IADR Abstract Archives
Novel Strontium-substituted Fluorapatite Glass-ceramics for Remineralising Glass Ionomer Cements
Objectives: Although fluorapatite (FAp) additives in glass ionomer cement (GIC) may act as nuclei for the remineralisation of tooth, they affect the aesthetics of the material. Upon controlled heat-treatment GIC glasses which contain strontium as a radiopacifier can nano-crystallise to produce glass-ceramics (GC) with FAp within the glass matrix. Such glasses will be beneficial for enhancing the remineralising potential of GICs without affecting the aesthetics. The aim of this study is to develop novel strontium-substituted GCs for use in GICs.
Methods: A series of glasses of varying strontium substitution for calcium, based on the SiO2-Al2O3-P2O5-CaO/SrO-CaF2 system was produced by the melt-quench route. For heat-induced apatite crystallisation all glasses were subjected to a heat-treatment regime at the following temperatures Tg, Tg+50°C, Tg+100°C and Tg+150°C for 1 hour. Glasses were then analysed by HT-DSC, multinuclear MAS-NMR, XRD, ATR-FTIR and SEM before and after heat-treatment to assess apatite crystallisation.
Results: HT-DSC data suggests that increasing strontium content results in reduced volume crystallisation and a linear reduction in Tg. 31P MAS-NMR analysis of the glasses showed presence of apatite after heat treatment. 19F MAS-NMR analysis confirmed this be in the form of fluorapatite. Increasing heat-treatment temperature resulted in increased apatite crystallisation. SEM of heat-treated glasses showed needle-like fluorapatite crystals within the amorphous glass matrix.
Conclusions: Fluorapatite containing glasses have been successfully developed for use in GICs. Increasing strontium content in the above systems was found to have a profound effect on the crystallisation behaviour of the glasses. Crystalline phase in the developed apatite containing glasses was identified to be a mixed strontium/calcium fluorapatite phase.
Methods: A series of glasses of varying strontium substitution for calcium, based on the SiO2-Al2O3-P2O5-CaO/SrO-CaF2 system was produced by the melt-quench route. For heat-induced apatite crystallisation all glasses were subjected to a heat-treatment regime at the following temperatures Tg, Tg+50°C, Tg+100°C and Tg+150°C for 1 hour. Glasses were then analysed by HT-DSC, multinuclear MAS-NMR, XRD, ATR-FTIR and SEM before and after heat-treatment to assess apatite crystallisation.
Results: HT-DSC data suggests that increasing strontium content results in reduced volume crystallisation and a linear reduction in Tg. 31P MAS-NMR analysis of the glasses showed presence of apatite after heat treatment. 19F MAS-NMR analysis confirmed this be in the form of fluorapatite. Increasing heat-treatment temperature resulted in increased apatite crystallisation. SEM of heat-treated glasses showed needle-like fluorapatite crystals within the amorphous glass matrix.
Conclusions: Fluorapatite containing glasses have been successfully developed for use in GICs. Increasing strontium content in the above systems was found to have a profound effect on the crystallisation behaviour of the glasses. Crystalline phase in the developed apatite containing glasses was identified to be a mixed strontium/calcium fluorapatite phase.
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