Porcelain material for dentistry

Abstract

The present invention relates to a dental ceramic material, and more specifically, to a dental ceramic material comprising SiO2, CeO2, ZrO2, and an oxide of an alkaline earth metal, the content of SiO2 being 30.0-50.0% by mass per 100% by mass of the dental ceramic material, and the content of CeO2 being 10.0-50.0% by mass per 100% by mass of the dental ceramic material; and a method for producing a dental implant, said method comprising a step for applying the dental ceramic to a zirconia substrate, and a step for calcining the dental ceramic at 880-980 DEG C.

Description

Technical Field

[0001] The present invention relates to dental porcelain. Background Art

[0002] Dental opaque porcelain is mainly used to mask the metal color of the frame or to show the color of the bridge abutment through the frame.

[0003] For example, ceramics for metal bonding need to mask the metallic color of the base. Therefore, opaque ceramics have been used in products to produce aesthetically pleasing prostheses in which the metallic color is not visible on the crown surface.

[0004] Furthermore, in recent years, ceramics such as zirconia have become indispensable materials for the production of crowns requiring aesthetics, as they have a transparency and color tone similar to natural teeth.

[0005] On the other hand, in recent years, due to the popularity of high-strength and highly transparent ceramics, especially zirconia raw materials, the problem of insufficient shielding of the base metal color has been observed. As a result, opaque ceramics with high shielding properties are also required in ceramic sintering materials such as zirconia raw materials.

[0006] Furthermore, while conventional colored porcelain powders tend to offer greater hiding power than white porcelain, users who prefer bleaching tend to dislike colored prostheses. The high whiteness required for ceramic prostheses made of, for example, zirconia often fails to provide sufficient hiding power. For example, when using artificial roots or abutments, the metallic color of the base easily shows through the crown surface, leading to a demand for more aesthetically pleasing prostheses.

[0007] For example, Patent Document 1 discloses the following opaque dental porcelain material, characterized in that it contains 15 to 50 wt% of CeO2 as a dental metal masking material for masking the metallic color of a dental metal substrate during firing, and 40 to 50 wt% of aluminosilicate glass.

[0008] In addition, Patent Document 2 discloses the following porcelain composition set, which is a porcelain composition for making an all-ceramic crown restoration, and is composed of two layers constructed and calcined on an all-ceramic core. The porcelain composition set consists of a first layer of porcelain composition for a ceramic crown and a second layer of porcelain composition for a ceramic crown, and the first layer stacked on the all-ceramic core and calcined is a mixture containing 40.0-60.0 mass% of SiO2, 8.0-14.0 mass% of Al2O3, 0.5-4.0 mass% of B2O3, 3.0-6.0 mass% of Na2O, 5.0-9.0 mass% of K2O, 0.5-3.0 mass% of CaO, 0.1-2.0 mass% of MgO, and 0.2-0.0 mass% of ZrO2. The second layer is stacked on the first layer and calcined, and is composed of two or more glass powders formed by a glass composition containing 5.0 to 15.0 mass%. The second layer is stacked on the first layer and calcined, and is composed of two or more glass powders formed by a glass composition containing SiO2: 50.0 to 70.0 mass%, Al2O3: 12.0 to 21.0 mass%, B2O3: 2.0 to 9.0 mass%, Li2O: 0.05 to 0.2 mass%, Na2O: 4.0 to 12.0 mass%, K2O: 4.0 to 12.0 mass%, CaO: 0.5 to 5.0 mass%, and MgO: 0.1 to 2.0 mass%.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Application Laid-Open No. 10-94550

[0012] Patent Document 2: Japanese Patent Application Laid-Open No. 2007-126360 Summary of the Invention

[0013] Problems to be solved by the invention

[0014] However, the opaque dental porcelain disclosed in Patent Document 1 is a porcelain used for dental precious metal materials (Au, Au-Pd alloy, etc.) by sintering. When the porcelain is sintered to a ceramic base material, the porcelain may crack or break.

[0015] Furthermore, it is known that the porcelain composition disclosed in Patent Document 2 is a composition of porcelain for ceramic crowns, and that the porcelain can be baked and bonded to a ceramic base material, but has insufficient masking properties.

[0016] In addition, depending on the composition of the porcelain material, the porcelain material may be colored in colors such as black or yellow. In order to produce a prosthesis with good whiteness and higher aesthetics, it is necessary to suppress the coloring of the porcelain material while maintaining excellent hiding properties.

[0017] Therefore, an object of the present invention is to provide a dental ceramic material that can suppress the occurrence of cracks when sintered to a ceramic base material, has excellent shielding properties after firing, and can suppress coloration after firing.

[0018] Means used to solve problems

[0019] The present inventors have conducted intensive studies and, as a result, have found that the above-mentioned problems can be solved by using a dental ceramic material having a specific composition, thereby completing the present invention.

[0020] That is, the present invention includes the following technical solutions.

[0021] [1] Dental porcelain containing SiO2, CeO2, ZrO2 and oxides of alkaline earth metals,

[0022] The content of SiO2 is 30.0 to 50.0% by mass in 100% by mass of the dental porcelain material.

[0023] The content of CeO2 is 10.0 to 50.0% by mass in 100% by mass of the dental porcelain material.

[0024] [2] The dental porcelain material according to [1], wherein the content of the ZrO2 is 5.0 to 16.0 mass % in 100 mass % of the dental porcelain material.

[0025] [3] The dental porcelain material according to [1] or [2], further comprising Al2O3, K2O and Na2O,

[0026] The content of Al2O3 is 2.0 to 8.0 mass % in 100 mass % of the dental porcelain material.

[0027] The content of K2O is 1.0 to 7.0 mass % in 100 mass % of the dental porcelain material.

[0028] The content of Na2O is 4.0 to 10.0% by mass in 100% by mass of the dental porcelain material.

[0029] [4] The dental porcelain material according to any one of [1] to [3], wherein the alkaline earth metal oxides contain at least CaO and BaO,

[0030] The content of CaO is 0.2 to 2.0 mass % in 100 mass % of the dental porcelain material.

[0031] The content of BaO is 1.0 to 8.0 mass % in 100 mass % of the dental porcelain material.

[0032] [5] The dental porcelain material according to any one of [1] to [4], wherein the total content of the SiO2, CeO2, ZrO2 and the alkaline earth metal oxide is 70.0 to 95.0 mass % in 100 mass % of the dental porcelain material.

[0033] [6] The dental porcelain material according to any one of [1] to [5], wherein the CeO 2 is CeO 2 derived from an opacifying agent.

[0034] [7] The dental porcelain material according to any one of [1] to [6], wherein the thermal expansion coefficient of a calcined body obtained by calcining the dental porcelain material at a maximum calcination temperature of 930°C is 7.8×10 -6 / ℃ or above and less than 10.0×10 -6 / ℃.

[0035] [8] The dental porcelain according to any one of [1] to [7], wherein the transmittance of light of a wavelength of 555 nm is 10.0% or less in the thickness direction of a measurement sample having a thickness of 0.30 mm formed by calcining the dental porcelain at a maximum calcination temperature of 930°C.

[0036] [9] The dental porcelain material according to any one of [1] to [8], wherein a test piece having a thickness of 1.20 mm formed by firing the dental porcelain material at a maximum firing temperature of 930° C. is subjected to a calcination test using L * a * b * The lightness L obtained by color measurement in color space * Above 90.0.

[0037]

[10] A method for manufacturing a dental prosthesis, comprising: coating the dental porcelain described in any one of [1] to [9] on a zirconia substrate; and calcining the dental porcelain at 880 to 980°C.

[0038] Effects of the Invention

[0039] According to the present invention, it is possible to provide a dental porcelain material which can suppress the occurrence of cracks when being sintered to a ceramic base material, has excellent shielding properties after firing, and can suppress coloration after firing. DETAILED DESCRIPTION

[0040] Hereinafter, the present invention will be described in detail using embodiments.

[0041] In this specification, the upper limit and lower limit of the numerical range (for example, the content of each component, values calculated from each component, various physical properties, various production conditions, etc.) can be combined as appropriate.

[0042] That is, in this specification, the lower limit and upper limit values described in stages for numerical ranges can be independently combined. For example, based on the description of "preferably 10 to 90, more preferably 30 to 60" for the same item, "preferably the lower limit (10)" and "more preferably the upper limit (60)" can be combined to form "10 to 60."

[0043] In addition, with respect to the numerical range, for example, according to the description “preferably 10 to 90, more preferably 30 to 60”, the upper limit value may not be specifically specified, and only the lower limit value side may be specified as “above 10” or “above 30”. Similarly, the lower limit value may not be specifically specified, and only the upper limit value side may be specified as “below 90” or “below 60”.

[0044] In addition, unless otherwise specified, when a numerical range is abbreviated as "XX to YY", it means a range of XX or more and YY or less. For example, when it is written as "10 to 90", it means a range of 10 or more and 90 or less.

[0045] Similarly to the above, for example, based on the description of "preferably 10 or more, more preferably 30 or more" and "preferably 90 or less, more preferably 60 or less" for the same item, the "preferable lower limit (10)" and the "more preferably upper limit (60)" may be combined to form "10 or more and 60 or less." Also, similarly to the above, only the lower limit may be specified as "10 or more" or "30 or more," and similarly, only the upper limit may be specified as "90 or less" or "60 or less." This also applies to the case where the upper end of the aforementioned numerical range is "less than."

[0046] In addition, in this specification, the term "porcelain" refers to "dental porcelain" unless otherwise specified.

[0047] [Dental porcelain]

[0048] A dental porcelain material according to one embodiment of the present invention comprises SiO2, CeO2, ZrO2 and an oxide of an alkaline earth metal, wherein the content of the SiO2 is 30.0 to 50.0 mass % in 100 mass % of the dental porcelain material, and the content of the CeO2 is 10.0 to 50.0 mass % in 100 mass % of the dental porcelain material.

[0049] The dental porcelain material can exhibit the effects of the present invention by satisfying these conditions.

[0050] <Content of CeO₂>

[0051] By making the content of the aforementioned CeO₂ be 10.0% by mass or more in 100% by mass of the dental porcelain, the shielding property of the dental porcelain can be improved. In addition, by making the content of the aforementioned CeO₂ be 50.0% by mass or less in 100% by mass of the dental porcelain, the thermal expansion coefficient of the dental porcelain will not become too high, and the occurrence of cracks during sintering to the ceramic substrate can be suppressed.

[0052] From the same viewpoint, the content of the aforementioned CeO₂ is preferably 15.0 - 45.0% by mass, more preferably 18.0 - 40.0% by mass, and further preferably 19.0 - 31.0% by mass in 100% by mass of the dental porcelain.

[0053] <Content of SiO₂>

[0054] The dental porcelain as one embodiment of the present invention contains SiO₂, ZrO₂, and oxides of alkaline earth metals. In the composition satisfying the content of the aforementioned CeO₂, by making the content of the aforementioned SiO₂ be 30.0% by mass or more in 100% by mass of the dental porcelain, the excessive increase of the thermal expansion coefficient can also be suppressed, and the occurrence of cracks during sintering to the ceramic substrate can be suppressed. In addition, by making the content of the aforementioned SiO₂ be 50.0% by mass or less in 100% by mass of the dental porcelain, it can be sintered to the ceramic substrate even without calcining at a calcining temperature exceeding 1000°C, for example, and the calcining temperature can be adjusted within an appropriate range. Therefore, the coloring caused by the calcining of the porcelain can be suppressed.

[0055] Therefore, from the viewpoint of more easily exerting the effects of the present invention, the content of the aforementioned SiO₂ is preferably more than 30.0% by mass and 50.0% by mass or less, more preferably 33.0 - 48.0% by mass, and further preferably 37.0 - 45.0% by mass in 100% by mass of the dental porcelain.

[0056] <zro2>

[0057] From the viewpoint of more easily exhibiting the effects of the present invention, the content of ZrO2 is preferably 5.0 to 16.0 mass%, more preferably 6.0 to 15.0 mass%, and even more preferably 7.5 to 14.5 mass% in 100 mass% of the dental porcelain material.

[0058] <Alkaline earth metal oxides>

[0059] Examples of the alkaline earth metal oxide include one or more selected from the group consisting of MgO, CaO, SrO, and BaO.

[0060] From the viewpoint of more easily exhibiting the effects of the present invention, the dental porcelain material more preferably contains at least CaO or BaO as the alkaline earth metal oxide, and more preferably contains at least CaO and BaO.

[0061] In addition, from the viewpoint of more easily exerting the effects of the present invention, it is further preferred that: in the aforementioned dental porcelain, as the aforementioned alkaline earth metal oxides, at least CaO and BaO are contained, the content of the aforementioned CaO is 0.2 to 2.0 mass% in 100 mass% of the dental porcelain, and the content of the aforementioned BaO is 1.0 to 8.0 mass% in 100 mass% of the dental porcelain.

[0062] From the viewpoint of more easily exhibiting the effects of the present invention, the CaO content is more preferably 0.3 to 1.5 mass %, and even more preferably 0.4 to 1.0 mass %, based on 100 mass % of the dental porcelain material.

[0063] From the viewpoint of more easily exhibiting the effects of the present invention, the BaO content is more preferably 2.0 to 7.5 mass %, and even more preferably 3.0 to 6.0 mass %, based on 100 mass % of the dental porcelain material.

[0064] In addition, from the viewpoint of more easily exerting the effects of the present invention, in the dental porcelain, the total content of the alkaline earth metal oxides is preferably 1.2 to 10.0 mass %, more preferably 2.3 to 9.0 mass %, and even more preferably 3.4 to 7.0 mass % in 100 mass % of the dental porcelain.

[0065] In addition, from the perspective of more easily bringing out the effects of the present invention, in the aforementioned dental porcelain material, the total content of the aforementioned SiO2, the aforementioned CeO2, the aforementioned ZrO2, and the oxide of the aforementioned alkaline earth metal is preferably 45.0 to 100% by mass, more preferably 50.0 to 99.0% by mass, further preferably 55.0 to 98.0% by mass, still further preferably 65.0 to 97.5% by mass, still further preferably 70.0 to 95.0% by mass, still further preferably 75.0 to 90.0% by mass, and still further preferably 78.0 to 86.0% by mass in 100% by mass of the dental porcelain material.

[0066] <Al2O3, K2O, and Na2O>

[0067] From the perspective of more easily bringing out the effects of the present invention, the aforementioned dental porcelain material preferably further contains at least one or more selected from Al2O3, K2O, and Na2O, and more preferably contains Al2O3, K2O, and Na2O.

[0068] In addition, from the perspective of more easily bringing out the effects of the present invention, the aforementioned dental porcelain material is further preferably further contains Al2O3, K2O, and Na2O. The content of the aforementioned Al2O3 is 2.0 to 8.0% by mass in 100% by mass of the dental porcelain material, the content of the aforementioned K2O is 1.0 to 7.0% by mass in 100% by mass of the dental porcelain material, and the content of the aforementioned Na2O is 4.0 to 10.0% by mass in 100% by mass of the dental porcelain material.

[0069] From the perspective of more easily bringing out the effects of the present invention, the content of the aforementioned Al2O3 is more preferably 3.0 to 7.0% by mass, and further preferably 3.5 to 6.5% by mass in 100% by mass of the dental porcelain material.

[0070] From the perspective of more easily bringing out the effects of the present invention, the content of the aforementioned K2O is more preferably 2.0 to 6.5% by mass, and further preferably 3.0% or more and less than 5.5% by mass in 100% by mass of the dental porcelain material.

[0071] From the perspective of more easily bringing out the effects of the present invention, the content of the aforementioned Na2O is more preferably 5.0 to 9.0% by mass, and further preferably 6.0 to 8.5% by mass in 100% by mass of the dental porcelain material.

[0072] In addition, when the dental porcelain further contains at least one selected from Al2O3, KO, and Na2O, from the viewpoint of more easily exerting the effects of the present invention, in the dental porcelain, the total content of the SiO2, CeO2, ZrO2, the alkaline earth metal oxide, and at least one selected from Al2O3, KO, and Na2O is preferably 50.0 to 100 mass%, more preferably 55.0 to 100 mass%, even more preferably 65.0 to 98.0 mass%, even more preferably 70.0 to 100 mass%, even more preferably 75.0 to 100 mass%, even more preferably 80.0 to 100 mass%, even more preferably 83.5 to 100 mass%, even more preferably 90.0 to 100 mass%, even more preferably 95.0 to 100 mass%, and even more preferably 98.0 to 100 mass%, based on 100 mass% of the dental porcelain.

[0073] In one embodiment of the present invention, the CeO 2 contained in the dental porcelain is preferably blended as an opacifying agent. In other words, the CeO 2 is preferably CeO 2 derived from an opacifying agent.

[0074] In addition, in one embodiment of the present invention, as described above, when the CeO2 contained in the dental porcelain is compounded in the form of an opacifying agent, the compounding amount of the CeO2 compounded in the form of the opacifying agent is the same except that the expression "content" in the description related to the CeO2 content is changed to "compounding amount" and the expression "in 100 mass % of the dental porcelain" is changed to "in 100 mass % of the raw material components of the dental porcelain", and the suitable amount is also the same.

[0075] In one embodiment of the present invention, the SiO 2 contained in the dental porcelain is preferably blended as a glass component. That is, the SiO 2 is preferably SiO 2 derived from a glass component.

[0076] In addition, in one embodiment of the present invention, as described above, when the SiO2 contained in the dental porcelain is compounded in the form of a glass component, the compounding amount of the SiO2 compounded in the form of the glass component is the same except that the expression "content" in the description related to the content of the SiO2 is changed to "compounding amount" and the expression "in 100% by mass of the dental porcelain" is changed to "in 100% by mass of the raw material components of the dental porcelain", and the suitable amount is also the same.

[0077] In one embodiment of the present invention, the ZrO2 contained in the dental porcelain is preferably blended as a glass component. In other words, the ZrO2 is preferably ZrO2 derived from a glass component.

[0078] In addition, in one embodiment of the present invention, as described above, when the ZrO2 contained in the dental porcelain is compounded in the form of a glass component, the suitable compounding amount of the ZrO2 compounded in the form of the glass component is the same except that the expression "content" in the description related to the content of the ZrO2 is changed to "compounding amount" and the expression "in 100 mass % of the dental porcelain" is changed to "in 100 mass % of the raw material components of the dental porcelain".

[0079] In one embodiment of the present invention, the alkaline earth metal oxide contained in the dental porcelain is preferably blended as a glass component. In other words, the alkaline earth metal oxide is preferably an alkaline earth metal oxide derived from the glass component.

[0080] In one embodiment of the present invention, when the alkaline earth metal oxide contained in the dental porcelain is compounded in the form of a glass component as described above, the suitable total compounding amount of the alkaline earth metal oxide compounded in the form of the glass component is the same except that the expression "total content" in the description related to the total content of the alkaline earth metal oxide is changed to "total compounding amount" and the expression "in 100% by mass of the dental porcelain" is changed to "in 100% by mass of the raw material components of the dental porcelain".

[0081] In one embodiment of the present invention, when the CaO is compounded as a glass component as a suitable embodiment of the alkaline earth metal oxide, the suitable compounding amount of the CaO compounded as the glass component is the same except that the expression "content" in the description related to the CaO content is changed to "compounding amount" and the expression "in 100 mass % of the dental porcelain material" is changed to "in 100 mass % of the raw material components of the dental porcelain material".

[0082] Similarly, in one embodiment of the present invention, as a suitable embodiment of the aforementioned alkaline earth metal oxide, when the aforementioned BaO is compounded in the form of a glass component, the suitable compounding amount of BaO compounded in the form of the aforementioned glass component is the same except that the expression "content" in the description related to the aforementioned BaO content is changed to "compounding amount" and the expression "in 100 mass % of the dental porcelain material" is changed to "in 100 mass % of the raw material components of the dental porcelain material".

[0083] In one embodiment of the present invention, when the CeO2 contained in the dental porcelain is compounded as an opacifying agent, and the SiO2, the ZrO2, and the alkaline earth metal oxide are compounded as a glass component, the total compounding amount of the CeO2 compounded as the opacifying agent and the SiO2, ZrO2, and the alkaline earth metal oxide compounded as the glass component is the same except that the expression "total content" in the description related to the total content of the SiO2, the CeO2, the ZrO2, and the alkaline earth metal oxide is changed to "total compounding amount", and the expression "in 100% by mass of the dental porcelain" is changed to "in 100% by mass of the raw material components of the dental porcelain".

[0084] In one embodiment of the present invention, when the dental porcelain further comprises at least one oxide selected from Al2O3, KO, and Na2O, the at least one oxide selected from Al2O3, KO, and Na2O is preferably blended as a glass component. In other words, the at least one oxide selected from Al2O3, KO, and Na2O is preferably derived from the glass component.

[0085] In addition, in one embodiment of the present invention, as described above, when the Al2O3 optionally contained in the dental porcelain is compounded in the form of a glass component, the suitable compounding amount of the Al2O3 compounded in the form of the glass component is the same except that the expression "content" in the description related to the Al2O3 content is changed to "compounding amount" and the expression "in 100 mass % of the dental porcelain" is changed to "in 100 mass % of the raw material components of the dental porcelain".

[0086] Similarly, in one embodiment of the present invention, as described above, when the K2O optionally contained in the dental porcelain is compounded as a glass component, the suitable compounding amount of the K2O compounded as the glass component is the same except that the expression "content" in the description related to the K2O content is changed to "compounding amount" and the expression "in 100% by mass of the dental porcelain" is changed to "in 100% by mass of the raw material components of the dental porcelain".

[0087] Similarly, in one embodiment of the present invention, as described above, when the Na2O optionally contained in the dental porcelain is compounded as a glass component, the suitable compounding amount of the Na2O compounded as the glass component is the same except that the expression "content" in the description related to the content of the Na2O is changed to "compounding amount" and the expression "in 100% by mass of the dental porcelain" is changed to "in 100% by mass of the raw material components of the dental porcelain".

[0088] In one embodiment of the present invention, the CeO2 contained in the dental porcelain is mixed as an opacifying agent, the SiO2, the ZrO2 and the alkaline earth metal oxide are mixed as a glass component, and further, when at least one selected from the Al2O3, the K2O and the Na2O is mixed as a glass component, the CeO2 mixed as the opacifying agent, the SiO2, the ZrO2 and the alkaline earth metal oxide are mixed as the glass component, and the total amount of at least one selected from Al2O3, K2O and Na2O compounded in the form of the aforementioned glass component are the same except that the expression "total content" in the records related to the total content of the aforementioned SiO2, the aforementioned CeO2, the aforementioned ZrO2 and the aforementioned alkaline earth metal oxide, and at least one selected from Al2O3, K2O and Na2O is changed to "total compounding amount", and the expression "in 100% by mass of the dental porcelain material" is changed to "in 100% by mass of the raw material components of the dental porcelain material".

[0089] In addition, in one embodiment of the present invention, the aforementioned glass is preferably a glass containing the aforementioned SiO2, the aforementioned ZrO2 and the aforementioned alkaline earth metal oxide, and more preferably a glass containing the aforementioned SiO2, the aforementioned ZrO2 and the aforementioned alkaline earth metal oxide, and at least one selected from the aforementioned Al2O3, K2O and Na2O.

[0090] Furthermore, as suitable embodiments of these glasses, aluminosilicate glass containing each of the aforementioned components is further preferred.

[0091] In this specification, unless otherwise specified, the aforementioned "glass component" refers to one component constituting "glass".

[0092] Furthermore, the aforementioned oxides shown as the aforementioned "glass components" contained in the aforementioned "glass" express the composition of the metal components contained in the "glass" in terms of metal oxides. However, the "glass" does not necessarily contain the respective glass components in the form of the aforementioned oxides. In the field of ceramic materials such as glass and ceramics, it is common technical knowledge in the art to express the composition of the ceramic composition obtained by firing and the metal components contained in the composition in terms of metal oxides, as described above.

[0093] <Other ingredients>

[0094] The dental porcelain material may further contain, as components other than the aforementioned components, components derived from other glass components, pigments, fluorescent agents, opacifying agents, and the like.

[0095] The aforementioned component derived from other glass components is not particularly limited as long as it exhibits the effects of the present invention, and may be, for example, at least one selected from Li₂O, Sb₂O₃, B₂O₃, ZnO, SnO₂, Fe₂O₃, P₂O₅, Cl, and F. It should be noted that the content of oxides exhibiting multiple valences among these components can be calculated by converting the content to the valences of the components listed above. For example, FeO can be calculated by converting it to ½Fe₂O₃.

[0096] As a pigment or fluorescent agent, an oxide of at least one element selected from the group consisting of P, V, Cr, Mn, Fe, Co, Ni, Zn, Y, Sn, Sb, Bi, Pr, Sm, Eu, Gd, Tb and Er can be used.

[0097] As the opacifying agent, for example, at least one crystalline compound selected from the group consisting of ZrSiO 4 and SnO 2 can be used. The pigment, fluorescent agent, and shielding material may be a single compound or a plurality of compounds.

[0098] In one embodiment of the present invention, the contents of the aforementioned oxides in dental porcelain are determined by combining known analytical methods such as fluorescent X-ray analysis, atomic absorption spectrometry, and inductively coupled plasma (ICP) emission spectrometry with a variety of analytical instruments capable of component-by-component quantification, adding up the respective quantitative values and converting them so that the total becomes 100%. This allows confirmation of the composition of the dental porcelain and the composition of the glass that can serve as a raw material for the dental porcelain.

[0099] For example, the contents of SiO2, CeO2, ZrO2, CaO, BaO, Al2O3, K2O, and Na2O can be measured by, for example, fluorescent X-ray analysis. Furthermore, the content of Li2O, which cannot be detected by fluorescent X-ray analysis, can be measured by, for example, atomic absorption spectrometry. Similarly, the content of B2O3, which cannot be quantified by fluorescent X-ray analysis, can be measured by, for example, ICP emission spectrometry.

[0100] In addition, for example, in one embodiment of the present invention, the composition calculated based on the mixing ratio of each component constituting the aforementioned dental porcelain material (when a glass component is used, it is the composition of the glass containing the glass component or the mixing ratio of its raw materials) can also be regarded as the composition of the dental porcelain material.

[0101] Here, in this specification, the aforementioned oxides contained in the dental porcelain are expressed in terms of metal oxides to represent the composition of the metal components contained in the dental porcelain. Dental porcelain does not necessarily need to contain the respective components in the form of the aforementioned oxides. As described above, the same applies to the glass that can serve as the raw material for the dental porcelain. In the field of porcelain materials such as glass and ceramics, it is common knowledge in the art to express the composition of the porcelain composition obtained by calcination and the metal components contained in the composition in terms of metal oxides, as described above.

[0102] <Method for Manufacturing Dental Porcelain>

[0103] Next, a preferred embodiment of the method for producing the dental porcelain will be described. Here, an example in which CeO2 is mixed as an opacifying agent and the other oxide components are mixed as glass components will be described.

[0104] (Production of glass raw materials)

[0105] First, the raw glass for the porcelain material is prepared. For example, raw materials (oxides, carbonates, etc.) with a composition corresponding to the oxides of the raw glass are prepared and mixed. The mixed raw materials are then melted in a crucible, preferably at 1300-1600°C for 2-8 hours. The melt is then quenched in water to produce cullet. This cullet is then crushed using a roller mill or ball mill and sieved to a specified particle size range.

[0106] (Production of dental porcelain)

[0107] Next, the prepared primary glass powder (glass powder containing glass components) is mixed with CeO2 used as an opacifying agent. At this time, inorganic pigments, fluorescent agents, etc. are sometimes added and mixed at the same time to optimize the calcination temperature, color tone, and fluorescence of the porcelain material.

[0108] The mixing conditions are not particularly limited, and the components can be added together or in portions. A conventional kneader can be used for mixing. Examples include a mortar, a twin-shaft kneader (TWINMIX), a triple-shaft kneader (TRIMIX), a kneader, and a planetary mixer.

[0109] The mixed powder is preferably heat-treated at 750-880°C for 0.5-2.5 hours. The heat treatment temperature is more preferably 770-850°C, even more preferably 780-845°C, and even more preferably 790-840°C. A heat treatment temperature of 880°C or lower eliminates the need for melting more CeO₂ into the glass, allowing CeO₂'s opacifying effect to be more effectively exerted. This is preferable from the perspective of preventing, for example, discoloration of the dental porcelain. Furthermore, a heat treatment temperature of 750°C or higher facilitates CeO₂ fusion with the glass, making it difficult for the CeO₂ fine powder to separate from the glass. This is preferable from the perspective of preventing problems such as poor workability when the dental porcelain is used with solvent. The heat treatment time is more preferably 0.5-2 hours, even more preferably 1-2 hours.

[0110] Next, the calcined product of the glass and CeO2 fusion is coarsely crushed, and the coarse crushed product is further pulverized in a pot mill until it reaches a predetermined particle size range. Thereafter, the coarse particles are removed from the pulverized product by sieving to obtain a ceramic powder.

[0111] In one embodiment of the present invention, the average particle size of the ceramic powder is not particularly limited as long as the effects of the present invention are exhibited, but is preferably 1 to 30 μm, more preferably 2 to 25 μm, and even more preferably 3 to 20 μm.

[0112] The average particle size of the ceramic powder is a volume-based average particle size (D50) that can be determined by measurement using a laser diffraction scattering method, and can be measured, for example, by the method described in Examples.

[0113] In addition, as shown in one suitable embodiment of the method for producing dental porcelain, one embodiment of the present invention includes a dental porcelain obtained by mixing glass as a glass component containing at least SiO2, ZrO2, and an oxide of an alkaline earth metal with CeO2 as an opacifying agent. More preferably, a dental porcelain obtained by mixing glass as a glass component containing at least SiO2, ZrO2, and an oxide of an alkaline earth metal with CeO2 as an opacifying agent and heat-treating the mixture. The mixing amounts and suitable amounts of the components when mixing are independently the same as the mixing amounts of the components described in the section on dental porcelain.

[0114] The SiO₂, ZrO₂, alkaline earth metal oxide, and CeO₂ in the dental porcelain material of this embodiment are the same as those described in the dental porcelain material of one embodiment of the present invention, and their suitable methods are also the same. Furthermore, the content of each component in the resulting dental porcelain material and their suitable methods are also the same. Furthermore, the aforementioned mixing conditions, as well as the aforementioned heat treatment conditions and their suitable methods after mixing, are also the same as those described in the aforementioned embodiment of the method for manufacturing dental porcelain material.

[0115] <Thermal Expansion Coefficient of Dental Ceramics>

[0116] In one embodiment of the present invention, from the viewpoint of more easily suppressing the occurrence of cracks when the dental porcelain is sintered to a ceramic substrate, the thermal expansion coefficient at 30 to 450°C, measured at a heating rate of 10°C / min in accordance with ISO 6872 (2015), is preferably 7.8×10 -6 / ℃ or above and less than 10.0×10 -6 / °C, more preferably 7.8×10 -6 / ℃ and above 9.8×10 -6 / °C or less, more preferably 7.9×10 -6 / ℃ and above 9.7×10 -6 / ℃ below.

[0117] Specifically, the value of the thermal expansion coefficient is a value calculated by the method described in the Examples.

[0118] <Transmittance of Dental Ceramics>

[0119] In one embodiment of the present invention, from the perspective of easily improving the shielding properties of the dental porcelain, the transmittance of light at a wavelength of 555 nm relative to the thickness direction of a 0.30 mm thick measurement sample formed from a calcined body obtained by calcining the dental porcelain at a maximum calcination temperature of 930°C is preferably 10.0% or less, more preferably 8.0% or less, even more preferably 5.0% or less, even more preferably 3.0% or less, even more preferably less than 1.0%, and even more preferably 0.9% or less. The lower limit of the transmittance is not particularly limited and is 0%, for example, 0.1%. As described above, these step-by-step lower and upper limits can be independently combined. For example, in one embodiment of the present invention, the transmittance of the dental porcelain is preferably 0 to 10.0%, more preferably 0 to 8.0%, further preferably 0 to 5.0%, even more preferably 0 to 3.0%, even more preferably 0% or more and less than 1.0%, even more preferably 0 to 0.9%. For example, it can be 0.1 to 10.0%, 0.1 to 8.0%, 0.1 to 5.0%, 0.1 to 3.0%, 0.1% or more and less than 1.0%, or 0.1 to 0.9%.

[0120] Specifically, the transmittance value is a value calculated by the method described in Examples.

[0121] <Lightness of Dental Porcelain>

[0122] In one embodiment of the present invention, from the viewpoint of making the aesthetics of the dental ceramic material more excellent, a test piece having a thickness of 1.20 mm formed by firing the dental ceramic material at a maximum firing temperature of 930° C. was subjected to a calcination test. * a * b * The lightness L obtained by color measurement in color space * It is preferably 90.0 or higher, more preferably 91.0 or higher, and even more preferably 92.0 or higher.

[0123] In addition, the aforementioned lightness L * The upper limit of is not particularly limited, and may be, for example, 99.0, 98.0, or 97.0.

[0124] As described above, the lower limit and upper limit values described in these stages can be independently combined. For example, in one embodiment of the present invention, the lightness L of the dental porcelain material is * It may be 90.0-99.0, 90.0-98.0, 90.0-97.0, 91.0-99.0, 91.0-98.0, 91.0-97.0, 92.0-99.0, 92.0-98.0, or 92.0-97.0.

[0125] Specifically, the aforementioned lightness L * The values are values calculated by the methods described in Examples.

[0126] <Chroma of Dental Porcelain>

[0127] In one embodiment of the present invention, from the viewpoint of making the aesthetics of the dental ceramic material more excellent, a test piece having a thickness of 1.20 mm formed by firing the dental ceramic material at a maximum firing temperature of 930° C. was subjected to a calcination test. * a * b * The chromaticity a obtained by color measurement in color space * It is preferably -2.4 to +1.2, more preferably -2.3 to +1.1, and still more preferably -2.2 to +1.0.

[0128] In one embodiment of the present invention, from the viewpoint of making the aesthetics of the dental ceramic material more excellent, a test piece having a thickness of 1.20 mm formed by firing the dental ceramic material at a maximum firing temperature of 930° C. was subjected to a calcination test. * a * b * The chromaticity b obtained by color measurement in color space * It is preferably -5.6 to +7.4, more preferably -5.5 to +7.3, and still more preferably -5.4 to +7.2.

[0129] Specifically, the chromaticity a * and b * The values are values calculated by the methods described in Examples.

[0130] [Method for manufacturing dental porcelain prosthesis]

[0131] In addition, as a suitable embodiment, the following method for producing a dental prosthesis can be cited, which includes: a step of applying the dental porcelain material, which is one embodiment of the present invention, to a zirconia substrate; and a step of calcining the dental porcelain material at 880 to 980°C. The calcining temperature of the dental porcelain material is preferably 880 to 980°C, more preferably 900 to 960°C, and even more preferably 920 to 940°C. This is preferred because, for example, when the porcelain material is sintered on a ceramic substrate such as a zirconia crown, damage to the ceramic substrate such as the zirconia crown can be suppressed. Furthermore, deformation of the ceramic substrate due to overheating can be suppressed, which is also preferred.

[0132] [Applications of dental porcelain materials, etc.]

[0133] The dental ceramic material as one embodiment of the present invention can be suitably used as a dental ceramic material for use in a ceramic base material, and can be used to produce dental prostheses such as ceramic inlays, onlays, laminated veneers, and crowns.

[0134] The frame to be filled with the dental porcelain paste as one embodiment of the present invention is not particularly limited, but a ceramic frame is a suitable example, and a zirconia frame is a preferred example of the ceramic frame.

[0135] The use of the dental porcelain is not particularly limited, and it can be used as, for example, body porcelain (dentine-colored porcelain), neck porcelain, incisal porcelain (enamel-colored porcelain), translucent porcelain, opaque porcelain, colored porcelain, etc.

[0136] In addition, another embodiment of the present invention includes the use of the dental ceramic material in tooth treatment (eg, aesthetic dentistry, treatment of defective teeth, prosthetic restorations such as artificial teeth, treatment of caries, etc.).

[0137] In any of the aforementioned embodiments, the types and contents of the various components may be appropriately modified according to the aforementioned description, and any component may be added, deleted, or otherwise modified. Furthermore, in any of the aforementioned embodiments, the composition and property values of the various dental ceramic materials may be appropriately modified and combined. Therefore, the aforementioned dental ceramic materials may be used singly or in appropriate combinations of two or more, as long as the effects of the present invention are achieved.

[0138] The present invention includes various combinations of the above-described configurations within the scope of the technical concept of the present invention as long as the effects of the present invention are exhibited.

[0139] Example

[0140] Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples at all.

[0141] [Examples 1 to 7 and Comparative Examples 1 to 4]

[0142] Dental porcelain materials of Examples and Comparative Examples were produced as follows, and their properties were evaluated.

[0143] <Production of Raw Glass>

[0144] To prepare the primary glass powder, the raw materials (silicon dioxide, aluminum oxide, potassium carbonate, sodium carbonate, sodium nitrate, calcium carbonate, barium carbonate, barium fluoride, zirconium oxide, antimony trioxide, yttrium oxide, basic magnesium carbonate, lithium carbonate, boric acid, etc.) were mixed to obtain the composition shown in Table 1 below. The mixed raw materials were melted in a crucible at 1450°C for 4 hours. The melt was quenched in water to produce cullet, which was then pulverized in a ball mill and sieved through a #100 mesh stainless steel sieve to obtain the primary glass powder.

[0145] It should be noted that in Table 1, other components described as "others" include Sb2O3, Y2O3, HfO2, LiO2, B2O3, F, etc.

[0146] [Table 1]

[0147] Table 1

[0148] Glass 1 Glass 2 Glass 3 Glass 4 Glass 5 Glass 6 Glass 7 Glass 8 Glass 9 <![CDATA[SiO2]]> 54.3 54.8 56.0 53.7 56.9 55.1 62.6 62.0 61.6 <![CDATA[Al2O3]]> 6.8 7.1 6.4 6.7 7.0 18.8 10.4 5.3 15.3 <![CDATA[K2O]]> 5.8 6.1 5.5 5.7 6.0 11.0 7.8 6.0 12.8 <![CDATA[Na2O]]> 9.5 10.3 9.2 9.6 10.1 12.0 14.2 6.6 7.5 CaO 0.9 1.0 0.9 0.9 1.0 0.5 0.5 0.1 0.8 BaO 5.9 6.4 5.8 6.0 6.3 - - 1.4 - <![CDATA[ZrO2]]> 16.5 12.0 16.1 14.6 12.4 - 1.2 13.7 - other 0.3 2.3 0.1 2.8 0.3 2.6 3.3 4.9 2.0 total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

[0149] (In the table, the content of each component is expressed in mass %.)

[0150] <Production of Porcelain Powder>

[0151] The primary glass powders shown in Table 1 and CeO2 as an opacifying agent were mixed at the ratios shown in Table 2. Note that TiO2 was also mixed as an opacifying agent in Comparative Example 3. The mixed powders were heat treated at 840°C for 2 hours.

[0152] Next, the calcined product of the fusion of glass and CeO₂ (in Comparative Example 3, glass, CeO₂, and TiO₂) was coarsely crushed using a jaw crusher. The resulting coarse crushed product was further pulverized using a ball mill until the average particle size reached 15 μm. The crushed product was then sieved using a #100 mesh stainless steel sieve to remove coarse particles, thereby obtaining a ceramic powder.

[0153] The compositions of the obtained ceramic powders are shown in Table 3 below.

[0154] The average particle size is a volume-based average particle size (D50), which can be determined by a laser diffraction scattering method. Specifically, the laser diffraction scattering method can be performed, for example, using a laser diffraction particle size distribution analyzer (SALD-2300: manufactured by Shimadzu Corporation) with a 0.2% sodium hexametaphosphate aqueous solution as the dispersion medium, and measuring the average particle size (D50) on a volume basis.

[0155] [Table 2]

[0156] Table 2

[0157] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Glass 1 75.0 80.0 70.0 - - - - - - - - Glass 2 - - - 75.0 - - - - - - - Glass 3 - - - - 75.0 - - - - - - Glass 4 - - - - - 82.0 - - - - - Glass 5 - - - - - - 67.0 - - - - Glass 6 - - - - - - - 50.0 - - - Glass 7 - - - - - - - - 92.2 - - Glass 8 - - - - - - - - - 73.0 - Glass 9 - - - - - - - - - - 75.0 <![CDATA[CeO2]]> 25.0 20.0 30.0 25.0 25.0 18.0 33.0 50.0 7.8 2.0 25.0 <![CDATA[TiO2]]> - - - - - - - - - 25.0 - total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

[0158] (In the table, the amount of each component (various glasses, CeO2, and TiO2) is expressed in mass %.)

[0159] [Evaluation of dental porcelain materials]

[0160] The properties of the dental porcelain materials obtained in the Examples and Comparative Examples were evaluated by the following methods. The obtained results are shown in Table 3 below.

[0161] <Measurement of Transmittance of Dental Ceramics>

[0162] Porcelain powder was formed into pellets and fired at a maximum temperature of 930°C for 1 minute. The resulting test pieces were polished on both sides with #1000 water-resistant abrasive paper ("C947H" manufactured by Noritake Coated Abrasives) to produce measurement samples with a diameter of 11 mm and a thickness of 0.30 mm. The measurement was performed using a transmission densitometer, X-Rite (registered trademark) 361T(V) (manufactured by X-Rite), which was irradiated with light of a wavelength of 555 nm and measured for transmission density. The measured transmission density value was substituted into the following formula (1) to calculate the transmittance.

[0163] Transmittance [%] = 10 -透射浓度 ×100 (1)

[0164] In addition, more specifically, the calcination when making the aforementioned test piece was carried out under the following conditions: the drying time before calcination was 5 minutes; the calcination start temperature was 600°C; the heating rate was 45°C / minute; the vacuum start temperature was 600°C; the vacuum degree was 96 kPa; when the maximum calcination temperature reached 930°C, it was opened to atmospheric pressure (vacuum was released) and retained for 1 minute; after the retention, it was quickly cooled to room temperature (25°C).

[0165] <Evaluation of Lightness and Chroma of Dental Ceramics>

[0166] The test piece was formed into a pellet shape by molding the ceramic powder and calcining it at a maximum temperature of 930°C for 1 minute. It was then polished with #1000 water-resistant abrasive paper ("C947H" manufactured by Noritake Coated Abrasives) on both sides and finished to a diameter of 14 mm and a thickness of 1.20 mm. The test piece was measured using a spectrophotometer CM-3610A (manufactured by KONICA MINOLTA) under the conditions of D65 light source, SCI measurement mode, Measure on a white background and read L * a * b * Color system (JISZ 8781-4: 2013 Color measurement - Part 4: CIE 1976 L * a * b * Lightness (color space) in color space is L * Value and chroma representing hue and saturation, i.e. a * 、b * .

[0167] More specifically, the firing when preparing the test piece was performed under the same conditions as those described in the section on transmittance measurement of the dental ceramic material.

[0168] <Evaluation of Coloration of Dental Porcelain>

[0169] As a white porcelain, a color control sample, "CERBIAN (registered trademark) ZR Porcelain SB WHITE," was used as a comparison sample, and visual inspection was performed to confirm whether coloration was observed. The sample used for color comparison was the polished surface of the pellet shape used in the evaluation of lightness and chroma of dental porcelain.

[0170] When no coloring was observed, it was judged as "A evaluation: no coloring", and when coloring was observed, it was judged as "F evaluation: coloring".

[0171] <Determination of Thermal Expansion Coefficient of Dental Ceramics>

[0172] The coefficient of thermal expansion was measured in accordance with ISO 6872 (2015). The test specimens used in the measurement were prepared by polishing the upper and lower surfaces of a 20 mm long product formed from porcelain powder into a rod (diameter: 5 mm) and calcining it at a maximum calcination temperature of 930°C for 1 minute using both sides of #1000 water-resistant abrasive paper (Noritake Coated Abrasives, Inc., "C947H"). Using a TMA8310 thermomechanical analyzer (Rigaku Corporation), the change in length of the test specimens was measured at a heating rate of 10°C / minute over the temperature range of 25-500°C. The coefficient of thermal expansion within the temperature range of 30-450°C was calculated using the data (thermal expansion curve) from the temperature range of 30-450°C.

[0173] More specifically, the firing when preparing the test piece was performed under the same conditions as those described in the section on transmittance measurement of the dental ceramic material.

[0174] <Evaluation of the presence or absence of cracks>

[0175] Using calcined ZrO2 pellets containing a 3 mol% Y2O3 solid solution (referred to as "3Y" in Table 3 below) and calcined ZrO2 pellets containing a 6 mol% Y2O3 solid solution (referred to as "6Y" in Table 3 below), the presence of cracks in the ceramic was determined. Porcelain was applied to the two disc-shaped ZrO2 pellets and then fired at 930°C for 1 minute. The adherence of the ceramic to the fired pellets was then determined. If the ceramic adhered to the applied shape as is, it was rated "A: No Cracks." If the ceramic cracked or partially or completely peeled off from the fired pellets, it was rated "F: Cracks."

[0176] More specifically, the firing of the ceramic material after coating the fired pellets with the ceramic material was performed under the same conditions as those described in the transmittance measurement section of the dental ceramic material.

[0177] [Table 3]

[0178] Table 3

[0179]

[0180] (In the table, the content of each component in "Porcelain Composition" is expressed in mass %.)

[0181] The results in Table 3 show that the dental porcelain materials of Examples 1 to 7 have excellent masking properties, can suppress discoloration of the porcelain materials during firing, and can suppress the occurrence of cracks when sintered and bonded to a ceramic substrate.

[0182] On the other hand, it was found that the dental porcelain material of Comparative Example 1, which had an SiO 2 content of less than 30.0 mass % and contained no ZrO 2 , had a high thermal expansion coefficient and was prone to cracking.

[0183] Furthermore, it was found that the dental porcelain material of Comparative Example 2, in which the SiO 2 content exceeded 50.0 mass % and the CeO 2 content was less than 10.0 mass %, had high transmittance and poor shielding properties.

[0184] Furthermore, it was found that the dental porcelain material of Comparative Example 3, in which the CeO 2 content was less than 10.0 mass % and TiO 2 was also mixed as an opacifying agent, discolored (blackened) upon firing.

[0185] Furthermore, it was found that the dental porcelain material of Comparative Example 4, which did not contain ZrO 2 , changed color (yellowing) due to firing.

[0186] Industrial applicability

[0187] The dental porcelain material of the present invention can be used for dental prostheses and the like.

[0188] Furthermore, in recent years, particularly with the increasing demand for ceramic crowns and the improvement of personal aesthetic tastes, the frequency of use of dental ceramics is expected to increase. Therefore, the dental ceramic of the present invention is useful as a dental ceramic for a base material obtained using ceramics such as zirconia.

Claims

1. Dental porcelain material comprising SiO2, CeO2, ZrO2 and an oxide of an alkaline earth metal, The content of SiO2 is 30.0-50.0% by mass in 100% by mass of the dental porcelain material. The content of CeO 2 is 10.0 to 50.0 mass % in 100 mass % of the dental porcelain material.

2. The dental porcelain material according to claim 1, wherein: The content of ZrO2 is 5.0 to 16.0 mass % in 100 mass % of the dental porcelain material.

3. The dental porcelain material according to claim 1 or 2, further comprising Al2O3, K2O and Na2O, The content of Al2O3 is 2.0 to 8.0% by mass in 100% by mass of the dental porcelain material. The content of K2O is 1.0 to 7.0% by mass in 100% by mass of the dental porcelain material. The content of Na2O is 4.0 to 10.0 mass % in 100 mass % of the dental porcelain material.

4. The dental porcelain material according to any one of claims 1 to 3, wherein As the alkaline earth metal oxide, at least CaO and BaO are included. The content of CaO is 0.2 to 2.0% by mass in 100% by mass of the dental porcelain material. The content of BaO is 1.0 to 8.0 mass % in 100 mass % of the dental porcelain material.

5. The dental porcelain material according to any one of claims 1 to 4, wherein The total content of the SiO 2 , the CeO 2 , the ZrO 2 and the alkaline earth metal oxide is 70.0 to 95.0% by mass in 100% by mass of the dental porcelain material.

6. The dental porcelain material according to any one of claims 1 to 5, wherein The CeO 2 is CeO 2 derived from an opacifying agent.

7. The dental porcelain material according to any one of claims 1 to 6, wherein The thermal expansion coefficient of the calcined body obtained by calcining the dental porcelain at a maximum calcination temperature of 930°C at a heating rate of 10°C / min at 30-450°C was 7.8×10 -6 / ℃ or above and less than 10.0×10 -6 / ℃.

8. The dental porcelain material according to any one of claims 1 to 7, wherein The transmittance of light having a wavelength of 555 nm in the thickness direction of a measurement sample having a thickness of 0.30 mm, formed from a fired body obtained by firing the dental porcelain at a maximum firing temperature of 930° C., is 10.0% or less.

9. The dental porcelain material according to any one of claims 1 to 8, wherein A test piece having a thickness of 1.20 mm, formed by firing the dental porcelain at a maximum firing temperature of 930° C., was tested using L * a * b * The lightness L obtained by color measurement in color space * Above 90.

0.

10. A method for producing a dental prosthesis, comprising: The process of coating the dental porcelain material according to any one of claims 1 to 9 on a zirconia substrate; and a step of calcining the dental porcelain material at 880-980°C.

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