Bioactive Glasses for Bone Regeneration

Bioactive glasses (BGs) are a new material for bone regeneration because they behave as a material that can bond with bone tissues to elicit a cell response. BGs were first developed by Hench in the 1960s and are silicate-based materials that have been extensively utilized for orthopedic and dental applications, due to their osteoconductive and osteoinductive properties. They achieve their bioactivity mainly through the release of ionic dissolution products (e.g., calcium, phosphate, and silicon) which precipitate a hydroxyapatite-like layer on the surfaces, supporting bone integration. These ionic dissolution products can also facilitate osteoblast formation and differentiation and, therefore, new bone formation. There have also been recent developments of BG compositions which increasingly include borate- or phosphate-based BGs that have increased degradation rates and/or improved biological interaction. Additionally, the development of nanostructured and mesoporous BGs increases bioactivity by increasing surface area or modifying ionic release. BGs are generally incorporated into polymers or ceramics and often demonstrate composites for desired mechanical properties that are more appropriate for load-bearing applications. Additional value of BGs has come from the development of therapeutic ions (e.g., strontium, copper, silver) that can be incorporated for antibacterial, angiogenic, or osteogenic action, interactions. However, the brittleness of the BGs, the degradation time of some formulations, or low mechanical strength may need further investigation for composite formulation, or 3D-printed scaffolds.