KR20240074206A - Multilayer gradation zirconia dental block having high strength and high permeability and manufacturing method thereof - Google Patents

Abstract

It relates to a multi-layer gradient zirconia dental block that can develop a color similar to natural teeth within 5 layers and a method of manufacturing the same. It consists of 5 layers, and each layer is made of mixed powder containing zirconia. By preparing the configuration, it can be processed similar to an actual tooth.

Description

Multilayer gradient zirconia dental block having high strength and high permeability and manufacturing method thereof {Multilayer gradation zirconia dental block having high strength and high permeability and manufacturing method thereof}

The present invention relates to a multilayer gradient zirconia dental block with high strength and high permeability and a manufacturing method thereof, and in particular to a multilayer gradient zirconia dental block capable of developing a color similar to natural teeth within 5 layers and a manufacturing method thereof. will be.

Recently, the technological development of artificial teeth is increasing day by day due to the development of medical technology. Artificial teeth are created by planting a biocompatible implant body in the jawbone that has been enlarged to sufficiently cover it, through additional surgeries such as bone grafting and bone lengthening, on the jawbone where there is a missing tooth or where a tooth was extracted. It is a dental treatment procedure that restores function.

Ceramic materials with excellent biocompatibility and light transparency are suitable as dental materials. Titanium or titanium alloy has been mainly used as a dental implant material, but zirconia, which has excellent mechanical properties, has recently been used in response to the demand for aesthetic treatment.

In addition, dental materials must be non-toxic in vivo, non-carcinogenic and mutagenic, and zirconia materials that are thermally, electrically and chemically stable in the oral environment are suitable.

In other words, dental dental block material must be non-toxic in vivo, non-carcinogenic and mutagenic, as well as thermally, electrically and chemically stable in the oral environment, aesthetics, color stability and low thermal conductivity. , it must have high resistance to corrosion and discoloration in the oral cavity, and must have excellent mechanical properties that can withstand not only normal loads repeated in the oral cavity but also abnormal loads such as teeth clenching.

As a dental dental block material, zirconia material has chemical resistance against alkali and is attracting attention as a next-generation dental artificial tooth prosthetic material due to its excellent material properties such as low thermal expansion, high strength, high hardness, and friction resistance.

These zirconia materials have limitations in accurately reproducing the same color and transparency as natural teeth, and porcelain is generally layered on top of zirconia to compensate for the limitations in aesthetics.

An example of this technology is disclosed in Patent Documents 1 to 3 below.

For example, in Patent Document 1 below, (S1) forming a zirconia powder layer with a flat surface by pouring zirconia powder into a molding mold, (S2) firing the zirconia powder on the zirconia powder layer. Adding zirconia powder with different shades and then forming a zirconia powder layer, (S3) repeating the step (S2) 1 to 10 times to form a multi-layered zirconia powder layer, (S4) forming the powder layer A method for manufacturing a zirconia block is disclosed, including the step of pressing and (S5) forming a molded body by pressing the powder layer by cold isostatic pressing (CIP) molding.

In addition, in Patent Document 2 below, the main material preparation step of preparing ceramic powder, which is the main material for manufacturing dental prosthesis, by color, the main material melting step of melting ceramic powder of each color using an electric furnace, and the order of darkest color among the melted ceramic powders. A prosthesis forming step in which the mold is injected into a mold and then pressed with a press to form it into the shape of a dental prosthesis; a first heat treatment step in which impurities are removed by heating the molded dental prosthesis with high temperature heat; and heat is applied to the first heat treated dental prosthesis. A method of manufacturing an artificial tooth prosthesis using a ceramic ingot for pressure casting with a color gradient consisting of a secondary heat treatment step to improve durability and appearance is disclosed.

On the other hand, in Patent Document 3 below, a plurality of zirconia powders containing zirconia and a stabilizer that suppresses phase transition of zirconia are formed, and the plurality of zirconia powders are stacked to form a zirconia composition, and the zirconia composition is formed. It is a zirconia calcined body manufactured by firing at 800°C to 1200°C, and when the zirconia calcined body is manufactured by laminating zirconia powders with different compositions, a zirconia sintered body with high dimensional accuracy can be obtained.

Republic of Korea Patent Publication No. 2017-0023436 (published on March 6, 2017) Republic of Korea Patent Publication No. 10-1815125 (registered on December 28, 2017) Japanese Patent Publication No. 2018-30775 (published on March 1, 2018)

In the technology disclosed in Patent Document 1 as described above, a zirconia block having a gradation similar to that of natural teeth was prepared, but there was a limit to showing a color similar to that of natural teeth, and there was a problem that multiple layers were required to achieve this. .

In addition, Patent Document 2 discloses a manufacturing method in which a plurality of zirconia powders of different colors are melted, pressed, and then subjected to a heat treatment process. However, when manufacturing teeth with a pressure press, there is a disadvantage that reprocessing is required due to surface roughness.

Meanwhile, Patent Document 3 discloses a method for producing a powder containing zirconia particles and a pigment, but there was a problem in that the pigment was added to the raw material and it was difficult to achieve a color close to natural teeth with the color of the raw material itself.

That is, in the conventional technology as described above, uneven density occurs due to coarsening in the pre-sintered state, the degree of coarsening occurs significantly in some high-density parts inside the block, and uneven coarsening causes non-uniformity in the hardness of the block. This causes excessive wear of the processing and block breakage during manufacturing, bending at the final sintering stage, high risk of breakage due to internal stress, and price competitiveness due to reduced yield of the final product after processing due to the risk of breakage. There was a problem with it falling. In addition, in the case of low-strength products, damage occurs during implant use, and the aesthetic effect is reduced by thickly processing the end of the tooth, which should be transparent, to prevent damage.

The purpose of the present invention is to solve the problems described above. Since the interior has a uniform network structure, CAD/CAM processing is easy, and due to the uniform density, it becomes isotropic during final sintering, resulting in a uniform mesh structure. To provide a shrinkable multi-layer gradient zirconia dental block and a manufacturing method thereof.

Another object of the present invention is to provide a multi-layer gradient zirconia dental block and a manufacturing method thereof that can minimize the defect rate during the heat treatment process at the customer site and increase the yield of the final product due to processing stability.

Another object of the present invention is to provide a multi-layer gradient zirconia dental block that has high resistance to breakage due to high strength and can have a longer lifespan compared to existing products, and a method of manufacturing the same.

In order to achieve the above object, the multilayer gradient zirconia dental block according to the present invention is a multilayer gradient zirconia dental block that can develop a color similar to natural teeth, and is composed of five layers, each layer containing zirconia. It is characterized by being made of mixed powder.

In addition, in the multilayer gradient zirconia dental block according to the present invention, the mixed powder includes 5YSZ (Yttria Stabilized Zirconia) white, 4YSZ yellow, and 3YSZ pink.

In addition, in the multilayer gradient zirconia dental block according to the present invention, the 5YSZ white includes ZrO ₂ , HfO ₂ , Y ₂ O ₃ , and Al ₂ O ₃ , and the 4YSZ yellow includes ZrO ₂ , HfO ₂ , Y ₂ O ₃ , It contains Al ₂ O ₃ and Fe ₂ O ₃ , and the 3YSZ pink is characterized by containing ZrO ₂ , HfO ₂ , Er ₂ O ₃ , and Al ₂ O ₃ .

In addition, in the multi-layer gradient zirconia dental block according to the present invention, the first to fifth layers are sequentially and evenly stacked from the bottom of the five layers, and the first layer is 5YSZ white 60 wt%, 4YSZ yellow 36 wt%, It consists of 3YSZ pink 4 wt%, the second layer consists of 5YSZ white 61 wt%, 4YSZ yellow 34 wt%, 3YSZ pink 5 wt%, and the third layer consists of 5YSZ white 64 wt%, 4YSZ yellow 32 wt %, 3YSZ pink 4 wt%, the fourth layer consists of 5YSZ white 70 wt%, 4YSZ yellow 27 wt%, 3YSZ pink 3 wt%, and the fifth layer consists of 5YSZ white 82 wt%, 4YSZ yellow It is characterized by being composed of 17 wt% and 3YSZ pink 1 wt%.

In addition, in the multi-layer gradient zirconia dental block according to the present invention, the first to fifth layers of the five layers are stacked sequentially and evenly from the bottom, and the first layer is prepared at 20 wt% based on 100 wt% of the dental block. The second layer is prepared at 20 wt% based on 100 wt% of the dental block, the third layer is prepared at 17 wt% based on 100 wt% of the dental block, and the fourth layer is prepared at 100 wt% of the dental block. It is provided at 18 wt% for, and the fifth layer is provided at 25 wt% for 100 wt% of dental block.

In addition, in order to achieve the above object, the method of manufacturing a multilayer gradient zirconia dental block according to the present invention is a method of manufacturing a multilayer gradient zirconia dental block that can develop a color similar to natural teeth, including (a) a plurality of raw material powders Preparing, (b) mixing a plurality of raw powders prepared in step (a), (c) stacking the mixed powder prepared in step (b) into 5 layers and forming a laminate, (d) It is characterized in that it includes the step of performing cold isostatic pressing (CIP) on the laminate by preforming, and (e) pre-sintering the five-layer laminate on which CIP was performed in step (d).

In addition, in the method of manufacturing a multilayer gradient zirconia dental block according to the present invention, the mixed powder prepared in step (b) includes 5YSZ (Yttria Stabilized Zirconia) white, 4YSZ yellow, and 3YSZ pink, and the cold isostatic press is pressed at a pressure of 130 MPa. It is characterized by being executed as.

As described above, according to the multi-layer gradient zirconia dental block and its manufacturing method according to the present invention, sufficient strength can be secured even when the tip of the tooth is processed to a thinner thickness, making it possible to process it more similar to an actual tooth. The effect that can be achieved is achieved.

In addition, according to the multilayer gradient zirconia dental block and its manufacturing method according to the present invention, the higher the light transmittance, the more transparent the tip (end of the tooth), like an actual tooth, can be processed, thereby increasing the aesthetic effect. The effect that can be achieved is achieved.

Meanwhile, according to the multilayer gradient zirconia dental block and its manufacturing method according to the present invention, a multilayer gradient zirconia dental block capable of reproducing the color tone of natural teeth can be produced using raw materials with various molar concentrations, and separate coloring work is not required. It is easy to use and has the effect of maximizing the aesthetic effect.

In addition, according to the multilayer gradient zirconia dental block and its manufacturing method according to the present invention, the gradient dental block can be used without separate coloring, has high versatility, can prevent stains caused by colorants, and has a high level of experience and By simplifying the coloring work, which is a process that requires accumulated know-how, the effect of being free from manpower and time constraints is also achieved.

1 is a process diagram illustrating the manufacturing process of a multilayer gradient zirconia dental block according to the present invention;
Figure 2 is a FE-SEM image of the size (a) and shape (b) of the physical properties of zirconia powder particles as raw material powder;
Figure 3 is a graph of XRD patterns of raw material powder and mixed powder;
Figure 4 is a graph showing the XRD pattern of powder (-powder) and sintered body (-bulk);
5 is a graph showing a pre-sintering schedule for manufacturing a multilayer gradient zirconia dental block with strength and high permeability according to the present invention;
Figure 6 is a sintering state temperature graph for the pre-sintering step shown in Figure 1;
Figure 7 is a diagram showing the experimental results of sintering shown in Figure 6;
Figure 8 is a diagram for explaining the sintering mechanism of a zirconia dental block;
Figure 9 is a HR-SEM image of the fracture surface of the zirconia dental block 001 sample;
Figure 10 is a graph showing the results of measuring the thermal expansion coefficient of a zirconia dental block sample from room temperature to 500°C according to the present invention;
Figure 11 is a diagram showing the process (b) of putting the prepared raw material powder (a) into the mixer and discharging it;
12 is a photograph showing the state of mixed powder according to mixing time;
Figure 13 is a diagram showing the height change according to pressure during uniaxial pressure molding;
Figure 14 is a diagram for explaining sintering furnace temperature verification using measuring;
Figure 15 is a graph showing the TG-DTA measurement results of zirconia dental block raw material powder;
Figure 16 is a photograph to explain the manufacturing process of a multi-layer gradient dental block molded body;
Figure 17 is a diagram showing the raw material weight ratio and shade for each layer in the zirconia layered structure;
18 is a photograph of a multilayer gradient zirconia dental block manufactured according to the present invention.

The above and other objects and new features of the present invention will become more clear by the description of this specification and the accompanying drawings.

The term “dental block” used herein refers to zirconia powder prepared by grinding and processed into a block by pressing it with a press, and is also called a dental blank. In addition, these dental blocks are individually provided in a variety of colors by adding different coloring agents to the powder material. Accordingly, the block of the color most similar to the color of each patient's teeth is selected to provide a patient-customized crown. can do.

In addition, zirconia applied to the present invention is an oxide (ZrO ₂ ) of the metal element zirconium (Zr), and can be manufactured using natural monoclinic zirconia (baddeleyite) or zircon (ZrSiO ₄ ) as a raw material. You can. Zirconia is a white solid at room temperature and has a high melting point, so it is used as a heat-resistant material. As the temperature increases, pure zirconia exists in a monoclinic phase up to 1,170℃, a tetragonal phase from 1,170℃ to 2,370℃, and a cubic phase from above temperatures up to its melting point of 2,680℃. When lowered, phase transformation occurs again into cubic, tetragonal, and monoclinic phases.

Hereinafter, a method for manufacturing a multilayer gradient zirconia dental block with high strength and high permeability according to the present invention will be described with reference to FIG. 1.

Figure 1 is a process diagram for explaining the manufacturing process of a multi-layer gradient zirconia dental block according to the present invention.

As shown in Figure 1, the multi-layer gradient zirconia dental block according to the present invention is prepared by grinding various materials to a certain size according to each characteristic and processing them into powder form to prepare a plurality of raw powders (S10), 5 A plurality of raw material powders prepared in step S10 are mixed to form a layered dental block (S20).

Next, a plurality of mixed powders are stacked in 5 layers and molded into a laminate (S30), and the laminate is cold isostatically pressed by powder preforming before additional densification by sintering or hot isostatic pressing (HIP). Execute (CIP) (S40).

Next, the five-layer laminate on which CIP was performed is pre-sintered (S50) and processed (S60), and then the quality is checked (S70) to complete the dental block according to the present invention.

As shown in Figure 2, which shows the size and shape of the physical properties of the zirconia powder particles, the powder in step S10 has a FE-SEM test analysis particle size of 0.1 nm to 0.3 nm, and the size of the sphere produced through a spray dryer is Available in sizes from 20㎛ to 60㎛. Figure 2 is a FE-SEM image of the size (a) and shape (b) of the physical properties of zirconia powder particles as raw material powder.

In addition, the monoclinic phase fraction of the raw material powder was analyzed.

The raw material powder used in the present invention may include 5YSZ (Yttria Stabilized Zirconia) white, 4YSZ yellow, and 3YSZ pink, and the monoclinic phase fraction of this raw material powder and the mixed powder prepared in step S20 was measured using XRD (X-ray Diffraction). ) was confirmed through analysis. This mixed powder was measured after running a wet ball-mill for 24 hours and sufficiently drying at 80°C for more than 48 hours.

Table 1 below shows the expected composition ratio of 5YSZ White, 4YSZ Yellow, and 3YSZ Pink as the mixed powder to be used in the present invention.

As shown in Figure 3, as a result of XRD measurement at 40 kV, 100 mA, and 4 degrees per minute, monoclinic baddeleyite and tetragonal ZrO ₂ phases were found in the raw material powder and mixed powder. Figure 3 is a graph of XRD patterns of raw material powder and mixed powder.

In addition, when calculating the ratio of monoclinic (-111) peak, (111) peak, and tetragonal (111) peak, the monoclinic phase fraction of 5YSZ, 4YSZ, and 3YSZ raw material powders are 4%, 36%, respectively, as shown in Table 2. It was 52%, and it was found that the higher the proportion of 5YSZ in the mixed powder, the lower the monoclinic phase fraction.

Table 2 shows the monoclinic phase fraction of the raw powder and mixed powder to be used in the present invention.

In addition, as a result of sintering the 5YSZ and mixed powder (9-1-0) sample at 1,500°C for 4 hours, it was confirmed that the baddeleyite phase with a monoclinic structure disappeared, as shown in Figure 4. Therefore, the monoclinic phase fraction was able to achieve the final goal of 0%, and the final result was confirmed through XRD analysis of the multilayer gradient dental block.

Figure 4 is a graph showing the XRD pattern of powder (-powder) and sintered body (-bulk). Also, the powder (-powder) and sintered (-bulk) monoclinic phase fractions were as shown in Table 3.

In addition, a base raw material mixture was prepared to optimize the physical properties to be applied in step S20.

First, a mixture of base raw materials was prepared.

That is, as the mixed powder to be applied in step S20, zirconia powder (White) was prepared as shown in Table 4, zirconia powder (Yellow) was prepared as shown in Table 5, and zirconia powder (Pink) was prepared as shown in Table 6. .

In order to manufacture a zirconia dental block according to the present invention, it is necessary to secure uniform density. As a molding element technology for this, uniform density was secured through secondary molding (isostatic pressure molding), and molding conditions were established by varying pressures to match the shrinkage rate.

In other words, as a heat treatment element technology to secure high strength, a sintering schedule was established after selecting a pre-sintering schedule. Figure 5 is a graph showing a pre-sintering schedule for manufacturing a multilayer gradient zirconia dental block with strength and high permeability according to the present invention.

Table 7 below shows the experimental results until the pre-sintering schedule was established.

Additionally, the sintering schedule is shown in Figure 6, and the experimental results until the sintering schedule was established are shown in Figure 7. Figure 6 is a sintering state temperature graph for the pre-sintering step shown in Figure 1, and Figure 7 is a diagram showing the experimental results of sintering shown in Figure 6. As shown in Figures 6 and 7, it was found that the final temperature for sintering was preferably 1,560°C or higher.

In addition, in order to manufacture the multilayer gradient zirconia dental block according to the present invention, the correlation between molding and heat treatment process conditions for raw material powder was tested.

As shown in Figure 8, when the raw material is agglomerated through molding of the raw material powder and partially liquefied on the surface of the powder through heat treatment, the surface area decreases, neck formation occurs, and the powders combine to become one. Figure 8 is a diagram for explaining the sintering mechanism of a zirconia dental block.

In addition, to evaluate the zirconia dental block sample according to the present invention, the microstructure, crystal phase, and thermal expansion coefficient of the sample for each process were evaluated.

To evaluate the microstructure of the zirconia dental block 001 sample, the fracture surface of the 001 sample was confirmed through HR-SEM (scanning electron microscopy) measurement. As shown in Figure 9, it was confirmed that the zirconia dental block was a high-density sintered body with nanocrystal grains and no pores. Figure 9 is a HR-SEM image of the fracture surface of the zirconia dental block 001 sample.

Additionally, to evaluate the thermal expansion coefficient, the thermal expansion coefficient of the zirconia dental block 001 sample sintered body was measured in the range from room temperature to 500°C. As shown in Figure 10, the measurement result showed that 80% of the final goal was achieved with 8.004 (10 ^-6 K ^-1 ). Figure 10 is a graph showing the results of measuring the thermal expansion coefficient of a zirconia dental block sample according to the present invention from room temperature to 500°C.

Meanwhile, the bending strength, sintered body density, and light transmittance of the zirconia dental block sample according to the present invention were evaluated.

The bending strength of the Zirconia Dental Block 001 sample exceeded the final target value with an average of 1,047 MPa, and in the case of a multi-layer gradient dental block, the strength of layers with different mixing ratios can be considered. In addition, the sintered body density of the zirconia dental block 001 sample was 6.03 g/cm ³ on average, and uniformity between dental blocks was also excellent. The final goal of the main performance indicator is the density of the compact after CIP, and considering the shrinkage rate of the sintered compact, it was judged that multilayer gradient dental block specimens could also be sufficiently achieved. The light transmittance test to ensure the aesthetics of the multilayer gradient dental block is closely related to the bending strength, and the zirconia dental block 001 sample had a high bending strength of 1,047 MPa, while the light transmittance was low at an average of 8.6%. Multi-layer gradient dental block can control strength and light transmittance depending on the mixing ratio.

The results of the bending strength, sintered body density, and light transmittance analysis as described above are shown in Table 8.

In addition, in step S30, optimization of the mixing ratio of zirconia raw materials for each shade to prepare the laminate was prepared. First, the shade uniformity according to the mixing ratio of raw materials was explored to establish the ratio of each shade of raw material mixing.

The raw powder mixing ratio for each shade is shown in Table 9.

An example of the mixing process of raw materials is shown in Figure 11. Figure 11 is a diagram showing the process (b) of inserting and discharging the prepared raw material powder (a) into the mixer.

In addition, as a result of exploring the uniformity of the raw material composition ratio for each mixing time, as shown in FIG. 12, the mixing state was the same for 1 hour and more than 1 hour when the mixing state was confirmed in time units. Figure 12 is a photograph showing the state of mixed powder according to mixing time.

In addition, as a process optimization for manufacturing the multi-layer gradient zirconia dental block according to the present invention, the process was established through controlling the first and second forming process variables according to steps S40 and S50.

As a result of research on molding pressure and holding time during the first molding (uniaxial pressure molding), the research results were obtained when the pressure during molding was varied and the holding time (no change even if the time was increased by more than 10 seconds) was the same (production is the best). (based on the most common 14T product) is shown in Figure 13. Figure 13 is a diagram showing the height change according to pressure during uniaxial pressure molding. In other words, the appropriate product dimensions could be confirmed according to Figure 13.

In order to establish the desired dimensions and uniform density during secondary molding (isostatic pressure molding), the pressure during molding was varied and shown in Table 10.

Table 10 shows dimensional changes according to pressure changes during isostatic pressure forming.

As described above, the dimensions and pressure for preparing the multilayer gradient zirconia dental block according to the present invention could be determined according to Figure 13 and Table 10.

In addition, in order to measure temperature and confirm shrinkage after pre-sintering of the multilayer gradient zirconia dental block, the temperature was measured using measuring (PTCR-ETH-071 measurement), as shown in FIG. 14. Figure 14 is a diagram for explaining sintering furnace temperature verification using measuring.

Additionally, the shrinkage confirmation results after pre-sintering are shown in Table 11. Table 11 shows the results of measuring the shrinkage rate of the presintered body.

Meanwhile, the pre-sintering (calcining) conditions for removing organic impurities during the heat treatment process were checked for complete degreasing through TG-DTA weight difference analysis after degreasing.

As shown in Figure 15, it was confirmed that impurities were removed between 200°C and above to 400°C. Figure 15 is a graph showing the TG-DTA measurement results of zirconia dental block raw material powder.

In addition, as we reviewed the pre-sintering conditions to improve cutting processing efficiency, we were able to establish schedule conditions for finding the most ideal pre-sintering state under the conditions shown in FIG. 5.

In addition, the mixing ratio of the raw materials for the multi-layer gradient zirconia block without shrinkage cracks during multi-layer heterogeneous powder molding was tested. Each layer of the ratio test was molded to be level. Figure 16 is a photograph to explain the manufacturing process of a multi-layer gradient dental block molded body.

Meanwhile, in the present invention, the raw material mixing ratio was established in the zirconia layered structure in order to establish the raw material mixing ratio and the raw material weight ratio for each layer with different yttria contents.

Table 12 shows the raw material powder mixing ratio for each zirconia stack and shade.

Figure 17 is a diagram showing the raw material weight ratio and shade for each layer in a zirconia layered structure, and Figure 18 is a photograph of a multi-layer gradient zirconia dental block manufactured according to the present invention.

As shown in Figure 18, the multi-layer gradient zirconia dental block manufactured according to the present invention does not require separate coloring work, so it is easy to use and can maximize the aesthetic effect.

Although the invention made by the present inventor has been described in detail according to the above-mentioned embodiments, the present invention is not limited to the above-described embodiments and can of course be changed in various ways without departing from the gist of the invention.

By using the multilayer gradient zirconia dental block and its manufacturing method according to the present invention, sufficient strength can be secured even when the tip of the tooth is processed to a thinner thickness, making it possible to process it more similar to an actual tooth.

Claims (10)

A multi-layer gradient zirconia dental block that can develop colors similar to natural teeth,
A multi-layer gradient zirconia dental block consisting of 5 layers, where each layer is made of mixed powder containing zirconia. In paragraph 1:
The mixed powder is a multi-layer gradient zirconia dental block comprising 5YSZ (Yttria Stabilized Zirconia) white, 4YSZ yellow, and 3YSZ pink. In paragraph 2,
The 5YSZ white includes ZrO ₂ , HfO ₂ , Y ₂ O ₃ , Al ₂ O ₃ ,
The 4YSZ yellow includes ZrO ₂ , HfO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , Fe ₂ O ₃ ,
The 3YSZ pink is a multilayer gradient zirconia dental block comprising ZrO ₂ , HfO ₂ , Er ₂ O ₃ , and Al ₂ O ₃ . In paragraph 3,
In the five layers, the first to fifth layers are stacked sequentially and evenly from the bottom,
The first layer consists of 5YSZ white 60 wt%, 4YSZ yellow 36 wt%, and 3YSZ pink 4 wt%,
The second layer consists of 5YSZ white 61 wt%, 4YSZ yellow 34 wt%, and 3YSZ pink 5 wt%,
The third layer consists of 5YSZ white 64 wt%, 4YSZ yellow 32 wt%, and 3YSZ pink 4 wt%,
The fourth layer consists of 5YSZ white 70 wt%, 4YSZ yellow 27 wt%, and 3YSZ pink 3 wt%,
The fifth layer is a multi-layer gradient zirconia dental block, characterized in that it consists of 5YSZ white 82 wt%, 4YSZ yellow 17 wt%, and 3YSZ pink 1 wt%. In paragraph 3,
In the five layers, the first to fifth layers are stacked sequentially and evenly from the bottom,
The first layer is prepared at 20 wt% for 100 wt% of dental block,
The second layer is prepared at 20 wt% for 100 wt% of dental block,
The third layer is prepared at 17 wt% for 100 wt% of dental block,
The fourth layer is prepared at 18 wt% for 100 wt% of dental block,
The fifth layer is a multi-layered gradient zirconia dental block, characterized in that it is provided at 25 wt% based on 100 wt% of the dental block. A method of manufacturing a multilayer gradient zirconia dental block that can develop a color similar to natural teeth,
(a) preparing a plurality of raw material powders,
(b) mixing a plurality of raw material powders prepared in step (a),
(c) stacking the mixed powder prepared in step (b) into 5 layers and forming a laminate,
(d) performing a preform cold isostatic press (CIP) on the laminate;
(e) A method of manufacturing a multilayer gradient zirconia dental block, comprising the step of pre-sintering the five-layer laminate on which CIP was performed in step (d). In paragraph 6:
The mixed powder prepared in step (b) includes 5YSZ (Yttria Stabilized Zirconia) white, 4YSZ yellow, and 3YSZ pink,
A method of manufacturing a multilayer gradient zirconia dental block, characterized in that the cold isostatic press is performed at a pressure of 130 MPa. In paragraph 7:
The 5YSZ white includes ZrO ₂ , HfO ₂ , Y ₂ O ₃ , Al ₂ O ₃ ,
The 4YSZ yellow includes ZrO ₂ , HfO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , Fe ₂ O ₃ ,
The 3YSZ pink is a method of manufacturing a multilayer gradient zirconia dental block, characterized in that it contains ZrO ₂ , HfO ₂ , Er ₂ O ₃ , and Al ₂ O ₃ . In paragraph 6:
In the five layers, the first to fifth layers are stacked sequentially and evenly from the bottom,
The first layer consists of 5YSZ white 60 wt%, 4YSZ yellow 36 wt%, and 3YSZ pink 4 wt%,
The second layer consists of 5YSZ white 61 wt%, 4YSZ yellow 34 wt%, and 3YSZ pink 5 wt%,
The third layer consists of 5YSZ white 64 wt%, 4YSZ yellow 32 wt%, and 3YSZ pink 4 wt%,
The fourth layer consists of 5YSZ white 70 wt%, 4YSZ yellow 27 wt%, and 3YSZ pink 3 wt%,
A method of manufacturing a multi-layer gradient zirconia dental block, characterized in that the fifth layer consists of 5YSZ white 82 wt%, 4YSZ yellow 17 wt%, and 3YSZ pink 1 wt%. In paragraph 6:
In the five layers, the first to fifth layers are stacked sequentially and evenly from the bottom,
The first layer is prepared at 20 wt% for 100 wt% of dental block,
The second layer is prepared at 20 wt% for 100 wt% of dental block,
The third layer is prepared at 17 wt% for 100 wt% of dental block,
The fourth layer is prepared at 18 wt% for 100 wt% of dental block,
A method of manufacturing a multilayer gradient zirconia dental block, characterized in that the fifth layer is provided at 25 wt% based on 100 wt% of the dental block.