ABSTRACT
BACKGROUND:In view of the unavoidable problems of autogenous and al ogenous bone grafts, it is an urgent need to develop biodegradable bone substitute materials, among which is calcium phosphate material that has become a hot spot in the domestic and foreign research. OBJECTIVE:To develop a biodegradable calcium phosphate material for bone repair based on tetracalcium phosphate (TTCP). METHODS:The biodegradable calcium phosphate cement made from TTCP, dicalcium phosphate anhydrous and different constituents of curing liquids was prepared under room temperature (about 25 ℃). The effects of solid components, liquid components as well as calcinations and drying temperature on the physical and biological performances were detected through X-ray diffraction test, hardness test, decay in a simulated body fluid, hemolysis and cytotoxicity tests, respectively, to select the bone repair material with excel ent performances. RESULTS AND CONCLUSION:When the calcination temperature was lower than 1300 ℃, TTCP was rarely available;only close to 1400 ℃, the relatively pure TTCP was gained. A large number of pure TTCP were gained by rapid cooling because of avoidance of the moisture impact, but slow cooling made the main products to be hydroxyapatite, suggesting that rapid cooling is essential to obtain pure TTCP. With the increase of the proportion of citric acid solution in the liquid phase, the pH values and the hemolysis rate in the bone cement soak solution were increased gradually, illustrating that citric acid solution is easy to induce hemolysis. In vitro cel experiments showed that the hemolysis rate of bone cement with a solution of 2:1 NH4/Na ratio was the lowest, and the biocompatibility was the best, which was the most favorable to cel growth. Cements was made of calcined powders sieved at 1400 ℃ and showed the shortest initial setting time, least effect on pH values, lowest disintegration rate and hemolysis rate, and slightest inhibition effect on the cel proliferation, indicating that the bone cements made of sieved powder after 1400 ℃ calcination is more suitable for clinical application.