IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Biomaterials Tuesday Sessions
       Session BI-TuP

Paper BI-TuP8
Glass Ionomer Cements: Probing Uptake from Solution using Surface Sensitive Techniques

Tuesday, October 30, 2001, 5:30 pm, Room 134/135

Session: Surface Characterization and Non-Fouling Surfaces Poster Session
Presenter: F.H. Jones, University College London, UK
Authors: B.M. Hutton, University College London, UK
G. Palmer, University College London, UK
P.C. Hadley, University College London, UK
T.A. Steele, Millbrook Instruments Ltd., UK
A.J. Eccles, Millbrook Instruments Ltd., UK
R.W. Billington, Queen Mary, UK
G.J. Pearson, Queen Mary, UK
F.H. Jones, University College London, UK
Correspondent: Click to Email
Glass ionomer cements (GICs) are dental filling materials with the ability to take up ionic species (e.g. F@super -@) from solution and store them within the cement matrix for subsequent re-release. This offers the potential for controlled drug release in-vivo. Previously, ion uptake and release by such materials has been determined primarily by measuring ion concentration in solution.@footnote 1@ Although this approach provides useful data on the concentration of ionic species as a function of time, little is learned about the mechanism of uptake and release. In the current work, X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) have been used to examine ion uptake. Cements were analysed after the introduction of fluoride either by doping or by immersion in KF(aq) of various concentration. Immersion of a GIC based on poly(acrylic acid) and a calcium aluminosilicate glass was found to result in the formation of a calcium and fluoride rich surface layer, while doping by mixing with KF solution during GIC preparation resulted in no such surface layer. The formation of CaF@sub 2@-like layers on immersion was entirely unexpected on the basis of previous solution-based experiments and may explain differences in measured uptake kinetics. The use of these techniques has been extended to examine the inclusion of molecular active species (amprolium hydrochloride and chlorhexidine acetate) within the GIC matrix. Both species could be detected in GIC samples irrespective of whether they were included by mixing or by immersion in solution. However, relative peak intensities indicated that the binding of the active molecule is dependent on the method of inclusion. Significant applications in the study of the uptake and release mechanisms of active species such as antibacterial and antifungal agents are envisaged. @FootnoteText@ @footnote 1@ Hadley P, Billington RW, Pearson GJ. Biomaterials 1999;20:891-897.