Bioactive glasses - When glass science and technology meet regenerative medicine

Over the millennia, men have continuously potentiated their abilities through developing and applying new materials and technologies. A number of metallic, ceramic and polymeric implants have been experimented as "spare parts" to restore lost functions or organs in the body. Till the 1960s, the selection of potentially suitable prosthetic materials was based on the criterion of maximum biological and biochemical inertness in contact with body fluids. Fifty years ago, the invention of the first bioactive glass, which was able to create a strong bond with living bone, radically changed this concept and paved the way for the advent of the modern era of biomaterials science. Since then, a number of bioactive glass-based products, such as small solid blocks, fine particles, granules, porous scaffolds and injectable putties, have been implanted in millions of patients primarily to repair bone and dental defects. Over the last decade, bioactive glasses have also shown promise in highly fascinating, emerging applications that involve angiogenesis (e.g. wound healing), interfacial hard-soft tissue engineering and controlled drug delivery. This review offers the reader a "guided tour" in the field of bioactive glass science and technology, also highlighting the future challenges to be met by materials scientists, bioengineers and clinicians to further exploit the benefits associated to these ever-surprising materials, which were unthinkable when research began.