The role of Sr2+ on the structure and reactivity of SrO–CaO–ZnO–SiO2 ionomer glasses

Abstract

The suitability of Glass Polyalkenoate Cements (GPCs) for use in orthopaedics is retarded by the presence in the glass phase of aluminium, a neurotoxin. Unfortunately, the aluminium ion plays an integral role in the setting process of GPCs and its absence is likely to hinder cement formation. However, the authors have previously shown that aluminium free GPCs may be formulated based on calcium zinc silicate glasses and these novel materials exhibit significant potential as hard tissue biomaterials. To further improve their potential, and given that Strontium (Sr) based drugs have had success in the treatment of osteoporosis, the authors have substituted Calcium (Ca) with Sr in the glass phase of a series of aluminium free GPCs. However to date little data exists on the effect SrO has on the structure and reactivity of SrO-CaO-ZnO-SiO(2) glasses. The objective of this work was to characterise the effect of the Ca/Sr substitution on the structure of such glasses, and evaluate the subsequent reactivity of these glasses with an aqueous solution of Polyacrylic acid (PAA). To this end (29)Si MAS-NMR, differential scanning calorimetry (DSC), X-ray diffraction, and network connectivity calculations, were used to characterize the structure of four strontium calcium zinc silicate glasses. Following glass characterization, GPCs were produced from each glass using a 40 wt% solution of PAA (powder:liquid = 2:1.5). The working times and setting times of the GPCs were recorded as per International standard ISO9917. The results acquired as part of this research indicate that the substitution of Ca for Sr in the glasses examined did not appear to significantly affect the structure of the glasses investigated. However it was noted that increasing the amount of Ca substituted for Sr did result in a concomitant increase in setting times, a feature that may be attributable to the higher basicity of SrO over CaO.

Glass-ionomer Cement SiO2, Al2O3, Na2O, CaO, P2O5, F- Containing Alternative Additive of Zn and Sr Prepared by Sol–gel method

“…So, the addition of ZnO has a smaller disrupting effect on the structure and hence it will strengthen the network (31) . This result was in agreement with that of Boyd et al (32) who worked on a SrO-CaO-ZnO-SiO 2 glass ionomer composition and that of Abou Neel et al (33) who worked on Srdoped phosphate glasses.…”

Preparation, Physicochemical Characterization, and Bioactivity Evaluation of Strontium-Containing Glass Ionomer Cement

“…There are, however, limited studies on strontium-containing bioactive glass bone substitutes. The role of Sr on the structure and reactivity of dental ionomer glasses has been reported by Boyd et al [18]. Abou Neel et al [19] reported some structural and physical characteristics of melt-derived phosphate glasses based on Na 2 O-CaO-SrO-P 2 O 5 system.…”

Investigating the influence of Na+ and Sr2+ on the structure and solubility of SiO2–TiO2–CaO–Na2O/SrO bioactive glass

“…, Sr 2? ) act predominantly as a network modifier within a glass structure [3,14], and this study aims to use complementary characterization techniques such as high resolution XPS, magic-angle spinning nuclear magnetic resonance (MAS-NMR) and Raman spectroscopy to investigate any structural differences within the glass as a result of Na ? and Sr 2?…”