| Biomedical titanium has the characteristics of low density,high specific strength,and good corrosion resistance.It can be used to repair and reconstruct the damaged bone in human body.However,due to insufficient activity,it is difficult to form osseous binding between dense titanium and bone,resulting in poor osseous integration effect,and there are some problems such as implant dislocation and weak interface bonding caused by biomechanical mismatch.The construction of porous structure can not only improve the mechanical fit,but also facilitate the inward growth of bone cells and new bone tissue and improve the effect of bone integration.However,there are few reports on the effect of pore structure characteristics on the cellular compatibility of porous titanium in vitro and the bone growth ability of porous titanium in animal models of femur defect.Based on the above problems,this paper aims to explore the structural characteristics,mechanical compatibility,activity,and bone integration ability of porous titanium under different porosity,and obtain the optimal porosity to promote bone integration ability.Therefore,the biomedical porous titanium was prepared by discharge plasma sintering technology without adding binder.The influence of sintering temperature on the structural characteristics and mechanical properties of porous titanium was studied,and a reasonable sintering temperature was selected.At this sintering temperature,lowmodulus porous titanium with different porosity was obtained by appropriately regulating the content and size of pore-forming agent.Pore structure evolution,mechanical properties,electrochemical corrosion properties and mineralization properties of porous titanium with different porosity were explored,and the mechanism of influence of porosity on the activity and bone integration ability of porous titanium was discussed.Conclusions were drawn as follows:The porous titanium was prepared by SPS sintering technology.With the increase of sintering temperature,the porosity and average pore size of porous titanium decreased,and the porous titanium contracted violently when the temperature was too high.The yield strength and compressive elastic modulus of porous titanium increased slowly with increasing temperature.By comparing the sintering temperature of 1050 ℃,the porous titanium has good mechanical compatibility(yield strength :143 MPa,elastic modulus :6.0 GPa)and the optimal pore size(50 μm～550 μm)suitable for the growth of tissue cells.The ability of porous titanium to induce apatite formation increases with increasing porosity.When the sintering temperature is 1050℃,the pore connectivity of porous titanium increases significantly with the increase of porosity,and the average pore size increases from 213.2 μm to 276.1 μm.The mechanical strength decreases sharply with the increase of pore connectivity,the yield strength decreases from 146 MPa to 36 MPa,and the elastic modulus decreases from 4.2 GPa to 0.9 GPa.The corrosion process of porous titanium is accelerated with the increase of porosity in simulated body fluid(SBF solution),and the mineralization ability of porous titanium is enhanced with the increase of porosity.The behavior of bone marrow mesenchymal stem cells(BMSCs)on porous titanium surfaces with different porosity showed that porous titanium showed no toxicity to BMSCs and showed good biocompatibility.Combined with BMSCs proliferation experiment,the increase of porosity is conducive to the adhesion and proliferation of BMSCs,and the extension of the "pseudopodia" of cells is obvious,and the cell activity is enhanced.In the femur defect model,with the increase of porosity,the new bone volume fraction and bone mineralization density at the interface between the porous titanium implant and bone increased significantly,and cells and bone tissues grew into the pores obviously,showing excellent bone conduction ability.The mechanical push-out experiment showed that the binding strength of the implant interface increased with the increase of porosity,and the porous titanium implant realized osseous bonding with bone tissue,and the bone integration ability of porous titanium was enhanced.In conclusion,the low-modulus biomedical porous titanium prepared by Spark Plasma Sintering(SPS)technology has a mechanical strength consistent with that of implants,and the porous titanium with a porosity of 60% shows good biological activity and integration ability,which has potential application value in the field of orthopedic implants. |
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