3D Printing And Forging Of TC4 Surfaces After SLA In An Animal Model Of Hyperglycaemia

Purpose:We studied the surface properties of 3D printed（German Concept Laser Mlab cusing R metal 3D printer）titanium implants and conventional wrought titanium implants by sandblasting acid etching（SLA）to improve their surface properties and to compare their ability to bond with bone after implantation in a hyperglycemic model rabbit and a healthy rabbit,respectively.This allows 3D printed personalized titanium implants and wrought titanium implants to be surface-treated to improve their osseointegration capabilities and to be better used in diabetic patients.Methodology:Pre-experiments were conducted to find out the conditions of sandblasting parameters and acid etching parameters,and to observe the surface morphology,hydrophilic analysis,roughness analysis and surface composition of 3D printed titanium alloy and wrought rolled titanium alloy after large particle sandblasting acid etching（SLA）treatment,so as to obtain the parameters that can make the surface of3D printed titanium alloy and wrought rolled titanium alloy achieve the relatively best surface properties.It was applied to the implants and implanted in hyperglycemic rabbits and healthy rabbits,and removed at 4,8,and 12 weeks after surgery,respectively,and hard tissue sections were made and stained with methylene blue acidic magenta dye.Subsequently,we measured and analyzed the bone implant contact rate and studied the osseointegration ability of the two implants in hyperglycemic rabbits and healthy rabbits and made a comparative study.Results:SEM microscopic observation shows that the surfaces of 3D printed titanium alloy and wrought titanium alloy after sandblasting and double acid etching has formed uniform and fine micro-nano-scale pore structure compared with the untreated surface,and removed the residue of sandblasting debris on the surface;the surface of titanium alloy after sandblasting and acid etching with oxalic acid has increased more"knife-sharp"surface structure and significantly increased hydrophilicity compared with the surface of single acid etching;The surface roughness was tested and found to meet the standard of 2-3μm for both Ra values,which has been proven in many relevant literature^[1]to be biocompatible and similar to most implants on the market;The results of animal experiments showed that the osseointegration rates of group A（hyperglycemic group）and group B（normoglycemic group）were not significantly different in the 3D printing group at 4w,the forging group at 8w,the 3D printing group and the forging group at 12w,and there were significant differences in the osseointegration rates of the forging group at 4w and the 3D printing group at 8w between groups A,B（P=0.044,P=0.047）,respectively,and the 3D printed TC4 implants were not significantly different from forged TC4 in terms of their osteogenic ability after acid etching with large particle sandblasting bicarbonate.Conclusion:The osseointegration ability of 3D printed TC4 and forged TC4 in vivo in hyperglycemic and healthy rabbits after the treatment with the new SLA treatment method derived from the previous experiments was not significantly different,and there was a significant advantage over the implant surface obtained by the previous SLA treatment method,providing an experimental basis for clinical improvement of the osseointegration rate of diabetic implants;There is no significant difference in the osseointegration ability of 3D printed TC4 compared to conventional wrought TC4 after surface SLA treatment.Based on the personalized design and fabrication features of 3D printing,it has the advantage of being able to design porous structures internally and better match with the defect site,which has a broader application prospect in the biomedical field.