Fluoride has often been incorporated into many glasses used in dentistry, for example, glass ionomer cements, apatite based glass-ceramics and more recently fluoride containing bioactive glasses. However, chloride containing glasses have rarely been investigated. The objective of this project is to investigate incorporation of chloride into sodium free bioactive glasses.
Method:
Sodium free glasses with varying amounts of fluoride and chloride were synthesised by a melt-quench route and characterised using X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR). Glass powders were heat treated for the crystallisation study. Glass bioactivity was investigated by the immersion of glass powders in Tris buffer solution. The apatite formation was evaluated by XRD, FTIR and Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR). The ion release and glass degradation were quantified by Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES).
Result:
The results show that glasses with high fluoride (>9.3 mol%) content are partially crystallised into fluorapatite, however, CaF2 was found in 25.5 mol% CaF2 containing glass. Similarly, partial crystallisation of chlorapatite has been observed in the chloride containing glasses. Both glass series showed high bioactivity, the glasses degraded primarily within the first hour of immersion in Tris buffer and formed apatite within 3 hours. Fluorapatite and chlorapatite formed in the heat treated glasses.
Conclusion:
The presence of CaF2 / CaCl2 in sodium free bioactive glasses is beneficial for the fluorapatite/ chlorapatite formation. These highly bioactive halide glasses can be used for dental applications.