RESUMO
BACKGROUND:Biphasic calcium phosphates, consisting of hydroxyapatite and beta-tricalcium phosphate, have been extensively applied as bone graft substitutes due to their similarity with the mineral portion of nature bone. They have been proved to have excellent biocompatibility, bioactivity and osteoconductivity. In recent years, many studies have il ustrated biphasic calcium phosphates perform osteoinductivity both in vitro and in vivo, which is expected to become a good choice for bone graft substitutes. However, the critical factors triggering the osteoinduction process and mechanism of this phenomenon are stil indistinct. OBJECTIVE:To review the influencing factors and mechanism related to the osteoinductivity of biphasic calcium phosphates. METHODS:The Ovid Medline database and PubMed database (1985-01/2013-01) were used to search the related articles about the osteoinductive property of biphasic calcium phosphates. The key words were“bone graft substitutes, biphasic calcium phosphates, osteoinduction”. Articles concerning the osteoinductive property of biphasic calcium phosphates were included. The articles that published recently or in the high-impact journals were preferred, and articles with repetitive contents were ruled out. Then 34 articles were suitable for further analysis. RESULTS AND CONCLUSION:The chemical composition of biphasic calcium phosphates influences the rate of degradation/resorption as wel as bioactivity, which in turn has an influence on the osteoinductivity;the physical properties also play important roles in osteoinductivity by affecting the absorption of bone morphogenetic proteins, vascularization, tissue invasion, microenvironment, and more importantly, triggering the undifferentiated stem cells into osteogenic lineage. What’s more, the species of animals, the implantation-site and the implant size are also critical for osteoinduction. Therefore, through the further study on the influencing factors and mechanism of osteoinduction, biphasic calcium phosphates with stable osteoinductivity, as a promising bone graft substitute, could be synthesized for clinical applications.