| Summary: | 碩士 === 國立成功大學 === 材料科學及工程學系 === 104 === Summary
In nineteenth century, the calcium sulfate had been used in medical application to fill bone defect. Calcium sulfate has good biocompatibility in human body. When it is implanted in the human body , there will be not the phenomenon of hypercalcemia syndrome, complications, and even without any infection. But the drawback is that calcium sulfate degrades rapidly in vivo , in other words , it will soon be absorbed rapidly. In this study, calcium sulfate dehydrate will be mixed with diammonium hydrogen phosphate solution synthesize HA powder. Control the synthesis time, in order to get the different proportion powder with calcium sulfate and calcium phosphate. Expect by mixing the calcium phosphate powder to reduce the degradation rate. And then we can fabricate a calcium sulfate bone cement that has appropriate degradation rate, handleability, and injectability.
Key words: calcium sulfate cement, calcium phosphate cement
Introduction
In early stage, the bone defect was filled by autogenous bone graft or allografts. Most of the autogenous bone graft was got from iliac or ribs, but the disadvantage is that it will increase the risk of the surgery. Alloplasty do not have this problem ,so it is the tendency in the future.
Calcium phosphate and calcium sulfate are two typical such bioresorbable materials, calcium sulfate has become one of the most promising bone substitute materials today, because it has many advantage ,such as bioresorbable, , osteoconductivity and biocompatibility. But the disvantage of the calcium sulfate is that it has high rates of dissolution. High dissolution rate may not allow new bone cells to effectively grow into a bone cavity, so in this study will devote to investigate whether a calcium phosphate/calcium sulfate composite will lower the dissolution rate or not.
Materials and Methods
• The powders were made from the materials and chemicals listed in Table 3-1-1-1. And then use the powder to test compressive strength , weight loss , porosity , pH , working time , setting time , injectability , disintegrating , SEM and XRD to find an suitable synthesis arameter.
Result and Discussion
All powders with different soaking time have the good injectability. In weight loss test, the samples with pressure of 0.7Mpa have higher compressive strength then pressureless samples. The high concentration of setting solution (C2M) also has higher compressive strength then low concentration of setting solution (C1M) . In porosity test, no mater the different concentration setting solution, the porosity will not change, it will maintain 50%~60%. The pH value will increase with increasing immersing time. Compare the XRD analysis, the powder with longer soaking time has a higher intensity of calcium phosphate and lower intensity of calcium sulfate than the powder with shorter soaking time. Compare the SEM analysis, the powder with longer soaking time has more calcium phosphate granue than the powder with shorter soaking time. And the surface of ocylindrical will be smooth when adding the high concentration of setting solution (C2M).
Conclusion
(1) Compare the compressive strength and weight loss, when the concentration of setting liquid is C2M and the soaking time is t2, it will has the highest compressive strength and the lowest weight loss in day 14.
(2) The working time, pH value, injectability and dispersion do not have obviously different with different concentration setting liquid and different soaking time.
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