Bioactivity modulation of Bioglass® powder by thermal treatment

A discussion of the effects of Bioglass® powder crystallisation on the in vitro bioactivity in simulated body fluid (SBF) is presented.Starting from Bioglass® powder, different glass–ceramics were obtained by thermal treatments between 580 °C and 800 °C, with variable crystallisation content (from 10 to 92 wt%). All samples (glass and glass–ceramics) showed apatite formation at their surface when immersed in SBF. In case of the glass and the samples with lowest crystallinity, the first step of apatite formation involved a homogenous dissolution followed by an amorphous calcium phosphate (CaP) layer precipitation. For the samples with a high crystallisation content, heterogeneous dissolution occurred. For the first time, the Stevels number of the amorphous phase is used to explain the possible dissolution of the crystalline phase present in materials with a similar chemical composition of the Bioglass®. All samples presented at 21 days of immersion in SBF B-type hydroxycarbonate apatite crystals.