Dental porcelain paste containing inorganic salt

Abstract

To provide a dental porcelain paste that can maintain a consistent paste form even during long-term storage and produces almost no carbonization or bubbles during firing, even when containing organic components.SOLUTION: This dental porcelain paste, used for making dental prosthetic devices, includes a base glass (a) with an average particle size (D50) of 1-20 μm, hydrophobic silica particles (b) with an average primary particle size of 1-50 nm, an organic solvent (c) with a boiling point of 100-300°C, and inorganic salts (d).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a dental porcelain paste that is used for dental prosthetic devices such as artificial teeth, maintains a constant paste property even after long-term storage, and is excellent in operability. [Background technology]

[0002] There is a growing demand for core materials with low allergenicity, excellent strength, and aesthetic appeal, such as oxide ceramics (e.g., alumina and zirconia) and glass-ceramics (e.g., feldspar glass and lithium silicate glass), for the fabrication of dental prosthetic devices such as inlays, crowns, and bridges. In particular, with the advancement of CAD / CAM technology in recent years, techniques that allow for the shape of dental prosthetic devices to be achieved using a single material have become mainstream. However, despite advances in multilayering technology, oxide ceramics still suffer from low transparency, while glass-ceramics, while highly transparent, face the challenge of not being able to reproduce the specific color tone of natural teeth. Therefore, the current situation is that the material properties of these materials alone are insufficient to ensure aesthetic results. To achieve aesthetic results equivalent to those of natural teeth, companion materials that complement the gloss, transparency, and coloring are required.

[0003] Materials typically selected to impart gloss, transparency, and color to oxide ceramic or glass ceramic core materials include glass, glass ceramic, and oxide ceramic materials. These materials are typically prepared by kneading powdered base glass with a liquid component that disappears during baking to form a paste. In this case, it is preferable to prepare a paste (slurry) with a viscosity suitable for application in advance, so that it is not dependent on the skill of the technician. Patent Document 1 discloses an organic solvent containing 5 wt% or more of an ester compound that does not contain an aromatic ring and does not contain a polymerizable monomer as an example of a kneading liquid used in this technology. However, pastes prepared by simply mixing these kneading liquids with base glass undergo significant changes over long-term storage, including paste settling, liquid separation, and a decrease in consistency (viscosity) due to the glass and liquid blending over time. These changes over time can lead to a decrease in work efficiency and difficulty in maintaining consistent workability during precise dental laboratory work.

[0004] Such changes over time are caused by changes in the state of particles in the paste, specifically particle aggregation and sedimentation of particles and aggregates. To suppress these changes, one method is to separately add an organic polymer dispersant to disperse particles in the paste, thereby maintaining consistent paste properties even during long-term storage. Patent Document 2 discloses a dental paste-like porcelain that is resistant to drying and solidification during use. It is characterized by a paste-like structure, consisting of 7 to 45 parts by weight of an organic solvent with a viscosity of 50,000 to 1,500,000 cps, in which a polymeric material has been dissolved, mixed with the remainder of porcelain powder to a total of 100 parts by weight. However, this method can cause carbonization and bubble formation due to the influence of the organic polymer component during firing.

[0005] While the technique of preparing the paste in advance is useful, there are problems in that it is not possible to maintain a constant paste property over long-term storage, or in order to maintain a constant paste property, it is necessary to add a stabilizing component that may adversely affect gloss, transparency, and color tone. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2017-193492 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-079019 Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, an object of the present invention is to provide a dental porcelain paste that can maintain a constant paste property even when stored for a long period of time, and that hardly generates carbonization or bubbles during firing even when it contains organic components. [Means for solving the problem]

[0008] The present invention provides a dental porcelain paste for producing a dental prosthesis, characterized by comprising: (a) a base glass having an average particle size D50 of 1 to 20 μm; (b) hydrophobicized fine silica particles having an average primary particle size of 1 to 50 nm; (c) an organic solvent having a boiling point of 100 to 300°C; and (d) an inorganic salt.

[0009] In the present invention, the "average particle diameter D50" refers to the median diameter (middle diameter) that represents the average value of particles. The average particle diameter of the substrate glass can be determined by a measurement method using, for example, laser diffraction / scattering, dynamic light scattering, centrifugal sedimentation, electrical detector method, sieving, photon correlation spectroscopy, or the like. The substrate glass (a) of the present invention may have an average particle diameter D50 of 1 to 20 μm measured by any of the measurement methods, and can particularly have an average particle diameter D50 of 1 to 20 μm measured by laser diffraction / scattering.

[0010] In the present invention, the "average primary particle size" refers to the average value of all particle sizes in an unagglomerated state. The average primary particle size of the hydrophobized silica microparticles can be calculated from the specific surface area obtained by measurement using, for example, gas adsorption, mercury porosimetry, gas permeation, or bubble point method. The hydrophobized silica microparticle (b) of the present invention may have an average primary particle size of 1 to 50 nm measured by any of these measurement methods, and can particularly have an average primary particle size of 1 to 50 nm measured by the gas adsorption method. [Effects of the Invention]

[0011] The dental porcelain paste of the present invention maintains a constant paste property even when stored for a long period of time, and even if it contains organic components, it can suppress blackening due to carbonization during firing and cloudiness due to air bubbles. DETAILED DESCRIPTION OF THE INVENTION

[0012] The dental porcelain paste of the present invention is a dental porcelain paste for producing a dental prosthetic device, and comprises a base glass (a) having an average particle size D50 of 1 to 20 μm, hydrophobic fine silica particles (b) having an average primary particle size of 1 to 50 nm, an organic solvent (c) having a boiling point of 100 to 300°C, and an inorganic salt (d).

[0013] The dental porcelain paste of the present invention can contain 1 to 15 parts by mass of hydrophobic fine particle silica (b), 15 to 90 parts by mass of organic solvent (c), and 0.05 to 1.0 part by mass of inorganic salt (d) relative to 100 parts by mass of base glass (a).

[0014] The dental porcelain paste of the present invention may further contain a coloring material (e) and / or a fluorescent material (f), which are inorganic materials.

[0015] In the dental porcelain paste of the present invention, the maximum particle size D100 of the base glass (a) can be 200 μm or less.

[0016] Dental porcelain pastes are used by, for example, applying or building up on a core material and firing it one or more times. This allows the desired shape, luster, and color of the dental prosthetic device to be obtained. The "core material" in this invention can be, for example, oxide ceramics such as alumina and zirconia, or glass or glass ceramics such as feldspar glass and lithium silicate glass.

[0017] The temperature for firing dental porcelain paste (hereinafter referred to as firing temperature) is generally selected to be in the range of 650 to 1000°C. Firing at temperatures below 650°C may result in insufficient firing of the organic solvent, resulting in carbonization and failure to achieve the desired color tone. Firing at temperatures above 1000°C may result in deformation or sagging of the core material itself or the surface of the porcelain paste applied to the dental prosthetic device.

[0018] It is undesirable that the appropriate firing temperature for firing a dental porcelain paste (hereinafter referred to as the "appropriate firing temperature") deviates significantly from the appropriate firing temperature for the substrate glass (a) constituting the dental porcelain paste. In other words, when the dental porcelain paste is fired at the same temperature as the appropriate firing temperature for the substrate glass, it is preferable that the surface coated with the dental porcelain paste after firing is not insufficiently fired (loss of gloss). This is because the original properties of the substrate glass, such as firing ability and physical properties, are not lost when the paste is formed. In the present invention, the "appropriate firing temperature for a dental porcelain paste" refers to a temperature at which gloss can be imparted to the surface of the dental porcelain paste layer after firing, and may be a temperature range. Furthermore, in the present invention, the "appropriate firing temperature for a substrate glass" refers to a temperature at which gloss can be imparted to the surface of the substrate glass layer after firing, and may be a temperature range.

[0019] In the present invention, the appropriate firing temperature for the substrate glass (a) can be in the range of 650 to 1000°C. The appropriate firing temperature range is not particularly limited, but substrate glasses with appropriate firing temperatures below 650°C cannot be used because they are difficult to manufacture from the standpoints of aesthetics and biosafety. Substrate glasses with appropriate firing temperatures above 1000°C are not preferred because they may cause deformation or sagging of the core material itself or the surface on which the porcelain paste applied to the dental prosthetic device is applied.

[0020] The dental porcelain paste may be fired only once. Alternatively, the dental porcelain paste may be fired multiple times, for example, by building up a layer of dental porcelain paste and firing it, and then building up another layer of dental porcelain paste and firing it. Such firing can be carried out using a dental laboratory porcelain firing furnace capable of vacuum firing at a temperature rise rate of 10 to 100°C / min and in a firing temperature range of 100 to 1200°C.

[0021] The substrate glass (a) is a glass component that serves as the base material for the dental prosthetic device obtained by firing, and melts upon firing to adhere and bond to the core material. In the present invention, the substrate glass (a) can be used alone or in appropriate combination of two or more types, as long as it adheres to the core material upon firing.

[0022] The average particle diameter D50 of the substrate glass (a) is 1 to 20 μm, and can be 2 to 15 μm, or can be 4 to 10 μm. If the average particle diameter D50 is smaller than 1 μm, the glass particles may aggregate when pasted, resulting in a change in consistency. If the average particle diameter is larger than 20 μm, the substrate glass may be prone to settling when pasted.

[0023] In the present invention, "average particle diameter D50" refers to the median diameter (middle diameter), i.e., D50 / μm. Here, a D50 / μm value of X means that 50% of the particles in the analyzed volume have a diameter below X μm. "Average particle diameter D50" is different from other averaging methods (arithmetic mean of number, length, volume, area, etc.) and mode diameter (most frequent particle diameter).

[0024] The maximum particle size D100 / μm of the substrate glass can be 200 μm or less, 175 μm or less, or 100 μm or less. In the present invention, "maximum particle size D100" refers to the maximum particle size in the analyzed volume. If the substrate glass contains particles larger than 200 μm, operability is poor and the coating surface after firing tends to be uneven. Furthermore, the substrate glass tends to settle easily when made into a paste.

[0025] The method for producing the substrate glass can be carried out without limitation using general glass composition production equipment and methods owned by the relevant manufacturer. A typical production method involves blending various inorganic compounds to obtain the desired glass composition and melting them at 1300 to 1500°C in a glass melting furnace. The molten liquid is poured into water and rapidly cooled (quenched) to obtain glass frit. To use the substrate glass obtained by this method as a dental porcelain paste, the glass frit must be powdered to adjust the particle size. Examples of methods for powdering include grinding the aforementioned glass frit using a grinder such as a rotary ball mill, a vibrating ball mill, a planetary mill, a jet mill, a bead mill, a roll crusher, or a jaw crusher. Furthermore, in order to uniformly adjust the particle size of the substrate glass, in addition to grinding the substrate glass, classification may be performed using a sieve, elutriation, or the like, as needed.

[0026] The softening point (Ts) of the substrate glass (a) can be set to 450 to 650° C. By using a substrate glass with a softening point (Ts) of 450 to 650° C., firing at 650 to 850° C. becomes possible, and this enables application to core materials made of lithium disilicate glass ceramics, which may deform when fired at temperatures higher than 850° C.

[0027] The amount of base glass (a) can be appropriately adjusted so as to obtain the desired paste properties, but if the amount of base glass (a) is too small (if the amount of components other than base glass (a) is too large), the gloss and transparency inherent to the base glass (a) tend to be insufficient, and it tends to be difficult to maintain the paste properties, etc. Also, if the amount of base glass (a) is too large, it tends to be difficult to form a paste.

[0028] The substrate glass (a) used in the present invention can be used as a dental porcelain material, and is not particularly limited as long as it has an average particle size D50 of 1 to 20 μm. It may also be a glass ceramic containing crystals in the glass. The inclusion of crystals is expected to adjust the thermal expansion coefficient of the dental porcelain paste and improve its mechanical properties.

[0029] Examples of the substrate glass (a) include glass or glass ceramics containing SiO2 as the main component (the component with the highest content). Such glasses may contain Al2O3, BO3, ZnO, KO, Na2O, Li2O, ZrO2, CaO, MgO, etc. in addition to SiO2. Specific examples include amorphous potassium aluminosilicate glass, amorphous potassium borosilicate glass, crystalline potassium aluminosilicate glass, crystalline fluoroapatite glass, and crystalline lithium silicate glass.

[0030] The base glass (a) is the main component (the component with the highest content) of the dental porcelain paste of the present invention, and is the component that determines the material characteristics and physical properties of the dental porcelain paste itself. Therefore, the amount of elution, bending strength, and thermal expansion coefficient of the base glass (a) used in the present invention can be made suitable for use as a dental porcelain.

[0031] The substrate glass (a) used in the present invention has an elution amount of 50 μg / cm according to, for example, ISO6872:2015 / Amd.1:2018 "Dentistry-Ceramic materials". 2 can be less than or equal to 35 μg / cm 2can be less than 20 μg / cm 2 The elution amount can be 50 μg / cm or less. 2 By satisfying the following conditions, a dental porcelain paste that satisfies the requirements of the ISO standard can be obtained.

[0032] The substrate glass (a) used in the present invention may have a bending strength of 50 MPa or more, 80 MPa or more, or 100 MPa or more, in accordance with, for example, ISO6872:2015 / Amd.1:2018 "Dentistry-Ceramic materials." By making the bending strength 50 MPa or more, a dental porcelain paste that satisfies the required value of the ISO standard can be obtained.

[0033] The substrate glass (a) used in the present invention has a thermal expansion coefficient of 7.0 to 14.0 × 10 in accordance with, for example, ISO6872:2015 / Amd.1:2018 "Dentistry-Ceramic materials." -6 K -1 The range is 7.5 to 11.0 × 10 -6 K -1 The dental porcelain paste of the present invention is used for the purpose of adhering to the upper part of a core material made of, for example, oxide ceramics or glass ceramics. The thermal expansion coefficient of these core materials can be in the range of about 10.0 to 11.0 × 10 -6 K -1 Therefore, by setting the thermal expansion coefficients of the base glass and dental porcelain paste to a range slightly lower than this, it is possible to suppress the occurrence of cracks during the production of dental prosthetic devices.

[0034] The average primary particle diameter of the hydrophobicized silica microparticle (b) is 1 to 50 nm, can be 5 to 45 nm, and can be 7 to 40 nm. If the average primary particle diameter of the hydrophobic silica microparticle (b) is greater than 50 nm, the paste consistency may change. Hydrophobic silica microparticles with an average primary particle diameter of less than 1 nm cannot be used because the production of the microparticle silica itself is difficult.

[0035] The hydrophobicized silica fine particle (b) is hydrophobized by surface treatment with a surface treatment agent. Examples of the surface treatment agent include silane coupling agents. Examples of the silane coupling agent include, but are not limited to, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, 3,3,3-trifluoropropyltrimethoxysilane, methyl- 3,3,3-Trifluoropropyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, hexamethyldisilazane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, polydimethylsiloxane, 3-methacryloxypropylmethyldiethoxysilane, N-2(aminoethyl)3-aminopropylmethyldimethoxysilane Sisilane, N-2(aminoethyl)3-aminopropyltrimethoxysilane, N-2(aminoethyl)3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, trimethylsilanol, methyltrichlorosilane, methyldichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyl Examples of such silanes include dichlorosilane, vinyltrichlorosilane, trimethylbromosilane, diethylsilane, vinyltriacetoxysilane, ω-(meth)acryloxyalkyltrimethoxysilane (number of carbon atoms between the (meth)acryloxy group and the silicon atom: 3 to 12, e.g., 3-methacryloxypropyltrimethoxysilane), and ω-(meth)acryloxyalkyltriethoxysilane (number of carbon atoms between the (meth)acryloxy group and the silicon atom: 3 to 12, e.g., 3-methacryloxypropyltriethoxysilane).Examples of surface treatment methods include contacting a silane coupling agent with particulate silica. Specifically, particulate silica is placed in a heated reactor, and an inert gas such as nitrogen is used to co-pump the silane coupling agent into the reactor at a ratio of 0.01 to 0.5 kg per 1 kg of silica. In the present invention, silica other than hydrophobized particulate silica, such as hydrophilic silica, may be included as long as it does not affect the effects of the present invention. Specifically, in the present invention, the proportion of silica other than hydrophobized particulate silica may be 0 wt% to 50 wt%, 0 wt% to 20 wt%, or 0 wt% to 10 wt% of the total amount of silica. Furthermore, in the present invention, silica other than hydrophobized particulate silica may be omitted.

[0036] The hydrophobic silica particulate (b) can be appropriately blended according to the desired paste properties, but can be 1 to 15 parts by mass, or 1.5 to 6.0 parts by mass, per 100 parts by mass of the substrate glass (a). If the amount of hydrophobic silica particulate (b) is too small, the paste consistency may change. If the amount of hydrophobic silica particulate (b) is too large, the dental porcelain paste becomes difficult to fire, and when the dental porcelain paste is fired at the appropriate firing temperature for the substrate glass, the loss of gloss due to insufficient firing may occur. Furthermore, it may be difficult to apply the paste evenly.

[0037] The hydrophobic silica fine particle (b) used in the present invention is not particularly limited as long as it has an average primary particle diameter of 1 to 50 nm, and examples thereof include fumed silica, precipitated silica, colloidal anhydrous silica, silica gel, syloid, aerosil, etc. These hydrophobic silica fine particle (b) may be used alone or in appropriate combination of two or more.

[0038] The organic solvent (c) used in the present invention has a boiling point of 100 to 300°C. If the boiling point of the organic solvent is less than 100°C, the organic solvent will volatilize even at room temperature, making it difficult to handle during dental prosthesis work and maintaining the paste properties over the long term. If the boiling point of the organic solvent exceeds 300°C, the organic solvent will remain unburned during firing, causing carbonization and bubbles.

[0039] In the present invention, the amount of organic solvent (c) can be 15 to 90 parts by mass, or 30 to 60 parts by mass, per 100 parts by mass of the substrate glass. If the amount of organic solvent is too small, it becomes difficult to form a paste. If the amount of organic solvent is too large, changes in consistency and sedimentation tend to occur over time.

[0040] The organic solvent (c) used in the present invention is not particularly limited as long as it has a boiling point of 100 to 300°C. Examples thereof include ester solvents such as dimethyl phthalate and diethyl phthalate; polyhydric alcohol solvents such as 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, glycerin, diethylene glycol, triethylene glycol, propylene glycol, and dipropylene glycol; polyhydric alcohol monoether solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monopropyl ether, tripropylene glycol monomethyl ether, diethylene glycol monobutyl ether, and triethylene glycol monomethyl ether; and aromatic alcohol solvents such as 2-phenoxyethanol and benzyl alcohol. Among these organic solvents, polyhydric alcohol solvents, polyhydric alcohol monoether solvents, and aromatic alcohol solvents can be used, such as 1,3-butanediol, propylene glycol, and 2-phenoxyethanol. These organic solvents (c) can be used alone or in appropriate combinations of two or more. When two or more organic solvents are used in combination, the boiling point is calculated by multiplying the boiling point of each organic solvent by the addition ratio and adding them together.

[0041] Furthermore, the organic solvent (c) used in the present invention may be an alcohol having a hydroxy group, which improves compatibility with the substrate glass having a hydroxy group and improves coating properties.

[0042] The dental porcelain paste of the present invention may be free of water except when adsorbed onto particles such as base glass or fine silica particles. The dental porcelain paste of the present invention may be free of water as a solvent.

[0043] The dental porcelain paste of the present invention may be free of organic polymer solvents. In the present invention, "organic polymer" refers to an organic component with a molecular weight of 200 or more, which is added separately for purposes other than surface treatment. Such organic components have poor volatility and may remain after firing. The dental porcelain paste of the present invention may be free of any solvent other than the organic solvent (c).

[0044] The dental porcelain paste of the present invention can contain additives that stabilize the particle state. These additives include dispersants, surfactants, and pH adjusters. However, when used as dental porcelain, if any of these additives remain after the firing process, they will have a significant impact on the aesthetics. For this reason, the additives used in the present invention can be dissolved in organic solvents and converted into inorganic salts that leave little residue after firing.

[0045] The inorganic salt (d) may be one that volatilizes during firing of the dental porcelain paste, or one that remains as a metal oxide similar to a constituent of the base glass (a).

[0046] The inorganic salt (d) used in the present invention is not particularly limited, but may be one that is soluble in the organic solvent (c). Examples include chlorides, nitrates, sulfates, carbonates, and / or hydrates thereof, each composed of an element selected from Al, Zn, K, Na, Li, Ca, and Mg. Further specific examples include aluminum chloride, aluminum nitrate, zinc chloride, zinc nitrate, potassium chloride, potassium sulfate, sodium chloride, sodium sulfate, lithium chloride, lithium nitrate, calcium chloride, calcium nitrate, calcium sulfate, magnesium nitrate, magnesium sulfate, and / or hydrates thereof. These inorganic salts (d) may be used singly or in combination of two or more.

[0047] In the present invention, "solubility in organic solvent" refers to the property of dissolving 1.0 part by mass or less of an inorganic salt in 15 parts by mass of an organic solvent. This can be determined by a general solubility measurement method. For example, when 1.0 part by mass of an inorganic salt is added to 15 parts by mass of an organic solvent, if no undissolved inorganic salt remains in the organic solvent, the inorganic salt can be determined to be soluble in the organic solvent. Furthermore, dissolution in the organic solvent does not need to occur instantaneously; it may be possible to dissolve the inorganic salt by external force such as ultrasonic vibration, physical crushing, or heating.

[0048] In the present invention, the amount of inorganic salt (d) may be 0.05 to 1.0 parts by mass, or 0.1 to 0.5 parts by mass, per 100 parts by mass of the base glass (a). If the amount of inorganic salt (d) is too small, the consistency tends to change easily over time. If the amount is too large, dilatancy may be strongly expressed, which may affect operability.

[0049] The dental porcelain paste of the present invention must contain a base glass (a), hydrophobized silica microparticles (b), an organic solvent (c), and an inorganic salt (d). Furthermore, in order to suppress changes in the consistency of the paste over time, the dental porcelain paste of the present invention may contain, particularly, 1 to 15 parts by mass of hydrophobized silica microparticles (b) and 0.05 to 1.0 part by mass of inorganic salt (d) per 100 parts by mass of the base glass (a). The dental porcelain paste of the present invention may contain 1.5 to 6.0 parts by mass of hydrophobized silica microparticles (b) and 0.1 to 0.5 parts by mass of inorganic salt (d) per 100 parts by mass of the base glass (a). The dental porcelain paste of the present invention may contain 1 to 15 parts by mass of hydrophobized silica microparticles (b), 15 to 90 parts by mass of organic solvent (c), and 0.05 to 1.0 part by mass of inorganic salt (d) per 100 parts by mass of the base glass (a). The dental porcelain paste of the present invention can contain 1.5 to 6.0 parts by mass of hydrophobized fine silica particle (b), 30.0 to 60.0 parts by mass of an organic solvent, and 0.1 to 0.5 parts by mass of an inorganic salt, relative to 100 parts by mass of a base glass (a).

[0050] The dental porcelain paste of the present invention may contain a coloring material (e) and / or a fluorescent material (f). Examples of the coloring material (e) include inorganic materials commonly used in dental materials. Specific examples include coloring materials prepared by mixing and firing multiple metal oxides, such as SiO2, Al2O3, CaO, TiO2, SnO, Cr2O3, MnO, Sb2O3, VO5, ZnO, Fe2O3, W2O3, Co2O3, and ZrO2. The preferred blending amount of the coloring material (e) is 0.05 to 40 wt% of the total dental porcelain paste, taken as 100.0 wt%.

[0051] The fluorescent material (f) may be, for example, an inorganic material typically used in dental materials. Its blending amount is preferably in the range of 0.1 to 5.0 wt% when the total dental porcelain paste is taken as 100.0 wt%. The coloring material (e) and / or fluorescent material (f) may be inorganic. In the present invention, burnable organic dyes may be excluded. This is because, like organic polymers, they remain during the firing stage and cause bubbles to form.

[0052] The dental porcelain paste of the present invention can be produced without limitation by a general paste composition production method possessed by the relevant manufacturer. A general production method is to blend base glass, hydrophobicized silica particulates, organic solvent, inorganic salt, colorant, and fluorescent material so as to obtain the desired paste composition, and mix them in a device equipped with stirring and / or degassing functions to obtain a paste. This can be done by a known kneading method using a rotary mixer equipped with stirring blades, a planetary mixer, a crusher, a roll mill, a ball mill, a kneader, or the like, and these methods can be used alone or in combination. [Example]

[0053] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples and comparative examples in any way.

[0054] The average particle size D50 and maximum particle size D100 of the substrate glass, the presence or absence of crystals, the appropriate firing temperature, the average primary particle size of the hydrophobicized silica microparticles, and various evaluation methods for the dental porcelain paste in the examples and comparative examples are shown below.

[0055] [Measuring method for average particle size D50 and maximum particle size D100 of substrate glass] The average particle size D50 and maximum particle size D100 of the substrate glass can be determined by measurements using laser diffraction / scattering, dynamic light scattering, centrifugal sedimentation, electrical detector method, sieving, photon correlation spectroscopy, etc. The particle sizes of the glass powders in the examples and comparative examples were measured by laser diffraction / scattering. Specifically, they were measured using a laser diffraction particle size distribution analyzer, Microtrac MT-3000II (manufactured by Microtrac Bell).

[0056] [Method for measuring the presence of crystals in the substrate glass] The presence or absence of crystals in the substrate glass can be confirmed by measurement using an X-ray diffractometer. Specifically, an X-ray diffractometer Multiflex (manufactured by Rigaku) ​​was used, and measurements were performed in a scanning range of 10 to 70° and at a scanning speed of 2.0° / min.

[0057] [Method for measuring the appropriate firing temperature for base glass] A paste was prepared by kneading the base glass with 1,3-butanediol. This paste was then applied to a 10.0 x 10.0 x 2.0 mm zirconia plate using a dental laboratory brush to a thickness of 0.2 mm. Vacuum firing was performed using an Esthemat Slim dental laboratory porcelain firing furnace (manufactured by Matsukaze). The lowest temperature at which the applied surface of the fired product developed a gloss was determined to be the optimum firing temperature for that base glass. The optimum firing temperatures for the base glass are shown in Table 2.

[0058] [Method for measuring softening point and thermal expansion coefficient of substrate glass] Each substrate glass was mixed with distilled water, and the mixture was filled into a silicone rod mold (6 x 6 x 25 mm). The mixture was repeatedly condensed and absorbed to produce a molded body. The molded body was removed from the silicone mold and subjected to two firings: one in vacuum and one in air, using a dental porcelain firing furnace, Esthemat Slim (Matsufu). Both ends of the resulting twice-fired body were polished to create parallel surfaces, and a sample measuring 5 x 5 x 20 mm was prepared. The thermal expansion coefficient and softening point were measured using a thermal dilatometer TM8140C (Rigaku) ​​according to the procedures in ISO 6872:2015 / Amd.1:2018, "Dentistry - Ceramic materials."

[0059] [Method for measuring the amount of elution from the substrate glass] Each substrate glass was mixed with distilled water, and the mixture was filled into a silicon disk (φ12mm x 2mm) mold. The mixture was then repeatedly condensed and absorbed to produce a molded body. The molded body was removed from the silicon mold and vacuum-fired using an Esthemat Slim dental porcelain firing furnace (manufactured by Matsukaze Co., Ltd.). Ten fired bodies were then produced. Both sides of the fired bodies were polished flat, and then a second air firing was performed. These specimens were then tested in accordance with the procedures of ISO6872:2015 / Amd.1:2018 "Dentistry - Ceramic materials."

[0060] [Method for measuring the bending strength of substrate glass] Each substrate glass was mixed with distilled water, and the mixture was filled into a silicone rod-shaped mold (3 x 6 x 25 mm). The mixture was then repeatedly condensed and absorbed to produce a molded body. The molded body was removed from the silicone mold and vacuum-fired using an Esthemat Slim dental porcelain firing furnace (Matsufu) to produce 10 fired bodies. The entire surface of the resulting fired body was polished to create parallel surfaces, and the specimens were adjusted to a size of 1.2 x 4 x 20 mm. The bending strength of these specimens was measured using a universal testing machine (Shimadzu) in accordance with the procedure of ISO 6872:2015 / Amd.1:2018, "Dentistry - Ceramic materials."

[0061] [Method for measuring the average primary particle size of hydrophobic silica fine particles] The average primary particle diameter of the hydrophobized silica microparticles can be calculated from the specific surface area obtained by measurement using a gas adsorption method, mercury intrusion porosimetry, gas permeation method, bubble point method, etc. The primary particle diameter of the hydrophobized silica microparticles in the examples and comparative examples was measured by the gas adsorption method. Specifically, the measurement was performed using an automatic specific surface area / pore distribution analyzer "Tristar II 3020" (manufactured by Shimadzu Corporation).

[0062] [Evaluation 1: Firing property at the appropriate firing temperature of the base glass (blackening)] The dental porcelain paste was applied to a thickness of 0.2 mm on the 10.0 x 10.0 mm surface of a zirconia plate (10.0 x 10.0 x 2.0 mm) using a dental laboratory brush. Vacuum firing was performed at the appropriate firing temperature (minimum temperature) for the base glass used using a dental laboratory porcelain firing furnace, Esthemat Slim (manufactured by Matsukaze). The firing properties (blackening) of the coated surface of the fired product produced by this method were evaluated. The evaluation criteria are shown below. A: A state in which the glass layer is transparent. In the case of Example 4 having a color tone, the color is sufficiently developed. B: Blackening due to carbonization occurs, and a decrease in brightness is observed in the glass layer.

[0063] [Evaluation 2: Bubbles in the paste] One spot on the coated surface of the fired product prepared in Evaluation 1 was observed and evaluated in a 100 μm×100 μm field of view. The evaluation criteria are shown below. A: Less than 10 bubbles of 5 μm or larger are observed. B: More than 10 bubbles larger than 5 μm are observed.

[0064] [Evaluation 3: Consistency and change of paste] In this evaluation, after preparing the paste, 5 g was filled into an 8 mL cream container and stored at 23°C for 1 and 14 days, and at 50°C for 14 days. The paste was left in a constant temperature room at 23°C for one hour before the evaluation. A weight of 0.3±0.03g was weighed onto a glass plate, and another glass plate was placed on top, with a 20g weight placed on top. 30 seconds after the weight was placed on top, the weight was removed, and the paste that spread into a circle was used to measure the consistency and amount of change. Two samples were measured for each paste, and their maximum and minimum diameters were measured. The consistency was calculated by averaging the four values, consisting of the maximum and minimum diameters of the two measurement samples. The consistency of the paste stored at 23°C for 1 day was taken as the initial value, and the difference in consistency from the initial value of the paste stored at 23°C for 14 days and at 50°C for 14 days was calculated, and the larger difference was taken as the amount of change. The evaluation criteria are as follows: AA: The amount of change is 0 to 2 mm. It can be determined that the consistency of the paste does not change over time. A: The change is 3 to 4 mm. It can be determined that the consistency of the paste hardly changes over time. B: The amount of change is 5 to 9 mm. It can be determined that the consistency of the paste changes over time. C: The change is 10 mm or more. It can be determined that the consistency of the paste changes significantly over time.

[0065] [Rating 4: Settling of paste] For this evaluation, after preparing the paste, 5 g was filled into an 8 mL cream container and stored at 50°C for 14 days. One hour before the evaluation, the product was left in a thermostatic chamber at 23°C, and the paste in the cream container was stirred with a plastic spatula to check for any settling of the paste. The evaluation criteria are as follows: A: No settling of the paste is observed. Stir for 15 seconds until the paste becomes homogeneous. B: Settling of the paste is observed. Stir for 15 seconds until the paste becomes homogeneous. C: Settling of the paste is observed. Even after stirring for 15 seconds or more, lumps remain and the paste does not become uniform.

[0066] [Evaluation 5: Firing property (gloss) at the appropriate firing temperature of the base glass] The baking properties (gloss) of the coated surface of the baked product prepared in Evaluation 1 were evaluated. AA: The surface of the baked product is glossy and has a uniform coating. A: The surface of the fired product has a glossy finish, but there are uneven spots (brush lines) all over the surface. B: Due to insufficient firing, the surface of the fired product lacks luster and is unevenly coated overall.

[0067] [Base glass] Glasses G1 to G3 containing SiO2, Al2O3, KO, Na2O, and other components (BO3, Li2O, CaO, ZnO, etc.) in the proportions shown in Table 1 were prepared by a melting method and then crushed in a conventional crusher to produce substrate glasses (a-1) to (a-11). Vintage Art Universal (manufactured by Shofu) AS (A shade), a commercially available coloring material for dental ceramics, was used as substrate glass (a-12). In addition to the substrate glass components, substrate glass (a-12) also contains a colorant (e) selected from inorganic materials and a fluorescent material (f) selected from inorganic materials. Its average particle size D50 is 5 μm, its maximum particle size D100 is 75 μm, and its optimum firing temperature is 730°C. Details of each substrate glass are as follows:

[0068] [Table 1]

[0069] <Production of substrate glass (a-1)> Glass G1 was pulverized in a bead mill until D50 was 0.5 μm.

[0070] <Production of substrate glass (a-2)> Glass G1 was pulverized in a bead mill until D50 was 1.0 μm.

[0071] <Production of substrate glass (a-3)> Glass G1 was pulverized in a bead mill until D50 was 2.0 μm.

[0072] <Production of substrate glass (a-4)> Glass G1 was pulverized in a vibration ball mill until D50 was 4.0 μm.

[0073] <Production of substrate glass (a-5)> Glass G1 was pulverized in a vibration ball mill until D50 was 6.0 μm.

[0074] <Production of substrate glass (a-6)> Glass G1 was pulverized in a vibration ball mill until D50 was 10.0 μm.

[0075] <Production of substrate glass (a-7)> Glass G1 was pulverized in a ball mill until D50 was 15.0 μm.

[0076] <Production of substrate glass (a-8)> Glass G1 was pulverized in a ball mill until D50 was 20.0 μm.

[0077] <Production of substrate glass (a-9)> Glass G1 was pulverized in a ball mill until D50 was 40.0 μm.

[0078] <Production of substrate glass (a-10)> Glass G2 was pulverized in a vibration ball mill until D50 was 6.0 μm.

[0079] <Production of substrate glass (a-11)> Glass G3 was subjected to a heat treatment process to precipitate leucite crystals, and then pulverized in a jet mill pulverizer until D50 was 5.0 μm.

[0080] Table 2 shows the test results for each substrate glass.

[0081] [Table 2]

[0082] [Fine particle silica] The fine particle silica particles used were RX50 (average primary particle diameter 40 nm, manufactured by Nippon Aerosil Co., Ltd.), R974 (average primary particle diameter 12 nm, manufactured by Nippon Aerosil Co., Ltd.), R812 (average primary particle diameter 7 nm, manufactured by Nippon Aerosil Co., Ltd.), YA050C (average primary particle diameter 50 nm, manufactured by Admattex Co., Ltd.), YA100C (average primary particle diameter 100 nm, manufactured by Admattex Co., Ltd.), and hydrophilic fine particle silica #200 (manufactured by Nippon Aerosil Co., Ltd.).

[0083] [Organic solvents] As the organic solvent, ethanol, propylene glycol, 1,3-butanediol, glycerin, and benzyl benzoate were used.

[0084] [water] Water was used as the liquid component other than the organic solvent.

[0085] [Table 3]

[0086] [Inorganic salts] The inorganic salts used were calcium chloride, zinc chloride, and calcium nitrate tetrahydrate, which are soluble in all of the above organic solvents.

[0087] [Organic polymer salts] As the organic polymer salts, sodium polyacrylate (molecular weight 5,000) and sodium carboxymethylcellulose (molecular weight 700,000), which are soluble in all of the above organic solvents, were used.

[0088] [Table 4]

[0089] [Table 5]

[0090] [Table 6]

[0091] In Examples 1 to 31, there were no problems with the sinterability of the paste, changes in consistency over time, or the occurrence of sedimentation.

[0092] On the other hand, the comparative example had the following problems. In Comparative Examples 1 and 2, the average particle diameter D50 of the substrate glass was not appropriate, and therefore, large changes in consistency and sedimentation occurred over time. In Comparative Examples 3 and 4, hydrophobic fine particle silica or hydrophilic fine particle silica with an inappropriate average primary particle size was used, and therefore sedimentation occurred over time. Comparative Examples 5 and 10, which did not contain inorganic salts, caused large changes in consistency. In Comparative Examples 6 and 7, since only ethanol or only benzyl benzoate was used as the organic solvent, sedimentation occurred over time and the coated surface turned black. In Comparative Examples 8 and 9, the use of an organic polymer component caused blackening and bubbles on the coated surface.

[0093] From the above results, it can be seen that the dental porcelain paste of the present invention maintains a constant paste property even when stored for a long period of time, and even if it contains organic components, it becomes a paste that suppresses blackening due to carbonization and cloudiness due to air bubbles during firing, thereby significantly improving the problems of the prior art. [Industrial Applicability]

[0094] The dental porcelain paste provided by the present invention has storage stability, allowing it to maintain a constant paste property for a long period of time, and is also excellent in application properties and aesthetics. Therefore, it can be applied to various crown restorations in restorative dental treatment.

Claims

1. A dental porcelain paste for producing a dental prosthetic device, comprising: A substrate glass (a) having an average particle diameter D50 of 1 to 20 μm; (b) hydrophobized fine silica particles having an average primary particle diameter of 1 to 50 nm; (c) an organic solvent having a boiling point of 100 to 300°C; and Inorganic salt (d) Including, A dental porcelain paste comprising 0.05 to 1.0 parts by mass of an inorganic salt (d) per 100 parts by mass of a substrate glass (a).

2. With respect to 100 parts by mass of the substrate glass (a), 1 to 15 parts by mass of hydrophobized fine silica particles (b), 15 to 90 parts by weight of an organic solvent (c) 2. The dental porcelain paste of claim 1, comprising:

3. 2. The dental porcelain paste according to claim 1, further comprising a coloring material (e) and / or a fluorescent material (f) which are inorganic materials.

4. 3. The dental porcelain paste according to claim 2, further comprising a coloring material (e) and / or a fluorescent material (f) which are inorganic materials.

5. 5. The dental porcelain paste according to claim 1, wherein the maximum particle size D100 of the base glass (a) is 200 μm or less.