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  • 1.
    Carlson, Johan
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nilsson, M
    Biomaterials Lab, Department of Orthopaedics, Biomedical Centre, Lund.
    Fernández, E
    Research Centre in Biomedical Engineering, Polytechnical University of Catalonia, Barcelona.
    Planell, J. A.
    Research Centre in Biomedical Engineering, Polytechnical University of Catalonia, Barcelona.
    Monitoring the setting of calcium-based bone cements using pulse-echo ultrasound2002In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 13, no 12, p. 1135-1141Article in journal (Refereed)
    Abstract [en]

    We present a new technique, based on pulse-echo ultrasound, for monitoring the entire setting process of injectable bone cement. This research has been motivated by the lack of satisfying standards. The main problem with existing standards is the subjectivity, which leads to poor reproducibility. Because of this the results are not comparable between different research groups. A strong advantage with the proposed technique is that if low-intensity ultrasound is used, it provides a non-destructive analysis method. Once the cement paste has been applied to the measurement cell, no manipulation is needed throughout the entire setting process. The problem of the ultrasound affecting the setting of certain cement materials has been investigated, and solutions are discussed. The propagation of ultrasound is temperature-dependent, and therefore a technique for automatic compensation for temperature variations is discussed briefly. The testing was performed on -calcium sulfate hemihydrate (CSH) and mixtures of CSH and -tricalcium phosphate (-TCP). The results show that the acoustic properties of the cement are strongly correlated with the setting time, the density, and the adiabatic bulk modulus. The measured initial and final setting times agree well with the Gillmore needles standard. An important difference compared to the standards, is that the technique presented here allows the user to follow the entire setting process on-line.

  • 2.
    Emami, Nazanin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Söderholm, Karl-Johan M.
    Department of Dental Biomaterials, University of Florida.
    Influence of light-curing procedures and photo-initiator/co-initiator composition on the degree of conversion of light-curing resins2005In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 16, no 1, p. 47-52Article in journal (Refereed)
    Abstract [en]

    Objective: The hypothesis that the degree and rate of conversion can be modified favourably by using different light-curing procedures and different photo initiator/co-initiator combinations was tested.Method: A photo-initiator (0.02 mM/g resin); either camphorquinone (CQ) or 1-phenyl-1,2-propanedione (PPD), was mixed with bisGMA:TEGDMA (50:50 by weight). In addition, a co-initiator (0.04 mM/g resin); either N,N-dimethyl-p-aminobenzoic acid ethylester (DABE), N,N-cyanoethylmethylaniline (CEMA), or 2-dimethylaminoethyl methacrylate (DMAEMA), was added. These six combinations were subjected to three curing conditions (standard curing, soft-start curing or LED curing). The conversion levels (DC) were determined with differential scanning calorimetry (DSC). The DSC results were analysed using a general linear model (GLM) and Duncans multiple range test and regular t-test.Results: The fastest conversion initially was obtained by standard curing, followed by LED curing and soft-start curing. After 40 s of curing, conventional curing and soft-start curing produced a higher DC than LED curing. However, strong interactions occurred between the different variables (curing method, initiator and co-initiator). Initially, CQ was more efficient than PPD, but after 40 s, this difference was insignificant.Conclusion: By using soft-start curing and an appropriate photo initiator/co-initiator combination it is possible to achieve slow curing and a high DC at within a curing time of 40 s.

  • 3.
    Vlad, M. D.
    et al.
    Faculty of Medical Bioengineering, Gr. T. Popa University of Medicine and Pharmacy, Str. Kogalniceanu 9-13, 700454 Iasi.
    González, L.
    Division of Bioengineering & Biomaterials, Interdepartment Research Group for the Applied Scientific Collaboration (IRGASC), Technical University of Catalonia (UPC), Avda. Diagonal 647, 08028 Barcelona.
    Gómez, S.
    Division of Bioengineering & Biomaterials, Interdepartment Research Group for the Applied Scientific Collaboration (IRGASC), Technical University of Catalonia (UPC), Avda. Diagonal 647, 08028 Barcelona.
    López, J.
    Division of Bioengineering & Biomaterials, Interdepartment Research Group for the Applied Scientific Collaboration (IRGASC), Technical University of Catalonia (UPC), Avda. Diagonal 647, 08028 Barcelona.
    Carlson, Johan E.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Fernández, E.
    Department of Materials Science and Metallurgical Engineering, Technical University of Catalonia (UPC), Avda. Diagonal 647, 08028 Barcelona.
    Ultrasound monitoring of the setting of calcium-based bone cements2012In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 23, no 7, p. 1563-1568Article in journal (Refereed)
    Abstract [en]

    In this study, the setting of calcium-sulphate (CS) and -phosphate (CP) based bone cements (BCs) was monitored by ultrasound. The objective was to link acoustic and material properties of ceramic-based BCs from the early stages of the cement curing process. The powder phase of the CS-cement consisted of CS hemihydrate; the CP-cement was a mixture of alpha-tricalcium phosphate, CS dihydrate and hydroxyapatite. For the CS-cement, the acoustic impedance z c(t), the speed of sound c c(t) and the density ρc(t) were measured at the interval of liquid-to-powder ratios LPRs from 0.20 to 3.00 ml/g. For the CP-cement, the acoustic characteristics obtained were the z c(t) and the reflection coefficient R p,c(t), and the LPRs ranged from 0.30 to 0.40 ml/g. The resulting acoustic properties indicated that CP- and CS-cements exhibited distinctly different curing behaviour; while CS-cement expanded, CP-cement shrank with time.

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