Dental restoration material and preparation method thereof

Abstract

The invention belongs to a material preparation method, and provides a dental restoration material and a preparation method thereof in order to solve the technical problem that a dental restoration material composed of zirconia ceramic and lithium disilicate glass ceramic at present is still poor in performance and cannot meet clinical use requirements. The nano zirconium oxide particles are uniformly added into the silicon oxide glass matrix, so that the mechanical property can be ensured, and meanwhile, the adhesive property of zirconium oxide can be effectively improved. Meanwhile, the uniformity of the molecular level can be obtained in a short time by the sol-gel method, the uniform nano silicon oxide / zirconium oxide composite powder is prepared, the material can be sintered at high pressure and low temperature by the cold sintering technology, the grain size can be controlled at the nanoscale, and the mechanical property of the material is ensured. The prepared nano-zirconia reinforced silica glass ceramic has the comprehensive excellent performance of high strength, elasticity modulus and hardness close to those of tooth enamel, and good adhesion with teeth.

Description

Technical Field

[0001] This application belongs to a method for preparing materials, and particularly relates to a dental restoration material and a preparation method thereof. Background Art

[0002] Tooth defects and tooth loss have varying degrees of impact on people's chewing, pronunciation, aesthetics, and even overall health. It is crucial to use artificial materials for restoration to promptly restore the shape and function of the defective or missing teeth. Currently, the dental restoration materials widely used clinically are mainly zirconia ceramics and lithium disilicate glass ceramics. The surface treatment methods for improving the bonding performance of zirconia are mainly divided into physical and chemical methods, but they still cannot meet the clinical use requirements. At the same time, for zirconia ceramics, introducing the glass phase silica to improve the bonding performance will cause a decrease in the mechanical properties of zirconia ceramics. Therefore, the performance of the current dental restoration materials composed of zirconia ceramics and lithium disilicate glass ceramics is still poor. Summary of the Invention

[0003] This application aims at the technical problem that the performance of the current dental restoration materials composed of zirconia ceramics and lithium disilicate glass ceramics is still poor and cannot meet the clinical use requirements, and provides a dental restoration material and a preparation method thereof.

[0004] To achieve the above object, this application adopts the following technical solutions to be realized: In the first aspect, this application proposes a preparation method for a dental restoration material, including: Dissolve tetraethyl orthosilicate in a mixture of a first solvent and a first acidic solution to obtain solution A; Dissolve zirconium propoxide in a second solvent to obtain solution B; Mix solution A and solution B to obtain solution C; Add a second acidic solution to solution C to obtain solution D; Gelify solution D to obtain the corresponding xerogel; After grinding the xerogel and removing the residual organic matter, obtain a nano zirconia / silica composite powder; Prepare the nano zirconia / silica composite powder into nano zirconia-reinforced silica glass ceramics.

[0005] Further, by volume percentage, when preparing solution A and solution B: tetraethyl orthosilicate is 5 - 50 vol.%, and zirconium propoxide is 50 - 95 vol.%; The volume of the first solvent is 25 - 30% of that of tetraethyl orthosilicate, and the volume of the second solvent is 1.2 - 1.5 times that of zirconium propoxide.

[0006] Further, the added volume of the first acidic solution is 8-10% of tetraethyl orthosilicate, and the added volume of the second acidic solution is 7-10% of solution C.

[0007] Further, the purity of the tetraethyl orthosilicate is greater than 99.99%, and the concentration of zirconium propoxide is 70 wt%.

[0008] Further, the first solvent is anhydrous ethanol, the second solvent is isopropanol, the first acidic solution is dilute hydrochloric acid, and the second acidic solution is concentrated hydrochloric acid.

[0009] Further, the concentration of the dilute hydrochloric acid is 0.4 mol·L -1 , and the concentration of the concentrated hydrochloric acid is 37 wt%.

[0010] Further, preparing the nano-zirconia / silica composite powder into nano-zirconia-reinforced silica glass ceramics includes: Mixing the nano-zirconia / silica composite powder and deionized water; Performing cold sintering after mixing; wherein, when cold sintering, a load of 300-400 MPa is applied, the pressure is maintained for 10-30 min, the temperature is raised to 140-220 °C and kept warm for 0.5-3 h to obtain a green body; Heat-treating the green body at a temperature of 1100-1400 °C for 0.5-3 h to obtain nano-zirconia-reinforced silica glass ceramics.

[0011] Further, the heat-treating the green body at a temperature of 1100-1400 °C for 0.5-3 h includes heat-treating according to five stages: The first stage: raising the temperature to 200 °C at a heating rate of 10 °C·min -1 ; The second stage: keeping warm at 200 °C for 12 h; The third stage: raising the temperature from 200 °C to 900 °C at a heating rate of 5 °C·min -1 ; The fourth stage: keeping warm at 900 °C for 2 h; The fifth stage: raising the temperature from 900 °C to 1100-1400 °C at a heating rate of 2 °C·min -1 .

[0012] Further, when mixing the nano-zirconia / silica composite powder and deionized water, the mass ratio of the nano-zirconia / silica composite powder to deionized water is (60-80):(20-40); The heating rate of the cold sintering is 10 °C·min -1 .

[0013] In a second aspect, the present application provides a dental restoration material obtained by the preparation method using the above dental restoration material.

[0014] Compared with the prior art, the present application has the following beneficial effects: The present application provides a preparation method for a dental restoration material. By uniformly adding nano-zirconia particles into a silica glass matrix, the bonding performance of zirconia can be effectively improved while ensuring the mechanical properties. At the same time, the sol-gel method can achieve molecular-level uniformity in a short time to prepare a uniform nano-silica / zirconia composite powder. The cold sintering technology can sinter the material under high pressure and low temperature, and can control the grain size at the nanoscale, ensuring the mechanical properties of the material. The prepared nano-zirconia reinforced silica glass ceramic has high strength, an elastic modulus and hardness close to those of tooth enamel, and excellent comprehensive properties of good bonding with teeth, which will play a significant role in promoting the clinical durability of zirconia restorations and other aspects.

[0015] The present application also provides a dental restoration material, which has all the advantages of the above preparation method for a dental restoration material. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other relevant drawings can also be obtained based on these drawings.

[0017] Figure 1 It is a schematic diagram of the microstructure of the zirconia / silica composite powder obtained in Example 1; Figure 2 It is a schematic diagram of the microscopic morphology of the nano-silica / zirconia green body sintered by the cold sintering method in Example 1; Figure 3 It is a schematic diagram of the microscopic morphology of the nano-zirconia reinforced silica glass ceramic prepared in Example 1 of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Usually, the components of the embodiments of the present application described and illustrated in the drawings here can be arranged and designed in various different configurations.

[0019] Accordingly, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but merely represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the scope of protection of the present application.

[0020] It should be noted that like reference numerals and letters denote like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

[0021] In the description of the embodiments of the present application, it should be noted that if terms such as "upper", "lower", "horizontal", "inner", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is customarily placed during use. This is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application. In addition, terms such as "first", "second", etc. are only used for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0022] In addition, if the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0023] In the description of the embodiments of the present application, it should also be noted that unless otherwise clearly specified and limited, if terms such as "set", "installed", "connected", "coupled" are used, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0024] Tooth defects and tooth loss have varying degrees of impact on people's chewing, pronunciation, aesthetics, and even overall health. It is crucial to use artificial materials for restoration to promptly restore the shape and function of the defective or missing teeth. In recent years, with the continuous development of materials science and the increasing aesthetic demands of people, all-ceramic restorations have gained more and more popularity. At present, the dental restoration materials widely used clinically are mainly zirconia ceramics and lithium disilicate glass ceramics. Among them, yttria-stabilized tetragonal zirconia materials are widely used in various types of restorations such as single crowns, fixed partial dentures, and multi-unit bridges due to their high strength (900 - 1400 MPa) and excellent biocompatibility, and have a wider range of indications compared to other dental ceramics. However, since dental zirconia ceramics do not contain a glass phase, it is difficult to effectively treat the tissue surface of the restoration with traditional acid etching techniques to obtain a rough surface and form micromechanical retention. Moreover, zirconia does not contain silicon components and cannot react with silane coupling agents to form Si-O-Si chemistry, resulting in unsatisfactory bonding performance of zirconia restorations.

[0025] Currently, the surface treatment methods for improving the bonding performance of zirconia are mainly divided into physical and chemical methods. Among them, physical methods mainly increase the surface roughness of zirconia to increase the specific surface area of bonding and improve wettability at the same time to achieve good mechanical retention, mainly including sandblasting, silicon coating, selective permeation etching, laser, plasma and other methods. However, sandblasting damages the surface of zirconia and even causes zirconia phase transformation, thus affecting mechanical properties; silicon coating, laser, and plasma require special equipment or are cumbersome to operate and are difficult to apply clinically. Chemical methods use a primer or resin cement containing a phosphate ester functional monomer to form a chemical bond with the surface of zirconia, thereby improving the bonding strength, but still do not meet the requirements of clinical use. In summary, the essential reason for the poor bonding performance between zirconia ceramics and teeth is determined by the composition and structure of zirconia ceramics. Among them, the most important is that zirconia ceramics do not contain silicon elements, making it difficult to form a rough surface through acid etching and unable to undergo a chemical reaction with silane coupling agents. Therefore, introducing silicon elements is the key to improving the bonding performance of dental ZrO 2 restorative materials.

[0026] Traditional glass ceramics have good bonding properties. This is because glass ceramics can be sandblasted or etched with hydrofluoric acid to form a micro-pitted structure, and the resin cement penetrates into the pits to form a micro-interlocking structure with the ceramic matrix. One end of the silane coupling agent undergoes a condensation reaction with the Si-OH groups on the ceramic surface to form Si-O-Si bonds, and the organic group at the other end undergoes a polymerization reaction with the organic groups of the composite resin. Therefore, by combining zirconia with a glass matrix, the bonding properties of zirconia restorations can be effectively improved. However, introducing the glass phase silica to improve the bonding properties will cause a decrease in the mechanical properties of zirconia ceramics. Some studies have shown that the mechanical properties of composite materials are related to the crystal size of the ceramic phase. According to the Hall-Petch law, nanomaterials have better mechanical properties than micron materials.

[0027] Based on the above situation, the present application proposes a dental restorative material and its preparation method. By adopting the new process of "sol-gel - cold sintering - pressureless heat treatment", nano-zirconia is uniformly dispersed in the silica glass matrix. While ensuring the mechanical properties of zirconia, the bonding properties between zirconia ceramics and tooth tissues are improved, which will play a significant promoting role in enhancing the clinical durability of zirconia restorations and is expected to achieve a wider clinical application of such materials in the field of dental restoration. The following will describe the present application in detail with reference to the examples and drawings.

[0028] The preparation method of the dental restorative material proposed in the present application may include: S1, Dissolve tetraethyl orthosilicate in a mixture of a first solvent and a first acidic solution to obtain solution A.

[0029] Tetraethyl orthosilicate is an important precursor for preparing silica. In practical applications, by controlling the types and proportions of the first solvent and the first acidic solution, the pH value and viscosity of solution A can be adjusted, thereby affecting the reaction rate and product properties in subsequent steps. The first solvent can be, for example, methanol or ethanol, and the first acidic solution can be, for example, dilute hydrochloric acid and dilute sulfuric acid.

[0030] S2, Dissolve zirconium propoxide in a second solvent to obtain solution B.

[0031] Zirconium propoxide is an important zirconium source and can be used to prepare nano-zirconia. In practical applications, selecting a suitable second solvent can affect the uniform dispersion effect of zirconium propoxide in solution B. The second solvent may be the same as or different from the first solvent, depending on the solubility of zirconium propoxide and the requirements of subsequent reactions.

[0032] S3, Mix solution A and solution B to obtain solution C.

[0033] S4, Add a second acidic solution to solution C to obtain solution D.

[0034] Adding a second acidic solution may further adjust the pH value of the solution and may initiate or accelerate hydrolysis and polycondensation reactions. These reactions will cause the silicon source and zirconium source to gradually transform into nanoparticles of silicon dioxide and zirconium dioxide, and form a preliminary gel network structure.

[0035] S5, gel the solution D to obtain the corresponding xerogel.

[0036] By controlling conditions such as temperature, humidity, and time, the solution D can be gradually gelled. During the gelation process, the nanoparticles in the solution will connect with each other to form a three-dimensional network structure, and the solvent will be encapsulated in the network structure to form a gel.

[0037] S6, after grinding the xerogel and removing the residual organic matter, obtain the nano zirconia / silica composite powder.

[0038] S7, prepare the nano zirconia / silica composite powder into nano zirconia reinforced silica glass ceramics.

[0039] The following further illustrates the present application through specific examples: Example 1 (1) Use zirconium propoxide and tetraethyl orthosilicate as precursors. Dissolve zirconium propoxide in isopropanol and stir for 2 h to obtain solution B. Dissolve tetraethyl orthosilicate in ethanol and dilute hydrochloric acid and stir for 2 h to obtain solution A. The volume fractions of zirconium propoxide and tetraethyl orthosilicate are 80% and 20% respectively, the volume of isopropanol is 1.25 times that of zirconium propoxide, and the volumes of ethanol and dilute hydrochloric acid are 26.5% and 8% of the volume of tetraethyl orthosilicate respectively.

[0040] (2) Slowly introduce the well-stirred zirconium propoxide solution into the tetraethyl orthosilicate solution and continue to stir for 2 h to obtain solution C.

[0041] (3) After solution C is uniform, gradually add concentrated hydrochloric acid with a volume fraction of 25% of zirconium propoxide until the white precipitate is completely dissolved to obtain solution D.

[0042] (4) Place it in an oven at 60 °C and keep it warm for 3 days for gelation, then raise the temperature to 120 °C and keep it warm for 3 days to form a xerogel.

[0043] (5) Finally, use planetary ball milling for 1 h to obtain the zirconia / silica composite powder.

[0044] (6) Mix the prepared composite powder, in which the molar ratio of zirconia to silica is 65:35, with deionized water evenly, load it into a steel mold, apply a pressure of 350 MPa, and keep the pressure for 10 min, then increase the temperature at a heating rate of 10 °C·min −1 to 180 °C, and keep it warm for 1 h to obtain a composite green body.

[0045] (7) Heat-treat the composite green body. First, heat it from room temperature to 200 °C at a heating rate of 10 °C·min −1 , and hold for 12 h to remove the residual moisture in the green body; then heat it to 900 °C at a heating rate of 5 °C·min −1 , and hold for 2 h; continue to heat it to 1300 °C at a heating rate of 2 °C·min −1 , and hold for 2 h to obtain a nano-zirconia-reinforced silica glass-ceramic with uniform properties.

[0046] Test the properties of the nano-zirconia-reinforced silica glass-ceramic obtained in Example 1. Use a field emission scanning electron microscope (FESEM) to characterize the zirconia / silica composite powder prepared in Example 1. As Figure 1 shown, it is a schematic diagram of the microstructure of the zirconia / silica composite powder obtained in Example 1. It can be seen from Figure 1 that the composite powder is in the form of nanoparticles with a uniform size distribution of about 35 nm, which improves the sintering activity. After cold sintering, the powder is preliminarily sintered to form a porous composite green body, and further pressureless heat treatment densifies the green body. The density of the green body measured by the Archimedes drainage method is 3.22 g·cm −3 , and the relative density is 72.1%. After heat treatment, the density of the nano-zirconia-reinforced silica glass-ceramic reaches 4.14 g·cm −3 , and the relative density reaches 92.7%. After cold sintering, the sample is preliminarily sintered and the particles hardly grow. As Figure 2 shown, it is a schematic diagram of the micro-morphology of the nano-silica / zirconia green body sintered by the cold sintering method in Example 1. It can be seen from Figure 2 that there are still a large number of pores in the green body. Through subsequent heat treatment, silica melts and forms glass, and nano-zirconia is uniformly distributed in the silica glass matrix to form a uniform nano-zirconia-reinforced silica glass-ceramic composite material. As Figure 3 shown, it is a schematic diagram of the micro-morphology of the nano-zirconia-reinforced silica glass-ceramic prepared in Example 1 of this application. In addition, the mechanical properties of the nano-zirconia-reinforced silica glass-ceramic prepared in Example 1 were also tested. The test results of the mechanical properties show that the elastic modulus and hardness of the nano-zirconia-reinforced silica glass-ceramic obtained in Example 1 are 125.1 GPa and 9.3 GPa respectively, and the biaxial bending strength reaches 534.9 MPa. At the same time, the bonding strength between the prepared nano-zirconia-reinforced silica glass-ceramic and resin cement can reach 32.6 MPa.

[0047] Example 2 Example 2 is only different from Example 1 in that in Example 2, the volume fractions of zirconium propoxide and tetraethyl orthosilicate are 69% and 31% respectively, and the molar ratio of zirconia to silica in the prepared composite powder is 50:50.

[0048] The same performance tests as in Example 1 were carried out on the nanozirconia-reinforced silica glass-ceramics obtained in Example 2, and the results are as follows: the green density is 2.90 g·cm −3 , and the relative density is 74.2%; after heat treatment, the density of the nanozirconia-reinforced silica glass-ceramics reaches 3.76 g·cm −3 , and the relative density reaches 95.9%. The microscopic morphology of the formed porous nano green body is similar to Figure 2 , and the microscopic morphology of the nanozirconia-reinforced silica glass-ceramics after heat treatment is similar to Figure 3 . The mechanical property tests show that the elastic modulus and hardness are 76.4 GPa and 6.6 GPa respectively, and the biaxial bending strength reaches 469.7 MPa. At the same time, the bonding strength between the nanozirconia-reinforced silica glass-ceramics obtained in Example 2 and resin cement reaches 34.8 MPa.

[0049] Example 3 Example 3 is only different from Example 1 in that in Example 3, the volume fractions of zirconium propoxide and tetraethyl orthosilicate are 90% and 10% respectively, and the molar ratio of zirconia to silica in the prepared composite powder is 80:20.

[0050] The same performance tests as in Example 1 were carried out on the sintered specimens of this example, and the results are as follows: the green density is 3.49 g·cm −3 , and the relative density is 69.2%; after heat treatment, the density of the glass-ceramics reaches 4.58 g·cm −3 , and the relative density reaches 90.7%. The microscopic morphology of the formed porous nano green body is similar to Figure 2 , and the microscopic morphology of the nanozirconia-reinforced silica glass-ceramics obtained after heat treatment is similar to Figure 3 . The mechanical property tests show that the elastic modulus and hardness are 129.7 GPa and 10.8 GPa respectively, and the biaxial bending strength reaches 563.2 MPa. At the same time, the bonding strength between the glass-ceramics and resin cement reaches 29.5 MPa.

[0051] Example 4 Example 4 is only different from Example 1 in that in Example 4, the volume fractions of zirconium propoxide and tetraethyl orthosilicate are 95% and 5% respectively, and the molar ratio of zirconia to silica in the prepared composite powder is 90:10.

[0052] The sintered specimens of this embodiment were subjected to the same performance tests as in Example 1, and the results are as follows: the density of the green body was 3.51 g·cm −3 , and the relative density was 64.0%; the density of the nano-zirconia-reinforced silica glass-ceramics obtained after heat treatment reached 5.12 g·cm −3 , and the relative density reached 93.8%. The microscopic morphology of the formed porous nano green body was similar to that of Figure 2 , and the microscopic morphology of the glass-ceramics obtained after heat treatment was similar to that of Figure 3 . The mechanical property tests showed that the elastic modulus and hardness were 166.5 GPa and 11.6 GPa respectively, and the biaxial bending strength reached 584.3 MPa. At the same time, the bonding strength between the glass-ceramics and resin cement reached 27.6 MPa.

[0053] The cold sintering process and the heat treatment after the cold sintering process of the present application will be described below through Examples 5 to 9: Example 5 The main difference between Example 5 and Example 1 is that in Example 5: In the cold sintering process: the prepared zirconia / silica composite powder with a molar ratio of 65:35 was mixed evenly with deionized water, then loaded into a steel mold, a pressure of 300 MPa was applied, and the pressure was maintained for 20 min, and then the temperature was raised to 120 °C at a heating rate of 10 °C·min −1 , and after holding for 1.5 h, a composite green body was obtained.

[0054] In the heat treatment process: heat treatment was carried out at 1100 °C and held for 2 h to obtain nano-zirconia-reinforced silica glass-ceramics.

[0055] Example 6 The main difference between Example 6 and Example 1 is that in Example 6: In the cold sintering process: the prepared zirconia / silica composite powder with a molar ratio of 65:35 was mixed evenly with deionized water, then loaded into a steel mold, a pressure of 400 MPa was applied, and the pressure was maintained for 30 min, and then the temperature was raised to 220 °C at a heating rate of 10 °C·min −1 , and after holding for 0.5 h, a composite green body was obtained.

[0056] In the heat treatment process: heat treatment was carried out at 1400 °C and held for 2 h to obtain nano-zirconia-reinforced silica glass-ceramics.

[0057] Example 7 The main difference between Example 7 and Example 2 is that in Example 7: In the cold sintering process: The prepared zirconia / silica composite powder with a molar ratio of 50:50 is mixed evenly with deionized water, then loaded into a steel mold, a pressure of 380 MPa is applied, and the pressure is maintained for 25 min. Then, it is heated to 140 °C at a heating rate of 10 °C·min −1 and kept at this temperature for 3 h to obtain a composite green body.

[0058] In the heat treatment process: Heat treatment is carried out at 1100 °C and kept for 2 h to obtain nano-zirconia reinforced silica glass ceramics.

[0059] Example 8 The main difference between Example 8 and Example 3 is that in Example 8: In the cold sintering process: The prepared zirconia / silica composite powder with a molar ratio of 80:20 is mixed evenly with deionized water, then loaded into a steel mold, a pressure of 360 MPa is applied, and the pressure is maintained for 15 min. Then, it is heated to 160 °C at a heating rate of 10 °C·min −1 and kept at this temperature for 2 h to obtain a composite green body.

[0060] In the heat treatment process: Heat treatment is carried out at 1200 °C and kept for 2 h to obtain nano-zirconia reinforced silica glass ceramics.

[0061] Example 9 The main difference between Example 9 and Example 3 is that in Example 9: In the cold sintering process: The prepared zirconia / silica composite powder with a molar ratio of 80:20 is mixed evenly with deionized water, then loaded into a steel mold, a pressure of 320 MPa is applied, and the pressure is maintained for 10 min. Then, it is heated to 180 °C at a heating rate of 10 °C·min −1 and kept at this temperature for 2.5 h to obtain a composite green body.

[0062] In the heat treatment process: Heat treatment is carried out at 1400 °C and kept for 2 h to obtain nano-zirconia reinforced silica glass ceramics.

[0063] The cold sintering process can be specifically carried out in the following way: The nano-silica / zirconia composite powder prepared by the sol-gel method and deionized water are ground in a mortar. After being mixed evenly, they are loaded into a steel mold. The steel mold is placed at the center position between the upper and lower steel pads. The pressure loading system is started to apply an axial pressure of 300 - 400 MPa to the two ends of the steel pads. After maintaining the pressure for 10 - 30 min, it is heated to the target temperature and kept at this temperature with pressure maintained for 0.5 - 3 h. During this process, ZrO 2The particles dissolve at the solid-liquid interface. When the temperature is higher than 100 °C, the water in the liquid volatilizes, causing supersaturation to form at the solid-liquid interface layer, so that the dissolved cations precipitate at the interface layer, that is, "dissolution-precipitation" occurs. At the same time, at a lower temperature, the zirconia grains still maintain a nanoscale size. In addition, the applied pressure and the added liquid can promote the preliminary sintering of the powder particles. Finally, the glass-ceramics are further densified by pressureless heat treatment. It should be noted that among the cold sintering process parameters proposed in this application, if the cold sintering temperature is too low, it is difficult to sinter together to form a complete green body. If the cold sintering pressure is too high, it is also easy to cause the sample to delaminate. Therefore, the cold sintering process parameters in this application are designed by combining and using scenarios. In addition, when heat-treating at a temperature of 1100-1400 °C after cold sintering, if the heat treatment temperature is too high, it will also cause the silicon oxide to melt and the sample to collapse.

[0064] In the above embodiment, the first solvent is anhydrous ethanol, the second solvent is isopropyl alcohol, the first acidic solution is dilute hydrochloric acid, and the second acidic solution is concentrated hydrochloric acid. In other embodiments of the present application, the solvent and the acidic solution can be adjusted adaptively. The volume of the first solvent is 25-30% of tetraethyl orthosilicate, the volume of the second solvent is 1.2-1.5 times that of zirconium propoxide, the added volume of the first acidic solution is 8-10% of tetraethyl orthosilicate, and the added volume of the second acidic solution is 7-10% of solution C. It should be noted that if the added volume of the second acidic solution is more than 10% of solution C, a large amount of white and insoluble precipitate will form. In actual operation, when adding the second acidic solution, it can be slowly dripped.

[0065] This application first uses the sol-gel method to generate nano-zirconia / silica composite powder, then uses the cold sintering method to preliminarily sinter the composite powder to form a composite green body, and finally prepares a uniform nano-zirconia reinforced silica glass-ceramic composite material through heat treatment. While greatly improving the bonding performance of zirconia, its good mechanical properties are ensured. Among them, the cold sintering method is a new type of sintering method. An appropriate amount of solvent is added to the ceramic powder raw material to make the particle surface uniformly wet, so as to promote the close contact between the liquid phase and the solid phase. Under the conditions of low temperature and high pressure, during the dissolution-precipitation process of ceramic particles, an amorphous phase is precipitated to inhibit the further growth of grains, and the presintering of nano-ceramics can be realized, and it is also beneficial to clinically process into the shape of teeth. The temperature of the subsequent heat treatment is lower than the sintering temperature of pure zirconia ceramics, greatly reducing the energy consumption. It can also be verified that the uniform nano-zirconia reinforced silica glass-ceramics obtained in this application can improve the bonding performance of zirconia, and will play a significant role in promoting the clinical durability of zirconia restorations, etc., and is expected to realize the wider clinical application of this type of material in the field of dental restoration. The obtained nano-zirconia reinforced silica glass-ceramics integrate high strength, hardness and elastic modulus similar to those of tooth enamel, and good bonding performance.

[0066] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A method for preparing a dental restorative material, characterized in that: include: dissolving tetraethyl orthosilicate in a mixture of a first solvent and a first acidic solution to obtain a solution A; dissolving zirconium n-propoxide in a second solvent to obtain a solution B; Mixing solution A and solution B to obtain solution C; Adding a second acidic solution to the solution C to obtain a solution D; gelling the solution D to obtain a corresponding xerogel; After grinding the dry gel and removing residual organic matter, a nano zirconium oxide / silicon dioxide composite powder is obtained; Nano-zirconia / silicon dioxide composite powder is prepared into nano-zirconia reinforced silicon dioxide glass ceramics.

2. The method for preparing a dental restorative material according to claim 1, characterized in that: In terms of volume percentage, when preparing solution A and solution B: tetraethyl orthosilicate is 5-50 vol.%, zirconium n-propoxide is 50-95 vol.%; The volume of the first solvent is 25-30% of tetraethyl orthosilicate, and the volume of the second solvent is 1.2-1.5 times of zirconium n-propoxide.

3. The method for preparing a dental restoration material according to claim 1, characterized in that: The added volume of the first acidic solution is 8-10% of tetraethyl orthosilicate, and the added volume of the second acidic solution is 7-10% of solution C.

4. The method for preparing a dental restorative material according to claim 1, characterized in that: The purity of the tetraethyl orthosilicate is greater than 99.99%, and the concentration of the zirconium n-propoxide is 70 wt.%.

5. The method for preparing a dental restorative material according to claim 1, characterized in that: The first solvent is anhydrous ethanol, the second solvent is isopropanol, the first acidic solution is dilute hydrochloric acid, and the second acidic solution is concentrated hydrochloric acid.

6. The method for preparing a dental restorative material according to claim 5, characterized in that: The concentration of the dilute hydrochloric acid is 0.4 mol·L -1 , the concentration of the concentrated hydrochloric acid is 37wt.%.

7. The method for preparing a dental restoration material according to claim 5, characterized in that: The method of preparing nano-zirconia / silicon dioxide composite powder into nano-zirconia reinforced silicon dioxide glass ceramics comprises: Mixing nano zirconium oxide / silicon dioxide composite powder and deionized water; After mixing, cold firing is performed; during cold firing, a load of 300-400 MPa is applied, the pressure is maintained for 10-30 minutes, the temperature is raised to 140-220° C. and the temperature is maintained for 0.5-3 hours to obtain a green body; The green body is heat treated at 1100-1400°C for 0.5-3h to obtain nano-zirconia reinforced silica glass ceramics.

8. The method for preparing a dental restorative material according to claim 7, characterized in that: The green body is heat treated at a temperature of 1100-1400° C. for 0.5-3 hours, including heat treatment in five stages: The first stage: 10℃·min -1 The heating rate is raised to 200°C; The second stage: keep warm at 200℃ for 12h; The third stage: from 200℃ to 5℃·min -1 The heating rate is increased to 900℃; Stage 4: Keep at 900℃ for 2h; The fifth stage: from 900℃ to 2℃·min -1 The heating rate is increased to 1100~1400℃.

9. The method for preparing a dental restorative material according to claim 7, characterized in that: When the nano zirconium oxide / silicon dioxide composite powder and deionized water are mixed, the mass ratio of the nano zirconium oxide / silicon dioxide composite powder to the deionized water is (60-80): (20-40); The heating rate of the cold firing is 10°C min -1 .

10. A dental restorative material obtained by the preparation method of a dental restorative material according to any one of claims 1 to 9.

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