Effects of boron oxide on the structure, properties and bioactivities of bioactive glasses: A review

Borate and boron oxide containing bioactive glasses have drawn attention because of their unique properties and potential biomedical applications. In this paper, we review recent advances in understanding of boron oxide addition on the structures and properties of bioactive glasses from both experimental and simulation studies. After reviewing the synthesis, characterization and applications of these novel bioactive glasses, recent developments of simulation methodologies including the interatomic potentials to model boron oxide containing bioactive glasses are reviewed. Effect of boron oxide to silica substitution on a range of properties such as density, glass transition temperature, coefficient of thermal expansion, diffusion and mechanical properties, as well as crystallization behavior, both from our own studies and those from literature, are summarized. Furthermore, influence of boron oxide on in vitro bioactivity in several bioactive glass series are reviewed and discussed, emphasizing the importance of in vitro testing conditions on the bioactivity evaluation. Lastly, an outlook of future directions of the field has been provided.