The Preparation Of α-calcium Sulphate Hemihydrate And Sustained Release Of CSH-baced Cement

With the increase requirement of clinical grafting material, the study of artificial bone is accelerating. Calcium sulphate dihydrate (CSD) is a promising inorganic bone replacement material with excellent biocompatibility and degradation in vivo and short-setting time, and it has been well recognized by researchers and surgeons.In this research, the effects of technical parameters, such as, temperature, time and additives, on crystalline forms and morphology ofα-CSH crystal were investigated. CSD-based cement can been manufactured into the desired shapes for clinical applications and setting in certain periods in situ. Pores was obvious after setting. It can be the carrier of drug to fill bone default, avoid infection and speed osteal cicatrization. Furthermore, the degradation makes the compressive strength and security better. But the rapid setting time confined it widely use in orthopedics and this can be improved by addingα-tricalcium phosphate(α-TCP) to compose CSH/TCP binary controllable-degradation cement.Getting the optimal process conditions of prepareα-CSH, that is: Heating the raw material 3-5hours at 140℃in autoclave by the gas-heating and drying at 110℃. The product has well shape and growth along B-axis. The additive is propitious to crystal forming and optimization. Analysis to structural characteristic and physical properties , contrast the crystal structure of CSH to PDF by XRD offer the message to built crystal identification. The setting of CSH/TCP binary cement finished within 48hours and have no interact with each other, L/P ratio and mass percent affect the setting. The netlike structure formed after setting, fibers of hydroxyapatite enhanced strength of binary cement through fiber-reinforce mechanism, which provide the theoretic foundation to better strength and the instructional foundation to osteogenesis or drug carrier for the 5-20μm pores structure. Ciprofloxacin has a wide antibacterial spectrum with good sensitivity for both Gram positive and negative germs. It could be the first choice in anti - post - operative infections in orthopedic clinics and have no hurt to the strength and setting of the binary cement. Only 20% ciprofloxacin was released from CSH-TCP cement in 7 days in vitro. At initial stage (less than 100 hours), the release of ciprofloxacin from CSH-TCP cement was diffusion control, and at subsequent stage the release was matrix dissolution & diffusion control.