High-aesthetic simulated multilayer color zirconia porcelain block and preparation and sintering process thereof

Abstract

The application discloses high-aesthetic simulation multilayer color zirconia porcelain block and a preparation and sintering process thereof, relates to the technical field of zirconia porcelain block preparation, and comprises at least a cut end layer, a middle layer and a neck layer from top to bottom, wherein each layer has different color saturation and light transmittance. The zirconia porcelain block preparation system is arranged, the multilayer gradient structure design, the interface adhesion enhancement technology and the overall controllable dyeing process are used, the problems of poor aesthetic effect, easy interlayer cracking and poor color abrasion resistance of the existing zirconia porcelain block are solved, the prepared porcelain block has the realistic aesthetic effect of natural teeth and high-strength mechanical properties, is a high-performance dental restoration material with high clinical application value, and the zirconia porcelain block preparation and sintering data and corresponding analysis results are managed, visualized and stored, which is helpful to realize the zirconia porcelain block preparation and sintering management through the internet cloud management and control and improve the intelligent level of the zirconia porcelain block preparation and sintering management.

Description

Technical Field

[0001] This invention relates to the field of zirconia ceramic block preparation technology, specifically to high-aesthetic simulation multi-colored zirconia ceramic blocks and their preparation and sintering processes. Background Technology

[0002] Zirconia ceramics have become the mainstream material for all-ceramic dental restorations due to their excellent mechanical strength, fracture toughness, and biocompatibility. With increasing aesthetic demands, the translucency of zirconia restorations is becoming increasingly closer to that of natural teeth.-1 The aesthetic characteristic of natural teeth lies in the distinct gradient of their color and translucency: the incisal region is lighter in color and has higher translucency, the cervical region is darker in color and has lower translucency, and the intermediate region exhibits a natural transition. However, accurately simulating this gradient structure through material preparation processes remains a technical challenge in this field.

[0003] Chinese Patent Publication No. CN111848157A discloses a method for preparing zirconia ceramic blocks using a gel casting process, comprising: adding 1-5% by mass of acrylamide and methylenebisacrylamide powder to an aqueous solvent, and then adding 0.2-2% by mass of a dispersant powder to obtain a premix; adjusting the pH of the premix to 9-11, and then adding nano-zirconia powder to make the solid volume fraction of the slurry reach more than 50%; using a rotational viscometer to test the viscosity of the slurry to obtain a low-viscosity, high-solids-phase stable zirconia suspension slurry; sequentially adding 0.2 vol%-1 vol% of an initiator and 0.4 vol%-1 vol% of a catalyst to the stable suspension slurry and stirring evenly; injecting the obtained slurry into a pre-made mold, curing and demolding to obtain a wet blank; drying the wet blank to obtain a green body; and sintering to obtain a zirconia ceramic block. This method has the advantages of simple preparation process, good density of ceramic blocks, few defects in ceramic blocks, low organic content in ceramic blocks, high hardness and strength, and machinability. In addition, the instruments required for its preparation are simple and the mold cost is low.

[0004] The zirconia ceramic block technology mentioned above still has the following technical problems: Existing multilayer zirconia ceramic blocks mostly employ simple layering, resulting in significant differences in color and translucency between layers, abrupt transitions, and difficulty in mimicking the gradual change in color from the incisal edge to the cervical region of natural teeth. Some methods reduce translucency by applying a masking liquid throughout the restoration, but this fails to differentiate between the incisal and cervical areas, leading to uniform translucency and a single, untransparent color. A few foreign companies, such as Glidewell in the United States, use a slip-casting process, which can improve translucency, but the process is complex and difficult to achieve precise gradient control. Different colors and translucency of zirconia layers can easily generate interfacial stress during sintering due to inconsistent shrinkage rates, leading to interlayer cracking or delamination. The different sintering temperatures for the stable crystalline phases of ceramics of different colors make it difficult to simultaneously satisfy and guarantee the performance of multi-layered colors. Research shows that the inert surface chemistry of zirconia makes the durable adhesion of resin to zirconia a challenge. Some technologies require complex dyeing liquid penetration processes or multi-step dyeing treatments, resulting in long process flows, high control difficulty, and high production costs, thus causing many inconveniences.

[0005] Therefore, this invention requires the design of a high-aesthetic-value simulation multi-layered colored zirconia ceramic block and its preparation and sintering process to solve the above-mentioned problems. Summary of the Invention

[0006] The purpose of this invention is to provide a high-aesthetic simulation multi-layered colored zirconia ceramic block and its preparation and sintering process in order to solve the above problems. Through the synergistic technology of partitioned biomimetic dyeing, multi-layer gradient die casting and interface adhesive strengthening, a natural gradient of color and transparency from the cut end to the neck is achieved, while ensuring excellent interlayer bonding strength and mechanical properties.

[0007] To address the above problems, the present invention provides a technical solution: A high-aesthetic simulation multi-layered zirconia ceramic block, comprising at least a cut-end layer, a middle layer, and a neck layer from top to bottom, each layer having different color saturation and translucency, wherein: The cut-end layer has the lowest color saturation and the highest light transmittance; The neck layer has the highest color saturation and the lowest light transmittance; The intermediate layer has a color saturation and light transmittance that are between the cut-end layer and the neck layer, forming a natural transition.

[0008] In a preferred embodiment of the present invention, a zirconia adhesive layer is provided at the interface between the adjacent layers, and the thickness of the zirconia adhesive layer is 5-30 μm.

[0009] The preparation and sintering process of high-aesthetic simulation multi-colored zirconia ceramic blocks includes the following specific steps: S1. Prepare yttrium oxide stabilized zirconia nanoparticles, and then prepare regranulated particles by spray granulation; S2. Based on the physiological and anatomical characteristics of natural teeth, prepare staining solutions for the incisal region, the intermediate region, and the cervical region respectively. S3. Divide the basic zirconium oxide powder into at least three parts, and use the three dyeing solutions prepared in step 2 to perform partitioned immersion dyeing treatment. After drying, obtain zirconium oxide powder with different color numbers and chromaticities. S4. Using a layered die casting process, zirconium oxide powders of different color grades are laid in the mold in sequence from the neck to the cut end. Zirconia binder slurry is sprayed at the interface of adjacent layers and then pressed into shape. S5. The formed blank is degreased and pre-sintered to obtain a porous pre-sintered ceramic block. The pre-sintered ceramic block is then sintered to obtain a high-aesthetic simulation multi-layered color zirconia ceramic block.

[0010] In a preferred embodiment of the present invention, the zirconia adhesive layer comprises the following components: zirconia, yttrium oxide, bismuth oxide, zinc oxide, boron oxide, silicon dioxide, and magnesium oxide; The zirconia adhesive layer comprises the following components in weight percentage: 50-100 wt% zirconia, 5-10 wt% yttrium oxide, 0.6-5 wt% bismuth oxide, 0.5-5 wt% zinc oxide, 0.6-5 wt% boron oxide, 0.1-2 wt% silicon dioxide, and 0.5-4 wt% magnesium oxide.

[0011] In a preferred embodiment of the present invention, the biomimetic dyeing solution in step 2 comprises a masking component, a color component, and a transparency regulating component, with the following mass percentages: masking component 15-80 wt%, color component 19-84 wt%, and transparency regulating component 0-45 wt% and not 0. The color component contains soluble metal salts, including one or more of iron salts, cerium salts, praseodymium salts, erbium salts, and cobalt salts; the transparency regulating component includes one or more of soluble yttrium salts and soluble aluminum salts.

[0012] In a preferred embodiment of the present invention, the dyeing treatment in step 3 adopts an accelerator-assisted process: first, the zirconium oxide powder is fully soaked in the accelerator, and then added to the dyeing solution for immersion and dyeing.

[0013] In a preferred embodiment of the present invention, the pressing and molding in step 4 includes dry pressing and isostatic pressing, wherein the dry pressing pressure is not less than 10 MPa, the isostatic pressing pressure is 200-220 MPa, and the holding time is 5-15 min.

[0014] In a preferred embodiment of the present invention, the degreasing temperature in step 5 is 500-700℃, and the holding time is 1-4h; the pre-sintering temperature is 1000-1100℃, and the holding time is 1-3h; the final sintering temperature in step 5 is 1400-1550℃, and the holding time is 1-4h.

[0015] In a preferred embodiment of the present invention, a zirconia ceramic block preparation system needs to be constructed before proceeding to step S1. The zirconia ceramic block preparation system includes a powder preparation unit, a dyeing solution preparation unit, a dyeing treatment unit, a multilayer die casting unit, a sintering treatment unit, and a performance testing unit. The output terminals of the powder preparation unit, the dyeing solution preparation unit, the dyeing treatment unit, the multilayer die casting unit, and the sintering treatment unit are all communicatively connected to the input terminal of the performance testing unit.

[0016] In a preferred embodiment of the present invention, the powder preparation unit is used to prepare yttrium oxide-stabilized zirconium oxide nanopowder and perform spray granulation. The dyeing solution preparation unit is used to prepare biomimetic dyeing solutions for the cut end region, the middle region, and the neck region. The dyeing unit is used to perform zoned impregnation and dyeing treatment on the base powder. The multi-layer die-casting unit is used to lay out the dyed powder layers in sequence and spray an adhesive at the interface for pressing and molding. The sintering unit is used for degreasing, pre-sintering and final sintering of the green body; The performance testing unit is used to test the color parameters, light transmittance, and mechanical properties of the finished ceramic blocks.

[0017] The beneficial effects of this invention are as follows: This invention, through the establishment of a zirconia ceramic block preparation system, involves preparing yttrium-stabilized zirconia nanopowder, which is then spray-granulated into re-granulated particles. Based on the physiological and anatomical characteristics of natural teeth, staining solutions are prepared for the incisal region, intermediate region, and cervical region. The basic zirconia powder is divided into at least three portions, each treated with the three staining solutions prepared in step 2 for zonal impregnation and staining. After drying, zirconia powders of different shades are obtained. A layered die-casting process is used, where zirconia powders of different shades are sequentially laid in a mold from the cervical region to the incisal region. Zirconia adhesive slurry is sprayed at the interface between adjacent layers, and the mixture is pressed into shape. The formed blank is degreased and pre-sintered to obtain a porous pre-sintered ceramic block. The pre-sintered ceramic block is then finally sintered to obtain a high-aesthetic, simulated multi-layered zirconia ceramic block. Through multi-layer gradient structure design, interface bonding enhancement technology, and a controllable staining process, the problems of poor aesthetics, easy interlayer cracking, and poor wear resistance of existing zirconia blocks have been successfully solved. The prepared blocks combine the realistic aesthetics of natural teeth with high-strength mechanical properties, making them a high-performance dental restorative material with significant clinical application value. Furthermore, the outputs of all preceding units are connected to the performance testing unit, enabling full-process data traceability. This means that the performance testing unit can not only inspect the finished product but also comprehensively analyze data from each process stage, providing data support for continuous process optimization and ensuring product consistency. Managing, visualizing, and storing the zirconia block preparation and sintering data and corresponding analysis results facilitates the management of zirconia block preparation and sintering through internet cloud control, improving the level of intelligence in zirconia block preparation and sintering management. Attached Figure Description

[0018] For ease of explanation, the present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

[0019] Figure 1 This is an overall topological diagram of the high-aesthetic simulation multi-layered colored zirconia ceramic block of the present invention and its preparation and sintering process; Figure 2 This is a structural topology diagram of the zirconia ceramic block preparation system based on the high aesthetic simulation multi-layer color zirconia ceramic block and its preparation and sintering process of the present invention. Detailed Implementation

[0020] like Figure 1 and Figure 2 As shown, the specific implementation adopts the following technical solution: A high-aesthetic simulation multi-layered zirconia ceramic block, comprising at least a cut-end layer, a middle layer, and a neck layer from top to bottom, each layer having different color saturation and translucency, wherein: The cut-end layer has the lowest color saturation and the highest light transmittance; The neck layer has the highest color saturation and the lowest light transmittance; The intermediate layer has a color saturation and light transmittance that are between the cut-end layer and the neck layer, forming a natural transition.

[0021] In a preferred embodiment of the present invention, a zirconia adhesive layer is provided at the interface between the adjacent layers, and the thickness of the zirconia adhesive layer is 5-30 μm.

[0022] The preparation and sintering process of high-aesthetic simulation multi-colored zirconia ceramic blocks includes the following specific steps: S1. Prepare yttrium oxide stabilized zirconia nanoparticles, and then prepare regranulated particles by spray granulation; S2. Based on the physiological and anatomical characteristics of natural teeth, prepare staining solutions for the incisal region, the intermediate region, and the cervical region respectively. The biomimetic dyeing solution comprises a masking component, a color component, and a transparency regulating component, with the following mass percentages: masking component 15-80 wt%, color component 19-84 wt%, and transparency regulating component 0-45 wt% (not zero). The color component contains soluble metal salts, including one or more of iron salts, cerium salts, praseodymium salts, erbium salts, and cobalt salts. The transparency regulating component includes one or more of soluble yttrium salts and soluble aluminum salts. S3. Divide the basic zirconium oxide powder into at least three parts, and use the three dyeing solutions prepared in step 2 to perform partitioned immersion dyeing treatment. After drying, obtain zirconium oxide powder with different color numbers and chromaticities. The dyeing process employs an accelerator-assisted process: first, zirconium oxide powder is fully immersed in an accelerator, and then added to the dyeing solution for immersion and dyeing. S4. Using a layered die casting process, zirconium oxide powders of different color grades are laid in the mold in sequence from the neck to the cut end. Zirconia binder slurry is sprayed at the interface of adjacent layers and then pressed into shape. The pressing process includes dry pressing and isostatic pressing, wherein the dry pressing pressure is not less than 10 MPa, the isostatic pressing pressure is 200-220 MPa, and the holding time is 5-15 min. S5. The formed blank is degreased and pre-sintered to obtain a porous pre-sintered ceramic block. The pre-sintered ceramic block is then sintered to obtain a high-aesthetic simulation multi-layer color zirconia ceramic block. The degreasing temperature is 500-700℃, and the holding time is 1-4 hours; the pre-sintering temperature is 1000-1100℃, and the holding time is 1-3 hours; the final sintering temperature in step 5 is 1400-1550℃, and the holding time is 1-4 hours.

[0023] The zirconia adhesive layer comprises the following components: zirconia, yttrium oxide, bismuth oxide, zinc oxide, boron oxide, silicon dioxide, and magnesium oxide; The zirconia adhesive layer comprises the following components in weight percentage: 50-100 wt% zirconia, 5-10 wt% yttrium oxide, 0.6-5 wt% bismuth oxide, 0.5-5 wt% zinc oxide, 0.6-5 wt% boron oxide, 0.1-2 wt% silicon dioxide, and 0.5-4 wt% magnesium oxide.

[0024] Before proceeding to step S1, a zirconia ceramic block preparation system needs to be constructed. The zirconia ceramic block preparation system includes a powder preparation unit, a dyeing solution preparation unit, a dyeing treatment unit, a multilayer die casting unit, a sintering treatment unit, and a performance testing unit. The output terminals of the powder preparation unit, dyeing solution preparation unit, dyeing treatment unit, multilayer die casting unit, and sintering treatment unit are all communicatively connected to the input terminal of the performance testing unit.

[0025] The powder preparation unit is used to prepare yttrium oxide-stabilized zirconium oxide nanopowder and perform spray granulation. The dyeing solution preparation unit is used to prepare biomimetic dyeing solutions for the cut end region, the middle region, and the neck region. The dyeing unit is used to perform zoned impregnation and dyeing treatment on the base powder. The multi-layer die-casting unit is used to lay out the dyed powder layers in sequence and spray an adhesive at the interface for pressing and molding. The sintering unit is used for degreasing, pre-sintering and final sintering of the green body; The performance testing unit is used to test the color parameters, light transmittance, and mechanical properties of the finished ceramic blocks. Example 1: Three-layer zirconia ceramic block This embodiment provides a three-layer structure of aesthetically pleasing, multi-colored zirconia ceramic block and its preparation method.

[0026] In step 1, yttrium oxide-stabilized zirconia nanoparticles with a 5 mol% concentration were prepared using a co-precipitation method. The powder was dried in an oven at 80°C to a moisture content of 0.3%, and then spray-granulated to produce re-granulated particles with a particle size of 50 to 100 mesh, of which 78% were 50 to 60 mesh particles and 22% were 70 to 100 mesh particles. In step 2, three staining solutions were prepared according to the physiological and anatomical characteristics of natural teeth. The incisal region staining solution consisted of: 20% by weight of opaque component (nano-zirconia), 79% by weight of color component (containing 0.5% by weight of ferric nitrate and 0.2% by weight of cerium nitrate), and 1% by weight of translucency control component (yttrium nitrate). The intermediate region staining solution consisted of: 40% by weight of opaque component, 58% by weight of color component (containing 1.2% by weight of ferric nitrate and 0.5% by weight of cerium nitrate), and 2% by weight of translucency control component (yttrium nitrate). The cervical region staining solution consisted of: 65% by weight of opaque component, 34% by weight of color component (containing 2.5% by weight of ferric nitrate and 1.0% by weight of cerium nitrate), and 1% by weight of translucency control component (yttrium nitrate). In step 3, the zirconium oxide powder is first soaked in anhydrous ethanol as an accelerator for 30 minutes. Then, the base powder is divided into three equal parts and immersed in the three dyeing solutions mentioned above. The powder is ultrasonically dispersed for 30 minutes, allowed to stand for 2 hours, filtered, and dried at 80 degrees Celsius to a moisture content of 0.5% to obtain zirconium oxide powders with different color numbers and shades. In step 4, a layered die-casting process is used. In a 100mm diameter mold, 30g of bottom neck layer powder is laid and leveled, followed by a 20-micron thick layer of zirconia binder slurry. Another 30-micron thick layer of middle powder is then sprayed and leveled, and finally, a 20-micron thick layer of zirconia binder slurry is applied again. Finally, 30g of top cut-end powder is leveled. The zirconia binder formulation is: 82% wt% zirconia, 6% wt% yttrium oxide, 3% wt% bismuth oxide, 2.5% wt% zinc oxide, 2.5% wt% boron oxide, 2% wt% silicon dioxide, and 2% wt% magnesium oxide. Dry pressing is then performed at 15 MPa, followed by isostatic pressing at 210 MPa for 8 minutes. In step 5, the blank is placed in a sintering furnace and heated to 650 degrees Celsius at a heating rate of 2 degrees Celsius per minute, and held for 3 hours for degreasing. Then, it is heated to 1000 degrees Celsius at a heating rate of 5 degrees Celsius per minute and held for 2 hours for pre-sintering to obtain a porous pre-sintered ceramic block. The pre-sintered ceramic block is machined into a crown shape using CAD / CAM, and then heated to 1480 degrees Celsius at a heating rate of 5 degrees Celsius per minute and held for 3 hours for final sintering.

[0027] Performance testing results show the following: Regarding color parameters, the incisal layer has an L value of 82.5, an a value of 2.1, and a b value of 18.3; the intermediate layer has an L value of 75.4, an a value of 3.6, and a b value of 22.1; and the cervical layer has an L value of 68.3, an a value of 5.2, and a b value of 25.6. In terms of translucency, the incisal layer has 48%, the intermediate layer has 40%, and the cervical layer has 32%. The interlaminar bond strength reaches 52.3 MPa, the three-point flexural strength is 980 MPa, the fracture toughness is 6.2 MPa·m², and the sintering density is 6.05 g / cm³. The test results indicate that the color parameters exhibit a gradient change from the incisal edge to the cervical region, with a natural transition area without any visible boundary; the translucency gradually changes from 48% at the incisal edge to 32% at the cervical region, conforming to the distribution pattern of natural teeth; and both the interlaminar bond strength and the three-point flexural strength meet the requirements of ISO 6872 standard for dental ceramics. Example 2: Five-layer fine gradient structure zirconia ceramic block This embodiment is basically the same as embodiment 1, except that it adopts a five-layer structure: from top to bottom, it consists of a cut-end layer, a cut-end-intermediate transition layer, an intermediate layer, an intermediate-neck transition layer, and a neck layer, with a total of 4 layers of zirconia adhesive interfaces.

[0028] The staining solution formula was adjusted as follows: Cutting edge layer: 18% by weight of opaque component, 80% by weight of color component, and 2% by weight of transparency control component; Cutting edge-intermediate transition layer: 30% by weight of opaque component, 68% by weight of color component, and 2% by weight of transparency control component; Intermediate layer: 42% by weight of opaque component, 56% by weight of color component, and 2% by weight of transparency control component; Intermediate-neck transition layer: 54% by weight of opaque component, 44% by weight of color component, and 2% by weight of transparency control component; Neck layer: 66% by weight of opaque component, 32% by weight of color component, and 2% by weight of transparency control component. Performance testing results showed that the color continuity score was 9.6 out of 10, an improvement of 10.3% compared to 8.7 in Example 1; no delamination was visible to the naked eye; the interlayer bonding strength reached 54.1 MPa, an improvement of 3.4% compared to 52.3 MPa in Example 1; the three-point bending strength was 972 MPa, slightly lower than 980 MPa in Example 1, but the decrease was manageable; and the transmittance gradient continuity rating was excellent. The results indicate that the five-layer structure further improved the naturalness of the color transition, with no visible delamination, a significantly improved color continuity score, a slight increase in interlayer bonding strength, and stable mechanical properties. Comparative Example 1: Three-layer ceramic block without zirconium oxide adhesive layer This comparative example is basically the same as Example 1, except that in step 4, no zirconium oxide adhesive slurry is sprayed, and each layer of powder is directly pressed into shape. Performance testing results showed that the interlayer bonding strength of the sample without the zirconia binder layer was only 38.7 MPa, while the interlayer bonding strength of the sample in Example 1 with the binder layer reached 52.3 MPa, an improvement of 35.1% compared to the comparative example. Regarding the interfacial cracking rate after sintering, the comparative example reached 15%, while no interfacial cracking was observed in Example 1. In the three-point bending strength test, the comparative example reached 895 MPa, while Example 1 reached 980 MPa, an improvement of 9.5% compared to the comparative example. Cross-sectional analysis showed that the fracture of the comparative example sample mainly propagated along the interlayer interface, while the sample in Example 1 exhibited transgranular fracture characteristics. These results indicate that the zirconia binder layer plays a crucial role in improving the interfacial bonding strength of multilayer colored zirconia ceramic blocks. Comparative Example 2: Traditional single-layer stained zirconia ceramic block This comparative example uses a commercially available single-layer zirconia ceramic block (brand A), and simulates color gradients through a surface dyeing process. Performance testing results show that the color penetration depth of the comparative sample is only 50 to 80 micrometers, while Example 1 achieves overall gradient coloring. After 5000 washes, the comparative sample shows significant fading, while the sample in Example 1 shows no color change. The comparative sample does not form a transmittance gradient, while the sample in Example 1 exhibits a continuous transmittance gradient from the cut end to the neck. In the three-point bending strength test, the comparative sample reaches 950 MPa, while Example 1 reaches 980 MPa, an improvement of 3.2% compared to the comparative sample. These results indicate that traditional surface dyeing processes can only form a thin layer of color on the surface, have poor wear resistance, and cannot achieve an overall gradient change in transmittance, which is fundamentally different from the overall gradient dyeing technology of this invention.

[0029] The results showed that the five-layer structure further improved the naturalness of color transitions, with no layering visible to the naked eye, and a significant improvement in color continuity score. Interlayer bonding strength was slightly improved, while mechanical properties remained stable.

[0030] Those skilled in the art will recognize that the modules and method steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0031] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the devices, equipment, and modules described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0032] Furthermore, it should be noted that the combination of the various technical features in this case is not limited to the combination methods described in the claims of this case or the combination methods described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way, unless they contradict each other.

[0033] It should be noted that the above examples are merely specific embodiments of the present invention, and the present invention is obviously not limited to the above embodiments, with many similar variations. All modifications that can be directly derived or conceived by those skilled in the art from the content disclosed in this invention should fall within the protection scope of this invention.

[0034] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-aesthetic simulation multi-colored zirconia ceramic block, characterized in that, The ceramic block comprises at least a cut-end layer, a middle layer, and a neck layer from top to bottom, each layer having different color saturation and light transmittance, wherein: The cut-end layer has the lowest color saturation and the highest light transmittance; The neck layer has the highest color saturation and the lowest light transmittance; The intermediate layer has a color saturation and light transmittance that are between the cut-end layer and the neck layer, forming a natural transition.

2. The high-aesthetic simulation multi-colored zirconia ceramic block according to claim 1, characterized in that: A zirconia adhesive layer is provided at the interface between adjacent layers, and the thickness of the zirconia adhesive layer is 5-30 μm.

3. A preparation and sintering process for high-aesthetic simulation multi-colored zirconia ceramic blocks, used to implement the high-aesthetic simulation multi-colored zirconia ceramic blocks as described in any one of claims 1-2, characterized in that: The specific steps include the following: S1. Prepare yttrium oxide stabilized zirconia nanoparticles, and then prepare regranulated particles by spray granulation; S2. Based on the physiological and anatomical characteristics of natural teeth, prepare staining solutions for the incisal region, the intermediate region, and the cervical region respectively. S3. Divide the basic zirconium oxide powder into at least three parts, and use the three dyeing solutions prepared in step 2 to perform partitioned immersion dyeing treatment. After drying, obtain zirconium oxide powder with different color numbers and chromaticities. S4. Using a layered die casting process, zirconium oxide powders of different color grades are laid in the mold in sequence from the neck to the cut end. Zirconia binder slurry is sprayed at the interface of adjacent layers and then pressed into shape. S5. The formed blank is degreased and pre-sintered to obtain a porous pre-sintered ceramic block. The pre-sintered ceramic block is then sintered to obtain a high-aesthetic simulation multi-layered color zirconia ceramic block.

4. The preparation and sintering process of the high-aesthetic simulation multi-colored zirconia ceramic block according to claim 3, characterized in that: The zirconia adhesive layer comprises the following components: zirconia, yttrium oxide, bismuth oxide, zinc oxide, boron oxide, silicon dioxide, and magnesium oxide; The zirconia adhesive layer comprises the following components in weight percentage: 50-100 wt% zirconia, 5-10 wt% yttrium oxide, 0.6-5 wt% bismuth oxide, 0.5-5 wt% zinc oxide, 0.6-5 wt% boron oxide, 0.1-2 wt% silicon dioxide, and 0.5-4 wt% magnesium oxide.

5. The preparation and sintering process of the high-aesthetic simulation multi-colored zirconia ceramic block according to claim 3, characterized in that: The biomimetic dyeing solution in step 2 includes a masking component, a color component, and a transparency regulating component. The mass percentages of each component are as follows: masking component 15-80 wt%, color component 19-84 wt%, and transparency regulating component 0-45 wt% and not 0. The color component contains soluble metal salts, including one or more of iron salts, cerium salts, praseodymium salts, erbium salts, and cobalt salts. The transparency regulating component includes one or more of soluble yttrium salts and soluble aluminum salts.

6. The preparation and sintering process of the high-aesthetic simulation multi-colored zirconia ceramic block according to claim 5, characterized in that: The dyeing process in step 3 employs an accelerator-assisted process: first, zirconium oxide powder is fully immersed in an accelerator, and then added to the dyeing solution for immersion and dyeing.

7. The preparation and sintering process of the high-aesthetic simulation multi-colored zirconia ceramic block according to claim 5, characterized in that: The pressing process in step 4 includes dry pressing and isostatic pressing, wherein the dry pressing pressure is not less than 10 MPa, the isostatic pressing pressure is 200-220 MPa, and the holding time is 5-15 min.

8. The preparation and sintering process of the high-aesthetic simulation multi-colored zirconia ceramic block according to claim 5, characterized in that: The degreasing temperature in step 5 is 500-700℃, and the holding time is 1-4 hours; the pre-sintering temperature is 1000-1100℃, and the holding time is 1-3 hours; the final sintering temperature in step 5 is 1400-1550℃, and the holding time is 1-4 hours.

9. The high-aesthetic simulation multi-colored zirconia ceramic block according to claim 1, and its preparation and sintering process, characterized in that: Before proceeding to step S1, a zirconia ceramic block preparation system needs to be constructed. The zirconia ceramic block preparation system includes a powder preparation unit, a dyeing solution preparation unit, a dyeing treatment unit, a multilayer die casting unit, a sintering treatment unit, and a performance testing unit. The output terminals of the powder preparation unit, dyeing solution preparation unit, dyeing treatment unit, multilayer die casting unit, and sintering treatment unit are all communicatively connected to the input terminal of the performance testing unit.

10. The high-aesthetic simulation multi-colored zirconia ceramic block according to claim 9, and its preparation and sintering process, characterized in that: The powder preparation unit is used to prepare yttrium oxide-stabilized zirconium oxide nanopowder and perform spray granulation. The dyeing solution preparation unit is used to prepare biomimetic dyeing solutions for the cut end region, the middle region, and the neck region. The dyeing unit is used to perform zoned impregnation and dyeing treatment on the base powder. The multi-layer die-casting unit is used to lay out the dyed powder layers in sequence and spray an adhesive at the interface for pressing and molding. The sintering unit is used for degreasing, pre-sintering and final sintering of the green body; The performance testing unit is used to test the color parameters, light transmittance, and mechanical properties of the finished ceramic blocks.

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