| Objective:This study was aimed to evaluate the biocompatibility of (graphitized and non-graphitized)carbon/carbon composites+hydroxyap-atite (C/C+HA) coating implant materials made through isothermal chemical vapor deposition and plasma spraying and explore the feasibility of the composite material as implantation of bone tissue based on the body through the establishment of rabbit femur defect animal model in this experiment.Methods:Animal model of bone defect was established by drilling holes on the femoral condyle of the experimental animals.30 New Zealand rabbits were randomly divided into 5 groups:group A (control group), group B (non-HA coated non-graphitized C/C composite material group), group C (not-HA coated graphitized C/C composite material group), group D (HA coated non-graphitized C/C composite material group), and group E (HA coated graphitized C/C composite material group). The experimental materials to be studied were implanted in the right femoral condyle of experimental animals, and subjected to continuous observation for 8 weeks. X-ray photograph, histological staining and scanning electron microscopy were taken on 2,4,8 weeks after operation. The effects on the bone healing process in the body of the research materials were respectively observed, at the same time, comparison and correlation analysis were set.Results:1. Changes in vital signs and general:Experimental animals'wound healed well, in about 10 days.Body temperature, heart rate, respiration, fluctuated slightly during the first three days after the operation and stabilized gradually after.The animal behaved nomally with no obvious limitation.Weight, food intake, water intake, defecation and urination gradually increased compared with the preoperative condition.2. There were no surrounding tissue of material any inflammatory reaction after these subjects were implanted in the animals'femoral condyle. For 8 weeks after implantation during the observation period, histological and scanning electron microscopy showed:the surface of pure carbon/carbon composites without HA coated and the surface of carbon/carbon composites coated with HA, were performing well on the bone remodeling; but the latter, on which the thickness of fibrous connective tissue membrance is much smaller than the pure C/C composites, closer integration with bone tissue and the phenomenon of solid carbon particles free fall obvious reduced. Meanwhile, by comparison with non-graphite pure C/C composites, graphitized C/C composites exhibited relatively more superior in the growth of bone tissue and its role in promoting the surface of carbon particles to reduce the degree of loss than the non-graphite C/C composites.Conclusion:1. By comparing graphitized and ungraphitized materials, it can be seen the the graphitized carbon/carbon composites material works better in promoting bone tissue growth and reducing the freeing of carbon particles.2. C/C+HA coating composites have good biocompatility, and grearly reduced the possibility of releasing carbon particles. At the same time,it can have well function in the biological remodeling of bone morphology, and promoting the growth of trabecular bone, is a bone-repairing material with great potential.
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