| Objective:To explore the application of 3D printing technology in preparing biodegradable composite artificial bone scaffold,which contains biological activity glass（BAG）and CaSO4·0.5H2O of polylactic acid（PLA）,and carries on the experiment in vivo and in vitro,to verify its three-dimensional structure,biomechanical properties,degradation,biological compatibility,osteogenesis ability features,and its feasibility for alternatives to repair bone defect.Methods:3D printing technology was used to prepare rectangular porous scaffolds with the size of 3mm×10mm×15mm in accordance with the optimal material ratio.The experimental group was A polylactic acid composite artificial bone scaffold containing bioactive glass and calcium sulfate hemihydrate.The mass ratio was PLA:CaSO4·0.5H2O:BAG=5:2:1.The control group of polylactic acid scaffold without bioactive glass and calcium sulfate hemihydrate and the blank control group were set.The characteristics of scaffolds,such as biomechanics,porosity,in vitro degradation,biocompatibility and osteogenic properties of scaffolds constructed from different materials in two groups were studied and compared with the blank control group.Results:The 3D printer numerical control system ran the digital model file generated by the 3D image modeling of the support drawn by computer aided design（CAD）software,and printed the scaffold of 3mm×10mm×15mm layer by layer.The maximum tolerable strength of the two groups of scaffolds was determined by the universal material testing machine that experimental group of PLA scaffold containing bioactive glass and calcium sulfate hemihydrate was（65.11±1.97）MPa and control group of PLA without bioactive glass and calcium sulfate hemihydrate was（78.09±2.86）MPa.The maximum bearing strength of the two groups of materials is close to human bone tissue.The measurement of scaffolds porosity by gravimetric volume method was（64.76±1.55）%in the experimental group and（64.06±1.54）%in the control group,and there was no statistical difference between the two groups（P>0.05）.The degradation rate of the scaffolds in the two groups was determined by the mass change of the scaffolds in the simulated body fluid（SBF）,experimental group was（9.91±0.47）%,（21.20±0.92）%and（33.64±0.94）%at4,8 and 12 weeks,respectively.And the control group was（8.24±0.55）%,（17.66±1.29）%and（29.10±1.20）%at 4,8 and 12 weeks,respectively,and there was statistical difference between group A and B（P<0.05）.Biocompatibility of scaffold materials suggests that the in vitro cytotoxicity of the scaffold material determined by CCK-8 method,indicating that the toxicity grades of the experimental group and the control group were grade 1.There was no statistical difference in blood routine and biochemical indexes between the two groups,blank control group and the normal animals（P>0.05）,at 4 weeks after the implanting operation in tibia in two groups of healthy adult New Zealand rabbits,and pathological sections of liver,spleen and kidney were normal.At 20 weeks after surgery,bone mineral density examination showed that the experimental group A was superior to the control group B,and both the experimental group and the control group were superior to the blank control group,with statistically significant differences（P<0.05）.Molybdenum target X-ray examination and gemstone spectral imaging（GSI）scan were performed on the bone defect in the operative area at 4 weeks,12 weeks and 20 weeks after the operation.As time went by,the scaffold material gradually degraded,and the new bone tissue and bone calcium mineral in the defect were observed gradually increased,replacing the artificial bone scaffold material.According to the energy spectrum CT material measurement system,the calcium salt density of bone mineral in different groups was measured showed that the difference was statistically significant between the model side of A and the model side of B（P<0.05）,and the difference was statistically significant（P<0.05）when model side of A group and model side of B group were compared with the model side of the blank control group,at 20 weeks after the operation.The bone histopathological sections at 20 weeks after the operation showed that the scaffolds of the experimental group and the control group degraded gradually and slowly,and the internal bone tissue grew well.Conclusion:With the application of 3D printing technology,the PLA composite artificial bone scaffold containing BAG and CaSO4·0.5H2O was prepared,which has good three-dimensional structure,biomechanical properties,biocompatibility,degradation performance,osteogenic ability and other characteristics,provides a new choice for the optimization and improvement of bone defect repair materials. |
PDF Full Text Request