Broken bricks and Rice husks), was made from dried calcium carbide residue (DCCR) and an incinerated mix of rice husks (RH), broken bricks (BB) and spent bleaching earth (SBE). Another material, coded SBR (Spent bleaching earth Broken bricks and Rice husk ash), was made from mixing separately incinerated RH, SBE and ground BB in the same ash ratio as in CSBR. When CSBR was inter-ground with Ordinary Portland Cement (OPC)...

  9. Effect of polydopamine on the biomimetic mineralization of mussel-inspired calcium phosphate cement in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zongguang [Key Lab of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Qu, Shuxin, E-mail: qushuxin@swjtu.edu.cn [Key Lab of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Zheng, Xiaotong; Xiong, Xiong [Key Lab of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Fu, Rong; Tang, Kuangyun; Zhong, Zhendong [Department of Plastic Surgery, Academy of Medical Sciences and Sichuan Provincial People' s Hospital, Chengdu 610041 (China); Weng, Jie [Key Lab of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China)

    2014-11-01

    Inspired by the excellent adhesive property of mussel adhesive protein, we added polydopamine (PDA) to calcium phosphate cement (PDA–CPC) to enhance its compressive strength previously. The mineralization and mechanism on PDA–CPC were investigated by soaking it in simulated body fluid in this study. The results indicated that PDA promoted the conversion of dicalcium phosphate dihydrate and α-tricalcium phosphate to hydroxyapatite (HA) in the early stage but inhibited this conversion subsequently. PDA promoted the rapid mineralization on PDA–CPC to form a layer of nanoscale calcium phosphate (CaP) whereas there was no CaP formation on the control-CPC after 1 d of soaking. This layer of nanoscale CaP was similar to that of natural bone, which was always observed during soaking. X-ray photoelectron spectroscopy showed that the peak of C=O of PDA existed in the newly formed CaP on PDA–CPC, indicating the co-precipitation of CaP with PDA. Furthermore, the newly formed CaP on PDA–CPC was HA confirmed by transmission electron microscopy, which the newly formed HA was in association with PDA. Therefore, PDA increased the capacity of mineralization of CPC and induced the formation of nanoscale bone-like apatite on PDA–CPC. Thus, this provides the feasible route for surface modification on CPC. - Highlights: • Effect of polydopamine (PDA) on the in vitro mineralization of PDA-CPC was studied. • PDA promoted the rapid mineralization on PDA-CPC to form a nanoscale HA layer. • The precipitation of the nanoscale HA layer on PDA-CPC accompanied with PDA. • Polydopamine induced mineralization is feasible for surface modification of CaP.

  10. Synthesis of Ag doped calcium phosphate particles and their antibacterial effect as additives in dental glass ionomer cements.

    Science.gov (United States)

    Chen, Song; Gururaj, Satwik; Xia, Wei; Engqvist, Håkan

    2016-11-01

    Developing dental restorations with enhanced antibacterial properties has been a constant quest for materials scientists. The aim of this study was to synthesize silver doped calcium phosphate particles and use them to improve antibacterial properties of conventional glass ionomer cement. The Ag doped monetite (Ag-DCPA) and hydroxyapatite (Ag-HA) were synthesized by precipitation method and characterized using X-ray diffraction, scanning electron microscope and X-ray fluorescence spectroscopy. The antibacterial properties of the cements aged for 1 day and 7 days were evaluated by direct contact measurement using staphylococcus epidermis Xen 43. Ion concentrations (F- and Ag+) and pH were measured to correlate to the results of the antibacterial study. The compressive strength of the cements was evaluated with a crosshead speed of 1 mm/min. The glass ionomer cements containing silver doped hydroxyapatite or monetite showed improved antibacterial properties. Addition of silver doped hydroxyapatite or monetite did not change the pH and ion release of F-. Concentration of Ag+ was under the detection limit (0.001 mg/L) for all samples. Silver doped hydroxyapatite or monetite had no effect on the compressive strength of glass ionomer cement.

  11. CT volumetry of intravertebral cement after kyphoplasty. Comparison of polymethylmethacrylate and calcium phosphate in a 12-month follow-up

    Energy Technology Data Exchange (ETDEWEB)

    Libicher, M.; Noeldge, G.; Kauffmann, G.W. [University of Heidelberg, Department of Diagnostic Radiology, Heidelberg (Germany); Vetter, M.; Wolf, I.; Meinzer, H.P. [Deutsches Krebsforschungszentrum, Departments of Medical and Biological Informatics, Heidelberg (Germany); Kasperk, C.; Grafe, I. [University of Heidelberg, Department of Internal Medicine, Heidelberg (Germany); Fonseca, K.D.; Meeder, P.J. [University of Heidelberg, Department of Trauma Surgery, Heidelberg (Germany); Hillmeier, J. [St. Vincenz Hospital, Department of Trauma Surgery, Limburg (Germany)

    2005-08-01

    This study was intended to measure the volume of intravertebral cement after balloon kyphoplasty with high resolution computed tomography (CT) and dedicated software. Volume changes of biocompatible calcium phosphate cement (CPC) were detected during a follow-up of 12 months. Measurements were compared with a control group of patients treated with polymethylmethacrylate (PMMA). Twenty-three vertebrae (14 CPC, 9 PMMA) of 12 patients were examined with CT using an identical imaging protocol. Dedicated software was used to quantify intravertebral cement volume in subvoxel resolution by analyzing each cement implant with a density-weighted algorithm. The mean volume reduction of CPC was 0.08 ml after 12 months, which corresponds to an absorption rate of 2 vol%. However, the difference did not reach significance level (P>0.05). The mean error estimate was 0.005 ml, indicating excellent precision of the method. CT volumetry appears a precise tool for measurement of intravertebral cement volume. CT volumetry offers the possibility of in vivo measurement of CPC resorption. (orig.)

  12. Evaluation of the biphasic calcium composite (BCC), a novel bone cement, in a minipig model of pulmonary embolism.

    Science.gov (United States)

    Qin, Yi; Ye, Jichao; Wang, Peng; Gao, Liangbin; Jiang, Jianming; Wang, Suwei; Shen, Huiyong

    2016-01-01

    Polymethylmethacrylate (PMMA) bone cement, which is used as a filler material in vertebroplasty, is one of the major sources of pulmonary embolism in patients who have undergone vertebroplasty. In the present study, we established and evaluated two animal models of pulmonary embolism by injecting PMMA or biphasic calcium composite (BCC) bone cement with a negative surface charge. A total of 12 adults and healthy Wuzhishan minipigs were randomly divided into two groups, the PMMA and BBC groups, which received injection of PMMA bone cement and BBC bone cement with a negative surface charge in the circulation system through the pulmonary trunk, respectively, to construct animal models of pulmonary embolism. The hemodynamics, arterial blood gas, and plasma coagulation were compared between these two groups. In addition, morphological changes of the lung were examined using three-dimensional computed tomography. The results showed that both PMMA and BCC injections induced pulmonary embolisms in minipigs. Compared to the PMMA group, the BCC group exhibited significantly lower levels of arterial pressure, pulmonary artery pressure, blood oxygen pressure, blood carbon dioxide pressure, blood bicarbonate, base excess, antithrombin III and D-dimer. In conclusion, BCC bone cement with a negative surface charge is a promising filler material for vertebroplasty.

  13. Stimulation of Odontogenesis and Angiogenesis via Bioactive Nanocomposite Calcium Phosphate Cements Through Integrin and VEGF Signaling Pathways.

    Science.gov (United States)

    Lee, Sang-Im; Lee, Eui-Suk; El-Fiqi, Ahmed; Lee, So-Youn; Eun-Cheol Kim; Kim, Hae-Won

    2016-05-01

    Formulating self-setting calcium phosphate cements (CPCs) with secondary phases particularly in the nanoscale order holds great promise to improve biological properties. Here, we focus on the effect that bioactive glass nanoparticles (BGN) incorporated in CPC compositions can have on the proliferation, odontogenic differentiation, and angiogenic stimulation of stem cells derived from human dental pulp (HDPSCs). These odontogenic and angiogenic events are of special importance in the dentin-pulp regeneration processes. In comparison to pure CPCs, nanocomposite cements exhibit a significantly improved proliferation of HDPSCs, and the improvement is more significant as the BGN content increases. The nanocomposite cements substantially enhance the adhesion of cells, and significantly up-regulate odontogenic differentiation, including alkaline phosphatase (ALP) activity and the expressions of odontogenic genes (sialophosphoprotein, dentin matrix protein I, ALP, osteopontin and osteocalcin). Furthermore, the use of nanocomposite cements result in stimulation of angiogenic gene expression (VEGF, FGF-2, VEGFRs, PECAM-1, and VE-cadherin) and protein production (VEGF, VEGFR-1). The angiogenic stimulation by the HDPSCs significantly affects the endothelial cell behaviors, that is, the endothelial cell migration and the tubular network formation are substantially improved when treated with HDPSC-conditioned medium, particularly with the help of nanocomposite cements. The integrin and VEGF signaling pathways are reasoned for the stimulation of the odontogenesis and angiogenesis of cells, where the nanocomposite cements up-regulate the integrin subsets α1, α2, α3, and β1, and activate the integrin downstream signal pathways, such as p-FAK, p-Akt, p-paxillin, JNK, EK, and NF-κB, as well as other nuclear transcriptional factors, including CREB, STAT-3, and ELK-1. The current results indicate that the new formulation of the nanocomposite self-setting cements might provide some

  14. Modifications of a calcium phosphate cement with biomolecules--influence on nanostructure, material, and biological properties.

    Science.gov (United States)

    Vater, Corina; Lode, Anja; Bernhardt, Anne; Reinstorf, Antje; Nies, Berthold; Gelinsky, Michael

    2010-12-01

    Calcium phosphate cements (CPC), forming hydroxyapatite during the setting reaction, are characterized by good biocompatibility and osteoconductivity, however, their remodeling into native bone tissue is slow. One strategy to improve remodeling and bone regeneration is the directed modification of their nanostructure. In this study, a CPC was set in the presence of cocarboxylase, glucuronic acid, tartaric acid, α-glucose-1-phosphate, L-arginine, L-aspartic acid, and L-lysine, respectively, with the aim to influence formation and growth of hydroxyapatite crystals through the functional groups of these biomolecules. Except for glucuronic acid, all these modifications resulted in the formation of smaller and more agglomerated hydroxyapatite particles which had a positive impact on the biological performance indicated by first experiments with the human osteoblast cell line hFOB 1.19. Moreover, adhesion, proliferation, and osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSC) as well as binding of the growth factors BMP-2 and VEGF was investigated on CPC modified with cocarboxylase, arginine, and aspartic acid. Initial adhesion of hBMSC was improved on these three modifications and proliferation was enhanced on CPC modified with cocarboxylase and arginine whereas osteogenic differentiation remained unaffected. Modification of the CPC with arginine and aspartic acid, but not with cocarboxylase, led to a higher BMP-2 binding. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.

  15. Bi-layered calcium phosphate cement-based composite scaffold mimicking natural bone structure

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    Fupo He and Jiandong Ye

    2013-01-01

    Full Text Available In this study, a core/shell bi-layered calcium phosphate cement (CPC-based composite scaffold with adjustable compressive strength, which mimicked the structure of natural cortical/cancellous bone, was fabricated. The dense tubular CPC shell was prepared by isostatic pressing CPC powder with a specially designed mould. A porous CPC core with unidirectional lamellar pore structure was fabricated inside the cavity of dense tubular CPC shell by unidirectional freeze casting, followed by infiltration of poly(lactic-co-glycolic acid and immobilization of collagen. The compressive strength of bi-layered CPC-based composite scaffold can be controlled by varying thickness ratio of dense layer to porous layer. Compared to the scaffold without dense shell, the pore interconnection of bi-layered scaffold was not obviously compromised because of its high unidirectional interconnectivity but poor three dimensional interconnectivity. The in vitro results showed that the rat bone marrow stromal cells attached and proliferated well on the bi-layered CPC-based composite scaffold. This novel bi-layered CPC-based composite scaffold is promising for bone repair.

  16. In vitro bioactivity and biocompatibility of calcium phosphate cements using Hydroxy-propyl-methyl-Cellulose (HPMC)

    Science.gov (United States)

    Jyoti, M. Anirban; Thai, Van Viet; Min, Young Ki; Lee, Byong-Taek; Song, Ho-Yeon

    2010-12-01

    In this study, the bioactivity and biocompatibility of new calcium phosphate bone cements (CPC) using Hydroxy-propyl-methyl-Cellulose (HPMC) was evaluated to understand the effect of HPMC on bone-bonding apatite formation and biocompatibility. In vitro bioactivity was investigated by incubating the CPC samples containing different ratios of HPMC (0%, 2% and 4% HPMC) in simulated body fluid (SBF) for 2, 7, 14 and 28 days. The formation of bone like apatite was confirmed on CPC surfaces by SEM and XRD analysis. Higher HPMC content of CPC showed faster apatite deposition in SBF. A high Ca ion dissolution profile was also reported with an increase of pH in all samples in SBF. The apatite formation ability of these CPC samples was found to be dependent on both surface chemistry and immersion time in SBF. The In vitro cytotoxicity test showed that the CPC samples with 4% HPMC were fairly cytocompatible for fibroblast L-929 cells. SEM images showed that MG-63 cells were successfully attached to the CPC samples and well proliferated.

  17. Properties of high calcium fly ash geopolymer pastes with Portland cement as an additive

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    Phoo-ngernkham, Tanakorn; Chindaprasirt, Prinya; Sata, Vanchai; Pangdaeng, Saengsuree; Sinsiri, Theerawat

    2013-02-01

    The effect of Portland cement (OPC) addition on the properties of high calcium fly ash geopolymer pastes was investigated in the paper. OPC partially replaced fly ash (FA) at the dosages of 0, 5%, 10%, and 15% by mass of binder. Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solutions were used as the liquid portion in the mixture: NaOH 10 mol/L, Na2SiO3/NaOH with a mass ratio of 2.0, and alkaline liquid/binder (L/B) with a mass ratio of 0.6. The curing at 60°C for 24 h was used to accelerate the geopolymerization. The setting time of all fresh pastes, porosity, and compressive strength of the pastes at the stages of 1, 7, 28, and 90 d were tested. The elastic modulus and strain capacity of the pastes at the stage of 7 d were determined. It is revealed that the use of OPC as an additive to replace part of FA results in the decreases in the setting time, porosity, and strain capacity of the paste specimens, while the compressive strength and elastic modulus seem to increase.

  18. In vitro comparison of elution characteristics of vancomycin from calcium phosphate cement and polymethylmethacrylate.

    Science.gov (United States)

    Urabe, Ken; Naruse, Kouji; Hattori, Hideki; Hirano, Masahiro; Uchida, Kentaroo; Onuma, Kenji; Park, Hwang Jung; Itoman, Moritoshi

    2009-11-01

    Calcium phosphate cement [CPC (Biopex)] has been used as the drug delivery system of choice for treatment of infected joint replacement because of its good elution efficiency. The influence of CPC polymerization on the bactericidal activity of vancomycin (VCM) impregnated into CPC has not been investigated. We compared VCM concentration, bactericidal activity, and profile of eluates between CPC and polymethylmethacrylate (PMMA; Cemex RX). Test specimens consisted of a powder composite of CPC or PMMA, VCM and solvent (10:0.25:3.3 g). Each test specimen was immersed in sterile phosphate-buffered saline. Eluates obtained on days 1, 3, 7, and 14 and weeks 4, 8, and 12 were evaluated by high performance liquid chromatography (HPLC) and by microbiological assay (MBA). The elution level of VCM from CPC/VCM on day 1 was 8.1 fold greater than that from PMMA/VCM. The detection periods of VCM from CPC/VCM and PMMA/VCM were 8 weeks and 14 days, respectively. The values of eluates from CPC/VCM and PMMA/VCM obtained by HPLC were comparable to those obtained by MBA. HPLC chromatogram showed that the elution profiles of VCM from CPC/VCM and PMMA/VCM on day 1 were very close to those of standard solutions. CPC could release more VCM over a longer period than PMMA. The polymerization of CPC and PMMA did not alter the inhibitory activity of VCM and did not denature VCM.

  19. Tooth Discoloration Induced by Different Calcium Silicate-based Cements: A Systematic Review of In Vitro Studies.

    Science.gov (United States)

    Możyńska, Joanna; Metlerski, Marcin; Lipski, Mariusz; Nowicka, Alicja

    2017-10-01

    On the basis of many clinical observations, some calcium silicate-based cements have a high potential for staining tooth tissue. This feature greatly limits the use of those cements, particularly for anterior teeth. This review aimed to provide a systematic evaluation of published in vitro studies to determine the effect of different calcium silicate-based cements on dental tissue discoloration. This literature review was developed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. The literature search was based on all publications without a year limit. The last search was performed on October 22, 2016. An electronic search was performed on MEDLINE (PubMed), Cochrane, and Scopus. The articles were selected to address the following research question: Which materials based on calcium silicate-based cements have hard tissue staining potential? The necessary information was extracted by 2 authors independently using a standardized form. The search resulted in 390 titles from all databases. Twenty-three studies met the inclusion criteria. Most of the studies exhibited a moderate risk of bias. The results indicated that some materials showed a strong potential for staining, including gray and white MTA Angelus (Londrina, PR, Brazil), gray and white ProRoot MTA (Dentsply, Tulsa, OK), and Ortho MTA (BioMTA, Seoul, Korea). Individual study results showed that Biodentine (Septodont, Saint Maur des Fosses, France), Retro MTA (BioMTA), Portland cement, EndoSequence Root Repair Material (Brasseler USA, Savannah, GA), Odontocem (Australian Dental Manufacturing, Brisbane, Australia), MM-MTA (Micro Mega, Besancon Cedex, France), and MTA Ledermix (Riemser Pharma GmbH, Greiswald-Insel Riems, Germany) were materials with the smallest staining potential. This review clearly showed that some calcium silicate-based cements have a high potential for staining hard tissue. On the other hand, some showed only a small change in color, which was

  20. Osteoclastic differentiation and resorption is modulated by bioactive metal ions Co2+, Cu2+ and Cr3+ incorporated into calcium phosphate bone cements.

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    Anne Bernhardt

    Full Text Available Biologically active metal ions in low doses have the potential to accelerate bone defect healing. For successful remodelling the interaction of bone graft materials with both bone-forming osteoblasts and bone resorbing osteoclasts is crucial. In the present study brushite forming calcium phosphate cements (CPC were doped with Co2+, Cu2+ and Cr3+ and the influence of these materials on osteoclast differentiation and activity was examined. Human osteoclasts were differentiated from human peripheral blood mononuclear cells (PBMC both on the surface and in indirect contact to the materials on dentin discs. Release of calcium, phosphate and bioactive metal ions was determined using ICP-MS both in the presence and absence of the cells. While Co2+ and Cu2+ showed a burst release, Cr3+ was released steadily at very low concentrations (below 1 μM and both calcium and phosphate release of the cements was considerably changed in the Cr3+ modified samples. Direct cultivation of PBMC/osteoclasts on Co2+ cements showed lower attached cell number compared to the reference but high activity of osteoclast specific enzymes tartrate resistant acid phosphatase (TRAP, carbonic anhydrase II (CAII and cathepsin K (CTSK and significantly increased gene expression of vitronectin receptor. Indirect cultivation with diluted Co2+ cement extracts revealed highest resorbed area compared to all other modifications and the reference. Cu2+ cements had cytotoxic effect on PBMC/osteoclasts during direct cultivation, while indirect cultivation with diluted extracts from Cu2+ cements did not provoke cytotoxic effects but a strictly inhibited resorption. Cr3+ doped cements did not show cytotoxic effects at all. Gene expression and enzyme activity of CTSK was significantly increased in direct culture. Indirect cultivation with Cr3+ doped cements revealed significantly higher resorbed area compared to the reference. In conclusion Cr3+ doped calcium phosphate cements are an innovative

  1. How effectively do hydraulic calcium-silicate cements re-mineralize demineralized dentin.

    Science.gov (United States)

    Li, Xin; De Munck, Jan; Van Landuyt, Kirsten; Pedano, Mariano; Chen, Zhi; Van Meerbeek, Bart

    2017-04-01

    To characterize the chemical interplay and to quantify the re-mineralization potential of hydraulic calcium-silicate cements (hCSCs) at demineralized dentin. Pairs of class-I cavities were prepared in non-carious human third molars. One dentin cavity was demineralized with 10% formic acid (5h); the other served as control. The cavities were filled with two resin-free hCSCs (Biodentine, Septodont; ProRoot MTA, Dentsply Sirona) or one resin-based hCSC (TheraCal LC, Bisco). After 1-week, 1-, 3-, and 6-month storage in simulated body fluid (SBF), polished specimen cross-sections were chemically characterized using Field-emission-gun Electron Probe Micro-Analysis (Feg-EPMA) and micro-Raman spectroscopy (μRaman). Feg-EPMA line-scans and elemental mappings confirmed early re-mineralization induced by all three hCSCs at 1week. The relative depth and intensity of re-mineralization were for the resin-free hCSCs in the range of 50.5%-84.8% and 68.1%-89.2%, respectively. Re-mineralization did not significantly differ for the storage periods (p>0.05). Significantly less re-mineralization was achieved by the resin-based hCSC TheraCal LC that reached only at 6months a re-mineralization level that was no longer significantly different from that achieved by the resin-free hCSCs at 1week (p>0.05). Re-mineralization of intertubular dentin, including tubular occlusion, was observed; Si was occasionally detected to have infiltrated the dentin tubules. Dentin re-mineralization by hCSCs was confirmed using μRaman that revealed an increased phosphate peak at 960cm(-1). hCSCs do re-mineralize demineralized dentin. The resin-free cements induced re-mineralization at a higher speed/intensity than the resin-based hCSC. However, re-mineralization was incomplete for all hCSCs tested, this even at 6months. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  2. Addition of Wollastonite Fibers to Calcium Phosphate Cement Increases Cell Viability and Stimulates Differentiation of Osteoblast-Like Cells

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    Juliana Almeida Domingues

    2017-01-01

    Full Text Available Calcium phosphate cement (CPC that is based on α-tricalcium phosphate (α-TCP is considered desirable for bone tissue engineering because of its relatively rapid degradation properties. However, such cement is relatively weak, restricting its use to areas of low mechanical stress. Wollastonite fibers (WF have been used to improve the mechanical strength of biomaterials. However, the biological properties of WF remain poorly understood. Here, we tested the response of osteoblast-like cells to being cultured on CPC reinforced with 5% of WF (CPC-WF. We found that both types of cement studied achieved an ion balance for calcium and phosphate after 3 days of immersion in culture medium and this allowed subsequent long-term cell culture. CPC-WF increased cell viability and stimulated cell differentiation, compared to nonreinforced CPC. We hypothesize that late silicon release by CPC-WF induces increased cell proliferation and differentiation. Based on our findings, we propose that CPC-WF is a promising material for bone tissue engineering applications.

  3. Current perspectives of bio-ceramic technology in endodontics: calcium enriched mixture cement - review of its composition, properties and applications

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    Shivani Utneja

    2015-02-01

    Full Text Available Advancements in bio-ceramic technology has revolutionised endodontic material science by enhancing the treatment outcome for patients. This class of dental materials conciliates excellent biocompatibility with high osseoconductivity that render them ideal for endodontic care. Few recently introduced bio-ceramic materials have shown considerable clinical success over their early generations in terms of good handling characteristics. Calcium enriched mixture (CEM cement, Endosequence sealer, and root repair materials, Biodentine and BioAggregate are the new classes of bio-ceramic materials. The aim of this literature review is to present investigations regarding properties and applications of CEM cement in endodontics. A review of the existing literature was performed by using electronic and hand searching methods for CEM cement from January 2006 to December 2013. CEM cement has a different chemical composition from that of mineral trioxide aggregate (MTA but has similar clinical applications. It combines the biocompatibility of MTA with more efficient characteristics, such as significantly shorter setting time, good handling characteristics, no staining of tooth and effective seal against bacterial leakage.

  4. Current perspectives of bio-ceramic technology in endodontics: calcium enriched mixture cement - review of its composition, properties and applications

    Science.gov (United States)

    Nawal, Ruchika Roongta; Talwar, Sangeeta; Verma, Mahesh

    2015-01-01

    Advancements in bio-ceramic technology has revolutionised endodontic material science by enhancing the treatment outcome for patients. This class of dental materials conciliates excellent biocompatibility with high osseoconductivity that render them ideal for endodontic care. Few recently introduced bio-ceramic materials have shown considerable clinical success over their early generations in terms of good handling characteristics. Calcium enriched mixture (CEM) cement, Endosequence sealer, and root repair materials, Biodentine and BioAggregate are the new classes of bio-ceramic materials. The aim of this literature review is to present investigations regarding properties and applications of CEM cement in endodontics. A review of the existing literature was performed by using electronic and hand searching methods for CEM cement from January 2006 to December 2013. CEM cement has a different chemical composition from that of mineral trioxide aggregate (MTA) but has similar clinical applications. It combines the biocompatibility of MTA with more efficient characteristics, such as significantly shorter setting time, good handling characteristics, no staining of tooth and effective seal against bacterial leakage. PMID:25671207

  5. Long-term biological performance of injectable and degradable calcium phosphate cement.

    Science.gov (United States)

    Grosfeld, Eline-Claire; Hoekstra, Jan Willem M; Herber, Ralf-Peter; Ulrich, Dietmar J O; Jansen, John A; van den Beucken, Jeroen J J P

    2016-12-09

    Enhancing degradation of poorly degrading injectable calcium phosphate (CaP) cements (CPCs) can be achieved by adding poly(lactic-co-glycolic acid) (PLGA) microparticles, generating porosity after polymer degradation. CPC-PLGA has proven to be biodegradable, although its long-term biological performance is still unknown. Optimization of injectability could be achieved via addition of carboxymethyl cellulose (CMC). Here, we evaluated the long-term in vivo performance of CPC-PLGA with or without the lubricant CMC in comparison to the devitalized bovine bone mineral (DBBM) predicate device Bio-Oss ® . Rabbit femoral bone defects were injected with a CPC-formulation or filled with Bio-Oss ® granules. Samples were retrieved at 6 and 26 weeks. Material degradation for Bio-Oss ® was marginal, starting with 57% material remnants at implantation, 49% at 6 weeks, and 35% at 26 weeks, respectively. In contrast, CPC-PLGA and CPC-PLGA-CMC showed significant material degradation, starting with 100% material remnants at implantation, 56 and 78% at 6 weeks, and 8 and 21% at 26 weeks. Bone formation showed to be rapid for Bio-Oss ® , with 24% at 6 weeks, and a similar value (27%) at 26 weeks. Both CPC-PLGA and CPC-PLGA-CMC showed a continuous temporal increase in bone formation, with 13 and 6% at 6 weeks, and 44 and 32% at 26 weeks. This study showed that CPC-PLGA induces favorable bone responses with  >90% degradation and  >40% new bone formation after an implantation period of 26 weeks.

  6. An experimental study on initial fixation strength in transpedicular screwing augmented with calcium phosphate cement.

    Science.gov (United States)

    Masaki, Taiga; Sasao, Yutaka; Miura, Takehiko; Torii, Yoshiaki; Kojima, Atsushi; Aoki, Haruhito; Beppu, Moroe

    2009-09-15

    An experimental study. To clarify the optimal insertion timing of transpedicular screws when the initial fixation strength reaches in maximum as calcium phosphate cement (CPC) hardens, in cases augmented by CPC to the vertebrae. CPC goes easily into the bone trabeculae and excels in the bone compatibility. However, it is still unknown as for differences of fixation effects by CPC hardening time at actual insertion of the pedicle screw. Fifty-seven vertebrae obtained from 11 human cadavers. The CPC and titanium pedicle screws were used. Experimental groups were decided as follows. (1) Control group (without CPC). (2) CPC group (augmented with CPC); the mixed CPC infused into the screw hole, afterwards the pedicle screw inserted at a set time (passage time from the initiation of powder and liquid agent mixing). The CPC group was further divided into 3 subgroups, with respect to insertion time of the pedicle screws: 2, 5, and 10 minute subgroups. Maximum pull-out strength was compared, and cross sectioned specimens of the 5 and 10 minute groups were prepared and observed. CPC group showed a pull-out strength of about 177% that of the control group. For inserting timing of the pedicle screw and pull-out strength, no apparent statistically significant difference was found between each subgroups, although the 10-minute group showed the lowest. Cross sectional observations revealed that the CPC diffused deeper into the bone trabeculae in the 5-minute group than in the 10 minutes. CPC augmentation enabled an average 77% increase of the maximum pull-out strength compared to the control group. The study of screw insertion timing augmented with CPC was indicative of the fact that an increase in the initial fixation of the pedicle screw can be achieved when the screw is inserted before initiation of CPC hardening.

  7. Thermodynamic variations in the decarbonation of low calcium fly ash-cement raw mix

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    Diouri, A.

    2005-03-01

    Full Text Available In this paper, the authors analyse the decomposition of a low lime saturation factor (LSF raw mix -obtained by adding low calcium fly ash to standard portland cement- when heated to around 1000 °C. The decarbonation temperatures and variation in enthalpy taking place during calcite decomposition were determined by DTA and isothermal calorimetric measurement. The resulting belitic clinker had a LSF factor ranging from 75 to 85%. The presence of fly ash was observed to retard the onset of decarbonation and lower the peak and final decarbonation temperatures. Decarbonation enthalpy was also found to decrease with fly ash content

    El objetivo del presente trabajo es estudiar durante su tratamiento térmico, alrededor de 1.000 °C, la evolución de la descomposición de un crudo que posee un factor de saturación de cal (LSF bajo. Este crudo se ha elaborado adicionando cenizas volantes bajas en calcio a un crudo de cemento portland ordinario. La temperatura de descarbonatación y la variación de la entalpia durante la descomposición de la calcita se determinan por ATD y calorimetría isotérmica. Los resultados muestran la formación de un clinker belítico con un LSF entre 85 y 75%. Asimismo, se demuestra que la presencia de cenizas volantes retarda el comienzo de la descarbonatación y disminuye la temperatura máxima y final del proceso de descarbonatación. El valor de la entalpia de la descarbonatación disminuye con la presencia de cenizas volantes.

  8. Effect of pH and Lidocaine on the Compressive Strength of Calcium Enriched Mixture Cement

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    Sobhnamayan F

    2015-12-01

    Full Text Available Statement of Problem: The pH of the human abscess has been measured as low as 5.0. This low pH could potentially inhibit setting reactions, affect adhesion, or increase the solubility of root end filling materials hence affect the compressive strength. Moreover, root end filling materials might expose or even mix with lidocaine HCL during periapical surgery. Objectives: The aim of this in vitro study was to evaluate the effect of acidic pH and lidocaine on the compressive strength of calcium-enriched mixture (CEM. Materials and Methods: CEM was mixed according to the manufacturer’s instructions or with lidocaine (L, and condensed into 6 × 4 mm split moulds. The samples were exposed to phosphate buffered saline (PBS at pH 5 or 7.4 for 7 or 28 days. Cylindrical blocks of CEM (total number = 120 and 15 for each group were subjected to compressive strength test using a universal testing machine. Data were analysed using three-factor analysis of variance (ANOVA. Results: Regardless of pH and time, significant differences were not found between lidocaine groups and the groups that were mixed according to the manufacturer’s instruction (p = 0.083. For both mixing agents, regardless of time, there were no significant differences between the two pH levels (p = 0.157. Regardless of the material and pH, there was a significant increase in the compressive strength from days 7 to 28 (p < 0.001. Conclusions: Mixtures with lidocaine and exposure to an acidic environment had no adverse effects on the compressive strength of CEM Cement.

  9. Calcium phosphate cement as an alternative for formocresol in primary teeth pulpotomies

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    Bijimole Jose

    2013-01-01

    Full Text Available Background: Formocresol remains to be the preferred medicament in pulpotomy, despite the concerns regarding tissue devitalization and systemic toxicity. Several materials were used as alternatives, but none proved significantly advantageous. Of recent, calcium phosphate cement (CPC has been projected as an ideal pulpotomy material considering its tissue compatibility and dentinogenic properties. This study explores the suitability of a CPC formulation for pulpotomy, in comparison with formocresol. Materials and Methods: This comparative case study included 10 children (8-12 age group having a pair of non-carious primary canines (both maxillary and mandibular posted for extraction. Pulpotomy was performed with CPC in the right canines and formocresol in the left and sealed with IRM ® (Dentsply. The teeth were extracted at 70 ± 5 days and sectioned and stained for the histopathological evaluation. Parameters such as pulpal inflammation, tissue reaction to material, dentine bridge formation, location of dentine bridge, quality of dentine formation in bridge, and connective tissue in bridge etc. were evaluated. Results: The histological assessment after 70 days showed no statistically significant difference between the two groups in any of the parameters. However, CPC gave more favorable results in pulpal inflammation, with a lower score of 1.6 against 2.6 for formocresol. CPC samples showed better formation of dentine bridge in quantity and quality. The mean scores for CPC for the extent of dentine bridge formation, quality of dentine bridge and connective tissue in the bridge, were 2.0, 1.4, and 1.2 respectively, whereas the corresponding values for formocresol were 0.8, 0.2, and 1.0. Conclusion: CPC is more compatible to pulp tissues than formocresol and it shows good healing potential. CPC is capable of inducing dentine formation without an area of necrosis.

  10. Setting time and formability of calcium phosphate cements prepared using modified dicalcium phosphate anhydrous powders.

    Science.gov (United States)

    Sawamura, Takenori; Mizutani, Yoichiro; Okuyama, Masahiko; Kasuga, Toshihiro

    2014-07-01

    Calcium phosphate cements (CPCs) were prepared using Ca4(PO4)2O (TeCP) and modified CaHPO4 (DCPA) to evaluate the effects of the powder properties for DCPA particles on the setting time and formability of the resulting CPCs. Two types of modified DCPA were prepared by milling commercially available DCPA with ethanol (to produce E-DCPA) or distilled water (to produce W-DCPA). The E-DCPA samples consisted of well-dispersed, fine primary particles, while the W-DCPA samples contained agglomerated particles, and had a smaller specific surface area. The mean particle size decreased with increased milling time in both cases. The raw CPC powders prepared using W-DCPA had a higher packing density than those prepared using E-DCPA, regardless of the mean particle size. The setting time of the CPC paste after mixing with distilled water decreased with decreases in the mean particle size and specific surface area, for both types of DCPA. The CPCs prepared using W-DCPA showed larger plasticity values compared with those prepared using E-DCPA, which contributed to the superior formability of the W-DCPA samples. The CPCs prepared using W-DCPA showed a short setting time and large plasticity values, despite the fact that only a small amount of liquid was used for the mixing of the raw CPC powders (a liquid-to-powder ratio of 0.25 g g(-1) was used). It is likely that the higher packing density of the raw CPC powders prepared using W-DCPA was responsible for the higher performance of the resulting CPCs.

  11. Sustainable Nanopozzolan Modified Cement: Characterizations and Morphology of Calcium Silicate Hydrate during Hydration

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    N. Mohamed Sutan

    2015-01-01

    Full Text Available There are environmental and sustainable benefits of partially replacing cement with industrial by-products or synthetic materials in cement based products. Since microstructural behaviours of cement based products are the crucial parameters that govern their sustainability and durability, this study investigates the microstructural comparison between two different types of cement replacements as nanopozzolan modified cement (NPMC in cement based product by focusing on the evidence of pozzolanic reactivity in corroboration with physical and mechanical properties. Characterization and morphology techniques using X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, energy-dispersive X-ray spectroscopy (EDS, and scanning electron microscopy (SEM were carried out to assess the pozzolanic reactivity of cement paste modified with the combination of nano- and micro silica as NPMC in comparison to unmodified cement paste (UCP of 0.5 water to cement ratio (w/c. Results were then substantiated with compressive strength (CS results as mechanical property. Results of this study showed clear evidence of pozzolanicity for all samples with varying reactivity with NPMC being the most reactive.

  12. Healing of segmental ulnar defects in dog using bioresorbable calcium phosphate cement added with recombinant human bone morphogenetic protein-2

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    Ohura, K.; Hamanishi, C. [Kinki Univ. School of Medicine, Osaka (Japan). Dept. of Orthopaedic Surgery; Irie, H. [Olympus Optical Co., Ltd., Tokyo (Japan)

    2001-07-01

    Bioresorbable calcium phosphate cement (BCPC) cylinders soaked with 100 {mu}g of rhBMP-2 were implanted into 21 mm segmental ulnar defects in dogs. New bone induced around cylinders united both bone segments in 3 weeks. As the cylinder dissolved, the induced bone was remodeled into the compact bone by 9 weeks. However, the cement cylinder implanted without BMP did not dissolve and that defect did not recover bone continuity in 9 weeks. Mechanical test at 9 weeks showed that the BMP group achieved 71% union and 63% of bone strength compared to normal ulna. However, other two groups, the implantation of the cylinder alone and no implantation, did not unite any case. The implantation of thin cylinders of BCPC soaked with small amount of rhBMP-2 repaired large bone defects of high mammal fast. Added with more BMP, it will be possible to apply this biocompatible composite even in clinical cases. (orig.)

  13. Effect of Expansive Admixtures on the Shrinkage and Mechanical Properties of High-Performance Fiber-Reinforced Cement Composites

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    Won-Chang Choi

    2013-01-01

    Full Text Available High-performance fiber-reinforced cement composites (HPFRCCs are characterized by strain-hardening and multiple cracking during the inelastic deformation process, but they also develop high shrinkage strain. This study investigates the effects of replacing Portland cement with calcium sulfoaluminate-based expansive admixtures (CSA EXAs to compensate for the shrinkage and associated mechanical behavior of HPFRCCs. Two types of CSA EXA (CSA-K and CSA-J, each with a different chemical composition, are used in this study. Various replacement ratios (0%, 8%, 10%, 12%, and 14% by weight of cement of CSA EXA are considered for the design of HPFRCC mixtures reinforced with 1.5% polyethylene (PE fibers by volume. Mechanical properties, such as shrinkage compensation, compressive strength, flexural strength, and direct tensile strength, of the HPFRCC mixtures are examined. Also, crack width and development are investigated to determine the effects of the EXAs on the performance of the HPFRCC mixtures, and a performance index is used to quantify the performance of mixture. The results indicate that replacements of 10% CSA-K (Type 1 and 8% CSA-J (Type 2 considerably enhance the mechanical properties and reduce shrinkage of HPFRCCs.

  14. In vitro cytotoxicity of four calcium silicate-based endodontic cements on human monocytes, a colorimetric MTT assay

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    Sedigheh Khedmat

    2014-08-01

    Full Text Available Objectives This study was performed to evaluate the cytotoxicity of four calcium silicate-based endodontic cements at different storage times after mixing. Materials and Methods Capillary tubes were filled with Biodentine (Septodont, Calcium Enriched Mixture (CEM cement, BioniqueDent, Tech Biosealer Endo (Tech Biosealer and ProRoot MTA (Dentsply Tulsa Dental. Empty tubes and tubes containing Dycal were used as negative and positive control groups respectively. Filled capillary tubes were kept in 0.2 mL microtubes and incubated at 37℃. Each material was divided into 3 groups for testing at intervals of 24 hr, 7 day and 28 day after mixing. Human monocytes were isolated from peripheral blood mononuclear cells and cocultered with 24 hr, 7 day and 28 day samples of different materials for 24 and 48 hr. Cell viability was evaluated using an MTT assay. Results In all groups, the viability of monocytes significantly improved with increasing storage time regardless of the incubation time (p < 0.001. After 24 hr of incubation, there was no significant difference between the materials regarding monocyte viability. However, at 48 hr of incubation, ProRoot MTA and Biodentine were less cytotoxic than CEM cement and Biosealer (p < 0.01. Conclusions Biodentine and ProRoot MTA had similar biocompatibility. Mixing ProRoot MTA with PBS in place of distilled water had no effect on its biocompatibility. Biosealer and CEM cement after 48 hr of incubation were significantly more cytotoxic to on monocyte cells compared to ProRoot MTA and Biodentine.

  15. Anti-inflammation performance of curcumin-loaded mesoporous calcium silicate cement

    Directory of Open Access Journals (Sweden)

    Yuan-Chien Chen

    2017-09-01

    Conclusion: Adding curcumin in MesoCS cements can reduce the inflammatory reaction, but does not affect the original biological activity and properties of MesoCS cements. It can provide a good strategy to inhibit the inflammatory reaction after implantation for bone tissue engineering and bone regenerative medicine.

  16. Calcium hydroxide poisoning

    Science.gov (United States)

    Hydrate - calcium; Lime milk; Slaked lime ... Calcium hydroxide ... These products contain calcium hydroxide: Cement Limewater Many industrial solvents and cleaners (hundreds to thousands of construction products, flooring strippers, brick cleaners, cement ...

  17. Effect of Propylene Glycol on the Sealing Ability of Mineral Trioxide Aggregate and Calcium-Enriched Mixture Cement Apical Barriers.

    Science.gov (United States)

    Adl, Alireza; Sobhnamayan, Fereshte; Shojaee, Nooshin Sadat; Tahmasebi Azad, Fateme; Bahmani, Mohsen

    2017-01-01

    Propylene glycol (PG) improves the handling, physical, and chemical properties of mineral trioxide aggregate (MTA). This study aimed to evaluate the effect of PG on the sealing ability of MTA and calcium-enriched mixture (CEM) apical barriers. A total of 70 extracted human maxillary single-rooted teeth were prepared using ProTaper rotary system. The apical 3 mm of the root tips were resected and the root canals were enlarged with Peeso reamers up to #4, to create open apex teeth. The teeth were then randomly divided into four experimental (n=15) and two control (n=5) groups. Group1: MTA+ MTA liquid, group2; MTA+MTA liquid (80%) + PG (20%), group3; CEM+CEM liquid, group4; CEM+ liquid (80%) + PG (20%). Cements were mixed with their respective mixing agents and a 4-mm thick apical plug was fabricated. The microleakage was measured on day 1, 3, 7 and 21 using a fluid filtration technique. The repeated measures ANOVA and Sidak test were used to analyze the data. All experimental groups demonstrated various amounts of microleakage. No significant difference was found between MTA and CEM cement (P=0.193), regardless of time and liquid components. There was no significant difference was observed between liquids (P=0.312) in all time intervals. The rate of microleakage decreased over time and a significant differences was observed between all intervals (PMTA and CEM cement.

  18. Swelling behavior of ion exchange resins incorporated in tri-calcium silicate cement matrix: II. Mechanical analysis

    Energy Technology Data Exchange (ETDEWEB)

    Neji, M., E-mail: mejdi.neji@cea.fr [CEA, DEN, DPC, SECR, Laboratoire d' Etude du Comportement des Bétons et des Argiles, F-91191 Gif-sur-Yvette (France); Polytech Lille, LML UMR, 8107 Villeneuve d' Ascq (France); Bary, B.; Le Bescop, P. [CEA, DEN, DPC, SECR, Laboratoire d' Etude du Comportement des Bétons et des Argiles, F-91191 Gif-sur-Yvette (France); Burlion, N. [Polytech Lille, LML UMR, 8107 Villeneuve d' Ascq (France)

    2015-12-15

    This paper presents the second part of a study aiming at modelling the mechanical behavior of composites made up of ion exchange resins (IER) solidified in a tri-calcium silicate cement paste (C{sub 3}S). Such composites may be subjected to internal pressures due to ion exchange processes between ionic species which are in IER and interstitial solution of the cement paste. The reactive transport model developed in the companion paper is coupled in this study to a multi-scale approach describing the mechanical behavior of the material. It is based on an analogy with thermomechanics for taking in account the IER internal pressures, and on Eshelby-based homogenization techniques to estimate both mechanical and coupling parameters. A laboratory test has been set up to measure the macroscopic strain caused by the swelling phenomenon. The model has been finally implemented in a finite elements software. The simulation of the laboratory tests has been performed and the results have been analyzed and compared to experimental data. - Highlights: • Experimental analysis about mechanical behavior of a composite material. • Chemo-Mechanical-Transport modeling on a composite material made up with IER embedded into cement paste matrix. • Multi-scale modeling.

  19. Swelling behavior of ion exchange resins incorporated in tri-calcium silicate cement matrix: I. Chemical analysis

    Energy Technology Data Exchange (ETDEWEB)

    Neji, M., E-mail: mejdi.neji@cea.fr [CEA, DEN, DPC, SECR, Laboratoire d' Etude du Comportement des Bétons et des Argiles, F-91191 Gif-sur-Yvette (France); Polytech Lille – LML UMR, 8107 Villeneuve d' Ascq (France); Bary, B.; Le Bescop, P. [CEA, DEN, DPC, SECR, Laboratoire d' Etude du Comportement des Bétons et des Argiles, F-91191 Gif-sur-Yvette (France); Burlion, N. [Polytech Lille – LML UMR, 8107 Villeneuve d' Ascq (France)

    2015-12-15

    This paper presents the first part of a theoretical and experimental work aiming at modeling the chemo-mechanical behavior of composites made up of ion exchange resins (IER) solidified in a tri-calcium silicate cement paste (C{sub 3}S). Because of ion exchange processes, the volume change of the IER may cause internal pressures leading to the degradation of the material. In this study, a predictive modeling is developed for describing the chemical behavior of such material. It is based on thermodynamic equilibria to determine the evolution of the ion exchange processes, and the potential precipitation of portlandite in the composite. In parallel, a phenomenological study has been set up to understand chemical phenomena related to the swelling mechanisms. The model created has been finally implemented in a finite elements software; the simulation of a laboratory test has been performed and the results compared to experimental data. - Highlights: • Ion exchange theory to model the swelling behavior of Ion exchange resin. • Experimental phenomenon analysis about Chemo-mechanical interaction between IER and cement paste matrix. • Chemo-Transport modeling on a composite material made with IER embedded into cement paste matrix.

  20. Investigation of early growth of calcium hydroxide crystals in cement solution by soft x-ray transmission microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Harutyunyan, V. S.; Kirchheim, A. P.; Monteiro, P. J. M.; Aivazyan, A. P.; Fischer, P.

    2009-02-02

    Research on cement hydration was performed at the full-field soft transmission X-ray microscope XM-1 located at beamline 6.1.2 at the Advanced Light Source (ALS) in Berkeley CA which is operated by the Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California. A series of works [1-3] has been conducted using this microscope for the in situ observation and qualitative analysis of through-solution hydration products and products of topochemical reactions, which form in cementitious aqueous solutions. This paper studies the precipitation of the calcium hydroxide (CH) crystals from the cement solution. The analysis of successive images of the hydration process provides critical quantitative information about the growth rate of calcium hydroxide (CH) crystals, the supersaturation ratio, and the kinetic and diffusion coefficients of the growth process. ASTM Type II portland cement and 6% C{sub 4}A{sub 3}{bar S} admixture were mixed in aqueous solution and saturated with respect to CH and gypsum. The C{sub 4}A{sub 3}{bar S} admixture was included in the experimental program because of the general research program on expansive cements, and adding C{sub 4}A{sub 3}{bar S} to portland cement is an efficient method of generating ettringite and significant early-age expansion. The solution/solid materials ratio was 10 cm{sup 3}/g, which is higher than the one existing in regular concrete and mortars; to compensate for this dilution, the solution was originally saturated with CH and gypsum. To allow sufficient transmission of the soft X-rays, a small droplet was taken from the supernatant solution and assembled in the sample holder, and then squeezed between two silicon nitride windows for the analysis. The X-ray optical setup of the microscope XM-1 is described elsewhere [2]. In this experiment, a wavelength of 2.4 nm (516.6 eV) was used. The radiation transmitting the sample was detected using an X-ray CCD camera, with a resolution of 35 nm provided

  1. Evaluation of optical density of bone defects filled with calcium phosphate cement and bioactive glass in rats.

    Science.gov (United States)

    Biancon Filho, Luiz Alberto; Primo, Bruno Tochetto; Gassen, Humberto Thomazi; Fontanella, Vânia Regina Camargo; Silva, Aurelício Novaes

    2011-02-01

    To evaluate new bone formation, by the analysis of optical density, in rat femoral defects filled with calcium phosphate cement (CPC) and bioactive glass (BG). Twenty-one rats were divided into three groups, Group I (CPC), Group II (BG), and Group III (control), and assessed after 7, 15, and 30 days. Three bone cavities were made in the left femur and filled with CPC, BG, and no material (control). Digital images were obtained and the results were subjected to statistical analysis of variance (ANOVA), complemented by the Friedman and Kruskal-Wallis nonparametric tests, with a significance level of 5%. Regarding optical density, Group I showed statistical values significantly higher than Group III and also higher, although not statistically significant, than Group II, in all observation periods. When Groups II and III were compared, Group II showed higher optical density values, without statistically significant differences, in all periods. The biomaterials analyzed showed higher optical density in relation to the control group in all observation periods, calcium phosphate cement being the best option in the repair of bone defects, but without statistically significant differences in relation to bioactive glass.

  2. Minimally invasive opening wedge tibia outpatient osteotomy, using screw-to-plate locking technique and a calcium phosphate cement.

    Science.gov (United States)

    Schwartz, Claude

    2018-01-10

    Medial knee osteoarthritis on angular varus deformity of a lower limb is very common. Open-wedge high tibial osteotomy is a treatment of choice if cartilage is not excessively worn (Allback 1 or 2). The technique based on a plate fixation and the bone defect filled with calcium phosphate cement is thoroughly described. Data at 1, 3, 6 months and 1 year of a 19 cases continuous and prospective series are collected and analysed. Mean age at the time of operation was 55 years. The average preoperative varus deformity was 5° and corrected to an average postoperative valgus of 4° (range 3°-6°). Each control includes the collection of eventual complications, the measurement of health status (quality of life and functional scores) and antero-posterior and lateral X-rays. All osteotomies were considered healed at 6 weeks without any correction loss except one, probably result of a technical error. There was no difference in clinical and functional results between the group and the literature, but the final result occurred earlier in the treatment when the bone defect was filled with either calcium phosphate cement. Faster recovery involved no specific complication and enabled outpatient treatment in a majority of patients.

  3. Shear bond strength of calcium enriched mixture cement and mineral trioxide aggregate to composite resin with two different adhesive systems.

    Directory of Open Access Journals (Sweden)

    Siavash Savadi Oskoee

    2014-12-01

    Full Text Available Immediate restoration after vital pulp therapy is essential in order to create and maintain effective coronal seal.The aim of this study was to evaluate the shear bond strength of recently used pulp capping materials: white mineral trioxide aggregate (MTA, and calcium enriched mixture cement (CEM to composite resin with the use of etch-and-rinse and self-etch adhesive systems and compare them with the bond strength of commonly used resin modified glass ionomer (RMGI cement.Forty specimens from each test material were fabricated, measuring 4 mm in diameter and 2 mm in depth. The specimens of each material were divided into 2 groups of 20 specimens according to the adhesive system (Single Bond vs. Clearfil SE Bond used for bonding of resin composite. The shear bond strength values were measured at a crosshead speed of 1.0 mm/min and fractured surfaces were examined. Data were analyzed using two-way ANOVA and a post hoc Tukey's test (P<0.05.Analysis of data showed a significantly higher bond strength for RMGI compared to MTA and CEM (P<0.001; however, no significant differences were observed in the bond strength values of MTA and CEM (P=0.9. Furthermore, there were no significant differences in relation to the type of the adhesive system irrespective of the type of the material used (P=0.95 All the failures were of cohesive type in RMGI, MTA and CEM.Bond strength of RMGI cement to composite resin was higher than that of MTA or CEM cement irrespective of the type of the adhesive system.

  4. A novel strontium(II)-modified calcium phosphate bone cement stimulates human-bone-marrow-derived mesenchymal stem cell proliferation and osteogenic differentiation in vitro.

    Science.gov (United States)

    Schumacher, M; Lode, A; Helth, A; Gelinsky, M

    2013-12-01

    In the present study, the in vitro effects of novel strontium-modified calcium phosphate bone cements (SrCPCs), prepared using two different approaches on human-bone-marrow-derived mesenchymal stem cells (hMSCs), were evaluated. Strontium ions, known to stimulate bone formation and therefore already used in systemic osteoporosis therapy, were incorporated into a hydroxyapatite-forming calcium phosphate bone cement via two simple approaches: incorporation of strontium carbonate crystals and substitution of Ca(2+) by Sr(2+) ions during cement setting. All modified cements released 0.03-0.07 mM Sr(2+) under in vitro conditions, concentrations that were shown not to impair the proliferation or osteogenic differentiation of hMSCs. Furthermore, strontium modification led to a reduced medium acidification and Ca(2+) depletion in comparison to the standard calcium phosphate cement. In indirect and direct cell culture experiments with the novel SrCPCs significantly enhanced cell proliferation and differentiation were observed. In conclusion, the SrCPCs described here could be beneficial for the local treatment of defects, especially in the osteoporotic bone. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  5. Effect of Exposed Surface Area, Volume and Environmental pH on the Calcium Ion Release of Three Commercially Available Tricalcium Silicate Based Dental Cements

    Directory of Open Access Journals (Sweden)

    Sivaprakash Rajasekharan

    2018-01-01

    Full Text Available Tricalcium silicate cements (TSC are used in dental traumatology and endodontics for their bioactivity which is mostly attributed to formation of calcium hydroxide during TSC hydration and its subsequent release of calcium and hydroxide ions. The aim of this study was to determine the effect of volume (Vol, exposed surface area (ESA and pH of surrounding medium on calcium ion release. Three commercially available hydraulic alkaline dental cements were mixed and condensed into cylindrical tubes of varying length and diameter (n = 6/group. For the effect of ESA and Vol, tubes were immersed in 10 mL of deionized water. To analyze the effect of environmental pH, the tubes were randomly immersed in 10 mL of buffer solutions with varying pH (10.4, 7.4 or 4.4. The solutions were collected and renewed at various time intervals. pH and/or calcium ion release was measured using a pH glass electrode and atomic absorption spectrophotometer respectively. The change of pH, short-term calcium ion release and rate at which calcium ion release reaches maximum were dependent on ESA (p < 0.05 while maximum calcium ion release was dependent on Vol of TSC (p < 0.05. Maximum calcium ion release was significantly higher in acidic solution followed by neutral and alkaline solution (p < 0.05.

  6. Effect of Exposed Surface Area, Volume and Environmental pH on the Calcium Ion Release of Three Commercially Available Tricalcium Silicate Based Dental Cements.

    Science.gov (United States)

    Rajasekharan, Sivaprakash; Vercruysse, Chris; Martens, Luc; Verbeeck, Ronald

    2018-01-13

    Tricalcium silicate cements (TSC) are used in dental traumatology and endodontics for their bioactivity which is mostly attributed to formation of calcium hydroxide during TSC hydration and its subsequent release of calcium and hydroxide ions. The aim of this study was to determine the effect of volume (Vol), exposed surface area (ESA) and pH of surrounding medium on calcium ion release. Three commercially available hydraulic alkaline dental cements were mixed and condensed into cylindrical tubes of varying length and diameter ( n = 6/group). For the effect of ESA and Vol, tubes were immersed in 10 mL of deionized water. To analyze the effect of environmental pH, the tubes were randomly immersed in 10 mL of buffer solutions with varying pH (10.4, 7.4 or 4.4). The solutions were collected and renewed at various time intervals. pH and/or calcium ion release was measured using a pH glass electrode and atomic absorption spectrophotometer respectively. The change of pH, short-term calcium ion release and rate at which calcium ion release reaches maximum were dependent on ESA ( p < 0.05) while maximum calcium ion release was dependent on Vol of TSC ( p < 0.05). Maximum calcium ion release was significantly higher in acidic solution followed by neutral and alkaline solution ( p < 0.05).

  7. Tuning the Degradation Rate of Calcium Phosphate Cements by Incorporating Mixtures of Polylactic-co-Glycolic Acid Microspheres and Glucono-Delta-Lactone Microparticles

    NARCIS (Netherlands)

    Sariibrahimoglu, K.; An, J.; Oirschot, B.A.J.A. van; Nijhuis, A.W.G.; Eman, R.M.; Alblas, J.; Wolke, J.G.C.; Beucken, J.J.J.P van den; Leeuwenburgh, S.C.G.; Jansen, J.A.

    2014-01-01

    Calcium phosphate cements (CPCs) are frequently used as synthetic bone graft materials in view of their excellent osteocompatibility and clinical handling behavior. Hydroxyapatite-forming CPCs, however, degrade at very low rates, thereby limiting complete bone regeneration. The current study has

  8. rhBMP-2 delivered in a calcium phosphate cement accelerates bridging of critical-sized defects in rabbit radii.

    Science.gov (United States)

    Seeherman, Howard J; Azari, Kodi; Bidic, Sean; Rogers, Leif; Li, X Jian; Hollinger, Jeffrey O; Wozney, John M

    2006-07-01

    Treatment of segmental bone loss remains a challenge in skeletal repairs. This study was performed to evaluate the efficacy of the use of recombinant bone morphogenetic protein-2 (rhBMP-2) delivered in an injectable calcium phosphate cement (alpha bone substitute material [alpha-BSM]) to bridge critical-sized defects in the rabbit radius. Unilateral 20-mm mid-diaphyseal defects were created in the radii of thirty-six skeletally mature New Zealand White rabbits. The defects in twelve rabbits each were filled with 0.166 mg/mL rhBMP-2/alpha-BSM cement, 0.033 mg/mL rhBMP-2/alpha-BSM cement, or buffer/alpha-BSM cement. Six rabbits from each group were killed at four weeks, and six were killed at eight weeks. Serial radiographs were made to monitor defect-bridging and residual alpha-BSM carrier. A semiquantitative histological scoring system was used to evaluate defect-bridging. Histomorphometry was used to quantify residual alpha-BSM; trabecular bone area; trabecular bone volume fraction; and cortical length, width, and area. At four weeks, there had been more rapid resorption of alpha-BSM and filling of the defects with trabecular bone in the group treated with 0.166 mg/mL rhBMP-2/alpha-BSM than in the other two groups. Histomorphometry confirmed an increased trabecular area and volume fraction in this group compared with the other two groups. In both rhBMP-2/alpha-BSM-treated groups, the majority of the trabecular bone was formed by a direct process adjacent to the resorbing alpha-BSM. At eight weeks, complete cortical bridging and regeneration of the marrow space were present in all of the defects treated with 0.166 mg/mL rhBMP-2/alpha-BSM. That group also had reduced residual alpha-BSM and trabecular area and volume, compared with the other two groups, at eight weeks as a result of a rapid remodeling process. Treatment of a critical-sized defect in a rabbit radius with 0.166 mg/mL rhBMP-2/alpha-BSM injectable cement can result in bridging with cortical bone and a

  9. The effect of human blood on the setting and surface micro-hardness of calcium silicate cements.

    Science.gov (United States)

    Song, Minju; Yue, Wonyoung; Kim, Soyeon; Kim, Wooksung; Kim, Yaelim; Kim, Jeong-Woong; Kim, Euiseong

    2016-11-01

    The purpose of the present study was to evaluate the effects of human blood on the setting and microhardness of calcium silicate cements. Three types of silicate-based cements were used: ProRoot MTA (PMTA), OrthoMTA (OMTA), and RetroMTA (RMTA). Mixed cement was placed into polyethylene molds with lengths of 2 and 4 mm. After storage for 4 days under three different storage conditions, i.e., saline, saline after 5 min of human blood, and human blood, the polyethylene molds were removed. With the specimens set, the surface microhardness was measured using a Vickers microhardness tester, crystalline structure was analyzed with X-ray diffraction (XRD), and the surface characteristics were examined with scanning electron microscopy (SEM). All specimens of 4 mm in length were set with all materials, and the blood groups exhibited lower microhardnesses than did the saline groups (p blood, the numbers of specimens that set were significantly different across the materials (p blood group exhibited reduced microhardness. XRD showed changes of crystalline structure in the PMTA and OMTA blood group, whereas RMTA did not. SEM analysis revealed more rounded and homogeneous structures and demonstrated a clear lack of acicular or needle-like crystals in the PMTA and OMTA blood groups, while RMTA did not reveal substantial differences between the saline- and blood-stored groups. Blood contamination detrimentally affected the surface microhardnesses of all materials; furthermore, among the 2-mm specimens, blood contamination interfered with normal setting. Therefore, RMTA might be a more suitable choice when blood contamination is unavoidable due to limited depth. Clinical relevance RetroMTA might be a more suitable choice in situations in which blood contamination is unavoidable.

  10. In Vitro Spectrophotometry of Tooth Discoloration Induced by Tooth-Colored Mineral Trioxide Aggregate and Calcium-Enriched Mixture Cement.

    Science.gov (United States)

    Arman, Marjan; Khalilak, Zohreh; Rajabi, Moones; Esnaashari, Ehsan; Saati, Keyvan

    2015-01-01

    There are numerous factors that can lead to tooth discoloration after endodontic treatment, such as penetration of endodontic materials into the dentinal tubules during root canal treatment. The aim of this in vitro study was to compare discoloration induced by tooth colored mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cement in extracted human teeth. Thirty two dentin-enamel cuboid blocks (7×7×2 mm) were prepared from extracted maxillary central incisors. Standardized cavities were prepared in the middle of each cube, leaving 1 mm of enamel and dentin on the labial surface. The specimens were randomly divided into two study groups (n=12) and two positive and negative control groups (n=4). In either study groups the cavities were filled with MTA or CEM cement. The positive and negative control groups were filled with blood or left empty, respectively. The cavities were sealed with composite resin and stored in normal saline. Color measurement was carried out by spectrophotometry at different time intervals including before (T0), and 1 week (T1), 1 month (T2) and 6 months (T3) after placement of materials. Repeated-measures ANOVA was used to compare the discoloration between the groups; the material type was considered as the inter-subject factor. The level of significance was set at 0.05. No significant differences were detected between the groups in all time intervals (P>0.05). Tooth discoloration was similarly detectable with both of the two experimental materials.

  11. Calcium phosphate phase transformation produced by the interaction of the portland cement component of white mineral trioxide aggregate with a phosphate-containing fluid.

    Science.gov (United States)

    Tay, Franklin R; Pashley, David H; Rueggeberg, Frederick A; Loushine, Robert J; Weller, R Norman

    2007-11-01

    The bioactivity of mineral trioxide aggregate (MTA) has been attributed to its ability to produce hydroxyapatite in the presence of phosphate-containing fluids. It is known that stoichiometric hydroxyapatites do not exist in biological systems and do not contribute to the osteogenic potential of calcium phosphate-based biomaterials. Because Portland cement is the active ingredient in white MTA, we have characterized the calcium phosphate phases produced when set white Portland cement was immersed in phosphate-buffered saline using pH and turbidity measurements, scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy, electron diffraction, x-ray diffraction, and Fourier transform-infrared spectroscopy. An amorphous calcium phosphate phase was initially formed that transformed to an apatite phase, with the latter consisting of calcium-deficient, poorly crystalline, B-type carbonated apatite crystallites. Amorphous calcium phosphate is a key intermediate that precedes biological apatite formation in skeletal calcification. Thus, the clinical manifestations of bioactivity with the use of MTA may at least be partially attributed to the mineralization induction capacity of its Portland cement component.

  12. Bone regeneration in experimental animals using calcium phosphate cement combined with platelet growth factors and human growth hormone.

    Science.gov (United States)

    Emilov-Velev, K; Clemente-de-Arriba, C; Alobera-García, M Á; Moreno-Sansalvador, E M; Campo-Loarte, J

    2015-01-01

    Many substances (growth factors and hormones) have osteoinduction properties and when added to some osteoconduction biomaterial they accelerate bone neoformation properties. The materials included 15 New Zealand rabbits, calcium phosphate cement (Calcibon(®)), human growth hormone (GH), and plasma rich in platelets (PRP). Each animal was operated on in both proximal tibias and a critical size bone defect of 6mm of diameter was made. The animals were separated into the following study groups: Control (regeneration only by Calcibon®), PRP (regeneration by Calcibon® and PRP), GH (regeneration by Calcibon® and GH). All the animals were sacrificed at 28 days. An evaluation was made of the appearance of the proximal extreme of rabbit tibiae in all the animals, and to check the filling of the critical size defect. A histological assessment was made of the tissue response, the presence of new bone formation, and the appearance of the biomaterial. Morphometry was performed using the MIP 45 image analyser. ANOVA statistical analysis was performed using the Statgraphics software application. The macroscopic appearance of the critical defect was better in the PRP and the GH group than in the control group. Histologically greater new bone formation was found in the PRP and GH groups. No statistically significant differences were detected in the morphometric study between bone formation observed in the PRP group and the control group. Significant differences in increased bone formation were found in the GH group (p=0.03) compared to the other two groups. GH facilitates bone regeneration in critical defects filled with calcium phosphate cement in the time period studied in New Zealand rabbits. Copyright © 2014 SECOT. Published by Elsevier Espana. All rights reserved.

  13. Effect of immersion time of restorative glass ionomer cements and immersion duration in calcium chloride solution on surface hardness.

    Science.gov (United States)

    Shiozawa, Maho; Takahashi, Hidekazu; Iwasaki, Naohiko; Wada, Takahiro; Uo, Motohiro

    2014-12-01

    The objective of this study was to evaluate the effect of immersion time of restorative glass ionomer cements (GICs) and immersion duration in calcium chloride (CaCl2) solution on the surface hardness. Two high-viscosity GICs, Fuji IX GP and GlasIonomer FX-II, were selected. Forty-eight specimens were randomly divided into two groups. Sixty minutes after being mixed, half of them were immersed in a 42.7wt% CaCl2 solution for 10, 30, or 60min (Group 1); the remaining specimens were immersed after an additional 1-week of storage (Group 2). The surface hardness of the specimens was measured and analyzed with two-way ANOVA and the Tukey HSD test (α=0.05). The surface compositions were examined using energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The surface hardness of Group 1 significantly increased as the immersion duration in CaCl2 increased; that of Group 2 significantly increased only after 60-minute CaCl2 immersion. After CaCl2 immersion, the amounts of Ca increased as the immersion duration increased. The surface hardness after CaCl2 immersion significantly correlated with the amount of Ca in Group 1, but not in Group 2. The binding energy of the Ca2p peak was similar to that of calcium polyalkenoate. These findings indicated that the Ca ions from the CaCl2 solution created chemical bonds with the carboxylic acid groups in the cement matrix. Immersion of GICs in CaCl2 solution at the early stage of setting was considered to enhance the formation of the polyacid salt matrix; as a result, the surface hardness increased. Copyright © 2014. Published by Elsevier Ltd.

  14. Effect of addition of nano-hydroxyapatite on physico-chemical and antibiofilm properties of calcium silicate cements

    Directory of Open Access Journals (Sweden)

    Juliane Maria GUERREIRO-TANOMARU

    Full Text Available ABSTRACT Objective Mineral Trioxide Aggregate (MTA is a calcium silicate cement composed of Portland cement (PC and bismuth oxide. Hydroxyapatite has been incorporated to enhance mechanical and biological properties of dental materials. This study evaluated physicochemical and mechanical properties and antibiofilm activity of MTA and PC associated with zirconium oxide (ZrO2 and hydroxyapatite nanoparticles (HAn. Material and Methods White MTA (Angelus, Brazil; PC (70%+ZrO2 (30%; PC (60%+ZrO2 (30%+HAn (10%; PC (50%+ZrO2 (30%+HAn (20% were evaluated. The pH was assessed by a digital pH-meter and solubility by mass loss. Setting time was evaluated by using Gilmore needles. Compressive strength was analyzed by mechanical test. Samples were radiographed alongside an aluminum step wedge to evaluate radiopacity. For the antibiofilm evaluation, materials were placed in direct contact with E. faecalis biofilm induced on dentine blocks. The number of colony-forming units (CFU mL-1 in the remaining biolfilm was evaluated. The results were submitted to ANOVA and the Tukey test, with 5% significance. Results There was no difference in pH levels of PC+ZrO2, PC+ZrO2+HAn (10% and PC+ZrO2+HAn (20% (p>0.05 and these cements presented higher pH levels than MTA (p<0.05. The highest solubility was observed in PC+ZrO2+HAn (10% and PC+ZrO2+HAn (20% (p<0.05. MTA had the shortest initial setting time (p<0.05. All the materials showed radiopacity higher than 3 mmAl. PC+ZrO2 and MTA had the highest compressive strength (p<0.05. Materials did not completely neutralize the bacterial biofilm, but the association with HAn provided greater bacterial reduction than MTA and PC+ZrO2 (p<0.05 after the post-manipulation period of 2 days. Conclusions The addition of HAn to PC associated with ZrO2 harmed the compressive strength and solubility. On the other hand, HAn did not change the pH and the initial setting time, but improved the radiopacity (HAn 10%, the final setting time and

  15. CO2 Capture by Calcium Looping at Relevant Conditions for Cement Plants: Experimental Testing in a 30 kWth Pilot Plant

    OpenAIRE

    Arias Rozada, Borja; Alonso Carreño, Mónica; Abanades García, Juan Carlos

    2017-01-01

    Calcium looping technology has a high potential for capturing CO2 in cement plants as the CaO-rich purge from the calciner can be used to replace a sizable fraction of the CaCO3 used as feedstock. Integrating the CaL process into the cement plant requires the carbonator reactor to operate under new conditions (i.e., a higher carbonator CO2 load, a more active sorbent, smaller particle sizes). This work analyzes the impact of some of the new CaL operating conditions on the pe...

  16. Short-time pre-washing of brushite-forming calcium phosphate cement improves its in vitro cytocompatibility.

    Science.gov (United States)

    Kunisch, Elke; Maenz, Stefan; Knoblich, Marie; Ploeger, Frank; Jandt, Klaus D; Bossert, Joerg; Kinne, Raimund W; Alsalameh, Saifeddin

    2017-10-14

    A pre-washing protocol was developed for resorbable, brushite-forming calcium phosphate cements (CPCs) to avoid harmful in vitro effects on cells. CPC discs (JectOS+, Kasios; self-developed CPC) were pre-washed with repeated changes of phosphate-buffered saline (PBS; 24h total). Unwashed or PBS-pre-washed discs were incubated in culture medium (5% fetal calf serum; up to 10days) and then tested for their influence on pH/calcium/phosphate levels in H2O extracts. Effects on pH/calcium/phosphate levels in culture supernatants, and morphology, adherence, number, and viability of ATDC5 cells and adipose-tissue derived stem cells were analyzed in co-culture. Pre-washing did not alter CPC surface morphology or Ca/P ratio (scanning electron microscopy; energy-dispersive X-ray spectroscopy). However, acidic pH of unwashed JectOS+ and self-developed CPC (5.82; 5.11), and high concentrations of Ca (2.17; 2.40mM) and PO4 (38.15; 49.28mM) in H2O extracts were significantly counteracted by PBS-pre-washing (pH: 7.92; 7.92; Ca: 0.64; 1.11mM; PO4: 5.39-5.97mM). Also, PBS-pre-washing led to physiological pH (approx. 7.5) and PO4 levels (max. 5mM), and sub-medium Ca levels (0.5-1mM) in supernatants and normalized cell morphology, adherence, number, and viability. This CPC pre-washing protocol improves in vitro co-culture conditions without influencing its structure or chemical composition. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. ToF-SIMS images and spectra of biomimetic calcium silicate-based cements after storage in solutions simulating the effects of human biological fluids

    Science.gov (United States)

    Torrisi, A.; Torrisi, V.; Tuccitto, N.; Gandolfi, M. G.; Prati, C.; Licciardello, A.

    2010-01-01

    ToF-SIMS images were obtained from a section of a tooth, obturated by means of a new calcium-silicate based cement (wTCF) after storage for 1 month in a saline solutions (DPBS), in order to simulate the body fluid effects on the obturation. Afterwards, ToF-SIMS spectra were obtained from model samples, prepared by using the same cement paste, after storage for 1 month and 8 months in two different saline solutions (DPBS and HBSS). ToF-SIMS spectra were also obtained from fluorine-free cement (wTC) samples after storage in HBSS for 1 month and 8 months and used for comparison. It was found that the composition of both the saline solution and the cement influenced the composition of the surface of disks and that longer is the storage greater are the differences. Segregation phenomena occur both on the cement obturation of the tooth and on the surface of the disks prepared by using the same cement. Indirect evidences of formation of new crystalline phases are supplied.

  18. Addition of 1, 2 and 3% in mass of sodium alginate in calcium phosphate cement; Adicao de alginato de sodio a cimento de fosfato de calcio

    Energy Technology Data Exchange (ETDEWEB)

    Coelho, W.T.; Fernandes, J.M.; Vieira, R.S.; Thurmer, M.B.; Santos, L.A., E-mail: trajano@ufrgs.br [Universidade Federal do Rio Grande do Sul (LABIOMAT/UFRS), RS (Brazil)

    2011-07-01

    The calcium phosphate cement (CFC) are bone substitutes with great potential for use in orthopedics, traumatology and dentistry because of their biocompatibility, bioactivity, osteoconductivity and osteotransdutivity, and a paste that can be easily molded and placed into the surgical site. However, CFCs have low mechanical strength, which equals the maximum mechanical strength of trabecular bone. Aiming to evaluate the strength and time to handle a CFC phase composed mainly of alpha were added to sodium alginate (1%, 2% and 3% wt) and an accelerator handle in an aqueous medium. The cement powder was mixed with liquid takes 2 minutes and resigned in specimens and assessed for apparent density and porosity by the Archimedes method, X-ray diffraction and mechanical strength. We noticed a significant increase in mechanical properties of cement added sodium alginate. (author)

  19. Histological changes of an injectable rhBMP-2/calcium phosphate cement in vertebroplasty of rhesus monkey.

    Science.gov (United States)

    Bai, Bo; Yin, Zhixun; Xu, Qian; Lew, Megan; Chen, Yi; Ye, Jiandong; Wu, Jingming; Chen, Dongfeng; Zeng, Yanjun

    2009-08-15

    A histologic study of recombinant human bone morphogenetic protein-2/calcium phosphate cement (rhBMP-2/CPC) using adult rhesus monkeys in vivo. To evaluate the histologic changes of rhBMP-2/CPC in vertebroplasty and determine the feasibility of this bone substitution instead of polymethylmethacrylate (PMMA). Previous studies have shown that the new rhBMP-2/nanoscale CPC has a suitable strength and injection for vertebroplasty. However, the osteoinductive properties and biodegradable characteristics are still unclear. Percutaneous vertebroplasty (PVP) was performed in 4 adult rhesus monkeys of 2 groups. Ten vertebral bodies (VBs) from T10-L7 of each rhesus were selected, and the 20 VBs in each group were randomly divided into 3 subgroups. Subgroup A (rhBMP-2/CPC): 8 VBs, filled with rhBMP-2/CPC; Subgroup B (PMMA): 6 VBs, filled with injectable PMMA; Subgroup C (control): 6 VBs, filled with normal saline. The 2 rhesus monkeys from each of the groups were killed at 2 and 6 months after operation, respectively. Individual specimens from the 40 VBs were collected for histologic observation. In subgroup A, radiographic and histologic observations showed that the part of the rhBMP-2/CPC cement degraded with new bone and new vessel ingrowths, into the material, after 2 months. In addition, gaps, fibrous hyperplasia, or sclerotic callus were not found in the interface. After 6 months, the cement was nearly all replaced by mature bone tissue. In subgroup B, the inflammatory cell infiltration and fibrous membrane gapping were found after 2 months, and subsided partly at 6 months. But no new bone formation and material degradation were discovered. In subgroup C, the tunnels were filled with irregular new trabeculae after 2 months and unrecognizable from the surrounding mature bone after 6 months. It is confirmed that the rhBMP-2/CPC is an osteoinductive and biodegradable material (in animal trials). It may also be an alternative to PMMA in order to achieve biostabilization in

  20. [Histological changes of an injectable rhBMP-2/calcium phosphate cement in vertebroplasty of rhesus monkey].

    Science.gov (United States)

    Bai, Bo; Xu, Qian; Chen, Yi; Ye, Jian-dong; Wu, Jing-ming; Chen, Dong-feng

    2008-02-15

    The histological changes of rhBMP-2/calcium phosphate cement (CPC) were evaluated in vertebroplasty on nonhuman primate models in order to determine the feasibility of this carrier formulation instead of PMMA. Percutaneous vertebroplasty (PVP) was performed in 4 adult rhesus monkeys which were evenly distributed in two groups. Ten vertebral bodies(VBs) from T10 to L7, of each rhesus were selected, and the 20 VBs in each group were randomly divided into 3 sub-groups. Group A:8 VBs, filled with rhBMP-2/CPC; Group B:6 VBs, filled with injectable PMMA; Group C:6 VBs, as control, filled with normal saline. The 2 rhesus monkeys in each group were killed at 2 and 6 months after operation, respectively, and the specimens of all the 40 VBs were collected for histological examination. In group A,radiographic and histologic studies confirmed that part of the rhBMP-2/CPC cement degraded with new bone and new vessels ingrowth into the material after 2 months. No gap, fibrous hyperplasia or sclerotic callus was found in the interface. After six months, the cement was almost completely replaced by mature bone tissue. In group B, no new bone formation and material degradation but inflammatory cell infiltration and fibrous membrane gap were found 2 months after operation. After 6 months, the inflammatory cell infiltration subsided, the fibrous membrane gap became narrower, but there were still no new bone formation and material degradation. In group C, the tunnels were filled with irregular new trabeculae after 2 months and unrecognizable from the surrounding mature bone after 6 months, indicating the completion of bone healing. With the characteristic of osteo-induction, the rhBMP-2/CPC can accelerate the healing of vertebral bone in nonhuman primates. Bone substitution is synchronous with material degradation, and the complete degradation of this material in late stage can avoid the potential adverse effects of PMMA on contiguous vertebral fracture and annulus degeneration. It

  1. EFFECT OF MgO ON THE COMPOSITION AND PROPERTIES OF BELITE-BARIUM CALCIUM SULPHOALUMINATE CEMENT IN THE PRESENCE OF Na2O AND K2O

    Directory of Open Access Journals (Sweden)

    Jie Zhang

    2015-06-01

    Full Text Available The purpose of this study is to explore the effect of MgO (1 - 9 wt. % on the composition and properties of belite-barium calcium sulphoaluminate cement with additions of Na2O and K2O. The results show that 1 - 5 wt. % content of MgO can stabilize crystal types of M3-C3S, R-C3S and β-C2S. Moreover, MgO can promote the formation of C3S and C4AF, but has little effect on the formation of C2.75B1.25A3$ and C3A. The C3A/C4AF ratio is reduced by 22 % at 5 wt. % MgO, which indicates that appropriate MgO can decrease the liquid viscosity. In the presence of Na2O and K2O, the highest limit of incorporated amount of MgO is about 3 wt. %, which is higher than that in Portland cement clinker of 2 wt. %. Besides, MgO favors the formation of small C3S crystals in size of 4 - 20 μm. MgO enhances the hydration rate and mechanical property of cement at an optimal dosage (1 - 5 wt. %, beyond which an adverse effect could be resulted. At a MgO dosage of 5 wt. %, the compressive strengths of the cement at 1, 3, 7 and 28 days are 15.8, 39.3, 68.6 and 97.3 MPa, which increases by 116 %, 17 %, 10 % and 6 % respectively compared to the cement without MgO dopant. This study could lead to the effective use of magnesia-rich limestone in industrial production of belite-barium calcium sulphoaluminate cement.

  2. Using calcium silicate to regulate the physicochemical and biological properties when using β-tricalcium phosphate as bone cement

    Energy Technology Data Exchange (ETDEWEB)

    Kao, Chia-Tze; Huang, Tsui-Hsien [School of Dentistry, Chung Shan Medical University, Taichung, Taiwan (China); Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan (China); Chen, Yi-Jyun [School of Dentistry, Chung Shan Medical University, Taichung, Taiwan (China); Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan (China); Dental Department, Taichung Hospital, Ministry of Health and Welfare, Taichung City, Taiwan (China); Hung, Chi-Jr [School of Dentistry, Chung Shan Medical University, Taichung, Taiwan (China); Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan (China); Lin, Chi-Chang, E-mail: chichang31@gmail.com [Department of Chemical and Materials Engineering, Tunghai University, Taichung, Taiwan (China); Shie, Ming-You, E-mail: eviltacasi@gmail.com [Department of Chemical and Materials Engineering, Tunghai University, Taichung, Taiwan (China)

    2014-10-01

    β-Tricalcium phosphate (β-TCP) is an osteoconductive material. For this research we have combined it with a low degradation calcium silicate (CS) to enhance its bioactive and osteostimulative properties. To check its effectiveness, a series of β-TCP/CS composites with different ratios were prepared to make new bioactive and biodegradable biocomposites for bone repair. Regarding the formation of bone-like apatite, the diametral tensile strength as well as the ion release and weight loss of composites were compared both before and after immersions in simulated body fluid (SBF). In addition, we also examined the behavior of human dental pulp cells (hDPCs) cultured on β-TCP/CS composites. The results show that the apatite deposition ability of the β-TCP/CS composites improves as the CS content is increased. For composites with more than a 60% CS content, the samples become completely covered by a dense bone-like apatite layer. At the end of the immersion period, weight losses of 24%, 32%, 34%, 38%, 41%, and 45% were observed for the composites containing 0%, 20%, 40%, 80%, 80% and 100% β-TCP cements, respectively. In addition, the antibacterial activity of CS/β-TCP composite improves as the CS-content is increased. In vitro cell experiments show that the CS-rich composites promote human dental pulp cell (hDPC) proliferation and differentiation. However, when the CS quantity in the composite is less than 60%, the quantity of cells and osteogenesis protein of hDPCs is stimulated by Si released from the β-TCP/CS composites. The degradation of β-TCP and the osteogenesis of CS give strong reason to believe that these calcium-based composite cements will prove to be effective bone repair materials. - Highlights: • CS improved the physicochemical properties and osteogenic activity of β-TCP. • Higher CS in the composite, the shorter setting time and the higher DTS was found. • With a CS more than 40%, the osteogenesis and angiogenesis proteins were promoted by

  3. Effect of Combined Calcium Hydroxide and Accelerated Portland Cement on Bone Formation and Soft Tissue Healing in Dog Bone Lesions

    Directory of Open Access Journals (Sweden)

    Khorshidi H

    2015-09-01

    Full Text Available Statement of Problem: Recent literatures show that accelerated Portland cement (APC and calcium hydroxide Ca (OH2 may have the potential to promote the bone regeneration. However, certain clinical studies reveal consistency of Ca (OH2, as one of the practical drawbacks of the material when used alone. To overcome such inconvenience, the combination of the Ca (OH2 with a bone replacement material could offer a convenient solution. Objectives: To evaluate the soft tissue healing and bone regeneration in the periodontal intrabony osseous defects using accelerated Portland cement (APC in combination with calcium hydroxide Ca (OH2, as a filling material. Materials and Methods: Five healthy adult mongrel dogs aged 2-3 years old (approximately 20 kg in weight with intact dentition and healthy periodontium were selected for this study. Two one-wall defects in both mesial and distal aspects of the 3rd premolars of both sides of the mandible were created. Therefore, four defects were prepared in each dog. Three defects in each dog were randomly filled with one of the following materials: APC alone, APC mixed with Ca (OH2, and Ca (OH2 alone. The fourth defect was left empty (control. Upon clinical examination of the sutured sites, the amount of dehiscence from the adjacent tooth was measured after two and eight weeks, using a periodontal probe mesiodistally. For histometric analysis, the degree of new bone formation was estimated at the end of the eighth postoperative week, by a differential point-counting method. The percentage of the defect volume occupied by new osteoid or trabecular bone was recorded. Results: Measurement of wound dehiscence during the second week revealed that all five APCs had an exposure of 1-2 mm and at the end of the study all samples showed 3-4 mm exposure across the surface of the graft material, whereas the Ca (OH2, control, and APC + Ca (OH2 groups did not show any exposure at the end of the eighth week of the study. The most

  4. Successful Bone Union Following Calcium Phosphate Cement-Assisted Percutaneous Transpedicular Balloon Kyphoplasty of a Large Interbody Cleft on Long-term Hemodialysis Patient.

    Science.gov (United States)

    Ishiguro, Shigeo; Tsujii, Masaya; Sudo, Akihiro

    2011-09-01

    A 68-year-old diabetic man, who had been on dialysis for 3 years, suffered a five week history of severe back pain that was unresponsive to bed rest, analgesics, and bracing. The vertebral cleft formed by an injury gradually increased in size on sequential plain films. Hence, he underwent calcium phosphate cement-assisted percutaneous transpedicular balloon kyphoplasty to treat a painful interbody vacuum cleft. Immediate pain relief and firm bone union were obtained.

  5. Effect of saliva and blood contamination on the bi-axial flexural strength and setting time of two calcium-silicate based cements: Portland cement and biodentine.

    Science.gov (United States)

    Alhodiry, W; Lyons, M F; Chadwick, R G

    2014-03-01

    This study evaluated the effect of contamination with saliva and blood on the bi-axial flexural strength and setting time of pure gray Portland cement and Biodentine (Septodont, Allington, UK). A one-way ANOVA showed that contamination caused no significant difference between the cements in bi-axial flexural strength (P> 0.05). However there was a significant difference in setting time (PBiodentine, regardless of the contaminant, and contamination with blood increased the setting time of both materials. Biodentine was similar in strength to Portland cement, but had a shorter setting time for both contaminated and non-contaminated samples.

  6. Effect of Tartaric Acid on Hydration of a Sodium-Metasilicate-Activated Blend of Calcium Aluminate Cement and Fly Ash F

    Directory of Open Access Journals (Sweden)

    Tatiana Pyatina

    2016-05-01

    Full Text Available An alkali-activated blend of aluminum cement and class F fly ash is an attractive solution for geothermal wells where cement is exposed to significant thermal shocks and aggressive environments. Set-control additives enable the safe cement placement in a well but may compromise its mechanical properties. This work evaluates the effect of a tartaric-acid set retarder on phase composition, microstructure, and strength development of a sodium-metasilicate-activated calcium aluminate/fly ash class F blend after curing at 85 °C, 200 °C or 300 °C. The hardened materials were characterized with X-ray diffraction, thermogravimetric analysis, X-ray computed tomography, and combined scanning electron microscopy/energy-dispersive X-ray spectroscopy and tested for mechanical strength. With increasing temperature, a higher number of phase transitions in non-retarded specimens was found as a result of fast cement hydration. The differences in the phase compositions were also attributed to tartaric acid interactions with metal ions released by the blend in retarded samples. The retarded samples showed higher total porosity but reduced percentage of large pores (above 500 µm and greater compressive strength after 300 °C curing. Mechanical properties of the set cements were not compromised by the retarder.

  7. Calcium-magnesium carbonate solid solutions from Holocene conglomerate cements and travertines in the Coast Range of California

    Science.gov (United States)

    Barnes, I.; O'Neil, J.R.

    1971-01-01

    Two calcium-magnesium carbonate solid solutions form Holocene travertines and conglomerate cements in fresh water stream channels of the Coast Range of California. Calcite does not yield the {015} diffraction maximum. The {006} diffraction maximum is lacking over most of the range of composition of calcite. Calcite has compositions from CaCO3 to Ca0.5Mg0.5CO3. Dolomite yields both the {006} and {015} diffraction maxima over its entire composition range, Ca0.6Mg0.4CO3 to Ca0.5Mg0.5CO3. The Ca-Mg carbonates form in isotopic equilibrium and thermodynamic disequilibrium from dispersion of Ca2+-rich water into CO32--rich water within the alluvium. The stable isotope data suggest that all the Mg-rich carbonates are primary precipitates and not a result of Mg-substitution in precursor CaCO3. There is a correlation between ??C13 and Mg content of the carbonates which predicts a 5%. fractionation of C13 between dolomite and calcite at sedimentary temperatures. C14 is incorporated in Ca-Mg carbonates forming from C13-poor meteoric waters and C13-rich waters from Cretaceous sediments. C14 ages of the Ca-Mg carbonates are apparent, and cannot be corrected to absolute values. Solution rates of calcite decrease with increasing MgCO3 content; dolomite dissolves slower than any calcite. ?? 1971.

  8. Osseous reaction to implantation of two endodontic cements: Mineral trioxide aggregate (MTA) and calcium enriched mixture (CEM).

    Science.gov (United States)

    Rahimi, Saeed; Mokhtari, Hadi; Shahi, Shahriar; Kazemi, Ali; Asgary, Saeed; Eghbal, Mohammad-Jafar; Mesgariabbasi, Mehran; Mohajeri, Daryoush

    2012-09-01

    The aim of the present in vivo study was to determine bone tissue reaction to calcium enriched mixture (CEM) and mineral trioxide aggregate (MTA) using a rat femur model. Sixty-three rats were selected and randomly divided into three groups of 21 each [experimental groups (n=15), control (n=6)]. Implantation cavities were prepared in each femoral bone and randomly filled with the biomaterials only in the experimental groups. The animals in three groups were sacrificed 1, 4, and 8 weeks postoperatively. Histologic evaluations comprising inflammation severity and new bone formation were blindly made on H&E-stained decalcified 6-µm sections. At 1, 4, and 8 weeks after implantation number of inflammatory cells had decreased in the CEM, MTA and control groups, respectively, with no statistically significant differences. Conversely, new bone formation had increased in all the experimental and control groups, without statistically significant differences. The results suggest that biocompatibility of MTA, as gold standard, and CEM cement as a new endodontic biomaterial are comparable.

  9. Enhanced healing of rabbit segmental radius defects with surface-coated calcium phosphate cement/bone morphogenetic protein-2 scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yi; Hou, Juan; Yin, ManLi [Engineering Research Center for Biomedical Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237 (China); Wang, Jing, E-mail: biomatwj@163.com [Engineering Research Center for Biomedical Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237 (China); Liu, ChangSheng, E-mail: csliu@sh163.net [Engineering Research Center for Biomedical Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237 (China); The State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237 (China); Key Laboratory for Ultrafine Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237 (China)

    2014-11-01

    Large osseous defects remain a difficult clinical problem in orthopedic surgery owing to the limited effective therapeutic options, and bone morphogenetic protein-2 (BMP-2) is useful for its potent osteoinductive properties in bone regeneration. Here we build a strategy to achieve prolonged duration time and help inducting new bone formation by using water-soluble polymers as a protective film. In this study, calcium phosphate cement (CPC) scaffolds were prepared as the matrix and combined with sodium carboxymethyl cellulose (CMC-Na), hydroxypropylmethyl cellulose (HPMC), and polyvinyl alcohol (PVA) respectively to protect from the digestion of rhBMP-2. After being implanted in the mouse thigh muscles, the surface-modified composite scaffolds evidently induced ectopic bone formation. In addition, we further evaluated the in vivo effects of surface-modified scaffolds in a rabbit radius critical defect by radiography, three dimensional micro-computed tomographic (μCT) imaging, synchrotron radiation-based micro-computed tomographic (SRμCT) imaging, histological analysis, and biomechanical measurement. The HPMC-modified CPC scaffold was regarded as the best combination for segmental bone regeneration in rabbit radius. - Highlights: • A simple surface-coating method was used to fabricate composite scaffolds. • Growth factor was protected from rapid depletion via superficial coating. • Significant promotion of bone regeneration was achieved. • HPMC-modification displayed optimal effect of bone regeneration.

  10. Cytotoxic effects of mineral trioxide aggregate, calcium enriched mixture cement, Biodentine and octacalcium pohosphate on human gingival fibroblasts

    Directory of Open Access Journals (Sweden)

    Eshagh

    2016-06-01

    Full Text Available Background. This in vitro study compared the effects of mineral trioxide aggregate (MTA, calcium enriched mixture (CEM cement, Biodentine (BD and octacalcium phosphate (OCP on the viability of human gingival fibroblasts (HGFs. Methods. After completion of the setting time of the materials under study, fibroblasts were placed in 24-well insert plates and 1 mg of each material was added to the respective wells. The plates were then incubated at 37°C. The inserts were removed at 24, 48 and 168 hours and 2,5-diphenyltetrazolium bromide was added to assess cytotoxicity via the MTT colorimetric assay. Data were analyzed at different time intervals using repeated-measures ANOVA, followed by the Bonferroni test at three levels of significance of P < 0.05, P < 0.01 and P < 0.001. Results. Cytotoxicity of the materials under study was not significantly different at 24 and 48 hours compared to the control group. However, at 168 hours, a significant difference was noted between MTA (P< 0.05 and Biodentine (P < 0.01 and the control group. Conclusion. Cytotoxicity of MTA, CEM, Biodentine and OCP against HGFs was similar to that of the control group at 24 and 48 hours. Over time, MTA and Biodentine exhibited less cytotoxicity than other materials.

  11. Calcium aluminate cement concrete: durablllty and conversión. A fresh look at an old subject

    Directory of Open Access Journals (Sweden)

    George, C. M.

    1992-12-01

    Full Text Available This paper re-examines the relationship between durability and conversion of calcium aluminate cement concretes, CACC. Conversion is a natural and inevitable process whereby these materials reach a stable mature condition. Numerous structures built more than half a century ago remain serviceable and in service today. Some of these are illustrated. They are the best testament to the durability of converted concrete having survived far longer in the converted than the unconverted condition. The unique rapid hardening characteristics of CACC offer a valuable selfheating capability. Conversión is immediate and this leads to better long term strengths because more cement is hydrated. Moreover, recent work has shown that the thermodynamically stable hydrates of converted CAC are intrinsically more resistant to attack from such aggressive agents as sulphuric acid. This provides an explanation of the excellent long term performance of Fondu concretes, for example in many saewer applications. Our knowledge and understanding today of the durability of calcium alumínate bonded materials has been built on close to 100 years of accumulated experience and laboratory studies. We know how to use these materials and we know what to expect from them. We can be confident that they will serve us well in the century ahead.

    Este trabajo examina de nuevo la relación entre durabilidad y conversión de hormigones de cemento aluminoso, HAC (High Alumina Cement. La conversión es un proceso natural e inevitable a través del cual este material consigue una condición definitiva y estable. Numerosas estructuras que se edificaron hace más de medio siglo siguen utilizables y utilizadas hoy en día. Algunas de estas estructuras vienen ilustradas en este trabajo. Ellas sirven como mejor ejemplo de la durabilidad del hormigón convertido, ya que han sobrevivido mucho más tiempo en el estado convertido que en el no convertido. Las singulares caracter

  12. Adhesion mechanism of polyelectrolyte cements to tooth structure--polyelectrolyte behavior of the cement polymers obtained by potentiometric titration in the presence of calcium ion

    National Research Council Canada - National Science Library

    Iioka, A; Araki, Y; Matsuda, K; Ohno, H

    1989-01-01

    Potentiomeric titration of aqueous solutions of polyacrylic acid and commercial polyelectrolyte cement polymers with sodium hydroxide solution was carried out in the presence of different concentrations of Ca2...

  13. Preparation, characterization and investigation of in vitro and in vivo biological properties of strontium-modified calcium phosphate cement for bone defect repair

    Directory of Open Access Journals (Sweden)

    Reza Masaeli

    2015-12-01

    Full Text Available Background and Aims: The aim of this study was to evaluate the invitro and invivo performance of a 3 wt% of strontium additive hydroxyapatite calcium phosphate cements (CPC. Materials and Methods: The prepared calcium phosphate cement was characterized with XRD, FTIR, setting time, STA and in vitro and in vivo biological analyses. The MTT assay ALP activities as in vitro study and radiological and histological examinations as in vivo study between the three groups of 3 wt% Sr-HA/CPC, CPC and control were performed and compared. Data were analyzed using T-test and One-way ANOVA. Results: XRD analysis demonstrated that by increasing the ratio of Powder/Liquid (P/L, the crystallinity of the prepared cement increased. The substitution of strontium instead of calcium in CPC could also alter the crystal structure, including some structural disorder. However, in the CPC with no strontium hydroxyapatite (Sr-HA, no significant increase in the crystallinity was observed. SEM observations revealed CPC with increasing P/L ratio, the formation of hydroxyapatite crystals arising from the interaction of solid and liquid phase of cement was decreased. Also, the addition of Sr within Ca site culminated in a dramatic increase in crystallinity of hydroxyapatite. In vitro biological properties ascertained that addition of 3 wt. % Sr-HA into CPC enhanced MTT assay and ALP activity, which could be due to the presence of strontium ions. The histological study showed that greater remodeling was seen at 4 weeks after implantation when the 3 wt% Sr-HA/CPC was used. Conclusion: The obtained results cleared that CPC can be a potential candidate as a carrier with strontium additives for bone remodeling and regeneration.

  14. Human tooth germ stem cell response to calcium-silicate based endodontic cements

    Directory of Open Access Journals (Sweden)

    Esra Pamukcu Guven

    2013-07-01

    Full Text Available OBJECTIVE: The aim of this study was to compare the cytotoxic effects of endodontic cements on human tooth germ stem cells (hTGSCs. MTA Fillapex, a mineral trioxide aggregate (MTA-based, salicylate resin containing root canal sealer, was compared with iRoot SP, a bioceramic sealer, and AH Plus Jet, an epoxy resin-based root canal sealer. MATERIAL AND METHODS: To evaluate cytotoxicity, all materials were packed into Teflon rings (4 mmµ3 mm and co-cultured with hTGSCs with the aid of 24-well Transwell permeable supports, which had a pore size of 0.4 µm. Coverslips were coated with MTA Fillapex, iRoot SP and AH Plus Jet and each coverslip was placed onto the bottom of one well of a six-well plate for scanning electron microscopy (SEM analysis. Before the cytotoxicity and SEM analysis, all samples were stored at 37ºC and at 95% humidity and 5% CO2 for 24 hours to set. The cellular viability was analyzed using MTS test (3-(4,5-dimethyl-thiazol-2-yl-5-(3-carboxy-methoxy-phenyl-2-(4-sulfo-phenyl-2H-tetrazolium. The cytotoxic effects and SEM visualization of the tested materials were analyzed at 24-hour, 72-hour, one-week and two-week periods. RESULTS: On the 1st day, only MTA Fillapex caused cytotoxicity compared to negative control (NC group (p0.05. After 14 days of incubation with the test materials, MTA Fillapex exhibited significantly higher cytotoxicity compared with iRoot SP, AH Plus Jet and the NC group (P<0.008. In the SEM analysis, the highest levels of cell attachment were observed for iRoot SP and the control group. After 24 hours, MTA Fillapex reduced the number of cells attached to the surface. CONCLUSIONS: Within the limitations of this study, sealers exerted different cytotoxic effects on hTGSCs. Although all materials have exerted cellular toxicity, iRoot SP and AH Plus Jet may promote better attachment to hTGSCs.

  15. Human tooth germ stem cell response to calcium-silicate based endodontic cements.

    Science.gov (United States)

    Güven, Esra Pamukçu; Yalvaç, Mehmet Emir; Kayahan, Mehmet Baybora; Sunay, Hakkı; Şahın, Fikrettin; Bayirli, Gündüz

    2013-01-01

    The aim of this study was to compare the cytotoxic effects of endodontic cements on human tooth germ stem cells (hTGSCs). MTA Fillapex, a mineral trioxide aggregate (MTA)-based, salicylate resin containing root canal sealer, was compared with iRoot SP, a bioceramic sealer, and AH Plus Jet, an epoxy resin-based root canal sealer. To evaluate cytotoxicity, all materials were packed into Teflon rings (4 mmµ3 mm) and co-cultured with hTGSCs with the aid of 24-well Transwell permeable supports, which had a pore size of 0.4 µm. Coverslips were coated with MTA Fillapex, iRoot SP and AH Plus Jet and each coverslip was placed onto the bottom of one well of a six-well plate for scanning electron microscopy (SEM) analysis. Before the cytotoxicity and SEM analysis, all samples were stored at 37ºC and at 95% humidity and 5% CO2 for 24 hours to set. The cellular viability was analyzed using MTS test (3-(4,5-dimethyl-thiazol-2-yl)-5-(3-carboxy-methoxy-phenyl)-2-(4-sulfo-phenyl)-2H-tetrazolium). The cytotoxic effects and SEM visualization of the tested materials were analyzed at 24-hour, 72-hour, one-week and two-week periods. On the 1st day, only MTA Fillapex caused cytotoxicity compared to negative control (NC) group (p0.05). After 14 days of incubation with the test materials, MTA Fillapex exhibited significantly higher cytotoxicity compared with iRoot SP, AH Plus Jet and the NC group (P<0.008). In the SEM analysis, the highest levels of cell attachment were observed for iRoot SP and the control group. After 24 hours, MTA Fillapex reduced the number of cells attached to the surface. Within the limitations of this study, sealers exerted different cytotoxic effects on hTGSCs. Although all materials have exerted cellular toxicity, iRoot SP and AH Plus Jet may promote better attachment to hTGSCs.

  16. Calcium

    Science.gov (United States)

    ... Turn to calcium-fortified (or "calcium-set") tofu, soy milk, tempeh, soy yogurt, and cooked soybeans (edamame). Calcium-fortified foods. Look for calcium-fortified orange juice, soy or rice milk, breads, and cereal. Beans. You can get decent ...

  17. Evaluation of mineral trioxide aggregate (MTA) versus calcium hydroxide cement (Dycal(®) ) in the formation of a dentine bridge: a randomised controlled trial.

    Science.gov (United States)

    Leye Benoist, Fatou; Gaye Ndiaye, Fatou; Kane, Abdoul Wakhabe; Benoist, Henri Michel; Farge, Pierre

    2012-02-01

    To assess the effectiveness of mineral trioxide aggregate (MTA) used as an indirect pulp-capping material in human molar and premolar teeth. We conducted a clinical evaluation of 60 teeth, which underwent an indirect pulp-capping procedure with either MTA or calcium hydroxide cement (Dycal(®) ). Calcium hydroxide was compared with MTA and the thickness of the newly formed dentine was measured at regular time intervals. The follow-up was at 3 and 6 months, and dentine formation was monitored by radiological measurements on digitised images using Mesurim Pro(®) software. At 3 months, the clinical success rates of MTA and calcium hydroxide were 93% and 73%, respectively (P = 0.02). At 6 months, the success rate was 89.6% with MTA, and remained steady at 73% with calcium hydroxide (P = 0.63). The mean initial residual dentine thickness was 0.23 mm, and increased by 0.121 mm with MTA and by 0.136 mm with calcium hydroxide at 3 months. At 6 months, there was an increase of 0.235 mm with MTA and of 0.221 mm with calcium hydroxide.   A higher success rate was observed in the MTA group relative to the Dycal(®) group after 3 months, which was statistically significant. After 6 months, no statistically significant difference was found in the dentine thickness between the two groups. Additional histological investigations are needed to support these findings. © 2012 FDI World Dental Federation.

  18. Adhesion mechanism of polyelectrolyte cements to tooth structure--polyelectrolyte behavior of the cement polymers obtained by potentiometric titration in the presence of calcium ion.

    Science.gov (United States)

    Iioka, A; Araki, Y; Matsuda, K; Ohno, H

    1989-12-01

    Potentiomeric titration of aqueous solutions of polyacrylic acid and commercial polyelectrolyte cement polymers with sodium hydroxide solution was carried out in the presence of different concentrations of Ca2+. Polyelectrolytes all behave as weak acids without the coexisting Ca2+. However, in the presence of Ca2+, in amounts over one-half of the equivalent amount to the carboxyl group in the polymer, they have a strong acid-like behavior. This means that the carboxyl groups in the polymer chain tend to react strongly with coexisting Ca2+ as they are partially neutralized by the alkaline solution. This is also strong evidence supporting polyelectrolyte cement as an adhesion mechanism to tooth structure during cementation.

  19. Tantalum oxide and barium sulfate as radiopacifiers in injectable calcium phosphate-poly(lactic-co-glycolic acid) cements for monitoring in vivo degradation.

    Science.gov (United States)

    Hoekstra, Jan Willem M; van den Beucken, Jeroen J J P; Leeuwenburgh, Sander C G; Bronkhorst, Ewald M; Meijer, Gert J; Jansen, John A

    2014-01-01

    Monitoring the degradation of calcium phosphate-based bone substitute materials in vivo by means of noninvasive techniques (e.g., radiography) is often a problem due to the chemical resemblance of those substitutes with the mineral phase of bone. In the view of that, the present study aimed at enhancing the radiopacity of calcium phosphate cement enriched with poly(lactic-co-glycolic acid) (CPC-PLGA) microspheres, by adding tantalum oxide (Ta2O5) or the more traditional radiopacifier barium sulfate (BaSO4). The radiopacifying capacity of these radiopacifiers was first evaluated in vitro by microcomputed tomography (μCT). Thereafter, both radiopacifiers were tested in vivo using a distal femoral condyle model in rabbits, with subsequent ex vivo μCT analysis in parallel with histomorphometry. Addition of either one of the radiopacifiers proved to enhance radiopacity of CPC-PLGA in vitro. The in vivo experiment showed that both radiopacifiers did not induce alterations in biological performance compared to plain CPC-PLGA, hence both radiopacifiers can be considered safe and biocompatible. The histomorphometrical assessment of cement degradation and bone formation showed similar values for the three experimental groups. Interestingly, μCT analysis showed that monitoring cement degradation becomes feasible upon incorporation of either type of radiopacifier, albeit that BaSO4 showed more accuracy compared to Ta2O5. Copyright © 2013 Wiley Periodicals, Inc., a Wiley Company.

  20. A prospective clinical trial on the influence of a triamcinolone/demeclocycline and a calcium hydroxide based temporary cement on pain perception

    Directory of Open Access Journals (Sweden)

    Willershausen Brita

    2012-03-01

    Full Text Available Abstract Introduction The aim of this clinical trial was to compare the degree of short term post-operative irritation after application of a triamcinolone/demeclocycyline based or a calcium hydroxide based provisional cement. Methods A total of 109 patients (55 female and 54 male; mean age: 51 ± 14 years with primary or secondary dentinal caries were randomly assigned to the two treatment groups of this biomedical clinical trial (phase III. Selection criteria were good systemic health and treated teeth, which were vital and showed no symptoms of pulpitis. Up to three teeth were prepared for indirect metallic restorations, and the provisional restorations were cemented with a triamcinolone/demeclocycyline (Ledermix or a calcium hydroxide (Provicol based material. The intensity of post-operative pain experienced was documented according to the VAS (4, 12, 20, 24, and 82 h and compared to VAS baseline. Results A total of 159 teeth were treated (Ledermix: 83 teeth, Provicol: 76 teeth. The minor irritation of the teeth, experienced prior to treatment, was similar in both groups; however, 4 h after treatment this value was significantly higher in the Provicol group than in the Ledermix group (p Conclusions The patients had no long term post-operative pain experience in both groups. However, within the first hours after cementation the sensation of pain was considerably higher in the Provicol group than in the Ledermix group.

  1. Human embryonic stem cell-encapsulation in alginate microbeads in macroporous calcium phosphate cement for bone tissue engineering

    Science.gov (United States)

    Tang, Minghui; Chen, Wenchuan; Weir, Michael D.; Thein-Han, Wahwah; Xu, Hockin H. K.

    2012-01-01

    Human embryonic stem cells (hESCs) are exciting for regenerative medicine applications because of their strong proliferative ability and multilineage differentiation capability. To date there has been no report on hESC seeding with calcium phosphate cement (CPC). The objective of this study was to investigate hESC-derived mesenchymal stem cell (hESCd-MSC) encapsulation in hydrogel microbeads in macroporous CPC for bone tissue engineering. hESCs were cultured to form embryoid bodies (EBs), and the MSCs were then migrated out of the EBs. hESCd-MSCs had surface markers characteristic of MSCs, with positive alkaline phosphatase (ALP) staining when cultured in osteogenic medium. hESCd-MSCs were encapsulated in alginate at a density of 1 million cells/mL, with an average microbead size of 207 µm. CPC contained mannitol porogen to create a porosity of 64% and macropores with size of 218 µm, with 20% absorbable fibers for additional porosity when the fibers degrade. hESCd-MSCs encapsulated in microbeads in CPC had good viability from 1 to 21 d. ALP gene expression at 21 d was 25-fold that at 1 d. Osteocalcin (OC) at 21 d was two orders of magnitude of that at 1 d. ALP activity in colorimetric p-nitrophenyl phosphate assay at 21 d was 5-fold that at 1 d. Mineral synthesis by the encapsulated hESCd-MSCs at 21 d was 7-fold that at 1 d. Potential benefits of the CPC-stem cell paste include injectability, intimate adaptation to complex-shaped bone defects, ease in contouring to achieve esthetics in maxillofacial repairs, and in situ setting ability. In conclusion, hESCd-MSCs were encapsulated in alginate microbeads in macroporous CPC showing good cell viability, osteogenic differentiation and mineral synthesis for the first time. The hESCd-MSC-encapsulating macroporous CPC construct is promising for bone regeneration in a wide range of orthopedic and maxillofacial applications. PMID:22633970

  2. [Preliminary application of injectable calcium phosphate cement/poly (lactic-co-glycolic acid) microspheres for extraction site preservation].

    Science.gov (United States)

    Mai, Yuying; Wu, Huihuang; Mai, Zhisong; Li, Xinghong; Huang, Linhui; Liao, Hongbing

    2014-03-01

    To investigate the feasibility of extraction site preservation using injectable calcium phosphate cement (CPC) combine with poly (lactic-co-glycolic acid) (PLGA) microspheres. Immediate extraction defects models were created in canine mandibles, and the defects were filled with CPC/PLGA (experimental group, E) , Bio-Oss (positive control, P), non-treatment (blank control, B) respectively. Dogs were sacrificed after 4, 8, 12 weeks post operation. Statistical analysis were conducted using SPSS 19. of radiological observation showed that there were not significantly different between groups in 4 and 8 week (P > 0.05). After 12 week,E (114.9 ± 8.4) were not significantly different compared with P (117.4 ± 12.1) (P > 0.05) , both were significantly higher than B (95.0 ± 12.6) (P B[(78.7 ± 2.7)%] > E[(69.2 ± 1.8)%] (P < 0.05). At 8, 12 week, results of P[(94.0 ± 2.3)% and (93.5 ± 1.9) %] and E[ (94.7 ± 1.1) % and (96.0 ± 0.9) %] were better than those of B[ (76.8 ± 3.0)% and (87.0 ± 2.4)%] (P < 0.05). The effect of CPC/PLGA repair immediate alveolar ridge defects is the same as that of Bio-Oss, and CPC/PLGA can be used as a material in extraction site preservation.

  3. Comparison of shear bond strength of calcium-enriched mixture cement and mineral trioxide aggregate to composite resin.

    Science.gov (United States)

    Oskoee, Siavash Savadi; Kimyai, Soodabeh; Bahari, Mahmoud; Motahari, Paria; Eghbal, Mohammad Jafar; Asgary, Saeed

    2011-11-01

    Adhesion of composite resin and pulp capping biomaterials remarkably influences treatment outcomes. This in vitro study aimed to compare the shear bond strength of composite resin to calcium enriched mixture (CEM) cement, mineral trioxide aggregate (MTA) and resin modified glass ionomer (RMGI) with or without acid etching. A total of 90 cylindrical acrylic blocks containing a central hole, measuring 4 mm diameter and 2 mm height were prepared. The blocks were randomly divided into three experimental groups based on being filled with CEM, MTA or RMGI. Samples in each group were then randomly divided into two subgroups, i.e. with or without phosphoric acid etching. Placing composite resin cylinders on the samples, shear bond strengths were measured using a universal testing machine. Failure modes of the samples were evaluated under a stereomicroscope. Data were analyzed using two-way ANOVA and Tukey tests. Shear bond strengths in the etched and nonetched samples were not significantly different (p = 0.60). There was a significant difference in shear bond strength values of the three experimental materials (p strength values (p material and surface etching was statistically significant (p shear bond strength of these materials to composite resin. Besides, shear bond strength values of MTA and CEM to composite resin, are favorable due to their cohesive mode of failure. When MTA and CEM biomaterials are used in vital pulp therapy, it is advisable to cover these materials with RMGI. In addition, if it is not possible to use RMGI, the surface etching of MTA and CEM biomaterials is not necessary prior to composite restoration using total-etch adhesive resin.

  4. Casein Phosphopeptide-Amorphous Calcium Phosphate Reduces Streptococcus mutans Biofilm Development on Glass Ionomer Cement and Disrupts Established Biofilms.

    Science.gov (United States)

    Dashper, Stuart G; Catmull, Deanne V; Liu, Sze-Wei; Myroforidis, Helen; Zalizniak, Ilya; Palamara, Joseph E A; Huq, N Laila; Reynolds, Eric C

    2016-01-01

    Glass ionomer cements (GIC) are dental restorative materials that are suitable for modification to help prevent dental plaque (biofilm) formation. The aim of this study was to determine the effects of incorporating casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) into a GIC on the colonisation and establishment of Streptococcus mutans biofilms and the effects of aqueous CPP-ACP on established S mutans biofilms. S. mutans biofilms were either established in flow cells before a single ten min exposure to 1% w/v CPP-ACP treatment or cultured in static wells or flow cells with either GIC or GIC containing 3% w/w CPP-ACP as the substratum. The biofilms were then visualised using confocal laser scanning microscopy after BacLight LIVE/DEAD staining. A significant decrease in biovolume and average thickness of S. mutans biofilms was observed in both static and flow cell assays when 3% CPP-ACP was incorporated into the GIC substratum. A single ten min treatment with aqueous 1% CPP-ACP resulted in a 58% decrease in biofilm biomass and thickness of established S. mutans biofilms grown in a flow cell. The treatment also significantly altered the structure of these biofilms compared with controls. The incorporation of 3% CPP-ACP into GIC significantly reduced S. mutans biofilm development indicating another potential anticariogenic mechanism of this material. Additionally aqueous CPP-ACP disrupted established S. mutans biofilms. The use of CPP-ACP containing GIC combined with regular CPP-ACP treatment may lower S. mutans challenge.

  5. Casein Phosphopeptide-Amorphous Calcium Phosphate Reduces Streptococcus mutans Biofilm Development on Glass Ionomer Cement and Disrupts Established Biofilms.

    Directory of Open Access Journals (Sweden)

    Stuart G Dashper

    Full Text Available Glass ionomer cements (GIC are dental restorative materials that are suitable for modification to help prevent dental plaque (biofilm formation. The aim of this study was to determine the effects of incorporating casein phosphopeptide-amorphous calcium phosphate (CPP-ACP into a GIC on the colonisation and establishment of Streptococcus mutans biofilms and the effects of aqueous CPP-ACP on established S mutans biofilms. S. mutans biofilms were either established in flow cells before a single ten min exposure to 1% w/v CPP-ACP treatment or cultured in static wells or flow cells with either GIC or GIC containing 3% w/w CPP-ACP as the substratum. The biofilms were then visualised using confocal laser scanning microscopy after BacLight LIVE/DEAD staining. A significant decrease in biovolume and average thickness of S. mutans biofilms was observed in both static and flow cell assays when 3% CPP-ACP was incorporated into the GIC substratum. A single ten min treatment with aqueous 1% CPP-ACP resulted in a 58% decrease in biofilm biomass and thickness of established S. mutans biofilms grown in a flow cell. The treatment also significantly altered the structure of these biofilms compared with controls. The incorporation of 3% CPP-ACP into GIC significantly reduced S. mutans biofilm development indicating another potential anticariogenic mechanism of this material. Additionally aqueous CPP-ACP disrupted established S. mutans biofilms. The use of CPP-ACP containing GIC combined with regular CPP-ACP treatment may lower S. mutans challenge.

  6. Environmental scanning electron microscopy connected with energy dispersive x-ray analysis and Raman techniques to study ProRoot mineral trioxide aggregate and calcium silicate cements in wet conditions and in real time.

    Science.gov (United States)

    Gandolfi, Maria Giovanna; Van Landuyt, Kirsten; Taddei, Paola; Modena, Enrico; Van Meerbeek, Bart; Prati, Carlo

    2010-05-01

    ProRoot mineral trioxide aggregate (MTA) and calcium silicate cements are able to set in a moist environment. The aim of the study was to examine the surface structure and composition of a cement paste under wet conditions and in real time during setting by environmental scanning electron microscopy connected with energy dispersive x-ray analysis (ESEM-EDX) and micro-Raman techniques. White ProRoot MTA and experimental white tetrasilicate cement (wTC) and wTC containing bismuth oxide (wTC-Bi) were studied. Cement disks were analyzed 10 minutes after powder-liquid mixing (freshly prepared samples) and after immersion in Dulbecco phosphate-buffered saline at 37 degrees C for 24 hours (24-hour-aged samples). Freshly prepared wet cements at ESEM-EDX exposed an irregular surface (displaying calcium, silicon, aluminum, chlorine reflexes, and bismuth traces in MTA and wTC-Bi) with needle-like and cubic-hexagonal shaped crystals. Aggregates of spheroidal Ca-P-rich crystals (spherulites) appeared on the surface of 24-hour-aged samples. The starting unhydrated powders displayed the typical Raman bands of Portland cement components: alite, belite, and calcium sulfate (only as anhydrite in MTA and as both anhydrite and gypsum in wTC and wTC-Bi). MTA powder showed higher amount of calcium carbonate and lower quantities of anhydrite and higher crystallinity of the silicate component, leading to a slower hydration reaction. Products/markers of hydration reactions were present on fresh samples; ettringite formed on the surface of all the cements; calcium hydroxide (portlandite) was detected only on the surface of wTC, but no conclusion can be drawn on wTC-Bi and MTA because of the interference of bismuth oxide. Calcium phosphate and calcite/aragonite bands were detected on all 24-hour-aged cements; portlandite was no longer detected on wTC. ESEM and micro-Raman are powerful and suitable techniques to investigate endodontic calcium silicate hydrated cements in real time and in

  7. Evaluation of bioactivity in vitro of endodontic calcium aluminate cement; Avaliacao da bioatividade in vitro de cimento endodontico a base de aluminato de calcio

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, I.R.; Andrade, T.L.; Santos, G.L., E-mail: ivonero@univap.br [Universidade do Vale do Paraiba (UNIVAP), Sao Jose dos Campos, SP (Brazil); Pandolfelli, V.C. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil)

    2011-07-01

    Bioactivity is referred to as the capacity of a material to develop a stable bond with living tissue via the deposition of hydroxyapatite. Materials which exhibit this property can be used to repair diseased or damaged bone tissue and can be designed to remain in situ indefinitely. An indication of bioactivity can be obtained by the formation of a hydroxyapatite layer on the surface of a substrate in simulated body fluids (SBF) in vitro. Therefore, set samples of calcium aluminate endodontic cement were maintained in contact with SBF solutions (Kokubo and Rigo) and their surfaces were later evaluated by means of SEM, EDX and DRX. Measurements of pH and ionic conductivity were also carried out for SBF solutions in contact with set samples of endodontic cement. The ideal conditions of precipitation were obtained in SBF Rigo been observed a surface layer with spherical morphology characteristic of stoichiometric hydroxyapatite.(author)

  8. Calcium carbonate precipitation by strain Bacillus licheniformis AK01, newly isolated from loamy soil: a promising alternative for sealing cement-based materials.

    Science.gov (United States)

    Vahabi, Ali; Ramezanianpour, Ali Akbar; Sharafi, Hakimeh; Zahiri, Hossein Shahbani; Vali, Hojatollah; Noghabi, Kambiz Akbari

    2015-01-01

    The relevant experiments were designed to determine the ability of indigenous bacterial strains isolated from limestone caves, mineral springs, and loamy soils to induce calcium carbonate precipitation. Among all isolates examined in this study, an efficient carbonate-precipitating soil bacterium was selected from among the isolates and identified by 16S rRNA gene sequences as Bacillus licheniformis AK01. The ureolytic isolate was able to grow well on alkaline carbonate-precipitation medium and precipitate calcium carbonate more than 1 g L(-1). Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analyses, and scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDX) examinations were performed in order to confirm the presence of calcium carbonate in the precipitate and to determine which polymorphs were present. The selected isolate was determined to be an appropriate candidate for application in a surface treatment of cement-based material to improve the properties of the mortar. Biodeposition of a layer of calcite on the surface of cement specimens resulted in filling in pore spaces. This could be an alternative method to improve the durability of the mortar. The kind of bacterial culture and medium composition had a profound impact on the resultant CaCO(3) crystal morphology. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Effect of Biomineralization Ability on Push-out Strength of Proroot Mineral Trioxide Aggregate, Mineral Trioxide Aggregate Branco, and Calcium Phosphate Cement on Dentin: An In vitro Evaluation.

    Science.gov (United States)

    Revankar, Vanita D; Prathap, M S; Shetty, K Harish Kumar; Shahul, Azmin; Sahana, K

    2017-11-01

    Biomineralization is a process which leads to the formation of an interfacial layer with tag-like structures at the cement-dentin interface. It is due to interaction of mineral trioxide aggregate (MTA) and Portland cement with dentin in phosphate-buffered solution (PBS). This study is aimed to evaluate the effect of influence of biomineralization process on push-out bond strength of ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK, USA), MTA Branco (Angelus Soluc¸o˜es Odontolo´gicas, Londrina, PR, Brazil) and calcium phosphate cement (BioGraft CPC). The aim of this study was to evaluate the effect of biomineralization process on the push-out strength of ProRoot MTA, MTA Branco, and CPC after mixing with 0.2% chlorhexidine gluconate solution (0.2% CHX) and 2% lidocaine solution (2% LA) on the bond strength of MTA-dentin. Dentin discs with uniform cavities were restored with ProRoot MTA, MTA Branco, and calcium phosphate cement after mixing with 0.2% CHX solution and 2% lidocaine solution. The samples were uniformly distributed into two groups. Experimental group being immersed in PBS solution and control group being immersed in saline for 2 months. Instron testing machine (Model 4444; Instron Corp., Canton, MA, USA) was used to determine the bond strength. A two-way analysis of variance and post hoc analysis by Bonferroni test. All samples immersed in experimental group displayed a significantly greater resistance to displacement than that observed for the samples in control group (P MTA groups, was positively influenced by the biomineralization process.

  10. [Preparation and ectopic osteoinduction study of macroporous bone substitute with calcium phosphate cements and rhBMP-2 loaded gelatin microspheres].

    Science.gov (United States)

    Li, Meng; Liu, Xu-dong; Liu, Xing-yan; Ge, Bao-feng

    2011-05-01

    To prepare macroporous bone substitute composed of calcium phosphate cements and rhBMP-2 loaded gelatin microspheres, and to investigate ectopic osteoinduction of the composite. After being prepared by improved emulsified cold-condensation method and crosslinked by 5% genipin solution,gelatin microspheres (GMs) were observed by scanning electron microscope (SEM) and loaded with rhBMP-2 by adsorption. Macroporous bone substitute was developed by mixing calcium phosphate cement (CPC) with 2.5% GMs, being as the experimental group,and CPC with rhBMP-2 was the control group. After the both composites had been soaked in the sodium chloride for 1 week or 3 weeks, compressive strength of the composites were tested, and the cross-sections were observed by SEM. Concentrations of rhBMP-2 in the solutions at different time by ELISA method and the cumulative drug release amount was calculated. The composites had been implanted in the muscle bags of the mouses for 3 weeks. Then the tissues around the materials were collected, stained by hematoxylin and eosin, and Ca and ALP in the tissues were also measured. Gelatin microspheres were spherical with diameters of (62 +/- 18) microm. Macropores appeared in the experimental materials 1 week and 3 weeks after being soaked,and total porosity, macroporosity, cumulative release amount of rhBMP-2 in the experimental group were higher than that in the control. But compressive strength of the experimental group was lower than that of the control group 3 weeks after being soaked. Results of HE stain showed chondral formation in both groups, but there were more chondral tissues in the experiment group, and so were the concentrations of Ca and ALP. Macroporous calcium phosphate cement can be prepared by using rhBMP-2 loaded gelatin microspheres, and it is an excellent bone substitute due to it's proterty of promoting rhBMP release and powerful ectopic osteoinduction.

  11. Strontium exerts dual effects on calcium phosphate cement: Accelerating the degradation and enhancing the osteoconductivity both in vitro and in vivo.

    Science.gov (United States)

    Kuang, Guan-Ming; Yau, W P; Wu, Jun; Yeung, Kelvin W K; Pan, Haobo; Lam, W M; Lu, W W; Chiu, K Y

    2015-05-01

    Calcium phosphate cements (CPCs) have long been used as osteoconductive bone substitutes in the treatment of bone defects. However, the degradation rate of CPC is typically too slow to match the new bone growth rate. It is known that strontium increases the solubility of hydroxyapatite as well as exerts both anabolic and anticatabolic effects on bone. Therefore, we hypothesized that the incorporation of strontium would accelerate the degradation rate and enhance the osteoconductivity of CPC. In this study, Three groups, CPC (0% Sr-CPC), 5% Sr-CPC, and 10% Sr-CPC, were prepared, with the total molar ratio for Sr/(Sr+Ca) in the cement powder phase being 0, 5, and 10%, respectively. In the immersion test, less residual weight was observed in both 5% Sr-CPC and 10% Sr-CPC groups than CPC group. In addition, a higher osteoblastic cell proliferation rate and alkaline phosphatase activity were obtained in the strontium groups. In a rat femur bone defect model comparing CPC with 10% Sr-CPC, at 2 weeks postoperation, early endochondral ossification was found in the 10% Sr-CPC group, whereas only fibrous tissue was observed in control group; at 4-16 weeks postoperation, progressive osteoconduction toward the cement was observed in both groups. At 32 weeks, a higher peri-cement bone area and reduced cement area were noted in the 10% Sr-CPC group. In conclusion, in the 10% Sr-CPC group, strontium exerts dual effects on CPC: accelerating degradation rate and enhancing osteoconductivity, as shown here both in vitro and in vivo. © 2014 Wiley Periodicals, Inc.

  12. A in-vitro comparative study on bacterial leakage of mineral trioxide aggregate, calcium enriched cement and bone cement in furcal perforations.

    Science.gov (United States)

    Nazari Moghadam, K; Aghili, H; Rashed Mohasel, A; Zahedpasha, S; Moghadamnia, A A

    2014-07-08

    The aim of this study was to compare the bacterial leakage of mineral trioxide aggregate (MTA), calciem enriched cement (CEM), and bone cement (BC) as repair materials in furcal perforations. The pulp chambers of 57 human mandibular molar teeth were accessed and the root canal orifices were located. The roots were horizontally sectioned in the middle third. Composite resin was used to fill the root canal orifices and the apical end of the roots. The 1mm furcation perforations were performed in the center of the pulp chamber floor, using diamond fissure burs. Fifty one teeth were divided into 3 groups. Six teeth were used as controls.Perforation defects were repaired with either MTA, CEM, or BC. A bacterial leakage model utilizing phenol red with 3% lactose broth was used for evaluation. The upper pulp chambers were subsequently filled with 5μL bacterial suspension containing Enterococcus faecalis. Then the top of the assembly was covered with aluminum foil to avoid unintentional contamination. The entire apparatus was incubated at 37°C, and bacterial leakage was evaluated daily by checking the turbidity in the culture medium of the lower part of the chamber. The bacterial inoculation was renewed every day, for 30 days. Leakage was noted when color conversion of the culture media was observed and was statistically analyzed using the Chi--square test with significance set at P 0.05). According to the present study, in teeth with furcation perforations, the coronal seal produced by MTA preparations was equally to that produced by CEM cement and Bone cement.

  13. Human embryonic stem cell encapsulation in alginate microbeads in macroporous calcium phosphate cement for bone tissue engineering.

    Science.gov (United States)

    Tang, M; Chen, W; Weir, M D; Thein-Han, W; Xu, H H K

    2012-09-01

    Human embryonic stem cells (hESC) are promising for use in regenerative medicine applications because of their strong proliferative ability and multilineage differentiation capability. To date there have been no reports on hESC seeding with calcium phosphate cement (CPC). The objective of this study was to investigate hESC-derived mesenchymal stem cell (hESCd-MSC) encapsulation in hydrogel microbeads in macroporous CPC for bone tissue engineering. hESC were cultured to form embryoid bodies (EB), and the MSC were then migrated out of the EB. hESCd-MSC had surface markers characteristic of MSC, with positive alkaline phosphatase (ALP) staining when cultured in osteogenic medium. hESCd-MSC were encapsulated in alginate at a density of 1millioncellsml(-1), with an average microbead size of 207μm. CPC contained mannitol porogen to create a porosity of 64% and 218-μm macropores, with 20% absorbable fibers for additional porosity when the fibers degrade. hESCd-MSC encapsulated in microbeads in CPC had good viability from 1 to 21days. ALP gene expression at 21days was 25-fold that at 1day. Osteocalcin (OC) at 21days was two orders of magnitude of that at 1day. ALP activity in colorimetric p-nitrophenyl phosphate assay at 21days was fivefold that at 1day. Mineral synthesis by the encapsulated hESCd-MSC at 21days was sevenfold that at 1day. Potential benefits of the CPC-stem cell paste include injectability, intimate adaptation to complex-shaped bone defects, ease in contouring to achieve esthetics in maxillofacial repairs, and in situ setting ability. In conclusion, hESCd-MSC were encapsulated in alginate microbeads in macroporous CPC, showing good cell viability, osteogenic differentiation and mineral synthesis for the first time. The hESCd-MSC-encapsulating macroporous CPC construct is promising for bone regeneration in a wide range of orthopedic and maxillofacial applications. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  14. Substitutions in Calcium Aluminates and Calcium Aluminoferrites.

    Science.gov (United States)

    ALUMINUM COMPOUNDS, *CEMENTS, * CALCIUM COMPOUNDS, * FERRITES , *SCIENTIFIC RESEARCH, INFRARED SPECTROSCOPY, X RAY DIFFRACTION, CHEMICAL COMPOSITION, SUBSTITUTES, CHEMICAL ANALYSIS, ALKALI METAL COMPOUNDS.

  15. Comparison of push-out bond strength of mineral trioxide aggregate and calcium enriched mixture cement as root end filling materials

    Directory of Open Access Journals (Sweden)

    Alireza Adl

    2014-01-01

    Full Text Available Background: The purpose of this study was to compare the push-out bond strength of mineral trioxide aggregate (MTA and calcium enriched mixture (CEM as root end filling materials. Materials and Methods: A total of 40 root dentin slices (1 ± 0.2 mm were prepared from freshly extracted human maxillary central teeth and their lumens were enlarged to 1.3 mm. The slices were randomly divided into two groups (n = 20. MTA and CEM cement were mixed according to manufacturer′s instruction and introduced into the lumens. The specimens were wrapped in pieces of wet gauze soaked in distilled water and incubated at 37°C for 3 days. The push-out bond strength was measured using a universal testing machine. The slices were then examined under a light microscope at ×10 magnification to determine the nature of bond failure. The data were analyzed using Mann-Whitney test (P < 0.001. Results: The mean push-out bond strength for CEM cement and MTA were 1.68 ± 0.9 and 5.94 ± 3.99 respectively. The difference was statistically significant (P < 0.001. The bond failure was predominantly of adhesive type in MTA group and cohesive type in CEM group. Conclusion: CEM cement showed significantly lower bond strength to the dentinal wall compared to MTA.

  16. Photocatalytic NO{sub x} abatement by calcium aluminate cements modified with TiO{sub 2}: Improved NO{sub 2} conversion

    Energy Technology Data Exchange (ETDEWEB)

    Pérez-Nicolás, M. [MIMED Research Group, Department of Chemistry and Soil Sciences, School of Sciences, University of Navarra, c/Irunlarrea, 1, 31008 Pamplona (Spain); Balbuena, J.; Cruz-Yusta, M.; Sánchez, L. [Department of Inorganic Chemistry, School of Sciences, University of Córdoba, Campus de Rabanales, Edificio Marie Curie, 14071 Córdoba (Spain); Navarro-Blasco, I.; Fernández, J.M. [MIMED Research Group, Department of Chemistry and Soil Sciences, School of Sciences, University of Navarra, c/Irunlarrea, 1, 31008 Pamplona (Spain); Alvarez, J.I., E-mail: jalvarez@unav.es [MIMED Research Group, Department of Chemistry and Soil Sciences, School of Sciences, University of Navarra, c/Irunlarrea, 1, 31008 Pamplona (Spain)

    2015-04-15

    Photocatalytic activity of TiO{sub 2} was studied in two types of calcium aluminate cement (CAC) under two different curing regimes. The effect of the TiO{sub 2} addition on the setting time, consistency and mechanical properties of the CACs was evaluated. The abatement of gaseous pollutants (NO{sub x}) under UV irradiation was also assessed. These cementitious matrices were found to successfully retain NO{sub 2}: more abundant presence of aluminates in white cement (w-CAC, iron-lean) helped to better adsorb NO{sub 2}, thus improving the conversion performance of the catalyst resulting in a larger NO{sub x} removal under UV irradiation. As evidenced by XRD, SEM, EDAX and zeta potential analyses, the presence of ferrite in dark cement (d-CAC, iron-reach) induced a certain chemical interaction with TiO{sub 2}. The experimental findings suggest the formation of new iron titanate phases, namely pseudobrookite. The reduced band-gap energy of these compounds compared with that of TiO{sub 2} accounts for the photocatalytic activity of these samples.

  17. Acceleration of bone regeneration by activating Wnt/β-catenin signalling pathway via lithium released from lithium chloride/calcium phosphate cement in osteoporosis

    Science.gov (United States)

    Li, Li; Peng, Xiaozhong; Qin, Yongbao; Wang, Renchong; Tang, Jingli; Cui, Xu; Wang, Ting; Liu, Wenlong; Pan, Haobo; Li, Bing

    2017-03-01

    By virtue of its excellent bioactivity and osteoconductivity, calcium phosphate cement (CPC) has been applied extensively in bone engineering. Doping a trace element into CPC can change physical characteristics and enhance osteogenesis. The trace element lithium has been demonstrated to stimulate the proliferation and differentiation of osteoblasts. We investigated the fracture-healing effect of osteoporotic defects with lithium-doped calcium phosphate cement (Li/CPC) and the underlying mechanism. Li/CPC bodies immersed in simulated body fluid converted gradually to hydroxyapatite. Li/CPC extracts stimulated the proliferation and differentiation of osteoblasts upon release of lithium ions (Li+) at 25.35 ± 0.12 to 50.74 ± 0.13 mg/l through activation of the Wnt/β-catenin pathway in vitro. We also examined the effect of locally administered Li+ on defects in rat tibia between CPC and Li/CPC in vivo. Micro-computed tomography and histological staining showed that Li/CPC had better osteogenesis by increasing bone mass and promoting repair in defects compared with CPC (P osteoporosis.

  18. Synthesized mesoporous silica and calcium aluminate cement fillers increased the fluoride recharge and lactic acid neutralizing ability of a resin-based pit and fissure sealant.

    Science.gov (United States)

    Surintanasarn, Atikom; Siralertmukul, Krisana; Thamrongananskul, Niyom

    2017-11-29

    This study evaluated the effect of different types of filler in a resin-based pit and fissure sealant on fluoride release, recharge, and lactic acid neutralization. Resin-based sealant was incorporated with 5% w/w of the following fillers: calcium aluminate cement (CAC), synthesized mesoporous silica (SI), a CAC and SI mixture (CAC+SI), glass-ionomer powder (GIC), and acetic acid-treated GIC (GICA). Sealant without filler served as control. The samples were immersed in deionized water or a lactic acid solution and the concentration of fluoride in the water, before and after fluoride recharge, and the lactic acid pH change, respectively, were determined. The CAC+SI group demonstrated the highest fluoride release after being recharged with fluoride gel. The CAC+SI group also demonstrated increased lactic acid pH. These findings suggest that a resin-based sealant containing synthesized mesoporous silica and calcium aluminate cement may enhance remineralization due to fluoride release and higher pH.

  19. Co-grinding significance for calcium carbonate-calcium phosphate mixed cement. Part I: effect of particle size and mixing on solid phase reactivity.

    Science.gov (United States)

    Tadier, S; Le Bolay, N; Rey, C; Combes, C

    2011-04-01

    In part I of this study we aim to evaluate and control the characteristics of the powders constituting the solid phase of a vaterite CaCO(3)-dicalcium phosphate dihydrate cement using a co-grinding process and to determine their impact on cement setting ability. An original methodology involving complementary analytical techniques was implemented to thoroughly investigate the grinding mechanism of separated or mixed reactive powders and the effects on solid phase reactivity. We showed that the association of both reactive powders during co-grinding improves the efficiency of this process in terms of the particle size decrease, thus making co-grinding adaptable to industrial development of the cement. For the first time the usefulness of horizontal attenuated total reflection Fourier transform infrared spectroscopy to follow the chemical setting reaction at 37°C in real time has been demonstrated. We point out the antagonist effects that co-grinding can have on cement setting: the setting time is halved; however, progress of the chemical reaction involving dissolution-reprecipitation is delayed by 30 min, probably due to the increased contact area between the reactive powders, limiting their hydration. More generally, we can take advantage of the co-grinding process to control powder mixing, size and reactivity and this original analytical methodology to better understand its effect on the phenomena involved during powder processing and cement setting, which is decisive for the development of multi-component cements. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  20. Calcium

    Science.gov (United States)

    ... and blood vessels contract and expand, to secrete hormones and enzymes and to send messages through the nervous system. It is important to get plenty of calcium in the foods you eat. Foods rich in calcium include Dairy products such as milk, cheese, and yogurt Leafy, green vegetables Fish with ...

  1. Modeling the influence of limestone addition on cement hydration

    Directory of Open Access Journals (Sweden)

    Ashraf Ragab Mohamed

    2015-03-01

    Full Text Available This paper addresses the influence of using Portland limestone cement “PLC” on cement hydration by characterization of its microstructure development. The European Standard EN 197-1:2011 and Egyptian specification ESS 4756-1/2009 permit the cement to contain up to 20% ground limestone. The computational tools assist in better understanding the influence of limestone additions on cement hydration and microstructure development to facilitate the acceptance of these more economical and ecological materials. μic model has been developed to enable the modeling of microstructural evolution of cementitious materials. In this research μic model is used to simulate both the influence of limestone as fine filler, providing additional surfaces for the nucleation and growth of hydration products. Limestone powder also reacts relatively slow with hydrating cement to form monocarboaluminate (AFmc phase, similar to the mono-sulfoaluminate (AFm phase formed in ordinary Portland cement. The model results reveal that limestone cement has accelerated cement hydration rate, previous experimental results and computer model “cemhyd3d” are used to validate this model.

  2. Studies on the Effect of Rice Husk Ash as Cement Admixture * M.U ...

    African Journals Online (AJOL)

    acer

    compact whole (Neville, 1996). Cements are classified as calcium silicate and calcium aluminate cement. Calcium silicate cement is further classified into Portland and Slag, while calcium aluminate is classified into High alumina and Pozzolona cement (Jackson and Dhir, 1991). Rice husk has recently been recognized as.

  3. Evaluation of the mechanical properties of conventional glass ionomer cement after the addition of casein phosphopeptide amorphous calcium phosphate: An in vitro study

    Directory of Open Access Journals (Sweden)

    Shalini Aggarwal

    2014-01-01

    Full Text Available Background: Casein phosphopeptides-amorphous calcium phosphate (CPP-ACP products have gained much importance in restorative dentistry and minimally invasive dentistry. Addition of CPP into glass ionomer cement (GIC has been shown to interact with fluoride ions to produce an additive anticariogenic effect through the formation of stabilized amorphous calcium fluoride phosphate phase. Aim: The aim of this study was to determine the additive effect of CPP-ACP on the mechanical properties of conventional GIC. Materials and Methods: The control GIC was prepared with self-curing GIC. The GIC containing CPP-ACP was prepared from the same batch, with 1.56% w/w CPP-ACP incorporated. Compressive strength and microtensile bond strength tests were done. Energy dispersive X-ray (EDX analysis was used to determine the composition of various structural phases. Results: Incorporation of 1.56% w/w CPP-ACP into the GIC resulted in an increase in compressive strength and microtensile bond strength. The representative EDX spectra taken showed enhanced release of calcium, phosphate, and fluoride ions.

  4. Calcium

    Science.gov (United States)

    ... from dietary supplements are linked to a greater risk of kidney stones, especially among older adults. But calcium from foods does not appear to cause kidney stones. For most people, other factors (such as not drinking enough fluids) probably have ...

  5. Propriedades e bioatividade de um cimento endodôntico à base de aluminato de cálcio Properties and bioactivity of endodontic calcium aluminate cement

    Directory of Open Access Journals (Sweden)

    I. R. Oliveira

    2011-09-01

    Full Text Available Desde sua introdução na endodontia como um material retro-obturador e selador de defeitos da raiz dental, o agregado de trióxido mineral (MTA tem sido considerado como um material endodôntico revolucionário. Apesar disso, este material apresenta algumas propriedades limitantes, necessitando alterações em sua composição bem como desenvolvimento de novos materiais. Assim, o objetivo desse trabalho foi mostrar a influência de aditivos no desenvolvimento de um cimento endodôntico à base de cimento de aluminato de cálcio (ECAC. Além disso, foram avaliadas as propriedades do ECAC em comparação com o MTA, quando em contato com solução de fluido corporal simulado (SBF. Testes de manipulação e medidas de resistência à compressão, porosidade aparente, tempo de endurecimento, pH e condutividade iônica, foram realizados para os materiais MTA puro e ECAC contendo aditivos. Considerando as propriedades apresentadas pelo ECAC, este material alternativo pode ser indicado para múltiplas aplicações em endodontia.The mineral trioxide aggregate (MTA, a material primarily developed as a root-end filling has been extensively investigated as an innovative product for endodontic applications. However, changes in its formulation/composition involving its mineral aggregates and the development of alternatives of materials have been proposed in an attempt to overcome its negative physical-chemical characteristics. In this work, the influence of additives addition on the development of a novel endodontic cement based on calcium aluminate, has been evaluated. In addition, the properties of endodontic calcium aluminate cement (ECAC were compared with the gold standard mineral-trioxide-aggregate in contact with simulated body fluid (SBF. Manipulation tests and measurements of compressive strength, apparent porosity, setting time, pH and ionic conductivity were carried out on plain MTA and calcium aluminate cement with and without various additives

  6. Study of the ultrasonic waves action on the preparation of calcium aluminates cements; Estudo da acao das ondas ultrasonicas na sintese de cimentos de aluminatos de calcio

    Energy Technology Data Exchange (ETDEWEB)

    Lourenco, R.R.; Exposito, C.C.D.; Rodrigues, J.A., E-mail: josear@ufscar.b [Universidade Federal de Sao Carlos (DEMa/GEMM/UFScar), SP (Brazil). Dept. de Engenharia de Materiais. Grupo de Engenharia de Microestrutura de Materiais

    2009-07-01

    Calcium aluminates cements were prepared through a route that uses the sonochemical process. In this process, calcia and alumina in an aqueous suspension are put under an ultrasonic bath during some time. After that, the water is evaporated and the material is heat treated. In this work, the action of ultrasonic waves were studied on initials molar compositions calcia:alumina of 1:1. It was also verified the influence of the water on the reactivity of initial solids. SEM and X-ray diffraction were used to characterize the obtained materials. In addition, mechanical strength of the products was evaluated through splitting tensile tests. The X-ray diffractograms showed that the presence of the water was enough to form hydrated compounds. However the material subjected to the sonochemical process presented the highest mechanical strength, indicating the potential of this route of synthesis. (author)

  7. The role of integrin αv in proliferation and differentiation of human dental pulp cell response to calcium silicate cement.

    Science.gov (United States)

    Hung, Chi-Jr; Hsu, Hsin-I; Lin, Chi-Chang; Huang, Tsui-Hsien; Wu, Buor-Chang; Kao, Chia-Tze; Shie, Ming-You

    2014-11-01

    It has been proved that integrin αv activity is related to cell proliferation, differentiation, migration, and organ development. However, the biological functions of integrin αv in human dental pulp cells (hDPCs) cultured on silicate-based materials have not been explored. The aim of this study was to investigate the role of integrin αv in the proliferation and odontogenic differentiation of hDPCs cultured with the effect of calcium silicate (CS) cement and β-tricalcium phosphate (TCP) cement. In this study, hDPCs were cultured on CS and TCP materials, and we evaluated fibronectin (FN) secretion and integrin αv expression during the cell attachment stage. After small interfering RNA transfection targeting integrin αv, the proliferation and odontogenesis differentiation behavior of hDPCs were analyzed. The results indicate that CS releases Si ion-increased FN secretion and adsorption, which promote cell attachment more effectively than TCP. The CS cement facilitates FN and αv subintegrin expression. However, the FN adsorption and integrin expression of TCP are similar to that observed in the control dish. Integrin αv small interfering RNA inhibited odontogenic differentiation of hDPCs with the decreased formation of mineralized nodules on CS. It also down-regulated the protein expression of multiple markers of odontogenesis and the expression of dentin sialophosphoprotein protein. These results establish composition-dependent differences in integrin binding and its effectiveness as a mechanism regulating cellular responses to biomaterial surface. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  8. Dehydration kinetics of Portland cement paste at high temperature

    NARCIS (Netherlands)

    Zhang, Q.; Ye, G.

    2012-01-01

    Portland cement paste is a multiphase compound mainly consisting of calcium-silicate-hydrate (CSH) gel, calcium hydroxide (CH) crystal, and unhydrated cement core. When cement paste is exposed to high temperature, the dehydration of cement paste leads to not only the decline in strength, but also

  9. Synthesis optimization of calcium aluminate cement phases for biomedical applications; Avaliacao da sintese das fases de cimento de aluminato de calcio

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, T.L.; Santos, G.L.; Oliveira, I.R. [Universidade do Vale do Paraiba (UNIVAP), Sao Jose dos Campos, SP (Brazil); Pandolfelli, V.C. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil)

    2011-07-01

    Calcium aluminate cement (CAC) has been studied as a potential material for applications in the areas of health such as, endodontics and bone reconstruction. These studies have been based on commercial products consisting of a mixture of phases. Improvements can be attained by investigating the synthesis routes of CAC aiming the proper balance between the phases and the control of impurities that may impair its performance for biomedical applications. Thus, the aim of this work was to study the CAC synthesis routes in the Al{sub 2}O{sub 3}-CaCO{sub 3} and Al{sub 2}O{sub 3}-CaO systems, as well as the phase characterization attained by means of X ray analysis. The Al{sub 2}O{sub 3}-CaO route enabled the production of the target phases (CA, CA{sub 2}, C{sub 3}A and C{sub 12}A{sub 7}) with a higher purity compared to the Al2O3-CaCO3 one. As a result the particular properties of these phases can be evaluated to define a more suitable composition that results in better properties for an endodontic cement and other applications. (author)

  10. Influência de aditivos dispersantes e acelerador na hidratação de cimento e cimento-matriz Influence of dispersant and accelerator additives on hydration of calcium aluminate cement and cement-matrix

    Directory of Open Access Journals (Sweden)

    I. R. Oliveira

    2006-09-01

    Full Text Available A aplicação de concretos refratários, principalmente na siderurgia, é um processo em constante evolução, que apresenta uma forte dependência dos avanços dos conhecimentos sobre os ligantes hidráulicos. Isso se deve a influência exercida por estes ligantes nas propriedades reológicas e desenvolvimento de resistência mecânica de concretos. O processo de hidratação dos ligantes é sensivelmente influenciado pela presença de aditivos, afetando o tempo requerido para efetuar a desmoldagem do corpo conformado. Além disso, a adição de alumina ao cimento também influencia o seu comportamento de hidratação, bem como a extensão do período de indução, a composição das fases e dos produtos de hidratação. Assim, neste trabalho foi estudada a influência da presença de aditivos dispersantes e/ou acelerador no processo de hidratação de cimento e cimento-matriz. Independente do sistema, os aditivos dispersantes atuaram como retardadores do processo de hidratação, principalmente para o caso do ácido cítrico e citrato de diamônio. Tais aditivos apresentaram-se também como os mais eficientes para a combinação com o acelerador Li2CO3, resultando em um tempo de pega intermediário. Isto mostra ser possível controlar a trabalhabilidade reduzindo o tempo para a desmoldagem.A growing demand for refractory castables with specific behaviors has been promoting a continuous technological evolution, in which, one of the most important aspects concerns in a deep knowledge of hydraulic binders. These materials present a great influence on the rheological properties and mechanical strength development of castables, defining their workability periods and demoulding times, respectively. The hydration process of calcium aluminate cement is influenced by the presence of additives, which affects the setting and demoulding time of the shaped body. Besides that, the alumina addition to cement also influences the hydration behaviour, as well

  11. Local application of strontium in a calcium phosphate cement system accelerates healing of soft tissue tendon grafts in anterior cruciate ligament reconstruction: experiment using a rabbit model.

    Science.gov (United States)

    Kuang, Guan-Ming; Yau, W P; Lu, William W; Chiu, K Y

    2014-12-01

    Healing of soft tissue tendon grafts within the bone tunnel in anterior cruciate ligament (ACL) reconstruction is known to be slower than that of bone-patellar tendon-bone grafts. There are attempts to accelerate healing of the graft within the bone tunnel. One of the methods is the use of strontium-enriched calcium phosphate cement (Sr-CPC). Early results in animal studies have been encouraging, although it is not known whether the accelerated healing was solely caused by the effect of strontium within the cement or by the calcium phosphate cement (CPC) itself. There would be differences between Sr-CPC and conventional CPC in terms of the effect on healing of soft tissue tendon grafts within the bone tunnels in ACL reconstruction. Controlled laboratory study. A total of 30 single-bundle ACL reconstruction procedures were performed in 15 rabbits with the use of an Achilles tendon allograft. The graft on the left limb was coated with Sr-CPC, while that on the right limb was coated with CPC. Three animals each were sacrificed for histological and histomorphometric analyses at 3, 6, 9, 12, and 24 weeks after surgery. In the Sr-CPC group, early formation of Sharpey fibers was present at 6 weeks after surgery, while early remodeling of a graft-fibrocartilage-bone junction was noted at 12 weeks. In the CPC group, early formation of Sharpey fibers was only found at 9 to 12 weeks after surgery. At 24 weeks, a direct enthesis was found in both groups. According to the histomorphometric score, graft healing in the Sr-CPC group took place 3 weeks faster than that in the CPC group at and before 12 weeks; however, there was no difference between the groups at 24 weeks. The local application of strontium in a CPC system leads to accelerated graft healing within the bone tunnels. The use of Sr-CPC to enhance graft-bone healing may improve the clinical results of ACL reconstruction using soft tissue tendon grafts. © 2014 The Author(s).

  12. Regulation of physicochemical properties, osteogenesis activity, and fibroblast growth factor-2 release ability of β-tricalcium phosphate for bone cement by calcium silicate

    Energy Technology Data Exchange (ETDEWEB)

    Su, Ching-Chuan [Antai Medical Care Cooperation Antai Tian-Sheng Memorial Hospital, Pingtung, Taiwan (China); Kao, Chia-Tze; Hung, Chi-Jr [School of Dentistry, Chung Shan Medical University, Taichung, Taiwan (China); Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan (China); Chen, Yi-Jyun [School of Dentistry, Chung Shan Medical University, Taichung, Taiwan (China); Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan (China); Dental Department, Taichung Hospital, Ministry of Health and Welfare, Taichung City, Taiwan (China); Huang, Tsui-Hsien, E-mail: thh@csmu.edu.tw [School of Dentistry, Chung Shan Medical University, Taichung, Taiwan (China); Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan (China); Shie, Ming-You, E-mail: eviltacasi@gmail.com [Institute of Oral Science, Chung Shan Medical University, Taichung, Taiwan (China)

    2014-04-01

    β-Tricalcium phosphate (β-TCP) is an osteoconductive material. For this research we have combined it with a low degradation calcium silicate (CS) to enhance its bioactive and osteostimulative properties. To check its effectiveness, a series of β-TCP/CS composites with different ratios were prepared to make new bioactive and biodegradable biocomposites for bone repair. Formation of bone-like apatite, the diametral tensile strength, and weight loss of composites were considered before and after immersion in simulated body fluid (SBF). In addition, we also examined the effects of fibroblast growth factor-2 (FGF-2) released from β-TCP/CS composites and in vitro human dental pulp cell (hDPC) and studied its behavior. The results showed that the apatite deposition ability of the β-TCP/CS composites was enhanced as the CS content was increased. For composites with more than 50% CS contents, the samples were completely covered by a dense bone-like apatite layer. At the end of the immersion point, weight losses of 19%, 24%, 33%, 42%, and 51% were observed for the composites containing 0%, 30%, 50%, 70% and 100% β-TCP cements, respectively. In vitro cell experiments show that the CS-rich composites promote human dental pulp cell (hDPC) proliferation and differentiation. However, when the CS quantity in the composite is less than 70%, the amount of cells and osteogenesis protein of hDPCs was stimulated by FGF-2 released from β-TCP/CS composites. The combination of FGF-2 in degradation of β-TCP and osteogenesis of CS gives a strong reason to believe that these calcium-based composite cements may prove to be promising bone repair materials. - Highlights: • CS improved physicochemical properties and osteogenic activity of β-TCP. • The higher the CS in the cement, the shorter the setting time and the higher the DTS. • The cell behavior was stimulated by FGF-2 released from composite containing 50% CS. • β-TCP/CS composite with FGF-2 has optimal properties for

  13. Immobilization of calcium sulfate contained in demolition waste

    Energy Technology Data Exchange (ETDEWEB)

    Ambroise, J. [Laboratoire Genie Civil et Ingenierie Environnementale (LGCIE), Institut National des Sciences Appliquees de Lyon, Domaine Scientifique de la Doua, Batiment J. Tuset, 12, Avenue des Arts, 69 621 Villeurbanne Cedex (France); Pera, J. [Laboratoire Genie Civil et Ingenierie Environnementale (LGCIE), Institut National des Sciences Appliquees de Lyon, Domaine Scientifique de la Doua, Batiment J. Tuset, 12, Avenue des Arts, 69 621 Villeurbanne Cedex (France)], E-mail: Jean.Pera@insa-lyon.fr

    2008-03-01

    This paper presents the results of a laboratory study undertaken to examine the treatment of demolition waste containing calcium sulfate by means of calcium sulfoaluminate clinker (CSA). The quantity of CSA necessary to entirely consume calcium sulfate was determined. Using infrared spectrometry analysis and X-ray diffraction, it was shown that calcium sulfate was entirely consumed when the ratio between CSA and calcium sulfate was 4. Standard sand was polluted by 4% calcium sulfate. Two solutions were investigated: {center_dot}either global treatment of sand by CSA, {center_dot}or immobilization of calcium sulfate by CSA, followed by the introduction of this milled mixture in standard sand. Regardless of the type of treatment, swelling was almost stabilized after 28 days of immersion in water.

  14. Mechanistic study and modeling of radionuclides retention by the hydrated calcium silicates (HCS) of cements; Etude mecanistique et modelisation de la retention de radionucleides par les silicates de calcium hydrates (CSH) des ciments

    Energy Technology Data Exchange (ETDEWEB)

    Pointeau, I

    2000-09-01

    This work attempts to investigate the modelling of radioisotopes (Cs{sup +}, Pb{sup 2+}, Eu{sup 3+}) immobilization in cement matrix, in the frame of the design of engineered barrier of a deep radwaste repository. The model development concept consists of three major steps: - surface chemistry modelling of the calcium silicate hydrate CSH, used to simulate hydrated cement behaviour; - solid analysis of the batch sorption experiments: identification of the uptake mechanism; - both previous steps are used, with isotherm data, in the modelling of the radioisotopes immobilization in the CSH matrix. Final results: (all modelling are available for all the range of studied Ca/Si ratios and have been validated with predictive calculations). - A thermodynamic modelling of the CSH surface chemistry has been developed. The labile calcium and proton sorption constants on silanol sites (>SiOH) have been extracted. - Cs{sup +} is sorbed on two sites. The silanol site (weak site) has a high site density (10 sites.nm{sup -2}), which accounts for the CSH unsaturation in high [CS{sup +}]. A strong site is also identified. - Pb{sup 2+} immobilization in CSH matrix is modelled with surface equilibria and solubility equilibrium. - Eu{sup 3+} fixation has been investigated with solid analysis: Site-Selective anti Time-Resolved Luminescence Spectroscopy, XPS and SEM-EDS. Eu{sup 3+} thus does not precipitate in CSH water but is sorbed on the CSH surface (high hydroxylated environment). Europium is also (minority site) inserted in the CSH framework. (author)

  15. Tuning the degradation rate of calcium phosphate cements by incorporating mixtures of polylactic-co-glycolic acid microspheres and glucono-delta-lactone microparticles.

    Science.gov (United States)

    Sariibrahimoglu, Kemal; An, Jie; van Oirschot, Bart A J A; Nijhuis, Arnold W G; Eman, Rhandy M; Alblas, Jacqueline; Wolke, Joop G C; van den Beucken, Jeroen J J P; Leeuwenburgh, Sander C G; Jansen, John A

    2014-11-01

    Calcium phosphate cements (CPCs) are frequently used as synthetic bone graft materials in view of their excellent osteocompatibility and clinical handling behavior. Hydroxyapatite-forming CPCs, however, degrade at very low rates, thereby limiting complete bone regeneration. The current study has investigated whether degradation of apatite-forming cements can be tuned by incorporating acid-producing slow-resorbing poly(D,L-lactic-co-glycolic) acid (PLGA) porogens, fast-resorbing glucono-delta-lactone (GDL) porogens, or mixtures thereof. The physicochemical, mechanical, and degradation characteristics of these CPC formulations were systematically analyzed upon soaking in phosphate-buffered saline (PBS). In parallel, various CPC formulations were implanted intramuscularly and orthotopically on top of the transverse process of goats followed by analysis of the soft tissue response and bone ingrowth after 12 weeks. In vitro degradation of GDL was almost completed after 2 weeks, as evidenced by characterization of the release of gluconic acid, while PLGA-containing CPCs released glycolic acid throughout the entire study (12 weeks), resulting in a decrease in compression strength of CPC. Extensive in vitro degradation of the CPC matrix was observed upon simultaneous incorporation of 30% PLGA-10% GDL. Histomorphometrical evaluation of the intramuscularly implanted samples revealed that all CPCs exhibited degradation, accompanied by an increase in capsule thickness. In the in vivo goat transverse process model, incorporation of 43% PLGA, 30% PLGA-5% GDL, and 30% PLGA-10% GDL in CPC significantly increased bone formation and resulted in higher bone height compared with both 10% GDL and 20% GDL-containing CPC samples.

  16. Study of mechanical properties of calcium phosphate cement with addition of sodium alginate and dispersant; Estudo das propriedades mecanicas de cimento de fosfato de calcio com adicao de alginato de sodio e defloculante

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, J.M.; Coelho, W.T.; Thurmer, M.B.; Vieira, P.S.; Santos, L.A., E-mail: julianafernandes2@yahoo.com.br [Universidade Federal do Rio Grande do Sul (UFRS), RS (Brazil)

    2011-07-01

    Several studies in literature have shown that the addition of polymer additives and deflocculant has a strong influence on the mechanical properties of cements in general.The low mechanical strength is the main impediment to wider use of bone cement of calcium phosphate (CFCs) as the implant material, since they have mechanical strength which equals the maximum of trabecular bone.In order to evaluate the strength of a CFC compound alpha-tricalcium phosphate, sodium alginate were added (1%, 2% and 3% by weight) and dispersant ammonium polyacrylate (3%) in aqueous solution.Specimens were made and evaluated for density, porosity, crystalline phases and mechanical strength.The results show the increase of the mechanical properties of cement when added sodium alginate and dispersant. (author)

  17. Evaluation of mechanical strength and hydrate products evolution of calcium aluminate cement, for endodontic applications; Avaliacao da evolucao da resistencia mecanica e dos produtos de hidratacao de um cimento de aluminato de calcio, visando sua aplicacao em endodontia

    Energy Technology Data Exchange (ETDEWEB)

    Luz, A.P.; Borba, N.Z.; Pandolfelli, V.C., E-mail: anapaula.light@gmail.com, E-mail: vicpando@power.ufscar.br [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia de Materiais

    2011-07-01

    Mineral trioxide aggregate (MTA) is the most used retrograde filling cement in the endodontic area. Nevertheless, although its composition is similar to the conventional Portland cement, its high cost, long setting time and low mechanical strength have led to a continuous search for new alternative materials. Considering these aspects, the mechanical strength and crystalline phase evolution of a calcium aluminate cement (CAC), during its hydration process, have been evaluated in this work aiming to apply such material for endodontic treatments. Secar 71 cement samples were prepared and kept in contact with water or SBF (simulated body fluid) during 15 days at 37 deg C. Compressive strength, apparent porosity, X ray diffraction and thermogravimetric tests were carried out for the samples evaluation after 1, 3, 7 and 15 days. The main identified phases were CAH{sub 10}, C{sub 2}AH{sub 8}, C{sub 3}AH{sub 6} and AH{sub 3}. Moreover, when in the presence of SBF, some changes in the amount of the hydrates in the CAC samples were observed, which affected the mechanical behavior of the cement. (author)

  18. Characterization of the calcium-fluoroaluminosilicate glass prepared by a non-hydrolytic sol-gel route for future dental application as glass ionomer cement

    Directory of Open Access Journals (Sweden)

    Alexandre Cestari

    2009-06-01

    Full Text Available Glass ionomer cements are widely employed in dentistry due to their physical, biological and mainly anti-caries properties. Glass ionomers consist of an aluminosilicate glass matrix modified with other elements, and they contain large quantities of fluorine. In this study, we report on the preparation of calcium-fluoroaluminosilicate glasses by a nonhydrolytic sol-gel route as an alternative approach to obtaining alumina-silica matrices. The glass powders were prepared via the non-hydrolytic sol-gel method, by mixing AlCl3, SiCl4, CaF2, AlF3, NaF, and AlPO4. The powders were studied by thermal analysis (TG/DTA/DSC, photoluminescence (PL, nuclear magnetic resonance (NMR27Al-29Si, and X ray diffraction (XRD. TG/DTA/DSC analyses revealed a constant mass loss due to structural changes during the heating process, which was confirmed by NMR and PL. A stable aluminosilicate matrix with potential future application as a glass ionomer base was obtained.

  19. Effects of the addition of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on mechanical properties of luting and lining glass ionomer cement

    Science.gov (United States)

    Heravi, Farzin; Bagheri, Hossein; Rangrazi, Abdolrasoul; Mojtaba Zebarjad, Seyed

    2016-07-01

    Recently, the addition of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) into glass ionomer cements (GICs) has attracted interest due to its remineralization of teeth and its antibacterial effects. However, it should be investigated to ensure that the incorporation of CPP-ACP does not have significant adverse effects on its mechanical properties. The purpose of this study was to evaluate the effects of the addition of CPP-ACP on the mechanical properties of luting and lining GIC. The first step was to synthesize the CPP-ACP. Then the CPP-ACP at concentrations of 1%, 1.56% and 2% of CPP-ACP was added into a luting and lining GIC. GIC without CPP-ACP was used as a control group. The results revealed that the incorporation of CPP-ACP up to 1.56%(w/w) increased the flexural strength (29%), diametral tensile strength (36%) and microhardness (18%), followed by a reduction in these mechanical properties at 2%(w/w) CPP-ACP. The wear rate was significantly decreased (23%) in 1.56%(w/w) concentration of CPP-ACP and it was increased in 2%(w/w). Accordingly, the addition of 1.56%(w/w) CPP-ACP into luting and lining GIC had no adverse effect on the mechanical properties of luting and lining GIC and could be used in clinical practice.

  20. Delivering MC3T3-E1 cells into injectable calcium phosphate cement through alginate-chitosan microcapsules for bone tissue engineering*

    Science.gov (United States)

    Qiao, Peng-yan; Li, Fang-fang; Dong, Li-min; Xu, Tao; Xie, Qiu-fei

    2014-01-01

    Objective: To deliver cells deep into injectable calcium phosphate cement (CPC) through alginate-chitosan (AC) microcapsules and investigate the biological behavior of the cells released from microcapsules into the CPC. Methods: Mouse osteoblastic MC3T3-E1 cells were embedded in alginate and AC microcapsules using an electrostatic droplet generator. The two types of cell-encapsulating microcapsules were then mixed with a CPC paste. MC3T3-E1 cell viability was investigated using a Wst-8 kit, and osteogenic differentiation was demonstrated by an alkaline phosphatase (ALP) activity assay. Cell attachment in CPC was observed by an environment scanning electron microscopy. Results: Both alginate and AC microcapsules were able to release the encapsulated MC3T3-E1 cells when mixed with CPC paste. The released cells attached to the setting CPC scaffolds, survived, differentiated, and formed mineralized nodules. Cells grew in the pores concomitantly created by the AC microcapsules in situ within the CPC. At Day 21, cellular ALP activity in the AC group was approximately four times that at Day 7 and exceeded that of the alginate microcapsule group (Pmicrocapsules had a diameter of several hundred microns and were spherical compared with those formed by alginate microcapsules. Conclusions: AC microcapsule is a promising carrier to release seeding cells deep into an injectable CPC scaffold for bone engineering. PMID:24711359

  1. Delivering MC3T3-E1 cells into injectable calcium phosphate cement through alginate-chitosan microcapsules for bone tissue engineering.

    Science.gov (United States)

    Qiao, Peng-yan; Li, Fang-fang; Dong, Li-min; Xu, Tao; Xie, Qiu-fei

    2014-04-01

    To deliver cells deep into injectable calcium phosphate cement (CPC) through alginate-chitosan (AC) microcapsules and investigate the biological behavior of the cells released from microcapsules into the CPC. Mouse osteoblastic MC3T3-E1 cells were embedded in alginate and AC microcapsules using an electrostatic droplet generator. The two types of cell-encapsulating microcapsules were then mixed with a CPC paste. MC3T3-E1 cell viability was investigated using a Wst-8 kit, and osteogenic differentiation was demonstrated by an alkaline phosphatase (ALP) activity assay. Cell attachment in CPC was observed by an environment scanning electron microscopy. Both alginate and AC microcapsules were able to release the encapsulated MC3T3-E1 cells when mixed with CPC paste. The released cells attached to the setting CPC scaffolds, survived, differentiated, and formed mineralized nodules. Cells grew in the pores concomitantly created by the AC microcapsules in situ within the CPC. At Day 21, cellular ALP activity in the AC group was approximately four times that at Day 7 and exceeded that of the alginate microcapsule group (Pmicrocapsules had a diameter of several hundred microns and were spherical compared with those formed by alginate microcapsules. AC microcapsule is a promising carrier to release seeding cells deep into an injectable CPC scaffold for bone engineering.

  2. RhBMP-2 loaded 3D-printed mesoporous silica/calcium phosphate cement porous scaffolds with enhanced vascularization and osteogenesis properties

    Science.gov (United States)

    Li, Cuidi; Jiang, Chuan; Deng, Yuan; Li, Tao; Li, Ning; Peng, Mingzheng; Wang, Jinwu

    2017-01-01

    A major limitation in the development of effective scaffolds for bone regeneration has been the limited vascularization of the regenerating tissue. Here, we propose the development of a novel calcium phosphate cement (CPC)-based scaffold combining the properties of mesoporous silica (MS) with recombinant human bone morphogenic protein-2 (rhBMP-2) to facilitate vascularization and osteogenesis. Specifically, the development of a custom MS/CPC paste allowed the three-dimensional (3D) printing of scaffolds with a defined macroporous structure and optimized silicon (Si) ions release profile to promote the ingrowth of vascular tissue at an early stage after implantation in support of tissue viability and osteogenesis. In addition, the scaffold microstructure allowed the prolonged release of rhBMP-2, which in turn significantly stimulated the osteogenesis of human bone marrow stromal cells in vitro and of bone regeneration in vivo as shown in a rabbit femur defect repair model. Thus, the combination MS/CPC/rhBMP-2 scaffolds might provide a solution to issues of tissue necrosis during the regeneration process and therefore might be able to be readily developed into a useful tool for bone repair in the clinic.

  3. In Vitro Cytotoxicity and Setting Time Assessment of Calcium-Enriched Mixture Cement, Retro Mineral Trioxide Aggregate and Mineral Trioxide Aggregate.

    Science.gov (United States)

    Pornamazeh, Tahereh; Yadegari, Zahra; Ghasemi, Amir; Sheykh-Al-Eslamian, Seyedeh Mahsa; Shojaeian, Shiva

    2017-01-01

    The present study sought to evaluate and compare biocompatibility and setting time of Retro mineral trioxide aggregate (MTA), calcium-enriched mixture (CEM) and Angelus MTA. CEM cement, Angelus MTA and Retro MTA were assessed in set and fresh states. Extracts transformed to each cavity of three 24-well plates in which 1×104 cell were seeded into each well 24 h earlier. All specimens were incubated in a humidified incubator with 5% CO2 at 37°C. Mosmann's tetrazolium toxicity (MTT) assay was used to determine in vitro cytotoxicity on L929 mouse fibroblast cell line. Cell viability was determined at 1, 24, and 72 h after exposure. The initial setting time was measured by 113.4 g Gilmore needle testing. Then, final setting times were assessed by the 456.5 g Gilmore needle. Data comparisons were performed using the analysis of variance (ANOVA) and Tukey's post hoc test (α=0.05). All groups in both forms indicated higher cell vitality compared to positive control group (PMTA showed better biocompatibility compared to set CEM and set Angelus MTA (PMTA showed significantly lower initial and final setting time compared to CEM and Angelus MTA (PMTA and relatively short period of setting time. It seems a promising alternative material in clinical situations where accelerated setting is required. However, more clinical and in vivo investigations are needed for a clear decision making.

  4. Design and Fabrication of Complex Scaffolds for Bone Defect Healing: Combined 3D Plotting of a Calcium Phosphate Cement and a Growth Factor-Loaded Hydrogel.

    Science.gov (United States)

    Ahlfeld, Tilman; Akkineni, Ashwini Rahul; Förster, Yvonne; Köhler, Tino; Knaack, Sven; Gelinsky, Michael; Lode, Anja

    2017-01-01

    Additive manufacturing enables the fabrication of scaffolds with defined architecture. Versatile printing technologies such as extrusion-based 3D plotting allow in addition the incorporation of biological components increasing the capability to restore functional tissues. We have recently described the fabrication of calcium phosphate cement (CPC) scaffolds by 3D plotting of an oil-based CPC paste under mild conditions. In the present study, we have developed a strategy for growth factor loading based on multichannel plotting: a biphasic scaffold design was realised combining CPC with VEGF-laden, highly concentrated hydrogel strands. As hydrogel component, alginate and an alginate-gellan gum blend were evaluated; the blend exhibited a more favourable VEGF release profile and was chosen for biphasic scaffold fabrication. After plotting, two-step post-processing was performed for both, hydrogel crosslinking and CPC setting, which was shown to be compatible with both materials. Finally, a scaffold was designed and fabricated which can be applied for testing in a rat critical size femur defect. Optimization of CPC plotting enabled the fabrication of highly resolved structures with strand diameters of only 200 µm. Micro-computed tomography revealed a precise strand arrangement and an interconnected pore space within the biphasic scaffold even in swollen state of the hydrogel strands.

  5. Strontium doping promotes bioactivity of rhBMP-2 upon calcium phosphate cement via elevated recognition and expression of BMPR-IA.

    Science.gov (United States)

    Huang, Baolin; Tian, Yu; Zhang, Wenjing; Ma, Yifan; Yuan, Yuan; Liu, Changsheng

    2017-11-01

    Preserving and improving osteogenic activity of bone morphogenetic protein-2 (BMP-2) upon implants remains one of the key limitations in bone regeneration. With calcium phosphate cement (CPC) as model, we have developed a series of strontium (Sr)-doped CPC (SCPC) to address this issue. The effects of fixed Sr on the bioactivity of recombinant human BMP-2 (rhBMP-2) as well as the underlying mechanism were investigated. The results suggested that the rhBMP-2-induced osteogenic activity was significantly promoted upon SCPCs, especially with a low amount of fixed Sr (SrCO 3 content <10wt%). Further studies demonstrated that the Sr-induced enhancement of bioactivity of rhBMP-2 was related to an elevated recognition of bone morphogenetic protein receptor-IA (BMPR-IA) to rhBMP-2 and an increased expression of BMPR-IA in C2C12 model cells. As a result, the activations of BMP-induced signaling pathways were different in C2C12 cells incubated upon CPC/rhBMP-2 and SCPCs/rhBMP-2. These findings explicitly decipher the mechanism of SCPCs promoting osteogenic bioactivity of rhBMP-2 and signify the promising application of the SCPCs/rhBMP-2 matrix in bone regeneration implants. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Evaluation and Comparison of Occurrence of Tooth Discoloration after the Application of Various Calcium Silicate-based Cements: An Ex Vivo Study.

    Science.gov (United States)

    Shokouhinejad, Noushin; Nekoofar, Mohammad H; Pirmoazen, Salma; Shamshiri, Ahmad R; Dummer, Paul M H

    2016-01-01

    Biodentine (Septodont, Saint Maur des Fossés, France), OrthoMTA (BioMTA, Seoul, Korea), and EndoSequence Root Repair Material (ERRM; Brasseler, Savannah, GA) have been developed to overcome the shortcomings of mineral trioxide aggregate (MTA). The purpose of this study was to compare tooth discoloration after the application of ProRoot MTA (Dentsply Tulsa Dental Products, Tulsa, OK) and 3 recently introduced calcium silicate-based cements in the presence and absence of blood. In total, 104 human anterior teeth were prepared; 96 were randomly divided into 2 groups (blood and saline contamination). Each group was subdivided into 4 experimental subgroups (n = 12) of ProRoot MTA, Biodentine, OrthoMTA, and ERRM that were used to fill the pulp chambers. The remaining 8 teeth served as the saline and blood groups. Color analysis of tooth crowns was performed using a spectroradiometer before the application of materials and at 24 hours, 1 month, and 6 months after application. Repeated measures analysis of variance was used to evaluate the effects of blood, material, and time on color change (ΔE*). Tooth color change in all experimental groups increased over time (P discolorations with materials in the presence of blood. However, in the absence of blood, Biodentine and ERRM exhibited less tooth discoloration than OrthoMTA. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  7. X-ray spectra and theoretical elastic properties of crystalline calcium silicate hydrates: comparison with cement hydrated gels

    Directory of Open Access Journals (Sweden)

    Ayuela, A.

    2010-09-01

    Full Text Available For 22 crystalline Calcium Silicates Hydrates, we have calculated their structure and their elastic properties by atomistic force field methods as well as simulate their Xray diffraction patterns. From the computed Young moduli, it can be suggested that the key parameters to determine the elastic properties of crystalline Calcium Silicate Hydrates are densities and water content. We have compared these trends with those of cementitious C-S-H gel and synthetic C-S-H type I as a function of their C/S ratios and nominal water content. Our comparison show that the experimentally suggested values of density and Young moduli for C-S-H gel lie in the range of the calculated CSH crystals. However, we conclude that a detailed correspondence might require investigating structurally within CSH gels the role of water and especially of Ca and Si sites through their C/S ratio.

    En este trabajo se han calculado para 22 Silicatos Cálcicos Hidratados cristalinos, su estructura y sus propiedades elásticas mediante métodos atomísticos “force field”, así como simulado sus espectros de difracción de rayos X. De los módulos de Young calculados se puede deducir, que los parámetros clave que determinan las propiedades elásticas de los Silicatos Cálcicos Hidratados cristalinos son la densidad y el contenido en agua. Nuestros resultados muestran que los valores experimentales de la densidad y de los módulos de Young para el gel C-S-H están dentro del rango de los cristales de CSH calculados. Sin embargo, podemos concluir que para establecer una correlación más directa sería necesario investigar el papel que juegan el agua y sobre todo el Ca y Si, mediante la relación C/S, en la estructura del gel CSH.

  8. 1-year In Vitro Evaluation of Tooth Discoloration Induced by 2 Calcium Silicate-based Cements.

    Science.gov (United States)

    Ramos, João Carlos; Palma, Paulo J; Nascimento, Rita; Caramelo, Francisco; Messias, Ana; Vinagre, Alexandra; Santos, João Miguel

    2016-09-01

    The purpose of this study was to compare tooth discoloration that occurs in teeth filled with ProRoot MTA (DENTSPLY Tulsa Dental Specialties, Tulsa, OK) or Biodentine (Septodont, Saint Maur des Fossés, France) over the course of 1 year. Twenty-eight intact premolars were resected 2 mm apical to the cementoenamel junction and the pulp tissues extirpated via the cervical cut. After the preparation of occlusal access to the pulp chamber, specimens were assigned into 4 groups according to a stratified randomization sampling process: group 1, negative control (dry sterile cotton pellet); group 2, positive control (blood-moistened cotton pellet); group 3, ProRoot WMTA (DENTSPLY Tulsa Dental Specialties); and group 4, Biodentine. The experimental materials were condensed into the crowns and the access sealed with glass ionomer restorative cement. Color was assessed at baseline (before placement of the materials), immediately after material filling, after 6 weeks of storage, and after 1 year using the Commission International de I'Eclairage L*a*b* system. Change in color, ΔE, was compared among groups and over time using analysis of variance. The 4 groups showed a significant decrease in L* values over time. Differences between Biodentine and WMTA were detected after 1 year, with the greater variation associated with WMTA (P = .001). The 4 groups presented a significant increase in ΔE from baseline to 1 year. All groups revealed perceptible color changes (ΔE > 2.3) between immediately after material filling and after 6 weeks and after 6 weeks and 1 year. After 1 year, no differences could be detected between Biodentine and WMTA. Delayed tooth discoloration was detected for the 2 materials at the 1-year evaluation, but it was more evident for ProRoot MTA than Biodentine. Luminance was the most affected parameter, with a higher decrease for ProRoot MTA. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  9. PART II. HYDRATED CEMENTS

    Directory of Open Access Journals (Sweden)

    Milan Drabik

    2014-09-01

    Full Text Available Essential focus of the study has been to acquire thermoanalytical events, incl. enthalpies of decompositions - ΔH, of technological materials based on two types of Portland cements. The values of thermoanalytical events and also ΔH of probes of technological compositions, if related with the data of a choice of minerals of calcium-silicate-sulfate-aluminate hydrates, served as a valued input for the assessment of phases present and phase changes due to the topical hydraulic processes. The results indicate mainly the effects of "standard humidity" or "wet storage" of the entire hydration/hydraulic treatment, but also the presence of cement residues alongside calcium-silicate-sulfate-aluminate hydrates (during the tested period of treatment. "A diluting" effect of unhydrated cement residues upon the values of decomposition enthalpies in the studied multiphase system is postulated and discussed

  10. The synergistic effects of CO2 laser treatment with calcium silicate cement of antibacterial, osteogenesis and cementogenesis efficacy

    Science.gov (United States)

    Hsu, T.-T.; Kao, C.-T.; Chen, Y.-W.; Huang, T.-H.; Yang, J.-J.; Shie, M.-Y.

    2015-05-01

    Calcium silicate-based material (CS) has been successfully used in dental clinical applications. Some researches show that the antibacterial effects of CO2 laser irradiation are highly efficient when bacteria are embedded in biofilm, due to a photo-thermal mechanism. The purpose of this study was to confirm the effects of CO2 laser irradiation on CS, with regard to both material characterization and human periodontal ligament cell (hPDLs) viability. CS was irradiated with a dental CO2 laser using directly mounted fiber optics in wound healing mode with a spot area of 0.25 cm2, and then stored in an incubator at 100% relative humidity and 37 °C for 1 d to set. The hPDLs cultured on CS were analyzed, along with their proliferation and odontogenic differentiation behaviors. The results indicate that the CO2 laser irradiation increased the amount of Ca and Si ions released from the CS, and regulated cell behavior. CO2 laser-irradiated CS promoted cementogenic differentiation of hPDLs, with the increased formation of mineralized nodules on the substrate’s surface. It also up-regulated the protein expression of multiple markers of cementogenic and the expression of cementum attachment protein. The current study provides new and important data about the effects of CO2 laser irradiation on CS. Taking cell functions into account, the Si concentration released from CS with laser irradiated may be lower than a critical value, and this information could lead to the development of new regenerative therapies for dentin and periodontal tissue.

  11. [An experimental study on a slow-release complex with rifampicin-polylactic-co-glycolic acid-calcium 
phosphate cement].

    Science.gov (United States)

    Wu, Jianhuang; Ding, Zhou; Lei, Qing; Li, Miao; Liang, Yan; Lu, Tao

    2016-09-28

    To prepare the slow-release complex with rifampicin (RFP)-polylactic-co-glycolic acid (PLGA)-calcium phosphate cement (CPC) (RFP-PLGA-CPC complex), and to study its physical and chemical properties and drug release properties in vitro.
 The emulsification-solvent evaporation method was adopted to prepare rifampicin polylactic acid-glycolic acid (RFP-PLGA) slow-release microspheres, which were divided into 3 groups: a calcium phosphate bone cement group (CPC group), a CPC embedded with RFP group (RFP-CPC group), and a PLGA slow-release microspheres carrying RFP and the self-curing CPC group (RFP- PLGA-CPC complex group). The solidification time and porosity of materials were determined. The drug release experiments in vitro were carried out to observe the compressive strength, the change of section morphology before and after drug release. 
 The CPC group showed the shortest solidification time, while the RFP-PLGA-CPC complex group had the longest one. There was statistical difference in the porosity between the CPC group and the RFP-CPC group (P<0.05); Compared to the RFP-PLGA-CPC complex group, the porosity in the CPC group and the RFP-CPC group were significantly changed (both P<0.01). There was significant difference in the compressive strength between the RFP- PLGA-CPC complex group and the CPC group (P<0.01), while there was significant difference in the compressive strength between the RFP-CPC group and the CPC group (3 days: P<0.05; 30 and 60 days: P<0.01). The change of the compressive strength in the CPC was not significant in the whole process of degradation. The sizes of PLGA microspheres were uniform, with the particle size between 100-150 μm. The microspheres were spheres or spheroids, and their surface was smooth without the attached impurities. There was no significant change in the section gap in the CPC group after soaking for 3 to 60 days. The microstructure change in the RFP-CPC group was small, and the cross section was formed by small

  12. Engineering of bone using porous calcium phosphate cement and bone marrow stromal cells for maxillary sinus augmentation with simultaneous implant placement in goats.

    Science.gov (United States)

    Zou, Derong; Guo, Lian; Lu, Jiayu; Zhang, Xiuli; Wei, Jie; Liu, Changsheng; Zhang, Zhiyuan; Jiang, Xinquan

    2012-07-01

    The aim of this study was to explore the effects of maxillary sinus floor elevation and simultaneous dental implantation with a tissue-engineered bone complex of calcium phosphate cement (CPC) scaffolds combined with bone marrow stromal cells (BMSCs). A large animal goat model is used with the tissue engineering method. Eighteen bilateral maxillary sinus of nine goats were randomly allocated into three groups; the CPC/BMSC complex (n=6) was used to elevate maxillary sinus floor with a simultaneous implant placement; the effects were compared with those treated with CPC alone (n=6) or autogenous bone (n=6). After a healing period of 3 months, sequential triad-color fluorescence labeling, micro-CT, as well as histological and histomorphometric analyses indicated that the tissue-engineered BMSC/CPC complex could promote earlier bone formation and mineralization, and maximally maintain the volume and height of the augmented maxillary sinus. By comparison, CPC-alone or autogenous bone achieved less bone formation and later mineralization. Besides, the average bone-implant contact value reflecting the osseointegration was 35.63%±9.42% in the BMSCs/CPC group, significantly higher than 22.47%±4.28% in the CPC-alone group or 28.26%±8.03% in the autogenous bone group. In conclusion, CPC serves as a potential substrate for BMSCs for the maxillary sinus floor augmentation and simultaneous implantation. The tissue-engineered bone might enhance the stability of implants and thus be of great significance to achieve improved quality to restore the oral function in clinic.

  13. Structural study and crystallography of the major compound of anhydrous cement: tri-calcium silicate; Etude structurale et cristallographie du compose majoritaire du ciment anhydre: le silicate tricalcique

    Energy Technology Data Exchange (ETDEWEB)

    Noirfontaine, M.N. de

    2000-01-01

    Anhydrous (Portland) cement is mainly composed of a synthetic material, the clinker, whose major compound is tri-calcium silicate (Ca{sub 3}SiO{sub 5}), often referred as C{sub 3}S with the compact oxides notations, C = CaO et S = SiO{sub 2}. The polymorphism of C{sub 3}S, still not well known, is the main subject of the thesis. Various crystal structures (rhombohedral R, monoclinic M1, M2, M3 and triclinic T1, T2, T3) can be found, depending on temperature and impurities. The only known structures are T1, M1 and M3, involving large unit cells with an orientational disorder of silicate tetrahedra. The single crystal studies exhibit no clear relation between the various polymorphs. Starting from known results from literature single crystal experiments, we establish the metric and structural relations between the different structures. Averaged structures for the T1, M1 and M3 polymorphs are proposed, together with all the matrices of transformation between the unit cells. We also introduce new 1-D, 2-D, and 3-D structural units, which make easier the understanding of the structures of C{sub 3}S, with the result of a better description of the orientational disorder. The effects of impurities on the structure are discussed. In industrial clinkers, impurities stabilize mainly M1 and M3 monoclinic forms. We propose a space group (Pc) and two structural models (a superstructure and an approximate averaged structure) for the M1 form. All the models are validated on synthetic compounds (M3, M2, M1 et T1) and industrial clinkers analysed by X-Ray powder diffraction with Rietveld analysis. (author)

  14. Hydration kinetics for the alite, belite, and calcium aluminate phase in Portland cements from 27Al and 29Si MAS NMR spectroscopy

    DEFF Research Database (Denmark)

    Skibsted, Jørgen; Jensen, Ole Mejlhede; Jakobsen, Hans Jørgen

    1997-01-01

    29Si magic-angle spinning (MAS) NMR spectroscopy is shown to be a valuable tool for obtaining the quantities of alite and belite in hydrated Portland cements. The hydration (1-180 days) of a white Portland cement with 10 wt.% silica fume added is investigated and the degrees of hydration for alit...

  15. Sealing ability of mineral trioxide aggregate, calcium phosphate and polymethylmethacrylate bone cements on root ends prepared using an Erbium: Yttriumaluminium garnet laser and ultrasonics evaluated by confocal laser scanning microscopy.

    Science.gov (United States)

    Girish, C Sabari; Ponnappa, Kc; Girish, Tn; Ponappa, Mc

    2013-07-01

    Surgical endodontic therapy comprises of exposure of the involved root apex, resection of the apical end of the root, preparation of a class I cavity, and insertion of a root end filling material. Mineral trioxide aggregate (MTA) is now the gold standard among all root end filling materials. MTA is however difficult to handle, expensive and has a very slow setting reaction. (1) To compare the sealing ability of MTA, polymethylmethacrylate (PMMA) bone cement and CHITRA Calcium phosphate cement (CPC) when used as root end filling material using Rhodamine B dye evaluated under a confocal laser scanning microscope. (2) To compare the seal of root ends prepared using an ultrasonic retroprep tip and an Er: YAG laser using three different root end filling materials. Statistical analysis was performed using a one-way ANOVA and a two-way ANOVA, independent samples t-test and Scheffe's post hoc test using SPSS Version 16 for Windows. All the three materials, namely MTA, PMMA BONE CEMENT and CHITRA CPC, showed microleakage. Comparison of microleakage showed maximum peak value of 0.86 mm for MTA, 0.24 mm for PMMA bone cement and 1.37 mm for CHITRA CPC. The amount of dye penetration was found to be lesser in root ends prepared using Er: YAG laser when compared with ultrasonics, but the difference was found to be not statistically significant. PMMA bone cement is a better material as root end filling material to prevent apical microleakage. MTA still continues to be a gold standard root end filling material showing minimum microleakage. Er: YAG laser is a better alternative to ultrasonics for root end preparations.

  16. Radiopacity of calcium hydroxide cement compared with human tooth structure Radiopacidade do cimento de hidróxido de cálcio comparada a das estruturas dentais humanas

    Directory of Open Access Journals (Sweden)

    Karina Lopes Devito

    2004-12-01

    Full Text Available AIMS: All materials added to teeth should present an adequate radiopacity to allow the detection of secondary caries. Usually, in extensive cavities, base materials like calcium hydroxide cement are used for the purpose of protecting the pulp. In an attempt to improve the efficiency of radiographic detection of this material, this study aimed to determine the radiopacity of three calcium hydroxide cements and to compare the radiopacity of these materials with dentin and enamel. METHODS: Radiographs were taken of 1-mm thick specimens of three calcium hydroxide cements: Hydro-C, Dycal and Life, an aluminium stepwedge, a lead foil, and one 1-mm thick human tooth slice. Densitometric measurements were obtained after radiographic processing. The radiopacity values of the calcium hydroxide cements, dentin and enamel were expressed in terms of the equivalent thickness of aluminium. RESULTS: The analysis of variance indicated statistically significant difference only for Life, which presented the lowest radiopacity when compared to the other cements. However, all cements and enamel possessed a radiopacity equivalent to 2mm Al, while dentin presented a radiopacity equivalent to 1mm Al. CONCLUSION: All tested cements presented a similar radiopacity to that of enamel and they meet the ISO 4049 specifications.OBJETIVOS: Todos os materiais adicionados aos dentes deveriam apresentar uma adequada radiopacidade para permitir a detecção de cáries secundárias. Geralmente em cavidades extensas, materiais de base, como o cimento de hidróxido de cálcio, são usados com a função de proteger a polpa. Na tentativa de melhorar a eficiência na detecção radiográfica deste material, este estudo foi realizado com o objetivo de determinar a radiopacidade de três cimentos de hidróxido de cálcio e comparar a radiopacidade destes materiais com a da dentina e do esmalte. MATERIAIS E MÉTODO: Foram radiografados corpos de prova de 1 mm de espessura de tr

  17. Maxillary sinus floor elevation with a tissue-engineered bone composite of deciduous tooth stem cells and calcium phosphate cement in goats.

    Science.gov (United States)

    Zhao, Wei; Lu, Jia-Yu; Hao, Yong-Ming; Cao, Chun-Hua; Zou, De-Rong

    2017-01-01

    The study aimed to assess the effect of maxillary sinus floor elevation with tissue-engineered bone constructed from deciduous tooth stem cells (DTSCs) and calcium phosphate cement (CPC). The stem cells from goat deciduous teeth (SGDs) were isolated and transfected by means of the adenovirus with an enhanced green fluorescent protein gene (AdEGFP). As many as 18 bilateral maxillary sinuses of nine goats were randomly allocated into three groups (n = 6/group): group A (SGDs-CPC compound), group B (CPC alone) and group C (autogenous bone obtained from an iliac crest). All the samples were evaluated by computed tomography (CT), histology and histomorphometric analysis. Furthermore, the fate of implanted SGDs was traced using an immunohistochemical staining method in the decalcified samples. SGDs might be differentiated into osteoblasts in an osteogenic medium. In the present study, three-dimensional CT analysis showed that the volume of newly formed bone in group A was greater than that in the other two groups. After a healing period of 3 months, sequential analyses of triad-colour fluorescence labelling, histology and histomorphology indicated that the SGDs-CPC compound primarily promoted bone formation and mineralization at 2 and 3 months after the operation. Moreover, the areas of new bone formation in elevated sinuses were 41.82 ± 6.24% in the SGDs-CPC group, which was significantly higher than the 30.11 ± 8.05% in the CPC-alone group or the 23.07 ± 10.21% in the autogenous bone group. Immunohistochemical staining revealed that GFP and OCN were both expressed in the new bone tissue for the samples with eGFP, which suggested that the implanted SGDs might have contributed to new bone formation on the elevated sinus floor. SGDs can promote new bone formation and maturation in the goat maxillary sinus, and the tissue-engineered bone composite of SGDs and CPC might be a potential substitute for existing maxillary sinus floor elevation methods

  18. Calcium phosphate bone cement containing ABK and PLLA. Sustained release of ABK, the BMD of the femur in rats, and histological examination

    Energy Technology Data Exchange (ETDEWEB)

    Kusaka, T.; Tanaka, A.; Sasaki, S.; Takano, I.; Tahara, Y.; Ishii, Y. [Kyorin Univ., Tokyo (Japan). Dept. of Orhtopaedic Surgery

    2001-07-01

    Bone cement was prepared by mixing CPC95 (Mitsubishi Material Co., Ltd.), ABK, and PLLA at a ratio of 14 : 1 : 2. In vitro, Antibiotic sustained release tests were performed by the total amount exchange method. In animal experiments, the bone cement was infused into the right femur of 18-month-old female SD rats. After 1, 2, 4, or 6 months, the BMD was determined by DXA in the bilateral femoral bones. In addition, hard tissue specimens were prepared, and the state of bone formation was observed. The release of the antibiotic was 1.73 {mu}g/ml until 18 days after administration, maintaining a concentration over the MIC80 for MRSA. In the animal experiments, the BMD significantly increased after 2 - 4 months. In the hard tissue specimens, direct binding on the bone-cement interface and bone formation in the cement were observed after 1 month. (orig.)

  19. Cement Formation

    DEFF Research Database (Denmark)

    Telschow, Samira; Jappe Frandsen, Flemming; Theisen, Kirsten

    2012-01-01

    Cement production has been subject to several technological changes, each of which requires detailed knowledge about the high multiplicity of processes, especially the high temperature process involved in the rotary kiln. This article gives an introduction to the topic of cement, including...... an overview of cement production, selected cement properties, and clinker phase relations. An extended summary of laboratory-scale investigations on clinkerization reactions, the most important reactions in cement production, is provided. Clinker formations by solid state reactions, solid−liquid and liquid...

  20. Subgrade stabilization alternatives to lime and cement.

    Science.gov (United States)

    2010-04-15

    This project involved four distinct research activities, (1) the influence of temperature on lime-stabilized soils, (2) the influence of temperature on cement-stabilized soils (3) temperature modeling of stabilized subgrade and (4) use of calcium chl...

  1. Examination of Cement Pastes Hydrated Phases, and Synthetic Products by X-Ray Diffraction

    Science.gov (United States)

    1972-04-01

    F. E. Jones, Hydration of Calcium Aluminates and Ferrites , Fourth International Symposium on the Chemistry of Cement, Washington, D. C., 1960, Vol 1...hydrated calcium aluminates and ferrites , Proc Fifth Inte-national Symposium on the Chemistry of Cement, Tokyo, 1968, 196-. pp 37-67; discussion by M. H...water-cement ratio contained ettringite, tetracalcium aluminate inonos-2;irate-12-hydrate, calcium hydroxide, calcium silicate hydrate gel, and

  2. Computational Modeling of Multi-Scale Material Features in Cement Paste - An Overview

    Science.gov (United States)

    2015-05-25

    engineering. 2 NANOSCALE MATERIAL CHEMISTRY LEVEL MODELING Portland cement in the powder form consists of four different major constituents: Tri...Calcium silicate (C3S), Di-Calcium silicate (C2S), Tri-Calcium aluminate (C3A), and Tetra calcium aluminoferrite (C4AF) [1]. Hydration of cement is the...distribution (PSD), volume fractions and surface area fractions of the constituent phases for the cement powder , extracted from 2D composite SEM (scanning

  3. Development of hydroxyapatite bone cement for controlled drug ...

    Indian Academy of Sciences (India)

    The results of this study demonstrate the potential of using HA cement as a carrier for drug delivery. Keywords. Calcium phosphate; bone cement; tetracycline hydrochloride; drug delivery. 1. Introduction. Calcium phosphates are becoming increasingly popular in the field of biomedical, in particular, dentistry, bone substi-.

  4. Comparative evaluation of the calcium release from mineral trioxide aggregate and its mixture with glass ionomer cement in different proportions and time intervals – An in vitro study

    Directory of Open Access Journals (Sweden)

    Surbhi Sawhney

    2015-10-01

    Conclusions: Adding GIC to improve the setting time and handling properties of the MTA powder can be detrimental to the calcium-releasing ability of the resultant mixture, depending on the proportion of GIC added. Adding MTA and GIC at a proportion of 2:1 by volume did not impact calcium release from the mixture. These findings should be verified through further clinical studies.

  5. Optimization of properties of cement-bonded particleboard manufactured from cotton stalk and sawdust containing calcium chloride CaCl2 as an additive

    Directory of Open Access Journals (Sweden)

    morteza nazerian

    2016-06-01

    Full Text Available The aim of this study was investigation of hydration behavior and mechanical properties of cement-bonded particleboard manufactured from different ratio of cotton stalk to poplar wood particle, sawdust content and CaCl2 as additive at different weight ratios. At the first, curing time of cement paste containing different amount of additive (CaCl2 and wood and cotton fines was determined. Besides, the effect of additive (CaCl2 content, weight ratio of cotton to poplar wood particles and percentage of sawdust on modulus of rupture (MOR, modulus of elasticity (MOE and internal bonding (IB of cement-bonded particleboard was evaluated by response surface methodology (RSM. In order to optimize the properties of panels, a mathematical model equation (second order plan was done by a computer simulation program. According to results, there is a good coincidence between predicted values and actual values (R2 for MOR, MOE and IB was 0.93, 0.90 and 0.95, respectively. This study showed that the response surface methodology (RSM can be effectively used for modeling of panel properties. Results showed that using weight ratio of cotton to poplar particle 43:57 the MOR, MOE and IB of panels can be reached to maximum values (12.5, 2545 and 0.35 MPa, respectively. Simultaneously, application of 4.5% additive and 9% sawdust at had a positive effect on the properties of the panels.

  6. Low heat cement; Teihatsunetsu cement

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, K.; Igarashi, H. [Ube Industries, Ltd., Tokyo (Japan)

    1994-09-01

    This paper summarizes the result of studies on low heat (low hydration heat) cement intended to prevent cracking. Good compositional proportions of alite and belite as components of Portland cement are belite at 63% and alite at 37% when hydration heat, strength, and concrete durability are taken into account. Mixing the blast furnace slag into cement fills the voids at low hydration heat, and raises the strength without increasing the hydration heat. However, the voids remain in a long-term material age. The strength of the belite-based cement is improved when the higher the temperature within a range from 20 to 60{degree}C. In the case of a mixed cement of belite-based cement and blast furnace slag, using the blast furnace slag at 60% maintains the strength and reduces the hydration heat. The strength decreases at a curing temperature of 60{degree}C or higher. Hardened mortar with a material age of three days has its voids disappear at 40{degree}C. More void disappearance cannot be recognized even if the material age gets older. Hydration heat decreases largely in the belite-based cement and flyash mixed cement. The strength also decreases, but it increases conversely when the material age gets as old as one year. Flyash causes the temperature to rise more moderately than blast furnace slag. 21 refs., 16 figs., 1 tab.

  7. Interaction of calcium silicate hydrates (C-S-H), the main components of cement, with alkaline chlorides, analogy with clays; Interaction des silicates de calcium hydrates, principaux constituants du ciment, avec les chlorures d'alcalins. Analogie avec les argiles

    Energy Technology Data Exchange (ETDEWEB)

    Viallis-Terrisse, H

    2000-10-06

    This work, belonging to a more general study on the structure and reactivity of cement, deals with the experimental and theoretical analysis of the interaction of alkaline chlorides with calcium silicate hydrates (C-S-H), the main components of cement paste. The interaction of alkaline cations with C-S-H is interfacial, involving both electrostatic and surface complexation mechanisms. The C-S-H surface is constituted of silanol sites, partially dissociated due to the high pH of the interstitial solution. The calcium ions, present in large amounts in the equilibrium solution of C-S-H, constitute potential determining ions for the C-S-H surface. The alkaline ions seem to compete with calcium for the same surface sites. The adsorption isotherms show that caesium presents a better affinity than sodium and lithium for the C-S-H surface. Moreover, solid-state NMR suggests that caesium forms with the surface sites inner-sphere complexes, whereas sodium seems to keep its hydration sphere. These results are in agreement with zeta potential measurements, which let suppose a specific adsorption of caesium ions, and an indifferent behaviour of both other alkaline ions. A model for the C-S-H surface was proposed, from the electric double layer model, and mass action laws expressing the complexation of the different ionic species with the silanol sites. The whole study relies on a structural analogy with smectites, some clays presenting well-known cationic adsorption properties. The structural similarity between both minerals is enhanced by some similarities of reactivity, though significant behaviour differences could also be noted. (author)

  8. The formation of tertiary dentin after pulp capping with a calcium phosphate cement, loaded with PLGA microparticles containing TGF-beta1.

    NARCIS (Netherlands)

    Zhang, W.; Walboomers, X.F.; Jansen, J.A.

    2008-01-01

    The aim of the current study was to evaluate the effect of a calcium phosphate material equipped with poly (lactic-co-glycolic acid) microspheres for pulp capping, and to measure the dentin bridge formation, when using various concentrations of transforming growth factor (TGF) beta1. Preset samples

  9. Quantitative X-ray pair distribution function analysis of nanocrystalline calcium silicate hydrates: a contribution to the understanding of cement chemistry.

    Science.gov (United States)

    Grangeon, Sylvain; Fernandez-Martinez, Alejandro; Baronnet, Alain; Marty, Nicolas; Poulain, Agnieszka; Elkaïm, Erik; Roosz, Cédric; Gaboreau, Stéphane; Henocq, Pierre; Claret, Francis

    2017-02-01

    The structural evolution of nanocrystalline calcium silicate hydrate (C-S-H) as a function of its calcium to silicon (Ca/Si) ratio has been probed using qualitative and quantitative X-ray atomic pair distribution function analysis of synchrotron X-ray scattering data. Whatever the Ca/Si ratio, the C-S-H structure is similar to that of tobermorite. When the Ca/Si ratio increases from ∼0.6 to ∼1.2, Si wollastonite-like chains progressively depolymerize through preferential omission of Si bridging tetrahedra. When the Ca/Si ratio approaches ∼1.5, nanosheets of portlandite are detected in samples aged for 1 d, while microcrystalline portlandite is detected in samples aged for 1 year. High-resolution transmission electron microscopy imaging shows that the tobermorite-like structure is maintained to Ca/Si > 3.

  10. Cimento aluminoso e seus efeitos em concretos refratários magnesianos espinelizados in situ Calcium aluminate cement and its effects on in-situ spinel containing magnesia refractory castables

    Directory of Open Access Journals (Sweden)

    D. H Milanez

    2010-03-01

    Full Text Available O uso de concretos refratários alumina-magnésia ligados por cimento aluminoso (CAC apresenta vantagens decorrentes da presença de espinélio e de CA6 (CaO.6Al2O3, ambas formadas in-situ e acompanhadas de expansão. Estas fases possuem alta resistência a escórias básicas e ao choque térmico, propriedades estas imprescindíveis para aplicação em panelas siderúrgicas. Estudos anteriores mostraram que o teor de CAC utilizado em concretos alumina-magnésia influencia a expansão do material, principalmente devido à formação de CA6. Este trabalho visa estudar a influência do teor de cimento no sistema magnésia-alumina, utilizando-se a mesma matriz de um concreto alumina-magnésia tradicional. Os resultados indicaram que o CAC influencia na estabilidade volumétrica do sistema MgO-espinélio: quanto menor o teor de CAC, menor a retração das amostras. Isso refletiu na sinterização dos concretos e, assim, nas propriedades mecânicas após queima em temperaturas elevadas.Calcium aluminate cement (CAC bonded alumina-magnesia refractory castables present great advantages for steel ladle applications as a result of in-situ expansive formation of spinel and CA<6, which leads to high basic slag and thermal shock resistance. The CAC content in those castables strongly influences its expansive behavior mainly due to CA6 formation. In the present work, the effects of the CAC content in magnesia-alumina castables were analyzed. The results showed that calcium aluminate cement affects the volumetric stability of MgO-spinel system: the lower the CAC content, the lower the shrinkage. These effects on the sintering and in the mechanical properties after sintering at high temperatures are also presented and discussed.

  11. Comparative evaluation of antimicrobial action of MTA, calcium hydroxide and Portland cement Avaliação comparativa da ação antimicrobiana do MTA, hidróxido de cálcio e cimento Portland

    Directory of Open Access Journals (Sweden)

    Caroline Sousa Ribeiro

    2006-10-01

    Full Text Available The present study aimed to evaluate and compare the antimicrobial effect of MTA Dentsply, MTA Angelus, Calcium Hydroxide and Portland cement. Four reference bacterial strains were used: Pseudomonas aeruginosa, Escherichia coli, Bacteroides fragilis, and Enterococcus faecalis. Plates containing Mueller-Hinton agar supplemented with 5% sheep blood, hemin, and menadione were inoculated with the bacterial suspensions. Subsequently, wells were prepared and immediately filled with materials and incubated at 37ºC for 48 hours under anaerobic conditions, except P. aeruginosa. The diameters of inhibition zones were measured, and data analyzed using ANOVA and the Tukey test with 1% level of significance. MTA Dentsply, MTA Angelus and Portland cement inhibited the growth of P. aeruginosa. Calcium Hydroxide was effective against P. aeruginosa and B. fragillis. Under anaerobic conditions, which may hamper the formation of reactive oxygen species, the materials failed to inhibit E. faecalis, and E. coli.O objetivo do presente trabalho foi avaliar e comparar o efeito antimicrobiano do MTA Dentsply, MTA Angelus, hidróxido de cálcio e cimento Portland sobre quatro cepas bacterianas: Pseudomonas aeruginosa, Escherichia coli, Bacteroides fragilis, e Enterococcus faecalis. Placas contendo agar Muller-Hinton suplementadas com 5% de sangue de carneiro, hemina e menadiona foram inoculadas com as suspensões bacterianas. Poços foram confeccionados com auxílio de perfuradores e imediatamente preenchidos com os materiais, e incubados a 37ºC por 48 horas em atmosfera de anaerobiose, exceto P. aeruginosa. O diâmetro dos halos de inibição foi medido e os dados analisados usando o teste estatístico ANOVA e o de Tukey com nível de significância de 1%. O MTA Dentsply, MTA Angelus e Cimento Portland inibiram o crescimento da P.aeruginosa. O hidróxido de cálcio foi efetivo contra P. aeruginosa e B. fragillis. Sob atmosfera de anaerobiose, condição que pode

  12. Changes in the drug release pattern of fresh and set simvastatin-loaded brushite cement

    OpenAIRE

    Mestres Beà, Gemma; Kugiejko, Karol; Pastorino Carraz, David; Unosson, Johanna; Ohman, Caroline; Karlsson Ott, Marjam; Ginebra Molins, Maria Pau; Persson, Cecilia

    2016-01-01

    Calcium phosphate cements are synthetic bone graft substitutes able to set at physiological conditions. They can be applied by minimally invasive surgery and can also be used as drug delivery systems. Consequently, the drug release pattern from the cement paste (fresh cement) is of high clinical interest. However, previous studies have commonly evaluated the drug release using pre-set cements only. Therefore, the aim of this work was to determine if the time elapsed from cement preparation un...

  13. Limestone reaction in calcium aluminate cement–calcium sulfate systems

    OpenAIRE

    Bizzozero, Julien; Scrivener, Karen

    2015-01-01

    This paper reports a study of ternary blends composed of calcium aluminate cement, calcium sulfate hemihydrate and limestone. Compressive strength tests and hydration kinetics were studied as a function of limestone and calcium sulfate content. The phase evolution and the total porosity were followed and compared to thermodynamic simulation to understand the reactions involved and the effect of limestone on these binders. The reaction of limestone leads to the formation of hemicarboaluminate ...

  14. Use of cement as lost-circulation material : best practices

    Energy Technology Data Exchange (ETDEWEB)

    Fidan, E. [Halliburton, Calgary, AB (Canada); Babadagli, T.; Kuru, E. [Alberta Univ., Edmonton, AB (Canada)

    2004-07-01

    One of the challenges facing oil well drilling operations is lost circulation, which refers to the partial or complete loss of drilling fluid or cement during drilling, circulation, running casing, or cementing operations. This problem can result in increased cost, loss of time, plugging of productive zones, blowouts, excessive water influx, and excessive formation caving. Lost circulation occurs in high-permeability zones such as highly fractured, vuggy or cavernous reservoirs when the hydrostatic pressure of drilling fluids is greater than the breaking strength of the formation. Cement is one of the common lost-circulation materials (LCMs). The use of proper cement composition and cementing techniques is important for successful cementing jobs. This paper presents solutions for 3 field cases from the Canada Western Sedimentary Basin where cement or drilling fluid loss has been a problem. Cement loss was minimized in two cases by using proper cement type and using optimum design during casing cementing. In another case, cement was used to cure drilling fluid loss. The various LCM applications described in this paper were: thixotropic and ultrathixotropic cement slurries; slurries containing cello flakes, mica and calcium carbonate for mechanical bridging; unique spacers and surfactant packages; and, foamed cement for controlling loss. 28 refs., 2 tabs., 2 figs.

  15. Microscale Investigation of Arsenic Distribution and Species in Cement Product from Cement Kiln Coprocessing Wastes

    Directory of Open Access Journals (Sweden)

    Yufei Yang

    2013-01-01

    Full Text Available To improve the understanding of the immobilization mechanism and the leaching risk of Arsenic (As in the cement product from coprocessing wastes using cement kiln, distribution and species of As in cement product were determined by microscale investigation methods, including electron probe microanalysis (EPMA and X-ray absorption spectroscopy. In this study, sodium arsenate crystals (Na3AsO412H2O were mixed with cement production raw materials and calcined to produce cement clinker. Then, clinker was mixed water to prepare cement paste. EPMA results showed that As was generally distributed throughout the cement paste. As content in calcium silicate hydrates gel (C-S-H was in low level, but higher than that in other cement mineral phases. This means that most of As is expected to form some compounds that disperse on the surfaces of cement mineral phases. Linear combination fitting (LCF of the X-ray absorption near edge structure spectra revealed that As in the cement paste was predominantly As(V and mainly existed as Mg3(AsO42, Ca3(AsO42, and Na2HAsO4.

  16. Heterogeneous Glasses and Sustainable Cement

    Science.gov (United States)

    Del Gado, Emanuela

    2015-03-01

    Calcium-silicate hydrate (C-S-H) is the main binding agent in cement and concrete. It forms at the beginning of cement hydration, it progressively densifies as cement hardens and is ultimately responsible for the performances of concrete. This hydration product is a cohesive nano-scale heterogeneous glass, whose structure and mechanics are still poorly understood, in spite of its practical importance. I will review some of the open questions for this fascinating material and discuss a statistical physics approach recently developed, which allows us to investigate the structural arrest and solidification under the out-of-equilibrium conditions typical of cement hydration and the role of the nano-scale structure in C-S-H mechanics upon hardening. Our approach unveils how some distinctive features of the kinetics of cement hydration can be related to changes in the morphology of this glassy material and elucidates the role of nano-scale mechanical heterogeneities in the hardened C-S-H.

  17. CEMENT SLURRIES FOR GEOTHERMAL WELLS CEMENTING

    Directory of Open Access Journals (Sweden)

    Nediljka Gaurina-Međimurec

    1994-12-01

    Full Text Available During a well cementing special place belongs to the cement slurry design. To ensure the best quality of cementing, a thorough understanding of well parameters is essential, as well as behaviour of cement slurry (especially at high temperatures and application of proven cementing techniques. Many cement jobs fail because of bad job planning. Well cementing without regarding what should be accomplished, can lead to well problems (channels in the cement, unwanted water, gas or fluid production, pipe corrosion and expensive well repairs. Cementing temperature conditions are important because bot-tomhole circulating temperatures affect slurry thickening time, arheology, set time and compressive strength development. Knowing the actual temperature which cement encounters during placement allows the selection of proper cementing materials for a specific application. Slurry design is affected by well depth, bottom hole circulating temperature and static temperature, type or drilling fluid, slurry density, pumping time, quality of mix water, fluid loss control, flow regime, settling and free water, quality of cement, dry or liquid additives, strength development, and quality of the lab cement testing and equipment. Most Portland cements and Class J cement have shown suitable performances in geot-hermal wells. Cement system designs for geothermal wells differ from those for conventional high temperature oil and gas wells in the exclusive use of silica flour instead of silica sand, and the avoidance of fly ash as an extender. In this paper, Portland cement behaviour at high temperatures is described. Cement slurry and set cement properties are also described. Published in literature, the composition of cement slurries which were tested in geothermal conditions and which obtained required compressive strength and water permeability are listed. As a case of our practice geothermal wells Velika Ciglena-1 and Velika Ciglena-la are described.

  18. Cinética de hidratação de ligantes à base de alumina hidratável ou aluminato de cálcio Kinetics of hydration of binders based on hydratable alumina or calcium aluminate cement

    Directory of Open Access Journals (Sweden)

    I. R. Oliveira

    2007-03-01

    Full Text Available O estado de dispersão da matriz de um concreto refratário apresenta uma grande influência no comportamento reológico desse material, determinando as técnicas utilizadas para a sua aplicação. Tais métodos normalmente exigem a preparação de concretos com elevada fluidez, que possam ser bombeados com facilidade e sejam capazes de preencher moldes de formato complexo sem a necessidade de aplicação de vibração. Entretanto, embora tais requisitos favoreçam uma boa trabalhabilidade do concreto, tendem a aumentar o tempo requerido para efetuar a desmoldagem do corpo conformado. Uma vez que o desenvolvimento da resistência mecânica do concreto está intimamente relacionado ao processo de hidratação do ligante hidráulico, este necessita ser controlado quando se busca a redução do tempo para a desmoldagem. Tal controle depende de um profundo conhecimento das variáveis que determinam a cinética das reações. Neste contexto, o objetivo deste trabalho foi o de avaliar a influência do tipo de ligante hidráulico, da temperatura e da presença de finos (matriz ou de aditivos inorgânicos adicionados ao concreto sobre o processo de hidratação por meio de medidas de temperatura e ensaios reológicos oscilatórios em função do tempo.The dispersion of refractory castables matrix presents a great influence on their rheological behavior, which defines the most appropriate methods for placing these materials. The growing demand for automatically transported refractory castables has promoted the use of pumpable castables, usually specified as self flow compositions. Nevertheless, castables with higher fluidity present longer workability, leading to extended demoulding times. Because the strength development is intimately linked to the hydration process of calcium aluminate cement or hydratable alumina, it needs to be controlled in order to reach the minimum time for demoulding, contributing to reducing overall costs. The control of cement

  19. Development of hydroxyapatite bone cement for controlled drug ...

    Indian Academy of Sciences (India)

    The purpose of this work was to study the preparation and characterization of drug–hydroxyapatite cement. The hydroxyapatite (HA) cement has been synthesized by using tricalcium phosphate, calcium carbonate and dicalcium phosphate anhydrous with sodium hydrogen phosphate as liquid phase. The effect of added ...

  20. Factors Affecting Cement Paste When Used As A Binding Agent ...

    African Journals Online (AJOL)

    The study revealed that cement is affected by calcium chloride, chloride suphate, magnesium and sodium salt. These chemicals attack and destroy the binding power of cement. “If a salt looses its savour, how shall it be salted? It is therefore good for nothing but to be cast out and to be trodden under foot of men” – Mathew ...

  1. ADVANCED CEMENTS FOR GEOTHERMAL WELLS

    Energy Technology Data Exchange (ETDEWEB)

    SUGAMA,T.

    2007-01-01

    Using the conventional well cements consisting of the calcium silicate hydrates (CaO-SiO{sub 2}-H{sub 2}O system) and calcium aluminum silicate hydrates (CaO-Al{sub 2}O{sub 3}-SiO{sub 2}-H{sub 2}O system) for the integrity of geothermal wells, the serious concern confronting the cementing industries was their poor performance in mechanically supporting the metallic well casing pipes and in mitigating the pipe's corrosion in very harsh geothermal reservoirs. These difficulties are particularly acute in two geological regions: One is the deep hot downhole area ({approx} 1700 m depth at temperatures of {approx} 320 C) that contains hyper saline water with high concentrations of CO{sub 2} (> 40,000 ppm) in conjunction with {approx} 100 ppm H{sub 2}S at a mild acid of pH {approx} 5.0; the other is the upper well region between the well's surface and {approx} 1000 m depth at temperatures up to 200 C. The specific environment of the latter region is characterized by highly concentrated H{sub 2}SO{sub 4} (pH < 1.5) brine containing at least 5000 ppm CO{sub 2}. When these conventional cements are emplaced in these harsh environments, their major shortcoming is their susceptibility to reactions with hot CO{sub 2} and H{sub 2}SO4, thereby causing their deterioration brought about by CO{sub 2}-catalyzed carbonation and acid-initiated erosion. Such degradation not only reduced rapidly the strength of cements, lowering the mechanical support of casing pipes, but also increased the extent of permeability of the brine through the cement layer, promoting the rate of the pipe's corrosion. Severely carbonated and acid eroded cements often impaired the integrity of a well in less than one year; in the worst cases, casings have collapsed within three months, leading to the need for costly and time-consuming repairs or redrilling operations. These were the reasons why the geothermal well drilling and cementing industries were concerned about using conventional well

  2. Microstructure characteristics of cement-stabilized sandy soil using nanosilica

    Directory of Open Access Journals (Sweden)

    Asskar Janalizadeh Choobbasti

    2017-10-01

    Full Text Available An experimental program was conducted to explore the impact of nanosilica on the microstructure and mechanical characteristics of cemented sandy soil. Cement agent included Portland cement type II. Cement content was 6% by weight of the sandy soil. Nanosilica was added in percentages of 0%, 4%, 8% and 12% by weight of cement. Cylindrical samples were prepared with relative density of 80% and optimum water content and cured for 7 d, 28 d and 90 d. Microstructure characteristics of cement-nanosilica-sand mixtures after 90 d of curing have been explored using atomic force microscopy (AFM, scanning electron microscopy (SEM and X-ray diffraction (XRD tests. Effects of curing time on microstructure properties of cemented sandy soil samples with 0% and 8% nanosilica have been investigated using SEM test. Unconfined compression test (for all curing times and compaction test were also performed. The SEM and AFM tests results showed that nanosilica contributes to enhancement of cemented sandy soil through yielding denser, more uniform structure. The XRD test demonstrated that the inclusion of nanosilica in the cemented soil increases the intensity of the calcium silicate hydrate (CSH peak and decreases the intensity of the calcium hydroxide (CH peak. The results showed that adding optimum percentages of nanosilica to cement-stabilized sandy soil enhances its mechanical and microstructure properties.

  3. Ion release and pH of a new endodontic cement, MTA and Portland cement

    OpenAIRE

    Amini Ghazvini, Sara; Abdo Tabrizi, Maryam; Kobarfard, Farzad; Akbarzadeh Baghban, Alireza; Asgary, Saeed

    2009-01-01

    INTRODUCTION: This in vitro study measured and compared pH and phosphate and calcium ions release of a new endodontic material (CEM cement), mineral trioxide aggregate (MTA), and Portland cement (PC) using UV-visible technique, atomic absorption spectrophotometry methods, and pH meter, respectively. MATERIALS AND METHODS: Each material was placed in a plastic tube (n=10) and immersed in a glass flask containing deionized water. Half of the samples were tested for determining pH and released i...

  4. PROPERTIES OF CEMENT PASTE AND CONCRETE CONTAINING ...

    African Journals Online (AJOL)

    This paper assessed the effect of calcium carbide waste (CCW) as additive on the properties of cement paste and concrete. The CCW used was sourced from a local panel beating workshop. It was sundried and sieved through a 75 µm sieve and characterized by X-Ray Fluorescence (XRF) analytical method.

  5. Low pH Cements

    Energy Technology Data Exchange (ETDEWEB)

    Savage, David; Benbow, Steven [Quintessa Ltd., Henley-on-Thames (United Kingdom)

    2007-05-15

    The development of low-pH cements for use in geological repositories for radioactive waste stems from concerns over the potential for deleterious effects upon the host rock and other EBS materials (notably bentonite) under the hyperalkaline conditions (pH > 12) of cement pore fluids. Low pH cement (also known as low heat cement) was developed by the cement industry for use where large masses of cement (e.g. dams) could cause problems regarding heat generated during curing. In low pH cements, the amount of cement is reduced by substitution of materials such as fly ash, blast furnace slag, silica fume, and/or non-pozzolanic silica flour. SKB and Posiva have ruled out the use of blast furnace slag and fly-ash and are focusing on silica fume as a blending agent. Currently, no preferred composition has been identified by these agencies. SKB and Posiva have defined a pH limit {<=} 11 for cement grout leachates. To attain this pH, blending agents must comprise at least 50 wt % of dry materials. Because low pH cement has little, or no free portlandite, the cement consists predominantly of calcium silicate hydrate (CSH) gel with a Ca/Si ratio {<=} 0.8. Although there are potential implications for the performance of the spent fuel and cladding due to the presence of hyperalkaline fluids from cement, the principal focus for safety assessment lies with the behaviour of bentonite. There are a number of potential constraints on the interaction of hyperalkaline cement pore fluids with bentonite, including mass balance, thermodynamic issues, mass transport, and kinetics, but none of these is likely to be limiting if conventional OPC cements are employed in repository construction. Nevertheless: Low-pH cements may supply approximately 50 % less hydroxyl ions than conventional OPC for a given volume of cement, but mass balance constraints are complicated by the uncertainty concerning the type of secondary minerals produced during cement-bentonite interaction. The change of aqueous

  6. Combined delivery of bone morphogenetic protein-2 and insulin-like growth factor-1 from nano-poly (γ-glutamic acid)/β-tricalcium phosphate-based calcium phosphate cement and its effect on bone regeneration in vitro.

    Science.gov (United States)

    Shu, Xiulin; Feng, Jin; Feng, Jing; Huang, Xiaomo; Li, Liangqiu; Shi, Qingshan

    2017-11-01

    In this study, nano-doped calcium phosphate cement delivery systems (poly (γ-glutamic acid)/β-tricalcium phosphate/calcium phosphate ceramics and nano (γ-glutamic acid)/β-tricalcium phosphate/calcium phosphate ceramic) were fabricated, and low doses (10 µg/g) of two growth factors, insulin-like growth factor-1 and bone morphogenetic protein-2, were encapsulated then sequentially released. We characterized the delivery systems using Fourier transform infrared spectroscopy and X-ray diffraction and measured washout resistance and compressive strength, and thus optimized the most appropriate proportioning of delivery systems for the two growth factors. One of the growth factors was absorbed by the nano-poly (γ-glutamic acid)/β-tricalcium phosphate, which was then mixed into the calcium phosphate ceramic solid phase to create a new solid phase calcium phosphate ceramic. Nano-poly (γ-glutamic acid)/β-tricalcium phosphate/calcium phosphate ceramic carriers were then prepared by blending the new calcium phosphate ceramic solid phase powder with a solution of the remaining growth factor. The effects of different release patterns (studying sequential behavior) of insulin-like growth factor-1 and bone morphogenetic protein-2 on osteogenic proliferation and differentiation of the MC3t3-E1 mouse osteoblast cell were investigated. This combinational delivery system provided a controlled release of the two growth factors, in which nano-doping significantly affected their release kinetics. The incorporation of dual growth factors could potentially stimulate bone healing and promoting bone ingrowth processes at a low dose.

  7. Development of an Improved Cement for Geothermal Wells

    Energy Technology Data Exchange (ETDEWEB)

    Trabits, George [Trabits Group, LLC, Wasilla, AK (United States)

    2015-04-20

    After an oil, gas, or geothermal production well has been drilled, the well must be stabilized with a casing (sections of steel pipe that are joined together) in order to prevent the walls of the well from collapsing. The gap between the casing and the walls of the well is filled with cement, which locks the casing into place. The casing and cementing of geothermal wells is complicated by the harsh conditions of high temperature, high pressure, and a chemical environment (brines with high concentrations of carbon dioxide and sulfuric acid) that degrades conventional Portland cement. During the 1990s and early 2000s, the U.S. Department of Energy’s Geothermal Technologies Office (GTO) provided support for the development of fly-ash-modified calcium aluminate phosphate (CaP) cement, which offers improved resistance to degradation compared with conventional cement. However, the use of CaP cements involves some operational constraints that can increase the cost and complexity of well cementing. In some cases, CaP cements are incompatible with chemical additives that are commonly used to adjust cement setting time. Care must also be taken to ensure that CaP cements do not become contaminated with leftover conventional cement in pumping equipment used in conventional well cementing. With assistance from GTO, Trabits Group, LLC has developed a zeolite-containing cement that performs well in harsh geothermal conditions (thermal stability at temperatures of up to 300°C and resistance to carbonation) and is easy to use (can be easily adjusted with additives and eliminates the need to “sterilize” pumping equipment as with CaP cements). This combination of properties reduces the complexity/cost of well cementing, which will help enable the widespread development of geothermal energy in the United States.

  8. The suitability of a supersulfated cement for nuclear waste immobilisation

    Energy Technology Data Exchange (ETDEWEB)

    Collier, N.C., E-mail: nick.collier@sheffield.ac.uk [Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom); Milestone, N.B. [Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom); Callaghan Innovation, 69 Gracefield Road, PO Box 31310, Lower Hutt 5040 (New Zealand); Gordon, L.E. [Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom); Geopolymer and Minerals Processing Group, Department of Chemical and Biomolecular Engineering, University of Melbourne, Parkville, Victoria 3010 (Australia); Ko, S.-C. [Holcim Technology Ltd, Hagenholzstrasse 85, CH-8050 Zurich (Switzerland)

    2014-09-15

    Highlights: • We investigate a supersulfated cement for use as a nuclear waste encapsulant. • High powder fineness requires a high water content to satisfy flow requirements. • Heat generation during hydration is similar to a control cement paste. • Typical hydration products are formed resulting in a high potential for waste ion immobilisation. • Paste pH and aluminium corrosion is less than in a control cement paste. - Abstract: Composite cements based on ordinary Portland cement are used in the UK as immobilisation matrices for low and intermediate level nuclear wastes. However, the high pore solution pH causes corrosion of some metallic wastes and undesirable expansive reactions, which has led to alternative cementing systems being examined. We have investigated the physical, chemical and microstructural properties of a supersulfated cement in order to determine its applicability for use in nuclear waste encapsulation. The hardened supersulfated cement paste appeared to have properties desirable for use in producing encapsulation matrices, but the high powder specific surface resulted in a matrix with high porosity. Ettringite and calcium silicate hydrate were the main phases formed in the hardened cement paste and anhydrite was present in excess. The maximum rate of heat output during hydration of the supersulfated cement paste was slightly higher than that of a 9:1 blastfurnace slag:ordinary Portland cement paste commonly used by the UK nuclear waste processing industry, although the total heat output of the supersulfated cement paste was lower. The pH was also significantly lower in the supersulfated cement paste. Aluminium hydroxide was formed on the surface of aluminium metal encapsulated in the cement paste and ettringite was detected between the aluminium hydroxide and the hardened cement paste.

  9. Development of nanosilica bonded monetite cement from egg shells

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Huan, E-mail: huanzhou@cczu.edu.cn [Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu (China); Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Luchini, Timothy J.F.; Boroujeni, Nariman Mansouri [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Agarwal, Anand K.; Goel, Vijay K. [Department of Bioengineering, The University of Toledo, Toledo, OH (United States); Bhaduri, Sarit B. [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Division of Dentistry, The University of Toledo, Toledo, OH (United States)

    2015-05-01

    This work represents further effort from our group in developing monetite based calcium phosphate cements (CPC). These cements start with a calcium phosphate powder (MW-CPC) that is manufactured using microwave irradiation. Due to the robustness of the cement production process, we report that the starting materials can be derived from egg shells, a waste product from the poultry industry. The CPC were prepared with MW-CPC and aqueous setting solution. Results showed that the CPC hardened after mixing powdered cement with water for about 12.5 ± 1 min. The compressive strength after 24 h of incubation was approximately 8.45 ± 1.29 MPa. In addition, adding colloidal nanosilica to CPC can accelerate the cement hardening (10 ± 1 min) process by about 2.5 min and improve compressive strength (20.16 ± 4.39 MPa), which is more than double the original strength. The interaction between nanosilica and CPC was monitored using an environmental scanning electron microscope (ESEM). While hardening, nanosilica can bond to the CPC crystal network for stabilization. The physical and biological studies performed on both cements suggest that they can potentially be used in orthopedics. - Highlights: • Cement raw powder is derived from egg shells. • A microwave assisted system is used for preparing monetite bone cement. • Colloidal silica is used to reinforce cement.

  10. Dentin-cement Interfacial Interaction

    Science.gov (United States)

    Atmeh, A.R.; Chong, E.Z.; Richard, G.; Festy, F.; Watson, T.F.

    2012-01-01

    The interfacial properties of a new calcium-silicate-based coronal restorative material (Biodentine™) and a glass-ionomer cement (GIC) with dentin have been studied by confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), micro-Raman spectroscopy, and two-photon auto-fluorescence and second-harmonic-generation (SHG) imaging. Results indicate the formation of tag-like structures alongside an interfacial layer called the “mineral infiltration zone”, where the alkaline caustic effect of the calcium silicate cement’s hydration products degrades the collagenous component of the interfacial dentin. This degradation leads to the formation of a porous structure which facilitates the permeation of high concentrations of Ca2+, OH-, and CO32- ions, leading to increased mineralization in this region. Comparison of the dentin-restorative interfaces shows that there is a dentin-mineral infiltration with the Biodentine, whereas polyacrylic and tartaric acids and their salts characterize the penetration of the GIC. A new type of interfacial interaction, “the mineral infiltration zone”, is suggested for these calcium-silicate-based cements. PMID:22436906

  11. ULTRA-LIGHTWEIGHT CEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Fred Sabins

    2002-07-30

    The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). This report includes results from laboratory testing of ULHS systems along with other lightweight cement systems, including foamed and sodium silicate slurries. During this project quarter, a comparison study of the three cement systems examined the effect that cement drillout has on the three cement systems. Testing to determine the effect of pressure cycling on the shear bond properties of the cement systems was also conducted. This report discusses testing that was performed to analyze the alkali-silica reactivity of ULHS in cement slurries.

  12. Biomineralization in metakaolin modified cement mortar to improve its strength with lowered cement content.

    Science.gov (United States)

    Li, Mengmeng; Zhu, Xuejiao; Mukherjee, Abhijit; Huang, Minsheng; Achal, Varenyam

    2017-05-05

    The role of industrial byproduct as supplementary cementitious material to partially replace cement has greatly contributed to sustainable environment. Metakaolin (MK), one of such byproduct, is widely used to partial replacement of cement; however, during cement replacement at high percentage, it may not be a good choice to improve the strength of concrete. Thus, in the present study, biocement, a product of microbially induced carbonate precipitation is utilized in MK-modified cement mortars to improve its compressive strength. Despite of cement replacement with MK as high as 50%, the presented technology improved compressive strength of mortars by 27%, which was still comparable to those mortars with 100% cement. The results proved that biomineralization could be effectively used in reducing cement content without compromising compressive strength of mortars. Biocementation also reduced the porosity of mortars at all ages. The process was characterized by SEM-EDS to observe bacterially-induced carbonate crystals and FTIR spectroscopy to predict responsible bonding in the formation of calcium carbonate. Further, XRD analysis identified bio/minerals formed in the MK-modified mortars. The study also encourages combining biological role in construction engineering to solve hazardous nature of cement and at same time solve the disposal problem of industrial waste for sustainable environment. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Comparison of percutaneous cannulated screw fixation and calcium sulfate cement grafting versus minimally invasive sinus tarsi approach and plate fixation for displaced intra-articular calcaneal fractures: a prospective randomized controlled trial.

    Science.gov (United States)

    Feng, Yongzeng; Shui, Xiaolong; Wang, Jianshun; Cai, Leyi; Yu, Yang; Ying, Xiaozhou; Kong, Jianzhong; Hong, Jianjun

    2016-07-15

    The management of displaced intra-articular calcaneal fractures (DIACFs) remains challenging and controversial. A prospective randomized controlled trial was conducted to compare percutaneous reduction, cannulated screw fixation and calcium sulfate cement (PR+CSC) grafting with minimally invasive sinus tarsi approach and plate fixation (MISTA) for treatment of DIACFs. Ultimately, 80 patients with a DIACFs were randomly allocated to receive either PR+CSC (N = 42) or MISTA (N = 38). Functional outcomes were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot scores. Radiological results were assessed using plain radiographs and computed tomography (CT) scans, and postoperative wound-related complications were also recorded. The average time from initial injury to operation and the average operation time in the PR+CSC group were both significantly shorter than those in the MISTA group (p < 0.05). There were significantly fewer complications in the PR+CSC group than those in the MISTA group (7.1 % vs 28.9 %, p < 0.001). The calcaneal width immediate postoperatively and at the final follow-up in the MISTA group were obviously improved compared to those in the PR+CSC group (p < 0.001). The variables of sagittal motion and hindfoot motion of the AOFAS scoring system in the PR+CSC group were significantly higher than those in the MISTA group (p < 0.05). The good and excellent results in the two groups were comparable for Sanders Type-II calcaneal fractures, but the good to excellent rate in the MISTA group was significantly higher for Sanders Type-III fractures (p < 0.05). The clinical outcomes are comparable between the two minimally invasive techniques in the treatment of Sanders Type-II DIACFs. The PR+CSC grafting is superior to the MISTA in terms of the average time between initial injury and operation, operation time, wound-related complications and subtalar joint activity. However, the MISTA has its own

  14. Cement-Based Materials for Nuclear Waste Storage

    CERN Document Server

    Cau-di-Coumes, Céline; Frizon, Fabien; Lorente, Sylvie

    2013-01-01

    As the re-emergence of nuclear power as an acceptable energy source on an international basis continues, the need for safe and reliable ways to dispose of radioactive waste becomes ever more critical. The ultimate goal for designing a predisposal waste-management system depends on producing waste containers suitable for storage, transportation and permanent disposal. Cement-Based Materials for Nuclear-Waste Storage provides a roadmap for the use of cementation as an applied technique for the treatment of low- and intermediate-level radioactive wastes.Coverage includes, but is not limited to, a comparison of cementation with other solidification techniques, advantages of calcium-silicate cements over other materials and a discussion of the long-term suitability and safety of waste packages as well as cement barriers. This book also: Discusses the formulation and production of cement waste forms for storing radioactive material Assesses the potential of emerging binders to improve the conditioning of problemati...

  15. Corrosion of aluminium metal in OPC- and CAC-based cement matrices

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, Hajime, E-mail: h.kinoshita@sheffield.ac.uk [Department of Materials Science and Engineering, The University of Sheffield, Mappin Street, Sheffield, S1 3JD (United Kingdom); Swift, Paul; Utton, Claire [Department of Materials Science and Engineering, The University of Sheffield, Mappin Street, Sheffield, S1 3JD (United Kingdom); Carro-Mateo, Beatriz [The Public University of Navarra, C/Esquíroz, 30 trasera, Pamplona 31007 (Spain); Marchand, Geraldine [The National Institute of Applied Sciences (INSA) Lyon, 20 Avenue Albert Einstein 69621 Villeurbanne Cedex (France); Collier, Nick [National Nuclear Laboratory, Chadwick House, Birchwood Park, Warrington, WA3 6AE (United Kingdom); Milestone, Neil [Industrial Research Ltd., 69 Gracefield Road, Lower Hutt, 5040 (New Zealand)

    2013-08-15

    Corrosion of aluminium metal in ordinary Portland cement (OPC) based pastes produces hydrogen gas and expansive reaction products causing problems for the encapsulation of aluminium containing nuclear wastes. Although corrosion of aluminium in cements has been long known, the extent of aluminium corrosion in the cement matrices and effects of such reaction on the cement phases are not well established. The present study investigates the corrosion reaction of aluminium in OPC, OPC-blast furnace slag (BFS) and calcium aluminate cement (CAC) based systems. The total amount of aluminium able to corrode in an OPC and 4:1 BFS:OPC system was determined, and the correlation between the amount of calcium hydroxide in the system and the reaction of aluminium obtained. It was also shown that a CAC-based system could offer a potential matrix to incorporate aluminium metal with a further reduction of pH by introduction of phosphate, producing a calcium phosphate cement.

  16. Calcium - urine

    Science.gov (United States)

    Urinary Ca+2; Kidney stones - calcium in urine; Renal calculi - calcium in your urine; Parathyroid - calcium in urine ... Urine calcium level can help your provider: Decide on the best treatment for the most common type of kidney ...

  17. Properties of Cement Mortar Produced from Mixed Waste Materials with Pozzolanic Characteristics

    Science.gov (United States)

    Yen, Chi-Liang; Tseng, Dyi-Hwa; Wu, Yue-Ze

    2012-01-01

    Abstract Waste materials with pozzolanic characteristics, such as sewage sludge ash (SSA), coal combustion fly ash (FA), and granulated blast furnace slag (GBS), were reused as partial cement replacements for making cement mortar in this study. Experimental results revealed that with dual replacement of cement by SSA and GBS and triple replacement by SSA, FA, and GBS at 50% of total cement replacement, the compressive strength (Sc) of the blended cement mortars at 56 days was 93.7% and 92.9% of the control cement mortar, respectively. GBS had the highest strength activity index value and could produce large amounts of CaO to enhance the pozzolanic activity of SSA/FA and form calcium silicate hydrate gels to fill the capillary pores of the cement mortar. Consequently, the Sc development of cement mortar with GBS replacement was better than that without GBS, and the total pore volume of blended cement mortars with GBS/SSA replacement was less than that with FA/SSA replacement. In the cement mortar with modified SSA and GBS at 70% of total cement replacement, the Sc at 56 days was 92.4% of the control mortar. Modifying the content of calcium in SSA also increased its pozzolanic reaction. CaCl2 accelerated the pozzolanic activity of SSA better than lime did. Moreover, blending cement mortars with GBS/SSA replacement could generate more monosulfoaluminate to fill capillary pores. PMID:22783062

  18. Properties of Cement Mortar Produced from Mixed Waste Materials with Pozzolanic Characteristics.

    Science.gov (United States)

    Yen, Chi-Liang; Tseng, Dyi-Hwa; Wu, Yue-Ze

    2012-07-01

    Waste materials with pozzolanic characteristics, such as sewage sludge ash (SSA), coal combustion fly ash (FA), and granulated blast furnace slag (GBS), were reused as partial cement replacements for making cement mortar in this study. Experimental results revealed that with dual replacement of cement by SSA and GBS and triple replacement by SSA, FA, and GBS at 50% of total cement replacement, the compressive strength (Sc) of the blended cement mortars at 56 days was 93.7% and 92.9% of the control cement mortar, respectively. GBS had the highest strength activity index value and could produce large amounts of CaO to enhance the pozzolanic activity of SSA/FA and form calcium silicate hydrate gels to fill the capillary pores of the cement mortar. Consequently, the Sc development of cement mortar with GBS replacement was better than that without GBS, and the total pore volume of blended cement mortars with GBS/SSA replacement was less than that with FA/SSA replacement. In the cement mortar with modified SSA and GBS at 70% of total cement replacement, the Sc at 56 days was 92.4% of the control mortar. Modifying the content of calcium in SSA also increased its pozzolanic reaction. CaCl(2) accelerated the pozzolanic activity of SSA better than lime did. Moreover, blending cement mortars with GBS/SSA replacement could generate more monosulfoaluminate to fill capillary pores.

  19. Asphalt cement poisoning

    Science.gov (United States)

    ... petroleum material that hardens when it cools. Asphalt cement poisoning occurs when someone swallows asphalt. If hot ... found in: Road paving materials Roofing materials Tile cements Asphalt may also be used for other purposes.

  20. CHH Cement Composite

    Science.gov (United States)

    Cwirzen, A.; Habermehl-Cwirzen, K.; Nasibulina, L. I.; Shandakov, S. D.; Nasibulin, A. G.; Kauppinen, E. I.; Mudimela, P. R.; Penttala, V.

    The compressive strength and electrical resistivity for hardened pastes produced from nanomodified Portland SR cement (CHH- Carbon Hedge Hog cement) were studied. The nanomodification included growing of carbon nanotubes (CNTs) and carbon nanofibers (CNFs) on the cement particles. Pastes having water to binder ratio of 0.5 were produced. The obtained hardened material was characterized by increased compressive strength in comparison with the reference specimens made from pristine SR cement, which was attributed to reinforcing action of the CNTs and CNFs. The electrical resistivity of CHH composite was lower by one order of magnitude in comparison with reference Portland cement paste.

  1. ULTRA-LIGHTWEIGHT CEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Fred Sabins

    2001-04-15

    The objective of this project is to develop an improved ultra-lightweight cement using ultralight hollow glass spheres (ULHS). Work reported herein addresses Task 1: Assess Ultra-Lightweight Cementing Problems and Task 3: Test Ultra-Lightweight Cements. Results reported this quarter include a review and summary of Halliburton Energy Services (HES) and BJ Services historical performance data for lightweight cement applications. These data are analyzed and compared to ULHS cement and foamed cement performances. Similar data is expected from Schlumberger, and an analysis of this data will be completed in the following phases of the project. Quality control testing of materials used to formulate ULHS cements in the laboratory was completed to establish baseline material performance standards. A testing protocol was developed employing standard procedures as well as procedures tailored to evaluate ULHS and foamed cement. This protocol is presented and discussed. Results of further testing of ULHS cements are presented along with an analysis to establish cement performance design criteria to be used during the remainder of the project. Finally, a list of relevant literature on lightweight cement performance is compiled for review during the next quarter.

  2. Effect of provisional cements on shear bond strength of porcelain laminate veneers.

    Science.gov (United States)

    Altintas, Subutay Han; Tak, Onjen; Secilmis, Asli; Usumez, Aslihan

    2011-08-01

    The purpose of this study was to evaluate the effect of three provisional cements and two cleaning techniques on the final bond strength of porcelain laminate veneers. The occlusal third of the crowns of forty molar teeth were sectioned and embedded in autopolymerizing acrylic resin. Dentin surfaces were polished and specimens were randomly divided into four groups (n=10). Provisional restorations were fabricated and two provisional restorations were cemented onto each tooth. Restorations were fixed with one of three different provisional cements: eugenol-free provisional cement (Cavex), calcium hydroxide (Dycal), and light-cured provisional cement (Tempond Clear). Provisional restorations were removed with either a dental explorer and air-water spray, or a cleaning bur (Opticlean). In the control group, provisional restorations were not used on the surfaces of specimens. IPS Empress 2 ceramic discs were luted with a dual-cured resin cement (Panavia F). Shear bond strength was measured using a universal testing machine. Data were statistically analyzed by ANOVA, Tukey's HSD and Dunnett tests. Surfaces were examined by scanning electronic microscopy. Significant differences were found between the control group and both the light-cured provisional cement groups and the eugenol-free provisional cement-cleaning bur group (Pprovisional cement showed the lowest bond strength values. Selection of the provisional cement is an important factor in the ultimate bond strength of the final restoration. Calcium hydroxide provisional cement and cleaning with a dental explorer are advisable.

  3. The effects of calcium on the expression of genes involved in ...

    African Journals Online (AJOL)

    USER

    2010-06-14

    Jun 14, 2010 ... etiolated tomato seedlings (Zhang et al., 2002), delays fruit ripening (Ferguson, 1984), flower senescence and flower abscission (Glenn et al., 1988). Calcium, in the form of calcium pectate, binds adjacent cells and acts as a type of cementing agent within cell walls. Cementing is presumed to occur when ...

  4. Cement for Oil Well Cementing Operations in Ghana

    African Journals Online (AJOL)

    Michael

    with Imported Class 'G' Cement for Oil Well Cementing Operations in Ghana”, Ghana Mining Journal, Vol. ... to compare the physical properties of locally manufactured cement in Ghana with the class G cement. 2 Materials and Methods. 2.1 Materials. Three brands of .... Rheology of cement slurries is of great importance.

  5. Physical evaluation of a new pulp capping material developed from portland cement.

    Science.gov (United States)

    Negm, Ahmed; Hassanien, Ehab; Abu-Seida, Ashraf; Nagy, Mohamed

    2016-07-01

    This study examined the effects of addition of 10% and 25% by weight calcium hydroxide on the physicochemical properties of Portland cement associated with 20% bismuth oxide in order to develop a new pulp capping material. The solubility, pH value, setting time, compressive strength, and push out bond strength of modified Portland were evaluated and compared to those of mineral trioxide aggregate (MTA) and Portland cement containing 20% bismuth oxide. The statistical analysis was performed with ANOVA and Duncan's post-hoc test. The results show that the strength properties and push out bond strength of Portland cement were adversely affected by addition of calcium hydroxide especially with a ratio of 25 wt%, however, the setting time and pH were not affected. MTA showed a statistically significant lower setting time than other cements (P≤0.001). Portland cement with bismuth oxide and Port Cal I showed a statistically significant higher Push out Bond strength than MTA and Port Cal II (P=0.001). Taking the setting time, push out bond strength and pH value into account, addition of 10 wt% calcium hydroxide to Portland cement associated with 20% bismuth oxide produces a new pulp capping material with acceptable physical and adhesive properties. Further studies are recommended to test this cement biologically as a new pulp capping material. Calcium hydroxide, MTA, Portland cement, setting time, solubility, strength.

  6. ULTRA-LIGHTWEIGHT CEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Fred Sabins

    2001-01-15

    The objective of this project is to develop an improved ultra-lightweigh cement using ultralight hollow glass spheres (ULHS). Work reported herein addresses Task 1: Assess Ultra-Lightweight Cementing Problems, Task 2: Review Russian Ultra-Lightweight Cement Literature, and Task 3: Test Ultra-Lightweight Cements. Results reported this quarter include a review and summary surface pipe and intermediate casing cementing conditions historically encountered in the US and establishment of average design conditions for ULHS cements. Russian literature concerning development and use of ultra-lightweight cements employing either nitrogen or ULHS was reviewed, and a summary is presented. Quality control testing of materials used to formulate ULHS cements in the laboratory was conducted to establish baseline material performance standards. A testing protocol was developed employing standard procedures as well as procedures tailored to evaluate ULHS. This protocol is presented and discussed. finally, results of initial testing of ULHS cements is presented along with analysis to establish cement performance design criteria to be used during the remainder of the project.

  7. Calcium Carbonate

    Science.gov (United States)

    Calcium carbonate is a dietary supplement used when the amount of calcium taken in the diet is not ... for healthy bones, muscles, nervous system, and heart. Calcium carbonate also is used as an antacid to relieve ...

  8. Calcium supplements

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007477.htm Calcium supplements To use the sharing features on this page, please enable JavaScript. WHO SHOULD TAKE CALCIUM SUPPLEMENTS? Calcium is an important mineral for the ...

  9. The microstructure and surface morphology of radiopaque tricalcium silicate cement exposed to different curing conditions.

    Science.gov (United States)

    Formosa, L M; Mallia, B; Bull, T; Camilleri, J

    2012-05-01

    Tricalcium silicate is the major constituent phase in mineral trioxide aggregate (MTA). It is thus postulated that pure tricalcium silicate can replace the Portland cement component of MTA. The aim of this research was to evaluate the microstructure and surface characteristics of radiopaque tricalcium silicate cement exposed to different curing conditions namely at 100% humidity or immersed in either water or a simulated body fluid at 37°C. The materials under study included tricalcium silicate and Portland cements with and without the addition of bismuth oxide radiopacifier. Material characterization was performed on hydrated cements using a combination of scanning electron microscopy (SEM) with X-ray energy dispersive (EDX) analyses and X-ray diffraction (XRD) analyses. Surface morphology was further investigated using optical profilometry. Testing was performed on cements cured at 100% humidity or immersed in either water or Hank's balanced salt solution (HBSS) for 1 and 28 days at 37°C. In addition leachate analysis was performed by X-ray fluorescence of the storage solution. The pH of the storage solution was assessed. All the cements produced calcium silicate hydrate and calcium hydroxide on hydration. Tricalcium silicate showed a higher reaction rate than Portland cement and addition of bismuth oxide seemed to also increase the rate of reaction with more calcium silicate hydrate and calcium hydroxide being produced as demonstrated by SEM and XRD analysis and also by surface deposits viewed by the optical profilometer. Cement immersion in HBSS resulted in the deposition of calcium phosphate during the early stages following immersion and extensive calcification after 28 days. The pH of all storage solutions was alkaline. The immersion in distilled water resulted in a higher pH of the solution than when the cements were immersed in HBSS. Leachate analysis demonstrated high calcium levels in all cements tested with higher levels in tricalcium silicate and

  10. Preparation and Mechanical Properties of Graphene Oxide: Cement Nanocomposites

    Science.gov (United States)

    Babak, Fakhim; Abolfazl, Hassani; Alimorad, Rashidi; Parviz, Ghodousi

    2014-01-01

    We investigate the performance of graphene oxide (GO) in improving mechanical properties of cement composites. A polycarboxylate superplasticizer was used to improve the dispersion of GO flakes in the cement. The mechanical strength of graphene-cement nanocomposites containing 0.1–2 wt% GO and 0.5 wt% superplasticizer was measured and compared with that of cement prepared without GO. We found that the tensile strength of the cement mortar increased with GO content, reaching 1.5%, a 48% increase in tensile strength. Ultra high-resolution field emission scanning electron microscopy (FE-SEM) used to observe the fracture surface of samples containing 1.5 wt% GO indicated that the nano-GO flakes were well dispersed in the matrix, and no aggregates were observed. FE-SEM observation also revealed good bonding between the GO surfaces and the surrounding cement matrix. In addition, XRD diffraction data showed growth of the calcium silicate hydrates (C-S-H) gels in GO cement mortar compared with the normal cement mortar. PMID:24574878

  11. Preparation and Mechanical Properties of Graphene Oxide: Cement Nanocomposites

    Directory of Open Access Journals (Sweden)

    Fakhim Babak

    2014-01-01

    Full Text Available We investigate the performance of graphene oxide (GO in improving mechanical properties of cement composites. A polycarboxylate superplasticizer was used to improve the dispersion of GO flakes in the cement. The mechanical strength of graphene-cement nanocomposites containing 0.1–2 wt% GO and 0.5 wt% superplasticizer was measured and compared with that of cement prepared without GO. We found that the tensile strength of the cement mortar increased with GO content, reaching 1.5%, a 48% increase in tensile strength. Ultra high-resolution field emission scanning electron microscopy (FE-SEM used to observe the fracture surface of samples containing 1.5 wt% GO indicated that the nano-GO flakes were well dispersed in the matrix, and no aggregates were observed. FE-SEM observation also revealed good bonding between the GO surfaces and the surrounding cement matrix. In addition, XRD diffraction data showed growth of the calcium silicate hydrates (C-S-H gels in GO cement mortar compared with the normal cement mortar.

  12. Bone cements for percutaneous vertebroplasty and balloon kyphoplasty: Current status and future developments

    Directory of Open Access Journals (Sweden)

    Zhiwei He

    2015-01-01

    Full Text Available Osteoporotic vertebral compression fractures (OVCFs have gradually evolved into a serious health care problem globally. In order to reduce the morbidity of OVCF patients and improve their life quality, two minimally invasive surgery procedures, vertebroplasty (VP and balloon kyphoplasty (BKP, have been developed. Both VP and BKP require the injection of bone cement into the vertebrae of patients to stabilize fractured vertebra. As such, bone cement as the filling material plays an essential role in the effectiveness of these treatments. In this review article, we summarize the bone cements that are currently available in the market and those still under development. Two major categories of bone cements, nondegradable acrylic bone cements (ABCs and degradable calcium phosphate cements (CPCs, are introduced in detail. We also provide our perspectives on the future development of bone cements for VP and BKP.

  13. [Biocompatibility of polymer-bioglass cement Cortoss®: in vitro test with the MG63 cell model].

    Science.gov (United States)

    Fölsch, C; Pinkernell, R; Stiletto, R

    2013-03-01

    Polymethylmethacrylate (PMMA) cement has been used for fixation of joint replacements for more than 50 years and cement augmentation of vertebrae has become a popular procedure since the first description in 1987. New cements have now been developed which are better suited to the requirements of minimally invasive application techniques for vertebral bodies. The combination of good mechanical properties and biocompatibility is the concern of present research. This study compared the features of a polymer-bioglass cement with a calcium phosphate cement used for vertebral augmentation. The human osteoblast-like cell culture MG63 was used to study the polymer-glass ceramic cement Cortoss® and the hydroxyapatite cement Kyphos®. Every 24 h for 5-6 days a defined volume of the culture medium was harvested in the presence of the bone cements and added to 16 cell cultures for each time period. The viability of cells was determined photometrically at 550 nm with the MTT assay and cell morphology was studied using light and electron microscopy. In the presence of the calcium phosphate cement an early and small reduction of cell activity was found compared with the controls. At the end of 1 week the viability parameter improved nearly reaching the control level. Electron microscopy showed crystals with a 3-dimensional shape. The cell cultures with Cortoss® showed no cellular activity and the microscopic examinations were negative. This effect was not different at days 1-5 after polymerization of the cement. The calcium phosphate cement studied showed a good biocompatibility and allowed morphological signs of apatite formation. At least within the first 5 days the polymer-glass ceramic cement showed a reasonable cytotoxic effect. There was no sign of recovery of cell function within that period. The biocompatibility of the polymer-glass ceramic cement appeared significantly worse compared with the calcium phosphate cement. An ideal composition of biomechanical properties

  14. Advantages of using glycolic acid as a retardant in a brushite forming cement.

    Science.gov (United States)

    Mariño, Faleh Tamimi; Torres, Jesús; Hamdan, Mohammad; Rodríguez, Carmen Rueda; Cabarcos, Enrique López

    2007-11-01

    In this study we have compared the effect of using acetic, glycolic, and citric acids on the brushite cement setting reaction and the properties of the resultant cement. The cement solid phase was made by mixing beta-tricalcium phosphate (beta-TCP), monocalcium dihydrogen phosphate anhydrate (MCPA), and sodium pyrophosphate, whereas the cement liquid phase consisted of aqueous solutions of carboxy acids at concentrations ranging from 0.5 to 3.5M. Cements were prepared by mixing the solid phase with the liquid phase to form a workable paste. The cement setting time was longer for glycolic and citric acids. The best mechanical properties in dry environments were obtained using glycolic and citric acid liquid phases. In a wet environment at 37 degrees C, the cement set with glycolic acid was the strongest one. Brushite cement diametral tensile strength seems to be affected by the calcium-carboxyl phase produced in the setting reaction. The acceptable setting time and mechanical properties of cements set in glycolic acid solutions are attributed to the additional hydrophilic groups in the carboxylic acid and the low solubility in water of the calcium salt produced in the reaction. Moreover, at high concentrations, carboxylic acids add chemically to the cement matrix becoming reactants themselves.

  15. Lime kiln dust as a potential raw material in portland cement manufacturing

    Science.gov (United States)

    Miller, M. Michael; Callaghan, Robert M.

    2004-01-01

    In the United States, the manufacture of portland cement involves burning in a rotary kiln a finely ground proportional mix of raw materials. The raw material mix provides the required chemical combination of calcium, silicon, aluminum, iron, and small amounts of other ingredients. The majority of calcium is supplied in the form of calcium carbonate usually from limestone. Other sources including waste materials or byproducts from other industries can be used to supply calcium (or lime, CaO), provided they have sufficiently high CaO content, have low magnesia content (less than 5 percent), and are competitive with limestone in terms of cost and adequacy of supply. In the United States, the lime industry produces large amounts of lime kiln dust (LKD), which is collected by dust control systems. This LKD may be a supplemental source of calcium for cement plants, if the lime and cement plants are located near enough to each other to make the arrangement economical.

  16. Antagonist effects of calcium on borosilicate glass alteration

    Energy Technology Data Exchange (ETDEWEB)

    Mercado-Depierre, S. [CEA Marcoule, DTCD SPDE LCLT, 30207 Bagnols sur Cèze (France); Angeli, F., E-mail: frederic.angeli@cea.fr [CEA Marcoule, DTCD SPDE LCLT, 30207 Bagnols sur Cèze (France); Frizon, F. [CEA Marcoule, DTCD SECM LP2C, 30207 Bagnols sur Cèze (France); Gin, S. [CEA Marcoule, DTCD SPDE LCLT, 30207 Bagnols sur Cèze (France)

    2013-10-15

    Graphical abstract: Display Omitted -- Highlights: •Kinetic study of glass alteration is investigated in calcium-enriched solutions. •New insights into silicon–calcium interactions in glass/cement systems are proposed. •Glass alteration is controlled by pH, Ca concentration and reaction progress. •Evidence of antagonist effects according to the importance of these parameters. -- Abstract: Numerous studies have been conducted on glass and cement durability in contact with water, but very little work to date has focused directly on interactions between the two materials. These interactions are mostly controlled by silicon–calcium reactivity. However, the physical and chemical processes involved remain insufficiently understood to predict the evolution of coupled glass–cement systems used in several industrial applications. Results are reported from borosilicate glass alteration in calcium-rich solutions. Our data show that four distinct behaviors can be expected according to the relative importance of three key parameters: the pH, the reaction progress (short- or long-term alteration) and the calcium concentration. Glass alteration is thus controlled by specific mechanisms depending on the solution chemistry: calcium complexation at the glass surface, precipitation of calcium silicate hydrates (C–S–H) or calcium incorporation in the altered layer. These findings highlight the impact of silicon–calcium interactions on glass durability and open the way for a better understanding of glass–cement mixing in civil engineering applications as well as in nuclear waste storage.

  17. Development of nanosilica bonded monetite cement from egg shells.

    Science.gov (United States)

    Zhou, Huan; Luchini, Timothy J F; Boroujeni, Nariman Mansouri; Agarwal, Anand K; Goel, Vijay K; Bhaduri, Sarit B

    2015-05-01

    This work represents further effort from our group in developing monetite based calcium phosphate cements (CPC). These cements start with a calcium phosphate powder (MW-CPC) that is manufactured using microwave irradiation. Due to the robustness of the cement production process, we report that the starting materials can be derived from egg shells, a waste product from the poultry industry. The CPC were prepared with MW-CPC and aqueous setting solution. Results showed that the CPC hardened after mixing powdered cement with water for about 12.5±1 min. The compressive strength after 24h of incubation was approximately 8.45±1.29 MPa. In addition, adding colloidal nanosilica to CPC can accelerate the cement hardening (10±1 min) process by about 2.5 min and improve compressive strength (20.16±4.39 MPa), which is more than double the original strength. The interaction between nanosilica and CPC was monitored using an environmental scanning electron microscope (ESEM). While hardening, nanosilica can bond to the CPC crystal network for stabilization. The physical and biological studies performed on both cements suggest that they can potentially be used in orthopedics. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Ion release and pH of a new endodontic cement, MTA and Portland cement.

    Science.gov (United States)

    Amini Ghazvini, Sara; Abdo Tabrizi, Maryam; Kobarfard, Farzad; Akbarzadeh Baghban, Alireza; Asgary, Saeed

    2009-01-01

    This in vitro study measured and compared pH and phosphate and calcium ions release of a new endodontic material (CEM cement), mineral trioxide aggregate (MTA), and Portland cement (PC) using UV-visible technique, atomic absorption spectrophotometry methods, and pH meter, respectively. Each material was placed in a plastic tube (n=10) and immersed in a glass flask containing deionized water. Half of the samples were tested for determining pH and released ions after 1h, 3h, 24h, 48h, 7d and 28d. Remaining samples (n=5), were evaluated after 28d. Data was analyzed using one way ANOVA and Tukey tests. Results indicated that all materials were highly alkaline and released calcium and low concentration of phosphate ions in all the time intervals. CEM cement released considerably higher concentration of phosphate during the first hour (Pcalcium and phosphate. These conditions can stimulate the calcification process and explain the basic physico-chemical mechanisms of hard tissue regeneration of CEM cement.

  19. Carbon nanotubes cement composites

    OpenAIRE

    Simone Musso; Jean-Marc Tulliani; Giuseppe Ferro

    2011-01-01

    The present paper reviews the current state of the art of carbon nanotubes cement-based composites and the possible applications. The influence of carbon nanotubes additions onto cement paste mechanical and electrical properties are discussed in detail. Though promising, several challenges have still to be solved before the introduction of these new materials into the public sphere through civil infrastructures.

  20. ULTRA-LIGHTWEIGHT CEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Fred Sabins

    2002-01-23

    The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). This report includes results from laboratory testing of ULHS systems along with other lightweight cement systems: foamed and sodium silicate slurries. Comparison studies of the three cement systems examined several properties: tensile strength, Young's modulus, water permeability, and shear bond. Testing was also done to determine the effect that temperature cycling has on the shear bond properties of the cement systems. In addition, analysis was carried out to examine alkali silica reactivity of slurries containing ULHS. Data is also presented from a study investigating the effects of mixing and pump circulation on breakage of ULHS. Information is also presented about the field application of ULHS in cementing a 7-in. intermediate casing in south Texas.

  1. Investigation of an effervescent additive as porogenic agent for bone cement macroporosity.

    Science.gov (United States)

    Hesaraki, Saeed; Sharifi, Davood

    2007-01-01

    Calcium phosphate cements (CPCs) are biocompatible and osteoconductive materials used in dental, craniofacial and orthopaedic applications. One of the most important advantages of these materials is their replacement with bone followed by resorption. Already several attempts have been made to improve the resorption behaviour of calcium phosphate cements by increasing the porosity of the material. In this investigation a mixture of NaHCO(3) and citric acid monohydrate was added to the apatite cement component as an effervescent additive for producing interconnected macropores into the cement matrix. Mercury intrusion porosimetry was employed to determine pore volume and pore size distribution in the calcium phosphate cement (CPC) samples. Results showed that addition of only 10 wt % of the effervescent additive (based on the cement powder) to the CPC components lead to producing about 20 V % macropores (with the size of 10 to 1000 mum) into the cement structure. The setting time was measured in an incubator at 37 degrees C and decreased from 40 min for additive-free CPC to about 14 min for CPC containing effervescent additive. Other properties of the CPCs such as compressive strength, phase composition, microstructure morphology and dissolution behavior were evaluated after immersing them in a simulated body fluid solution. The results showed that the rate of formation of poor crystalline apatite phase have been improved by production of macroporosity into the cement matrix.

  2. Hydration characteristics and structure formation of cement pastes containing metakaolin

    Directory of Open Access Journals (Sweden)

    Dvorkin Leonid

    2018-01-01

    Full Text Available Metakaolin (MK is one of the most effective mineral admixtures for cement-based composites. The deposits of kaolin clays are wide-spread in the world. Metakaolin is comparable to silica fume as an active mineral admixture for cement-based composites. In this paper, the rheological and mechanical properties of cement paste containing metakaolin are investigated. The effect of MK is more evident at “tight” hydration conditions within mixtures with low water-cement ratio, provided by application of superplasticizers. The cement is replaced with 0 to 15% metakaolin, and superplasticizer content ranged from 0 to 1.5% by weight of cementitious materials (i.e. cement and metakaolin. An equation is derived to describe the relationship between the metakaolin and superplasticizer content and consistency of pastes. There is a linear dependence between metakalolin content and water demand. Second-degree polynomial describe the influence of superplasticizer content. The application of SP and MK may produce cement-water suspensions with water-retaining capacity at 50-70% higher than control suspensions. The investigation of initial structure forming of cement pastes with SP-MK composite admixture indicates the extension of coagulation structure forming phase comparing to the pastes without additives. Crystallization stage was characterized by more intensive strengthening of the paste with SP-MK admixture comparing to the paste without admixtures and paste with SP. Results on the porosity parameters for hardened cement paste indicate a decrease in the average diameter of pores and refinement of pore structure in the presence of metakaolin. A finer pore structure associated with an increase in strength. X-ray analysis data reveal a growing number of small-crystalline low-alkaline calcium hydrosilicates and reducing portlandite content, when MK dosage increases. Scanning electron microscopy (SEM data confirm, that hardened cement paste containing MK has

  3. Preparation and Characterization of Injectable Brushite Filled-Poly (Methyl Methacrylate) Bone Cement

    Science.gov (United States)

    Rodriguez, Lucas C.; Chari, Jonathan; Aghyarian, Shant; Gindri, Izabelle M.; Kosmopoulos, Victor; Rodrigues, Danieli C.

    2014-01-01

    Powder-liquid poly (methyl methacrylate) (PMMA) bone cements are widely utilized for augmentation of bone fractures and fixation of orthopedic implants. These cements typically have an abundance of beneficial qualities, however their lack of bioactivity allows for continued development. To enhance osseointegration and bioactivity, calcium phosphate cements prepared with hydroxyapatite, brushite or tricalcium phosphates have been introduced with rather unsuccessful results due to increased cement viscosity, poor handling and reduced mechanical performance. This has limited the use of such cements in applications requiring delivery through small cannulas and in load bearing. The goal of this study is to design an alternative cement system that can better accommodate calcium-phosphate additives while preserving cement rheological properties and performance. In the present work, a number of brushite-filled two-solution bone cements were prepared and characterized by studying their complex viscosity-versus-test frequency, extrusion stress, clumping tendency during injection through a syringe, extent of fill of a machined void in cortical bone analog specimens, and compressive strength. The addition of brushite into the two-solution cement formulations investigated did not affect the pseudoplastic behavior and handling properties of the materials as demonstrated by rheological experiments. Extrusion stress was observed to vary with brushite concentration with values lower or in the range of control PMMA-based cements. The materials were observed to completely fill pre-formed voids in bone analog specimens. Cement compressive strength was observed to decrease with increasing concentration of fillers; however, the materials exhibited high enough strength for consideration in load bearing applications. The results indicated that partially substituting the PMMA phase of the two-solution cement with brushite at a 40% by mass concentration provided the best combination of the

  4. Preparation and Characterization of Injectable Brushite Filled-Poly (Methyl Methacrylate Bone Cement

    Directory of Open Access Journals (Sweden)

    Lucas C. Rodriguez

    2014-09-01

    Full Text Available Powder-liquid poly (methyl methacrylate (PMMA bone cements are widely utilized for augmentation of bone fractures and fixation of orthopedic implants. These cements typically have an abundance of beneficial qualities, however their lack of bioactivity allows for continued development. To enhance osseointegration and bioactivity, calcium phosphate cements prepared with hydroxyapatite, brushite or tricalcium phosphates have been introduced with rather unsuccessful results due to increased cement viscosity, poor handling and reduced mechanical performance. This has limited the use of such cements in applications requiring delivery through small cannulas and in load bearing. The goal of this study is to design an alternative cement system that can better accommodate calcium-phosphate additives while preserving cement rheological properties and performance. In the present work, a number of brushite-filled two-solution bone cements were prepared and characterized by studying their complex viscosity-versus-test frequency, extrusion stress, clumping tendency during injection through a syringe, extent of fill of a machined void in cortical bone analog specimens, and compressive strength. The addition of brushite into the two-solution cement formulations investigated did not affect the pseudoplastic behavior and handling properties of the materials as demonstrated by rheological experiments. Extrusion stress was observed to vary with brushite concentration with values lower or in the range of control PMMA-based cements. The materials were observed to completely fill pre-formed voids in bone analog specimens. Cement compressive strength was observed to decrease with increasing concentration of fillers; however, the materials exhibited high enough strength for consideration in load bearing applications. The results indicated that partially substituting the PMMA phase of the two-solution cement with brushite at a 40% by mass concentration provided the best

  5. EVALUATION OF CHEMICALS INCORPORATED WOOD FIBRE CEMENT MATRIX PROPERTIES

    Directory of Open Access Journals (Sweden)

    MST. SADIA MAHZABIN

    2013-08-01

    Full Text Available Wood fibre cement (WFC boards are well established commercially and widely used in many developed countries. The combination of the properties of two important materials, i.e., cement, and previously treated fibrous materials like wood or agricultural residues; which made up the board, contributed in the performance of the board as building material. In this work, the WFC matrix (WFCM samples are produced to determine the physical properties of WFCM such as the density and water absorption. The wood fibres are incorporated/treated with three different chemical additives; calcium formate (Ca(HCOO2, sodium silicate (Na2.SiO3 and magnesium chloride (MgCl2 prior to mixing with cement. The mechanical properties of the WFCM, with or without chemicals treatment of fibres, such as the compressive strength and flexural strength are evaluated. Three wood/cement ratios (50:50, 40:60, 30:70 are used and the percentages of water and accelerator were 80% and 3% based on the cement weight, respectively. Three moisture-conditioned samples; accelerated aging, dry and wet conditions are used for flexural test. The results reveal that the wood/cement ratio, chemical additives and moisture content had a marked influence on the physical and mechanical properties of the matrix. Finally, it has been shown that the 40:60 wood/cement ratio samples with prior chemicals treatment of the fibres that undergo accelerated aging conditioning achieve higher strength then dry and wet-conditioned boards.

  6. Natural cement and stone restoration of Bourges Cathedral (France

    Directory of Open Access Journals (Sweden)

    C. Gosselin

    2008-01-01

    Full Text Available Natural cement, also called "Roman cement", was invented at the end of the 18th Century and played an important role in the development of civil engineering works until the 1860s. More surprisingly, it was also used to restore historic buildings, such as gothic cathedrals. This paper deals with the mineralogy and the durability of natural cement, in the particular case of the Bourges Cathedral in France. This study illustrates the interest of this material particularly adapted in stone repair or substitution. Contrary to traditional mortars, the present samples are made of neat cement paste, revealed by the absence of mineral additions as quartz or carbonate sand. Several combined techniques (SEM-EDS, TGA, XRD were carried out to determine the composition of the hydraulic binder rich in calcium aluminate hydrates. The raw marl at the origin of the cement production contains oxidized pyrites which consist in a potential source of sulphate pollution of the surrounding limestone. The exposition of the cement in urban environment leads to some weathering features as atmospheric sulphation. Finally a petrophysical approach, based on water porosity, capillary sorption and compressive strength, has been performed to demonstrate the durability and the compatibility of roman cement applied as a restoration mortar of historical building.

  7. Synthesis of belite cement from nano-silica extracted from two rice husk ashes.

    Science.gov (United States)

    Sinyoung, Suthatip; Kunchariyakun, Kittipong; Asavapisit, Suwimol; MacKenzie, Kenneth J D

    2017-04-01

    Nano-silicas extracted from a pure rice husk ash calcined in the laboratory (RHA) and ash from an impure industrial rice husk waste (BRHA), were used to form belite cement by firing with two different calcium sources (calcium carbonate and calcium nitrate). The nano-silica extracted from RHA was highly reactive due to its high pore volume and low activation energy of dehydration. The formation of belite cement from both nano-silicas was studied by firing with two different calcium sources, Ca(NO3)2 and CaCO3 at 800-1100 °C. Both nano-silicas formed the principal phase in belite cement (larnite or β-C2S) at temperatures as low as 800 °C, especially with calcium nitrate as the calcium source. Thus, highly impure BRHA is shown to be very suitable as a starting material for the low-temperature production of belite cement, especially in conjunction with calcium nitrate as the calcium source. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Removal of Oil Spills from Salt Water by Magnesium, Calcium ...

    African Journals Online (AJOL)

    Magnesium, calcium carbonates and oxides that are widely used in cement industries were employed in studying sorption of petroleum oil spills from salt water at different condition parameters such as temperature, loading weight, degree of salinity. Treatment of magnesium, calcium carbonates and oxides by dodecyl ...

  9. Tympanoplasty with ionomeric cement

    DEFF Research Database (Denmark)

    Kjeldsen, A D; Grøntved, A M

    2000-01-01

    with isolated erosion of the long incus process have been treated with a new surgical technique in which the ossicular chain was rebuilt with ionomeric cement. The results in hearing performance (mean pure-tone average (PTA) 0.5, 1 and 2 kHz) were evaluated pre- and post-surgery, and compared to those...... of > 10 dB, in 4 there was a slight improvement and in 2 a decline. The difference was not statistically significant. Hearing improvement using ionomeric cement in type II tympanoplasty was satisfactory. Reconstruction of the ossicular chain with ionomeric cement is recommended, as the procedure is easy...

  10. [Allergy towards bone cement].

    Science.gov (United States)

    Thomas, P; Schuh, A; Summer, B; Mazoochian, F; Thomsen, M

    2006-09-01

    Bone cements based on polymethylmethacrylate are typically used for fixation of artificial joints. Intolerance reactions to endoprostheses not explained by infection or mechanical failure may lead to allergological diagnostics, which mostly focuses on metal allergy. However, also bone cement components may provoke hypersensitivity reactions leading to eczema, implant loosening, or fistula formation. Elicitors of such reactions encompass acrylates and additives such as benzoyl peroxide, N,N-dimethyl-p-toluidine, hydroquinone, or antibiotics (particularly gentamicin). Upon repeated contact with bone cement components, e.g., acrylate monomers, also in medical personnel occasionally hand eczema or even asthma may develop. Therefore, in the case of suspected hypersensitivity reactions to arthroplasty, the allergological diagnostics should include bone cement components.

  11. In vitro bioactivity of a tricalcium silicate cement

    Energy Technology Data Exchange (ETDEWEB)

    Morejon-Alonso, L.; Bareiro, O.; Santos, L.A. dos, E-mail: loreley.morejon@ufrgs.b [Universidade Federal do Rio Grande do Sul (UFRG), Porto Alegre, RS (Brazil). Escola de Engenharia. Dep. de Materiais; Carrodeguas R, Garcia [Consejo Superior de Investigaciones Cientificas (CSIC), Madrid (Spain). Inst. de Ceramica y Vidrio. Dept. de Ceramica

    2009-07-01

    Tricalcium silicate is the major constituent of Portland cement and the responsible for their mechanical strength at early stages. In order to be used as and additive of conventional calcium phosphate cement (CPC), in vitro bioactivity of a calcium silicate cement (CSC) after soaking in simulated body fluid (SBF) for 14 days was study. The cement was obtained by mixing Ca{sub 3}SiO{sub 5}, obtained by sol-gel process, and a Na{sub 2}HPO{sub 4} solution. The morphological and structural changes of the material before and after soaking were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed the formation of a layer of a Hydroxyapatite (HA) onto the CSC cement after soaking for 1h in SBF that became denser with the increase of soaking time. The study suggests that Ca{sub 3}SiO{sub 5} would be an effective additive to improve the bioactivity and long term strength of conventional CPC. (author)

  12. The effect of water on the mechanical properties of soluble and insoluble ceramic cements.

    Science.gov (United States)

    Koh, Ilsoo; López, Alejandro; Pinar, Ana B; Helgason, Benedikt; Ferguson, Stephen J

    2015-11-01

    Ceramic cements are good candidates for the stabilization of fractured bone due to their potential ease of application and biological advantages. New formulations of ceramic cements have been tested for their mechanical properties, including strength, stiffness, toughness and durability. The changes in the mechanical properties of a soluble cement (calcium sulfate) upon water-saturation (saturation) was reported in our previous study, highlighting the need to test ceramic cements using saturated samples. It is not clear if the changes in the mechanical properties of ceramic cements are exclusive to soluble cements. Therefore the aim of the present study was to observe the changes in the mechanical properties of soluble and insoluble ceramic cements upon saturation. A cement with high solubility (calcium sulfate dihydrate, CSD) and a cement with low solubility (dicalcium phosphate dihydrate, DCPD) were tested. Three-point bending tests were performed on four different groups of: saturated CSD, non-saturated CSD, saturated DCPD, and non-saturated DCPD samples. X-ray diffraction analysis and scanning electron microscopy were also performed on a sample from each group. Flexural strength, effective flexural modulus and flexural strain at maximum stress, lattice volume, and crystal sizes and shape were compared, independently, between saturated and non-saturated groups of CSD and DCPD. Although material dissolution did not occur in all cases, all calculated mechanical properties decreased significantly in both CSD and DCPD upon saturation. The results indicate that the reductions in the mechanical properties of saturated ceramic cements are not dependent on the solubility of a ceramic cement. The outcome raised the importance of testing any implantable ceramic cements in saturated condition to estimate its in vivo mechanical properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Study on Utilization of Carboxyl Group Decorated Carbon Nanotubes and Carbonation Reaction for Improving Strengths and Microstructures of Cement Paste

    Directory of Open Access Journals (Sweden)

    Xiantong Yan

    2016-08-01

    Full Text Available Carbon nanotubes (CNTs have excellent mechanical properties and can be used to reinforce cement-based materials. On the other hand, the reaction product of carbonation with hydroxides in hydrated cement paste can reduce the porosity of cement-based materials. In this study, a novel method to improve the strength of cement paste was developed through a synergy of carbon nanotubes decorated with carboxyl group and carbonation reactions. The experimental results showed that the carboxyl group (–COOH of decorated carbon nanotubes and the surfactant can control the morphology of the calcium carbonate crystal of carbonation products in hydrated cement paste. The spindle-like calcium carbonate crystals showed great morphological differences from those observed in the conventional carbonation of cement paste. The spindle-like calcium carbonate crystals can serve as fiber-like reinforcements to reinforce the cement paste. By the synergy of the carbon nanotubes and carbonation reactions, the compressive and flexural strengths of cement paste were significantly improved and increased by 14% and 55%, respectively, when compared to those of plain cement paste.

  14. Preparation and in vivo evaluation of a silicate-based composite bone cement.

    Science.gov (United States)

    Ma, Bing; Huan, Zhiguang; Xu, Chen; Ma, Nan; Zhu, Haibo; Zhong, Jipin; Chang, Jiang

    2017-08-01

    Silicate-based cements have been developed as a class of bioactive and biodegradable bone cements owing to their good in vitro bioactivity and ability to dissolve in a simulated body fluid. Until recently, however, the in vivo evidence of their ability to support bone regeneration is still scarce. In the present study, a pilot in vivo evaluation of a silicate-based composite bone cement (CSC) was carried out in a rabbit femur defect model. The cement was composed of tricalcium silicate, 45S5 bioglass and calcium sulfate, and the self-setting properties of the material were established. The in vivo bone integration and biodegradability of CSC were investigated and compared with those of bioactive glass particulates, and a calcium phosphate cement. The results showed that CSC underwent a relatively slower in vivo degradation as compared with bioactive glass and calcium phosphate cement. Histological observation demonstrated that bone contact area at the interface between the surrounding bone and CSC gradually increased with time proceeding. CSC kept its structural integrity during implantation in vivo because of its acceptable mechanical strength. These results provide evidence of effectiveness in vivo and suggest potential clinical applications of the silicate-based composite bone cements.

  15. Changes in the drug release pattern of fresh and set simvastatin-loaded brushite cement.

    Science.gov (United States)

    Mestres, Gemma; Kugiejko, Karol; Pastorino, David; Unosson, Johanna; Öhman, Caroline; Karlsson Ott, Marjam; Ginebra, Maria-Pau; Persson, Cecilia

    2016-01-01

    Calcium phosphate cements are synthetic bone graft substitutes able to set at physiological conditions. They can be applied by minimally invasive surgery and can also be used as drug delivery systems. Consequently, the drug release pattern from the cement paste (fresh cement) is of high clinical interest. However, previous studies have commonly evaluated the drug release using pre-set cements only. Therefore, the aim of this work was to determine if the time elapsed from cement preparation until immersion in the solution (3 min for fresh cements, and 1h and 15 h for pre-set cements) had an influence on its physical properties, and correlating these to the drug release profile. Simvastatin was selected as a model drug, while brushite cement was used as drug carrier. This study quantified how the setting of a material reduces the accessibility of the release media to the material, thus preventing drug release. A shift in the drug release pattern was observed, from a burst-release for fresh cements to a sustained release for pre-set cements. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Hydrothermal Synthesis of Dicalcium Silicate Based Cement

    Science.gov (United States)

    Dutta, N.; Chatterjee, A.

    2017-06-01

    It is imperative to develop low energy alternative binders considering the large amounts of energy consumed as well as carbon dioxide emissions involved in the manufacturing of ordinary Portland cement. This study is on the synthesis of a dicalcium silicate based binder using a low temperature hydrothermal route.The process consists of synthesizing an intermediate product consisting of a calcium silicate hydrate phase with a Ca:Si ratio of 2:1 and further thermal treatment to produce the β-Ca2SiO4 (C2S) phase.Effect of various synthesis parameters like water to solid ratio, dwell time and temperature on the formation of the desired calcium silicate hydrate phase is reported along with effect of heating conditions for formation of the β-C2S phase. Around 77.45% of β-C2S phase was synthesized by thermal treatment of the intermediate phase at 820°C.

  17. The biomechanics of pedicle screw augmentation with cement.

    Science.gov (United States)

    Elder, Benjamin D; Lo, Sheng-Fu L; Holmes, Christina; Goodwin, Courtney R; Kosztowski, Thomas A; Lina, Ioan A; Locke, John E; Witham, Timothy F

    2015-06-01

    A persistent challenge in spine surgery is improving screw fixation in patients with poor bone quality. Augmenting pedicle screw fixation with cement appears to be a promising approach. The purpose of this study was to survey the literature and assess the previous biomechanical studies on pedicle screw augmentation with cement to provide in-depth discussions of the biomechanical benefits of multiple parameters in screw augmentation. This is a systematic literature review. A search of Medline was performed, combining search terms of pedicle screw, augmentation, vertebroplasty, kyphoplasty, polymethylmethacrylate, calcium phosphate, or calcium sulfate. The retrieved articles and their references were reviewed, and articles dealing with biomechanical testing were included in this article. Polymethylmethacrylate is an effective material for enhancing pedicle screw fixation in both osteoporosis and revision spine surgery models. Several other calcium ceramics also appear promising, although further work is needed in material development. Although fenestrated screw delivery appears to have some benefits, it results in similar screw fixation to prefilling the cement with a solid screw. Some differences in screw biomechanics were noted with varying cement volume and curing time, and some benefits from a kyphoplasty approach over a vertebroplasty approach have been noted. Additionally, in cadaveric models, cemented-augmented screws were able to be removed, albeit at higher extraction torques, without catastrophic damage to the vertebral body. However, there is a risk of cement extravasation leading to potentially neurological or cardiovascular complications with cement use. A major limitation of these reviewed studies is that biomechanical tests were generally performed at screw implantation or after a limited cyclic loading cycle; thus, the results may not be entirely clinically applicable. This is particularly true in the case of the bioactive calcium ceramics, as these

  18. Cement Pastes and Mortars Containing Nitrogen-Doped and Oxygen-Functionalized Multiwalled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Mauricio Martínez-Alanis

    2016-01-01

    Full Text Available Cement pastes and mortars based on ordinary Portland cement containing nitrogen-doped multiwalled carbon nanotubes (MWCNT-Nx or oxygen-functionalized multiwalled carbon nanotubes (MWCNT-Ox are investigated. To incorporate MWCNTs into the cementitious matrix, the as-produced carpets are dispersed over periods of 1 and 2 hours in distilled water at pH levels of 1 and 7. The cement pastes are prepared by adding 0.1 wt% of MWCNTs to cement powder, followed by characterization with SEM and X-ray diffraction (XRD at an early age (first hours of hydration. The mortars are mechanically characterized during the hydration process for a period of 28 days. SEM characterization of cement pastes revealed that the carbon nanotubes are well incorporated in the cementitious matrix, with the hydrated cement grains interconnected by long carbon nanotubes. XRD characterizations demonstrated that, during the hydration of cement pastes, different peaks emerged that were associated with ettringite, hydrated calcium silicate, and calcium hydroxide, among other structures. Results of the compressive strength measurements for mortars simultaneously mixed with MWCNT-Nx and MWCNT-Ox reached an increment of approximately 30% in compressive strength. In addition, density functional theory calculations were performed in nitrogen-doped and oxygen-functionalized carbon nanotubes interacting with a cement grain.

  19. Carbon Capture in the Cement Industry: Technologies, Progress, and Retrofitting.

    Science.gov (United States)

    Hills, Thomas; Leeson, Duncan; Florin, Nicholas; Fennell, Paul

    2016-01-05

    Several different carbon-capture technologies have been proposed for use in the cement industry. This paper reviews their attributes, the progress that has been made toward their commercialization, and the major challenges facing their retrofitting to existing cement plants. A technology readiness level (TRL) scale for carbon capture in the cement industry is developed. For application at cement plants, partial oxy-fuel combustion, amine scrubbing, and calcium looping are the most developed (TRL 6 being the pilot system demonstrated in relevant environment), followed by direct capture (TRL 4-5 being the component and system validation at lab-scale in a relevant environment) and full oxy-fuel combustion (TRL 4 being the component and system validation at lab-scale in a lab environment). Our review suggests that advancing to TRL 7 (demonstration in plant environment) seems to be a challenge for the industry, representing a major step up from TRL 6. The important attributes that a cement plant must have to be "carbon-capture ready" for each capture technology selection is evaluated. Common requirements are space around the preheater and precalciner section, access to CO2 transport infrastructure, and a retrofittable preheater tower. Evidence from the electricity generation sector suggests that carbon capture readiness is not always cost-effective. The similar durations of cement-plant renovation and capture-plant construction suggests that synchronizing these two actions may save considerable time and money.

  20. ULTRA-LIGHTWEIGHT CEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Fred Sabins

    2001-10-23

    The objective of this project is to develop an improved ultra-lightweight cement using ultra-lightweight hollow glass spheres (ULHS). Work reported herein addresses tasks performed in the fourth quarter as well as the other three quarters of the past year. The subjects that were covered in previous reports and that are also discussed in this report include: Analysis of field laboratory data of active cement applications from three oil-well service companies; Preliminary findings from a literature review focusing on problems associated with ultra-lightweight cements; Summary of pertinent information from Russian ultra-lightweight cement literature review; and Comparison of compressive strengths of ULHS systems using ultrasonic and crush methods Results reported from the fourth quarter include laboratory testing of ULHS systems along with other lightweight cement systems--foamed and sodium silicate slurries. These comparison studies were completed for two different densities (10.0 and 11.5 lb/gal) and three different field application scenarios. Additional testing included the mechanical properties of ULHS systems and other lightweight systems. Studies were also performed to examine the effect that circulation by centrifugal pump during mixing has on breakage of ULHS.

  1. Application of Calcium Phosphate Materials in Dentistry

    Directory of Open Access Journals (Sweden)

    Jabr S. Al-Sanabani

    2013-01-01

    Full Text Available Calcium phosphate materials are similar to bone in composition and in having bioactive and osteoconductive properties. Calcium phosphate materials in different forms, as cements, composites, and coatings, are used in many medical and dental applications. This paper reviews the applications of these materials in dentistry. It presents a brief history, dental applications, and methods for improving their mechanical properties. Notable research is highlighted regarding (1 application of calcium phosphate into various fields in dentistry; (2 improving mechanical properties of calcium phosphate; (3 biomimetic process and functionally graded materials. This paper deals with most common types of the calcium phosphate materials such as hydroxyapatite and tricalcium phosphate which are currently used in dental and medical fields.

  2. Effect of Provisional Cements on Shear Bond Strength of Porcelain Laminate Veneers

    Science.gov (United States)

    Altintas, Subutay Han; Tak, Onjen; Secilmis, Asli; Usumez, Aslihan

    2011-01-01

    Objectives: The purpose of this study was to evaluate the effect of three provisional cements and two cleaning techniques on the final bond strength of porcelain laminate veneers. Methods: The occlusal third of the crowns of forty molar teeth were sectioned and embedded in autopolymerizing acrylic resin. Dentin surfaces were polished and specimens were randomly divided into four groups (n=10). Provisional restorations were fabricated and two provisional restorations were cemented onto each tooth. Restorations were fixed with one of three different provisional cements: eugenol-free provisional cement (Cavex), calcium hydroxide (Dycal), and light-cured provisional cement (Tempond Clear). Provisional restorations were removed with either a dental explorer and air-water spray, or a cleaning bur (Opticlean). In the control group, provisional restorations were not used on the surfaces of specimens. IPS Empress 2 ceramic discs were luted with a dual-cured resin cement (Panavia F). Shear bond strength was measured using a universal testing machine. Data were statistically analyzed by ANOVA, Tukey’s HSD and Dunnett tests. Surfaces were examined by scanning electronic microscopy. Results: Significant differences were found between the control group and both the light-cured provisional cement groups and the eugenol-free provisional cement-cleaning bur group (P<.05). Groups that had received light-cured provisional cement showed the lowest bond strength values. Conclusions: Selection of the provisional cement is an important factor in the ultimate bond strength of the final restoration. Calcium hydroxide provisional cement and cleaning with a dental explorer are advisable. PMID:21912495

  3. A Novel Injectable Borate Bioactive Glass Cement as an Antibiotic Delivery Vehicle for Treating Osteomyelitis

    Science.gov (United States)

    Cui, Xu; Gu, Yi-Fei; Jia, Wei-Tao; Rahaman, Mohamed N.; Wang, Yang; Huang, Wen-Hai; Zhang, Chang-Qing

    2014-01-01

    Background A novel injectable cement composed of chitosan-bonded borate bioactive glass (BG) particles was evaluated as a carrier for local delivery of vancomycin in the treatment of osteomyelitis in a rabbit tibial model. Materials and Methods The setting time, injectability, and compressive strength of the borate BG cement, and the release profile of vancomycin from the cement were measured in vitro. The capacity of the vancomycin-loaded BG cement to eradicate methicillin-resistant Staphylococcus aureus (MRSA)-induced osteomyelitis in rabbit tibiae in vivo was evaluated and compared with that for a vancomycin-loaded calcium sulfate (CS) cement and for intravenous injection of vancomycin. Results The BG cement had an injectability of >90% during the first 3 minutes after mixing, hardened within 30 minutes and, after hardening, had a compressive strength of 18±2 MPa. Vancomycin was released from the BG cement into phosphate-buffered saline for up to 36 days, and the cumulative amount of vancomycin released was 86% of the amount initially loaded into the cement. In comparison, vancomycin was released from the CS cement for up 28 days and the cumulative amount released was 89%. Two months post-surgery, radiography and microbiological tests showed that the BG and CS cements had a better ability to eradicate osteomyelitis when compared to intravenous injection of vancomycin, but there was no significant difference between the BG and CS cements in eradicating the infection. Histological examination showed that the BG cement was biocompatible and had a good capacity for regenerating bone in the tibial defects. Conclusions These results indicate that borate BG cement is a promising material both as an injectable carrier for vancomycin in the eradication of osteomyelitis and as an osteoconductive matrix to regenerate bone after the infection is cured. PMID:24427311

  4. Optical cements for interferometric applications

    OpenAIRE

    Wimperis, J.R.; Johnston, Sean F.

    1984-01-01

    The wave front distortion introduced by optical cements\\ud is important in interferometric applications. We describe\\ud here tests performed to characterize two common cements,\\ud Epo-Tek 301 and Norland Optical Adhesive 61.

  5. Cement manufacture and the environment - Part I: Chemistry and technology

    Science.gov (United States)

    Van Oss, H. G.; Padovani, A.C.

    2002-01-01

    Hydraulic (chiefly portland) cement is the binding agent in concrete and mortar and thus a key component of a country's construction sector. Concrete is arguably the most abundant of all manufactured solid materials. Portland cement is made primarily from finely ground clinker, which itself is composed dominantly of hydraulically active calcium silicate minerals formed through high-temperature burning of limestone and other materials in a kiln. This process requires approximately 1.7 tons of raw materials perton of clinker produced and yields about 1 ton of carbon dioxide (CO2) emissions, of which calcination of limestone and the combustion of fuels each contribute about half. The overall level of CO2 output makes the cement industry one of the top two manufacturing industry sources of greenhouse gases; however, in many countries, the cement industry's contribution is a small fraction of that from fossil fuel combustion by power plants and motor vehicles. The nature of clinker and the enormous heat requirements of its manufacture allow the cement industry to consume a wide variety of waste raw materials and fuels, thus providing the opportunity to apply key concepts of industrial ecology, most notably the closing of loops through the use of by-products of other industries (industrial symbiosis). In this article, the chemistry and technology of cement manufacture are summarized. In a forthcoming companion article (part II), some of the environmental challenges and opportunities facing the cement industry are described. Because of the size and scope of the U.S. cement industry, the analysis relies primarily on data and practices from the United States.

  6. Antimicrobial activity of bone cements embedded with organic nanoparticles

    Science.gov (United States)

    Perni, Stefano; Thenault, Victorien; Abdo, Pauline; Margulis, Katrin; Magdassi, Shlomo; Prokopovich, Polina

    2015-01-01

    Infections after orthopedic surgery are a very unwelcome outcome; despite the widespread use of antibiotics, their incidence can be as high as 10%. This risk is likely to increase as antibiotics are gradually losing efficacy as a result of bacterial resistance; therefore, novel antimicrobial approaches are required. Parabens are a class of compounds whose antimicrobial activity is employed in many cosmetic and pharmaceutical products. We developed propylparaben nanoparticles that are hydrophilic, thus expanding the applicability of parabens to aqueous systems. In this paper we assess the possibility of employing paraben nanoparticles as antimicrobial compound in bone cements. The nanoparticles were embedded in various types of bone cement (poly(methyl methacrylate) [PMMA], hydroxyapatite, and brushite) and the antimicrobial activity was determined against common causes of postorthopedic surgery infections such as: Staphylococcus aureus, methicillin-resistant S. aureus, Staphylococcus epidermidis, and Acinetobacter baumannii. Nanoparticles at concentrations as low as 1% w/w in brushite bone cement were capable of preventing pathogens growth, 5% w/w was needed for hydroxyapatite bone cement, while 7% w/w was required for PMMA bone cement. No detrimental effect was determined by the addition of paraben nanoparticles on bone cement compression strength and cytocompatibility. Our results demonstrate that paraben nanoparticles can be encapsulated in bone cement, providing concentration-dependent antimicrobial activity; furthermore, lower concentrations are needed in calcium phosphate (brushite and hydroxyapatite) than in acrylic (PMMA) bone cements. These nanoparticles are effective against a wide spectrum of bacteria, including those already resistant to the antibiotics routinely employed in orthopedic applications, such as gentamicin. PMID:26487803

  7. Effect of Graphene Oxide (GO) on the Morphology and Microstructure of Cement Hydration Products

    Science.gov (United States)

    Zhang, Shupeng; Zheng, Dapeng; Yang, Haibin; Cui, Hongzhi; Li, Dongxu

    2017-01-01

    In this study, the effects of graphene oxide (GO) on the microstructure of cement mortars were studied using scanning electron microscopy (SEM), thermogravimetric (TG), and X-ray diffraction (XRD) techniques. Cement mortar samples with different proportions of GO (0.02, 0.04, 0.06, and 0.08 wt % based on the weight of cement) were prepared. The test results showed that GO affected the crystallization of cement hydration products, C–S–H (calcium silicate hydrate is the main hydrate product) and CH (calcium hydroxide). The morphology of hydration products changed with the increase of GO content. Furthermore, the results of XRD analyses showed that the diffraction peak intensity and the crystal grain size of CH (001), (100), (101), and (102) for GO samples increased considerably compared with the control sample. Based on the results, it can be understood that GO can modify the crystal surface of CH, leading to the formation of larger crystals. PMID:29206157

  8. Effect of Graphene Oxide (GO on the Morphology and Microstructure of Cement Hydration Products

    Directory of Open Access Journals (Sweden)

    Liguo Wang

    2017-12-01

    Full Text Available In this study, the effects of graphene oxide (GO on the microstructure of cement mortars were studied using scanning electron microscopy (SEM, thermogravimetric (TG, and X-ray diffraction (XRD techniques. Cement mortar samples with different proportions of GO (0.02, 0.04, 0.06, and 0.08 wt % based on the weight of cement were prepared. The test results showed that GO affected the crystallization of cement hydration products, C–S–H (calcium silicate hydrate is the main hydrate product and CH (calcium hydroxide. The morphology of hydration products changed with the increase of GO content. Furthermore, the results of XRD analyses showed that the diffraction peak intensity and the crystal grain size of CH (001, (100, (101, and (102 for GO samples increased considerably compared with the control sample. Based on the results, it can be understood that GO can modify the crystal surface of CH, leading to the formation of larger crystals.

  9. Investigation of the hydration and bioactivity of radiopacified tricalcium silicate cement, Biodentine and MTA Angelus.

    Science.gov (United States)

    Camilleri, Josette; Sorrentino, François; Damidot, Denis

    2013-05-01

    Novel root-end filling materials are composed of tricalcium silicate (TCS) and radiopacifier as opposed to the traditional mineral trioxide aggregate (MTA) which is made up of clinker derived from Portland cement and bismuth oxide. The aim of this research was to characterize and investigate the hydration of a tricalcium silicate-based proprietary brand cement (Biodentine™) and a laboratory manufactured cement made with a mixture of tricalcium silicate and zirconium oxide (TCS-20-Z) and compare their properties to MTA Angelus™. The materials investigated included a cement containing 80% of TCS and 20% zirconium oxide (TCS-20-Z), Biodentine™ and MTA Angelus™. The specific surface area and the particle size distribution of the un-hydrated cements and zirconium oxide were investigated using a gas adsorption method and scanning electron microscopy. Un-hydrated cements and set materials were tested for mineralogy and microstructure, assessment of bioactivity and hydration. Scanning electron microscopy, X-ray energy dispersive analysis, X-ray fluorescence spectroscopy, X-ray diffraction, Rietveld refined X-ray diffraction and calorimetry were employed. The radiopacity of the materials was investigated using ISO 6876 methods. The un-hydrated cements were composed of tricalcium silicate and a radiopacifier phase; zirconium oxide for both Biodentine™ and TCS-20-Z whereas bismuth oxide for MTA Angelus™. In addition Biodentine™ contained calcium carbonate particles and MTA Angelus™ exhibited the presence of dicalcium silicate, tricalcium aluminate, calcium, aluminum and silicon oxides. TCS and MTA Angelus™ exhibited similar specific surface area while Biodentine™ had a greater specific surface area. The cements hydrated and produced some hydrates located either as reaction rim around the tricalcium silicate grain or in between the grains at the expense of volume containing the water initially present in the mixture. The rate of reaction of tricalcium

  10. Efficacy of the biomaterials 3wt%-nanostrontium-hydroxyapatite-enhanced calcium phosphate cement (nanoSr-CPC) and nanoSr-CPC-incorporated simvastatin-loaded poly(lactic-co-glycolic-acid) microspheres in osteogenesis improvement: An explorative multi-phase experimental in vitro/vivo study.

    Science.gov (United States)

    Masaeli, Reza; Jafarzadeh Kashi, Tahereh Sadat; Dinarvand, Rassoul; Rakhshan, Vahid; Shahoon, Hossein; Hooshmand, Behzad; Mashhadi Abbas, Fatemeh; Raz, Majid; Rajabnejad, Alireza; Eslami, Hossein; Khoshroo, Kimia; Tahriri, Mohammadreza; Tayebi, Lobat

    2016-12-01

    The purpose of this multi-phase explorative in vivo animal/surgical and in vitro multi-test experimental study was to (1) create a 3wt%-nanostrontium hydroxyapatite-enhanced calcium phosphate cement (Sr-HA/CPC) for increasing bone formation and (2) creating a simvastatin-loaded poly(lactic-co-glycolic acid) (SIM-loaded PLGA) microspheres plus CPC composite (SIM-loaded PLGA+nanostrontium-CPC). The third goal was the extensive assessment of multiple in vitro and in vivo characteristics of the above experimental explorative products in vitro and in vivo (animal and surgical studies). Physical and chemical properties of the prepared Sr-HA/CPC were evaluated. MTT assay and alkaline phosphatase activities, and radiological and histological examinations of Sr-HA/CPC, CPC and negative control were compared. X-ray diffraction (XRD) indicated that crystallinity of the prepared cement increased by increasing the powder-to-liquid ratio. Incorporation of Sr-HA into CPC increased MTT assay (biocompatibility) and ALP activity (P<0.05). Histomorphometry showed greater bone formation after 4weeks, after implantation of Sr-HA/CPC in 10 rats compared to implantations of CPC or empty defects in the same rats (n=30, ANOVA P<0.05). METHODS AND RESULTS PERTAINING TO SIM-LOADED PLGA MICROSPHERES+NANOSTRONTIUM-CPC COMPOSITE: After SEM assessment, the produced composite of microspheres and enhanced CPC were implanted for 8weeks in 10 rabbits, along with positive and negative controls, enhanced CPC, and enhanced CPC plus SIM (n=50). In the control group, only a small amount of bone had been regenerated (localized at the boundary of the defect); whereas, other groups showed new bone formation within and around the materials. A significant difference was found in the osteogenesis induced by the groups sham control (16.96±1.01), bone materials (32.28±4.03), nanostrontium-CPC (24.84±2.6), nanostrontium-CPC-simvastatin (40.12±3.29), and SIM-loaded PLGA+nanostrontium-CPC (44.8±6.45) (ANOVA P

  11. Cement og politik

    DEFF Research Database (Denmark)

    Lund, Joachim

    2012-01-01

    as well as in the public sphere. Most of the extensive job creating measures he carried out as a minister for public works necessarily involved the use of great amounts of cement – the primary produce of F.L. Smidth & Co. Gunnar Larsen thus became an easy target for Communist propaganda, picturing him...... of the Soviet Union (including an F.L. Smidth & Co. cement plant in former Estonia). He spent the last 15 months of the occupation in Sweden and was arrested after having returned to Copenhagen in May, 1945. Although a Copenhagen city court prison sentence for economic collaboration was reversed, he had...

  12. Technology Roadmaps: Cement

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-07-01

    To support its roadmap work focusing on key technologies for emissions reductions, the International Energy Agency (IEA) also investigated one particular industry: cement. Cement production includes technologies that are both specific to this industry and those that are shared with other industries (e.g., grinding, fuel preparation, combustion, crushing, transport). An industry specific roadmap provides an effective mechanism to bring together several technology options. It outlines the potential for technological advancement for emissions reductions in one industry, as well as potential cross-industry collaboration.

  13. Cement Mason's Curriculum. Instructional Units.

    Science.gov (United States)

    Hendirx, Laborn J.; Patton, Bob

    To assist cement mason instructors in providing comprehensive instruction to their students, this curriculum guide treats both the skills and information necessary for cement masons in commercial and industrial construction. Ten sections are included, as follow: related information, covering orientation, safety, the history of cement, and applying…

  14. Reducing cement's CO2 footprint

    Science.gov (United States)

    van Oss, Hendrik G.

    2011-01-01

    The manufacturing process for Portland cement causes high levels of greenhouse gas emissions. However, environmental impacts can be reduced by using more energy-efficient kilns and replacing fossil energy with alternative fuels. Although carbon capture and new cements with less CO2 emission are still in the experimental phase, all these innovations can help develop a cleaner cement industry.

  15. Cementing a wellbore using cementing material encapsulated in a shell

    Energy Technology Data Exchange (ETDEWEB)

    Aines, Roger D.; Bourcier, William L.; Duoss, Eric B.; Floyd, III, William C.; Spadaccini, Christopher M.; Vericella, John J.; Cowan, Kenneth Michael

    2017-03-14

    A system for cementing a wellbore penetrating an earth formation into which a pipe extends. A cement material is positioned in the space between the wellbore and the pipe by circulated capsules containing the cement material through the pipe into the space between the wellbore and the pipe. The capsules contain the cementing material encapsulated in a shell. The capsules are added to a fluid and the fluid with capsules is circulated through the pipe into the space between the wellbore and the pipe. The shell is breached once the capsules contain the cementing material are in position in the space between the wellbore and the pipe.

  16. The mechanical effect of the existing cement mantle on the in-cement femoral revision.

    LENUS (Irish Health Repository)

    Keeling, Parnell

    2012-08-01

    Cement-in-cement revision hip arthroplasty is an increasingly popular technique to replace a loose femoral stem which retains much of the original cement mantle. However, some concern exists regarding the retention of the existing fatigued and aged cement in such cement-in-cement revisions. This study investigates whether leaving an existing fatigued and aged cement mantle degrades the mechanical performance of a cement-in-cement revision construct.

  17. Physical evaluation of a new pulp capping material developed from portland cement

    OpenAIRE

    Negm, Ahmed; Hassanien, Ehab; Abu-Seida, Ashraf; Nagy, Mohamed

    2016-01-01

    Background This study examined the effects of addition of 10% and 25% by weight calcium hydroxide on the physicochemical properties of Portland cement associated with 20% bismuth oxide in order to develop a new pulp capping material. Material and Methods The solubility, pH value, setting time, compressive strength, and push out bond strength of modified Portland were evaluated and compared to those of mineral trioxide aggregate (MTA) and Portland cement containing 20% bismuth oxide. Results T...

  18. Investigation on the potential of waste cooking oil as a grinding aid in Portland cement.

    Science.gov (United States)

    Li, Haoxin; Zhao, Jianfeng; Huang, Yuyan; Jiang, Zhengwu; Yang, Xiaojie; Yang, Zhenghong; Chen, Qing

    2016-12-15

    Although there are several methods for managing waste cooking oil (WCO), a significant result has not been achieved in China. A new method is required for safe WCO management that minimizes the environmental threat. In this context, this work was developed in which cement clinker and gypsum were interground with various WCOs, and their properties, such as grindability, water-cement ratio required to achieve a normal consistency, setting times, compressive strength, contents of calcium hydroxide and ettringite in the hardened paste, microstructure and economic and environmental considerations, were addressed in detail. The results show that, overall, WCO favorably improves cement grinding. WCO prolonged the cement setting times and resulted in longer setting times. Additionally, more remarkable effects were found in cements in which WCO contained more unsaturated fatty acid. WCOs increased the cement strength. However, this enhancement was rated with respect to the WCO contents and components. WCOs decreased the CH and AFt contents in the cement hardened paste. Even the AFt content at later ages was reduced when WCO was used. WCO also densify microstructure of the hardened cement paste. It is economically and environmentally feasible to use WCOs as grinding aids in the cement grinding process. These results contribute to the application of WCOs as grinding aids and to the safe management of WCO. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Shear Bond Strength of a Self-adhering Flowable Composite and a Flowable Base Composite to Mineral Trioxide Aggregate, Calcium-enriched Mixture Cement, and Biodentine.

    Science.gov (United States)

    Altunsoy, Mustafa; Tanrıver, Mehmet; Ok, Evren; Kucukyilmaz, Ebru

    2015-10-01

    The purpose of this study was to investigate the shear bond strength (SBS) of a self-adhering flowable composite (Vertise Flow; Kerr, Orange, CA) and a flowable composite (X-tra base; Voco GmbH, Cuxhaven, Germany) to mineral trioxide aggregate (MTA), Biodentine (Septodent, Saint-Maur-des-Fosses Cedex, France), and calcium-enriched mixture (CEM; Yektazist Dandan, Tehran, Iran). Sixty cylindric acrylic blocks with a hole (3 mm in diameter and 1.5 mm in height) were prepared. The acrylic blocks were filled with MTA, Biodentine, and CEM (n = 20) and accordingly allocated into 3 groups. The specimens were stored for 72 hours at 37°C and 100% humidity. Then, each group was divided into 2 subgroups according to the composite resin type used (n = 10). Vertise Flow and X-tra base were applied over MTA, Biodentine, and CEM and then polymerized. SBS was tested in a universal testing machine with a crosshead speed of 1 mm/min. Data were analyzed using 2-way analysis of variance and the Tukey test. The Vertise Flow-CEM and X-tra base-MTA groups showed significantly higher SBS values than the group made of Vertise flow-Biodentine (P  .05). MTA and CEM exhibited higher SBS than Biodentine; therefore, they could be preferred under flowable composites. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  20. Glass ionomer cements: effect of strontium substitution on esthetics, radiopacity and fluoride release.

    Science.gov (United States)

    Shahid, S; Hassan, U; Billington, R W; Hill, R G; Anderson, P

    2014-03-01

    SrO and SrF2 are widely used to replace CaO and CaF2 in ionomer glasses to produce radiopaque glass ionomer cements (GIC). The purpose of this study was to evaluate the effects of this substitution on release of ions from GIC as well as its effect on esthetics (translucency) and radiopacity. Cements were produced from ionomer glasses with varying content of Sr, Ca and F. The cements were stored in dilute acetic acid (pH 4.0) for up to 7 days at 37°C. Thereafter, the cements were removed and the solution was tested for F(-), Sr(2+), Ca(2+), and Al(3+) release. Radiopacity and translucency were measured according to BS EN ISO 9917-1:2003. Ion release was linear to t(1/2) suggesting that this is a diffusion controlled mechanism rather than dissolution. The fluoride release from the cements is enhanced where some or all calcium is replaced by strontium. Radiopacity shows a strong linear correlation with Sr content. All cements were more opaque than the C0.70 0.55 standard but less opaque than the C0.70 0.90 standard which is the limit for the ISO requirement for acceptance. This study shows that the replacement of calcium by strontium in a glass ionomer glass produces the expected increase in radiopacity of the cement without adverse effects on visual properties of the cement. The fluoride release from the cements is enhanced where some or all calcium is replaced by strontium. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  1. Mechanical properties of cement concrete composites containing nano-metakaolin

    Science.gov (United States)

    Supit, Steve Wilben Macquarie; Rumbayan, Rilya; Ticoalu, Adriana

    2017-11-01

    The use of nano materials in building construction has been recognized because of its high specific surface area, very small particle sizes and more amorphous nature of particles. These characteristics lead to increase the mechanical properties and durability of cement concrete composites. Metakaolin is one of the supplementary cementitious materials that has been used to replace cement in concrete. Therefore, it is interesting to investigate the effectiveness of metakaolin (in nano scale) in improving the mechanical properties including compressive strength, tensile strength and flexural strength of cement concretes. In this experiment, metakaolin was pulverized by using High Energy Milling before adding to the concrete mixes. The pozzolan Portland cement was replaced with 5% and 10% nano-metakaolin (by wt.). The result shows that the optimum amount of nano-metakaolin in cement concrete mixes is 10% (by wt.). The improvement in compressive strength is approximately 123% at 3 days, 85% at 7 days and 53% at 28 days, respectively. The tensile and flexural strength results also showed the influence of adding 10% nano-metakaolin (NK-10) in improving the properties of cement concrete (NK-0). Furthermore, the Backscattered Electron images and X-Ray Diffraction analysis were evaluated to support the above findings. The results analysis confirm the pores modification due to nano-metakaolin addition, the consumption of calcium hydroxide (CH) and the formation of Calcium Silicate Hydrate (CSH) gel as one of the beneficial effects of amorphous nano-metakaolin in improving the mechanical properties and densification of microstructure of mortar and concrete.

  2. Magnesium oxychloride cement concrete

    Indian Academy of Sciences (India)

    TECS

    ting. It is used in industrial floorings, ship decks, railway passenger coach floorings, hospital floors, ammunition factory floors, missile silos and underground armament factories and bunkers. Recently, concrete of high compres- sive and tensile strength prepared with magnesium oxy- chloride cement and recycled rubber ...

  3. Investigation of Pozzolanic Reaction in Nanosilica-Cement Blended Pastes Based on Solid-State Kinetic Models and 29Si MAS NMR

    Science.gov (United States)

    Moon, Jiho; Reda Taha, Mahmoud M.; Youm, Kwang-Soo; Kim, Jung J.

    2016-01-01

    The incorporation of pozzolanic materials in concrete has many beneficial effects to enhance the mechanical properties of concrete. The calcium silicate hydrates in cement matrix of concrete increase by pozzolanic reaction of silicates and calcium hydroxide. The fine pozzolanic particles fill spaces between clinker grains, thereby resulting in a denser cement matrix and interfacial transition zone between cement matrix and aggregates; this lowers the permeability and increases the compressive strength of concrete. In this study, Ordinary Portland Cement (OPC) was mixed with 1% and 3% nanosilica by weight to produce cement pastes with water to binder ratio (w/b) of 0.45. The specimens were cured for 7 days. 29Si nuclear magnetic resonance (NMR) experiments are conducted and conversion fraction of nanosilica is extracted. The results are compared with a solid-state kinetic model. It seems that pozzolanic reaction of nanosilica depends on the concentration of calcium hydroxide. PMID:28787904

  4. Investigation of Pozzolanic Reaction in Nanosilica-Cement Blended Pastes Based on Solid-State Kinetic Models and 29Si MAS NMR.

    Science.gov (United States)

    Moon, Jiho; Taha, Mahmoud M Reda; Youm, Kwang-Soo; Kim, Jung J

    2016-02-06

    The incorporation of pozzolanic materials in concrete has many beneficial effects to enhance the mechanical properties of concrete. The calcium silicate hydrates in cement matrix of concrete increase by pozzolanic reaction of silicates and calcium hydroxide. The fine pozzolanic particles fill spaces between clinker grains, thereby resulting in a denser cement matrix and interfacial transition zone between cement matrix and aggregates; this lowers the permeability and increases the compressive strength of concrete. In this study, Ordinary Portland Cement (OPC) was mixed with 1% and 3% nanosilica by weight to produce cement pastes with water to binder ratio (w/b) of 0.45. The specimens were cured for 7 days. 29Si nuclear magnetic resonance (NMR) experiments are conducted and conversion fraction of nanosilica is extracted. The results are compared with a solid-state kinetic model. It seems that pozzolanic reaction of nanosilica depends on the concentration of calcium hydroxide.

  5. Investigation of Pozzolanic Reaction in Nanosilica-Cement Blended Pastes Based on Solid-State Kinetic Models and 29Si MAS NMR

    Directory of Open Access Journals (Sweden)

    Jiho Moon

    2016-02-01

    Full Text Available The incorporation of pozzolanic materials in concrete has many beneficial effects to enhance the mechanical properties of concrete. The calcium silicate hydrates in cement matrix of concrete increase by pozzolanic reaction of silicates and calcium hydroxide. The fine pozzolanic particles fill spaces between clinker grains, thereby resulting in a denser cement matrix and interfacial transition zone between cement matrix and aggregates; this lowers the permeability and increases the compressive strength of concrete. In this study, Ordinary Portland Cement (OPC was mixed with 1% and 3% nanosilica by weight to produce cement pastes with water to binder ratio (w/b of 0.45. The specimens were cured for 7 days. 29Si nuclear magnetic resonance (NMR experiments are conducted and conversion fraction of nanosilica is extracted. The results are compared with a solid-state kinetic model. It seems that pozzolanic reaction of nanosilica depends on the concentration of calcium hydroxide.

  6. Processo de hidratação e os mecanismos de atuação dos aditivos aceleradores e retardadores de pega do cimento de aluminato de cálcio Hidration process and the mechanisms of retarding and accelerating the setting time of calcium aluminate cement

    Directory of Open Access Journals (Sweden)

    J. R. Garcia

    2007-03-01

    Full Text Available Um dos aspectos principais para o desenvolvimento de concretos refratários está no aprimoramento dos conhecimentos sobre o cimento de alta alumina ou cimento de aluminato de cálcio (CAC, já que esse ligante é o mais utilizado nesta classe de produtos. O objetivo desse trabalho foi o de analisar as informações disponíveis na literatura para se obter um conhecimento mais aprofundado dos mecanismos de ação dos aditivos retardadores e aceleradores da pega deste cimento. Da análise dos dados compilados pode-se concluir que os aditivos retardadores agem geralmente de duas maneiras: 1 dificultando o processo de dissolução do cimento, por meio da formação de barreiras insolúveis ao redor das suas partículas e 2 favorecendo a formação de hidratos mais solúveis, o que aumenta o tempo necessário para que se inicie a precipitação. Por outro lado, os aditivos aceleradores de pega podem atuar favorecendo a formação de hidratos menos solúveis, diminuindo assim o tempo necessário para a precipitação ou ainda pela formação de núcleos iniciadores do processo de crescimento dos cristais dos hidratos. A análise destas informações leva a constatação de que a ação de alguns aditivos retardadores e aceleradores ocorre em estágios distintos no processo de hidratação do CAC. Portanto, pode-se imaginar uma situação onde a combinação desses dois aditivos poderia conferir um tempo de trabalhabilidade adequado e seguro, aliado a um curto tempo de desmoldagem.One of the main aspects for the development of refractories castables is to master the knowledge regarding calcium aluminate cement (CAC, as this binder is the most applied in these products. The objective of this work was to analyze the available information in the literature in order to explain the understanding regarding the actions of retarder and accelerator additives in the setting mechanisms of CACs. The analysis of the compiled information pointed out that the

  7. Pulpal response of dogs primary teeth to an adhesive system or to a calcium hydroxide cement Resposta pulpar de dentes decíduos de cães a um sistema adesivo ou ao cimento de hidróxido de cálcio

    Directory of Open Access Journals (Sweden)

    Rosângela Almeida RIBEIRO

    2000-03-01

    Full Text Available The aim of this study was to evaluate the pulpal response of dogs primary teeth to an adhesive system or to a calcium hidroxide cement after mechanic exposure of the pulp. Three mongrel dogs were used and ten class V cavities were prepared on their teeth. A mechanic pulp exposure was produced with a sterile exploratory probe in the central portion of each cavity and bleeding was controlled with dry sterile cotton pellets. Enamel, dentin and the site of the pulp exposure of five teeth were etched with 35% phosphoric acid followed by the application of an adhesive system (Scotchbond Multi-Purpose - 3M. In the other five teeth, calcium hydroxide cement (Hydro C - Dentsply was applied on the site of the pulp exposition before application of the adhesive system (Scotchbond Multi-Purpose - 3M. All teeth were restored with a resin composite (Z-100 - 3M. After 7, 30 or 45 days the dogs were anesthetized and perfused with saline followed by a solution of neutral buffered formalin. Maxilla and mandible were sectioned into three parts and placed in a solution for demineralization. Following bone demineralization, all teeth were cut, trimmed, embedded in paraffin and longitudinally cut. Then, the teeth were stained with hematoxilin and eosin and observed under a light microscope. The results obtained with the treatments proposed in this study showed the presence and persistence of an inflammatory response of different intensities at the three experimental periods. There was no variation in the inflammatory response regarding the different treatments performed.O objetivo deste estudo foi de avaliar a resposta pulpar de dentes decíduos de cães à um sistema adesivo ou a um cimento de hidróxido de cálcio após exposição mecânica da polpa. Foram utilizados três cães sem raça definida, e nestes foram realizados dez preparos cavitários classe V. Uma exposição pulpar mecânica foi produzida com uma sonda exploradora esterilizada, na porção central

  8. Is your cement sheath stressed?

    Energy Technology Data Exchange (ETDEWEB)

    DeBruijn, G. [Schlumberger Well Cementing Services Canada, Calgary, AB (Canada)

    2007-07-01

    Wells are cemented for several reasons, most notably to provide zonal isolation; support the casing's axial load; maintain wellbore integrity; protect groundwater; and protect the casing from corrosion. This presentation addressed some of the concerns regarding the development of tensile cracks when drilling in high temperature high pressure wells during steam stimulation. Flexible cement solutions were also provided along with their key technical specifications. Simulations of cement sheath stress have shown that a cement system can operate in a dynamic stress environment if an optimized blend is used. Cement stress simulation enables the evaluation of zonal isolation risks. The paper indicated that of the 6 steam assisted gravity drainage (SAGD) wells in Canada that have used a flexible and expandable cement solution system developed by Schlumberger Well Cementing Services, none have shown signs of casing gas vent flow at surface. figs.

  9. Reinforcement Strategies for Load-Bearing Calcium Phosphate Biocements

    Directory of Open Access Journals (Sweden)

    Martha Geffers

    2015-05-01

    Full Text Available Calcium phosphate biocements based on calcium phosphate chemistry are well-established biomaterials for the repair of non-load bearing bone defects due to the brittle nature and low flexural strength of such cements. This article features reinforcement strategies of biocements based on various intrinsic or extrinsic material modifications to improve their strength and toughness. Altering particle size distribution in conjunction with using liquefiers reduces the amount of cement liquid necessary for cement paste preparation. This in turn decreases cement porosity and increases the mechanical performance, but does not change the brittle nature of the cements. The use of fibers may lead to a reinforcement of the matrix with a toughness increase of up to two orders of magnitude, but restricts at the same time cement injection for minimal invasive application techniques. A novel promising approach is the concept of dual-setting cements, in which a second hydrogel phase is simultaneously formed during setting, leading to more ductile cement–hydrogel composites with largely unaffected application properties.

  10. Microleakage of orthodontic band cement at the cement-enamel and cement-band interfaces.

    Science.gov (United States)

    Uysal, Tancan; Ramoglu, Sabri Ilhan; Ertas, Huseyin; Ulker, Mustafa

    2010-04-01

    Our objective was to determine and compare microleakage patterns of conventional glass ionomer cement (GIC), resin modified GIC (RMGIC), and polyacid-modified composite for band cementation. Sixty freshly extracted third molars were randomly divided into 3 groups of 20 teeth each. Microetched molar bands in the 3 groups were cemented to enamel with one of three orthodontic cements: Ketac-Cem (3M ESPE, Gmbh, Seefeld, Germany), Multi-Cure (3M Unitek, Monrovia, Calif), and Transbond Plus (3M Unitek). A dye penetration method was used for microleakage evaluation. Microleakage was determined by a stereomicroscope for the cement-band and cement-enamel interfaces from both the buccal and lingual margins. Statistical analysis was performed with Kruskal-Wallis and Mann-Whitney U tests. The buccal sides had similar microleakage values compared with the lingual sides for the cement-enamel and cement-band interfaces with all cements. Statistical comparisons showed statistically significant differences among the band cements between both interfaces (P <0.001). When the cement systems were compared, conventional GIC showed the highest leakage scores between cement-band (median, 3.50 mm) and cement-enamel (median, 2.88 mm) interfaces. Teeth banded with RMGIC and modified composite showed similar microleakage scores, and both had less leakage (<1 mm) than conventional GIC. Conventional GIC is associated with more microleakage than RMGIC and modified composite at both the cement-band and cement-enamel interfaces. Copyright (c) 2010 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  11. In Vitro Fit and Cementation Resistance of Provisional Crowns for Single Implant-Supported Restorations.

    Science.gov (United States)

    Moris, Izabela Cristina Maurício; Oliveira, Juliana Elias de; Faria, Adriana Cláudia Lapria; Ribeiro, Ricardo Faria; Rodrigues, Renata Cristina Silveira

    2015-10-01

    This study aimed to verify marginal fit and the effect of cement film thickness standardization on retention of provisional crowns made with prefabricated acrylic cylinders on abutments, using two temporary luting agents subjected or not to mechanical cycling. Provisional crowns were made from bis-acryl (Luxatemp Fluorescence) or methyl methacrylate (Duralay) resins on acrylic cylinders and marginal fit and cement film thickness were evaluated. For retention evaluation, crowns were cemented with two temporary luting agents: non-eugenol zinc oxide (Tempbond NE) or calcium hydroxide-based (Hydcal) cements and subjected to tensile strength in a universal testing machine. After cleaning, debonded crowns were cemented again, subjected to mechanical cycling and retention was reassessed. The results of marginal fit and cement film thickness were analyzed by Student's t-test while retention of cements before and after mechanical cycling was analyzed using a mixed linear model. Methyl methacrylate crowns presented greater marginal misfit (p=0.001) and occlusal cement film thickness (p=0.003) than the bis-acryl ones. No difference was observed at axial cement film thickness (p=0.606). Resins (p=0.281) did not affect crown retention, but luting agents (p=0.029) and mechanical cycling (p=0.027) showed significant effects. The only significant interaction was mechanical cycling*luting agents, which means that luting agents were differently affected by mechanical cycling (p=0.002). In conclusion, the results showed that bis-acryl resin associated to calcium-hydroxide luting agent provided the best retention and lower cement thickness.

  12. Suitability of alumina cements for the cementation of boreholes under corrosive conditions, especially at the press fitting of CO{sub 2}; Eignung von Tonerdezementen fuer die Bohrlochzementierung unter korrosiven Bedingungen, insbesondere bei CO{sub 2}-Einpressung. Literaturstudie

    Energy Technology Data Exchange (ETDEWEB)

    Plank, J.; Sieber, R. (comps.) [Technische Univ. Muenchen (Germany). Lehrstuhl fuer Bauchemie

    2011-07-15

    Calcium aluminate cements, also called aluminate cements, are special cements based on calcium aluminates. In construction (especially in dry-mix mortars), they are valued for their remarkably higher acid and corrosion resistance compared to Portland cement. Their high temperature resistance especially qualifies them for refractory cements which are used e.g. as liners in cement rotary kilns. The worldwide production of calcium aluminate cements adds up to about 3 million tons. In oil well cementing, calcium aluminate cements have first been used at the beginning of the 90ies, in fact initially for geothermal wells. Applications in permafrost soils as well as fire-flooding wells came later. The reason for the use in geothermal wells. Applications in permafrost soils as well as fire-flooding wells came later. The reason for the use in geothermal wells were severe problems with API Portland cements affected by hot, carbonic acid rich formation brines. With support from the companies Unocal and Halliburton, the Brookhaven National Laboratory (USA) developed a special cement based on 60 parts by weight of calcium aluminate cement and 40 parts ASTM class F fly ash. This binder is notably CO{sub 2} resistant when mixed with a 25 wt.% Na-polyphosphate solution. Laboratory tests and field applications conclude that this cement is resistant to CO{sub 2} corrosion at temperatures up to 300 C for over 20 years. In 1997, for the first time numerous geothermal wells have been cemented using this cement. They are intact to this day. When this cement hardens at room temperature, amorphous reaction products are formed and the reaction is incomplete. However, at higher temperatures hydroxyapatite, boehmite, Na-P-zeolite, analcime or katoite are formed as crystalline reaction products. The CO{sub 2} resistance of this cement is due to specific chemical reactions. In contact with hot alkaline carbonate solutions, analcime converts to cancrinite, and CO{sub 2} is incorporated into

  13. The effect of cement creep and cement fatigue damage on the micromechanics of the cement-bone interface.

    NARCIS (Netherlands)

    Waanders, D.; Janssen, D.; Mann, K.A.; Verdonschot, N.J.J.

    2010-01-01

    The cement-bone interface provides fixation for the cement mantle within the bone. The cement-bone interface is affected by fatigue loading in terms of fatigue damage or microcracks and creep, both mostly in the cement. This study investigates how fatigue damage and cement creep separately affect

  14. NMR study of hydrated calcium silicates; Etude par RMN de la structure des silicates de calcium hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Klur, I

    1996-02-26

    Radioactive wastes storage methods are developed by the CEA. As cements are important materials as well for hours living radioisotopes than for years living radioisotopes, a better knowledge of this material will allow to anticipate its behaviour and to obtain safer storage methods. The structure of calcium silicates (C-S-H) (main constituent of cements) have then been determined in this thesis by nuclear magnetic resonance. This method has allow to explain in structural terms, the different calcium rates that can be measured in the C-S-H too. (O.M.) 101 refs.

  15. Modified tricalcium silicate cement formulations with added zirconium oxide.

    Science.gov (United States)

    Li, Xin; Yoshihara, Kumiko; De Munck, Jan; Cokic, Stevan; Pongprueksa, Pong; Putzeys, Eveline; Pedano, Mariano; Chen, Zhi; Van Landuyt, Kirsten; Van Meerbeek, Bart

    2017-04-01

    This study aims to investigate the effect of modifying tricalcium silicate (TCS) cements on three key properties by adding ZrO 2 . TCS powders were prepared by adding ZrO 2 at six different concentrations. The powders were mixed with 1 M CaCl 2 solution at a 3:1 weight ratio. Biodentine (contains 5 wt.% ZrO 2 ) served as control. To evaluate the potential effect on mechanical properties, the mini-fracture toughness (mini-FT) was measured. Regarding bioactivity, Ca release was assessed using ICP-AES. The component distribution within the cement matrix was evaluated by Feg-SEM/EPMA. Cytotoxicity was assessed using an XTT assay. Adding ZrO 2 to TCS did not alter the mini-FT (p = 0.52), which remained in range of that of Biodentine (p = 0.31). Ca release from TSC cements was slightly lower than that from Biodentine at 1 day (p > 0.05). After 1 week, Ca release from TCS 30 and TCS 50 increased to a level that was significantly higher than that from Biodentine (p  0.05). EPMA revealed a more even distribution of ZrO 2 within the TCS cements. Particles with an un-reacted core were surrounded by a hydration zone. The 24-, 48-, and 72-h extracts of TCS 50 were the least cytotoxic. ZrO 2 can be added to TCS without affecting the mini-FT; Ca release was reduced initially, to reach a prolonged release thereafter; adding ZrO 2 made TCS cements more biocompatible. TCS 50 is a promising cement formulation to serve as a biocompatible hydraulic calcium silicate cement.

  16. Mineral resource of the month: hydraulic cement

    Science.gov (United States)

    van Oss, Hendrik G.

    2012-01-01

    Hydraulic cements are the binders in concrete and most mortars and stuccos. Concrete, particularly the reinforced variety, is the most versatile of all construction materials, and most of the hydraulic cement produced worldwide is portland cement or similar cements that have portland cement as a basis, such as blended cements and masonry cements. Cement typically makes up less than 15 percent of the concrete mix; most of the rest is aggregates. Not counting the weight of reinforcing media, 1 ton of cement will typically yield about 8 tons of concrete.

  17. Calcium Electroporation

    DEFF Research Database (Denmark)

    Frandsen, Stine Krog; Gibot, Laure; Madi, Moinecha

    2015-01-01

    BACKGROUND: Calcium electroporation describes the use of high voltage electric pulses to introduce supraphysiological calcium concentrations into cells. This promising method is currently in clinical trial as an anti-cancer treatment. One very important issue is the relation between tumor cell kill...... efficacy-and normal cell sensitivity. METHODS: Using a 3D spheroid cell culture model we have tested the effect of calcium electroporation and electrochemotherapy using bleomycin on three different human cancer cell lines: a colorectal adenocarcinoma (HT29), a bladder transitional cell carcinoma (SW780......), and a breast adenocarcinoma (MDA-MB231), as well as on primary normal human dermal fibroblasts (HDF-n). RESULTS: The results showed a clear reduction in spheroid size in all three cancer cell spheroids three days after treatment with respectively calcium electroporation (p

  18. INORGANIC CEMENT CONCRETE

    Directory of Open Access Journals (Sweden)

    Alisson Clay Rios Silva

    2014-07-01

    Full Text Available In this work, a Geopolymeric Cement Concrete (GCC was developed through adequate portions of geopolymer components. Its characteristics were compared with Portland Cement Concrete (PCC, through of the establishment of some parameters of design, as consumption of binders, water/aggregates ratio and mortar content. The concrete mechanical performance was evaluated with emphasis to the fatigue behavior. Were tested the effects of different tensile strength maximum (increasing and decreasing. The results of fatigue tests had shown that GCC presents a better performance when compared to PCC. Its fatigue strength was 15% higher than that of PCC, when 70% of rupture tension of the concrete in static bending (SR, was applied. Tensions of about 80% SR resulted in 96% of increase, when compared to GCC. The SEM microstructural analysis showed that the GCC has a matrix/aggregate bonding very strong, when compared to PCC, probably due to the massive nature of the geopolymeric matrix.

  19. US cement industry

    Energy Technology Data Exchange (ETDEWEB)

    Nisbet, M.A.

    1997-12-31

    This paper describes the cement and concrete industry, and provides data on energy use and carbon dioxide emissions. The potential impact of an energy tax on the industry is briefly assessed. Opportunities identified for reducing carbon dioxide emissions include improved energy efficiency, alternative fuels, and alternative materials. The key factor in determining CO{sub 2} emissions is the level of domestic production. The projected improvement in energy efficiency and the relatively slow growth in domestic shipments indicate that CO{sub 2} emissions in 2000 should be about 5% above the 1990 target. However, due to the cyclical nature of cement demand, emissions will probably be above target levels during peak demand and below target levels during demand troughs. 7 figs., 2 tabs.

  20. Development of novel tricalcium silicate-based endodontic cements with sintered radiopacifier phase.

    Science.gov (United States)

    Xuereb, M; Sorrentino, F; Damidot, D; Camilleri, Josette

    2016-06-01

    All implants, bone and endodontic cements need to be sufficiently radiopaque to be able to be distinguished from neighbouring anatomical structures post-operatively. For this purpose, radiopacifying materials are added to the cements to render them sufficiently radiopaque. Bismuth oxide has been quite a popular choice of radiopacifier in endodontic materials. It has been shown to cause dental discoloration. The aim of this study was to develop, characterize and assess the properties of tricalcium silicate cement with alternative radiopacifiers, which are either inter-ground or sintered to the tricalcium silicate cement. Custom-made endodontic cements based on tricalcium silicate and 20 % barium, calcium or strontium zirconate, which were either inter-ground or sintered at high temperatures, were produced. The set materials stored for 28 days in Hank's balanced salt solution were characterized by scanning electron microscopy and X-ray diffraction analysis. Assessment of pH, leaching, interaction with physiological solution, radiopacity, setting time, compressive strength and material porosity were investigated. Mineral trioxide aggregate (MTA) Angelus was used as control. Addition of radiopacifying materials improved the radiopacity of the material. The sintered cements exhibited the formation of calcium zirconate together with the respective radiopacifier phase. All materials produced calcium hydroxide on hydration, which interacted with tissue fluids forming hydroxyapatite on the material surface. The physical properties of the tricalcium silicate-based cements were comparable to MTA Angelus. A novel method of producing radiopaque tricalcium silicate-based cements was demonstrated. The novel materials exhibited properties, which were either comparable or else improved over the control. The novel materials can be used to replace MTA for root-end filling, perforation repair and other clinical applications where MTA is indicated.

  1. Traditional Portland cement and MgO-based cement: a promising combination?

    Science.gov (United States)

    Tonelli, Monica; Martini, Francesca; Calucci, Lucia; Geppi, Marco; Borsacchi, Silvia; Ridi, Francesca

    2017-06-01

    MgO/SiO2 cements are materials potentially very useful for radioactive waste disposal, but knowledge about their physico-chemical properties is still lacking. In this paper we investigated the hydration kinetics of cementitious formulations prepared by mixing MgO/SiO2 and Portland cement in different proportions and the structural properties of the hydrated phases formed in the first month of hydration. In particular, the hydration kinetics was investigated by measuring the free water index on pastes by means of differential scanning calorimetry, while the structural characterization was carried out by combining thermal (DTA), diffractometric (XRD), and spectroscopic (FTIR, 29Si solid state NMR) techniques. It was found that calcium silicate hydrate (C-S-H) and magnesium silicate hydrate (M-S-H) gels mainly form as separate phases, their relative amount and structural characteristics depending on the composition of the hydrated mixture. Moreover, the composition of the mixtures strongly affects the kinetics of hydration and the pH of the aqueous phase in contact with the cementitious materials. The results here reported show that suitable mixtures of Portland cement and MgO/SiO2 could be used to modify the properties of hydrated phases with potential application in the storage of nuclear waste in clayey disposal.

  2. Performance of Cement Containing Laterite as Supplementary Cementing Material

    Directory of Open Access Journals (Sweden)

    Abbas Bukhari, Z. S.

    2013-03-01

    Full Text Available The utilization of different industrial waste, by-products or other materials such as ground granulated blast furnace slag, silica fume, fly ash, limestone, and kiln dust, etc. as supplemen- tary cementing materials has received considerable attention in recent years. A study has been conducted to look into the performance of laterite as Supplementary Cementing Materials (SCM. The study focuses on compressive strength performance of blended cement containing different percentage of laterite. The cement is replaced accordingly with percentage of 2 %, 5 %, 7 % and 10 % by weight. In addition, the effect of use of three chemically different laterites have been studied on physical performance of cement as in setting time, Le-Chatlier expansion, loss on ignition, insoluble residue, free lime and specifically compressive strength of cement cubes tested at the age of 3, 7, and 28 days. The results show that the strength of cement blended with laterite as SCM is enhanced. Key words: Portland cement, supplementary cementing materials (SCM, laterite, compressive strength KUI – 6/2013 Received January 4, 2012 Accepted February 11, 2013

  3. Hydration characteristics of zirconium oxide replaced Portland cement for use as a root-end filling material.

    Science.gov (United States)

    Camilleri, J; Cutajar, A; Mallia, B

    2011-08-01

    Zirconium oxide can be added to dental materials rendering them sufficiently radiopaque. It can thus be used to replace the bismuth oxide in mineral trioxide aggregate (MTA). Replacement of Portland cement with 30% zirconium oxide mixed at a water/cement ratio of 0.3 resulted in a material with adequate physical properties. This study aimed at investigating the microstructure, pH and leaching in physiological solution of Portland cement replaced zirconium oxide at either water-powder or water-cement ratios of 0.3 for use as a root-end filling material. The hydration characteristics of the materials which exhibited optimal behavior were evaluated. Portland cement replaced by zirconium oxide in varying amounts ranging from 0 to 50% in increments of 10 was prepared and divided into two sets. One set was prepared at a constant water/cement ratio while the other set at a constant water/powder ratio of 0.3. Portland cement and MTA were used as controls. The materials were analyzed under the scanning electron microscope (SEM) and the hydration products were determined. X-ray energy dispersive analysis (EDX) was used to analyze the elemental composition of the hydration products. The pH and the amount of leachate in Hank's balanced salt solution (HBSS) were evaluated. A material that had optimal properties that satisfied set criteria and could replace MTA was selected. The microstructure of the prototype material and Portland cement used as a control was assessed after 30 days using SEM and atomic ratio diagrams of Al/Ca versus Si/Ca and S/Ca versus Al/Ca were plotted. The hydration products of Portland cement replaced with 30% zirconium oxide mixed at water/cement ratio of 0.3 were calcium silicate hydrate, calcium hydroxide and minimal amounts of ettringite and monosulphate. The calcium hydroxide leached in HBSS solution resulted in an increase in the pH value. The zirconium oxide acted as inert filler and exhibited no reaction with the hydration by-products of Portland

  4. Systemic effect of mineral aggregate-based cements: histopathological analysis in rats

    Directory of Open Access Journals (Sweden)

    Lucas da Fonseca Roberti Garcia

    Full Text Available Abstract Objective: Several studies reported the local tissue reaction caused by mineral aggregate-based cements. However, few studies have investigated the systemic effects promoted by these cements on liver and kidney when directly applied to connective tissue. The purpose of this in vivo study was to investigate the systemic effect of mineral aggregate-based cements on the livers and kidneys of rats. Material and Methods: Samples of Mineral Trioxide Aggregate (MTA and a calcium aluminate-based cement (EndoBinder containing different radiopacifiers were implanted into the dorsum of 40 rats. After 7 and 30 d, samples of subcutaneous, liver and kidney tissues were submitted to histopathological analysis. A score (0-3 was used to grade the inflammatory reaction. Blood samples were collected to evaluate changes in hepatic and renal functions of animals. Results: The moderate inflammatory reaction (2 observed for 7 d in the subcutaneous tissue decreased with time for all cements. The thickness of inflammatory capsules also presented a significant decrease with time (P<.05. Systemically, all cements caused adverse inflammatory reactions in the liver and kidney, being more evident for MTA, persisting until the end of the analysis. Liver functions increased significantly for MTA during 30 d (P<.05. Conclusion: The different cements induced to a locally limited inflammatory reaction. However, from the systemic point of view, the cements promoted significant inflammatory reactions in the liver and kidney. For MTA, the reactions were more accentuated.

  5. Center for Coal-Derived Low Energy Materials for Sustainable Construction

    Energy Technology Data Exchange (ETDEWEB)

    Jewell, Robert; Robl, Tom; Rathbone, Robert

    2012-06-30

    The overarching goal of this project was to create a sustained center to support the continued development of new products and industries that manufacture construction materials from coal combustion by-products or CCB’s (e.g., cements, grouts, wallboard, masonry block, fillers, roofing materials, etc). Specific objectives includes the development of a research kiln and associated system and the formulation and production of high performance low-energy, low-CO2 emitting calcium sulfoaluminate (CAS) cement that utilize coal combustion byproducts as raw materials.

  6. Physicochemical changes of cements by ground water corrosion in radioactive waste storage; Evolucion fisicoquimica de los cementos por corrosion de aguas subterraneas en un almacen de desechos radioactivos

    Energy Technology Data Exchange (ETDEWEB)

    Contreras R, A.; Badillo A, V. E.; Robles P, E. F. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Nava E, N. [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas No. 152, Col. San Bartolo Atepehuacan, 07730 Mexico D. F. (Mexico)], e-mail: aida.contreras@inin.gob.mx

    2009-10-15

    Knowing that the behavior of cementations materials based on known hydraulic cement binder is determined essentially by the physical and chemical transformation of cement paste (water + cement) that is, the present study is essentially about the cement paste evolution in contact with aqueous solutions since one of principal risks in systems security are the ground and surface waters, which contribute to alteration of various barriers and represent the main route of radionuclides transport. In this research, cements were hydrated with different relations cement-aqueous solution to different times. The pastes were analyzed by different solid observation techniques XRD and Moessbauer with the purpose of identify phases that form when are in contact with aqueous solutions of similar composition to ground water. The results show a definitive influence of chemical nature of aqueous solution as it encourages the formation of new phases like hydrated calcium silicates, which are the main phases responsible of radionuclides retention in a radioactive waste storage. (Author)

  7. [Haemotoxicity of dental luting cements].

    Science.gov (United States)

    Anders, A; Welker, D

    1989-06-01

    A glass ionomer luting cement (AquaCem) shows a relatively low haemolytic activity in comparison with two zinc phosphate cements. Especially the initial irritation by this cement is smaller. Although it is possible that AquaCem particularly, in unfavourable cases, may damage the pulpa dentin system; this is due to the slowly decrease of the haemolytic activity with increasing of the probes. We found that Adhesor showed in dependence of the batches a varying quality.

  8. Manufacture Of Pozzolanic Cement From RFCC Spent Catalyst In Khartoum Refinery

    Directory of Open Access Journals (Sweden)

    Husam E Mustafa

    2015-08-01

    Full Text Available Pozzolana is defined as Siliceous and aluminous material which reacts with calcium hydroxide in presence of water at room temperature to form strong slow-hardening cement. Pozzolana has the advantage of reduction of leachibility of calcium hydroxide liberated during the setting and hydration of cement. In Khartoum Refinery five to ten tons per week of spent catalyst are produced in fine powder this quantity is sent to dumping sites or landfills. In this study pilot experiments were successfully carried out at different ratios to produce cement. The RFCC spent catalyst samples were subjected to chemical analysis to determine the content of Al2O3 SiO3TiO3 CaO and V2O5 ..etc. These were found to be 49.5 41.1 0.32 1.4 and 0.09 percent respectively other compounds are Na2O MgO P2O5SO3 K2O MnOFe2O3Co3O4 and NiO2 with. It is found that the percentages of SiO2 Al2O3 and Fe2O3 amount up to 91.5 that is above the ASTM standard C6182003 which stipulated that the minimum of such compound is 70 . Physical properties of RFCC spent catalyst were also carried out including crystallinity and Pozzolanicity index. The cement produced was tested for compressive strength consistency and setting time .It is concluded that RFCC spent catalyst in Khartoum Refinery is a Pozzolanic material and up to 30 replacement from Portland cement blended cement complies with the Sudanese and European Standards No SSMO 39982011and EN-197-11992 respectively. The study shows that the compressive strength of blended Pozzolanic cements decreases with increasing Pozzolana content. From the foregoing it is recommended to use RFCC spent catalyst with Portland cement as blended cement to produce mortars for construction and concrete.

  9. Application of Bacillus subtilis 168 as a multifunctional agent for improvement of the durability of cement mortar.

    Science.gov (United States)

    Park, Sung-Jin; Park, Jong-Myong; Kim, Wha-Jung; Ghim, Sa-Youl

    2012-11-01

    Microbiological calcium carbonate precipitation (MCCP) has been investigated for its ability to improve the durability of cement mortar. However, very few strains have been applied to crack remediation and strengthening of cementitious materials. In this study, we report the biodeposition of Bacillus subtilis 168 and its ability to enhance the durability of cement material. B. subtilis 168 was applied to the surface of cement specimens. The results showed a new layer of deposited organic-inorganic composites on the surface of the cement paste. In addition, the water permeability of the cement paste treated with B. subtilis 168 was lower than that of non-treated specimens. Furthermore, artificial cracks in the cement paste were completely remediated by the biodeposition of B. subtilis 168. The compressive strength of cement mortar treated with B. subtilis 168 increased by about 19.5% when compared with samples completed with only B4 medium. Taken together, these findings suggest that the biodeposition of B. subtilis 168 could be used as a sealing and coating agent to improve the strength and water resistance of concrete. This is the first paper to report the application of Bacillus subtilis 168 for its ability to improve the durability of cement mortar through calcium carbonate precipitation.

  10. Hydration states of AFm cement phases

    Energy Technology Data Exchange (ETDEWEB)

    Baquerizo, Luis G., E-mail: luis.baquerizoibarra@holcim.com [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Matschei, Thomas [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Scrivener, Karen L. [Laboratory of Construction Materials, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Saeidpour, Mahsa; Wadsö, Lars [Building Materials, Lund University, Box 124, 221 000 Lund (Sweden)

    2015-07-15

    The AFm phase, one of the main products formed during the hydration of Portland and calcium aluminate cement based systems, belongs to the layered double hydrate (LDH) family having positively charged layers and water plus charge-balancing anions in the interlayer. It is known that these phases present different hydration states (i.e. varying water content) depending on the relative humidity (RH), temperature and anion type, which might be linked to volume changes (swelling and shrinkage). Unfortunately the stability conditions of these phases are insufficiently reported. This paper presents novel experimental results on the different hydration states of the most important AFm phases: monocarboaluminate, hemicarboaluminate, strätlingite, hydroxy-AFm and monosulfoaluminate, and the thermodynamic properties associated with changes in their water content during absorption/desorption. This data opens the possibility to model the response of cementitious systems during drying and wetting and to engineer systems more resistant to harsh external conditions.

  11. Développement d'une matrice à base d'aluminate de calcium pour la cimentation de boues issues de la décontamination d'effluents actifs

    OpenAIRE

    Martin, Isabelle

    2016-01-01

    Nuclear industry generated waste including radioactive wastes, which have different forms and origins. The wastes produced by reprocessing of nuclear fuel are characterized by important water content, by high pH and temperature sensitivity. The cementation in ettringite systems might be a promising solution to solidify radioactive wastes. Mixtures of Calcium Aluminate Cement (CAC) and calcium sulfate are planned to be used, instead of Ordinary Portland Cement (OPC), to form a significant amou...

  12. Thermal Shock-resistant Cement

    Energy Technology Data Exchange (ETDEWEB)

    Sugama T.; Pyatina, T.; Gill, S.

    2012-02-01

    We studied the effectiveness of sodium silicate-activated Class F fly ash in improving the thermal shock resistance and in extending the onset of hydration of Secar #80 refractory cement. When the dry mix cement, consisting of Secar #80, Class F fly ash, and sodium silicate, came in contact with water, NaOH derived from the dissolution of sodium silicate preferentially reacted with Class F fly ash, rather than the #80, to dissociate silicate anions from Class F fly ash. Then, these dissociated silicate ions delayed significantly the hydration of #80 possessing a rapid setting behavior. We undertook a multiple heating -water cooling quenching-cycle test to evaluate the cement’s resistance to thermal shock. In one cycle, we heated the 200 and #61616;C-autoclaved cement at 500 and #61616;C for 24 hours, and then the heated cement was rapidly immersed in water at 25 and #61616;C. This cycle was repeated five times. The phase composition of the autoclaved #80/Class F fly ash blend cements comprised four crystalline hydration products, boehmite, katoite, hydrogrossular, and hydroxysodalite, responsible for strengthening cement. After a test of 5-cycle heat-water quenching, we observed three crystalline phase-transformations in this autoclaved cement: boehmite and #61614; and #61543;-Al2O3, katoite and #61614; calcite, and hydroxysodalite and #61614; carbonated sodalite. Among those, the hydroxysodalite and #61614; carbonated sodalite transformation not only played a pivotal role in densifying the cementitious structure and in sustaining the original compressive strength developed after autoclaving, but also offered an improved resistance of the #80 cement to thermal shock. In contrast, autoclaved Class G well cement with and without Class F fly ash and quartz flour failed this cycle test, generating multiple cracks in the cement. The major reason for such impairment was the hydration of lime derived from the dehydroxylation of portlandite formed in the autoclaved

  13. Cements in the 21(st) Century: Challenges, Perspectives, and Opportunities.

    Science.gov (United States)

    Biernacki, Joseph J; Bullard, Jeffrey W; Sant, Gaurav; Banthia, Nemkumar; Brown, Kevin; Glasser, Fredrik P; Jones, Scott; Ley, Tyler; Livingston, Richard; Nicoleau, Luc; Olek, Jan; Sanchez, Florence; Shahsavari, Rouzbeh; Stutzman, Paul E; Sobolev, Konstantine; Prater, Tracie

    2017-07-01

    In a book published in 1906, Richard Meade outlined the history of portland cement up to that point(1). Since then there has been great progress in portland cement-based construction materials technologies brought about by advances in the materials science of composites and the development of chemical additives (admixtures) for applications. The resulting functionalities, together with its economy and the sheer abundance of its raw materials, have elevated ordinary portland cement (OPC) concrete to the status of most used synthetic material on Earth. While the 20(th) century was characterized by the emergence of computer technology, computational science and engineering, and instrumental analysis, the fundamental composition of portland cement has remained surprisingly constant. And, although our understanding of ordinary portland cement (OPC) chemistry has grown tremendously, the intermediate steps in hydration and the nature of calcium silicate hydrate (C-S-H), the major product of OPC hydration, remain clouded in uncertainty. Nonetheless, the century also witnessed great advances in the materials technology of cement despite the uncertain understanding of its most fundamental components. Unfortunately, OPC also has a tremendous consumption-based environmental impact, and concrete made from OPC has a poor strength-to-weight ratio. If these challenges are not addressed, the dominance of OPC could wane over the next 100 years. With this in mind, this paper envisions what the 21(st) century holds in store for OPC in terms of the driving forces that will shape our continued use of this material. Will a new material replace OPC, and concrete as we know it today, as the preeminent infrastructure construction material?

  14. Inorganic Corrosion-Inhibitive Pigments for High-Temperature Alkali-activated Well Casing Foam Cement

    Energy Technology Data Exchange (ETDEWEB)

    Sugama, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Pyatina, T. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2014-11-01

    This study evaluates inorganic pigments for improving carbon steel (CS) brine-corrosion protection by the sodium metasilicate-activated calcium aluminate cement/Fly Ash blend at 300°C. Calcium borosilicate (CBS) and zinc phosphate, significantly improved CS corrosion-protection by decreasing cement’s permeability for corrosive ions and inhibiting anodic corrosion. An amorphous Na2O-Al2O3-SiO2-H2O phase tightly attached to CS surface formed at 300oC in CBS-modified cement pore solution. The corrosion rate of the CS covered with this phase was nearly 4-fold lower than in the case of nonmodified cement pore solution where the major phase formed on the surface of CS was crystalline analcime.

  15. Inorganic Corrosion-Inhibitive Pigments for High-Temperature Alkali-activated Well Casing Foam Cement

    Energy Technology Data Exchange (ETDEWEB)

    Sugama, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Pyatina, T. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2014-11-14

    This study evaluates inorganic pigments for improving carbon steel (CS) brine-corrosion protection by the sodium metasilicate-activated calcium aluminate cement/Fly Ash blend at 300°C. Calcium borosilicate (CBS) and zinc phosphate, significantly improved CS corrosion-protection by decreasing cement’s permeability for corrosive ions and inhibiting anodic corrosion. An amorphous Na2O-Al2O3-SiO2-H2O phase tightly attached to CS surface formed at 300oC in CBS-modified cement pore solution. The corrosion rate of the CS covered with this phase was nearly 4-fold lower than in the case of nonmodified cement pore solution where the major phase formed on the surface of CS was crystalline analcime.

  16. [Thermal diffusivity of dental cements].

    Science.gov (United States)

    Paroussis, D; Kakaboura, A; Chrysafidis, C; Mauroyiannakis, E

    1990-08-01

    Thermal insulative efficiency, is one of the desirable properties of the dental cements. In this study, the thermal diffusivity of three types of dental cements, were measured. Thermal diffusivity was determined by the following method. Two thermo-couples were used and connected to a chart record, the first was embedded in the cylindrical block of the cement specimen and the other in a mixing of ice and water (reference thermocouple). All them were set in a apparatus consisting of a double cooling bath. Calculation of thermal diffusivity were based on the curve provided of the record during cooling of the cement and a theoretical mathematic model. Values were ranged from 2,985 to 3,934 cm2.sec-1. ZOE cement exhibited the highest value, the glass-ionomers the lowest and the poly-carboxylates were average. The results showed that the thermal diffusivity of the cements is dependent from the type of the cement but the differences between them were not statistically significant. Additionally, the values obtained were about the same as the dentin, so the dental cements may consider as good thermal insulators.

  17. Synchrotron Radiation Pair Distribution Function Analysis of Gels in Cements

    Directory of Open Access Journals (Sweden)

    Ana Cuesta

    2017-10-01

    Full Text Available The analysis of atomic ordering in a nanocrystalline phase with small particle sizes, below 5 nm, is intrinsically complicated because of the lack of long-range order. Furthermore, the presence of additional crystalline phase(s may exacerbate the problem, as is the case in cement pastes. Here, we use the synchrotron pair distribution function (PDF chiefly to characterize the local atomic order of the nanocrystalline phases, gels, in cement pastes. We have used a multi r-range analysis approach, where the ~4–7 nm r-range allows determining the crystalline phase contents; the ~1–2.5 nm r-range is used to characterize the atomic ordering in the nanocrystalline component; and the ~0.2–1.0 nm r-range gives insights about additional amorphous components. Specifically, we have prepared four alite pastes with variable water contents, and the analyses showed that a defective tobermorite, Ca11Si9O28(OH2.8.5H2O, gave the best fit. Furthermore, the PDF analyses suggest that the calcium silicate hydrate gel is composed of this tobermorite and amorphous calcium hydroxide. Finally, this approach has been used to study alternative cements. The hydration of monocalcium aluminate and ye’elimite pastes yield aluminum hydroxide gels. PDF analyses show that these gels are constituted of nanocrystalline gibbsite, and the particle size can be as small as 2.5 nm.

  18. A novel method to produce dry geopolymer cement powder

    Directory of Open Access Journals (Sweden)

    H.A. Abdel-Gawwad

    2016-04-01

    Full Text Available Geopolymer cement is the result of reaction of two materials containing aluminosilicate and concentrated alkaline solution to produce an inorganic polymer binder. The alkali solutions are corrosive and often viscous solutions which are not user friendly, and would be difficult to use for bulk production. This work aims to produce one-mix geopolymer mixed water that could be an alternative to Portland cement by blending with dry activator. Sodium hydroxide (SH was dissolved in water and added to calcium carbonate (CC then dried at 80 °C for 8 h followed by pulverization to a fixed particle size to produce the dry activator consisting of calcium hydroxide (CH, sodium carbonate (SC and pirssonite (P. This increases their commercial availability. The dry activator was blended with granulated blast-furnace slag (GBFS to produce geopolymer cement powder and by addition of water; the geopolymerization process is started. The effect of W/C and SH/CC ratio on the physico-mechanical properties of slag pastes was studied. The results showed that the optimum percent of activator and CC content is 4% SH and 5% CC, by the weight of slag, which give the highest physico-mechanical properties of GBFS. The characterization of the activated slag pastes was carried out using TGA, DTG, IR spectroscopy and SEM techniques.

  19. Get Enough Calcium

    Science.gov (United States)

    ... Calcium Print This Topic En español Get Enough Calcium Browse Sections The Basics Overview Foods and Vitamins ... women, don't get enough calcium. How much calcium do I need every day? Women: If you ...

  20. Calcium carbonate overdose

    Science.gov (United States)

    Tums overdose; Calcium overdose ... Calcium carbonate can be dangerous in large amounts. ... Some products that contain calcium carbonate are certain: ... and mineral supplements Other products may also contain calcium ...

  1. Ion release, fluoride charge of and adhesion of an orthodontic cement paste containing microcapsules.

    Science.gov (United States)

    Burbank, Brant D; Slater, Michael; Kava, Alyssa; Doyle, James; McHale, William A; Latta, Mark A; Gross, Stephen M

    2016-02-01

    Dental materials capable of releasing calcium, phosphate and fluoride are of great interest for remineralization. Microencapsulated aqueous solutions of these ions in orthodontic cement demonstrate slow, sustained release by passive diffusion through a permeable membrane without the need for dissolution or etching of fillers. The potential to charge a dental material formulated with microencapsulated water with fluoride by toothbrushing with over the counter toothpaste and the effect of microcapsules on cement adhesion to enamel was determined. Orthodontic cements that contained microcapsules with water and controls without microcapsules were brushed with over-the-counter toothpaste and fluoride release was measured. Adhesion measurements were performed loading orthodontic brackets to failure. Cements that contained microencapsulated solutions of 5.0M Ca(NO3)2, 0.8M NaF, 6.0MK2HPO4 or a mixture of all three were prepared. Ion release profiles were measured as a function of time. A greater fluoride charge and re-release from toothbrushing was demonstrated compared to a control with no microcapsules. Adhesion of an orthodontic cement that contained microencapsulated remineralizing agents was 8.5±2.5MPa compared to the control without microcapsules which was of 8.3±1.7MPa. Sustained release of fluoride, calcium and phosphate ions from cement formulated with microencapsulated remineralizing agents was demonstrated. Orthodontic cements with microcapsules show a release of bioavailable fluoride, calcium, and phosphate ions near the tooth surface while having the ability to charge with fluoride and not effect the adhesion of the material to enamel. Incorporation of microcapsules in dental materials is promising for promoting remineralization. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Determination of Diffusion Profiles in Altered Wellbore Cement Using X-ray Computed Tomography Methods

    Energy Technology Data Exchange (ETDEWEB)

    Mason, Harris E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Walsh, Stuart D. C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); DuFrane, Wyatt L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Carroll, Susan A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-06-17

    The development of accurate, predictive models for use in determining wellbore integrity requires detailed information about the chemical and mechanical changes occurring in hardened Portland cements. X-ray computed tomography (XRCT) provides a method that can nondestructively probe these changes in three dimensions. Here, we describe a method for extracting subvoxel mineralogical and chemical information from synchrotron XRCT images by combining advanced image segmentation with geochemical models of cement alteration. The method relies on determining “effective linear activity coefficients” (ELAC) for the white light source to generate calibration curves that relate the image grayscales to material composition. The resulting data set supports the modeling of cement alteration by CO2-rich brine with discrete increases in calcium concentration at reaction boundaries. The results of these XRCT analyses can be used to further improve coupled geochemical and mechanical models of cement alteration in the wellbore environment.

  3. Treatment of a Vertical Root Fracture Using Dual-Curing Resin Cement: A Case Report

    Directory of Open Access Journals (Sweden)

    Nima Moradi Majd

    2012-01-01

    Full Text Available Introduction. Vertical root fracture (VRF is one of the most frustrating complications of root canal treatment. The prognosis of the root with VRF is poor therefore tooth extraction and root amputation are usually the only treatment options. However, bonding of the fracture line with adhesive resin cement during the intentional replantation procedure was recently suggested as an alternative to tooth extraction. Methods. A vertically fractured left maxillary incisor was carefully extracted, fracture line was treated with adhesive resin cement, a retrograde cavity was produced and filled with calcium-enriched mixture (CEM cement, and tooth was replanted. Results. After 12 months the tooth was asymptomatic. The size of periapical radiolucency was noticeably reduced and there was no clinical sign of ankylosis. Conclusion. Using adhesive resin cement to bond the fracture lines extraorally in roots with VRF and intentional replantation of the reconstructed teeth could be considered as an alternative to tooth extraction, especially for anterior teeth.

  4. Thermogravimetric analysis of phase transitions in cement compositions mixed by sodium silicate solution

    Directory of Open Access Journals (Sweden)

    Fedosov Sergey Viktorovich

    2014-01-01

    Full Text Available This paper presents a study of the capability to modify cement by mechanical activation of sodium silicate water solution. Admixtures or blends of binding agents were employed for modifying concrete properties. The liquid glass is applied to protect from chemically or physically unfavorable environmental impacts, such as acidic medium and high temperature. The sodium silicate is a high-capacity setting accelerator. The increasing of the liquid glass proportion in the mix leads to the degradation of the cement paste plasticity and for this reason it is necessary to reduce the amount of liquid glass in the cement paste. The activation of dilute water solution of sodium silicate into rotary pulsating apparatus directly before tempering of the cement paste is an effective way to decrease mass fraction of liquid glass in the cement paste. The results of the combined influence of liquid glass and mechanical activation on physicochemical processes taking place in cement stone are represented in this research. Thermogravimetric analysis was used in order to study cement blends. Thermogravimetric analysis of modified cement stone assays was performed by thermo analyzer SETARAM TGA 92-24. The results of the analysis of phase transition taking place under high-temperature heating of cement stone modified by the mechanical activation of the water solution of the sodium silicate were introduced. Thermograms of cement stone assays were obtained at different hardening age. The comparison of these thermograms allows us to come to a conclusion on the formation and the retention during long time of a more dense structure of the composite matrix mixed by the mechanical activation of sodium silicate water solution. The relation between the concrete composition and its strength properties was stated. Perhaps, the capability of modified concrete to keep calcium ions in sparingly soluble hydrosilicates leads to the increase in its durability and corrosion resistance.

  5. Optimization of a biomimetic bone cement: role of DCPD.

    Science.gov (United States)

    Panzavolta, Silvia; Bracci, Barbara; Rubini, Katia; Bigi, Adriana

    2011-08-01

    We previously proposed a biomimetic α-tricalcium phosphate (α-TCP) bone cement where gelatin controls the transformation of α-TCP into calcium deficient hydroxyapatite (CDHA), leading to improved mechanical properties. In this study we investigated the setting and hardening processes of biomimetic cements containing increasing amounts of CaHPO(4)·2H2O (DCPD) (0, 2.5, 5, 10, 15 wt.%), with the aim to optimize composition. Both initial and final setting times increased significantly when DCPD content accounts for 10 wt.%, whereas cements containing 15 wt.% DCPD did not set at all. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), thermogravimetry (TG) and scanning electron microscopy (SEM) investigations were performed on samples maintained in physiological solution for different times. DCPD dissolution starts soon after cement preparation, but the rate of transformation decreases on increasing DCPD initial content in the samples. The rate of α-TCP to CDHA conversion during hardening decreases on increasing DCPD initial content. Moreover, the presence of DCPD prevents gelatin release during hardening. The combined effects of gelatin and DCPD on the rate of CDHA formation and porosity lead to significantly improved mechanical properties, with the best composition displaying a compressive strength of 35 MPa and a Young modulus of 1600 MPa. Copyright © 2011 Elsevier Inc. All rights reserved.

  6. A review of binders used in cemented paste tailings for underground and surface disposal practices.

    Science.gov (United States)

    Tariq, Amjad; Yanful, Ernest K

    2013-12-15

    Increased public awareness of environmental issues coupled with increasingly stringent environmental regulations pertaining to the disposal of sulphidic mine waste necessitates the mining industry to adopt more competent and efficient approaches to manage acid rock drainage. Cemented paste tailings (CPT) is an innovative form of amalgamated material currently available to the mining industry in developed countries. It is made usually from mill tailings mingled with a small amount of binder (customarily Portland cement) and water. The high cost associated with production and haulage of ordinary Portland cement and its alleged average performance as a sole binder in the long term (due to vulnerability to internal sulphate attack) have prompted users to appraise less expensive and technically efficient substitutes for mine tailings paste formulations. Generally, these binders include but are not limited to sulphate resistant cements, and/or as a partial replacement for Portland cement by artificial pozzolans, natural pozzolans, calcium sulphate substances and sodium silicates. The approach to designing environmentally efficient CPT is to ensure long-term stability and effective control over environmental contaminants through the use of composite binder systems with enhanced engineering properties to cater for inherit deficiencies in the individual constituents. The alkaline pore solution created by high free calcium rich cement kiln dust (CKD) (byproduct of cement manufacturing) is capable of disintegrating the solid glassy network of artificial pozzolans to produce reactive silicate and aluminate species when attacked by (OH(-)) ions. The augmented pozzolanic reactivity of CKD-slag and CKD-fly ash systems may produce resilient CPT. Since cemented paste comprising mine tailings and binders is a relatively new technology, a review of the binding materials used in such formulations and their performance evaluation in mechanical fill behaviour was considered pertinent in

  7. A soft matter in construction - Statistical physics approach to formation and mechanics of C-S-H gels in cement

    Science.gov (United States)

    Del Gado, E.; Ioannidou, K.; Masoero, E.; Baronnet, A.; Pellenq, R. J.-M.; Ulm, F.-J.; Yip, S.

    2014-10-01

    Calcium-silicate hydrate (C-S-H) is the main binding agent in cement and concrete. It forms at the beginning of cement hydration, it progressively densifies as cement hardens and is ultimately responsible of concrete performances. This hydration product is a cohesive nano-scale gel, whose structure and mechanics are still poorly understood, in spite of its practical importance. Here we review some of the open questions for this fascinating material and a statistical physics approach recently developed, which allows us to investigate the gel formation under the out-of-equilibrium conditions typical of cement hydration and the role of the nano-scale structure in C-S-H mechanics upon hardening. Our approach unveils how some distinctive features of the kinetics of cement hydration can be related to changes in the morphology of the gels and elucidates the role of nano-scale mechanical heterogeneities in the hardened C-S-H.

  8. Evaluation of Calcium Silicate Cement Bond Strength after Using ...

    African Journals Online (AJOL)

    2018-01-24

    Jan 24, 2018 ... Two‑way ANOVA analysis of variance and post hoc Tukey tests were used for analyses (P= 0.05). Results: The highest push‑out bond strength was observed in the Biodentine ..... Effect of blood contamination on the retention characteristics of two endodontic biomaterials in simulated furcation perforations.

  9. Development of a fully injectable calcium phosphate cement for ...

    Indian Academy of Sciences (India)

    Unknown

    2003-01-27

    Jan 27, 2003 ... fracture fixation in orthopedics and vertebroplasty in spi- nal surgery, filling root canals and sealing endodontic perforations in dentistry. Acknowledgements. Thanks are due to Dr T V Kumari, Mr Jacob Beboy, Mr. P R Hari and Mrs C Radhakumari for conducting the various tests and analyses. The authors ...

  10. 76 FR 76760 - Gray Portland Cement and Cement Clinker From Japan

    Science.gov (United States)

    2011-12-08

    ... Portland Cement and Cement Clinker From Japan Determination On the basis of the record \\1\\ developed in the... antidumping duty order on gray Portland cement and cement clinker from Japan would be likely to lead to... the Commission are contained in USITC Publication 4281 (December 2011), entitled Gray Portland Cement...

  11. 21 CFR 888.4200 - Cement dispenser.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cement dispenser. 888.4200 Section 888.4200 Food... DEVICES ORTHOPEDIC DEVICES Surgical Devices § 888.4200 Cement dispenser. (a) Identification. A cement dispenser is a nonpowered syringe-like device intended for use in placing bone cement (§ 888.3027) into...

  12. Development and Characterization of Biphasic Hydroxyapatite/β-TCP Cements.

    Science.gov (United States)

    Gallinetti, Sara; Canal, Cristina; Ginebra, Maria-Pau; Ferreira, J

    2014-04-01

    Biphasic calcium phosphate bioceramics composed of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) have relevant properties as synthetic bone grafts, such as tunable resorption, bioactivity, and intrinsic osteoinduction. However, they have some limitations associated to their condition of high-temperature ceramics. In this work self-setting Biphasic Calcium Phosphate Cements (BCPCs) with different HA/β-TCP ratios were obtained from self-setting α-TCP/β-TCP pastes. The strategy used allowed synthesizing BCPCs with modulated composition, compressive strength, and specific surface area. Due to its higher solubility, α-TCP was fully hydrolyzed to a calcium-deficient HA (CDHA), whereas β-TCP remained unreacted and completely embedded in the CDHA matrix. Increasing amounts of the non-reacting β-TCP phase resulted in a linear decrease of the compressive strength, in association to the decreasing amount of precipitated HA crystals, which are responsible for the mechanical consolidation of apatitic cements. Ca2+ release and degradation in acidic medium was similar in all the BCPCs within the timeframe studied, although differences might be expected in longer term studies once β-TCP, the more soluble phase was exposed to the surrounding media.

  13. Injectability, microstructure and release properties of sodium fusidate-loaded apatitic cement as a local drug-delivery system.

    Science.gov (United States)

    Noukrati, Hassan; Cazalbou, Sophie; Demnati, Imane; Rey, Christian; Barroug, Allal; Combes, Christèle

    2016-02-01

    The introduction of an antibiotic, sodium fusidate (SF), into the liquid phase of calcium carbonate-calcium phosphate (CaCO3-CaP) bone cement was evaluated, considering the effect of the liquid to powder ratio (L/P) on the composition and microstructure of the set cement and the injectability of the paste. In all cases, we obtained set cements composed mainly of biomimetic carbonated apatite analogous to bone mineral. With this study, we evi-denced a synergistic effect of the L/P ratio and SF presence on the injectability (i.e., the filter-pressing pheno-menon was suppressed) and the setting time of the SF-loaded cement paste compared to reference cement (without SF). In addition, the in vitro study of SF release, according to the European Pharmacopoeia recommendations, showed that, regardless of the L/P ratio, the cement allowed a sustained release of the antibiotic over 1month in sodium chloride isotonic solution at 37°C and pH7.4; this release is discussed considering the microstructure characteristics of SF-loaded cements (i.e., porosity, pore-size distribution) before and after the release test. Finally, modelling antibiotic release kinetics with several models indicated that the SF release was controlled by a diffusion mechanism. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Effect of different endodontic sealers and time of cementation on push-out bond strength of fiber posts.

    Science.gov (United States)

    Vilas-Boas, Danielle Araújo; Grazziotin-Soares, Renata; Ardenghi, Diego Machado; Bauer, José; de Souza, Patrícia Oliveira; de Miranda Candeiro, George Táccio; Maia-Filho, Etevaldo Matos; Carvalho, Ceci Nunes

    2017-10-11

    This study aims to evaluate the effect of different endodontic sealers (epoxy resin, eugenol, and bioceramic/calcium silicate-based) and the time of cementation (immediately or 7 days after canal obturation) on the bond strength of a fiberglass post cemented with RelyX™ ARC. Eighty-four premolars were instrumented and divided into groups (n = 12) according to the sealer and the time of post cementation: Endofill (EN), Endosequence BC Sealer (BC), and AH Plus (AH) had immediately fiber post cementation; EN7, BC7, and AH7 had post cementation after 7 days; and control group (C) had fiber post cementation without endodontic sealer. Each post space of the root was cut into slices and submitted to push-out test. Failure mode was assessed. Two-way ANOVA, Tukey's, and Dunnett's tests were used for statistical analysis (α = 5%). The type of endodontic sealer (p post cementation (p = 0.038), and the interaction sealer time (p = 0.002) had negative influence on bond strength of fiberglass posts cemented with RelyX™ ARC. AH promoted the highest bond strength mean values (21.20 MPa immediately and 15.54 MPa at 7 days). EN (9.75 MPa immediately and 13.15 MPa at 7 days) and BC (10.43 MPa immediately and 5.73 MPa at 7 days) had lower bond strength than AH, regardless the time of cementation. AH was the best sealer to obturate the root canal when fiberglass cementation with resin-based cement is planned. The correct choice of an endodontic sealer and the adequate time of post cementation may avoid post dislocation caused by low bond strength to dentin.

  15. Comparative fatigue behavior of different bone cements.

    Science.gov (United States)

    Gates, E I; Carter, D R; Harris, W H

    1984-10-01

    Tensile and fatigue studies were performed on four different preparations of acrylic bone cement: (1) surgical Simplex-P inserted into molds in the dough stage, (2) Zimmer Low Viscosity Cement (LVC) inserted in the liquid phase, (3) an experimental cement inserted in the dough phase, and (4) the same experimental cement inserted in the liquid phase. The void characteristics of the cements appeared to dictate their mechanical performance. While tests revealed no difference in the tensile strengths of the four cement preparations, small but statistically significant differences in mean fatigue life were observed. The experimental cement used in the dough stage exhibited superior fatigue characteristics when compared with Simplex and LVC. LVC had the poorest mechanical properties of the four cement groups. Since the specimen preparation procedures can markedly influence the cement void characteristics and, consequently, the mechanical properties, general statements about different cement types are offered with considerable reservations.

  16. Calcium paradox and calcium entry blockers

    NARCIS (Netherlands)

    Ruigrok, T.J.C.; Slade, A.M.; Nayler, W.G.; Meijler, F.L.

    1984-01-01

    Reperfusion of isolated hearts with calcium-containing solution after a short period of calcium-free perfusion results in irreversible cell damage (calcium paradox). This phenomenon is characterized by an excessive influx of calcium into the cells, the rapid onset of myocardial contracture,

  17. Self-Setting Calcium Orthophosphate Formulations

    Science.gov (United States)

    Dorozhkin, Sergey V.

    2013-01-01

    In early 1980s, researchers discovered self-setting calcium orthophosphate cements, which are bioactive and biodegradable grafting bioceramics in the form of a powder and a liquid. After mixing, both phases form pastes, which set and harden forming either a non-stoichiometric calcium deficient hydroxyapatite or brushite. Since both of them are remarkably biocompartible, bioresorbable and osteoconductive, self-setting calcium orthophosphate formulations appear to be promising bioceramics for bone grafting. Furthermore, such formulations possess excellent molding capabilities, easy manipulation and nearly perfect adaptation to the complex shapes of bone defects, followed by gradual bioresorption and new bone formation. In addition, reinforced formulations have been introduced, which might be described as calcium orthophosphate concretes. The discovery of self-setting properties opened up a new era in the medical application of calcium orthophosphates and many commercial trademarks have been introduced as a result. Currently such formulations are widely used as synthetic bone grafts, with several advantages, such as pourability and injectability. Moreover, their low-temperature setting reactions and intrinsic porosity allow loading by drugs, biomolecules and even cells for tissue engineering purposes. In this review, an insight into the self-setting calcium orthophosphate formulations, as excellent bioceramics suitable for both dental and bone grafting applications, has been provided. PMID:24956191

  18. Alternative Fuels in Cement Production

    DEFF Research Database (Denmark)

    Larsen, Morten Boberg

    The substitution of alternative for fossil fuels in cement production has increased significantly in the last decade. Of these new alternative fuels, solid state fuels presently account for the largest part, and in particular, meat and bone meal, plastics and tyre derived fuels (TDF) accounted...... for the most significant alternative fuel energy contributors in the German cement industry. Solid alternative fuels are typically high in volatile content and they may differ significantly in physical and chemical properties compared to traditional solid fossil fuels. From the process point of view......, considering a modern kiln system for cement production, the use of alternative fuels mainly influences 1) kiln process stability (may accelerate build up of blockages preventing gas and/or solids flow), 2) cement clinker quality, 3) emissions, and 4) decreased production capacity. Kiln process stability...

  19. Nanomechanical characterization of cement-based pastes enriched with SiO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zyganitidis, I., E-mail: izyga@auth.gr [Laboratory for Thin Films Nanosystems and Nanometrology, Physics Department, Aristotle University of Thessaloniki (Greece); Stefanidou, M. [Laboratory of Building Materials, Department of Civil Engineering, Aristotle University of Thessaloniki (Greece); Kalfagiannis, N.; Logothetidis, S. [Laboratory for Thin Films Nanosystems and Nanometrology, Physics Department, Aristotle University of Thessaloniki (Greece)

    2011-11-25

    Highlights: > In this study we examine the relation between microstructural, nanomechanical and surface properties of cement based pastes. > Addition of SiO{sub 2} nanoparticles to cement pastes leads to more compact structures with increased calcium crystal size. > Changes in microstructure led to the reduction of the mechanical properties of samples. - Abstract: Microstructural and nanomechanical surface properties of cement based pastes were experimentally investigated. Samples were prepared from CEMI42.5 cement, with water to cement ratio equal to 0.5 and enriched with SiO{sub 2} nanoparticles (d = 14 nm), with low concentration ranging from 0% up to 0.5% (by weight of binder). X-rays diffraction (XRD) patterns revealed a linear increase of crystal size of calcium hydrate (CH) products with the addition of nanoparticles, while scanning electron microscopy (SEM) images showed a denser microstructure with more defined grains for the higher SiO{sub 2} nanoparticles concentration. Atomic force microscopy (AFM) studies of samples after the grinding/polishing process indicated a strong dependence of surface roughness with the CH crystallite mean size and the materials mechanical properties. Finally, statistical analysis of nanoindentation mapping data revealed a decrease of elastic modulus with the increase of nanoparticles concentration.

  20. Microstructural Origins of Cement Paste Degradation by External Sulfate Attack.

    Science.gov (United States)

    Feng, Pan; Garboczi, Edward J; Miao, Changwen; Bullard, Jeffrey W

    2015-10-15

    A microstructure model has been applied to simulate near-surface degradation of portland cement paste in contact with a sodium sulfate solution. This new model uses thermodynamic equilibrium calculations to guide both compositional and microstructure changes. It predicts localized deformation and the onset of damage by coupling the confined growth of new solids with linear thermoelastic finite element calculations of stress and strain fields. Constrained ettringite growth happens primarily at the expense of calcium monosulfoaluminate, carboaluminate and aluminum-rich hydrotalcite, if any, respectively. Expansion and damage can be mitigated chemically by increasing carbonate and magnesium concentrations or microstructurally by inducing a finer dispersion of monosulfate.

  1. In Vivo Osteogenic Potential of Biomimetic Hydroxyapatite/Collagen Microspheres: Comparison with Injectable Cement Pastes

    Science.gov (United States)

    Manzanares, Maria-Cristina; Ginebra, Maria-Pau; Franch, Jordi

    2015-01-01

    The osteogenic capacity of biomimetic calcium deficient hydroxyapatite microspheres with and without collagen obtained by emulsification of a calcium phosphate cement paste has been evaluated in an in vivo model, and compared with an injectable calcium phosphate cement with the same composition. The materials were implanted into a 5 mm defect in the femur condyle of rabbits, and bone formation was assessed after 1 and 3 months. The histological analysis revealed that the cements presented cellular activity only in the margins of the material, whereas each one of the individual microspheres was covered with osteogenic cells. Consequently, bone ingrowth was enhanced by the microspheres, with a tenfold increase compared to the cement, which was associated to the higher accessibility for the cells provided by the macroporous network between the microspheres, and the larger surface area available for osteoconduction. No significant differences were found in terms of bone formation associated with the presence of collagen in the materials, although a more extensive erosion of the collagen-containing microspheres was observed. PMID:26132468

  2. Design and properties of novel gallium-doped injectable apatitic cements.

    Science.gov (United States)

    Mellier, Charlotte; Fayon, Franck; Boukhechba, Florian; Verron, Elise; LeFerrec, Myriam; Montavon, Gilles; Lesoeur, Julie; Schnitzler, Verena; Massiot, Dominique; Janvier, Pascal; Gauthier, Olivier; Bouler, Jean-Michel; Bujoli, Bruno

    2015-09-01

    Different possible options were investigated to combine an apatitic calcium phosphate cement with gallium ions, known as bone resorption inhibitors. Gallium can be either chemisorbed onto calcium-deficient apatite or inserted in the structure of β-tricalcium phosphate, and addition of these gallium-doped components into the cement formulation did not significantly affect the main properties of the biomaterial, in terms of injectability and setting time. Under in vitro conditions, the amount of gallium released from the resulting cement pellets was found to be low, but increased in the presence of osteoclastic cells. When implanted in rabbit bone critical defects, a remodeling process of the gallium-doped implant started and an excellent bone interface was observed. The integration of drugs and materials is a growing force in the medical industry. The incorporation of pharmaceutical products not only promises to expand the therapeutic scope of biomaterials technology but to design a new generation of true combination products whose therapeutic value stem equally from both the structural attributes of the material and the intrinsic therapy of the drug. In this context, for the first time an injectable calcium phosphate cement containing gallium was designed with properties suitable for practical application as a local delivery system, implantable by minimally invasive surgery. This important and original paper reports the design and in-depth chemical and physical characterization of this groundbreaking technology. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  3. Mechanical and microscopic properties of API G cement after exposure to supercritical CO2

    Directory of Open Access Journals (Sweden)

    C. C. Kuo

    2017-01-01

    Full Text Available An experiment on API G-level (American Petroleum Institute cement is conducted after curing under a supercritical carbon dioxide environment. Cement paste is prepared first to generate a uniaxial compressive specimen, after which the specimen is exposed to the supercritical carbon dioxide environment (temperature = 70°C; pressure = 20 MPa for curing at different numbers of days (7 - 84 days. The physical and chemical changes in the cement are subsequently simulated at 1500 - 2000 m below the injection well during CO2 sequestration. Results show that the uniaxial compressive strength of the specimen decreases as the number of curing days increases, indicating that the specimen sustains considerable damage when cured under humid environments. This result also implies a declining trend in the longitudinal and transverse waves of the cured specimen. Based on the material analytical results we determine that carbon dioxide reacts with the calcium hydroxide, water and calcium silicate in the cement. The carbon dioxide is then converted into calcium carbonate, resulting in different degrees of carbonization depending on the number of curing days.

  4. Setting time and sealing ability of alpha-tricalcium phosphate cement containing titanic oxide.

    Science.gov (United States)

    Yoshikawa, M; Terada, Y; Toda, T

    1998-10-01

    We developed a new type of calcium phosphate cement for clinical use in endodontics as a root canal sealer or pulp cupping agent. The solid phase of the sealer is composed of 70% of alpha-tricalcium phosphate (alpha-TCP) and 30% of titanic oxide (TiO2), and the liquid phase is 37% citric acid, 5% tannic acid and 58% distilled water. TiO2 was added to control setting time and handling of the cement. We used commercially available calcium phosphate root canal sealer as a control. ISO standards specify that new endodontic products should be examined thoroughly before clinical use. It is important to carry out in vitro cytotoxicity and in vivo histocompatibility tests. We first did in vitro test of setting time and root canal sealing ability of the cement. We found that this developed calcium phosphate cement had an appropriate setting time and excellent sealing ability as a root canal sealer, and concluded that it was suitable for clinical use as a root canal sealer.

  5. Cement pulmonary embolism after vertebroplasty.

    Science.gov (United States)

    Sifuentes Giraldo, Walter Alberto; Lamúa Riazuelo, José Ramón; Gallego Rivera, José Ignacio; Vázquez Díaz, Mónica

    2013-01-01

    In recent years, the use of vertebral cementing techniques for vertebroplasty and kyphoplasty has spread for the treatment of pain associated with osteoporotic vertebral compression fractures. This is also associated with the increased incidence of complications related with these procedures, the most frequent being originated by leakage of cementation material. Cement can escape into the vertebral venous system and reach the pulmonary circulation through the azygous system and cava vein, producing a cement embolism. This is a frequent complication, occurring in up to 26% of patients undergoing vertebroplasty but, since most patients have no clinical or hemodynamical repercussion, this event usually goes unnoticed. However, some serious, and even fatal cases, have been reported. We report the case of a 74-year-old male patient who underwent vertebroplasty for persistent pain associated with osteoporotic L3 vertebral fracture and who developed a cement leak into the cava vein and right pulmonary artery during the procedure. Although he developed a pulmonary cement embolism, the patient remained asymptomatic and did not present complications during follow-up. Copyright © 2012 Elsevier España, S.L. All rights reserved.

  6. Coronary Calcium Scan

    Science.gov (United States)

    ... Back To Health Topics / Coronary Calcium Scan Coronary Calcium Scan Also known as Calcium Scan Test A coronary calcium scan is a CT scan of your heart that detects and measures the amount of calcium in the walls of your coronary arteries. Overview ...

  7. Ecological indices of manufacture of Portland cement clinker and production of the dolomite clinker

    Directory of Open Access Journals (Sweden)

    Vinnichenko Varvara

    2017-01-01

    Full Text Available It is shown that the production of dolomite clinker in comparison with that of Portland cement is environmentally appropriate. When calcining dolomite for cementitious binder, the pollution of the atmosphere by carbon dioxide is reduced due to its isolation during decarbonization reactions of calcium carbonates. Reducing fuel consumption for clinker burning provides less carbon dioxide emissions from combustion products. Reducing the firing temperature creates obstacles to the formation of nitrogen oxides. The production of binders from dolomite in comparison with the production of Portland cement helps to protect the environment from contamination

  8. An Investigation into the Properties and Microstructure of Cement Mixtures Modified with Cellulose Nanocrystal

    Science.gov (United States)

    Flores, Jessica; Kamali, Mahsa; Ghahremaninezhad, Ali

    2017-01-01

    This paper aims to examine the effect of cellulose nanocrystals (CNC) on the hydration, transport behavior, and microstructure of cement mixtures. The addition of CNC delayed hydration at an early age but improved hydration at later ages. A small increase in the electrical resistivity of the cement mixtures with CNC was observed. Statistical nanoindentation showed a small tendency to a larger volume fraction of high density calcium-silicate-hydrate (C-S-H) and a smaller volume fraction of low-density C-S-H in the mixture with CNC. PMID:28772857

  9. Effect of Limestone Powder on Acid Attack Characteristics of Cement Pastes

    Directory of Open Access Journals (Sweden)

    Shuhua LIU

    2014-12-01

    Full Text Available The acid resistance of cement pastes containing limestone powder with two different water-binder (w/b ratios exposed to acetic (pH = 4 and sulfuric acid (pH = 2 solutions respectively were investigated in this paper. Limestone powder, fly ash and silica fume were also added to the cement paste mixture at different proportions. Static and flowing aqueous environments were set in this experiment. Strength and microstructure of the pastes after acid attack were investigated by using strength test, X-ray diffractometer (XRD and scanning electron microscopy (SEM. The experimental results show that the erosion degree depends not only on pH value of the solution and w/b ratio of the pastes, but also on the content of limestone powder. Acetic acid reacts with calcium hydroxide and carbonate thus dissolving the pastes, while sulfuric acid consumed calcium hydroxide, and generated gypsum and ettringite. The consumption of calcium hydroxide in the flowing solution group is higher than that in the static solution because the flowing sulfuric acid solution has negative effect upon the gypsum crystallization. Fly ash and silica fume are beneficial to limestone cement paste because of the less calcium hydroxide formation, which is among the hydrates vulnerable to acid erosion. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6231

  10. Calcium source (image)

    Science.gov (United States)

    Getting enough calcium to keep bones from thinning throughout a person's life may be made more difficult if that person has ... as a tendency toward kidney stones, for avoiding calcium-rich food sources. Calcium deficiency also effects the ...

  11. Calcium and bones (image)

    Science.gov (United States)

    Calcium is one of the most important minerals for the growth, maintenance, and reproduction of the human ... body, are continually being re-formed and incorporate calcium into their structure. Calcium is essential for the ...

  12. Calcium Pyrophosphate Deposition (CPPD)

    Science.gov (United States)

    ... Patient / Caregiver Diseases & Conditions Calcium Pyrophosphate Deposition (CPPD) Calcium Pyrophosphate Deposition (CPPD) Fast Facts The risk of ... young people, too. Proper diagnosis depends on detecting calcium pyrophosphate crystals in the fluid of an affected ...

  13. Calcium blood test

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003477.htm Calcium blood test To use the sharing features on this page, please enable JavaScript. The calcium blood test measures the level of calcium in the blood. ...

  14. The chemical constitution and biocompatibility of accelerated Portland cement for endodontic use.

    Science.gov (United States)

    Camilleri, J; Montesin, F E; Di Silvio, L; Pitt Ford, T R

    2005-11-01

    To evaluate the biocompatibility of mineral trioxide aggregate and accelerated Portland cement and their eluants by assessing cell metabolic function and proliferation. The chemical constitution of grey and white Portland cement, grey and white mineral trioxide aggregate (MTA) and accelerated Portland cement produced by excluding gypsum from the manufacturing process (Aalborg White) was determined using both energy dispersive analysis with X-ray and X-ray diffraction analysis. Biocompatibility of the materials was assessed using a direct test method where cell proliferation was measured quantitatively using Alamar Blue dye and an indirect test method where cells were grown on material elutions and cell proliferation was assessed using methyltetrazolium assay as recommended by the International standard guidelines, ISO 10993-Part 5 for in vitro testing. The chemical constitution of all the materials tested was similar. Indirect studies of the eluants showed an increase in cell activity after 24 h compared with the control in culture medium (Pbismuth oxide to the accelerated Portland cement did not interfere with biocompatibility. The new accelerated Portland cement showed similar results. Cell growth was poor when seeded in direct contact with the test cements. However, the elution made up of calcium hydroxide produced during the hydration reaction was shown to induce cell proliferation.

  15. Application of antifungal CFB to increase the durability of cement mortar.

    Science.gov (United States)

    Park, Jong-Myong; Park, Sung-Jin; Kim, Wha-Jung; Ghim, Sa-Youl

    2012-07-01

    Antifungal cement mortar or microbiological calcium carbonate precipitation on cement surface has been investigated as functional concrete research. However, these research concepts have never been fused with each other. In this study, we introduced the antifungal calciteforming bacteria (CFB) Bacillus aryabhattai KNUC205, isolated from an urban tunnel (Daegu, South Korea). The major fungal deteriogens in urban tunnel, Cladosporium sphaerospermum KNUC253, was used as a sensitive fungal strain. B. aryabhattai KNUC205 showed CaCO3 precipitation on B4 medium. Cracked cement mortar pastes were made and neutralized by modified methods. Subsequently, the mixture of B. aryabhattai KNUC205, conidiospore of C. sphaerospermum KNUC253, and B4 agar was applied to cement cracks and incubated at 18 degrees C for 16 days. B. aryabhattai KNUC205 showed fungal growth inhibition against C. sphaerospermum. Furthermore, B. aryabhattai KNUC205 showed crack remediation ability and water permeability reduction of cement mortar pastes. Taken together, these results suggest that the CaCO3 precipitation and antifungal properties of B. aryabhattai KNUC205 could be used as an effective sealing or coating material that can also prevent deteriorative fungal growth. This study is the first application and evaluation research that incorporates calcite formation with antifungal capabilities of microorganisms for an environment-friendly and more effective protection of cement materials. In this research, the conception of microbial construction materials was expanded.

  16. Evaluating the cement stabilization of arsenic-bearing iron wastes from drinking water treatment.

    Science.gov (United States)

    Clancy, Tara M; Snyder, Kathryn V; Reddy, Raghav; Lanzirotti, Antonio; Amrose, Susan E; Raskin, Lutgarde; Hayes, Kim F

    2015-12-30

    Cement stabilization of arsenic-bearing wastes is recommended to limit arsenic release from wastes following disposal. Such stabilization has been demonstrated to reduce the arsenic concentration in the Toxicity Characteristic Leaching Procedure (TCLP), which regulates landfill disposal of arsenic waste. However, few studies have evaluated leaching from actual wastes under conditions similar to ultimate disposal environments. In this study, land disposal in areas where flooding is likely was simulated to test arsenic release from cement stabilized arsenic-bearing iron oxide wastes. After 406 days submersed in chemically simulated rainwater, wastes. Presenting the first characterization of cement stabilized waste using μXRF, these results revealed the majority of arsenic in cement stabilized waste remained associated with iron. This distribution of arsenic differed from previous observations of calcium-arsenic solid phases when arsenic salts were stabilized with cement, illustrating that the initial waste form influences the stabilized form. Overall, cement stabilization is effective for arsenic-bearing wastes when acidic conditions can be avoided. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. The behavior of novel hydrophilic composite bone cements in simulated body fluids.

    Science.gov (United States)

    Boesel, Luciano F; Fernandes, Maria H V; Reis, Rui L

    2004-08-15

    Composite bone cements were formulated with bioactive glass (MgO--SiO(2)--3CaO. P(2)O(5)) as the filler and hydrophilic matrix. The matrix was composed of a starch/cellulose acetate blend (SCA) as the solid component and a mixture of methylmethacrylate/acrylic acid (MMA/AA) as the liquid component. The curing parameters, mechanical properties, and bioactive behavior of these composite cements were determined. The addition of up to 30 wt % of glass improved both compressive modulus and yield strength and kept the maximum curing temperature at the same value presented by a typical acrylic-based commercial formulation. The lack of a strongly bonded interface (because no coupling agent was used) had important effects on the swelling and mechanical properties of the novel bone cements. However, bone cements containing AA did not show a bioactive behavior, because of the deleterious effect of this monomer on the calcium phosphate precipitation on the polymeric surfaces. Formulations without AA were prepared with MMA or 2-hydroxyethyl methacrylate (HEMA) as the liquid component. Only these formulations could form an apatite-like layer on their surface. These systems, therefore, are very promising: They are bioactive, hydrophilic, partially degradable, and present interesting mechanical properties. This combination of properties could facilitate the release of bioactive agents from the cement, allow bone ingrowth in the cement, and induce a press-fitting effect, improving the interfaces with both the prosthesis and the bone. Copyright 2004 Wiley Periodicals, Inc.

  18. Cement with silica fume and granulated blast-furnace slag: strength behavior and hydration

    Directory of Open Access Journals (Sweden)

    Bonavetti, V. L.

    2014-09-01

    Full Text Available This paper analyses the influence of portland cement replacement by silica fume (up to 10% and/or granulated blast furnace slag (up to 70% on the hydration cement (XRD, heat of hydration, non evaporable water content and calcium hydroxide content curing under sealed conditions and their effect on the mechanical strength. The obtained results indicate that binary cements containing silica fume and ternary cements there was a significant increase of hydration rate at early age. At later ages, most of studied cements have an equivalent or greater strength that those obtained in the plain portland cement.En este trabajo se analiza la influencia de la incorporación al cemento portland de humo de sílice (hasta 10% y/o escoria granulada de alto horno (hasta 70% sobre la hidratación (DRX, calor de hidratación, contenido de agua no evaporable y de hidróxido de calcio, bajo condiciones de curado sellado y su incidencia sobre la resistencia mecánica. Los resultados obtenidos indican que en los cementos binarios con humo de sílice y en los cementos ternarios se produce un importante aumento de la velocidad de hidratación en las primeras edades, mientras que a edades más avanzadas la mayor parte del dominio estudiado alcanza o supera la resistencia obtenida por el cemento portland sin adición.

  19. The effect of different composition sols on change of structure and properties of cement stone

    Directory of Open Access Journals (Sweden)

    URKHANOVA Larisa Alekseevna

    2016-12-01

    compositions is a result of change of its structure. Electronic and microscopic analysis showed that use of sols of different composition as modifiers leads to compaction of microstructure of cement stone and formation of difficult compounds of sulfur and chromium with hydrated calcium silicates.

  20. Evolution of cement based materials in a repository for radioactive waste and their chemical barrier function

    Energy Technology Data Exchange (ETDEWEB)

    Kienzler, Bernhard; Metz, Volker; Schlieker, Martina; Bohnert, Elke [Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen (Germany). Inst. fuer Nukleare Entsorgung (INE)

    2015-07-01

    The use of cementitious materials in nuclear waste management is quite widespread. It covers the solidification of low/intermediate-level liquid as well as solid wastes (e.g. laboratory wastes) and serves as shielding. For both high-level and intermediate-low level activity repositories, cement/concrete likewise plays an important role. It is used as construction material for underground and surface disposals, but more importantly it serves as barrier or sealing material. For the requirements of waste conditioning, special cement mixtures have been developed. These include special mixtures for the solidification of evaporator concentrates, borate binding additives and for spilling solid wastes. In recent years, low-pH cements were strongly discussed especially for repository applications, e.g. (Celine CAU DIT COUMES 2008; Garcia-Sineriz, et al. 2008). Examples for relevant systems are Calcium Silicate Cements (ordinary Portland cement (OPC) based) or Calcium Aluminates Cements (CAC). Low-pH pore solutions are achieved by reduction of the portlandite content by partial substitution of OPC by mineral admixtures with high silica content. The blends follow the pozzolanic reaction consuming Ca(OH){sub 2}. Potential admixtures are silica fume (SF) and fly ashes (FA). In these mixtures, super plasticizers are required, consisting of polycarboxilate or naphthalene formaldehyde as well as various accelerating admixtures (Garcia-Sineriz, et al. 2008). The pH regime of concrete/cement materials may stabilize radionuclides in solution. Newly formed alteration products retain or release radionuclides. An important degradation product of celluloses in cement is iso-saccharin acid. According to Glaus 2004 (Glaus and van Loon 2004), it reacts with radionuclides forming dissolved complexes. Apart from potentially impacting radionuclide solubility limitations, concrete additives, radionuclides or other strong complexants compete for surface sites for sorbing onto cement phases. In

  1. Degradable borate glass polyalkenoate cements.

    Science.gov (United States)

    Shen, L; Coughlan, A; Towler, M; Hall, M

    2014-04-01

    Glass polyalkenoate cements (GPCs) containing aluminum-free borate glasses having the general composition Ag2O-Na2O-CaO-SrO-ZnO-TiO2-B2O3 were evaluated in this work. An initial screening study of sixteen compositions was used to identify regions of glass formation and cement compositions with promising rheological properties. The results of the screening study were used to develop four model borate glass compositions for further study. A second round of rheological experiments was used to identify a preferred GPC formulation for each model glass composition. The model borate glasses containing higher levels of TiO2 (7.5 mol %) tended to have longer working times and shorter setting times. Dissolution behavior of the four model GPC formulations was evaluated by measuring ion release profiles as a function of time. All four GPC formulations showed evidence of incongruent dissolution behavior when considering the relative release profiles of sodium and boron, although the exact dissolution profile of the glass was presumably obscured by the polymeric cement matrix. Compression testing was undertaken to evaluate cement strength over time during immersion in water. The cements containing the borate glass with 7.5 mol % TiO2 had the highest initial compressive strength, ranging between 20 and 30 MPa. No beneficial aging effect was observed-instead, the strength of all four model GPC formulations was found to degrade with time.