Bioactive glass is a group of glasses which has a compositional range that allows the formation of hydroxyapatite (HA) as a surface layer when exposed to an aqueous phosphate containing solution such as simulated body fluid. The HA layer that forms in an aqueous phosphate containing solution plays a significant role in forming a strong bond with natural bone.
Bioactive glass has an established history of bone bonding that occurs as a result of a rapid sequence of reactions on its surface when implanted into living tissues. When hydrated, a layer of silica gel forms on the surface of the bioactive glass. The adhesion of amorphous calcium, phosphate, and carbonate ions to the silica surface leads to an eventual crystallization of a bone-like hydroxyapatite (HA) as early as 24 hours.