A new hydrolytic route to an experimental glass for use in bioactive glass-ionomer cement

Abstract

Routes to glass-ionomer cements (GICs) have been previously explored through traditional silica-precursors, however, economic routes have not been fully reported. Herein, glass-ionomer powder was prepared through a new hydrolytic- and economic-route. The mechanical properties and bioactivity of the prepared GIC relative to a commercial GIC were investigated. Silica was derived from sodium metasilicate rather than conventional alkoxysilanes. Sodium metasilicate was hydrolysed with hydrochloric acid to form a gel, which was washed until residual impurity was removed, then aged and dried to obtain silica. Silica was thereafter dissolved in citric acid to form a complex used for encapsulating other precursors. Afterwards, a burnout procedure was performed on the silica-citric acid-precursor moiety to obtain glass-ionomer powder. Cements were formed from the as-prepared powder and commercial powder using a similar polymer solution. The cements were subjected to mechanical testing and bioactivity tests in simulated body fluid (SBF). The samples were characterised using scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction and Fourier transform infrared spectroscopy. The experimental GIC exhibited compressive, flexural strength and microhardness of 103.65 (± 4.53) MPa, 17.41 (± 1.69) MPa and 64.10 (± 3.84) KHN, respectively; while those for the commercial GIC were 118.86 (± 1.67) MPa, 21.63 (± 2.36) MPa and 72.45 (± 3.30) KHN, respectively. The obtained GIC upon immersion in SBF over a 28-day period compared with commercial GIC by showing good level of stability while nucleating a layer of apatite-like deposits on its surface. GIC obtained via this new hydrolytic method could serve as a candidate dental restorative material.

Keywords

• Bioactivity
• Glass-ionomer cement
• Hydrolytic route
• Mechanical properties
• Silica
• Sodium metasilicate