A 3D printed gradient porous structure implant and its preparation method

Abstract

The present invention relates to a 3D printed gradient porous structure implant and a preparation method thereof. The implant prepared by this method has a porosity that increases radially and varies in a gradient. The external porosity of the gradient porous structure is relatively large and the elastic modulus is relatively small, which is equivalent to the elastic modulus of human bone tissue. It can effectively avoid the failure of the implant caused by stress shielding and the inflammation generated with the surrounding tissues, and is conducive to the inward growth and reproduction of bone tissue cells. The internal porosity of the gradient porous structure is relatively small and the elastic modulus is relatively large, with relatively high strength, making the implant more stable and reliable under load. The "outer sparse and inner dense" design structure can balance the relationship between the elastic modulus and strength.

Description

Technical Field

[0001] The present invention belongs to the field of root implant structures, and particularly relates to a preparation method for a 3D printed gradient porous structure implant and a porous structure implant. Background Art

[0002] Due to the characteristics of low specific gravity, high specific strength, low elastic modulus, corrosion resistance, and good biocompatibility of metallic titanium, it is widely used as a biomedical material in the field of dental implants. Currently, most dental implants are solid titanium. Although the elastic modulus of titanium is lower than that of other metal materials, it is still very high for biological bone. After being implanted into bone tissue, due to the large difference in elastic modulus between titanium and biological bone, stress shielding and stress concentration are likely to occur, resulting in disuse absorption of bone tissue and ultimately leading to the failure of implantation, increasing the pain of dental patients. To solve the problem of the mismatch in elastic modulus between metallic titanium and biological bone, some scholars have proposed to manufacture porous titanium implants to reduce the elastic modulus of the overall structure, which is indeed a good solution.

[0003] The elastic modulus of porous titanium structural materials is close to that of natural bone, and it has good osteoconductivity. It can guide bone tissue to grow into the pores to achieve biological fixation, promote bone bonding, and ensure the long-term stability after implanting the implant. Although a single porous structure can greatly reduce the elastic modulus of the structure, it also reduces the strength of the implant. Under the action of load, the implant is prone to fracture.

[0004] Therefore, how to overcome the shortcomings of the prior art and provide a preparation method for a porous structure implant that can take into account both low elastic modulus and high strength is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] The main object of the present invention is to provide a preparation method for a porous structure implant that can take into account both low elastic modulus and high strength. The implant prepared by this method has a porosity that increases radially and shows a gradient change. The external porosity of the gradient porous structure is larger and the elastic modulus is smaller, which is equivalent to the elastic modulus of human bone tissue. It can effectively avoid implant failure caused by stress shielding and inflammation with surrounding tissues, and is conducive to the inward growth and reproduction of bone tissue cells. The internal porosity of the gradient porous structure is smaller and the elastic modulus is larger, with higher strength, making the implant more stable and reliable under load. The "outer sparse and inner dense" design structure can balance the relationship between elastic modulus and strength.

[0006] To achieve the above object, in the first aspect of the present invention, a preparation method for a 3D printed gradient porous structure implant is provided. The method includes the following steps:

[0007] S1, constructing an overall three-dimensional model of the implant, specifically including:

[0008] S1-1. It is constructed using 3D modeling software. Referring to the parameters of the ITI implant system, a basic unit sector is designed. The basic unit sector has a gradient porous structure with a porosity increasing radially.

[0009] S1-2. Arrange and combine the basic unit sectors circumferentially to obtain a single-layer porous cylinder structure.

[0010] S1-3. Perform topological processing on the single-layer porous cylinder structure axially and stack it in a certain manner to obtain a multi-layer porous cylinder structure.

[0011] S1-4. According to the parameters of the ITI implant system, construct the neck structure and abutment structure of the implant at the top of the multi-layer porous cylinder structure to obtain the overall 3D model of the implant.

[0012] S2. Print the implant according to the overall 3D model, specifically including: importing the overall 3D model of the implant into a 3D printing device; enabling the 3D printing device to print layer by layer according to the overall 3D model of the implant until the implant is printed.

[0013] In the second aspect of the present invention, a 3D printed gradient porous structure implant prepared by the above method is provided.

[0014] The beneficial effects of the present invention are as follows:

[0015] 1. The preparation method of the 3D printed gradient porous structure implant provided by the present invention. The implant prepared by this method has a porosity increasing radially (showing a gradient change). The external porosity of the gradient porous structure is relatively large and the elastic modulus is relatively small, which is equivalent to the elastic modulus of human bone tissue. It can effectively avoid the failure of the implant caused by stress shielding and the inflammation generated with the surrounding tissues, and is beneficial for the growth and reproduction of bone tissue cells inward; the internal porosity of the gradient porous structure is relatively small and the elastic modulus is relatively large, having a relatively high strength, making the implant more stable and reliable under load. The "outer sparse and inner dense" design structure can balance the relationship between the elastic modulus and strength.

[0016] 2. Since the porous structure of the implant shows a gradient distribution and the connection and transition between the inner and outer layers are gentle, the stress distribution of the gradient porous structure implant is relatively uniform under load, and it can effectively avoid the formation of stress concentration of the implant under load.

[0017] 3. The porosity of the multi-layer porous cylinder structure in the gradient porous structure implant can be controlled by adjusting the pore wall width and sector angle, which is beneficial for the implementation of personalized implant design.

[0018] 4. The method of the present invention can precisely control the morphological structure, porosity and distribution mode of the pores. In the long run, it is beneficial to the long-term stability of the implant. The 3D printing technology of the present invention has great advantages in the preparation of porous structure materials. In the prior art, the preparation methods of porous titanium implants are generally traditional methods such as powder sintering, solid-state foaming, adding pore-forming agents, etc., and cannot achieve the above effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. And throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0020] Figure 1 is a schematic structural diagram of a basic unit sector;

[0021] Figure 2 is a side view of the structure of the basic unit sector;

[0022] Figure 3 is a schematic structural diagram of a single-layer porous cylinder structure;

[0023] Figure 4 is a schematic structural diagram of a multi-layer porous cylinder structure arranged in a linear arrangement from a single-layer porous cylinder structure;

[0024] Figure 5 is a schematic structural diagram of a multi-layer porous cylinder structure arranged in a spiral arrangement from a single-layer porous cylinder structure;

[0025] Figure 6 is a schematic structural diagram of a gradient porous structure implant;

[0026] Figure 7 is a relationship diagram of the elastic modulus of the gradient porous structure implant changing with the porosity;

[0027] Figure 8 is a stress nephogram of the gradient porous structure implant changing with the porosity and the relationship between the maximum equivalent stress and the yield strength under ANSYS static simulation.

[0028] Description of the reference numerals:

[0029] R is the angle of the basic unit sector; d1 is the height of the pore diameter; d2 is the width of the pore diameter; d3 is the width of the strut; d4 is the width of the pore wall; 100 is the basic unit sector, 200 is the single-layer porous cylinder structure, 300 is the multi-layer porous cylinder structure stacked by the linear arrangement of the single-layer porous cylinder structure, 400 is the multi-layer porous cylinder structure stacked by the spiral arrangement of the single-layer porous cylinder structure, 500 is the gradient porous structure implant, 501 is the neck structure of the gradient porous structure implant, and 502 is the abutment structure of the gradient porous structure implant. Detailed implementation manners

[0030] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present disclosure.

[0031] Schematic diagrams of various structures according to embodiments of the present disclosure are shown in the accompanying drawings. These figures are not drawn to scale, where for the purpose of clear expression, some details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary. In practice, there may be deviations due to manufacturing tolerances or technical limitations, and those skilled in the art can design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0032] In the context of the present disclosure, when a layer / component is referred to as being "on" another layer / component, the layer / component can be directly on the other layer / component, or there can be an intermediate layer / component between them. Additionally, if a layer / component is "on" another layer / component in one orientation, then when the orientation is reversed, the layer / component can be "under" the other layer / component.

[0033] The present invention will be further described below with reference to specific accompanying drawings.

[0034] As Figures 1-6 shown, a preparation method of a 3D printed gradient porous structure implant provided by a specific implementation manner of the present invention mainly includes the following steps:

[0035] S1. Construct the overall three-dimensional model of the implant, specifically including:

[0036] S1-1. Use three-dimensional modeling software to construct. Referring to the parameters of the ITI implant system, design the basic unit sector 100, and the basic unit sector 100 has a gradient porous structure with a porosity increasing radially.

[0037] S1-2. Arrange and combine the basic unit sectors 100 circumferentially to obtain a single-layer porous cylinder structure 200;

[0038] S1-3. Perform topological processing on the single-layer porous cylinder structure axially and stack it in a certain manner to obtain a multi-layer porous cylinder structure;

[0039] S1-4. According to the ITI implant system parameters, construct the neck structure 501 and abutment structure 502 of the implant at the top of the multi-layer porous cylinder structure to obtain the overall three-dimensional model of the implant;

[0040] S2. Print the implant according to the overall three-dimensional model, specifically including: importing the overall three-dimensional model of the implant into a 3D printing device; enabling the 3D printing device to print layer by layer according to the overall three-dimensional model of the implant until the implant is printed.

[0041] Through the above preparation method of the 3D printed gradient porous structure implant, according to the ITI implant system parameters, a gradient porous structure implant with an outer sparse and inner dense porosity is designed and prepared. Its elastic modulus is equivalent to that of human bone tissue, which can effectively avoid implant failure caused by stress shielding and the inflammation generated between the implant and the surrounding tissues, and improve the success rate of implanting the gradient porous structure implant 500. Moreover, the outer layer of the designed and prepared gradient porous structure implant 500 has a larger porosity and pore diameter, which can provide conditions for the growth and reproduction of bone tissue cells to grow inward. The inner layer has a low porosity, small pore diameter and high density, which can enhance the strength of the implant, making the implant more stable and reliable under load. Due to the gradient distribution of the porous structure of the implant, the connection and transition between the inner and outer layers are gentle, and the stress distribution of the gradient porous structure implant 500 is relatively uniform under load, which can effectively avoid the formation of stress concentration of the implant under load. The implant prepared by the present invention can effectively avoid implant failure caused by stress shielding compared with the traditional fully dense titanium alloy implant. At the same time, different pores can meet the spatial environmental conditions required for the adhesion and proliferation of osteoblasts, improve the bone integration ability, and endow the implant structure with good osteoconductivity, while also meeting the transportation of nutrients; compared with the porous implant with a single pore, when the porosity of the single porous titanium structure is relatively large, its strength is small, and it is prone to deformation and fracture in the actual implant environment, unable to meet the mechanical strength requirements during the implant process. The gradient porous structure implant prepared by the present invention can well balance the strength and elastic modulus.

[0042] As Figure 1 shown, in the preparation method of the 3D printed gradient porous structure implant provided in a specific embodiment of the present invention, the basic unit sector 100 includes a basic unit sector angle R of a certain size, a strut width d3, a pore wall width d4, a pore diameter width d2 and a pore diameter height d1.

[0043] The porosity of the multi-layered porous cylinder structure in the gradient porous structure implant can be controlled by adjusting the basic unit sector angle R, the strut width d3, the pore wall width d4, the pore diameter width d2, and the pore diameter height d1, which is beneficial to the implementation of personalized implant design.

[0044] In the present invention, the basic sector angle R can be 20° - 30°, the strut width d3 can be 0.1 - 0.3 mm, the pore wall width d4 can be 0.1 - 0.3 mm, the pore diameter width d2 can be 0.5 - 0.8 mm, and the pore diameter height d1 can be 0.4 - 0.8 mm. Among them, the dimensions of the strut width d3 and the pore wall width d4 can be the same or different.

[0045] In the present invention, the radius of the basic unit sector 100 can be 2 mm, and the thickness can be 1 mm.

[0046] As Figures 1-3 shown, in the preparation method of the 3D printed gradient porous structure implant provided in a specific embodiment of the present invention, the number of basic unit sectors 100 arranged circumferentially is determined according to the basic unit sector angle R.

[0047] As Figure 3 shown, in the preparation method of the 3D printed gradient porous structure implant provided in a specific embodiment of the present invention, the basic unit sectors 100 are arranged and combined circumferentially to obtain a single-layer porous cylinder structure 200.

[0048] As Figure 4 shown, in the preparation method of the 3D printed gradient porous structure implant provided in a specific embodiment of the present invention, the single-layer porous cylinder structure 200 is stacked axially to form a multi-layer porous cylinder structure 300 in a linear arrangement.

[0049] As Figure 5 shown, in the preparation method of the 3D printed gradient porous structure implant provided in a specific embodiment of the present invention, the single-layer porous cylinder structure 200 is stacked axially in a spiral arrangement to form a multi-layer porous cylinder structure 400.

[0050] The linear arrangement and the spiral arrangement can make the gradient porous gradient implant generate different stress-bearing modes, thereby changing the maximum equivalent stress and elastic modulus of the gradient porous gradient implant, and being applicable to different customization schemes.

[0051] In the preparation method of the 3D printed gradient porous structure implant provided in a specific embodiment of the present invention, the number of single-layer porous cylinder structures 200 stacked along the axial direction is determined according to the thickness of the basic unit sector 100. When designing according to different schemes, since the total size of the gradient porous structure implant is controlled within a certain range according to different customization schemes, the number of single-layer porous cylinder structures 200 stacked is 10-15, the height of the multi-layer porous cylinder structure is 9-11 mm, and the porosity of the gradient porous structure implant is 40%-95%, which can meet the needs of personalized customization of different schemes.

[0052] In the preparation method of the 3D printed gradient porous structure implant provided in a specific embodiment of the present invention, the 3D modeling software used is Solidworks, the export format of the overall 3D model of the implant is STL format, and the 3D printing device used can be selective laser melting (SLM) printing or electron beam melting (EBM) printing.

[0053] Another aspect of the present invention provides a gradient porous structure implant 500 prepared by the above method, as Figure 6 shown.

[0054] For the gradient porous structure implant 500 provided in a specific embodiment of the present invention, the printing material of the gradient porous structure implant 500 includes titanium, titanium alloy or composite material powder.

[0055] For the gradient porous structure implant 500 provided in a specific embodiment of the present invention, the printing material of the gradient porous structure implant 500 includes, but is not limited to, Ti, Ti-6Al-4V, TiMo alloy, TiNi alloy, and TiB / Ti composite material powder.

[0056] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0057] Example 1

[0058] Step 1: Using the Solidworks modeling software, referring to the parameters of the ITI implant system, design the gradient porous structure of the implant. First, design the basic unit of the gradient porous structure. The basic unit is the basic unit sector 100. The angle of the basic unit sector 100 is 24°, the sector radius is 2 mm, and the thickness is 1 mm. The pillar width d3 is designed to be 0.3 mm, the pore diameter height d1 is 0.4 mm, and the pore diameter width d2 is 0.54 mm.

[0059] Step 2: After designing the basic unit of the gradient porous structure, the basic unit sector 100 is arranged circumferentially in Solidworks using the rotational arrangement method, with the number of arrangements being 15. The arranged structure is combined to obtain a single-layer porous cylinder structure 200 with a certain thickness. At this time, the thickness of the single-layer porous cylinder structure 200 is 1 mm.

[0060] Step 3: Then, the single-layer porous cylinder structure 200 obtained in Step 2 is topologically processed in the axial direction using the line spiral arrangement method in Solidworks, with the stacking number being 13, to obtain a multi-layer porous cylinder structure 400 with a gradient porous structure. The multi-layer porous cylinder structure 400 is used as the cylinder at the root of the implant. At this time, the porosity of the multi-layer porous cylinder structure 400 is 44.02%.

[0061] Step 4: On the basis of the multi-layer porous cylinder structure 400 obtained in Step 3, the neck structure 501 and the abutment structure 502 of the gradient porous structure implant 500 are built. The neck structure 501 and the abutment structure 502 are built according to the implant system, and finally the overall three-dimensional model of the implant is obtained and exported in STL format for 3D printing.

[0062] Step 5: The three-dimensional model of the implant is imported into a 3D printing device. The technology used by the 3D printing device is the SLM technology, and the printing material of the 3D printing device is titanium powder. It is printed layer by layer according to the three-dimensional model of the implant until the gradient porous structure implant 500 is printed.

[0063] After testing, the maximum equivalent stress of the gradient porous structure implant 500 under the simulated oral mechanical environment is 49.64 MPa.

[0064] After testing, the yield strength of the gradient porous structure implant 500 is 247.61 MPa.

[0065] After testing, the elastic modulus of the gradient porous structure implant 500 is 33.28 GPa.

[0066] Example 2

[0067] Step 1: Using the Solidworks modeling software, referring to the parameters of the ITI implant system, the gradient porous structure of the implant is designed. First, the basic unit of the gradient porous structure is designed. The basic unit is the basic unit sector 100, the angle of the basic unit sector 100 is 30°, the sector radius is 2 mm, and the thickness is 1 mm. The strut width d3 is designed to be 0.25 mm, the pore height d1 is 0.6 mm, and the pore width d2 is 0.84 mm.

[0068] Step 2: After designing the basic unit of the gradient porous structure, use the rotational arrangement method in Solidworks to arrange the basic unit sector 100 circumferentially. The number of arrangements is 12. Combine the arranged structure to obtain a single-layer porous cylinder structure 200 with a certain thickness. At this time, the thickness of the single-layer porous cylinder structure 200 is 1 mm.

[0069] Step 3: Then perform topological processing on the single-layer porous cylinder structure 200 obtained in Step 2 in the axial direction. Use the line spiral arrangement method in Solidworks, and the stacking number is 10 to obtain a multi-layer porous cylinder structure 400 with a gradient porous structure. At this time, the porosity of the multi-layer porous cylinder structure 400 is 58.96%.

[0070] Step 4: On the basis of the multi-layer porous cylinder structure 400 obtained in Step 3, construct the neck structure 501 and the abutment structure 502 of the gradient porous structure implant 500. The establishment of the neck structure 501 and the abutment structure 502 is based on the implant system. Finally, obtain the overall three-dimensional model of the implant and export it in STL format for 3D printing.

[0071] Step 5: Import the three-dimensional model of the implant into a 3D printing device. The technology used by the 3D printing device is the SLM technology. The printing material of the 3D printing device is titanium powder. Print layer by layer according to the three-dimensional model of the implant until the gradient porous structure implant 500 is printed.

[0072] By placing the designed implant in the oral biomechanical environment through Ansys finite element simulation, the peripheral pore permeability is good, and the implant has good mechanical compatibility with the surrounding tissues, which can effectively reduce the harm caused by stress shielding.

[0073] After testing, the maximum equivalent stress of the gradient porous structure implant 500 in the simulated oral mechanical environment is 74.13 MPa.

[0074] After testing, the yield strength of the gradient porous structure implant 500 is 154.34 MPa.

[0075] After testing, the elastic modulus of the gradient porous structure implant 500 is 17.72 GPa.

[0076] Example 3

[0077] Step 1: Using Solidworks modeling software, referring to the parameters of the ITI implant system, design the gradient porous structure of the implant. First, design the basic unit of the gradient porous structure. The basic unit is the basic unit sector 100, the angle of the sector is 24°, the radius of the sector is 2 mm, and the thickness is 1 mm. The width d3 of the strut is designed to be 0.2 mm, the height d1 of the pore diameter is 0.6 mm, and the width d2 of the pore diameter is 0.63 mm.

[0078] Step 2: After designing the basic unit of the gradient porous structure, use the rotational arrangement method in Solidworks to arrange the basic unit sector 100 circumferentially. The number of arrangements is 15, and then perform a combination process on the arranged structure to obtain a single-layer porous cylinder structure 200 with a certain thickness. At this time, the thickness of the single-layer gradient porous cylinder 200 structure is 1 mm.

[0079] Step 3: Then perform topological processing on the single-layer porous cylinder structure 200 obtained in Step 2 in the axial direction. Use the linear arrangement method in Solidworks, and the stacking number is 12 to obtain a multi-layer porous cylinder structure 300 with a gradient porous structure. Use the multi-layer porous cylinder structure 300 as the cylinder at the root of the implant. At this time, the porosity of the multi-layer porous cylinder structure 300 is 72.87%.

[0080] Step 4: On the basis of the multi-layer porous cylinder structure 300 obtained in Step 3, construct the neck structure 501 and the abutment structure 502 of the gradient porous structure implant 500. The establishment of the neck structure 501 and the abutment structure 502 is based on the implant system. Finally, obtain the overall three-dimensional model of the implant and export it in STL format for 3D printing.

[0081] Step 5: Import the three-dimensional model of the implant into a 3D printing device. The technology used by the 3D printing device is the SLM technology, and the printing material of the 3D printing device is titanium powder. Print layer by layer according to the three-dimensional model of the implant until the gradient porous structure implant 500 is printed.

[0082] After testing, the maximum equivalent stress of the gradient porous structure implant 500 under the simulated oral mechanical environment is 113.69 MPa.

[0083] After testing, the yield strength of the gradient porous structure implant 500 is 85.76 MPa.

[0084] After testing, the elastic modulus of the gradient porous structure implant 500 is 8.09 GPa.

[0085] Example 4

[0086] Step 1: Using Solidworks modeling software, referring to the parameters of the ITI implant system, design the gradient porous structure of the implant. First, design the basic unit of the gradient porous structure. The basic unit is the basic unit sector 100, the angle of the sector is 24°, the radius of the sector is 2 mm, and the thickness is 1 mm. The width d3 of the strut is designed to be 0.15 mm, the pore height d1 is 0.7 mm, and the pore width d2 is 0.68 mm.

[0087] Step 2: After designing the basic unit of the gradient porous structure, use the rotational arrangement method in Solidworks to arrange the basic unit sector 100 circumferentially. The number of arrangements is 15. Combine the arranged structure to obtain a single-layer porous cylinder structure 200 with a certain thickness. At this time, the thickness of the single-layer gradient porous cylinder 200 structure is 1 mm.

[0088] Step 3: Then, perform topological processing on the single-layer porous cylinder structure 200 obtained in Step 2 in the axial direction. Use the linear arrangement method in Solidworks, and the stacking number is 12 to obtain a multi-layer porous cylinder structure 300 with a gradient porous structure. The multi-layer porous cylinder structure 300 is used as the cylinder at the root of the implant. At this time, the porosity of the multi-layer porous cylinder structure 300 is 83.99%.

[0089] Step 4: On the basis of the multi-layer porous cylinder structure 300 obtained in Step 3, construct the neck structure 501 and the abutment structure 502 of the gradient porous structure implant 500. The establishment of the neck structure 501 and the abutment structure 502 is based on the implant system. Finally, obtain the overall three-dimensional model of the implant and export it in STL format for 3D printing.

[0090] Step 5: Import the three-dimensional model of the implant into a 3D printing device. The technology used by the 3D printing device is the SLM technology. The printing material of the 3D printing device is titanium powder. Print layer by layer according to the three-dimensional model of the implant until the gradient porous structure implant 500 is printed.

[0091] After testing, the maximum equivalent stress of the gradient porous structure implant 500 under the simulated oral mechanical environment is 194.04 MPa.

[0092] After testing, the yield strength of the gradient porous structure implant 500 is 38.87 MPa.

[0093] After testing, the elastic modulus of the gradient porous structure implant 500 is 2.82 GPa.

[0094] Example 5

[0095] Step 1: Using Solidworks modeling software, referring to the parameters of the ITI implant system, design the gradient porous structure of the implant. First, design the basic unit of the gradient porous structure. The basic unit is the basic unit sector 100. The angle of the basic unit sector 100 is 24°, the sector radius is 2 mm, and the thickness is 1 mm. The strut width d3 is designed to be 0.1 mm, the pore diameter height d1 is 0.8 mm, and the pore diameter width d2 is 0.73 mm.

[0096] Step 2: After designing the basic unit of the gradient porous structure, use the rotational arrangement method in Solidworks to arrange the basic unit sector 100 circumferentially. The number of arrangements is 15. Combine the arranged structure to obtain a single-layer porous cylinder structure 200 with a certain thickness. At this time, the thickness of the single-layer porous cylinder structure 200 is 1 mm.

[0097] Step 3: Then, perform topological processing on the single-layer porous cylinder structure 200 obtained in Step 2 in the axial direction. Use the linear arrangement method in Solidworks, and the stacking number is 11 to obtain a multi-layer porous cylinder structure 300 with a gradient porous structure. The multi-layer porous cylinder structure 300 is used as the cylinder at the root of the implant. At this time, the porosity of the multi-layer porous cylinder structure 300 is 92.64%.

[0098] Step 4: On the basis of the multi-layer porous cylinder structure 300 obtained in Step 3, construct the neck structure 501 and the abutment structure 502 of the gradient porous structure implant 500. The establishment of the neck structure 501 and the abutment structure 502 is based on the implant system. Finally, obtain the overall three-dimensional model of the implant and export it in STL format for 3D printing.

[0099] Step 5: Import the three-dimensional model of the implant into the 3D printing device. The technology used by the 3D printing device is the SLM technology. The printing material of the 3D printing device is titanium powder. Print layer by layer according to the three-dimensional model of the implant until the gradient porous structure implant 500 is printed.

[0100] After testing, the maximum equivalent stress of the gradient porous structure implant 500 under the simulated oral mechanical environment is 310.85 MPa.

[0101] After testing, the yield strength of the gradient porous structure implant 500 is 12.13 MPa.

[0102] After testing, the elastic modulus of the gradient porous structure implant 500 is 0.60 GPa.

[0103] In the above examples, the corresponding elastic modulus E and theoretical yield strength σ of the gradient porous implant were calculated according to the Gibson-Ashby model and related theories:

[0104] (1)

[0105] (2)

[0106] where Es is the elastic modulus of solid titanium (110 GPa), σs is the compressive yield strength of solid titanium (607 MPa), φ is the porosity, represents the power.

[0107] The finite element analysis software used in the present invention is ANSYS Workbench 18.0. The basic parameters of the titanium material used are based on the characteristics of the previous research of the research team: density 4.46 g‧cm -3 , elastic modulus 110 GPa, compressive strength 819 MPa, tensile strength 894 MPa. For the three-dimensional finite element analysis carried out, the model adopted is a simplified implant. The implant material is selected as titanium. The mandible model is made of outer cortical bone and inner cancellous bone materials. The implant in the oral environment is divided into tetrahedral meshes. A denser mesh is used for the 1.5-mm thickness of the implant-bone tissue interface, and the mesh size of this part is set to 0.3 mm, while the mesh size of other parts is set to 0.5 mm. The same settings are used for the proposed examples. The implant body and neck, the implant neck and abutment teeth, and the cortical bone and cancellous bone are all set to bonded contact. During the simulation, the lower surface of the bone block model is set as a rigid constraint, that is, it is assumed that the mandible does not move. A vertical load of 200 N is applied to the implant mandible model, and the ANSYS software is used to analyze the maximum equivalent stress and strain and other required parameters of the implant under this load.

[0108] After analysis, the relationship between the elastic modulus of the gradient porous structure implants in Examples 1-5 and the porosity is as Figure 7 shown. It can be seen from Figure 7 that the porosities of the gradient porous structure implants in Examples 2, 3, and 4 are 59.86%, 72.87%, and 83.99% respectively, and the elastic moduli are 17.72 GPa, 8.09 GPa, and 2.82 GPa respectively. The elastic modulus of human cortical bone tissue is 13.7 GPa, and the elastic modulus of cancellous bone tissue is 1.30 GPa. Therefore, compared with the elastic modulus of titanium alloy being 110 GPa, the elastic modulus of the designed gradient porous implant 500 is closer to that of human bone tissue, which can effectively avoid stress shielding after implantation and cause implant failure.

[0109] After analysis, the stress nephograms of the gradient porous structure implants in Examples 1-5 under ANSYS static simulation with the change of porosity are as follows Figure 8 shown, and the relationship between the maximum equivalent stress and the yield strength with the change of porosity is as follows Figure 8 shown. From Figure 8 it can be seen that the maximum equivalent stresses of Example 1 and Example 2 are 49.64 MPa and 74.13 MPa respectively, and the yield strengths are 247.61 MPa and 154.34 MPa respectively. The maximum equivalent stress is much smaller than the material yield strength, which can ensure that the implant does not break or undergo permanent deformation in the oral stress environment and can ensure the strength of the material.

[0110] As mentioned above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A preparation method of a 3D printed gradient porous structure implant, characterized in that The method includes the following steps: S1. Construct the overall three-dimensional model of the implant, specifically including: S1-1. Use three-dimensional modeling software to construct a three-dimensional model. Referring to the parameters of the ITI implant system, design the basic unit sector. The basic unit sector has a gradient porous structure with the porosity increasing radially. The basic unit sector includes a certain sector angle, strut width, pore wall width, pore diameter width, and pore diameter height. The sector angle is 20° - 30°, the strut width is 0.1 - 0.3 mm, the pore wall width is 0.1 - 0.3 mm, the pore diameter width is 0.5 - 0.8 mm, and the pore diameter height is 0.4 - 0.8 mm. S1-2. Arrange and combine the basic unit sectors circumferentially to obtain a single-layer porous cylinder structure. The number of basic unit sectors arranged circumferentially is determined according to the sector angle. S1-3. Perform topological processing on the single-layer porous cylinder structure axially and stack it in a linear or spiral arrangement to obtain a multi-layer porous cylinder structure. S1-4. According to the ITI implant system parameters, construct the neck structure and abutment structure of the implant at the top of the multi-layer porous cylinder structure to obtain the overall three-dimensional model of the implant. S2. Print the implant according to the overall three-dimensional model, specifically including: Import the overall three-dimensional model of the implant into a 3D printing device; make the 3D printing device print layer by layer according to the overall three-dimensional model of the implant until the implant is printed.

2. The preparation method of the 3D printed gradient porous structure implant according to claim 1, wherein, The radius of the basic unit sector is 1.5 - 2.5 mm, and the thickness is 0.5 - 1.5 mm.

3. The preparation method of the 3D printed gradient porous structure implant according to claim 1, characterized in that, The number of single-layer porous cylinder structures arranged axially is determined according to the thickness of the basic unit sector. The height of the multi-layer porous cylinder structure is 9 - 11 mm, and the porosity of the gradient porous structure implant is 40% - 95%.

4. The preparation method of the 3D printed gradient porous structure implant according to claim 1, characterized in that, The three-dimensional modeling software is Solidworks. The export format of the overall three-dimensional model of the implant is the STL format. The technology used by the 3D printing device is selective laser melting (SLM) printing or electron beam melting (EBM) printing.

5. A 3D printed gradient porous structure implant, characterized in that, Obtained according to the preparation method described in any one of claims 1 - 4.

6. The 3D printed gradient porous structure implant according to claim 5, wherein The printing material of the gradient porous structure implant includes titanium, titanium alloy, or composite powder.

7. The 3D printed gradient porous structure implant according to claim 6, characterized in that, The printing material of the gradient porous structure implant includes Ti, Ti-6Al-4V, TiMo alloy, TiNi alloy, and TiB / Ti composite powder.

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