Bioactivity and cytotoxicity of glass and glass–ceramics based on the 3CaO·P2O5–SiO2–MgO system

Abstract

The mechanical strength of bioactive glasses can be improved by controlled crystallization, turning its use as bulk bone implants viable. However, crystallization may affect the bioactivity of the material. The aim of this study was to develop glass-ceramics of the nominal composition (wt%) 52.75(3CaO·P₂O₅)-30SiO₂-17.25MgO, with different crystallized fractions and to evaluate their in vitro cytotoxicity and bioactivity. Specimens were heat-treated at 700, 775 and 975 °C, for 4 h. The major crystalline phase identified was whitlockite, an Mg-substituted tricalcium phosphate. The evaluation of the cytotoxicity was carried out by the neutral red uptake methodology. Ionic exchanges with the simulated body fluid SBF-K9 acellular solution during the in vitro bioactivity tests highlight the differences in terms of chemical reactivity between the glass and the glass-ceramics. The effect of crystallinity on the rates of hydroxycarbonate apatite (HCA) formation was followed by Fourier transformed infrared spectroscopy. Although all glass-ceramics can be considered bioactive, the glass-ceramic heat-treated at 775 °C (V775-4) presented the most interesting result, because the onset for HCA formation is at about 24 h and after 7 days the HCA layer dominates completely the spectrum. This occurs probably due to the presence of the whitlockite phase (3(Ca,Mg)O·P₂O₅). All samples were considered not cytotoxic.

In vitro study of dentin hypersensitivity treated by whitlockite glass-ceramics

“…The results found in this study met the initial expectations based on the literature (Wang et al, 2011) (Daguano et al, 2013) (Mundstock et al, 2012). Daguano et al showed that the bioactive glass-ceramic used on this project, V775-4 from the 3CaO.P 2 O 5 -SiO 2 -MgO system, possesses whitlockite as its main crystalline phase, which favors the biocompability of the material, and is consistent with the results achieved in that study (Daguano et al, 2013).…”

“…Daguano et al showed that the bioactive glass-ceramic used on this project, V775-4 from the 3CaO.P 2 O 5 -SiO 2 -MgO system, possesses whitlockite as its main crystalline phase, which favors the biocompability of the material, and is consistent with the results achieved in that study (Daguano et al, 2013). This same work shows that the bioactive glass-ceramic V775-4 takes very little time to form a layer of hydroxyapatite, approximately of one day, which is also due to the presence of whitlockite.…”

“…Daguano et al (Daguano et al, 2013) showed that the bioactive glass-ceramic used in this study, V775-4, has significant similarities with Bioglass® 45S5 in terms of surface reactivity. In the present study, the similarity XXXX was confirmed by the proximity of the values encountered on the area of the bands of phosphate of the groups treated with bioactive glassceramic from the 3CaO.P 2 O 5 -SiO 2 -MgO system and treated with Bioglass® 45S5.…”

“…The bioactive glass from the 3CaO.P 2 O 5 -SiO 2 -MgO system also showed a considerable band of phosphate, which confirms the presence of hydroxyapatite. It is important to point out that the time needed by the bioactive glass to form the hydroxyapatite is five times higher than the time needed by the bioactive glass-ceramic, as shown by in vitro bioactivity tests conducted by Daguano et al (Daguano et al, 2013). The importance of the presence of the phosphate is due to its similarity with the bone and dentin mineral matrix, which favors the biocompability of the material.…”

“…Although it is already established that bioactive glasses and glass-ceramics from the 3CaO.P 2 O 5 -SiO 2 -MgO system have bioactive properties when exposed to simulated body fluids, and that the presence of whitlockite as crystalline phase in the bioactive glass-ceramic from that system contributes for increasing its biocompability and mechanical properties (Daguano et al, 2013), there is still the need for a quantitative analysis that determines how successful was the connection between the biomaterial and the dentin tissue. In this context, this study performed a semi-quantitative analysis of the mineral variations on the dentin surface when treated with bioactive glass and glass-ceramic from the 3CaO.P 2 O 5 -SiO 2 -MgO system.…”