Predicting physical and chemical properties of bioactive glasses from chemical composition. Part 4: Tailoring compositions with desired properties

Models for calculating the physical and chemical properties of bioactive glasses were used to formulate novel compositions with pre-specified properties. Compositions allowing glass to be worked into various product forms and with different degrees of in vitro bioactivity were tested. The two physical properties measured, viscosity and divetrification characteristics, had values very similar to those anticipated based on the models. Vie in vitro bioactivity was assessed based on the propensity to form a calcium phosphate surface layer on the glasses in simulated body fluid, as well as by changes in the pH and concentration of ions in simulated body fluid during immersion of the glasses. The glasses were divided into different bioactivity groups depending on the relative change of the in vitro properties. The in vitro tests showed that the measured in vitro bioactivity properties of novel glasses once again were very similar to those anticipated based on the models. Thus, the models offer a method for tailoring glass compositions to have desired in vitro bioactivity as well as favourable properties for manufacturing desired product forms.