An x-ray diffraction study of the structure of Bioglass and its sol-gel analogue as a function of composition

The FDA approved BioGlass (R) product is one of very few bone regenerative materials actually in clinical use, having been used in similar to 650,000 cases already. The BioGlass family are, in essence, melt quenched calcium silicate glasses with additional alkali and aklaline earth modifiers, of general compositions CaO-Na2O-P2O5-SiO2. We report herein the first high energy x-ray diffraction data on this important material in the hope of providing a more direct experimental insight into the glass structure. The structure of three compositions of melt quenched bioactive glass (45S5 (Bioglass), 55S5, and 60S5) and one composition of an analogous (i.e. it has similar structure and properties but has different elemental composition) sol-gel bioactive glass (77S5) have been investigated. There are significant changes occurring as a function of composition and of preparation method, but these may all be ascribed to the relative concentrations of the sample's constituent elements (e.g. the absence of Na as a network modifier in the sol-gel sample and the counter effect of the presence of-OH, and the overall variation of the Si-associated features as the relative SiO2 fraction alters). Overall, the underlying network structure is seen to be comparable in all samples.