Bioactive glass-based composites for the production of dense sintered bodies and porous scaffolds

Recently several attempts have been made to combine calcium phosphates, such as β-tricalcium phosphate (β-TCP) and, most of all, hydroxyapatite (HA), with bioactive glasses of different composition, in order to develop composites with improved biological and mechanical performance. Unfortunately, the production of such systems usually implies a high-temperature treatment (up to 1300 °C), which may result in several drawbacks, including crystallization of the original glass, decomposition of the calcium phosphate phase and/or reactions between the constituent phases, with non-trivial consequences in terms of microstructure, bioactivity and mechanical properties of the final samples. In the present contribution, novel binary composites have been obtained by sintering a bioactive glass, characterized by a low tendency to crystallize, with the addition of HA or β-TCP as the second phase. In particular, the composites have been treated at a relatively low temperature (818 °C and 830 °C, depending on the sample), thus preserving the amorphous structure of the glass and minimizing the interaction between the constituent phases. The effects of the glass composition, calcium phosphate nature and processing conditions on the composite microstructure, mechanical properties and in vitro bioactivity have been systematically discussed. To conclude, a feasibility study to obtain scaffolds for bone tissue regeneration has been proposed.