Bone graft substitutes are commonly used to replace and regenerate bone lost due to trauma, infection, disease, or for stability around implanted devices [1]. Current generation biomaterials are designed to stimulate specific cellular responses at the molecular level. This generation of biomaterials is both bioactive and degradable and might be osteoconductive or osteoinductive [2].

Bioactivity refers to any interaction or effect that materials have on cells to activate specific responses [3, 4]. Such a promising biomaterial is bioactive glass, an osteostimulative material that is currently used as bone graft substitute and in the treatment of osteomyelitis. Osteostimulation refers to osteoblast cell recruitment and/or differentiation and osteoblast activation to produce new bone in a bony environment [5].

Osteostimulation should not be confused with osteoinduction, which is the ability ofmaterials to recruit stem cells to differentiate into bone forming cells and form ectopic bone. Also it should not be confused with osteoconduction, which is the possibility for bone to grow along the material, in other words only providing a scaffold for bone formation [6]. Bioactive glass is an osteostimulativematerial; thus it is osteoconductive and serves as a scaffold for bone formation in vivo , but it is not fully osteoinductive since it will only form new orthotopic bone (whereas osteoinductive materials are able to form ectopic bone).