| Objectives:We use different size of gelatin microparticles (GP), as pore maker, to compound with calcium phosphate cements (CPC) for construction of macroporous CPC to repaire rabbit skull defects. The goal of this study was to assess the role of pore size on the property of GP/CPC and to investigate the possibility that if the material degradation rate, osteogenesis, physical and chemical properties of composite materials can be modified by varying the pore size.Methods:1. We utilized physical way to crush original gelatin particles into micro-ones, and then selected the appropriate size (A:50-100μm、B:100-200μm、C:200-300μm、D:300-450μm) by using the sample sieve. The ultrastructure of different size gelatin microparticles were observed with scanning electron microscope (SEM).2. Four different macroporous CPC were developed by mixing gelatin microparticles of four different size with CPC particles (5/95weight ratio). Setting time test, weight loss test, biological compatibility experiments and SEM were done to evaluate the properties of4groups composites.3. Twelve New Zealand white rabbits were used in this study to establish four8mm circular skull defects model, and filled four groups of GP/CPC composites into skull defects randomly. Every six rabbits were sacrificed at6and12weeks respectively. The skull samples were prepared and examined for general observation, HE staining and bone histology analysis. Results:The diameter of crushed gelatin mircroparticles were A:(76±23)μm、 B:(155■29)um, C:(246■32)um. D:(365■47)um. When compared with control group(14.2■4.7min), the setting times of4group of GP/CPC composits were obviously shorten:A:7.3眑.lmin> B:7.7■1.2min, C:6.6■1.2min, D:6.3■1.2min (P<0.05). In weight loss test, the increase of microparticles diameter of GP/CPC resulted in an increase in the degradation of composits in PBS. The percentage of the weight loss were A:2.79■0.22%, B:4.15■0.53%, C:5.92■0.87%> D:6.51■0.96%at the2nd week and the data were5.02■0.67%,7.90■0.84%,9.70■1.01%and10.01■1.22at the time of eighth week (PO.05).In animal experiments, the amount of new bone formation increased as time goes on. The C group (200-3OOum) GP/CPC composite enjoyed the highest percentage of new bone formation at both two time points (the sixth and the twelfth week), which were15.20■0.88%and29.86■0.62%. followed by the group D(12.71■0.73%and22.53+0.77%), B(9.10■1.09%and18.11+0.69%) and A (8.92+0.81%and14.40■0.97%)(PO.05)Conclusion:The degradation rate, osteogenesis and chemical properties of composites can be modified by adding5%wt different diameter gelatin microparticles to vary the pore size of GP/CPC composits. It seems that200-30Uum is an ideal pore size range.μμμμ... |
PDF Full Text Request