Influence of the partial substitution of CaO with MgO on the thermal properties and in vitro reactivity of the bioactive glass S53P4

Jonathan Massera, Leena Hupa, Mikko Hupa

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    Abstract

    The influence of up to 4 mol% substitution of MgO for CaO on the properties of the bioactive glass S53P4 was studied. Thermal analysis, hot stage microscopy and X-ray diffractometry were utilized to measure the thermal properties and the crystallization characteristics of the glasses. The in-vitro bioactivity was measured by immersing the glasses for 4 h to one week in simulated body fluid. The formation of silica rich and hydroxyapatite layers was assessed from FTIR spectra analysis and SEM images of the glasses surface. Increasing substitution of MgO for CaO decreased the glass transition, the onset and endset of melting and the fusion temperatures. The activation energies for glass transition and crystallization also decreased from (790 +/- 30) to (407 +/- 30) kJ/mol and from (283 +/- 30) to (145 +/- 30) kJ/mol, respectively, indicating a decrease in bond length and an increase in bond strength with progressive MgO at the expense of CaO. All glasses dissolved identically in SBF during the first 24 h of immersion with subsequent formation of hydroxyapatite at the grain surfaces. The thickness of the surface layers decreased with increasing MgO content. For longer duration of immersion, the glasses with the highest MgO contents exhibited a slower reaction tendency, with simulated body fluid, than the Mg-free glass. These changes in the glass structure and in-vitro properties may be of interest for products from bioactive glasses with large surface area to volume ratio.
    Original languageUndefined/Unknown
    Pages (from-to)2701–2707
    Number of pages7
    JournalJournal of Non-Crystalline Solids
    Volume358
    Issue number18-19
    DOIs
    Publication statusPublished - 2012
    MoE publication typeA1 Journal article-refereed

    Keywords

    • Bioactive glasses
    • In-vitro bioactivity
    • Structural properties
    • Thermal properties

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