Experimental Study Of Biocompatibility Of Osteoid Hydroxyapatite

Bone tissue defect occured in maxillofacial region resulting from tumor, inflammation and trauma is always a difficulty for orthopedic surgeons. Bone transplantation acting as a kind of prosthetic treatment is necessary. Autogenous iliac bone graft is a golden standard of bone transplantation.But it may result in major disadvantages and bad cosmetic effect in local complications. How to improve the effect of bone graft is becoming a focus in maxillofacial prosthesis. In recent years, the development of bong tissue-engineering provided a new pathway and opened up a wide prospect for maxillofacial prosthesis. Tissue-engineering is a science of investigation and develop new functional tissue in vivo by biomaterial acting as carrier of cell and growth factor, applying method of cell biology and engineering. Tissue-engineering technique is featured by cografting with a seed cell-scaffold compound to restore, retention and ameliorate tissue function. Its principle is forming tissue possessing normal constitution and function by utilizing biomaterial acting as carrier, taking along with a series of seed cells and implanting them in vivo. And the biocompatibility of bone engineering scaffolds becomes a key point which affects the result of tissue-engineering.Osteoid hydroxyapatite(OHA) is a new kind of scaffold material used in maxillofacial prosthesis and is constituted of HA and suitable compound tricalcium phosphate. Compound tricalcium phosphate with adding to Na⁺, Mg²⁺ and CO₃^2-and high rate of porosity is in theory esay to grow into with tissue and dissolve, and is benefit to a adhesiveness of cell.In order to further understand the biocompatibility of OHA and study itsactual feasibility acting as scaffold material in maxillofacial prosthesis, Cranii osteoblast is cultured in special culture medium adding to OHA and its changes in shape and physiological function are observed. The results are:1. Cells adhere and grow well aroud and in porosity of material, and its shape does not change nearly. Invert microscope and cell counting show that the amount of adhesive cell is more and cell proliferation increases in OHA culture medium than ordinary tricalcium phosphate. The finding suggests that OHA has better biocompatibility.2. The cytotoxicity in all groups of different concentration of OHA is 0 degree by MTT reduction assay. Cell proliferation significantly increases in the groups of 50% and 100%(P<0.05); ALP activity and total micro-protein in all groups of different concentration is almost not different from contrast in statistics (P>0.05).In result, OHA has no toxic effect on cranii osteoblast. Osteoblast cultured in OHA culture medium can adhere to material surface and grow into the porosity of material and proliferate, showing better functional activity compared with in common culture medium. These findings suggest that OHA has good biocompatibility and can be used as scaffold material in maxillofacial prosthesis.