Pre-functionalized dental reconstruction additive manufacturing biomedical material and preparation method thereof

Abstract

The application discloses a pre-functionalized dental and maxillofacial reconstruction additive manufacturing biomedical material and a preparation method thereof, and belongs to the technical field of biomedical materials. The application analyzes the mechanical properties and stress transmission structure of natural jaw bones, takes a TPMS structure as a basic unit, and obtains a pure titanium support of bionic cortical bone and bionic cancellous bone on a biting surface and a bottom edge by adjusting the TPMS unit parameters through 3D additive printing technology, and constructs an implant basket on the biting surface according to the tooth loss condition, so that a pre-functionalized dental and maxillofacial reconstruction composite pure titanium biomedical material is finally obtained, and the jaw bone region of a truncated defect is simulated. Meanwhile, BMP-2 is modified to the surface of the pure titanium support through surface modification of the implant, and the microfluidic technology is used to manufacture calcium phosphate-loaded hydrogel microspheres, which are injected into the pure titanium support, so that the biological activation is accelerated to accelerate bone regeneration. Therefore, the application fills the functional repair blank of the current clinical truncated bone defect, and provides a new strategy for the research and development of a new generation of oral reconstruction materials.

Description

Technical Field

[0001] This invention belongs to the field of biomedical materials technology, specifically a composite pure titanium biomaterial for dentition reconstruction with prefunctionalized implant basket structure that matches the mechanical properties of natural bone tissue and is used to treat truncated bone defects. Background Technology

[0002] Large-area bone defects caused by trauma, infection, or bone tumor resection have always been a challenging clinical problem. Almost all truncated bone defects result in delayed healing or nonunion, significantly impacting patients' quality of life. Statistics show that globally, over 2.2 million bone graft surgeries are performed annually to treat bone defects in orthopedics, neurosurgery, and oral and maxillofacial surgery. Clinically, oral bone defects, especially extensive alveolar bone insufficiency, directly affect patients' oral prosthetic treatment, namely the reconstruction of masticatory function and aesthetic restoration, particularly for implant-supported prostheses requiring substantial alveolar bone volume. Current clinical procedures often involve harvesting iliac bone or fibula for autologous vascularized bone flap reconstruction. After the bone graft stabilizes, the subsequent implantation plan is determined based on the actual bone volume. However, the high resorption rate of the iliac bone and the insufficient thickness of the fibula limit the widespread application of this type of bone graft and restrict the possibility of subsequent implantation treatment for these patients. Furthermore, the staged surgery of bone grafting and implantation significantly prolongs the treatment cycle and increases costs. On the other hand, previous treatment strategies were mostly based on the concept of "bone-to-bone" fusion, but these have drawbacks such as poor stability and lengthy treatment processes. In recent years, titanium implants have been widely used in clinical practice due to their excellent biocompatibility. However, stress shielding problems caused by mismatched mechanical properties and poor "metal-bone" integration caused by biological inertness remain challenges in the clinical treatment of large-area bone defects. Therefore, exploring a titanium scaffold with an elastic modulus that matches that of natural bone tissue and has certain bioactivity, incorporating dental implant considerations in its design, and comprehensively taking into account both bone reconstruction and occlusal reconstruction, may provide a precise, minimally invasive, short-cycle, and low-cost solution to the current series of problems in the clinical treatment of truncated jawbone defects from a pre-functionalization perspective.

[0003] Addressing this clinical predicament, this invention aims to analyze the mechanical properties and force transmission structure of natural jawbone. Using TPMS (Tooth-Modified Microstructure) as the basic unit, and employing 3D additive printing technology, a pure titanium scaffold with biomimetic cortical bone reinforced at the occlusal surface and base, and biomimetic cancellous bone internally is obtained by adjusting the parameters of the TPMS unit. Implant baskets are then custom-constructed on the occlusal surface according to the tooth loss situation, ultimately yielding a pre-functionalized composite pure titanium biomaterial for jaw reconstruction, simulating the jawbone region with truncated defects. Simultaneously, through implant surface modification, human bone morphology protein (BMP-2) is modified onto the surface of the pure titanium scaffold. Microfluidic technology is used to manufacture hydrogel microspheres loaded with calcium phosphate, which are then injected into the pure titanium scaffold to achieve bioactivation and accelerate bone regeneration. Therefore, this invention fills the current gap in the functional repair of truncated bone defects in clinical practice and provides a new strategy for the development of next-generation oral reconstruction materials. Summary of the Invention

[0004] The purpose of this invention is to fill the clinical gap in the simultaneous functional reconstruction of the dentition and jaw in cases of truncated bone defects, and to propose a pre-functionalized additive manufacturing biomedical material for dentition and jaw reconstruction and its preparation method. This invention uses TPMS structures as basic units and utilizes 3D additive printing technology to obtain a pure titanium scaffold with biomimetic cortical bone reinforced at the occlusal surface and bottom edge, and biomimetic cancellous bone internally, by adjusting the parameters of the TPMS unit. Implant baskets are then custom-constructed on the occlusal surface according to the tooth loss situation. Simultaneously, BMP-2 titanium surface modification technology and bioactive microsphere modification technology are combined to complete the preparation of the pre-functionalized additive manufacturing biomedical material for dentition and jaw reconstruction.

[0005] The specific technical solution adopted in this invention is as follows:

[0006] In a first aspect, the present invention provides a method for preparing prefunctionalized dental reconstruction additive manufacturing biomedical materials, as detailed below:

[0007] S1: Based on the natural jawbone morphology and topology, a main body of the jaw reconstruction framework with TPMS as the basic structural unit was designed on the Soildworks software.

[0008] S2: Reserve an implantation site at the future implant site, and use a mesh structure as the interface for connecting with the TPMS structural unit in the main body of the dentition reconstruction framework to construct an implant basket;

[0009] S3: Based on the main body of the dental and jaw reconstruction framework, a perforated metal wing is designed as a fixation point with the buccal bone surface; a negative mold matching the implant neck thread is designed at the reserved implant site in the alveolar ridge cortical bone area.

[0010] S4: Import the prefunctionalized dentition reconstruction frameworks with different parameters designed after steps S1 to S3 into ANSYS software, set the relevant parameters with the elastic modulus of pure titanium, implant the implant basket at the reserved implant site, apply vertical and inclined masticatory stress, and observe the stress and strain inside the prefunctionalized dentition reconstruction frameworks with different parameters.

[0011] Meanwhile, prefunctionalized dentition reconstruction frameworks with implants of different parameters were placed into the bone defect and bound in the form of separation, semi-fixation and osseointegration, respectively, to simulate the early, middle and late stages of implantation. Vertical and inclined masticatory stresses were applied, and the stress distribution transmitted to the surrounding natural jawbone by the prefunctionalized dentition reconstruction frameworks with different parameters was observed. The effects of different parameters on the prefunctionalized dentition reconstruction frameworks on the healing period and after healing were evaluated.

[0012] Based on a comprehensive evaluation of the results from both sources, the model parameters for obtaining the optimal stress distribution in the prefunctionalized dentition reconstruction framework were selected.

[0013] S5: Based on the model parameters of the optimal stress distribution obtained in step S4, a series of prefunctionalized dental reconstruction titanium frameworks are manufactured using pure titanium powder as raw material and selective laser melting technology.

[0014] S6: The surface of the prefunctionalized dentition reconstruction titanium framework is cleaned and activated, then subjected to alkaline heat treatment with a strong alkali at high temperature, and then immersed in a PBS solution containing BMP-2 to complete the BMP-2 functional modification of the surface of the prefunctionalized dentition reconstruction titanium framework.

[0015] S7: Ink material is obtained by dissolving nano-sized calcium phosphate and photoinitiator in GelMA solution, and gel microspheres are manufactured using microfluidics technology;

[0016] S8: The gel microspheres are injected into the prefunctionalized dentition reconstruction titanium framework obtained in step S6 after functional modification with BMP-2 to complete the bioactive modification and obtain the prefunctionalized dentition reconstruction additive manufacturing biomedical material.

[0017] Preferably, in step S1, the parameters of the main body of the dental reconstruction framework are adjusted to regulate its structure and mechanical properties, so as to achieve a dense outer cortical layer with small pores and an inner cancellous layer with large pores, while satisfying the requirement that the strength and elastic modulus match the natural bone tissue.

[0018] Furthermore, the parameters include pore size, porosity, wall thickness, and structural units.

[0019] Preferably, in step S6, the surface of the prefunctionalized dental reconstruction titanium framework is cleaned and activated using deionized water, anhydrous ethanol, and acetone.

[0020] Preferably, in step S6, the strong base is a 5 mol / L sodium hydroxide solution.

[0021] Preferably, in step S6, the alkaline heat treatment refers to an oil bath at 60°C for 24 hours.

[0022] Preferably, the BMP-2 content in the PBS solution of step S6 is 10-50 mg / ml.

[0023] Preferably, in the ink material of step S7, the mass concentration of GelMA solution is 5%-20%, the volume fraction of calcium phosphate is 5%-20%, the volume fraction of photoinitiator is 0.5%, and the pH of the ink material solution is neutral.

[0024] In a second aspect, the present invention provides a prefunctionalized dental reconstruction additive manufacturing biomedical material obtained by any of the preparation methods described in the first aspect.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1) This invention organically combines dental implant restoration with bone tissue repair, and incorporates the design of the implant basket into the design of jawbone reconstruction to help the implant achieve initial stability. It achieves pre-functional restoration of two organs in one surgery, providing a new approach for the repair treatment of patients with truncated jawbone defects.

[0027] 2) Based on the metal TPMS structural unit, this invention matches the bone properties and mechanical characteristics of different regions of the jawbone, fully utilizes biomimetic design and the advantages of additive manufacturing to prepare a jawbone truncated repair and reconstruction composite material with stress-resistant shielding.

[0028] 3) This invention fully utilizes the advantages of BMP-2 in inducing MSCs to differentiate into osteoblasts in the early stage of osteogenic formation and nanoscale CPO in rapidly inducing biomimetic mineralization in the late stage of osteogenic formation. It adopts the microsphere system and titanium surface layer-by-layer self-assembly technology previously developed by the research group to achieve time-controlled dynamic slow release in terms of assembly method, matching the bone regeneration process and helping the composite material to achieve effective bone integration.

[0029] 4) The personalized prefunctionalized dental and jaw reconstruction biomaterial designed in this invention can be combined with a digital osteotomy surgical guide. Through the pin transfer technology, the fully digital treatment process for such patients can be improved. The lesion removal and dental and jaw reconstruction can be completed simultaneously in one surgery, which effectively shortens the treatment process and achieves precise and minimally invasive medical treatment. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the manufacturing process of the prefunctionalized dental and jaw reconstruction biomedical material of the present invention;

[0031] Figure 2 The design drawing is for a prefunctionalized dentition reconstruction framework; (a) is a front view and (b) is a sectional view.

[0032] Figure 3 A photograph of a prefunctionalized dental reconstruction framework manufactured using laser melting technology. Detailed Implementation

[0033] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly, provided that there is no mutual conflict.

[0034] like Figure 1 As shown, this invention provides a method for preparing prefunctionalized dental reconstruction additive manufacturing biomedical materials, the specific preparation method of which is as follows:

[0035] S1: Based on the natural jawbone morphology and topology, a dental and jaw reconstruction framework with TPMS as the basic structural unit was designed in Soildworks software.

[0036] In practical applications, the structure and mechanical properties of the dentition reconstruction framework are controlled by adjusting its parameters. This achieves a dense outer cortical layer with small pores and an inner cancellous layer with large pores, while simultaneously ensuring that its strength and elastic modulus match those of natural bone tissue. The parameters of the dentition reconstruction framework include pore size, porosity, wall thickness, and structural units.

[0037] S2: Reserve an implantation site at the future implant site, and use a mesh structure as the interface for connecting with the TPMS structural unit in the main body of the dentition reconstruction framework obtained in step S1 to construct an implant basket.

[0038] S3: Based on the main body of the dental reconstruction framework obtained in step S1, a perforated metal wing is designed as a fixation point with the buccal bone surface, and a negative mold matching the implant neck thread is designed at the reserved implant site in the alveolar ridge cortical bone area.

[0039] In practical use, the order of steps S2 and S3 has no impact. Perforated metal wings refer to ear-like structures placed on both sides of the main body of the dental reconstruction framework, with several holes spaced vertically on each ear, such as... Figure 2 and 3 As shown.

[0040] S4: After processing through steps S1 to S3, a prefunctionalized dentistry framework is obtained. The prefunctionalized dentistry frameworks with different parameters are imported into ANSYS software. The relevant parameters such as pore size, porosity, wall thickness and structural unit are set using the elastic modulus of pure titanium. The implant basket is implanted at the reserved implant site, and vertical and inclined masticatory stresses are applied. The stress and strain inside the prefunctionalized dentistry frameworks with different parameters are observed.

[0041] Meanwhile, prefunctionalized dentition reconstruction frameworks with implants of different parameters were placed into the bone defect and bound in the form of separation, semi-fixation and osseointegration, respectively, to simulate the early, middle and late stages of implantation. Vertical and inclined masticatory stresses were applied, and the stress distribution transmitted to the surrounding natural jawbone by the prefunctionalized dentition reconstruction frameworks with different parameters was observed. The effects of different parameters on the prefunctionalized dentition reconstruction frameworks on the healing period and after healing were evaluated.

[0042] Based on a comprehensive evaluation of the results from both sources, the model parameters for selecting prefunctionalized dental reconstruction frameworks that yield the optimal stress distribution were determined.

[0043] For example, in practical use, preoperative patient imaging data is first obtained through CBCT scanning to design the osteotomy location. After simulating bone removal during surgery, a prefunctionalized titanium scaffold for dentition reconstruction with specific pore size, porosity, wall thickness, and TPMS structural units is designed based on the patient's actual condition, cortical bone thickness, cancellous bone density, missing tooth position, and surrounding important anatomical structures. Simulated chewing forces are applied to the implant at both vertical and 45-degree angles after implant placement, and the stress distribution within the implant, scaffold, and scaffold on surrounding bone tissue is observed. Similarly, simulated chewing forces are applied to the scaffold, and the stress distribution within the scaffold and scaffold on surrounding bone tissue is observed. Parameters without obvious red stress concentration areas are selected as the final printing parameters.

[0044] S5: Based on the model parameters of the optimal stress distribution obtained in step S4, a series of prefunctionalized dental reconstruction titanium frameworks are manufactured using pure titanium powder as raw material and selective laser melting technology.

[0045] like Figure 1 As shown, in practical use, this step can be achieved using a laser melting 3D printer.

[0046] S6: The surface of the prefunctionalized dentition reconstruction titanium framework obtained in step S5 is cleaned and activated, then subjected to alkaline heat treatment with a strong alkali at high temperature, and then immersed in a PBS solution containing BMP-2 to complete the BMP-2 functional modification of the surface of the prefunctionalized dentition reconstruction titanium framework.

[0047] In practical applications, cleaning and activation can be achieved using deionized water, anhydrous ethanol, and acetone. A strong alkali can be used, such as a 5 mol / L sodium hydroxide solution. Alkali heat treatment refers to an oil bath at 60°C for 24 hours. The BMP-2 content in the PBS solution is 10-50 mg / ml.

[0048] S7: Calcium phosphate and photoinitiator are dissolved in GelMA solution to obtain ink material, and gel microspheres are manufactured using microfluidic technology.

[0049] In practical applications, the ink material contains 5%-20% GelMA solution by mass, 5%-20% calcium phosphate by volume, 0.5% photoinitiator by volume, and a neutral pH. For example... Figure 1 As shown, microfluidics technology can be implemented based on DLP photopolymerization printers.

[0050] S8: Inject the gel microspheres obtained in step S7 into the prefunctionalized titanium scaffold for dentition reconstruction obtained in step S6 after functional modification with BMP-2, to complete the bioactive modification and obtain the prefunctionalized additive manufacturing biomedical material for dentition reconstruction, such as... Figure 3 As shown.

[0051] In practical use, the gel microspheres can be placed into a 10mL syringe and then injected (generally until the syringe is full) into the prefunctionalized dental reconstruction titanium framework modified with BMP-2 to complete the bioactive modification.

[0052] The preparation method of the material of the present invention will be further illustrated by the following examples.

[0053] Example

[0054] This embodiment provides a method for preparing prefunctionalized dental reconstruction additive manufacturing biomedical materials. The specific steps of this method are as follows:

[0055] 1) Design of the main body of the dental reconstruction framework

[0056] CBCT scans were performed on the patient's jawbone lesions to design the osteotomy range. Based on the natural jawbone morphology and topology of the region, a dental and jaw reconstruction framework with TPMS as the basic structural unit was designed on Soildworks software. The structure and mechanical properties of the overall framework were controlled by adjusting parameters such as pore size, porosity, wall thickness, and structural units. This achieved a dense cortical layer with small pores on the outside and a cancellous layer with large pores on the inside, while ensuring that the strength and elastic modulus of the region matched those of the natural bone tissue.

[0057] 2) Design the planting basket structure

[0058] Based on the bone fragments to be removed and the location of the missing teeth, implantation sites are reserved at the future implant sites, with a mesh structure serving as the interface for connection with the TPMS structural unit of the dentition reconstruction framework; a negative mold matching the implant neck thread is designed at the expected implant site in the alveolar ridge cortical bone region.

[0059] 3) Design metal side wings

[0060] Based on CBCT data, perforated metal wings were designed on both sides of the main body of the dental reconstruction framework to serve as fixation points to the buccal bone surface, avoiding important anatomical locations and adjacent tooth roots.

[0061] 4) Finite element mechanical analysis to optimize support parameters

[0062] Pre-functionalized dentistry frameworks with different parameters were imported into ANSYS software. The pore size, porosity, wall thickness, and structural units were set using the elastic modulus of pure titanium. Implants were inserted at pre-reserved implant sites, and vertical and oblique masticatory stresses were applied. The stress and strain within different frameworks were observed. Simultaneously, dentistry frameworks with implants were placed within bone defects, and binding was achieved using separation, semi-fixation, and osseointegration methods to simulate the early, middle, and late stages of implantation. Vertical and oblique masticatory stresses were applied, and the stress distribution transmitted from the framework to the surrounding natural jawbone was observed. The effectiveness of different frameworks in providing stress shielding during and after healing was evaluated. Based on the combined results of both methods, model parameters that yielded the optimal stress distribution were selected.

[0063] 5) Printing and manufacturing of prefunctionalized dental reconstruction frameworks

[0064] Using pure titanium powder as raw material, a prefunctionalized dental reconstruction titanium framework with the optimal parameters is manufactured using selective laser melting technology.

[0065] 6) Surface treatment of prefunctionalized dental reconstruction framework

[0066] The titanium scaffold surface was cleaned and activated using deionized water, anhydrous ethanol, and acetone for 20 minutes each. Then, it was subjected to alkaline heat treatment at high temperature (60℃ oil bath for 24 hours) with 5 mol / L sodium hydroxide solution, and then immersed in PBS solution containing BMP-2 (10-50 mg / ml) to complete the BMP-2 functional modification of the titanium scaffold surface.

[0067] 7) Preparation of controlled-release microspheres

[0068] GelMA (60% substitution rate) was dissolved in physiological saline under sterile conditions to obtain a 10% (w / w) GelMA solution. A photoinitiator (LAP, 0.5% (v / v)) and nano-sized calcium phosphate (10% (v / v)) were dissolved in the GelMA solution of the above concentration to obtain a microsphere prepolymer solution. Since the microsphere solution was weakly acidic at this point, the pH was adjusted to neutral (pH 7.4 in this example) by adding an appropriate amount of sodium hydroxide to obtain the ink material. This ink material was then filtered through a 0.22 μm filter to obtain a sterile electro-sprayed microsphere prepolymer solution. Microsphere particles with a diameter of approximately 1-5 mm were prepared using microfluidic technology.

[0069] 8) Microsphere loading of prefunctionalized dentistry framework

[0070] The gel microspheres were placed into a 10mL syringe and injected evenly into the porous titanium scaffold to fill the entire scaffold body, avoiding the planting basket area, thus completing the bioactive modification.

[0071] 9) Application of prefunctionalized dental reconstruction biomedical materials

[0072] Clinically, after the lesion area is removed using an osteotomy guide plate, pre-functionalized dental and jaw reconstruction biomedical materials are implanted into the surgical area, fixed with titanium screws, and then implanted with a specific type of pre-made implant to complete simultaneous dental and jaw reconstruction and restoration.

[0073] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A method for preparing prefunctionalized dental reconstruction additive manufacturing biomedical materials, characterized in that, Specifically as follows: S1: Based on the natural jawbone morphology and topology, a main body of the jaw reconstruction framework with TPMS as the basic structural unit was designed on the Soildworks software. S2: Reserve an implantation site at the future implant site, and use a mesh structure as the interface for connecting with the TPMS structural unit in the main body of the dentition reconstruction framework to construct an implant basket; S3: Based on the main body of the dental and jaw reconstruction framework, a perforated metal wing is designed as a fixation point with the buccal bone surface; a negative mold matching the implant neck thread is designed at the reserved implant site in the alveolar ridge cortical bone area. S4: Import the prefunctionalized dentition reconstruction frameworks with different parameters designed after steps S1~S3 into ANSYS software, set the relevant parameters with the elastic modulus of pure titanium, implant the implant basket at the reserved implant site, apply vertical and inclined masticatory stress, and observe the stress and strain inside the prefunctionalized dentition reconstruction frameworks with different parameters. Meanwhile, prefunctionalized dentition reconstruction frameworks with implants of different parameters were placed into the bone defect and bound in the form of separation, semi-fixation and osseointegration, respectively, to simulate the early, middle and late stages of implantation. Vertical and inclined masticatory stresses were applied, and the stress distribution transmitted to the surrounding natural jawbone by the prefunctionalized dentition reconstruction frameworks with different parameters was observed. The effects of different parameters on the prefunctionalized dentition reconstruction frameworks on the healing period and after healing were evaluated. Based on a comprehensive evaluation of the results from both sources, the model parameters for obtaining the optimal stress distribution in the prefunctionalized dentition reconstruction framework were selected. S5: Based on the model parameters of the optimal stress distribution obtained in step S4, a series of prefunctionalized dental reconstruction titanium frameworks are manufactured using pure titanium powder as raw material and selective laser melting technology. S6: The surface of the prefunctionalized dentition reconstruction titanium framework is cleaned and activated, and then subjected to alkaline heat treatment with 5 mol / L sodium hydroxide solution in an oil bath at 60°C for 24 h, and then immersed in PBS solution containing BMP-2 to complete the BMP-2 functional modification of the surface of the prefunctionalized dentition reconstruction titanium framework. S7: An ink material is obtained by dissolving nano-sized calcium phosphate and a photoinitiator in a GelMA solution, and then fabricating gel microspheres using microfluidic technology; in the ink material, the mass concentration of the GelMA solution is 5%-20%, the volume fraction of the nano-sized calcium phosphate is 5%-20%, and the volume fraction of the photoinitiator is 0.5%; S8: The gel microspheres are injected into the prefunctionalized dentition reconstruction titanium framework obtained in step S6 after functional modification with BMP-2 to complete the bioactive modification and obtain the prefunctionalized dentition reconstruction additive manufacturing biomedical material.

2. The method for preparing prefunctionalized dental reconstruction additive manufacturing biomedical materials according to claim 1, characterized in that, In step S1, the parameters of the main body of the dental reconstruction framework are adjusted to regulate its structure and mechanical properties, so as to achieve a dense outer cortical layer with small pores and an inner cancellous layer with large pores, while ensuring that the strength and elastic modulus match the natural bone tissue.

3. The method for preparing prefunctionalized dental reconstruction additive manufacturing biomedical materials according to claim 2, characterized in that, The parameters include pore size, porosity, wall thickness, and structural units.

4. The method for preparing prefunctionalized dental reconstruction additive manufacturing biomedical materials according to claim 1, characterized in that, In step S6, the surface of the prefunctionalized dental reconstruction titanium framework is cleaned and activated using deionized water, anhydrous ethanol, and acetone.

5. The method for preparing prefunctionalized dental reconstruction additive manufacturing biomedical materials according to claim 1, characterized in that, The BMP-2 content in the PBS solution of step S6 is 10-50 mg / ml.

6. The method for preparing prefunctionalized dental reconstruction additive manufacturing biomedical materials according to claim 1, characterized in that, In the ink material of step S7, the solution pH is neutral.

7. A prefunctionalized dental reconstruction additive manufacturing biomedical material obtained by the preparation method according to any one of claims 1 to 6.

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