Influence of physico-chemical properties, macro- and microstructure on osteoinductive potential of calcium-phosphate ceramics

Osteoinduction by biomaterials that initially do not contain bone morphogenetic proteins and other growth factors has been shown to be a real phenomenon by many investigators in the past two decades. Although it is well-known that a material needs to meet very specific requirements in terms of physico-chemical and structural properties in order to be osteoinductive, the underlying mechanism of osteoinduction is not fully unraveled yet. In the present study we investigated parameters which are of importance for the osteoinductive potential of biomaterials by comparing four biphasic calcium-phosphate and a carbonated apatite ceramic. The results showed that the presence of micropores, by which the specific surface area of a material is increased, is essential for the material's osteoinductivity. However, if the surface area is too high, or material is too resorbable because of its chemical composition, the implant might degrade and lose its shape. In that case, ectopic bone formation does not occur, as a relatively stable surface is needed to facilitate new bone growth.