A method for the preparation of an interpenetrating phase ceramic dental material

Abstract

The application discloses a preparation method of an interpenetrating phase ceramic dental material and belongs to the technical field of biomedical materials. The application is based on the porous foam structure and cavity tissue of bird skeletons for biomimetic design, two kinds of biomimetic bird bone structures combining the characteristics of annular hyoid structures and cavity tissues are established, and according to the bird skull cooperative damping mechanism, a mortise and tenon structure with the characteristics of cooperative bearing and buffering is constructed, the structure has more excellent mechanical bearing performance and deformation stability compared with a traditional structure. The zirconium oxide-hydrogel interpenetrating phase material prepared by a photo-crosslinking method, the composite design of the soft phase and the hard phase material not only significantly improves the energy absorption characteristics of the material, but also effectively improves the fracture toughness of the dental material. On this basis, a functional coating is constructed on the surface of the material by using a sol-gel dip coating process, and the problems of insufficient corrosion resistance and wear resistance of the dental material in the oral environment are further solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of biomedical materials, and particularly relates to a preparation method of an interpenetrating phase ceramic dental material. BACKGROUND

[0002] Zirconia ceramics have become a key material in modern dental restoration due to their excellent biocompatibility, high strength and high wear resistance. However, the Young's modulus of traditional dense zirconia is much higher than that of natural dentin, which easily leads to stress shielding effect and may cause excessive wear of the opposing teeth. More importantly, its inherent brittleness and crack sensitivity limit its long-term reliability under dynamic occlusal load.

[0003] In recent years, with the development of additive manufacturing technology, some researchers have applied classic pyramid lattice structure, traditional body-centered cubic structure BCC and traditional face-centered cubic structure FCC to dental materials. However, the above structures are insufficient in load and prone to stress concentration leading to failure, and thus cannot serve effectively for a long time. Therefore, a new structure design form is needed to make up for such defects, and bionic design has been proven to have better mechanical feasibility than traditional structures in medical implants, aerospace, automotive protection and other fields.

[0004] Dental restorations are subjected to complex cyclic masticatory forces and impact loads in the oral environment for a long time, and the fracture toughness of the material directly determines its clinical service life and reliability. The traditional toughening mechanism of zirconia ceramics mainly depends on phase transformation toughening, which has the risk of aging in the later service period, and the inhibition ability of crack propagation is limited. In recent years, the unique three-dimensional interpenetrating network structure of interpenetrating phase heterogeneous structure materials can realize multiple toughening mechanisms: when the main crack propagates in the hard phase skeleton, the flexible soft phase network absorbs energy by deformation, and effectively transmits and disperses stress through the two-phase interface.

[0005] In addition, in the complex oral chemical and mechanical environment, the long-term service performance of the material faces severe challenges, and the interfacial corrosion resistance and wear resistance of the material directly determine the clinical life and functional reliability of the restoration. Although the use of yttria as a stabilizer to stabilize zirconia (3Y-TZP) has excellent mechanical properties at room temperature, it has a long-term "low temperature aging" phenomenon in the oral warm and humid environment. Although the problem of "low temperature aging" can be alleviated by increasing the yttria content in zirconia or using alumina-based composite technology to make composite materials, the high toughness is often sacrificed. The coating preparation technology based on surface modification is expected to solve such problems without affecting the mechanical properties and weight of the material. SUMMARY

[0006] In view of the above problems existing in the prior art, the present application aims to provide a preparation method of an interpenetrating phase ceramic dental material.

[0007] In order to solve the above problems, the technical scheme adopted by the present application is as follows:

[0008] A preparation method of an interpenetrating phase ceramic dental material, comprising the following steps:

[0009] Step one, based on three-dimensional modeling software, a bionic bird bone mortise and tenon structure is established, the bionic bird bone mortise and tenon structure comprises two bionic bird bone structures, the two different bionic bird bone structures are connected with each other in a mortise and tenon manner to form a model of the bionic bird bone mortise and tenon structure;

[0010] Step two, the bionic bird bone mortise and tenon structure designed in step one is imported into a model slicing software to perform model slicing, and the bionic bird bone mortise and tenon structure is printed and formed by using zirconia slurry based on light curing technology, and then defatting and sintering are performed, so as to obtain a bionic bird bone mortise and tenon structure with zirconia ceramic as a substrate;

[0011] Step three, the bionic bird bone mortise and tenon structure with zirconia ceramic as a substrate is prepared into a zirconia-hydrogel interpenetrating phase structure by using an in-situ light crosslinking method;

[0012] Step four, a multi-functional composite coating is added to the zirconia-hydrogel interpenetrating phase structure obtained in step three by using a sol-gel dip coating method, so as to prepare a multi-level zirconia-hydrogel bionic bird bone structure.

[0013] Further, the bionic bird bone structure comprises an R-type bionic bird bone structure and a Y-type bionic bird bone structure.

[0014] Further, the establishment method of the R-type bionic bird bone structure is as follows:

[0015] First, an equilateral triangle is drawn based on a front reference surface, and then the equilateral triangle is stretched to obtain a triangular prism structure with a length greater than the side length of the equilateral triangle, the surfaces where the two equilateral triangles of the triangular prism are located are defined as a top surface and a bottom surface, the surface where the quadrilateral is located is defined as a side surface, and any two long sides of the triangular prism are taken as reference axes 1 and reference axes 2, a vertical line of the reference axes 2 and the bottom side is drawn on the top surface, and a reference surface 0 is constructed based on the vertical line and the reference axes 2.

[0016] Draw a circle with a diameter less than or equal to the length of the edge of the equilateral triangle on the side of the triangular prism, and the circle is a certain distance from the top or bottom surface of the triangular prism, select the circle and perform a rotation cut based on the reference axis 1, get a ring-shaped cut feature connecting two sides in the triangular prism, then mirror the ring-shaped cut feature based on the reference surface 0 to get a cut feature connecting three sides, finally array the cut feature along the long edge direction of the triangular prism multiple times and cut it, finally get a triangular prism with multiple three-face interconnected openings;

[0017] After the opening, the triangular prism is bent twice. The first bending operation is a twisting operation with a twisting angle of 360 degrees, which twists the whole triangular prism once. The second bending operation is a bending operation, which connects the twisted triangular prism head to tail to form a ring;

[0018] Place the ring structure horizontally, offset a certain distance from the right view reference surface as the basis to the ring structure to make reference surface 1, offset a certain distance from the upper view reference surface as the basis to the ring structure to make reference surface 2, then mirror the ring structure once based on reference surface 1, and finally mirror the mirrored structure again based on reference surface 2, to finally get an R-type bionic bird bone structure monomer;

[0019] Define that the reference surface 1 is parallel to the plane formed by the Y axis and the Z axis, and the reference surface 2 is parallel to the plane formed by the X axis and the Y axis. Construct a coordinate system based on the two reference surfaces, array the R-type bionic bird bone structure monomer along the Y axis three times first, then array the arrayed structure along the Z axis again three times, a total of nine R-type bionic bird bone structure monomers, and finally get an R-type bionic bird bone structure.

[0020] Further, the establishment method of the Y-type bionic bird bone structure is as follows:

[0021] Based on the front view reference surface, a square sketch with a length of f and a height of g is established. The midpoint of the top of the square sketch and the endpoint of the left bottom are taken, and a spline curve is created between the two points. The two endpoints are named A and C, and the midpoint of the spline curve is named B. The angle of the vertex A and C along the tangent radial direction is-27.5, and the curvature radius size at the vertex is f / 2. The angle of the vertex B along the tangent radial direction is-55, and the curvature radius size is set to f+g. The corresponding spline curve is obtained, and then the spline curve is mirrored based on the straight line passing through the center point and point A of the square sketch to obtain the projection reference;

[0022] Then draw the projection path, which is drawn based on the left view reference surface. The projection path takes the upper and lower vertices of the square sketch as endpoints to construct a circular arc with a radius of r1;

[0023] Project the projection reference to the projection path to obtain a projection curve bending on the left view reference plane, and then scan the projection curve with a circular contour with a diameter of D1 to obtain the solid structure;

[0024] Determine the direction of the length f in the square sketch as the X axis, determine the height g direction as the Z axis, and the direction perpendicular to the X axis and the Z axis is the Y axis. Array the solid structure along the Z axis direction five times with an array distance of g / 2, array the solid structure after arraying along the X axis direction five times with an array distance of f, and finally mirror the solid structure after arraying along the front view reference plane to obtain a Y-shaped bionic bird bone structure monomer;

[0025] Array the Y-shaped bionic bird bone structure monomer along the Y axis direction three times to obtain a Y-shaped bionic bird bone structure, which includes three Y-shaped bionic bird bone structure monomers in total.

[0026] Further, the size and aspect ratio of the two bionic bird bone structure sections in step one are the same.

[0027] Further, the zirconium oxide slurry formula in step two is as follows:

[0028] Mix 85wt% of 3Y-TZP zirconium oxide powder with 4.5wt% of HDDA, 3.0wt% of PEG400DA, 0.5wt% of a photoinitiator, and 2.0wt% of a dispersant, and stir the mixture in a planetary centrifugal mixer at 2000rpm for 40 minutes under vacuum to obtain a uniform and stable slurry with a solid content of 52vol%.

[0029] Further, the light curing printing parameters in step two are as follows:

[0030] The printing is performed with the following parameters: single layer exposure time of 6 seconds, bottom layer exposure time of 35 seconds, single layer thickness of 50μm, and light source intensity of 15mW / cm²;

[0031] After the printed green body is cleaned by ultrasonic and dried, programmed debinding and sintering are performed, and finally a zirconium oxide ceramic as a matrix bionic bird bone mortise and tenon structure is obtained.

[0032] Further, the debinding and sintering in step two are as follows:

[0033] The debinding process is performed in an air atmosphere, and the specific steps are as follows:

[0034] Ramp up to 200℃ at 1℃ / min and hold for 30 minutes, then ramp up to 500℃ at 0.5℃ / min and hold for 120 minutes, and finally ramp up to 600℃ at 1℃ / min and hold for 60 minutes, and then cool down with the furnace;

[0035] After defatting, the ceramic body is placed in a high-temperature sintering furnace and sintered in an air atmosphere. The specific steps are as follows:

[0036] Ramp up to 1000℃ at 5℃ / min, no holding, then ramp up to the final sintering temperature of 1500℃ at 2℃ / min, and hold at this temperature for 120 minutes to achieve complete densification, finally control cooling to below 1000℃ at a rate of 3℃ / min, then furnace cooling to room temperature, finally get zirconia ceramic as the matrix of biomimetic bird bone mortise and tenon structure.

[0037] Further, the specific preparation steps of the in-situ photocrosslinking method for preparing zirconia-hydrogel interpenetrating phase structure in step three are as follows:

[0038] Dissolve the solid powder of methacrylated gelatin and the solid powder of the photoinitiator Irgacure 2959 in phosphate buffer as the only solvent, and make the two solutes into a solution with a concentration of 15% w / v and 0.5% w / v respectively. Stir in a 60℃ water bath until the two solutes are completely dissolved, then remove the bubbles at 4℃ environment and prepare as precursor solution for standby;

[0039] After the zirconia ceramic as the matrix of biomimetic bird bone mortise and tenon structure obtained in step two is treated by oxygen plasma, it is completely immersed in the precursor solution and kept for 30 minutes in a vacuum environment of-0.1MPa for impregnation;

[0040] After impregnation, the sample is transferred to 365nm ultraviolet light, and irradiated for 75 seconds in a nitrogen atmosphere at a light intensity of 8mW / cm², so that the methacrylated gelatin is in-situ photopolymerized inside the biomimetic bird bone mortise and tenon structure to form a stable zirconia-hydrogel interpenetrating phase structure.

[0041] Further, the specific method of preparing a multi-level zirconia-hydrogel biomimetic bird bone structure by sol-gel dip coating in step four is as follows:

[0042] Sol preparation: mix tetraethyl orthosilicate, ethanol, water and catalyst in a certain proportion, hydrolyze under a certain temperature and stir to form a stable SiO2 sol;

[0043] Dip coating: completely immerse the zirconia-hydrogel interpenetrating phase structure into the prepared sol and keep for a period of time to ensure sufficient wetting of the inner and outer surfaces;

[0044] Pulling: pull the zirconia-hydrogel interpenetrating phase structure out of the sol at a constant and slow speed to form a uniform liquid film on its surface;

[0045] Heat treatment: the zirconia-hydrogel interpenetrating phase structure after pulling is dried at 50-100℃, then heat treated at 400-600℃, so that the solvent volatilizes and the organic matter decomposes, and finally an amorphous, dense SiO2-based glass-ceramic coating is formed on the surface of the zirconia-hydrogel interpenetrating phase structure. Compared with the prior art, the beneficial effects of the present application are:

[0046] Inspired by the biological composite materials in nature such as bird skeletons, two types of biomimetic bird head structures combining the cavity tissue of bird head and the characteristics of the ring-shaped hyoid bone are designed, and the two types of head structures are dovetailed into a biomimetic bird dovetail structure, which imitates the synergistic mechanism of vibration reduction of bird skeletons, and realizes lightweight, high toughness and high energy dissipation compared with traditional support forms.

[0047] By introducing a hydrogel phase to form a three-dimensional interpenetrating structure, multiple toughening mechanisms can be achieved: when the main crack propagates in the zirconia skeleton, the flexible hydrogel network absorbs energy through its huge viscoelastic deformation, and effectively transmits and disperses stress through the two-phase interface, inducing crack deflection, bridging and even pinning, thereby significantly blunting the crack tip and inhibiting its unstable propagation. This comprehensive improvement in toughness can significantly reduce the risk of porcelain collapse and fracture of the restoration due to fatigue load or accidental impact in clinical use, and improve the long-term safety and durability of the restoration structure such as crown and bridge.

[0048] A sol-gel dip coating technique is used to immerse the interpenetrating phase composite material in a composite sol with tetraethyl orthosilicate and butyl titanate as precursors, and after uniform pulling and programmed heat treatment (maximum temperature 600℃), a dense SiO2-TiO2 hybrid glass coating with a thickness of about 200 nanometers is formed on the surface. The coating not only effectively seals the surface micro-defects, but also endows the material with excellent acid erosion resistance due to its inherent chemical inertness. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 Schematic diagram of two types of biomimetic bird bone structures designed based on different microfeatures of bird head bones and hyoid bones;

[0050] Figure 2 Schematic diagram of the R-type biomimetic bird bone structure designed in the present application;

[0051] Figure 3 Schematic diagram of the Y-type biomimetic bird bone structure designed in the present application;

[0052] Figure 4 Schematic diagram of the biomimetic bird dovetail structure designed in the present application;

[0053] Figure 5 Schematic diagram of the preparation of zirconia-hydrogel interpenetrating phase structure based on in-situ photo-crosslinking method;

[0054] Figure 6 Schematic diagram of the preparation of a multilevel zirconia-hydrogel biomimetic bird bone structure for sol-gel dip-coating technology;

[0055] Figure 7 Effect display diagram of the multilevel zirconia-hydrogel biomimetic bird bone structure;

[0056] In the figure: 11, R-type biomimetic bird bone structure; 110, R-type biomimetic bird bone structure monomer, 12, Y-type biomimetic bird bone structure; 120, Y-type biomimetic bird bone structure monomer; 2, biomimetic bird bone mortise and tenon structure; 3, zirconia-hydrogel interpenetrating phase structure; 4, multilevel zirconia-hydrogel biomimetic bird bone structure. DETAILED DESCRIPTION

[0057] The application will be further described below in combination with specific embodiments.

[0058] The present scheme is based on the biomimetic design of the woodpecker bone microstructure in nature. As shown in Figure 1 , the head bone of the woodpecker, especially the forehead area, presents a highly developed porous foam-like structure. This specialized super-porous structure is like an efficient "natural energy absorption box" located between the beak root and the brain. When impact is borne, the structure absorbs and disperses energy through the collapse and plastic deformation of a large number of micro-pores inside, thereby effectively protecting the brain.

[0059] And the hyoid bone structure of the woodpecker is particularly developed, which does not simply surround, but originates from the back of the lower jaw, extends upward and backward in two ways, passes above the nostrils, and finally converges at the forehead to form a ring-shaped support system covering the entire skull. The entire hyoid bone is like an "in-built safety helmet framework", which fully encloses the brain. This unique path enables it to effectively dampen the skull from multiple directions. Whether the impact is mainly from the front or other directions, the hyoid bone system can be activated and involved in overall vibration reduction, showing excellent multidirectional protection and collaborative buffering capacity.

[0060] As shown in Figure 1 , the head bone cavity features and the hyoid ring characteristics present in the woodpecker bone system are extracted and integrated into the biomimetic framework, based on which two biomimetic bird bone structures are designed, including an R-type biomimetic bird bone structure 11, which is abbreviated as BBSTR (Bionic-bird bone structure type R), and a Y-type biomimetic bird bone structure 12, which is abbreviated as BBSTY (Bionic-bird bone structure type Y).

[0061] As shown in Figure 2As shown, the function commands used in the embodiment are selected from the commands in the software soildworks. When other modeling software is selected, the model can be constructed according to the commands with the same function. The design steps of the R-type bionic bird bone structure 11 are as follows:

[0062] First, the commands of stretching, cutting, mirroring and arraying are respectively performed to complete the establishment of the right triangular prism with circular holes.

[0063] The establishment method of the right triangular prism with circular holes is as follows: taking the front reference plane as the reference, an equilateral triangle with a side length of a is drawn at the default origin, and a solid stretching operation is performed based on this, and the stretching length is b, which is much larger than the side length a of the equilateral triangle. The two faces where the equilateral triangles of the triangular prism are located are defined as the top face and the bottom face, and the face where the quadrilateral is located is defined as the side face. At the same time, two edge lines of the right triangular prism are taken to construct reference axes 1 and 2. The perpendicular line of the reference axis 2 and the bottom edge is made on the top face, and the reference plane 0 is constructed based on the perpendicular line and the reference axis 2.

[0064] Then, the cutting command is performed on the upper reference plane. A circle with a diameter of d is drawn on the side face of the triangular prism, and the diameter of the circle is less than the side length of the equilateral triangle. The circle is at a certain distance from the top face or the bottom face of the triangular prism. The circle is selected to perform the rotation cutting command with the reference axis 1 as the reference to complete the preliminary modeling of the hole. Then, the ring-shaped cutting feature is mirrored based on the reference plane 0 to obtain a cutting feature connected to three side faces. This command ensures that the three faces of the triangular prism have holes. Then, taking the front reference plane as the reference, the feature arraying is performed to array the three holes with an instance number of seven to complete the establishment of the reference model.

[0065] After the reference model is established, two bending operation commands are performed. In the first solid bending, the twist operation is selected, and the twist angle is selected as 360 degrees. In the second solid bending, the bending operation is selected, the angle is selected as 359.5 degrees, the bending radius is selected as 55.78 mm, and the reference triple axes are defined as 0, 0 and 90 degrees. At this time, the preliminary monomer (i.e. the ring-shaped structure) is constructed. Then, the preliminary monomer is rounded. The rounded corners can relieve the stress concentration trend under load compared with sharp corners. Taking the right reference plane and the upper reference plane as the reference, reference planes 1 and 2 are respectively constructed at positions parallel to the right reference plane and the upper reference plane near the ring-shaped structure with distances of d and e. In this embodiment, the reference plane 1 is defined to be parallel to the plane formed by the Y axis and the Z axis, and the reference plane 2 is defined to be parallel to the plane formed by the X axis and the Y axis. The coordinate system is constructed based on the two reference planes.

[0066] Then, the annular structure is respectively subjected to entity mirroring commands with the reference surface 1 and the reference surface 2 to obtain the R-type bionic bird bone structure monomer 110 with the size of X1xY1xZ1. Finally, the R-type bionic bird bone structure monomer 110 is arrayed along the Y axis three times with an array distance of Y1, and then the arrayed structure is arrayed along the Z axis three times with an array distance of Z1. The arrayed structure finally contains nine R-type bionic bird bone structure monomers 110, and the final combined entity obtains the R-type bionic bird bone structure 11.

[0067] As shown in the figure, the design steps of the Y-type bionic bird bone structure 12 are as follows: Figure 3

[0068] A first curve is drawn as a projection reference: a square sketch with a length of f and a height of g is established with the front view reference surface as a reference, and a spline curve is drawn on the square sketch, passing through three points A, B, and C in the figure, wherein A is the midpoint of the top of the square sketch, C is the endpoint of the left side of the bottom of the square sketch, and B is the intermediate point. The angles of the upper and lower vertices A and C of the spline curve along the tangent radial direction are both set to -27.5, the curvature radius sizes at the vertices A and C are both set to f / 2, the angle of the intermediate vertex B along the tangent radial direction is set to -55, and the curvature radius size is set to f+g. Then, the spline curve is mirrored with the straight line passing through the center point and the point A of the square sketch as a reference to obtain the projection reference.

[0069] Then, a second curve is drawn as a projection path: the projection path is drawn on the left view reference surface, and a circular arc with a radius of r1 is constructed passing through the upper and lower vertices of the square sketch.

[0070] Subsequently, the two curves are selected for a projection curve command, the second curve is selected as the projection path, and then the first curve is selected as the projection reference sketch contour. After the projection is completed, the projection curve is obtained, that is, the projection reference is curved on the projection path. In this embodiment, the length f direction in the square sketch is determined as the X axis, the height g direction is determined as the Z axis, and the direction perpendicular to the X axis and the Z axis is the Y axis.

[0071] Then, a scanning command is performed on the projection curve, and the scanning contour is a circular contour with a diameter of D1 to obtain the entity structure.

[0072] The entity structure is arrayed along the Z axis direction five times with an array distance of g / 2, and the arrayed entity structure is arrayed along the X axis direction five times with an array distance of f. Subsequently, the arrayed linear entity is subjected to a mirroring command with the front view reference surface to form the Y-type bionic bird bone structure monomer 120 with the size of X2xY2xZ2. Finally, the Y-type bionic bird bone structure monomer 120 is arrayed along the Y axis direction three times with an array distance of Y2 to form the Y-type bionic bird bone structure 12.

[0073] ​The hyoid bone of the woodpecker forms a complete ring, nesting the core area of the skull therein. This is similar to a ring-shaped, closed "cuff" or "frame", which forms a nested mortise-and-tenon system with the skull. This structure greatly enhances the overall stability of the system, preventing instability and dislocation of the parts under impact, and ensuring the reliability and controllability of the energy transmission path.

[0074] Based on the woodpecker bone mortise-and-tenon system, the structure is further optimized, as shown in Figure 4 The R-type bionic bird bone structure 11 and the Y-type bionic bird bone structure 12 are scaled, respectively, to the size of X3×Y3×Z3, ensuring that their sizes are consistent, and then the mortise-and-tenon connection is performed. The edge part scanned out of the Y-type bionic bird bone structure 12 is inserted into the hole of the R-type bionic bird bone structure 11, forming a bionic bird bone mortise-and-tenon structure 2 with the R-type bionic bird bone structure 11 and the Y-type bionic bird bone structure 12, which is abbreviated as BBMS (Bionic-bird bone mortise-and-tenon structure). In this embodiment, the bionic bird bone mortise-and-tenon structure 2 is composed of 3 R-type bionic bird bone structures 11 and 3 Y-type bionic bird bone structures 12, Figure 4 The BBMS in the figure is the final assembled schematic diagram. The bionic bird bone mortise-and-tenon structure 2 can achieve the effect of cooperative vibration reduction when facing impact in different directions.

[0075] After designing the model of the bionic bird bone mortise-and-tenon structure 2, the interpenetrating phase ceramic material based on the structure can be manufactured. The specific preparation method is as follows:

[0076] Step one: based on a three-dimensional modeling software, the model of the bionic bird bone mortise-and-tenon structure 2 is established. The bionic bird bone mortise-and-tenon structure 2 includes the R-type bionic bird bone structure 11 and the Y-type bionic bird bone structure 12. Then the model is appropriately scaled to ensure that the sizes of the R-type bionic bird bone structure 11 and the Y-type bionic bird bone structure 12 are consistent. Then the mortise-and-tenon connection is completed by using the assembly body cooperation command, and finally the model of the bionic bird bone mortise-and-tenon structure 2 is obtained.

[0077] Step two: the model of the bionic bird bone mortise-and-tenon structure 2 designed in step one is converted into a Stl format file and imported into Lychee Slicer slicing software. Based on the Digital Light Processing (DLP) technology, the bionic bird bone mortise-and-tenon structure 2 is printed using zirconia slurry. Then, defatting and sintering are performed, and the zirconia ceramic is obtained as the matrix of the bionic bird bone mortise-and-tenon structure 2.

[0078] Step three: the biomimetic bird bone mortise-tenon structure 2 with zirconia ceramic as the matrix is prepared into zirconia-water gel interpenetrating phase structures 3 (ZGIPS) by using the method of in-situ photo-crosslinking.

[0079] Step four: the multifunctional composite coating is added to the zirconia-water gel interpenetrating phase structures 3 obtained in step three by using the method of sol-gel dip coating, and the zirconia-water gel biomimetic bird bone structure 4 (MZGBBS) is prepared.

[0080] The zirconia slurry in step two is prepared as follows: 85wt% of 3Y-TZP zirconia powder is mixed with 4.5wt% of HDDA, 3.0wt% of PEG400DA, 0.5wt% of BAPO photoinitiator and 2.0wt% of Hypermer KD-4 dispersant, and then stirred in a planetary centrifugal mixer at 2000rpm for 40 minutes under vacuum to obtain a uniform and stable slurry with a solid content of 52vol%.

[0081] The DLP printing parameters in step two are as follows: the printing is performed with the parameters of single-layer exposure time of 6 seconds, bottom layer exposure time of 35 seconds, single-layer thickness of 50μm, and light source intensity of 15mW / cm². After the green body is cleaned by ultrasonic and dried, the programmed debinding and sintering are performed, and finally the biomimetic bird bone mortise-tenon structure 2 with zirconia ceramic as the matrix is obtained.

[0082] The debinding and sintering processes in step two are as follows:

[0083] The debinding process is performed in an air atmosphere, and the specific steps are as follows: heating to 200℃ at a rate of 1℃ / min and keeping for 30 minutes, then heating to 500℃ at a rate of 0.5℃ / min and keeping for 120 minutes, finally heating to 600℃ at a rate of 1℃ / min and keeping for 60 minutes, and then cooling with the furnace.

[0084] After debinding, the ceramic blank is placed in a high-temperature sintering furnace and sintered in an air atmosphere, and the specific steps are as follows: heating to 1000℃ at a rate of 5℃ / min without keeping; then heating to the final sintering temperature of 1500℃ at a rate of 2℃ / min and keeping for 120 minutes to achieve complete densification; finally, cooling to below 1000℃ at a rate of 3℃ / min, and then cooling with the furnace to room temperature, and finally obtaining the biomimetic bird bone mortise-tenon structure 2 with zirconia ceramic as the matrix.

[0085] The forming effect of the zirconia-hydrogel interpenetrating phase structure 3 prepared by in-situ photocrosslinking method in step three is shown in Figure 5 The left side of the figure is a perspective structural diagram of the zirconia-hydrogel interpenetrating phase structure 3, and the right side is the actual morphology diagram of the R-type and Y-type biomimetic bird bone structures 11 and 12 after the in-situ photocrosslinking method is completed, and the specific preparation steps are as follows:

[0086] First, the precursor solution is configured for standby. The configuration method of the precursor solution is as follows: taking phosphate buffered saline (PBS) as the only solvent, dissolving solid powdery methacrylated gelatin (GelMA) and solid powdery photoinitiator Irgacure 2959 at the same time, and the two solutes should reach 15% w / v concentration and 0.5% w / v concentration (i.e. 100 mL of buffer solution is added with 15 g of GelMA and 0.5 g of Irgacure 2959) after being configured into a solution. Stir in a 60°C water bath until the two solutes are completely dissolved, and then place in a 4°C environment to remove bubbles for standby.

[0087] After the biomimetic bird bone mortise and tenon structure 2 with zirconia ceramic as the substrate is treated by oxygen plasma, it is completely immersed in the precursor solution and kept in a vacuum environment of -0.1 MPa for 30 minutes to achieve sufficient infiltration. Then, the sample is transferred to 365 nm ultraviolet light, and irradiated under a nitrogen atmosphere with a light intensity of 8 mW / cm² for 75 seconds to make the methacrylated gelatin in-situ photopolymerize inside the biomimetic bird bone mortise and tenon structure 2, forming a stable zirconia-hydrogel interpenetrating phase structure 3.

[0088] The forming effect of the multilevel zirconia-hydrogel biomimetic bird bone structure 4 prepared by sol-gel dip coating is shown in Figure 6 The specific steps include sol preparation, dip coating, pulling and heat treatment.

[0089] Sol preparation: mix tetraethyl orthosilicate (TEOS), ethanol, water and catalyst (such as HCl) in a certain proportion, hydrolyze under a certain temperature and stir to form a stable SiO2 sol. To improve toughness, a small amount of butyl titanate can be added to form a SiO2-TiO2 composite sol.

[0090] Dip coating: completely immerse the zirconia-hydrogel interpenetrating phase structure 3 in the prepared sol and keep it for a period of time to ensure that the inner and outer surfaces are fully infiltrated.

[0091] Pulling: pull the zirconia-hydrogel interpenetrating phase structure 3 out of the sol at a constant and slow speed to form a uniform liquid film on its surface.

[0092] Heat treatment: first dry at low temperature (50~100℃), then heat treatment at higher temperature (400-600℃), so that the solvent volatilizes and the organic matter decomposes, and finally an amorphous and dense SiO2-based glass-ceramic coating is formed on the surface of the zirconia-hydrogel interpenetrating phase structure 3.

[0093] The effects of the present application are shown in Figure 7 Firstly, the traditional zirconia bracket design often faces the risk of failure and damage, while the bionic bird bone mortise and tenon structure 2 prepared by the present application can realize the effect of cooperative vibration reduction when facing impact in different directions, and the structure corners after rounding treatment are less likely to appear stress concentration risk compared with the sharp corners of traditional structure, so the carrying capacity is more excellent and the deformation mode is more stable.

[0094] Secondly, the toughening mechanism of traditional zirconia ceramic mainly depends on phase change toughening, which has the risk of aging in the later service stage and limited ability to inhibit crack propagation. The zirconia-hydrogel interpenetrating phase structure 3 prepared by introducing hydrogel phase can realize multiple toughening mechanisms: when the main crack propagates in the zirconia skeleton, the flexible hydrogel network absorbs energy through its huge viscoelastic deformation, and effectively transmits and disperses stress through the two-phase interface, inducing crack deflection, bridging and even pinning, thereby significantly blunting the crack tip and inhibiting its unstable propagation.

[0095] In addition, the partially stabilized zirconia ceramic material using yttrium oxide as a stabilizer in the prior art has a long-term "low temperature aging" phenomenon in the oral warm and humid environment. The multilevel zirconia-hydrogel bionic bird bone structure 4 prepared by sol-gel dip coating technology forms a dense SiO2-TiO2 hybrid glass coating layer with a thickness of about 200 nanometers on the surface of the zirconia-hydrogel interpenetrating phase structure 3. This coating not only effectively seals the surface micro defects, but also its inherent chemical inertness gives the material excellent acid erosion resistance.

Claims

1. A method for preparing an interpenetrating phase ceramic dental material, characterized in that, Includes the following steps: Step 1: Based on 3D modeling software, complete the establishment of the biomimetic bird bone mortise and tenon structure. The biomimetic bird bone mortise and tenon structure includes two biomimetic bird bone structures. The two different biomimetic bird bone structures are connected to each other by mortise and tenon to form the model of the biomimetic bird bone mortise and tenon structure. Step 2: Import the biomimetic bird bone tenon structure designed in Step 1 into the model slicing software for model slicing. Based on photopolymerization technology, use zirconia slurry to print the biomimetic bird bone tenon structure. Then, degrease and sinter it to obtain a biomimetic bird bone tenon structure with zirconia ceramic as the matrix. Step 3: The biomimetic bird bone tenon structure with zirconia ceramic as the matrix is ​​prepared into a zirconia-hydrogel interpenetrating phase structure by in-situ photocrosslinking. Step four: Using a sol-gel dip-coating method, a multifunctional composite coating is added to the zirconia-hydrogel interpenetrating phase structure obtained in step three to prepare a multi-layered zirconia-hydrogel biomimetic bird bone structure. The specific method for preparing the multi-layered zirconia-hydrogel biomimetic bird bone structure using sol-gel dip coating in step four is as follows: Sol preparation: Tetraethyl orthosilicate, ethanol, water and catalyst are mixed in a certain proportion and stirred and hydrolyzed at a certain temperature to form a stable SiO2 sol; Dip coating: The zirconium oxide-hydrogel interpenetrating phase structure is completely immersed in the prepared sol and kept for a period of time to ensure that the inner and outer surfaces are fully wetted; Soluble extraction: The zirconia-hydrogel interpenetrating phase structure is extracted from the sol at a constant and slow speed to form a uniform liquid film on its surface; Heat treatment: First, the zirconium oxide-hydrogel interpenetrating phase structure after pulling is dried at 50-100℃, and then heat-treated at 400-600℃ to evaporate the solvent and decompose the organic matter, and finally form an amorphous, dense SiO2-based glass ceramic coating on the surface of the zirconium oxide-hydrogel interpenetrating phase structure.

2. The method for preparing an interpenetrating phase ceramic dental material according to claim 1, characterized in that, The biomimetic bird bone structure includes an R-type biomimetic bird bone structure and a Y-type biomimetic bird bone structure.

3. The method for preparing an interpenetrating phase ceramic dental material according to claim 2, characterized in that, The method for establishing the R-type bionic bird bone structure is as follows: First, draw an equilateral triangle based on the front reference plane. Then, extrude the equilateral triangle to obtain a triangular prism structure with a length greater than the side length of the equilateral triangle. The faces containing the two equilateral triangles of the triangular prism are defined as the top face and the bottom face, and the face containing the quadrilateral is defined as the side face. Take any two long sides of the triangular prism as reference axis 1 and reference axis 2. Draw a perpendicular line between reference axis 2 and the bottom side on the top face. Based on the perpendicular line and reference axis 2, construct reference plane 0. Draw a circle with a diameter smaller than the side length of an equilateral triangle on the side of the triangular prism, and the circle is a certain distance away from the top or bottom surface of the triangular prism. Select the circle and perform a rotation cut based on the reference axis 1 to obtain a ring cut feature connecting two sides inside the triangular prism. Then, mirror the ring cut feature based on the reference plane 0 to obtain a cut feature connecting three sides. Finally, array the cut feature multiple times along the long side of the triangular prism and perform cuts to obtain a triangular prism with multiple three-sided interconnected openings. The triangular prism after the hole is made is bent twice. The first bending operation is a twisting operation with a twisting angle of 360 degrees, and the entire triangular prism is twisted once. The second bending operation is a bending operation, and the twisted triangular prism is connected end to end to form a ring. Place the ring structure horizontally, and use the right-view reference plane as the reference plane offset by a certain distance towards the ring structure to form reference plane 1, and the top-view reference plane as the reference plane offset by a certain distance towards the ring structure to form reference plane 2. Then, mirror the ring structure once based on reference plane 1. Finally, mirror the mirrored structure once again based on reference plane 2 to obtain the R-shaped bionic bird bone structure unit. Define reference plane 1 as parallel to the plane formed by the Y-axis and Z-axis, and reference plane 2 as parallel to the plane formed by the X-axis and Y-axis. Construct a coordinate system based on the two reference planes. First, array the R-type bionic bird bone structure unit three times along the Y-axis, and then array the structure three times again along the Z-axis. A total of nine R-type bionic bird bone structure units are included, and finally the R-type bionic bird bone structure is obtained.

4. The method for preparing an interpenetrating phase ceramic dental material according to claim 2, characterized in that, The method for establishing the Y-shaped bionic bird bone structure is as follows: Create a square sketch of length f and height g based on the front reference plane. Take the midpoint of the top and the endpoint of the bottom left of the square sketch and create a spline curve between the two points. Name the two endpoints A and C, and name the midpoint of the spline curve B. The angles of the spline curve vertices A and C along the tangent radial direction are both -27.5 degrees, and the radius of curvature at the vertices is f / 2. The angle of point B along the tangent radial direction is -55 degrees, and the radius of curvature is set to f+g. The corresponding spline curve is obtained. Then, the spline curve is mirrored with the straight line of the square sketch passing through the center point and point A as the reference to obtain the projection reference. Then draw the projection path. The projection path is drawn based on the left view reference plane. The projection path uses the top and bottom vertices of the square sketch as endpoints to construct an arc with a radius of r1. The projection reference is projected onto the projection path to obtain a projection curve that curves on the left view reference plane. Then, the projection curve is scanned with a circular outline of diameter D1 to obtain the solid structure. The X-axis is defined by the length f in the square sketch, the Z-axis by the height g, and the Y-axis by the direction perpendicular to both the X-axis and the Z-axis. The solid structure is arrayed five times along the Z-axis with an array distance of g / 2. The arrayed solid structure is then arrayed five times along the X-axis with an array distance of f. Finally, the arrayed solid structure is mirrored along the front reference plane to obtain the Y-shaped bionic bird bone structure unit. The Y-shaped bionic bird bone structure units are arranged three times along the Y-axis, resulting in a total of three Y-shaped bionic bird bone structure units, thus obtaining the Y-shaped bionic bird bone structure.

5. The method for preparing an interpenetrating phase ceramic dental material according to claim 1, characterized in that, The two biomimetic bird bone structures in step one have the same cross-sectional dimensions and aspect ratios.

6. The method for preparing an interpenetrating phase ceramic dental material according to claim 1, characterized in that, The photopolymerization printing parameters in step two are as follows: The printing was performed using parameters of 6 seconds for single-layer exposure, 35 seconds for bottom layer exposure, 50μm for single-layer thickness, and 15mW / cm² light intensity. After ultrasonic cleaning and drying, the printed green body undergoes programmed degreasing and sintering to finally obtain a biomimetic bird bone tenon and mortise structure with zirconia ceramic as the matrix.

7. The method for preparing an interpenetrating phase ceramic dental material according to claim 1, characterized in that, The specific steps of degreasing and sintering in step two are as follows: The degreasing process is carried out in an air atmosphere, and the specific steps are as follows: The temperature was increased to 200℃ at 1℃ / min and held for 30 minutes, then increased to 500℃ at 0.5℃ / min and held for 120 minutes, and finally increased to 600℃ at 1℃ / min and held for 60 minutes, and then cooled in the furnace. The degreased ceramic blanks are placed in a high-temperature sintering furnace and sintered in air atmosphere. The specific steps are as follows: The temperature was increased to 1000℃ at 5℃ / min without holding, and then increased to the final sintering temperature of 1500℃ at 2℃ / min. The temperature was held at this temperature for 120 minutes to achieve complete densification. Finally, the temperature was controlled to be cooled to below 1000℃ at a rate of 3℃ / min, and then cooled to room temperature in the furnace. The result was a biomimetic bird bone tenon structure with zirconia ceramic as the matrix.

8. The method for preparing an interpenetrating phase ceramic dental material according to claim 1, characterized in that, The specific preparation steps for the in-situ photocrosslinking method to prepare the zirconia-hydrogel interpenetrating phase structure in step three are as follows: Using phosphate buffer as the sole solvent, solid powdered methacrylamide gelatin and solid powdered photoinitiator Irgacure 2959 were dissolved to achieve a concentration of 15% w / v and 0.5% w / v respectively. The solutions were stirred in a 60°C water bath until both solutes were completely dissolved, and then placed at 4°C to remove bubbles before use as precursor solutions. The biomimetic bird bone tenon structure with zirconia ceramic as the matrix obtained in step two was treated with oxygen plasma, then completely immersed in the precursor solution, and impregnated for 30 minutes under a vacuum of -0.1 MPa. After impregnation, the sample was transferred to 365nm ultraviolet light and irradiated for 75 seconds in a nitrogen atmosphere with a light intensity of 8mW / cm², so that the methacrylamide gelatin was photopolymerized in situ inside the biomimetic bird bone tenon and mortise structure to form a stable zirconium oxide-hydrogel interpenetrating phase structure.

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