| ObjectiveWith the materials science and the development of bone tissue engineering, synthetic bone graft material tends to replace autologous, allogeneic bone grafting material, various clinical applications of bone defects. Dense bioceramics have better mechanical properties, can play the role of support and support, but because it does not exist for tissues and cells to the growth of micro-structure, so its biological properties are poor. At present the main clinical application of biological control of micro porous bioceramics. This micro-structure according to the needs of the growth of cells and tissues, which were produced complete control and can control the degree of degradation of the material. But it has poor mechanical properties, can not force parts and organs to support the role played good, so far only as a porous bioceramic filler material and non-load-bearing parts of the conductive material tissue growth, In order to solve the contradiction between the above, we must have good mechanical properties, but also has good biological properties. By analyzing the structure of natural bone, found that the mechanical properties of bone due to its excellent compact bone and cancellous bone of the composite structure; this study is inspired in its enhanced production of the porousβ-TCP bioceramics and model validation through their bone integration of animal, biodegradable and bio-mechanical properties.Methods1. Preparation of enhanced porous bioceramicsAccording to the product shape and size, making the appropriate split mold, depending on the product's uses and the methods used, are free to design the volume reinforcement content; or a formula determined by the volume reinforcement content.It can use the slip casting, compression molding or die - grouting collaboration to produce the body forming of enhanced ceramic. Enhanced sintering ceramic body placed in the furnace and gradually heated to 200℃to 400℃gasification to eliminate organic matter, and then continue to heat up to 800℃to 1300℃sintering ceramics. The dense and porous ceramic contains two parts. Dense part of the major role to play to increase the mechanical strength, while the porous part of the main cell and tissue ingrowth to play the guiding role of revascularization can be obtained at the same time adequate blood supply nutrients to the formation of new organizations, the corresponding function. The enhanced dense ceramic parts may contain micropores, pore rate of 0.1%-20%. The reinforcement of the porous part of the pore size of 50-1000μm, porosity rate of 50% to 85%, within the connection hole diameter 20-500μm, pore communication rate of 10% to 100%.2. The establishment of animal models24 New Zealand white rabbits were randomly divided into two groups: A group for the experimental group, the enhanced porousβ-TCP Bioceramics Group; B, control group, the porousβ-TCP bioceramics group. Each group were 12. Each rabbit underwent bilateral femoral P-TCP bioceramic implantation into the different types ofβ-TCP bioceramics. 4,12,24 weeks after surgery, four rabbits in each group were killed and remove samples, retained backup.3. Determination of osteointegrational abilityBone mineral content of bone defect measured:4,12,24 weeks after surgery animals were killed, died with a Norland XR-36-based small animal bone density measuring apparatus and test software in Animal bilateral radial bone mineral content of bone defects.Histological examination:Three groups were 4,12 and 24 weeks after surgery with the execution of air injection 1/3 animals. The surgical site 1/3 of the femur was removed and then the samples after the longitudinal cutting hard tissue and Ponceau staining and morphology observation. 4. Determination of biodegradabilityThe specimen preparation for the hard tissue, X-ray micrograph, the basis for various organizations in the X-ray different in light transmission by computer image processing software gives the result.5. Determination of biomechanical propertiesTo remove the two end cylindrical specimens polished. Measuring pressure area, the test piece vertically in the MTS855 type biomechanical testing machine (USA MTS), the measured compression strength, load speed lmm/min, until the cylinder burst, recorded when the specimen limit load of damage calculate the ultimate compressive strength.Results1. Osteointegrational abilityThe day after surgery and 4 weeks of bone mineral density was no significant difference compared (P>0.05),12 weeks,24 weeks, bone mineral density values of the experimental group than control group (P<0.05). With time, the two groups of bone mineral content increasing. The other will be 24 weeks the experimental group and control group patients bone mineral density values measured before the normal value (0.3375±0.0290) for one-way analysis of variance (One-Way ANOVA), found no significant difference between the three (F=3.186, P=0.062), bone mineral content at this time two groups have close to normal.2. BiodegradabilityEnhanced central porous part of the P-TCP degradation faster degradation of the surrounding dense part of the slow degradation of the substance of their biological ceramic slower than the porous type, the result was statistically significant compared with the pure porous, its circumference changes little to maintain good form. 3. Biomechanical propertiesEnhanced porous bioceramic reduce their intensity over time was not significant, the strength of the node at each time stronger than the porous type, the result was statistically significant.ConclusionsEnhanced porous bioceramics with good mechanical properties, can play the role of support and support, while there is suitable for the growth of micro-tissue and cell structure, so it is essential to maintain the biological properties of porous ceramics, such as biodegradable, bone conductivity, etc., while its mechanical properties have been greatly enhanced, the force can play a better part of a supportive role. Can be enhanced so that the porous bio-ceramic bearing bone defect site that has a more promising future. |
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