Zirconia workpiece for dental cutting and its manufacturing method, transparency improving liquid for zirconia workpiece for dental cutting and its use method

Abstract

To provide a completely sintered zirconia body that does not cause deformation and that, while maintaining high strength, has more exceptional light transmissivity and more exceptional tonal saturation compared to zirconia cutting objects for dental cutting produced from zirconia raw material powder containing various stabilizers.SOLUTION: A zirconia cutting object for dental cutting of the present invention is a semi-baked zirconia cutting object for dental cutting containing semi-baked ceramic particles, and the zirconia cutting object for dental cutting comprises zirconium oxide, a stabilizer formed from an oxide, and a water-soluble compound salt that is not an oxide and contains at least one element selected from calcium, magnesium, and rare earth elements. The amount of the stabilizer in the semi-fired ceramic particles is 2 to 7 mol%, and the amount of the water-soluble compound salt in the zirconia cutting object for dental cutting is 0.1 to 3.5 mol%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims priority based on Japanese Patent Application No. 2017-29797 filed with the Japan Patent Office on February 21, 2017, Japanese Patent Application No. 2017-71954 filed with the Japan Patent Office on March 31, 2017, and Japanese Patent Application No. 2017-242860 filed with the Japan Patent Office on December 19, 2017, the contents of which are incorporated herein in their entirety for all purposes. The present invention relates to a zirconia workpiece for dental cutting and a method for producing the same, as well as a transparency improving liquid for a zirconia workpiece for dental cutting and a method for using the same. [Background technology]

[0002] Traditionally, dental treatment for crown defects has generally involved prosthetic restoration using cast crowns and bridges or dentures. Specifically, clinical applications of porcelain-fused-to-bridges include porcelain fused to the surface of a metal frame made from a casting alloy for porcelain fusion, which replicates the shape of a tooth crown.

[0003] On the other hand, from the viewpoint of the risk of developing metal allergies, rising prices due to fluctuations in the market prices of precious metals, and aesthetics that can mimic the color tone of natural teeth, attention has been drawn to prosthetic devices made by techniques such as the dipping method using alumina, aluminosilicate glass, lithium disilicate glass, etc., or the pressing method using ceramic ingots, known as all-ceramics.

[0004] In recent years, the technology of fabricating prosthetic devices by machining using dental CAD / CAM systems has rapidly become widespread. This has made it possible to easily fabricate prosthetic devices by machining workpieces such as blanks, including blocks and disks, made from zirconia, alumina, aluminosilicate glass, and lithium disilicate glass.

[0005] In particular, zirconia has high strength and is therefore used clinically in a variety of cases. Fully sintered zirconia (hereinafter also referred to as "fully sintered zirconia" in this specification) is too hard to be machined using a dental CAD / CAM system. Therefore, for dental cutting, so-called pre-sintered zirconia cutting bodies are used, which are not fully sintered but are pre-fired at a low firing temperature to adjust the hardness to a level that allows cutting.

[0006] A typical zirconia cutting body for dental cutting is manufactured by molding zirconia raw material powder by press molding or the like, and then calcining it at about 800 to 1200°C.

[0007] The properties of the zirconia workpiece for dental cutting, that is, the properties of the fully sintered zirconia body, are affected by the properties of the zirconia raw material powder used.

[0008] For example, Patent Document 1 discloses a fully sintered zirconia body produced from a zirconia blank (body to be cut) for dental cutting using a zirconia raw material powder containing 3 mol% yttrium. Because the sintered body has high strength, it has been used clinically in bridge frames with four or more units. However, because the sintered body has low translucency, it has been difficult to reproduce a color similar to that of natural teeth.

[0009] Patent Document 2 discloses a fully sintered zirconia body produced from a zirconia blank for dental cutting using a zirconia raw material powder containing 3 mol% yttrium with a reduced alumina content. Because this sintered body maintains high strength while improving translucency, it has been used clinically in long-span bridges with four or more units and full crowns in the molar region. However, because the translucency of this sintered body is insufficient, it has been difficult to apply it to cases requiring high aesthetics, such as the anterior teeth.

[0010] Patent Document 3 discloses a fully sintered zirconia body produced from a zirconia blank for dental cutting, prepared using a zirconia raw material powder containing 4 to 6.5 mol% yttrium. Because the sintered body has high translucency, it has been used in cases where high aesthetics are required, such as in the anterior teeth. However, although the sintered body has high translucency, its low strength makes it difficult to apply to long-span bridges with four or more units, and the incisal edge is prone to fracture.

[0011] Thus, a fully sintered zirconia body produced using a zirconia raw material powder containing 4 to 6.5 mol% yttrium has high translucency but low strength. On the other hand, a fully sintered zirconia body produced using a zirconia raw material powder containing 3 mol% yttrium has high strength but low translucency. Therefore, the properties of the fully sintered zirconia body depend on the yttrium content of the zirconia raw material powder, and there is a trade-off between translucency and strength.

[0012] To address these issues, dental cutting zirconia blanks made by layering zirconia raw material powders with different yttrium contents have been put to clinical use, with the aim of achieving both the translucency required to reproduce the incisal edge of natural teeth and the high strength required for long-span bridges of four or more units.

[0013] Patent Document 4 discloses a method for manufacturing a zirconia blank for dental cutting, in which a zirconia raw material powder containing 5 mol% yttrium is layered on the incisal edge side and a zirconia raw material powder containing 3 mol% yttrium is layered on the cervical side. A fully sintered zirconia body produced from this zirconia blank has translucency suitable for the incisal edge and high strength in the cervical region. However, this sintered body has a problem in that it deforms in long-span bridges and the like due to differences in thermal expansion between the layers, resulting in poor fit of the long-span bridge.

[0014] Patent Document 5 discloses a fully sintered zirconia body produced from a zirconia blank for dental cutting, which is prepared by laminating a zirconia raw material powder containing 6 to 10 wt% yttrium on the incisal edge side and a zirconia raw material powder containing 4.5 to 6 wt% yttrium on the cervical side. The sintered body has translucency suitable for the incisal edge and high strength in the cervical area, where strength is required for long-span bridges. However, even with this sintered body, there are problems such as deformation occurring in long-span bridges, etc., due to differences in thermal expansion between the layers, which results in poor fit of the long-span bridge, and the incisal edge with a high yttrium content being prone to fracture.

[0015] As described above, conventional zirconia cutting objects for dental cutting have not been able to provide a fully sintered zirconia body that maintains high strength, has excellent translucency and color saturation, and is free from deformation.

[0016] Furthermore, prosthetic devices fabricated by machining do not require uniform transparency throughout. Specifically, while the tip of the enamel is particularly required to be transparent, as with natural teeth, the cervical area does not require transparency in order to avoid adversely affecting the color of the prosthetic device, as the abutment tooth on which the prosthetic device is placed may be a discolored tooth or metal. In other words, if the cervical area is too transparent, the crown color may not be the desired shade. Therefore, there was a need to fabricate an aesthetic prosthetic device in which only the enamel area is highly transparent, while the transparency decreases as you move toward the cervical area.

[0017] In order to solve these problems, various liquids have been applied to a zirconia workpiece for dental cutting or a zirconia sintered body in order to impart a color reproduction similar to that of natural teeth to the zirconia sintered body.

[0018] For example, Patent Document 6 discloses a method for color-matching a prosthetic device, in which a prosthetic device is fabricated by cutting pre-sintered zirconia for dental cutting, and then a metal ion or metal complex solution is applied to the prosthetic device and sintered. This method reproduces the color tone of teeth in a prosthetic device fabricated by cutting pre-sintered zirconia for dental cutting, but fails to improve transparency and saturation.

[0019] Patent Document 7 discloses a technique for facilitating the penetration of a coloring liquid into pre-sintered dental cutting zirconia by specifying the range of the BET specific surface area of ​​the zirconia. However, this method was not able to improve the transparency and saturation of the surface of the prosthetic device produced by cutting.

[0020] Patent Document 8 discloses a solution technology for coloring pre-sintered zirconia for dental cutting. This technology does not use water as a solvent, which reduces contamination of the firing furnace caused by acid and is said to have excellent coloring performance. However, although this method has the ability to color prosthetic devices, it is unable to improve the transparency and saturation of the surface layer.

[0021] Although Patent Documents 5 to 8 disclose techniques for improving the transparency and coloring of zirconia prosthetic devices machined using a CAD / CAM system, these prior art techniques have not been able to improve the transparency without reducing the strength of the high-strength zirconia prosthetic device. Therefore, there is a demand for a fully sintered zirconia body that maintains high strength, has excellent translucency and excellent color saturation, and is free from deformation. [Prior art documents] [Patent documents]

[0022] [Patent Document 1] Japanese Patent Application Publication No. 60-235762 [Patent Document 2] Patent No. 5608976 [Patent Document 3] International Publication No. 2015 / 199018 [Patent Document 4] US Patent Application Publication No. 2016 / 354186 [Patent Document 5] US Patent Application Publication No. 2017 / 245970 [Patent Document 6] Special Publication No. 2002-536280 [Patent Document 7] Special Publication No. 2015-536904 [Patent Document 8] Special Publication No. 2013-529599 Summary of the Invention [Problem to be solved by the invention]

[0023] An object of the present invention is to provide a fully sintered zirconia body that maintains high strength, has superior translucency and color saturation compared to zirconia bodies for dental cutting produced from zirconia raw material powders containing various stabilizers, and is free from deformation. [Means for solving the problem]

[0024] To solve the above problems, the present inventors conducted extensive research into a zirconia object for dental cutting that can provide a fully sintered zirconia body having better translucency and color saturation than conventional zirconia objects for dental cutting produced from zirconia raw material powders containing various stabilizers. As a result, they found that by incorporating a specific amount of a water-soluble compound salt that is not an oxide and contains calcium, magnesium, or a rare earth element such as yttrium or lanthanum, along with a specific amount of a stabilizer consisting of an oxide, the fully sintered zirconia body produced from the zirconia object for dental cutting can be provided with a high strength, a translucency and color saturation that are better than conventional zirconia objects for dental cutting produced from zirconia raw material powders containing various stabilizers, and a fully sintered zirconia body that does not deform. The present invention is based on this finding.

[0025] The present invention is as follows. The present invention provides a zirconia object for dental cutting, which is cut to produce a prosthetic device, the zirconia object for dental cutting being a semi-sintered zirconia object for dental cutting comprising a semi-sintered body of ceramic particles, the zirconia object for dental cutting comprising zirconium oxide, a stabilizer comprising an oxide, and a water-soluble compound salt that is not an oxide and contains at least one element selected from calcium, magnesium, and rare earth elements, the amount of the stabilizer in the semi-sintered body of ceramic particles being 2 to 7 mol% and the amount of the water-soluble compound salt in the zirconia object for dental cutting being 0.1 to 3.5 mol%. The zirconia object for dental cutting of the present invention preferably comprises zirconium oxide, a stabilizer comprising an oxide, and a water-soluble compound salt.

[0026] In the zirconia workpiece for dental cutting of the present invention, the water-soluble compound salt preferably contains yttrium.

[0027] In the zirconia cutting body for dental cutting of the present invention, it is preferable that the semi-sintered ceramic particles contain the zirconium oxide and a stabilizer made of the oxide, and that the water-soluble compound salt is supported on the surface of the semi-sintered ceramic particles.

[0028] In this case, the zirconia workpiece for dental cutting of the present invention preferably has a water-soluble compound salt content at a position that is 45 to 55% of the distance from the surface of the workpiece for dental cutting toward the center of gravity of the workpiece for dental cutting from the surface to the center of gravity of the workpiece for dental cutting, and that is 50 to 150% of the water-soluble compound salt content at a position that is 10 to 20% of the distance from the surface of the workpiece for dental cutting toward the center of gravity of the workpiece for dental cutting from the surface to the center of gravity of the workpiece for dental cutting.

[0029] In the zirconia workpiece for dental cutting of the present invention, the semi-sintered ceramic particles preferably contain the zirconium oxide, a stabilizer made of the oxide, and the water-soluble compound salt.

[0030] The zirconia workpiece for dental cutting of the present invention preferably contains Pr, Er, Fe, Co, Ni, Mn or Cu as a coloring material.

[0031] In this case, the zirconia workpiece for dental cutting of the present invention preferably comprises a plurality of layers each having a different content of the stabilizer made of the oxide and / or the colorant.

[0032] The zirconia workpiece for dental cutting of the present invention is preferably in the shape of a disk or a block.

[0033] The present invention also provides a dental prosthetic device made from the zirconia workpiece for dental cutting of the present invention.

[0034] The present invention also provides a method for producing a zirconia workpiece for dental cutting, the method comprising the following steps (1) and / or (2): (1) A step of semi-firing ceramic particles containing zirconium oxide, 2 to 7 mol% of a stabilizer made of an oxide, and 0.1 to 3.5 mol% of a water-soluble compound salt that is not an oxide and contains at least one element selected from calcium, magnesium, and rare earth elements. (2) A process of semi-firing ceramic particles containing zirconium oxide and a stabilizer consisting of 2 to 7 mol% of an oxide, and impregnating a zirconia workpiece for dental cutting containing the semi-firing ceramic particles with a water-soluble compound salt solution that is not an oxide and that contains at least one element selected from calcium, magnesium, and rare earth elements.

[0035] When the method for producing a zirconia workpiece for dental cutting of the present invention includes the step (2), the zirconia workpiece for dental cutting containing the semi-sintered ceramic particles is preferably dried after being impregnated with the water-soluble compound salt solution.

[0036] When the method of the present invention for producing a zirconia workpiece for dental cutting includes the step (2), the water-soluble compound salt solution preferably contains a water-soluble cerium compound.

[0037] When the method of the present invention for producing a zirconia workpiece for dental cutting includes the step (2), the water-soluble compound salt solution preferably contains a water-soluble cerium compound, vegetable oil, and an organic solvent.

[0038] The present invention also provides a method for manufacturing a dental prosthetic device from a zirconia object for dental cutting, which is produced by the method for manufacturing a zirconia object for dental cutting including the step (2) above, in which the zirconia object for dental cutting is dry-cut into the shape of the dental prosthetic device and then fired.

[0039] The present invention also provides a method for manufacturing a dental prosthetic device from a zirconia object for dental cutting, which is produced by the method for manufacturing a zirconia object for dental cutting including the step (1) above, wherein the zirconia object for dental cutting is cut into the shape of the dental prosthetic device and then fired.

[0040] The present invention also provides a transparency improving liquid containing the water-soluble compound salt solution for producing the zirconia workpiece for dental cutting of the present invention or for producing the dental prosthetic device of the present invention, the transparency improving liquid containing (a) 10 to 80 wt% of a water-soluble compound salt solution that is not an oxide (excluding cerium compounds), and (b) 20 to 90 wt% of water.

[0041] The present invention also provides a transparency improving liquid containing the water-soluble compound salt solution for producing the zirconia workpiece for dental cutting of the present invention or for producing the dental prosthetic device of the present invention, the transparency improving liquid containing: (a) 10 to 80 wt% of a water-soluble compound salt solution that is not an oxide (excluding cerium compounds); (b) 8 to 86 wt% of water; and (c) 2 to 80 wt% of a water-soluble cerium compound.

[0042] The present invention also provides a transparency improving liquid containing the water-soluble compound salt solution for producing the zirconia workpiece for dental cutting of the present invention or for producing the dental prosthetic device of the present invention, the transparency improving liquid containing: (a) 10 to 80 wt% of a water-soluble compound salt solution that is not an oxide (excluding cerium compounds); (b) 8 to 86 wt% of water and / or vegetable oil; (c) 2 to 80 wt% of a water-soluble cerium compound; and (d) 0.1 to 20 wt% of a water-soluble organic solvent.

[0043] In this case, in the transparency improving liquid of the present invention, (d) the water-soluble organic solvent is preferably any one of alcohols, polyols, and glycol ethers.

[0044] In this case, the transparency improving liquid of the present invention preferably contains 30 to 70 wt % in total of (a) a solution of a water-soluble compound salt that is not an oxide (excluding cerium compounds) and (c) a water-soluble cerium compound.

[0045] The present invention also provides a method for using the transparency improving liquid of the present invention, in which a zirconia workpiece for dental cutting is coated with or immersed in the transparency improving liquid, thereby causing a water-soluble compound salt that is not an oxide to be supported on the surface of the semi-sintered ceramic particle body.

[0046] In the method for using the transparency improving liquid of the present invention, the zirconia workpiece for dental cutting preferably contains iron.

[0047] In the method for using the transparency improving liquid of the present invention, the zirconia workpiece for dental cutting preferably contains yttrium and / or erbium.

[0048] In this case, in the method for using the transparency improving liquid of the present invention, the zirconia workpiece for dental cutting preferably has a molar concentration of yttrium and / or erbium of 4 mol % or less.

[0049] In the method for using the transparency improving liquid of the present invention, it is preferable to apply the transparency improving liquid only to the surface layer of the dental prosthetic device cut from the zirconia workpiece for dental cutting.

[0050] In this case, in the method of using the transparency improving liquid of the present invention, the dental prosthetic device is preferably an inlay, laminate, crown or bridge. [Effects of the Invention]

[0051] According to the present invention, it is possible to provide a fully sintered zirconia body that maintains high strength, has superior translucency and color saturation to those of a zirconia body for dental cutting produced from a zirconia raw material powder containing various stabilizers, and is free from deformation. DETAILED DESCRIPTION OF THE INVENTION

[0052] Hereinafter, embodiments of the present invention will be described in detail by way of example. The zirconia object for dental cutting of the present invention is a zirconia object for dental cutting to be machined to produce a prosthetic device, the zirconia object for dental cutting being a semi-sintered zirconia object for dental cutting comprising a semi-sintered body (calcined body / pre-sintered body) of ceramic particles, the zirconia object for dental cutting comprising zirconium oxide, a stabilizer consisting of an oxide (hereinafter simply referred to as the "stabilizer"), and a non-oxide water-soluble compound salt containing at least one element selected from calcium, magnesium, and rare earth elements (hereinafter simply referred to as the "water-soluble compound salt"), the amount of the stabilizer in the semi-sintered body of ceramic particles being 2 to 7 mol%, and the amount of the water-soluble compound salt in the zirconia object for dental cutting being 0.1 to 3.5 mol%. The prosthetic device of the present invention is a device produced by machining the zirconia object for dental cutting, and includes both semi-sintered bodies and fully sintered bodies. In this case, the zirconia workpiece for dental cutting contains 89.5 to 97.9 mol % of zirconium oxide.

[0053] The zirconia workpiece for dental cutting of the present invention can be produced using a known zirconia raw material powder. Specifically, for example, the zirconia workpiece for dental cutting of the present invention can be produced from a zirconia raw material powder containing a stabilizer. Furthermore, the stabilizer contained in the zirconia workpiece for dental cutting preferably contains yttrium and / or erbium.

[0054] In the zirconia workpiece for dental cutting of the present invention, the amount of stabilizer in the semi-sintered ceramic particles contained in the zirconia workpiece for dental cutting is 2 to 7 mol%. In other words, in the present invention, 2 to 7 mol% of the semi-sintered ceramic particles is composed of a stabilizer made of an oxide. If the amount of stabilizer made of an oxide in the semi-sintered ceramic particles is less than 2 mol%, the fully sintered zirconia body cannot be imparted with sufficient translucency. On the other hand, if the amount of stabilizer made of an oxide in the semi-sintered ceramic particles exceeds 7 mol%, the fully sintered zirconia body will have improved translucency, but it will be difficult to impart sufficient strength. In the present invention, the stabilizer content refers to the ratio (amount of stabilizer) / (total inorganic oxides contained in the semi-sintered ceramic particles) expressed in mol%.

[0055] In the zirconia object for dental cutting of the present invention, the amount of water-soluble compound salt in the zirconia object for dental cutting is 0.1 to 3.5 mol%. In other words, in the present invention, 0.1 to 3.5 mol% of the zirconia object for dental cutting is composed of water-soluble compound salt. Preferably, the amount of water-soluble compound salt is 0.5 to 3.0 mol%. In the present invention, the content of water-soluble compound salt refers to the ratio (amount of water-soluble compound salt) / (total inorganic oxides contained in the zirconia object for dental cutting) expressed in mol%.

[0056] If the content of the water-soluble compound salt in the zirconia object for dental cutting of the present invention is less than 0.1 mol%, the zirconia object for dental cutting cannot be imparted with sufficient translucency. On the other hand, if it exceeds 3.5 mol%, the translucency of the fully sintered zirconia body is improved, but it becomes difficult to impart sufficient strength. In the present invention, the water-soluble compound salt preferably contains yttria. By including yttria in the water-soluble compound salt, the translucency can be further improved.

[0057] The zirconia workpiece for dental cutting of the present invention is preferably produced using a colored zirconia raw material powder. Specifically, examples include yellow zirconia raw material powder containing iron and red zirconia raw material powder containing erbium as a stabilizer. Furthermore, in addition to these colored zirconia raw material powders, colored zirconia raw material powders containing elements such as praseodymium, cobalt, nickel, manganese, chromium, and copper can be used in combination to adjust the color tone without any problems. By incorporating these colorants, it is possible to achieve a color tone closer to that of natural teeth. Furthermore, for the purposes of improving sinterability and suppressing low-temperature degradation, it is preferable to produce the workpiece using a zirconia raw material powder containing 0.01 to 0.15 mol % of alumina (aluminum oxide) as a sintering aid. Using a zirconia raw material powder containing excessive alumina reduces the translucency of the fully sintered zirconia body.

[0058] The method for producing the zirconia cutting object for dental cutting of the present invention is not particularly limited, and it can be produced by, for example, a known production method. Specifically, it can be produced by press-molding a zirconia raw material powder. Furthermore, zirconia raw material powders with different compositions, particularly different contents of stabilizer and / or colorant, can be press-molded in multiple stages to form a multi-layered molding. Furthermore, the zirconia cutting object for dental cutting of the present invention is preferably one that has been subjected to CIP (cold isostatic pressing) treatment after press-molding. Furthermore, the zirconia cutting object for dental cutting of the present invention can be semi-fired (calcined / pre-sintered), for example, at 800 to 1200°C to adjust the hardness to a level suitable for cutting.

[0059] Next, a first embodiment of the zirconia workpiece for dental cutting of the present invention will be described. In the zirconia workpiece for dental cutting of the first embodiment, a semi-sintered body of ceramic particles contains zirconium oxide and a stabilizer made of an oxide, and a water-soluble compound salt is supported on the surface of the semi-sintered body of ceramic particles. The zirconia workpiece for dental cutting of the first embodiment is essentially composed of a semi-sintered body of ceramic particles.

[0060] Such zirconia cutting objects for dental cutting can be produced, for example, by semi-firing ceramic particles containing zirconium oxide as a zirconia raw material powder and 2-7 mol% of an oxide stabilizer, and then impregnating the semi-firing zirconia cutting object for dental cutting containing the semi-firing ceramic particles with a solution of a water-soluble compound salt that is not an oxide and contains at least one element selected from calcium, magnesium, and rare earth elements. In this case, the ceramic particles contain 93-98 mol% of zirconium oxide. More specifically, the semi-firing zirconia cutting object for dental cutting containing the semi-firing ceramic particles is immersed in a water-soluble compound salt solution containing the water-soluble compound salt and water, and then preferably dried, thereby supporting the water-soluble compound salt on the surfaces of the semi-firing ceramic particles contained in the zirconia cutting object for dental cutting. As used herein, the term "surface of the ceramic particle" refers not only to the outer surface of the ceramic particle but also to the inner surface of the ceramic particle that is connected to the outer surface of the ceramic particle. According to this manufacturing method, unlike conventional zirconia objects for dental cutting that are manufactured from zirconia raw material powder containing a predetermined amount of stabilizer, the zirconia object for dental cutting of the present invention can be manufactured by adding an arbitrary amount of water-soluble compound salt to the object for dental cutting after semi-firing of the ceramic particles. Therefore, a fully sintered zirconia body produced from the zirconia object for dental cutting manufactured in this manner can be manufactured to have superior translucency and color saturation compared to conventional zirconia objects for dental cutting while maintaining high strength, and can be imparted with the property of not causing deformation.

[0061] In the zirconia workpiece for dental cutting of this first embodiment, it is important that the water-soluble compound salt solution penetrates into the interior and that the water-soluble compound salt can be supported. To achieve this, the relative density and specific surface area of ​​the zirconia workpiece for dental cutting containing semi-sintered ceramic particles are important.

[0062] The relative density of the zirconia object for dental cutting according to the first embodiment is preferably 50 to 70%. A relative density of less than 50% is undesirable because the amount of water-soluble compound salt carried is insufficient, resulting in a desirable transparency when the object is sintered. On the other hand, a relative density of more than 70% is undesirable because the water-soluble compound salt solution does not penetrate sufficiently, resulting in a desirable transparency when the object is sintered. In this specification, the relative density of the zirconia object for dental cutting refers to the apparent density of the zirconia object for dental cutting, which is a semi-sintered body, when the density of a fully sintered body is taken as 100%.

[0063] The specific surface area of ​​the zirconia workpiece for dental cutting according to the first embodiment is 0.5 to 10 m 2 / g. The specific surface area is preferably 0.5m 2 If the specific surface area is less than 10 m / g, the water-soluble compound salt cannot be sufficiently supported, and transparency after sintering (complete sintering) of the workpiece cannot be obtained, which is not preferable. 2 If the amount exceeds 1 / g, the amount of the water-soluble compound salt carried becomes excessive, and the zirconia workpiece for dental cutting does not have sufficient transparency after sintering, which is not preferable.

[0064] The water-soluble compound salt solution used in the first embodiment contains a water-soluble compound that is not an oxide of at least one element selected from calcium, magnesium, or rare earth elements such as yttrium and lanthanum. Among these, it is preferable to use a water-soluble yttrium, calcium, magnesium, or lanthanum compound composed of a halide, nitrate, sulfate, or organic acid salt. Specific examples include yttrium chloride, calcium chloride, magnesium chloride, lanthanum chloride, yttrium nitrate, calcium nitrate, magnesium nitrate, lanthanum nitrate, yttrium acetate, yttrium carboxylate, calcium acetate, magnesium acetate, yttrium sulfate, calcium sulfate, and magnesium sulfate. Among these, water-soluble compounds of organic acid salts are particularly preferable from the viewpoint of preventing contamination of the firing furnace. Specific examples include yttrium acetate, yttrium carboxylate, calcium acetate, and magnesium acetate. These water-soluble compounds of at least one element selected from calcium, magnesium, or rare earth elements such as yttrium and lanthanum can be used alone or in combination.

[0065] The water-soluble compound salt solution used in the first embodiment preferably has a water-soluble compound salt content of 1 to 50 wt %, more preferably 5 to 30 wt %.

[0066] In the water-soluble compound salt solution used in the first embodiment, if the content of the water-soluble compound is less than 1 wt%, it is not preferable because the zirconia workpiece for dental cutting cannot be sufficiently supported with the water-soluble compound salt, whereas if it exceeds 50 wt%, it is not preferable because the solubility of the water-soluble compound salt is reduced.

[0067] The method for preparing the water-soluble compound salt solution used in the first embodiment is not particularly limited, and any preparation method will suffice as long as the water-soluble compound is dissolved in water.

[0068] In the present invention, the water-soluble compound salt solution may contain a water-soluble cerium compound, or may contain a water-soluble cerium compound, vegetable oil, and a water-soluble organic solvent.

[0069] The method for immersing the zirconia object for dental cutting according to the first embodiment in the water-soluble compound salt solution is not particularly limited as long as the water-soluble compound salt solution can penetrate into the gaps between the semi-sintered ceramic particles contained in the zirconia object for dental cutting. However, a simple and preferred method is to immerse the entirety and / or part of the zirconia object for dental cutting containing semi-sintered ceramic particles in the water-soluble compound salt solution. By immersing the entirety and / or part of the zirconia object for dental cutting containing semi-sintered ceramic particles, the water-soluble compound salt solution can gradually penetrate, by capillary action, into spaces inside the zirconia object for dental cutting that communicate with the outside of the zirconia object for dental cutting.

[0070] As a specific method for immersing the zirconia object for dental cutting according to the first embodiment in the water-soluble compound salt solution, it is preferable to immerse the zirconia object for dental cutting containing semi-sintered ceramic particles in the water-soluble compound salt solution in an amount of 1 to 100%, and more preferably 10 to 100%, of the total volume of the zirconia object for dental cutting containing semi-sintered ceramic particles. By controlling the volume of the water-soluble compound salt solution immersed in the zirconia object for dental cutting containing semi-sintered ceramic particles, the water-soluble compound salt can be supported only in desired portions of the zirconia object for dental cutting.

[0071] The specific atmosphere in which the zirconia object for dental cutting according to the first embodiment is immersed in the water-soluble compound salt solution is not particularly limited, and any of atmospheric pressure, reduced pressure, and pressurized atmospheres is acceptable. From the viewpoint of shortening the manufacturing time, placing the surrounding environment in a reduced pressure or pressurized atmosphere is preferable because it promotes penetration of the water-soluble compound salt solution. Furthermore, repeating the operation of reducing pressure and then returning to atmospheric pressure (reduced pressure / atmospheric pressure operation) or the operation of pressurizing and then returning to atmospheric pressure (pressurized / atmospheric pressure operation) multiple times is effective in shortening the time required for the process of infiltrating the water-soluble compound salt solution into the space inside the zirconia object for dental cutting that communicates with the outside of the object for dental cutting.

[0072] The time for immersing a zirconia workpiece for dental cutting containing semi-sintered ceramic particles in a water-soluble compound salt solution is not universally determined, but can be adjusted appropriately depending on the relative density and compact size of the zirconia workpiece for dental cutting containing semi-sintered ceramic particles, the degree of penetration of the water-soluble compound salt solution, the immersion method, etc. For example, the immersion time is usually 1 to 120 hours when immersing under reduced pressure, usually 0.5 to 12 hours, and usually 0.2 to 6 hours when contacting under pressure.

[0073] After the water-soluble compound salt solution has penetrated into the space inside the zirconia object for dental cutting that communicates with the outside of the object for dental cutting, the zirconia object for dental cutting is preferably removed from the water-soluble compound salt solution and the water-soluble compound salt solution is dried. The drying process is not particularly limited, but a simple and preferred method is drying under atmospheric pressure. The drying temperature is not particularly limited, but is preferably 100 to 500°C, more preferably 100 to 300°C. The drying time is also not particularly limited, but is usually 1 to 12 hours.

[0074] The zirconia object for dental cutting according to the first embodiment thus manufactured is cut to the desired size, ground, and surface polished as necessary before being shipped as a finished product. The zirconia object for dental cutting according to the first embodiment is subjected to a drying process after immersion in the water-soluble compound salt solution. Therefore, the zirconia object for dental cutting according to the first embodiment can be cut into the shape of a dental prosthetic device by dry cutting, and then sintered (fully sintered) to form a fully sintered body.

[0075] The method for producing a dental prosthetic device by completely sintering the zirconia workpiece for dental cutting according to the first embodiment after cutting is not particularly limited, but a simple and preferred method is firing at normal pressure. The firing temperature is not particularly limited, but is preferably 1400 to 1650°C, more preferably 1450 to 1600°C. The holding time at the maximum firing temperature is not particularly limited, but is preferably 2 to 12 hours, more preferably 2 to 4 hours. The temperature rise rate is not particularly limited, but is preferably 1 to 400°C / min, more preferably 3 to 100°C / min.

[0076] The zirconia cutting body for dental cutting according to the first embodiment can provide a fully sintered zirconia body that maintains high strength, has excellent translucency and color saturation, and is free from deformation, compared to zirconia cutting bodies for dental cutting manufactured from conventional zirconia raw material powders. While the reasons for these improvements are unclear, it is believed that by supporting a water-soluble compound salt capable of dissolving in zirconia on the outermost surface of the zirconia cutting body, the supported water-soluble compound salt segregates near the grain boundaries during post-sintering, promoting a phase transition (from tetragonal to cubic) of the crystalline phase near the grain boundaries, thereby improving translucency. Furthermore, supporting a water-soluble compound salt capable of dissolving in zirconia on the outermost surface of the zirconia cutting body is believed to reduce microcracks in the sintered body and improve the strength of the fully sintered zirconia body.

[0077] In the zirconia workpiece for dental cutting according to the first embodiment, the content of the water-soluble compound salt at a position 45 to 55% of the distance from the surface of the zirconia workpiece for dental cutting toward the center of gravity of the zirconia workpiece for dental cutting is preferably 50 to 150%, more preferably 70 to 130%, and most preferably 90 to 110%, of the content of the water-soluble compound salt at a position 10 to 20% of the distance from the surface of the zirconia workpiece for dental cutting toward the center of gravity of the zirconia workpiece for dental cutting. That is, the content of the water-soluble compound salt at a position 45-55% of the line segment from the surface to the center of gravity of the zirconia object for dental cutting is preferably 50-150% of the content of the water-soluble compound salt at a position 10-20% of the line segment from the surface. By satisfying this relationship, the water-soluble compound salt can be uniformly supported over the entire outermost surface of the zirconia object for dental cutting, thereby achieving the effects of improving translucency and strength uniformly over the entire zirconia fully sintered body. In this case, the surface position can be selected arbitrarily, as long as the above relationship is satisfied at any surface position. However, the above relationship is preferably satisfied when the surface position is the position where the dimension from the surface to the center of gravity of the zirconia object for dental cutting is the shortest. When the zirconia workpiece for dental cutting is block-shaped, the position of such a surface is the center of one of the surfaces of the block, and when the zirconia workpiece for dental cutting is disk-shaped, the position of such a surface is the center of a circular surface. Note that the position of the surface in the above relationship may also be the position where the dimension from the surface to the center of gravity of the zirconia workpiece for dental cutting is the longest.

[0078] The zirconia workpiece for dental cutting according to the first embodiment preferably contains Pr, Er, Fe, Co, Ni, or Cu as a coloring material, which allows the color to more closely resemble that of natural teeth.

[0079] In this case, the zirconia workpiece for dental cutting according to the first embodiment preferably comprises multiple layers each containing a different amount of stabilizer and / or colorant, which allows the color to more closely resemble that of natural teeth.

[0080] There are no particular limitations on the type of prosthetic device that can be machined using the zirconia object for dental cutting according to the first embodiment, and there is no problem with any prosthetic device, such as an inlay, laminate, crown, bridge, etc. Therefore, there are no particular limitations on the shape of the zirconia object for dental cutting from which a prosthetic device is cut, and any shape of zirconia object for dental cutting can be used, such as a block shape corresponding to an inlay, laminate, crown, etc., or a disk shape corresponding to a bridge.

[0081] Next, a second embodiment of the zirconia workpiece for dental cutting of the present invention will be described. In the second embodiment, the semi-sintered ceramic particles contain zirconium oxide, a stabilizer made of an oxide, and a water-soluble compound salt. The zirconia workpiece for dental cutting of the second embodiment is essentially composed of a semi-sintered ceramic particles.

[0082] Such a zirconia object for dental cutting can be produced, for example, by semi-firing ceramic particles containing zirconium oxide as a zirconia raw material powder, 2 to 7 mol% of a stabilizer composed of an oxide, and 0.1 to 3.5 mol% of a non-oxide water-soluble compound salt containing at least one element selected from calcium, magnesium, and rare earth elements. In the zirconia object for dental cutting produced in this manner, the stabilizer and water-soluble compound salt are contained in the zirconia object for dental cutting in a state in which they are entirely covered by the semi-firing ceramic particles. Therefore, in the zirconia object for dental cutting of the second embodiment, the water-soluble compound salt is not supported on the surface of the semi-firing ceramic particles. The fully sintered zirconia body produced from the zirconia object for dental cutting produced in this manner also contains sufficient stabilizer and water-soluble compound salt, thereby maintaining high strength and exhibiting superior translucency and color saturation compared to conventional zirconia objects for dental cutting, and exhibiting non-deformable properties.

[0083] The relative density and specific surface area of ​​the zirconia object for dental cutting according to the second embodiment can be approximately the same as those of the zirconia object for dental cutting according to the first embodiment. In this case, it can be impregnated with a water-soluble compound salt solution, as necessary, in the same way as the zirconia object for dental cutting according to the first embodiment.

[0084] The water-soluble compound salt used in the second embodiment can be a water-soluble compound that is not an oxide of at least one element selected from calcium, magnesium, or rare earth elements such as yttrium and lanthanum. Among these, it is preferable to use water-soluble yttrium, calcium, magnesium, and lanthanum compounds composed of halides, nitrates, sulfates, or organic acid salts. Specific examples include yttrium chloride, calcium chloride, magnesium chloride, lanthanum chloride, yttrium nitrate, calcium nitrate, magnesium nitrate, lanthanum nitrate, yttrium acetate, yttrium carboxylate, calcium acetate, magnesium acetate, yttrium sulfate, calcium sulfate, and magnesium sulfate. Among these, water-soluble compounds of organic acid salts are particularly preferable from the viewpoint of suppressing contamination of the firing furnace. Specific examples include yttrium acetate, yttrium carboxylate, calcium acetate, and magnesium acetate. These water-soluble compounds of at least one element selected from calcium, magnesium, or rare earth elements such as yttrium and lanthanum can be used alone or in combination.

[0085] The zirconia object for dental cutting according to the second embodiment manufactured in this manner is also cut to a desired size, machined, and surface polished as necessary before being shipped as a product. The zirconia object for dental cutting according to the second embodiment can be cut into the shape of a dental prosthetic device and then fired (fully sintered) to form a fully sintered body.

[0086] The zirconia workpiece for dental cutting according to the second embodiment can be fully sintered to produce a dental prosthetic device using the same method as the zirconia workpiece for dental cutting according to the first embodiment.

[0087] The zirconia workpiece for dental cutting according to the second embodiment also maintains high strength, while providing a fully sintered zirconia body that has excellent translucency and color saturation and is free from deformation, compared to zirconia workpieces for dental cutting produced from conventional zirconia raw material powders.

[0088] The zirconia workpiece for dental cutting according to the second embodiment also preferably contains Pr, Er, Fe, Co, Ni, or Cu as a coloring agent. In this case, the zirconia workpiece for dental cutting according to the second embodiment preferably comprises multiple layers with different stabilizer and / or coloring agent contents.

[0089] There are also no particular limitations on the type of prosthetic device that can be machined using the zirconia object for dental cutting according to the second embodiment, and there is no problem with any prosthetic device, such as an inlay, laminate, crown, bridge, etc. Therefore, there are no particular limitations on the shape of the zirconia object for dental cutting from which a prosthetic device is cut, and any shape of zirconia object for dental cutting can be used, such as a block shape corresponding to an inlay, laminate, crown, etc., or a disk shape corresponding to a bridge.

[0090] Next, a transparency improving liquid containing a water-soluble compound salt solution for producing a zirconia cutting body for dental cutting according to the present invention will be described. This transparency improving liquid can also be used to produce a dental prosthetic device. In a first embodiment of the transparency improving liquid according to the present invention, the transparency improving liquid contains 10 to 80 wt% of (a) a water-soluble compound salt solution that is not an oxide (excluding cerium compounds), and 20 to 90 wt% of (b) water. The transparency improving liquid of the first embodiment preferably contains 10 to 80 wt% of (a) a water-soluble compound salt solution (excluding cerium compounds), and 20 to 90 wt% of (b) water.

[0091] The water-soluble compound salt (not an oxide) of component (a) contained in the transparency improving liquid of the first embodiment is a water-soluble compound of at least one element selected from calcium, magnesium, or rare earth elements such as yttrium and lanthanum (excluding cerium compounds). Any water-soluble compound can be used regardless of its solubility, as long as it dissolves in water. Among these, it is preferable to use water-soluble compounds of rare earth elements such as yttrium, calcium, magnesium, and lanthanum, which are formed from halides, nitrates, sulfates, or organic acid salts. Specific examples include yttrium chloride, calcium chloride, magnesium chloride, lanthanum chloride, yttrium nitrate, calcium nitrate, magnesium nitrate, lanthanum nitrate, yttrium acetate, yttrium carboxylate, calcium acetate, magnesium acetate, yttrium sulfate, calcium sulfate, and magnesium sulfate. Of these, yttrium chloride and yttrium nitrate are particularly preferred. Furthermore, from the viewpoint of preventing contamination of the firing furnace, water-soluble compounds of organic acid salts are particularly preferred. Specific examples include yttrium acetate, yttrium carboxylate, calcium acetate, and magnesium acetate. These water-soluble compounds of at least one element selected from calcium, magnesium, or rare earth elements such as yttrium and lanthanum can be used alone or in combination. (Component (a): The content of the water-soluble compound that is not an oxide must be in the range of 10 wt% to 80 wt%, and more preferably in the range of 20 wt% to 60 wt%. If the content of the water-soluble compound salt in the transparency improving liquid is less than 10 wt%, for example, no improvement in transparency is observed when the transparency improving liquid is applied to a prosthetic device. On the other hand, if the content exceeds 80 wt%, the solubility in water is significantly reduced, making it impossible to prepare a uniform transparency improving liquid.

[0092] The (b) water contained in the transparency improving liquid of the first embodiment is necessary to dissolve or disperse the (a) water-soluble compound salt that is not an oxide. The water contained in the transparency improving liquid of the first embodiment is not particularly limited, but ion-exchanged water, purified water as specified in the Japanese Pharmacopoeia, distilled water as specified in the Japanese Pharmacopoeia, etc. can be used. The content of water contained in the transparency improving liquid of the first embodiment is in the range of 20 to 90 wt%, preferably in the range of 30 to 70 wt%. If the content is low, the solubility of the (a) water-soluble compound salt will be poor, and if the blending amount is high, the transparency improvement effect will be reduced.

[0093] The transparency improving liquid may contain 2 to 80 wt% of (c) a water-soluble cerium compound. In this case, the content of (b) water is in the range of 8 to 86 wt%. That is, in a second embodiment of the transparency improving liquid of the present invention, the transparency improving liquid contains 10 to 80 wt% of (a) a solution of a water-soluble compound salt that is not an oxide (excluding cerium compounds), 8 to 86 wt% of (b) water, and 2 to 80 wt% of (c) a water-soluble cerium compound.

[0094] The water-soluble cerium compound (component (c)) contained in the transparency improving liquid of the second embodiment can be any cerium compound, regardless of its solubility, as long as it dissolves in water. Among these, it is preferable to use a water-soluble cerium compound composed of a halogen compound, a nitrate, a sulfate, or an organic acid salt. Specific examples include cerium chloride, cerium nitrate, cerium acetate, cerium sulfate, and cerium carboxylate. Of these, cerium chloride and cerium nitrate are particularly preferable. These water-soluble cerium compounds can be used alone or in combination. The content of the water-soluble cerium compound contained in the transparency improving liquid of the second embodiment must be in the range of 2 to 80 wt%, and more preferably in the range of 2 to 40 wt%. If the content of the water-soluble cerium compound contained in the transparency improving liquid is less than 2 wt%, no improvement in transparency can be observed, even when the transparency improving liquid is applied to a prosthetic device. On the other hand, if the content exceeds 80 wt%, the solubility in water is significantly reduced, making it impossible to prepare a uniform transparency improving liquid.

[0095] The (a) water-soluble compound salt that is not an oxide contained in the transparency improving liquid of the second embodiment can be the same as that of the first embodiment and can be used in the same amount as that of the first embodiment. The (b) water in the second embodiment is necessary to dissolve or disperse the (a) water-soluble compound salt that is not an oxide and the (c) water-soluble cerium compound, and can be the same as that of the first embodiment. The content of water contained in the transparency improving liquid of the second embodiment is in the range of 8 to 86 wt%, preferably in the range of 30 to 70 wt%. If the content is low, the solubility of the (a) water-soluble compound salt that is not an oxide and the (c) water-soluble cerium compound will be poor, and if the blending amount is high, the transparency improving effect will be reduced.

[0096] In the transparency improving liquid of the second embodiment, the total content of (a) the water-soluble compound salt that is not an oxide and (c) the water-soluble cerium compound in the transparency improving liquid is preferably in the range of 30 to 70 wt%. If it is less than 30 wt%, the improvement in transparency is likely to be insufficient, while if it exceeds 70 wt%, the viscosity becomes high, and for example, when applying the transparency improving liquid to a prosthetic device, the penetration of the transparency improving liquid into the prosthetic device may be poor.

[0097] The transparency improving liquid may contain (d) 0.1 to 20 wt% of a water-soluble organic solvent. In this case, component (b) is water and / or vegetable oil. That is, in a third embodiment of the transparency improving liquid of the present invention, the transparency improving liquid contains (a) 10 to 80 wt% of a solution of a water-soluble compound salt that is not an oxide (excluding cerium compounds), (b) 8 to 86 wt% of water and / or vegetable oil, (c) 2 to 80 wt% of a water-soluble cerium compound, and (d) 0.1 to 20 wt% of a water-soluble organic solvent.

[0098] The water-soluble organic solvent (component (d)) contained in the transparency improving liquid of the third embodiment can be appropriately selected from those compatible with water and the vegetable oil described below. This water-soluble organic solvent preferably acts as a thickener to adjust the viscosity and does not leave behind any organic residue when sintering zirconia. Specific examples of this water-soluble organic solvent include alcohols, polyols, and glycol ethers, more specifically, methanol, ethanol, isopropanol, ethylene glycol, polyethylene glycol, acetone, 1,4-dioxane, and polypropylene glycol. Of these, polyethylene glycol and polypropylene glycol are preferred. The content of the water-soluble organic solvent contained in the transparency improving liquid of the third embodiment is in the range of 0.1 to 20 wt%. If the content is less than 0.1 wt%, an appropriate viscosity cannot be obtained, resulting in poor applicability when applying the transparency improving liquid to a prosthetic device. If the content exceeds 20 wt%, organic residue may remain when sintering zirconia.

[0099] The (a) water-soluble compound salt that is not an oxide contained in the transparency improving liquid of the third embodiment can be the same as that of the first embodiment and can be used in the same amount as that of the first embodiment. The (c) water-soluble cerium compound contained in the transparency improving liquid of the third embodiment can be the same as that of the second embodiment and can be used in the same amount as that of the second embodiment. Furthermore, the water used in component (b) of the third embodiment can be the same as that of the second embodiment and can be used in the same amount as that of the first embodiment. In the third embodiment, component (b) is composed of water and / or vegetable oil. The vegetable oil used in the transparency improving liquid of the third embodiment is not particularly limited, and any vegetable oil can be used. Specific examples include gammenene, pinene, D-limonene, and terpineol, with pinene and D-limonene being preferred. The vegetable oil content in the transparency improving liquid of the third embodiment is in the range of 8 to 86 wt%, preferably 30 to 70 wt%. A low content results in poor solubility of the (a) water-soluble compound salt that is not an oxide and the (c) component: the water-soluble cerium compound, while a high content results in a reduced transparency improvement effect.

[0100] In the transparency improving liquid of the third embodiment, the total content of (a) the water-soluble compound salt and (c) the water-soluble cerium compound in the transparency improving liquid is preferably in the range of 30 to 70 wt%. If it is less than 30 wt%, the improvement in transparency is likely to be insufficient, while if it exceeds 70 wt%, the viscosity becomes high, and for example, when applying the transparency improving liquid to a prosthetic device, the penetration of the transparency improving liquid into the prosthetic device may be poor.

[0101] The transparency improving liquid of the present invention may contain an organic marker based on an organic dye. In this way, when the transparency improving liquid is applied to a prosthetic device fabricated by cutting a dental zirconia workpiece, the area to which it is applied can be visualized, and the amount of applied transparency improving liquid and its penetration degree can also be visualized. The organic dye is required to be free of inorganic substances. Specific examples of organic dyes include gardenia yellow, annatto pigment, red cabbage pigment, etc., with red cabbage and gardenia yellow being preferred.

[0102] Next, a method for using the transparency improving liquid of the present invention will be described. The transparency improving liquid of the present invention is used, for example, by applying or immersing a zirconia object to be cut for dental cutting to support a water-soluble compound salt on the surface of the zirconia object to be cut for dental cutting. Specifically, the transparency improving liquid can be used as a water-soluble compound salt solution in which the zirconia object to be cut for dental cutting according to the first embodiment described above is immersed when producing the zirconia object to be cut for dental cutting. Furthermore, after producing the zirconia object to be cut for dental cutting according to the first and second embodiments described above, the transparency improving liquid can be used as a coating liquid to be applied to the produced zirconia object to be cut for dental cutting or to a dental prosthetic device made from the zirconia object to be cut for dental cutting.

[0103] In the method for using the transparency improving liquid of the present invention, the zirconia workpiece for dental cutting, which is to be coated with or immersed in the transparency improving liquid, preferably contains iron.

[0104] In order to provide a prosthetic device that has excellent translucency and excellent color saturation while maintaining high strength and that does not deform by applying the transparency improving liquid of the present invention to a zirconia workpiece for dental cutting and a prosthetic device machined from the zirconia workpiece for dental cutting, it is a preferred embodiment to apply the transparency improving liquid of the present invention to a prosthetic device machined from the following zirconia workpiece for dental cutting.

[0105] The transparency improving liquid of the present invention is applied to a pre-sintered zirconia object for dental cutting and the prosthetic device when a prosthetic device (semi-sintered body) is produced by cutting a porous pre-sintered zirconia object for dental cutting and the prosthetic device, and then the fully sintered body is improved in color saturation and transparency. That is, when applied to the pre-sintered zirconia object for dental cutting and the prosthetic device, the transparency improving liquid penetrates from the surface to the interior, improving the color saturation and transparency of the fully sintered prosthetic device that is then fully sintered. To achieve this, the relative density, specific surface area, composition, etc. of the zirconia object for dental cutting, which is used to produce the prosthetic device by cutting, affect these factors.

[0106] Therefore, when the transparency improving liquid of the present invention is applied to a zirconia object to be cut for dental cutting, which is used to prepare a prosthetic device by cutting, the relative density of the zirconia object to be cut for dental cutting is preferably 45 to 60%. In this specification, the relative density of the zirconia object to be cut for dental cutting refers to the apparent density of the zirconia object to be cut for dental cutting, which is a semi-sintered body, when the density of a fully sintered body is taken as 100%. If the relative density is less than 45%, the applied transparency improving liquid will penetrate too far into the interior, resulting in a decrease in the strength of the prosthetic device. On the other hand, if the relative density is more than 60%, there is a problem in that the applied transparency improving liquid will not penetrate easily. In addition, considering that the pre-sintered body is porous, the specific surface area of ​​the zirconia object to be cut for dental cutting is preferably 10 to 200 cm. 2 / g. The specific surface area is preferably in the range of 10 cm 2 If the specific surface area is less than 200 cm / g, the applied transparency improving liquid will not penetrate sufficiently. 2 If the viscosity exceeds 1 / g, the applied transparency improving liquid may penetrate too far into the interior, resulting in a decrease in the strength of the prosthetic device.

[0107] In addition, it is a preferred embodiment that the zirconia workpiece for dental cutting used to produce a prosthetic device to which the transparency improving liquid of the present invention is applied contains yttrium and / or erbium as a stabilizer, because this affects the color saturation and transparency of the prosthetic device to which the transparency improving liquid of the present invention is applied. The molar concentration of the stabilizer in the zirconia workpiece for dental cutting is preferably 4 mol% or less. If the molar concentration of the stabilizer in the zirconia workpiece for dental cutting exceeds 4 mol%, the transparency of the prosthetic device will be improved after complete sintering, but the strength may decrease.

[0108] There are no particular limitations on the type of prosthetic device to which the transparency improving liquid of the present invention is applied, and any prosthetic device, such as an inlay, laminate, crown, or bridge, can be used without any problems. Therefore, there are no particular limitations on the shape of the zirconia dental cutting object used to fabricate the prosthetic device by cutting, and any shape of zirconia dental cutting object can be used, such as a block shape corresponding to an inlay, laminate, or crown, or a disk shape corresponding to a bridge. Furthermore, in order to obtain a more aesthetic prosthetic device by applying the transparency improving liquid of the present invention, it is more preferable to use a multilayered block- or disk-shaped zirconia dental cutting object.

[0109] When the transparency improving liquid of the present invention is used as a coating liquid, it is preferable that the transparency improving liquid is produced by mixing all components, and it is preferably a liquid with fluidity. Note that there is no limitation on the state of the transparency improving liquid, and examples include a state in which all components are uniformly dissolved, a state in which they are separated into multiple layers, and a state in which a specific component is separated and precipitated, but there is no particular problem as long as the entire liquid is made uniform by shaking or other operations before use. Among these, from the viewpoint of the transparency improving liquid of the present invention penetrating into the prosthetic device after being applied, it is preferable that all components are dissolved and the liquid is in a fluid, low-viscosity state, as described above.

[0110] Furthermore, as for the method of applying the transparency improving liquid of the present invention to a prosthetic device, there is no problem as long as it is a method that can apply it uniformly to the surface of the prosthetic device, and there is no limitation to any application method, such as application with a brush, spraying with a spray or the like, or dropping with a pipette, etc. Among these, application with a brush or the like is preferred because it can be applied uniformly only to the surface of the prosthetic device.

[0111] When the transparency improving liquid of the present invention is used as a coating liquid, it is preferable to apply the transparency improving liquid only to the surface layer of the dental prosthesis machined from a zirconia workpiece for dental cutting. In this way, the transparency of only the surface layer can be improved in anticipation of the shape of a dental crown. For example, by applying the transparency improving liquid only to the enamel part of the dental crown, the cervical part can be maintained in an opaque state.

[0112] Next, a method for manufacturing a zirconia workpiece for dental cutting using the transparency improving liquid of the present invention will be described. When the transparency improving liquid of the present invention is used as a water-soluble compound salt solution in which a zirconia workpiece for dental cutting is immersed, for example, ceramic particles containing zirconium oxide and 2 to 7 mol% of an oxide stabilizer are prepared as a zirconia raw material powder. A colorant is then added to the ceramic particles, and the zirconia raw material powders with different colorant contents are press-molded in multiple stages to produce a press-molded body having a multilayer structure. The press-molded body is then subjected to CIP treatment and subsequently calcined (pre-sintered) at 800 to 1200°C to obtain a semi-sintered body. The semi-sintered body is then immersed in the transparency improving liquid of the present invention at a volume ratio of 10 to 100% based on the total volume of the semi-sintered body. The immersion time can be, for example, 1 to 120 hours under normal pressure, 0.5 to 12 hours under reduced pressure, or 0.2 to 6 hours under pressurized pressure.

[0113] When the transparency improving liquid of the present invention is used as a coating liquid for a zirconia object to be cut for dental cutting, a semi-sintered zirconia object to be cut for dental cutting is produced in the same manner as when the transparency improving liquid is used as a water-soluble compound salt solution in which the zirconia object to be cut for dental cutting is immersed. The transparency improving liquid of the present invention is applied to this semi-sintered zirconia object to be cut for dental cutting using a brush or the like. [Example]

[0114] The present invention will be described in more detail and specifically below with reference to examples, but the present invention is not limited to these examples.

[0115] [Preparation of zirconia cutting preforms for dental cutting] Preparation of zirconia pre-cutting body (A-1) for dental cutting Zirconia raw powder containing 3.0 mol% yttrium oxide (Zpex: manufactured by Tosoh Corporation, theoretical density: 6.092 g / cm 3 The mixture was filled into a mold (φ100 mm) and pressed (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then calcined in an electric furnace (1000°C, 30 minutes) to produce a zirconia pre-cut body (A-1) for dental cutting.

[0116] Preparation of zirconia pre-cutting body (A-2) for dental cutting Zirconia raw powder containing 3.0 mol% yttrium oxide (Zpex: manufactured by Tosoh Corporation, theoretical density: 6.092 g / cm 3 The mixture was packed into a mold (φ100 mm) and pressed (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then calcined in an electric furnace (800 °C, 30 minutes) to produce a zirconia pre-cut body (A-2) for dental cutting.

[0117] Preparation of zirconia pre-cutting body (A-3) for dental cutting Zirconia raw powder containing 3.0 mol% yttrium oxide (Zpex: manufactured by Tosoh Corporation, theoretical density: 6.092 g / cm 3 The mixture was filled into a mold (φ100 mm) and press-molded (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then pre-fired in an electric furnace (1200°C, 30 minutes) to produce a zirconia pre-cut body (A-3) for dental cutting.

[0118] Preparation of zirconia pre-cutting body (A-4) for dental cutting Zirconia raw powder containing 5.5 mol% yttrium oxide (Zpex SMILE: manufactured by Tosoh Corporation, theoretical density: 6.050 g / cm 3 The mixture was packed into a mold (φ100 mm) and pressed (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then calcined in an electric furnace (1000°C, 30 minutes) to produce a zirconia pre-cut body for dental cutting (A-4).

[0119] Preparation of zirconia pre-cutting body (A-5) for dental cutting Zirconia raw powder containing 6.5 mol% yttrium oxide (theoretical density: 6.035 g / cm 3 The mixture was filled into a mold (φ100 mm) and press-molded to obtain a green body. The green body (surface pressure: 30 MPa) was then subjected to CIP treatment (200 MPa, 1 minute). It was then pre-fired in an electric furnace (1000°C, 30 minutes) to produce a zirconia pre-cut body (A-5) for dental cutting.

[0120] Preparation of zirconia pre-cutting body (A-6) for dental cutting The zirconia pre-cutting material (A-6) for dental cutting was prepared from colored zirconia raw powder (theoretical density: 6.050 g / cm) containing 5.5 mol% yttrium. 3 The "Shofu Disk ZR Lucent FA" manufactured by laminating 100% SUS304 alloys was used.

[0121] Preparation of zirconia pre-cutting body (A-7) for dental cutting Zirconia raw powder containing 2.0 mol% yttrium oxide (theoretical density: 6.114 g / cm 3 The mixture was packed into a mold (φ100 mm) and pressed (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then calcined in an electric furnace (1000°C, 30 minutes) to produce a zirconia pre-cut body (A-7) for dental cutting.

[0122] Preparation of zirconia pre-cutting body (A-8) for dental cutting Zirconia raw powder containing 7.0 mol% yttrium oxide (theoretical density: 6.026 g / cm 3 The mixture was filled into a mold (φ100 mm) and pressed (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then calcined in an electric furnace (1000°C, 30 minutes) to produce a zirconia pre-cut body for dental cutting (A-8).

[0123] Preparation of zirconia pre-cutting body (A-9) for dental cutting Zirconia raw powder containing 3.0 mol% yttrium oxide (Zpex: manufactured by Tosoh Corporation, theoretical density: 6.092 g / cm 3 The mixture was packed into a mold (φ100 mm) and pressed (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then calcined in an electric furnace (700 °C, 30 minutes) to produce a zirconia pre-cut body for dental cutting (A-9).

[0124] Preparation of zirconia pre-cutting body (A-10) for dental cutting Zirconia raw powder containing 3.0 mol% yttrium oxide (Zpex: manufactured by Tosoh Corporation, theoretical density: 6.092 g / cm 3The mixture was filled into a mold (φ100 mm) and press-molded (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then pre-fired in an electric furnace (1300°C, 30 minutes) to produce a zirconia pre-cut body (A-10) for dental cutting.

[0125] Preparation of zirconia pre-cutting body (A-11) for dental cutting Zirconia raw powder (theoretical density: 6.050 g / cm) containing 3.0 mol% yttrium oxide and 3.3 mol% yttrium acetate 3 The mixture was packed into a mold (φ100 mm) and pressed (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then calcined in an electric furnace (1000°C, 30 minutes) to produce a zirconia pre-cut body (A-11) for dental cutting.

[0126] Preparation of zirconia pre-cutting body (A-12) for dental cutting Zirconia raw powder (theoretical density: 6.050 g / cm) containing 3.0 mol% yttrium oxide and 1.0 mol% yttrium acetate 3 The mixture was filled into a mold (φ100 mm) and pressed (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then pre-fired in an electric furnace (1000°C, 30 minutes) to produce a zirconia pre-cut body (A-12) for dental cutting.

[0127] Preparation of zirconia pre-cutting body (A-13) for dental cutting Zirconia raw powder containing 8.0 mol% yttrium oxide (theoretical density: 6.050 g / cm 3 The mixture was packed into a mold (φ100 mm) and pressed (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then calcined in an electric furnace (1300 °C, 30 minutes) to produce a zirconia pre-cut body for dental cutting (A-13).

[0128] Preparation of zirconia pre-cutting body (A-14) for dental cutting Zirconia raw powder containing 1.0 mol% yttrium oxide (theoretical density: 5.980 g / cm 3 The mixture was packed into a mold (φ100 mm) and pressed (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then calcined in an electric furnace (1300 °C, 30 minutes) to produce a zirconia pre-cut body for dental cutting (A-14).

[0129] Preparation of zirconia pre-cutting body (A-15) for dental cutting Zirconia raw powder (theoretical density: 6.050 g / cm) containing 6.3 mol% yttrium oxide and 0.1 mol% yttrium acetate 3 The mixture was packed into a mold (φ100 mm) and pressed (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then calcined in an electric furnace (1000°C, 30 minutes) to produce a zirconia pre-cut body (A-15) for dental cutting.

[0130] Preparation of zirconia pre-cutting body (A-16) for dental cutting Zirconia raw powder (theoretical density: 6.050 g / cm) containing 6.3 mol% yttrium oxide and 0.5 mol% yttrium acetate 3 The mixture was packed into a mold (φ100 mm) and pressed (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then calcined in an electric furnace (1000°C, 30 minutes) to produce a zirconia pre-cut body for dental cutting (A-16).

[0131] Preparation of zirconia pre-cutting body (A-17) for dental cutting Zirconia raw powder (theoretical density: 6.050 g / cm) containing 6.3 mol% yttrium oxide and 3.0 mol% yttrium acetate 3The mixture was packed into a mold (φ100 mm) and pressed (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then calcined in an electric furnace (1000°C, 30 minutes) to produce a zirconia pre-cut body (A-17) for dental cutting.

[0132] Preparation of zirconia pre-cutting body (A-18) for dental cutting Zirconia raw powder (theoretical density: 6.050 g / cm) containing 6.3 mol% yttrium oxide and 3.0 mol% calcium acetate 3 The mixture was packed into a mold (φ100 mm) and pressed (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then calcined in an electric furnace (1000°C, 30 minutes) to produce a zirconia pre-cut body (A-18) for dental cutting.

[0133] Preparation of zirconia pre-cutting body (A-19) for dental cutting Zirconia raw powder (theoretical density: 6.050 g / cm) containing 6.3 mol% yttrium oxide and 3.5 mol% yttrium acetate 3 The mixture was packed into a mold (φ100 mm) and pressed (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then pre-fired in an electric furnace (1000°C, 30 minutes) to produce a zirconia pre-cut body (A-19) for dental cutting.

[0134] Preparation of zirconia pre-cutting body (A-20) for dental cutting Zirconia raw powder (theoretical density: 6.050 g / cm) containing 6.3 mol% yttrium oxide and 4.0 mol% yttrium acetate 3 The mixture was packed into a mold (φ100 mm) and pressed (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then calcined in an electric furnace (1000°C, 30 minutes) to produce a zirconia pre-cut body (A-20) for dental cutting.

[0135] Preparation of zirconia pre-cutting body (A-21) for dental cutting Zirconia raw powder (theoretical density: 6.050 g / cm) containing 3.0 mol% yttrium oxide and 2.6 mol% yttrium acetate 3 The mixture was packed into a mold (φ100 mm) and pressed (surface pressure: 30 MPa) to obtain a green body. The green body was then subjected to CIP treatment (200 MPa, 1 minute). It was then pre-fired in an electric furnace (1000°C, 30 minutes) to produce a zirconia pre-cut body (A-21) for dental cutting.

[0136] [Relative density evaluation] Test specimens for evaluating relative density were prepared by cutting each zirconia pre-cut body for dental cutting into round plates (φ14 mm x 1.6 mm). The diameter, height, and weight of each test specimen were measured using a micro caliper, and their bulk density was also measured. The theoretical density of each test specimen was determined using the density of the fully sintered body obtained from each zirconia raw material powder. The relative density was calculated using the following formula: Relative density (%) = bulk density of each specimen (g / cm 3 ) / Theoretical density (g / cm 3 ) x 100

[0137] [Evaluation of specific surface area] The test specimens for specific surface area evaluation were prepared by cutting each dental cutting zirconia pre-cutting body into a cylindrical shape (φ4mm x 5mm). The BET specific surface area of ​​each test specimen was measured using an automatic specific surface area / pore distribution measuring device (Quantachrome).

[0138] Tables 1 to 3 show the compositions and properties of the zirconia preforms for dental cutting.

[0139] [Table 1]

[0140] [Table 2]

[0141] [Table 3] Relative density 55.4%, specific surface area 6.1m2 / g

[0142] [Preparation of Water-Soluble Compound Salt Solutions] The compositions of the water-soluble compound salt solutions are shown in Tables 4 and 5. The water-soluble compound salt solutions were prepared by adding various water-soluble compound salts to ion-exchanged water and stirring and mixing for 12 hours.

[0143] [Table 4]

[0144] [Table 5]

[0145] The zirconia pre-cutting bodies for dental cutting (A-1) to (A-14) were impregnated with a water-soluble compound salt solution by the following impregnation method to prepare the zirconia pre-cutting bodies for dental cutting. The zirconia pre-cutting bodies for dental cutting (A-15) to (A-21) were used as they were.

[0146] [Impregnation method] Impregnation method (C-1) Each zirconia pre-cut piece for dental cutting was immersed in each water-soluble compound salt solution for 1 hour under normal pressure, then removed from the water-soluble compound salt solution and dried under normal pressure (110°C, 12 hours).

[0147] Impregnation method (C-2) Each zirconia pre-cut piece for dental cutting was immersed in each water-soluble compound salt solution for 120 hours under normal pressure, after which it was removed from the water-soluble compound salt solution and dried under normal pressure (110°C, 12 hours).

[0148] Impregnation method (C-3) Each zirconia pre-cut piece for dental cutting was immersed in each water-soluble compound salt solution for 8 hours under normal pressure, then removed from the water-soluble compound salt solution and dried under normal pressure (110°C, 12 hours).

[0149] Impregnation method (C-4) Each zirconia pre-cut piece for dental cutting was immersed in each water-soluble compound salt solution for 8 hours under a reduced pressure (-720 mmHg). After that, the zirconia pre-cut piece for dental cutting was removed from the water-soluble compound salt solution and dried under normal pressure (110°C, 12 hours).

[0150] Impregnation method (C-5) Each zirconia pre-cut piece for dental cutting was immersed in each water-soluble compound salt solution for 8 hours under a pressurized atmosphere (0.5 MPa). After that, the zirconia pre-cut piece for dental cutting was removed from the water-soluble compound salt solution and dried under normal pressure (110°C, 12 hours).

[0151] Impregnation method (C-6) Each zirconia pre-cut piece for dental cutting was immersed in each water-soluble compound salt solution for 8 hours under normal pressure, then removed from the water-soluble compound salt solution and dried in a high-temperature environment (500°C, 12 hours).

[0152] Impregnation method (C-7) Each zirconia pre-cut piece for dental cutting was immersed in each water-soluble compound salt solution for 8 hours under normal pressure, then removed from the water-soluble compound salt solution and dried at high temperature (600°C for 12 hours).

[0153] Table 6 shows the manufacturing method in which the zirconia pre-cut body for dental cutting is immersed in a solution containing each stabilizer and then dried.

[0154] [Table 6]

[0155] [Evaluation of water-soluble compound salt content] Test specimens for evaluating the amount of water-soluble compound salt were prepared by cutting dental zirconia cutting bodies prepared by each impregnation method into round plates (φ14 mm x 1.6 mm). Each test specimen was quantitatively analyzed using a fluorescent X-ray analyzer (Rigaku Corporation). The amount of water-soluble compound salt was calculated in terms of oxide. The amount of water-soluble compound salt supported was calculated using the following formula. The molar fraction of semi-sintered ceramic particles was measured by cutting them into round plates (φ14 mm × 1.6 mm). Each specimen was quantitatively analyzed using an X-ray fluorescence spectrometer (Rigaku Corporation). The amount of stabilizer was calculated in terms of oxide, and the molar fractions of zirconium oxide and stabilizer were calculated. Furthermore, zirconia specimens for dental cutting, prepared by each manufacturing method, were cut into round plates (φ14 mm × 1.6 mm). Each specimen was quantitatively analyzed using an X-ray fluorescence spectrometer (Rigaku Corporation). The ratio of zirconium oxide and stabilizer in the semi-sintered ceramic particles was calculated from the molar fraction of zirconium oxide in the zirconia specimens for dental cutting. The molar amount of stabilizer was calculated, and this amount and the molar amount of stabilizer were then subtracted from the total amount of stabilizer and water-soluble compound obtained by X-ray fluorescence to determine the molar amount of water-soluble compound alone. A specific calculation example is shown below. Semi-sintered ceramic particles (molar fraction: zirconium oxide: 96.00 mol%, yttrium oxide: 3.00 mol%, others: 1.00 mol%) are impregnated with yttrium acetate, and the analytical results of the resulting zirconia cutting object for dental cutting are zirconium oxide: 94.00 mol%, yttrium oxide: 5.00 mol%, others: 1.00 mol%, Amount of water-soluble yttrium acetate supported = 5.00 - 3.00 × (94.00 ÷ 96.00) = 2.06 mol% In the above calculation example, the amount of yttrium oxide in the analysis results of the zirconia workpiece for dental cutting includes yttrium acetate converted into yttrium oxide.

[0156] [Translucency evaluation (contrast ratio evaluation)] Test specimens for evaluating translucency were prepared by cutting each zirconia workpiece for dental cutting into a round plate (φ14 mm × 1.6 mm). Each test specimen was fully fired in a firing furnace (1600°C, 2 hours). The thickness of each test specimen (1.0 mm) was then adjusted using a surface grinder. Translucency was evaluated by measuring the contrast ratio. The contrast ratio was measured using a spectrophotometer (Konica Minolta). The Y value when a white board was placed under each test specimen and color measurement was performed was defined as Yw, and the Y value when a black board was placed under the test specimen and color measurement was performed was defined as Yb. The contrast ratio was calculated using the following formula. Contrast ratio = Yb / Yw The closer the contrast ratio is to 0, the more transparent the material is; the closer the contrast ratio is to 1, the more opaque the material is.

[0157] [Bending strength evaluation] Bending test specimens were prepared by cutting each dental zirconia workpiece into plates (width: 4.8 mm x length: 20 mm x thickness: 1.6 mm). Each test specimen was fully sintered in a firing furnace (1600°C, 2 hours). The specimens were then adjusted to their size (width: 4.0 mm x length: 16 mm x thickness: 1.2 mm) using a surface grinder. Bending tests were performed in accordance with ISO 6872 (span distance: 12 mm, crosshead speed: 1.0 mm / min).

[0158] [Evaluation of uniformity of water-soluble compound salts] Test specimens for evaluating the uniformity of water-soluble compound salts were prepared by cutting each zirconia workpiece for dental cutting into round plates (φ14 mm × 1.6 mm). From each test specimen, a cylindrical section with a diameter of 1 mm was cut out from the center of the round plate, and a 0.12 mm ± 0.01 mm section and a 0.40 mm ± 0.01 mm section were cut out from the round plate surface. The amount of water-soluble compound salt contained in the cut-out sections was quantitatively analyzed using a fluorescent X-ray analyzer (manufactured by Rigaku Corporation), and the uniformity of the water-soluble compound salt was evaluated using the following formula: Uniformity (%) = (content of 0.40mm ± 0.01mm part) / (content of 0.12mm ± 0.01mm part)

[0159] Tables 7 to 12 show the results of property tests on the manufactured zirconia workpieces for dental cutting.

[0160] [Table 7]

[0161] [Table 8]

[0162] [Table 9]

[0163] [Table 10]

[0164] [Table 11]

[0165] [Table 12]

[0166] [Table 13]

[0167] [Table 14]

[0168] In Examples 1 to 33, in which the amount of stabilizer in the dental cutting zirconia pre-cut body (semi-sintered ceramic particle body) was 2 to 7 mol % and the amount of water-soluble compound salt in the dental cutting zirconia pre-cut body was 0.1 to 3.5 mol %, the contrast ratio was 0.76 or less and the bending strength was 500 or more, and it was confirmed that both bending strength and translucency could be achieved at high levels.

[0169] On the other hand, in Comparative Examples 1 to 4, in which the amount of stabilizer in the zirconia pre-cut body for dental cutting (semi-sintered ceramic particles) was not 2 to 7 mol%, or the amount of water-soluble compound salt in the zirconia pre-cut body for dental cutting was not 0.1 to 3.5 mol%, the contrast ratio was 0.78 or more, or the bending strength was less than 500, and high levels of bending strength and translucency were not achieved.

[0170] Next, examples of the transparency improving liquid of the present invention will be described.

[0171] [Preparation of transparency improving liquid] Tables 15 to 20 show the compositions of the transparency improving liquids for the Examples, Comparative Examples, and Reference Examples. The transparency improving liquids for the Examples, Comparative Examples, and Reference Examples were prepared by mixing (a) a water-soluble compound salt that is not an oxide (excluding cerium compounds), (b) water and / or vegetable oil, (c) a water-soluble cerium compound, and (d) a water-soluble organic solvent for 12 hours. The compositions in the tables are shown in wt% unless otherwise specified.

[0172] [Zirconia cutting specimen for dental cutting] Zirconia disks containing 3 mol% of stabilizer and 5 mol% of stabilizer were prepared as zirconia cutting objects for dental cutting. The zirconia disks were cut to the size required for the following tests and used. Table 18 shows the test results for the zirconia disks not treated with the transparency improving liquid of the present invention as Reference Examples 1 and 2.

[0173] [Preparation of transmittance test specimen] To measure transmittance, zirconia powder manufactured by Tosoh Corporation was molded into a dental cutting zirconia workpiece and pre-fired at 1100°C (with 3 mol% and 5 mol% stabilizer (yttrium)). From this dental cutting zirconia workpiece, a test piece with a diameter of 14 mm and a thickness of 1.6 mm was cut. This test piece was coated with 1 g of the transparency improving liquid described in each example for 10 minutes and thoroughly dried at 80°C for 1 hour. It was then sintered by holding it at a final temperature of 1450°C for 2 hours according to the method described in the instructions. The test piece was then adjusted to a thickness of 1.0 mm, and the visible light transmittance was measured.

[0174] [Preparation of bending test specimen] For the measurement of bending test specimens, a test specimen measuring 4.8 mm in width, 1.6 mm in thickness, and 20 mm in length was machined from the dental zirconia cutting specimen prepared for the transmittance test. 1 g of the transparency improving liquid described in each example was applied to this test specimen for 10 minutes and thoroughly dried at 80°C for 1 hour. Following the instructions, the specimen was sintered at a final temperature of 1450°C for 2 hours. The test specimen was then adjusted to a thickness of 1.2 mm and subjected to a three-point bending test. The test method conformed to ISO 6872.

[0175] [Color Measurement] To measure color, a specimen measuring 10 mm wide, 1.6 mm thick, and 10 mm long was machined from the zirconia dental cutting specimen prepared in the transmittance test. The specimen was then coated with the transparency-improving liquid described in the various examples for 10 minutes and thoroughly dried at 80°C for 1 hour. The specimen was then sintered at a final temperature of 1450°C for 2 hours according to the instructions. The specimen was then adjusted to a thickness of 1.0 mm, and the L*, a*, and b* values ​​were measured against a white background using a Konica Minolta colorimeter.

[0176] [Table 15]

[0177] [Table 16]

[0178] [Table 17]

[0179] [Table 18]

[0180] [Table 19]

[0181] [Table 20]

[0182] Examples 34 to 41 and 45 to 56 all exhibited a visible light transmittance of 30% or more and a bending strength of 900 MPa or more. Therefore, the visible light transmittance was improved without a significant decrease in strength compared to Reference Example 1 (no transparency improving liquid was used). Examples 42 to 44 also exhibited a visible light transmittance of 30% or more and a bending strength of 900 MPa or more. Therefore, the visible light transmittance was improved without a significant decrease in strength compared to Reference Example 2 (no transparency improving liquid was used). Comparative Example 5 did not contain component (a), and therefore showed almost no improvement in visible light transmittance compared to Reference Example 1. Comparative Examples 6, 8, and 9 had clinically sufficient transparency, but a significant decrease in bending strength. Comparative Examples 7 and 10 did not exhibit a decrease in strength, but did not exhibit sufficient transparency.

[0183] In this specification, even if a component of the invention is described as either singular or plural, or is described without being limited to either singular or plural, the component may be either singular or plural unless the context requires otherwise.

[0184] Although the present invention has been described with reference to detailed embodiments, it should be understood that those skilled in the art can make various changes or modifications based on the disclosure herein, and therefore, any changes or modifications are intended to be included within the scope of the embodiments of the present invention. [Industrial Applicability]

[0185] According to the present invention, it is possible to provide a fully sintered zirconia body that maintains high strength, has superior translucency and color saturation to those of a zirconia body for dental cutting produced from a zirconia raw material powder containing various stabilizers, and is free from deformation.

Claims

1. (a) a water-soluble compound salt solution that is not an oxide and contains at least one element selected from calcium, magnesium, and rare earth elements; (b) Water A method for using a clarity enhancing liquid comprising: A transparency improving liquid is applied to or immersed in a zirconia workpiece for dental cutting, and the water-soluble compound salt, which is not an oxide and contains at least one element selected from calcium, magnesium, and rare earth elements, is supported on the surface of a semi-sintered ceramic particle body; Zirconia for dental cutting workpieces with a specific surface area of ​​0.5 to 10 m ２ / g, The method for using a transparency improving liquid is characterized in that the ceramic particles contain zirconium oxide and a stabilizer made of an oxide in an amount of 2 to 7 mol % calculated as oxide.

2. A method for using the transparency improving liquid according to claim 1, A method for using a dental transparency improving liquid, wherein the water-soluble compound salt that is not an oxide and contains at least one element selected from calcium, magnesium, and rare earth elements contains an organic acid salt of yttrium.

3. A method for using the transparency improving liquid according to any one of claims 1 to 2, A method for using a transparency improving liquid, characterized in that the relative density of a zirconia workpiece for dental cutting is 50 to 70%.

4. A method for using the transparency improving liquid according to any one of claims 1 to 3, A method for using a transparency improving liquid, wherein a zirconia workpiece for dental cutting contains iron before being coated with or immersed in the transparency improving liquid.

5. A method for using the transparency improving liquid according to any one of claims 1 to 4, A method for using a transparency improving liquid, wherein a zirconia workpiece for dental cutting contains yttrium and / or erbium before being coated with or immersed in the transparency improving liquid.

6. A method for using the transparency improving liquid according to any one of claims 1 to 5, A method for using a transparency improving liquid, comprising applying the transparency improving liquid only to the surface layer of a dental prosthetic device machined from a zirconia workpiece for dental cutting.

7. A method for using the transparency improving liquid according to claim 6, comprising: A method of using a transparency enhancing liquid, wherein the dental prosthetic device is an inlay, laminate, crown or bridge.

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