Mechanical Property And Osteogenic Induction Ability Of Calcium Citrate Bone Cement

Objective:1.Prepare calcium citrate bone cement with ideal compressive strength. 2.Make research on physical and chemical properties of calcium citrate bone cement. 3. Evaluate the biocompatibility and osteoinductivity of the bone cement.Methods:1.C itric acid powder and sodium citrate powder were mixed according to a certain proportion and were dissolved in distilled water to make citric acid / sodium citrate solution.2.To make calcium citrate bone cement by mixing citric acid / sodium citrate solution and α-tricalcium phosphatepowder in different liquid-powder ratio and test their compressive strength respectively to determine the best liquid-powder ratio in which the compressive strength reached maximum.3.Four groups of bone cements with different cement liquid were synthesized. Their powder was α-tricalcium phosphate(α-TCP),their cement liquid was deionized water, citric acid solution, sodium citrate solution, citric acid /sodium citrate solution. After 72 h, the hardened bone cements samples were obtained and their compressive strength were tested.4.Compare the anti- washout property of bone cements in four groups.5. The initial and final setting time of bone cements in four groups was measured expectively.6.SEM was used to observe the microstructure of the bone cement in four groups.7.The phase analysis of bone cements in different groups was performed by XRD. 8.The typical chemical group of bone cements in four groups was analysed by FTIR. 9.The biocompatibility of bone cements in vitro was assessed by CCK-8 after MC3T3-E1 was cultured in the extracts of the bone cements.10.The ostectomized cavities on the femur of Wistar rats were filled with α-TCP、α-TCP/CA/TC respectively. The bone tissues were observed by Micro-CT at 2, 4, 6, 8 weeks.Results: 1.When the liquid-powder ratio was 0.33ml/g, the compressive strength of bone cements reached the maximum, 53 MPa on average.2.The compressive strength of bone cements whose cement liquid was deionized water, citric acid solution, sodium citrate solution, citric acid /sodium citrate solution respectively was 24±0.6MPa、39±2.9MPa、15±5.6MPa、55±4.5MPa accordingly.3.The anti-washout property of α-TCP/C A、α-TCP/CA/TC was better than α-TCP、α-TCP/TC.4.Citric acid could obviously shorten the initial and final setting time of bone cements.5.The SEM showed the surface of α-TCP/CA/TC was more compact with smaller voids than other groups. Needle-like crystals were formed on the surface of α-TCP/CA/TC.6.The XRD spectrum of α-TCP、α-TCP/CA、α-TCP/TC、α-TCP/CA/TC clearly indicated that in α-TCP/CA/TC group the component of bone cement had partly changed to hydroxyapatite(HA).7. FTIR showed that HA existed in α-TCP/CA/TC group after incubating for 72 h.8.The CCK-8 assay indicated that α-TCP/TC and α-TCP/CA/TC groups had no obvious effect on the cell viability compared with the negative control.9.Micro-CT result showed that ostectomized cavities on the femur in α-TCP/CA/TC groupand blank group were almost filled with regenerated bone. Compared with α-TCP group, α-TCP/CA/TCgroup showed better oeteoinductivity.Conclusion: 1.When the liquid-powder ratio was 0.33ml/g, the compressive strength of bone cements reached the maximum, 53 MPa on average.2.The compressive strength of bone cements in two groups in which its cement liquid included citric acid was higher obviously than another two groups, besides, the compressive strength of bone cement whose cement liquid included both citric acid and sodium citrate was the highest one in the four groups.3.C itric acid could improve the anti- washout property of bone cements. Cement liquidincluding both citric acid and sodium citrate could lead to proper initial and final setting time of bone cements.4. The vitro and vivo assay indicated that α-TCP/CA/TCbone cement had no toxicity and could promote cell proliferation as well as good oesteoinductivity.