| Background:The defects in maxilla and mandible are common postnatal deformities. Usually large in area and complicated in structure, they often occur in postoperation of oral and maxillofacial neoplasm and trauma. Current restoration methods of autografting bone, allografting bone, xenografting bone and replacement of artificial materials all have their respective demerits. Objective:This study aims to conduct an effective compound between eucommia ulmoides extracts and calcium phosphate cement (CPC), producing a compound medium whose shapes can be modeled in advance. An analytical test has thus been made concerning its physical functions and activated responses in vivo and vitro in an effort to evaluate the feasibility of using CPC and eucommia ulmoides extracts compound in restoring bone defects in maxilla and mandible. Method: 1. The making of compound materials: Hydroxyapatite (HAP)/ β -tricalciumphosphate(p—TCP) is firstly obtained by way of adding (NHO2HPO4 (AP) into bull bones that have been burned twice. Then, Eucommia Ulmoides aqueous extracts are extracted by HPLC. The two things are compounded effectively for a physical analysis through measurement of setting time, compressive strength, solubility in water, PH value, porosity rate and through testing scanning electron microscope (SEM), X ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR).2. The research on biological activeness in vitro: The compound blocks respectively containing 0, 0.152, 0.304, 0.608mg/ml of eucommia ulmoides extracts are cultured together with osteoblastic cells (MC3T3—El) for 48 hours. In the meantime, the cell growth is tested by radioisotope 3H-TdR assay, the growth, proliferation and adhesion of osteoblastic cells on the surface and around the compound materials are observed by invert microscope and scanning electron microscope. The evaluation of cell compatibility in compound materials and the most appropriate density between eucommia ulmoides extracts and CPC in animal's tests can thus be made.3. The research of biological activeness in vivo: According to the experiment results of biological activeness in vitro, the most appropriate density between eucommia ulmoides extracts and CPC is determined. The CPC is then compounded with CPC/ eucommia ulmoides extracts into artificial bones. Rabbit skull models with three 9-millemeter bone defects are made. They are planted with artificial compound bones of CPC/ eucommia ulmoides extracts, pure CPC artificial bones, and vacuity as control, respectively. There are nine rabbits altogether. After four, eight and twelve months respectively, three rabbits are killed each time. Their specimens are made. The tissue compatibility and biological activeness are examined with the help of digital x-ray, histological observation and scanning electron microscope (SEM).Results:1. The CPC used in this study is tested by XRD to be biphasic crystalline structures of HAP and pTCP. The setting time of the compound is about 8 to 9 minutes, which conforms to clinical requirements. The compound of eucommia ulmoides extracts with certain density does not affect the setting time and compression strength. The compression strength is around 19Mpa, quite suitable for the restoration of bone defects that do not support much weight. The dissolving degree of CPC in water is 2.34%, with PH value in water between 6.8-7.5, which is suitable for the cultivation requirements of osteoblastic cells. The porosity is 31.3%, with the size of the pores at 5-100um. The XRD AND FTIR analysis finds that eucommia ulmoides extracts with certain density do not influence the physical function of CPC. Eucommia ulmoides extracts exist in CPC materials without any predetermined shapes.2. The compound of CPC/ eucommia ulmoides extracts is cultured together with the osteoblastic cells of MC3T3—El. The osteoblastic cells grow quite actively without any indication of cytotoxicity. They begin to grow adhered to the bottom of the flask within 24 hours and remain the same in shape. The bone cells in the group of 0.304mg/ml grow remarkably around the compound materials. They are in the shape of classic osteoblastic cells that are overlapped into networks. Radioisotope 3H-TdR assay shows that after 48 hours, the CPC compounded with eucommia ulmoides extracts of 0.304mg/ml density is most effective in proliferating osteoblastic cells. Under scanning electron microscope, the group of 0.304mg/ml, after 48 hours, witnesses a larger amount of osteoblastic cells covering the surface of the compound materials. On the most dense area, cells grow in multiplayer and the inter-cell contact become close and frequent. This shows that the compound of CPC/ eucommia ulmoides extracts has positive effect on the proliferation ofosteoblastic cells.3. Putting the compound material with this density into the rabbit skull defects model and compare it with CPC without eucommia ulmoides. Observation is conducted for three consecutive months. None of the samples have acute or chronic immunologic rejection . X rays and scanning electron microscope indicate that the gap between the artificial bones and the natural bones grows smaller and smaller until finally they are connected with each other. The density grows gradually under shade. The artificial bones and the natural bones in the experimental group are closely linked with each other after 8 weeks and bone texture can be detected near the edge. In the 12th week, even the edge grows weak, which shows that pirt of the bone tissue has already grown into the material. Histological observation shows that with time going, collagen fibers become calcified. The new-born osteoid grow from the edge into the depth of the materials. The growth of new-born bones is rapid and some osteoid are formed. In the meantime, the materials in the pure CPC groups do not dissolve. There is a limited number of the new-born osteoid. Fiber structure remains the main part.Conclusion:CPC has nice physical functions and biocompatibility. Eucommia ulmoidesextracts are effective for the growth and proliferation of osteoblast. The compoundof these two can increase CPC artificial bone's conductivity and osteogenesis.
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