The Basic Research Of Polyetheretherketone With The Micropores Surface And Controllable Internal Meshes Promote Its Combination With Soft And Hard Tissues

The soft and hard tissue defect of oral and maxillofacial region caused by tumor,trauma and congenital defect has brought huge trauma to the patient’s body and mind,which has seriously affected the patient’s quality of life.Currently,one of the clinical commonly used way to restore patients with defect in the area of soft and hard tissue defect is transplantation of autologous bone with vascular flap or autologous bone graft,but this approach needs patients to accept twice or even more surgical trauma,and also faces the risk of surgical failure,high operation cost.Another common repair method is implant repair.At present,the most commonly used implant repair materials are titanium and its alloys.Cutting and 3D(three-dimenstional,3D)printed individualized titanium restoration can repair patients with maxillofacial defects,but high modulus of elasticity of titanium and its alloy make it not very suitable.Soft tissue around the implant easily form prone to the lumen of the fibers,and the die cavity,seriously will wear out soft tissue,while at the same time titanium and bone tissue can form good bone union,but due to its elastic modulus is much higher than the modulus of elasticity in cortical bone,in turn,making it easier for the bone tissue around implant under the action of stress barrier,appear the phenomenon of bone resorption.Until the appearance of polyether-ether-ketone(PEEK),the maxillofacial defect repair saw a new hope.PEEK is a thermoplastic semi-crystalline polymer with many excellent physical and chemical properties.It is also used in the medical field,mainly because of its elastic modulus similar to that of human cortical bone.It also has good corrosion resistance and biological safety,but PEEK itself is a chemically inert material.Due to its chemical inertness,PEEK as an implant is unable to form a good combination with the surrounding soft and hard tissues after implantation.Therefore,while continuing to study the 3D-printed PEEK and its composite materials,we need to combine the current 3D-printed PEEK technology with traditional technology to produce a PEEK implant with higher strength and precision structure that meets the current medical needs.Based on this,this project combines 3D printing technology with traditional injection molding technology to produce PEEK castings with fine and controllable internal structures to promote their ability to combine with surrounding soft and hard tissues after implantation,providing experimental and theoretical basis for future research and clinical transformation application.This research mainly includes the following three parts:Part 1 The preparation of PEEK specimen with surface micropores and internal network structureObjective:Based on the research on the methods and conditions of 3D printing resin substitution combined with traditional injection molding method to flip the designed PEEK casting with fine internal grid structure,the standard method of preparing PEEK implant by combining these two methods is summarized and obtained.Method:1.In the software Materialise Magics 22.0,the test pieces with regular internal grid structure are designed.The test pieces are divided into non-pore group PEEK(P)and PEEK1.0(P1.0),PEEK1.5(P1.5)and PEEK2.0(P2.0)with hole diameters of 1mm,1.5mm and 2mm,respectively.2.Use 3D printer to print the designed resin substitute.3.PEEK casting with designed internal mesh structure was obtained by embedding and injection molding.The best conditions for embedding method,cooling method after sintering,feeding amount and holding time before die-casting were screened by grouping.The basis for grouping was obtained through literature review.4.PEEK specimens were acid etched with 98%concentrated sulfuric.5.Micro-computed tomography(micro-CT)is used to detect whether the prepared specimen has a complete pre-designed structure.Results:1.Standard preparation conditions of PEEK specimen:computer design,resin replacement by 3D printing,two-step embedding,sintering for 40 minutes at 850℃,cooling down to room temperature with the furnace,adding PEEK raw materials with the mass of resin replacement,keeping heat for 15 minutes in the porcelain casting furnace at 400℃,pumping and die-casting,cooling to room temperature and cleaning.2.PEEK has a chalky rough surface after acid etching.3.The injection-molding specimens P,P1.0,P1.5 and P2.0 were consistent with the designed structure.Micro-CT results showed that there were no bubbles inside the specimens and the internal grid structure was clear and complete.Conclusion:The combination of 3D printing technology and traditional injection molding technology can completely fabricate PEEK implants with fine,controllable internal structure.Part 2 The study of PEEK material with surface micropores and internal network structure to promote the combination with soft tissueObjective:The disk-shaped PEEK casting produced by the combination of 3D printing technology and traditional injection molding technology was corroded with acid on the surface,and its surface micropores and internal mesh were endowed with a double-layer three-dimensional structure.The three-dimensional structure on the surface and inside was studied to promote the binding ability of PEEK specimen and soft tissue.Method:1.PEEK specimens P,P1.0,P1.5 and P2.0 were prepared according to the experimental methods and standards in part Ⅰ.2.The prepared PEEK specimens P,P1.0,P1.5 and P2.0 were taken for surface acid etching(using 98%concentrated sulfuric acid)to form a new experimental group:Sulfated PEEK(SP),Sulfated PEEK1.0(SP1.0),Sulfated PEEK1.5(SP1.5)and Sulfated PEEK2.0(SP2.0).3.Scanning electron microscope(SEM)and Atomic force microscope(AFM)were performed on P and SP of the experimental group in vitro to observe the change of surface morphology of PEEK casting after acid etching.4.The change of hydrophilicity was observed through the contact Angle experiment.5.Mechanical strength of 8 PEEK specimens was tested by anti-pressure test.6.The Human skin fibroblasts(Human skin fibroblasts,HSFs)spread on the surface of P and SP two specimen,and its adhesion by scanning electron microscope,and through the specimen leaching liquid culture cell to test specimen of the cell toxicity,through the reverse transcriptase-polymerase chain reaction(reverse transcription-polymerase chain reaction,RT-PCR)to detect adhesion in two kinds of cells on the surface of the specimen matrix changes of related genes.7.Eight groups of specimens were implanted subcutaneously into the back of New Zealand white rabbits,and after 4 weeks,histological sections were prepared and hematoxylin-eosin staining(HE)was observed.8.Partial samples were taken for the separation experiment of tissue and specimen.Results:1.The surface of PEEK specimen P,P1.0,P1.5 and P2.0 was chalkiness after acid etching,and a layer of interleaved microporous structure was formed under electron microscopy compared with the smooth surface before acid etching.The observation results under atomic particle microscopy were consistent with those under scanning electron microscopy.2.After acid etching,the contact Angle also decreased significantly,and the expression of acid etching adhered to more cells,and acid etching did not affect the cells.The rough surface promoted more cell adhesion and secreted more genes related to fibroblast.3.The hole structure reduced the mechanical strength of PEEK casting but was sufficient to be used as an implant.The mechanical strength of the P1.5 and SP1.5 groups was particularly prominent in the group with hole structure,and acid corrosion did not significantly reduce the mechanical strength of PEEK specimen.4.Animal experiment results show that the implanted P,not etched PEEK casting P1.0,P1.5 and different extent P2.0 lies in the part of the soft tissue in combination with the formation of the gap,and the acid corrosion of PEEK casting SP,SP1.0,SP1.5 and SP2.0 not seen obvious gap,and soft tissue ingrowth of different level the PEEK in the holes of the specimens,also formed the crisscrossed connected,which especially SP1.5 and SP2.0 group.5.The results of the separation experiment were consistent with the results of histological staining,with larger holes and more soft tissue growing into the PEEK specimen to form a stronger mechanical combination.Conclusion:1.The rough surface formed by acid etching is conducive to the early rapid adhesion of cells and reduces the formation of PEEK and the surrounding soft tissue blank cavities.2.The internal grid structure provides more space for soft tissue to grow in and forms a good mechanical combination with PEEK specimen.3.PEEK specimen’s surface and internal double-layered three-dimensional structure effectively promoted the mechanical combination of surrounding soft tissues.Part 3 The study of PEEK material with surface micropores and internal network structure to promote the combination with bone tissueObjective:After acid etching,the cylinder PEEK casting produced by combining 3D printing technology and traditional injection molding technology was endowed with a double-layer three-dimensional structure of surface micropores and internal grids,and the three-dimensional structure of the surface and internal structure was studied to promote the binding ability of PEEK specimen and surrounding bone tissue after implantation.Method:1.The cylindrical PEEK specimens P,P1.0,P1.5 and P2.0 were prepared according to the experimental methods and standards in part Ⅰ.2.Part of the cylindrical PEEK specimen P,P1.0,P1.5 and P2.0 prepared by the method in experiment 1 was taken for surface acid etching to form a new experimental group SP,SP1.0,SP1.5 and SP2.0.3.SEM and AFM were performed on P and SP of the experimental group in vitro to observe the changes of surface morphology.4.The change of hydrophilicity was observed through the contact Angle experiment.5.Mechanical strength of 8 specimens was tested by anti-pressure test.6.In addition,rat bone marrow mesenchymal stem cells(rBMMSCs)were planted on the surfaces of the two specimens,and their adhesion was observed by scanning electron microscopy.The adhesion and proliferation were observed by immunofluorescence staining.7.The final will be 8 groups of specimens were implanted into New Zealand white rabbit tibia head,drawn after 12 weeks,the sample of Micro-computer tomography(Micro-Computed tomography,Micro-CT)scanning after making a biopsy and picric acid acid fuchsin staining(Vangieson,VG),observation.8.Part of the implant samples out experiments to test its and the adhesion strength of the bone tissue.Results:1.The surface of PEEK specimen P,P1.0,P1.5 and P2.0 was chalkiness after acid etching,and a layer of interleaved microporous structure was formed under electron microscopy compared with the smooth surface before acid etching.The observation results under atomic particle microscopy were consistent with those under scanning electron microscopy.2.After acid etching,the contact Angle also decreased significantly,and more cells adhered to the surface after acid etching.Fluorescent staining results showed that more cells adhered to the surface after acid etching and their morphology was more stretched.3.The test results of pressure resistance showed that the hole structure reduced the mechanical strength of PEEK casting but was sufficient to be used as an implant,among which the mechanical strength of P1.0,P1.5,SP1.0 and SP1.5 was particularly prominent in the group with hole structure.4.Animal experiment results show that the implanted P,not etched PEEK casting P1.0,P1.5 and P2.0 have different degrees of touching part form the gap lies in the bone tissue,and the acid corrosion of PEEK casting SP,SP1.0,SP1.5 and SP2.0 not seen obvious gap,and bone tissue ingrowth of different level the PEEK in the holes of the specimens,also formed the crisscrossed connected,which SP1.5 and especially SP2.0 group,the separation experiment results consistent with the results of histological staining.Conclusion:1.The rough surface formed by acid etching is conducive to the early rapid adhesion of bone marrow mesenchymal stem cells and reduces the formation of fibrous cavities between PEEK and surrounding bone tissues.2.The internal grid structure provides more space for bone tissue to grow in,and forms a good mechanical combination with PEEK specimen.3.PEEK specimen’s surface and internal double-layered three-dimensional structure effectively promoted the mechanical combination of the surrounding bone tissue.summaryIn this experiment,the method of combining 3D printing and hot die casting was established,the important parameters in the process of this joint method were determined,and the PEEK specimen with internal tubular pore network structure was constructed.Meanwhile,the three-dimensional structure of micropores on the surface of PEEK specimen was endowed with the method of acid corrosion1.3D printing combined with hot die casting can rapidly and accurately prepare PEEK specimens with tubular pore network structure,which can provide a new way for clinical preparation of PEEK implants.2.Acid corrosion endowed the PEEK specimen surface with microporous structure,increased the roughness and hydrophilicity of the PEEK specimen surface,and significantly increased the adhesion of HSFs and rBMMSCs.3.The mechanical strength of PEEK specimens with tubular pore network structure is related to the tubular pore diameter.For the specimens designed in the soft tissue binding capacity test,only the pore diameter of 1.5mm can meet the mechanical strength requirements of the implant.However,the designed specimens with pore diameters of 1.0 and 1.5 can meet the mechanical strength requirements of the implant.4.PEEK specimens with both surface micropore structure and tubular pore network structure are conducive to the combination with surrounding soft tissues and bone after implantation,and the best combination with soft and hard tissues is when the pore diameter is 1.5mm.5.It provides a new scheme for the clinical application of PEEK to repair jaw defect.