Sodium is not essential for high bioactivity of glasses

Abstract

This study aims to demonstrate that excellent bioactivity of glass can be achieved without the presence of an alkali metal component in glass composition.In vitro bioactivity of two sodium-free glasses based on the quaternary system SiO 2 -P 2 O 5 -CaOCaF 2 with 0 and 4.5 mol% CaF 2 content was investigated and compared with the sodium containing glasses with equivalent amount of CaF 2 . The formation of apatite after immersion in Tris buffer was followed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), 31 P and 19 F solid state MAS-NMR. The dissolution study was completed by ion release measurements in Tris buffer.The results show that sodium free bioactive glasses formed apatite at 3 hours of immersion in Tris buffer, which is as fast as the corresponding sodium containing composition. This signifies that sodium is not an essential component in bioactive glasses and it is possible to make equally degradable bioactive glasses with or without sodium. The results presented here also emphasize the central role of the glass compositions design which is based on understanding of structural role of components and/or predicting the network connectivity of glasses.

A New Customized Bioactive Glass Filler to Functionalize Resin Composites: Acid-Neutralizing Capability, Degree of Conversion, and Apatite Precipitation

“…However, in this study, reducing the amount of Na 2 O from 24.5 wt% to 10.5 wt% was accompanied by adjusting the relative ratios of other elements (Table 1) to maintain network connectivity at the level of BG 45S5. These compositional modifications helped to maintain optimal reactivity of the experimental BG [34].…”

Bioactive Glass Applications in Dentistry

“…Na has been considered an essential component for the bioactivity, as it effectively disrupts the glass network. However, sodium-free BAG has been fabricated and shown to possess equal dissolution and bioactivity as traditional sodium contained BAG, thus discrediting Na as an essential component [15]. Further, it has been established that the rate of degradation and apatite formation is highly influenced by the connectivity of the glass silica network and the amount of phosphate.…”

Structural and thermal behavior of 45S5 Bioglass®‐based compositions containing alumina and strontium

“…Considering the presence of two subnetwork and so two T g , from the DSC curves was possible to observe that all samples did not present substantial changes in T g —corresponded to the silicate phase (majority phase due to its concentration)—occurring between 520°C (BioH) and 539°C (BioSr). In contrast, a significant displacement of the crystallization peak was observed in samples containing alumina (BioAl and BioAlSr) besides evidencing the presence of a second T g2 —event already observed in bioactive glasses containing more than one alkali—suggesting the impact of both alumina and strontium mostly in the orthophosphate subnetwork. The TEC obtained at 500°C from dilatometry varied from 14.89 × 10 −6 (BioH) to 16.90 × 10 −6 (BioAl) and were very similar for BioSr and BioAlSr corresponding to 15.64 and 15.69 × 10 −6 respectively.…”