A method for manufacturing a microstructured dental crown from scrap zirconium blocks

Abstract

The application discloses a method for manufacturing a microstructure dental crown from waste zirconium blocks, comprising the following steps: preparing waste zirconium powder from waste zirconium blocks, wherein the waste zirconium powder comprises zirconium oxide; removing iron from the waste zirconium powder in a strong magnetic environment to obtain waste zirconium powder raw material; performing pre-burning treatment on the waste zirconium powder raw material; preparing a photocuring slurry from the pre-burned waste zirconium powder raw material, wherein the photocuring slurry comprises ultraviolet inhibitors; performing photocuring printing on the photocuring slurry to obtain a zirconium oxide dental crown blank; performing segmented sintering on the zirconium oxide dental crown blank to obtain a microstructure dental crown; and arranging a plurality of grooves on the inner bottom surface of the microstructure dental crown; the method can be used to manufacture a dental crown with complex microstructure from waste zirconium blocks through 3D printing, so that the dental crown is not easy to fall off during use, the forming precision is high during the manufacturing process, and the phenomenon of explosive aggregation is avoided, so that a broken bubble-shaped structure is not generated on the surface or inside of the artificial tooth.

Description

Technical Field

[0001] This invention relates to the field of dental prostheses, and more particularly to a method for manufacturing microstructured dental crowns using waste zirconium blocks. Background Technology

[0002] Zirconia ceramics have excellent mechanical properties, high hardness and wear resistance, high biocompatibility and good appearance, making them the main material for preparing dentures or modifying teeth. However, since common denture processing methods use zirconia raw materials, a lot of waste zirconia blocks are generated, resulting in waste of zirconia blocks.

[0003] There are three main methods for traditionally recycling waste zirconium:

[0004] 1. Acid leaching method: Acid leaching is one of the more widely used methods for recycling waste zirconium oxide. Its main principle is to convert the metal components in waste zirconium oxide into soluble ions by adding a certain amount of acidic reagent, and then recover and separate them through the principle of reaction equilibrium. However, the zirconium oxide powder obtained by this method is too reactive. When used to fabricate dentures using this powder in 3D printing, explosive polymerization occurs, leading to ruptured bubble-like structures on or inside the denture, resulting in low denture strength. Furthermore, the zirconium oxide powder obtained by this method contains acid residue, which has adverse effects on human health and the environment.

[0005] 2. Alkali leaching method: The alkali leaching method mainly involves adding an alkaline solution and using the dissolution-precipitation principle to recover and separate impurity metal components from waste zirconium oxide. However, the zirconium oxide powder obtained by this method is too reactive. When it is used to fabricate dentures using 3D printing, bursting occurs, resulting in ruptured bubble-like structures on or inside the denture, leading to low denture strength. Furthermore, the zirconium oxide powder obtained by this method contains alkaline residue, which has adverse effects on human health and the environment, and the waste liquid treatment also poses environmental problems.

[0006] However, the current dentures, especially crowns, can be fabricated using 3D printing to create various complex structures, improving denture performance without wasting materials. However, this requires high-quality raw materials. If the raw materials contain impurities or zirconia powder with excessive activity, the denture strength will be significantly reduced, rendering it unusable.

[0007] Therefore, how to prepare high-strength microstructured dental crowns by recycling waste zirconium blocks has become an urgent problem to be solved in this field. Summary of the Invention

[0008] To address the aforementioned technical issues, a method for manufacturing microstructured dental crowns using waste zirconium blocks is provided. This method enables the fabrication of dental crowns with complex microstructures using waste zirconium blocks via 3D printing. This results in high bonding strength between the crown and the adhesive, preventing the crown from easily falling off during use. Furthermore, it achieves high molding precision during fabrication while avoiding the problem of low denture strength caused by bursting polymerization, which leads to ruptured bubble-like structures on or inside the denture surface.

[0009] The present invention provides a method for manufacturing dental crowns with microstructures using waste zirconium blocks.

[0010] Waste zirconium powder is obtained by removing iron from waste zirconium powder in a strong magnetic environment;

[0011] Pre-calcining of waste zirconium powder raw materials;

[0012] A photocurable slurry is prepared using the pre-calcined waste zirconium powder raw material, and the photocurable slurry includes a UV inhibitor;

[0013] The zirconia crown preform is obtained by photocuring and printing using the aforementioned photocurable slurry.

[0014] The zirconia crown blank is sintered in segments to obtain a microstructured crown;

[0015] The inner bottom surface of the microstructure crown is provided with several grooves; the distance between the bottom surface of the groove and the occlusal surface of the opposite outer surface of the microstructure crown is not less than 0.8 mm;

[0016] Microstructured crown density ≥6.03 g / cm³ 3 It has a density of over 98%, a strength of ≥800MPa, and a coefficient of thermal expansion of ≤11*10. -6 / K, fracture toughness ≥8MPa·m 1 / 2 .

[0017] The advantage of the previous step is that by removing iron from the waste zirconium powder in a strong magnetic environment, it is beneficial to avoid the iron element in the waste zirconium powder raw material from causing explosive polymerization of the subsequently prepared light-cured slurry during light curing, which would lead to ruptured bubble-like structures on or inside the denture surface, and at the same time, avoid changes in the color of the denture.

[0018] By pre-calcining the waste zirconium powder raw material, the organic impurities in the waste zirconium powder are decomposed and volatilized. The zirconium element is converted into zirconium oxide after pre-calcination, which realizes the purification of waste zirconium powder raw material and avoids the introduction of other impurities. At the same time, the metallic impurities such as Mg and Ca contained in the waste zirconium powder react into oxides during the preheating process, which become sintering aids in the subsequent sintering process of zirconium oxide crown blanks, which helps to reduce the sintering temperature.

[0019] The zirconia crown preform is obtained by photocuring and printing with the aforementioned photocurable slurry, thus realizing the preparation of zirconia crown preforms with complex microstructures with high precision.

[0020] The inclusion of UV inhibitors in the light-curing slurry helps to avoid the problem of bursting during light curing molding, which can lead to ruptured bubble-like structures on or inside the denture surface. This facilitates the use of waste zircon blocks to 3D print high-strength crowns with complex microstructures.

[0021] The microstructure crown has several grooves on its inner bottom surface, which allows the microstructure crown to form a tenon-and-mortise structure with the cured adhesive, improving the bonding strength with the adhesive and making the crown less likely to fall off during use. At the same time, the distance between the bottom surface of the groove and the opposite outer occlusal surface of the microstructure crown is not less than 0.8mm, avoiding problems such as breakage caused by the outer occlusal surface of the crown being too thin.

[0022] Furthermore, the waste zirconium powder preparation process includes:

[0023] The waste zirconium blocks are crushed and then screened to obtain waste zirconium powder by removing the material below a 100-mesh screen. Preferably, the crushing equipment is a drum mill, which includes grinding balls with diameters of 10mm, 25mm, and 50mm in a ratio of (2-4):(2-4):(5-6), a grinding speed of 200-250 r / min, a stop of 3-5 min every 25-32 min, and a grinding time of 12-36 h.

[0024] The beneficial effect of the previous step is that after the waste zirconium blocks are crushed, the material below the 100-mesh sieve is screened. The particle size of the waste zirconium powder is conducive to the subsequent iron removal in a strong magnetic environment. At the same time, it avoids the problem of rapid grain growth during the subsequent pre-sintering process caused by the waste zirconium powder particles being too small and having high activity. This avoids the problem of low microstructure crown strength caused by excessively large grains during the subsequent sintering process of the zirconia crown blank.

[0025] By grinding at a speed of 200-250 r / min and stopping for 3-5 minutes every 25-32 minutes, the problem of rapid grain growth caused by excessively long grinding time is avoided.

[0026] Furthermore, the pre-calcination process for the waste zirconium powder raw material involves holding the waste zirconium powder raw material at 600-700℃ for 2-4 hours.

[0027] The advantages of the previous step are that it decomposes and volatilizes the organic impurities in the waste zirconium powder, and the zirconium element is converted into zirconium oxide after preheating treatment, thereby purifying the waste zirconium powder raw material while avoiding the introduction of other impurities. In addition, the metallic impurities such as Mg and Ca contained in the waste zirconium powder are converted into metal oxides during the pre-calcination process. The metal oxides become sintering aids in the subsequent sintering process of zirconium oxide crown blanks, which helps to reduce the sintering temperature.

[0028] Furthermore, the preparation process of the photocurable slurry includes the following steps:

[0029] Pre-calcined waste zirconium powder raw material, solvent, and additives are mixed and ground in proportion to obtain a powder slurry; a resin slurry is prepared, the resin slurry including UV inhibitor, polymer monomer, and initiator; the powder slurry, resin slurry, and dispersant are mixed evenly to obtain the photocurable slurry.

[0030] The beneficial effect of the previous step is that the above method enables the preparation of a photocurable slurry containing waste zirconium powder raw material; at the same time, it enables the preparation of a resin slurry, which includes a UV inhibitor, a polymerization monomer, and an initiator.

[0031] This helps avoid the problem of bursting during light curing, which can cause ruptured bubble-like structures on or inside the denture surface. This makes it easier to use waste zirconium blocks to 3D print high-strength crowns with complex microstructures.

[0032] Furthermore, the mass ratio of the waste zirconium powder raw material, solvent, and additive is (45-55):(45-55):1; the mass ratio of the waste zirconium powder raw material to the grinding ball during grinding is (45-55):100, the grinding time is 24-48h, and the particle D50 in the obtained powder slurry is less than 500nm.

[0033] The solvent is methanol or ethanol; the additive is castor oil or polyacrylic acid.

[0034] Furthermore, the resin slurry comprises UV inhibitor, polymeric monomer, and initiator in a mass ratio of (0.1-0.8):100:(1-3);

[0035] The UV inhibitor, polymeric monomer, and initiator are mixed and then dispersed by ultrasonication to obtain a resin slurry.

[0036] The beneficial effect of the previous step is that by using a grinding ratio of waste zirconium powder to grinding balls of (45-55):100 and a grinding time of 24-48 hours, the particle size (D50) in the resulting powder slurry is less than 500 nm. This reduces the size of the pre-calcined waste zirconium powder grains, thereby improving the activity of the waste zirconium powder in the powder slurry to a certain extent. The fact that the particle size (D50) in the powder slurry is less than 500 nm ensures that the pre-calcined waste zirconium powder grains have a certain level of activity, while avoiding the problem of reduced microstructure crown strength caused by excessively large waste zirconium powder grains.

[0037] By mixing UV inhibitors, monomers, and initiators and then dispersing them by ultrasound, a resin slurry is obtained, achieving uniform dispersion within the resin slurry. This avoids the problem of increased activity of monomers and initiators due to temperature rise during dispersion, thus preventing problems such as initial polymerization of monomers.

[0038] This helps to avoid the problem of burst polymerization during light curing, which can lead to ruptured bubble-like structures on or inside the denture surface.

[0039] Furthermore, the UV inhibitor includes one or more of ferrous aminosulfonate, ferrous titanate, and ferrous fluoride;

[0040] The initiator includes one or more of triphenylthiofluoroborate, diaryliodomonium salt, and triarylthiomonium salt;

[0041] The polymeric monomers include a first polymeric monomer and a second polymeric monomer in a mass ratio of (30-40):(60-70);

[0042] The first polymerization monomer includes one or two of 1,4-cyclohexyldiethanol divinyl ether and tripropylene glycol diacrylate;

[0043] The second polymerizable monomer includes one or more of trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, and pentaerythritol triacrylate.

[0044] The advantage of using the previous step is that the use of one or more initiators, including triphenylthiofluoroborate, diaryliodonium salt, and triarylthiodonium salt, facilitates stable polymerization during the photocuring polymerization process.

[0045] By using UV inhibitors comprising one or more of ferrous aminosulfonate, ferrous titanate, and ferrous fluoride, the UV inhibitors absorb excess UV light under UV and visible light irradiation, achieving fine adjustment of the microstructure. This helps avoid the problem of burst polymerization during light curing, which can lead to ruptured bubble-like structures on or inside the denture surface. Simultaneously, the UV inhibitors contain fluoride ions, which can be slowly released into the denture, thus helping to prevent tooth decay. Furthermore, the presence of aminosulfonate ions in the UV inhibitors helps to wet the powder and improve its dispersibility.

[0046] The polymerizing monomers comprise a first polymerizing monomer and a second polymerizing monomer in a mass ratio of (30-40):(60-70). The first polymerizing monomer is a bifunctional polymerizing monomer, and the second polymerizing monomer is a trifunctional polymerizing monomer. This allows for a faster polymerization rate using the second polymerizing monomer, which is beneficial for obtaining a high-precision microstructure. Simultaneously, the high degree of cross-linking during polymerization avoids the problem of burst polymerization that can occur during rapid polymerization, leading to ruptured bubble-like structures on or inside the denture surface. The second polymerizing monomer also helps to reduce the viscosity of the resin slurry and improve its fluidity. The mass ratio of the first and second polymerizing monomers (30-40):(60-70) achieves good resin slurry fluidity, a high polymerization rate during polymerization, high molding precision, and avoids burst polymerization that could cause ruptured bubble-like structures on or inside the denture surface.

[0047] Furthermore, the mass ratio of the powder slurry, resin slurry, and dispersant is (2-5):200:(80-100);

[0048] The dispersant is an alkanoic ammonium salt of a block copolymer having acidic groups.

[0049] Furthermore, the segmented sintering process of the zirconia crown blank includes the following steps:

[0050] The zirconia crown blank is heated from room temperature to 50-70℃ at a rate of 1-4℃ / min and held at 50-70℃ for 5-30 min; from 50-70℃ to 100-120℃ at a rate of 9-10℃ / min; from 100-120℃ to 300-360℃ at a rate of 3-4℃ / min; from 300-360℃ to 580-620℃ at a rate of 2-3℃ / min; and from 580-620℃ to 1450-1520℃ at a rate of 0.5-1.5℃ / min.

[0051] The beneficial effect of the previous step is that by heating the zirconia crown blank from room temperature to 50-70℃ at a heating rate of 1-4℃ / min, the cross-linking of the zirconia crown blank is fully achieved, the strength of the zirconia crown blank is improved, and the problem of deformation or damage during the subsequent volatilization of volatiles is avoided.

[0052] By heating from 50-70℃ to 100-120℃ at a rate of 9-10℃ / min, small-molecule volatiles in the zirconia crown blank are rapidly volatilized to form small-diameter through-pores; by heating from 100-120℃ to 300-360℃ at a rate of 3-4℃ / min, large-molecule volatiles in the zirconia crown blank are slowly decomposed, and larger molecular weight volatiles volatilize on the basis of small-diameter through-pores to form medium-diameter through-pores, thus avoiding damage or cracks to the zirconia crown blank during the process.

[0053] By heating from 300-360℃ to 580-620℃ at a rate of 2-3℃ / min, the decomposed macromolecular volatiles are volatilized through the medium-diameter through-hole, thus removing most of the volatiles while avoiding damage or cracks to the zirconia crown blank.

[0054] By heating from 580-620℃ to 1450-1520℃ at a rate of 0.5-1.5℃ / min, zirconia powder is ceramicized, and the crystals grow slowly without the formation of bubbles, which helps to improve the strength of the microstructured crown.

[0055] Furthermore, the groove includes a connecting groove and a limiting groove; the connecting groove contacts the inner side of the microstructure crown, and the end of the connecting groove away from the inner side of the microstructure crown is connected to the limiting groove; the minimum cross-sectional length of the connecting groove is greater than the cross-sectional length of the limiting groove.

[0056] The cross-section of the groove of the joint is one of pentagon, hexagon, or octagon.

[0057] The advantage of the previous step is that when the microstructure crown is connected to the adhesive, the large contact area between the cured adhesive and the inner side of the crown increases the bonding strength. At the same time, the minimum length of the cross-section of the connecting groove is greater than the length of the cross-section of the limiting groove, so that the cured adhesive is held in the groove. The microstructure crown and the cured adhesive form a tenon and mortise structure, which further increases the connection strength between the microstructure crown and the cured adhesive and avoids the problem of crown falling off during use. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the microstructured dental crown of Example 1;

[0059] Figure 2This is a schematic diagram of the groove structure of the microstructured crown in Example 1. Detailed Implementation

[0060] To better understand the technical solution of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0061] Example 1:

[0062] This embodiment provides a method for manufacturing a microstructured dental crown using waste zirconium blocks, wherein the waste zirconium blocks are prepared into waste zirconium powder, and the waste zirconium powder includes zirconium oxide.

[0063] The waste zirconium powder preparation process includes:

[0064] The waste zirconium blocks are crushed and then screened to obtain waste zirconium powder by removing the material below a 100-mesh sieve. The crushing equipment is a grinding equipment, specifically a planetary mill. The grinding equipment includes grinding balls with diameters of 10mm, 25mm, and 50mm in a ratio of 3:3:5. The grinding speed is 225r / min, with a 4-min stop every 28min, and the grinding time is 24h.

[0065] Waste zirconium powder is obtained by removing iron from waste zirconium powder in a strong magnetic environment;

[0066] The waste zirconium powder raw material is pre-calcined; the pre-calcination process involves keeping the waste zirconium powder raw material at 650°C for 3 hours.

[0067] A photocurable slurry is prepared using the pre-calcined waste zirconium powder raw material, the photocurable slurry comprising a UV inhibitor; the preparation process of the photocurable slurry includes the following steps:

[0068] Pre-calcined waste zirconium powder raw material, solvent, and additives are mixed and ground in proportion to obtain a powder slurry; a resin slurry is prepared, the resin slurry including UV inhibitor, polymer monomer, and initiator; the powder slurry, resin slurry, and dispersant are mixed evenly to obtain the photocurable slurry;

[0069] The mass ratio of the waste zirconium powder raw material, solvent, and additives is 50:50:1; the mass ratio of the waste zirconium powder raw material to the grinding balls is 50:100, the grinding time is 36h, and the particle D50 of the obtained powder slurry is 480nm.

[0070] The solvent is ethanol; the additive is castor oil.

[0071] The resin slurry comprises UV inhibitor, polymeric monomer, and initiator in a mass ratio of 0.45:100:2;

[0072] The UV inhibitor, polymerizing monomer, and initiator are mixed and then dispersed by ultrasonication to obtain a resin slurry;

[0073] The UV inhibitor includes ferrous aminosulfonate; the initiator includes triphenylthiofluoroborate.

[0074] The polymeric monomers include a first polymeric monomer and a second polymeric monomer in a mass ratio of 35:65;

[0075] The first monomer comprises 1,4-cyclohexyldiethanol dialvinyl ether; the second monomer comprises trimethylolpropane triacrylate.

[0076] The mass ratio of the powder slurry, resin slurry, and dispersant is 3.5:200:90;

[0077] The dispersant is an alkanoic ammonium salt of a block copolymer having acidic groups.

[0078] The zirconia crown preform is obtained by photocuring and printing using the aforementioned photocurable slurry.

[0079] The zirconia crown blank is sintered in segments to obtain a microstructured crown; the segmented sintering process of the zirconia crown blank includes the following steps:

[0080] The zirconia crown blank was heated from room temperature to 60°C at a rate of 2.5°C / min and held at 60°C for 18 min; from 60°C to 110°C at a rate of 9.5°C / min; from 110°C to 330°C at a rate of 3.5°C / min; from 330°C to 600°C at a rate of 2.5°C / min; and from 600°C to 1485°C at a rate of 1°C / min.

[0081] The inner bottom surface of the microstructure crown is provided with several grooves; the distance between the bottom surface of the groove and the occlusal surface of the opposite outer surface of the microstructure crown is not less than 0.8 mm; the groove includes a connecting groove and a limiting groove; the connecting groove contacts the inner side of the microstructure crown, and the end of the connecting groove away from the inner side of the microstructure crown is connected to the limiting groove; the minimum length of the cross-section of the connecting groove is greater than the length of the cross-section of the limiting groove; the cross-section of the connecting groove is octagonal.

[0082] Microstructure crown density: 6.04 g / cm³ 3 It has a density of over 99%, a strength of 835 MPa, and a coefficient of thermal expansion of 9.5*10. -6 / K, fracture toughness is 8.8MPa·m1 / 2 .

[0083] Example 2:

[0084] The contents that are the same as in Example 1 will not be repeated here; the different aspects of this embodiment compared to Example 1 are as follows:

[0085] This embodiment provides a method for manufacturing a microstructured dental crown using waste zirconium blocks, wherein the waste zirconium powder preparation process includes:

[0086] The ball milling equipment contains grinding balls with diameters of 10mm, 25mm, and 50mm in a ratio of 4:4:6. The ball milling speed is 210r / min, and it stops for 5min every 31min. The ball milling time is 16h.

[0087] The waste zirconium powder raw material was kept at 680°C for 2.5 hours.

[0088] The mass ratio of the waste zirconium powder raw material, solvent, and additives is 46:53:1; the mass ratio of the waste zirconium powder raw material to the grinding balls during grinding is 46:100, the grinding time is 26h, and the particle D50 of the obtained powder slurry is 490nm.

[0089] The solvent is methanol; the additive is polyacrylic acid.

[0090] The resin slurry comprises UV inhibitor, polymeric monomer, and initiator in a mass ratio of 0.7:100:3;

[0091] The UV inhibitor comprises ferrous titanate; the initiator comprises diaryliodonium salt;

[0092] The polymeric monomers include a first polymeric monomer and a second polymeric monomer in a mass ratio of 38:68;

[0093] The first monomer comprises tripropylene glycol diacrylate; the second monomer comprises trimethylolpropane trimethacrylate.

[0094] The mass ratio of the powder slurry, resin slurry, and dispersant is 4:200:95;

[0095] The segmented sintering process of the zirconia crown preform includes the following steps:

[0096] The zirconia crown blank was heated from room temperature to 52°C at a rate of 1.2°C / min and held at 52°C for 25 min; from 52°C to 105°C at a rate of 9.2°C / min; from 105°C to 310°C at a rate of 3.2°C / min; from 310°C to 590°C at a rate of 2.2°C / min; and from 590°C to 1460°C at a rate of 0.7°C / min.

[0097] The inner bottom surface of the microstructure crown has several grooves; the cross-section of the groove at the joint is hexagonal.

[0098] The density of the microstructured crown is 6.03 g / cm³. 3 It has a density of over 98%, a strength of 810 MPa, and a coefficient of thermal expansion ≤ 10.5*10. -6 / K, fracture toughness is 8.2 MPa·m1 / 2 .

[0099] Example 3:

[0100] The contents that are the same as in Example 1 will not be repeated here; the different aspects of this embodiment compared to Example 1 are as follows:

[0101] This embodiment provides a method for manufacturing a microstructured dental crown using waste zirconium blocks, wherein the waste zirconium powder preparation process includes:

[0102] The grinding equipment contains grinding balls with diameters of 10mm, 25mm, and 50mm in a ratio of 2:2:5. The grinding speed is 245r / min, with a 3min stop every 26min, and the grinding time is 34h.

[0103] The waste zirconium powder raw material was kept at 620°C for 3.8 hours.

[0104] The mass ratio of the waste zirconium powder raw material, solvent, and additives is 53:53:1; the mass ratio of the waste zirconium powder raw material to the grinding balls during grinding is 53:100, the grinding time is 46 hours, and the particle D50 of the obtained powder slurry is 460 nm.

[0105] The solvent is methanol or ethanol; the additive is castor oil or polyacrylic acid.

[0106] The resin slurry comprises UV inhibitor, polymeric monomer, and initiator in a mass ratio of 0.65:100:1;

[0107] The UV inhibitor includes ferrous aminosulfonate and ferrous fluoride; the initiator includes triarylthionium salt;

[0108] The polymeric monomers include a first polymeric monomer and a second polymeric monomer in a mass ratio of 32:63;

[0109] The first polymerization monomer includes 1,4-cyclohexyldiethanol divinyl ether and tripropylene glycol diacrylate; the second polymerization monomer includes pentaerythritol triacrylate.

[0110] The mass ratio of the powder slurry, resin slurry, and dispersant is 3:200:85;

[0111] The segmented sintering process of the zirconia crown preform includes the following steps:

[0112] The zirconia crown blank was heated from room temperature to 68°C at a rate of 3.6°C / min and held at 68°C for 15 min; from 68°C to 115°C at a rate of 9.8°C / min; from 115°C to 350°C at a rate of 3.8°C / min; from 350°C to 610°C at a rate of 2.8°C / min; and from 610°C to 1510°C at a rate of 1.4°C / min.

[0113] The inner bottom surface of the microstructure crown is provided with several grooves; the cross-section of the groove is one of pentagon, hexagon, or octagon.

[0114] The density of the microstructured crown is 6.05 g / cm³. 3 It has a density of over 99%, a strength of 855 MPa, and a coefficient of thermal expansion ≤ 8.5*10. -6 / K, fracture toughness is 9.5MPa·m1 / 2 .

[0115] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A method for manufacturing a microstructured dental crown using waste zirconium blocks, characterized in that, Includes the following steps: Waste zirconium blocks are used to prepare waste zirconium powder, wherein the waste zirconium powder includes zirconium oxide; Waste zirconium powder is obtained by removing iron from waste zirconium powder in a strong magnetic environment; Pre-calcining of waste zirconium powder raw materials; A photocurable slurry is prepared using the pre-calcined waste zirconium powder raw material, and the photocurable slurry includes a UV inhibitor; The zirconia crown preform is obtained by photocuring and printing using the aforementioned photocurable slurry. The zirconia crown blank is sintered in segments to obtain a microstructured crown; The inner bottom surface of the microstructure crown is provided with several grooves; the distance between the bottom surface of the groove and the outer occlusal surface of the opposite microstructure crown is not less than 0.8 mm.

2. The method for manufacturing microstructured dental crowns from waste zirconium blocks according to claim 1, characterized in that, The waste zirconium powder preparation process includes: The waste zirconium blocks are crushed and then screened to obtain waste zirconium powder by removing the material below a 100-mesh sieve. Preferably, the crushing equipment is a grinding equipment, which includes grinding balls with diameters of 10mm, 25mm, and 50mm in a ratio of (2-4):(2-4):(5-6), a grinding speed of 200-250 r / min, a stop of 3-5 minutes every 25-32 minutes, and a grinding time of 12-36 hours.

3. The method for manufacturing microstructured dental crowns from waste zirconium blocks according to claim 1, characterized in that, The pre-calcination process for waste zirconium powder raw materials involves holding the waste zirconium powder raw materials at 600-700℃ for 2-4 hours.

4. The method for manufacturing microstructured dental crowns from waste zirconium blocks according to claim 1, characterized in that, The preparation process of the photocurable slurry includes the following steps: Pre-calcined waste zirconium powder raw material, solvent, and additives are mixed and ground in proportion to obtain a powder slurry; A resin slurry is prepared, wherein the resin slurry comprises a UV inhibitor, a polymerizing monomer, and an initiator; The powder slurry, resin slurry, and dispersant are mixed evenly to obtain the light-curing slurry.

5. The method for manufacturing microstructured dental crowns from waste zirconium blocks according to claim 4, characterized in that, The mass ratio of the waste zirconium powder raw material, solvent, and additive is (45-55):(45-55):1; the mass ratio of the waste zirconium powder raw material to the grinding ball during grinding is (45-55):100, the grinding time is 24-48h, and the particle D50 of the obtained powder slurry is less than 500nm. The solvent is methanol or ethanol; the additive is castor oil or polyacrylic acid.

6. The method for manufacturing microstructured dental crowns from waste zirconium blocks according to claim 4, characterized in that, The resin slurry comprises UV inhibitor, polymerization monomer, and initiator in a mass ratio of (0.1-0.8):100:(1-3); The UV inhibitor, polymeric monomer, and initiator are mixed and then dispersed by ultrasonication to obtain a resin slurry.

7. The method for manufacturing microstructured dental crowns from waste zirconium blocks according to claim 6, characterized in that, The UV inhibitor includes one or more of ferrous aminosulfonate, ferrous titanate, and ferrous fluoride. The initiator includes one or more of triphenylthiofluoroborate, diaryliodomonium salt, and triarylthiomonium salt; The polymeric monomers include a first polymeric monomer and a second polymeric monomer in a mass ratio of (30-40):(60-70); The first polymerization monomer includes one or two of 1,4-cyclohexyldiethanol divinyl ether and tripropylene glycol diacrylate; The second polymerizable monomer includes one or more of trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, and pentaerythritol triacrylate.

8. The method for manufacturing microstructured dental crowns from waste zirconium blocks according to claim 4, characterized in that, The mass ratio of the powder slurry, resin slurry, and dispersant is (2-5):200:(80-100); The dispersant is an alkanoic ammonium salt of a block copolymer having acidic groups.

9. The method for manufacturing microstructured dental crowns from waste zirconium blocks according to claim 1, characterized in that, The segmented sintering process of the zirconia crown preform includes the following steps: The zirconia crown blank is heated from room temperature to 50-70℃ at a rate of 1-4℃ / min and held at 50-70℃ for 5-30 min; from 50-70℃ to 100-120℃ at a rate of 9-10℃ / min; from 100-120℃ to 300-360℃ at a rate of 3-4℃ / min; from 300-360℃ to 580-620℃ at a rate of 2-3℃ / min; and from 580-620℃ to 1450-1520℃ at a rate of 0.5-1.5℃ / min.

10. The method for manufacturing microstructured dental crowns from waste zirconium blocks according to claim 1, characterized in that, The groove includes a connecting groove and a limiting groove; the connecting groove contacts the inner side of the microstructured crown, and the end of the connecting groove away from the inner side of the microstructured crown is connected to the limiting groove; the minimum cross-sectional length of the connecting groove is greater than the cross-sectional length of the limiting groove. The cross-section of the groove of the joint is one of pentagon, hexagon, or octagon.

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