Dental glass composition

Abstract

The present invention provides a dental glass composition which exhibits excellent fixability to dental prostheses and does not require firing for fixation, and which is capable of suppressing the generation of excessive air bubbles and the occurrence of interfacial debonding at the interface between a base material and a dental ceramic material in cases where firing for fixation is not carried out, while making it possible to build up and fire a dental ceramic material thereon. The present invention relates to a dental glass composition which contains a glass powder (A) and a binder, wherein the binder contains a hydrophilic organic compound (B) that is in a solid state at 25°C, while substantially containing no water and no propylene glycol.

Description

[Technical Field]

[0001] The present invention relates to a dental glass composition used for coloring and adjusting the color tone of dental prostheses. More specifically, the present invention relates to a dental glass composition suitable for use in, for example, crowns, inlays, bridges, implant superstructures, dentures, and artificial teeth, which are made using ceramic raw materials, and in particular to a dental glass composition suitable as a color-adjusting composition for ceramic crown porcelain (hereinafter sometimes referred to as "porcelain stain"). [Background technology]

[0002] Dental prostheses (e.g., veneers, crowns, dentures, etc.) that restore aesthetics close to those of natural teeth include ceramic dental prostheses such as metal-ceramic dental prostheses and all-ceramic dental prostheses, which use dental porcelain that expresses the color tone of ivory or enamel on various materials such as metal, zirconium oxide (zirconia), aluminum oxide (alumina), feldspar glass, and disilicate glass.

[0003] In manufacturing ceramic dental prostheses, there is a technique for imitating the color tone of individual natural teeth by expressing the white bands, dentin, cervical and approximal surface coloration, hairlines, enamel cracks, etc. of natural teeth in the dental prosthesis. In this case, for example, porcelain stain is applied to the dental prosthesis, which makes the ceramic dental prosthesis more likely to blend in with the color tone of the natural teeth surrounding the tooth to which the dental prosthesis is applied.

[0004] When using a porcelain stain, a porcelain stain of an appropriately selected color tone is dispensed onto a glass mixing board or stain palette. Porcelain stains are generally provided in the form of powder or paste. When the porcelain stain is in powder form, an appropriate amount of the powder must be dispensed onto a glass mixing board or stain palette, and then water or a special liquid must be added to impart applicability to the powder, adjusting the powder-liquid ratio and other factors to form a paste. Even when the porcelain stain is in the form of a paste, the paste properties can change over time, such as during storage or after an appropriate amount of the paste has been dispensed onto a glass mixing board or stain palette, resulting in application problems such as increased viscosity, making it difficult to apply during use, and causing bleeding during application. Therefore, there is a demand for a porcelain stain that is easy to use and has excellent application properties.

[0005] Common techniques for coloring ceramic dental prostheses to mimic natural teeth include the "internal staining method," in which a porcelain stain is sandwiched between enamel-representing porcelain and dentin-representing porcelain, and the "surface staining method," in which a porcelain stain is applied to the outermost surface of the enamel-representing porcelain.

[0006] In these methods, in order to fuse the inorganic pigment components contained in the porcelain stain to the dental prosthesis and, in the case of the internal stain method, to prevent any influence on subsequent porcelain build-up using a different porcelain, it is essential to apply the porcelain stain to the dental prosthesis and then perform firing (hereinafter sometimes referred to as "fixing firing") using a dental laboratory porcelain firing furnace according to a firing schedule optimal for each porcelain stain. Since multiple firings are required to manufacture a dental prosthesis, there is a demand for porcelain stains that can shorten the manufacturing process.

[0007] As a color-adjusting composition for ceramic dental crown porcelain, for example, Patent Document 1 discloses a powder or paste-like porcelain stain containing a specific aluminosilicate glass. Also, Patent Document 2 discloses a paste that does not require firing before applying a body porcelain layer, by brushing a coating material consisting of an opaque porcelain powder and an aqueous colloidal dispersion of a urethane polymer onto a dental coping and air-drying it for 20 minutes before applying the body porcelain layer. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-207743 [Patent Document 2] Japanese Patent Application Publication No. 59-196807 Summary of the Invention [Problem to be solved by the invention]

[0009] However, in Patent Document 1, it is necessary to apply the porcelain stain in a paste state, and the paste must be prepared by mixing powder and liquid (e.g., water) each time it is used, and it has been found that it is not easy to adjust the viscosity; if the viscosity is too high, it is difficult to apply, and if the paste viscosity is too low, it bleeds when applied. Also, even when the paste-type porcelain stain described in Patent Document 1 is used, there is a problem in that the viscosity increases over time, changing the paste properties and making it difficult to apply.

[0010] Furthermore, in Patent Document 1, when applying multiple coats of paint, both the internal staining method and the surface staining method require firing each time, and the internal staining method requires firing to fix the porcelain stain before building up the porcelain on the surface, which poses the problem of requiring many steps.If the fixing firing is not performed, it has been found that problems such as the porcelain stain being unintentionally mixed with the porcelain to be built up subsequently, or the color of the porcelain stain bleeding out of the built-up porcelain before or during firing because the porcelain stain is not fixed, can occur.

[0011] Furthermore, in Patent Document 2, the contained urethane polymer cannot be completely burned under the firing conditions of the porcelain, resulting in carbonization and the generation of bubbles, and the technique of Patent Document 2 makes it difficult to achieve uniform application. In particular, the generation of bubbles is problematic because it adversely affects the firing of the porcelain to the coping (frame / substrate / base material). Furthermore, Patent Document 2 requires air drying for 20 minutes, which is longer than the time generally required for this process (5 to 8 minutes), and is therefore unrealistic from the standpoint of the time required for the process.

[0012] Therefore, an object of the present invention is to provide a dental glass composition that has excellent adhesion to dental prostheses, allows coloring to be layered without the need for a fixing firing, and, even when a fixing firing is not performed, can suppress the occurrence of significant bubbles and interfacial peeling at the interface between the substrate and dental porcelain, and allows dental porcelain to be built up and fired thereon. [Means for solving the problem]

[0013] As a result of extensive research into solving the above problems, the inventors have discovered that a dental glass composition containing a glass component and a hydrophilic organic compound that is solid at 25°C, and substantially free of water and propylene glycol, can be applied directly to a dental prosthesis without preparing a paste, and that a dental prosthesis having a desired color tone can be obtained without performing the fixing and firing step that is essential for the internal stain method, and that the generation of bubbles can be suppressed.Further research led to the completion of the present invention.

[0014] The present invention includes the following inventions. [1] Glass powder (A) and a binder, the binder comprises a hydrophilic organic compound (B) that is solid at 25°C; A dental glass composition that is substantially free of water and propylene glycol. [2] The dental glass composition according to [1], wherein the glass powder (A) has an average particle size of 0.05 μm to 50 μm. [3] The dental glass composition according to [1] or [2], wherein the melting point of the hydrophilic organic compound (B) is 35°C or higher. [4] The dental glass composition according to any one of [1] to [3], wherein the hydrophilic organic compound (B) is a water-soluble polymer. [5] The dental glass composition according to any one of [1] to [4], wherein the content of the hydrophilic organic compound (B) is 1 to 50 mass %. [6] The dental glass composition according to any one of [1] to [5], wherein the binder further contains an unsaturated fatty acid component (C) that is liquid at 25°C. [7] The dental glass composition according to [6], wherein the content of the unsaturated fatty acid component (C) is 0.5 to 30% by mass. [8] The dental glass composition according to any one of [1] to [7], wherein the binder further contains a wax component (D) that is solid at 25°C. [9] The dental glass composition according to any one of [1] to [8], wherein the contents of water and propylene glycol are less than 1000 ppm by mass.

[10] The dental glass composition according to any one of [1] to [9], which is solid at 25°C.

[11] The dental glass composition according to any one of [1] to

[10] , which is a porcelain stain.

[12] A method for manufacturing a dental prosthesis, comprising the steps of: applying the dental glass composition according to any one of [1] to

[11] to a substrate of a dental prosthesis having a ceramic surface; and firing the substrate after the dental porcelain is built up, without firing the substrate after the dental glass composition is applied and before the dental porcelain is built up.

[13] The method for manufacturing a dental prosthesis according to

[12] , wherein the firing temperature in the firing step after building up the dental porcelain is 700 to 1100°C. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a dental glass composition that has excellent fixability to dental prostheses, allows coloring to be layered without the need for a fixing firing, and, even when a fixing firing is not performed, can suppress the occurrence of significant bubbles and interfacial peeling at the interface between the substrate and the dental porcelain, and allows the dental porcelain to be built up and fired thereon. Furthermore, the dental glass composition of the present invention has excellent adhesion even when multiple coatings are performed, without requiring a fixing firing, and does not mix with the dental porcelain to be built up subsequently. This prevents the color tone of the dental glass composition from flowing out of the built-up dental porcelain before or during firing. Furthermore, the dental glass composition of the present invention does not require fixing or baking, which shortens the manufacturing process and is industrially advantageous. Furthermore, the dental glass composition of the present invention has excellent color development properties, so that coloring can be layered and a desired color tone can be adjusted.

[0016] Furthermore, the dental glass composition of the present invention is inhibited from changing over time, has excellent operability, allows for thin film application to dental prostheses, and, because it has no fluidity, can be applied without bleeding. Furthermore, the dental glass composition of the present invention can be used alone for dental prostheses. In addition, it is also possible to impart a gradation from the cervical region to the incisal edge using a brush or a sponge such as an eye color chip, or to blend the color using a finger, thereby enabling dental prostheses having a desired color tone to be easily produced with good operability. Furthermore, since subsequent porcelain building can be done without performing a fixing firing and the occurrence of air bubbles can be suppressed, the manufacturing process for dental prostheses can also be shortened. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a photograph of a test piece used in the evaluation of fixability and color development according to Example 1. [Figure 2] 10 is a photograph of a test piece used to evaluate fixability and color development according to Comparative Example 5. [Figure 3] As a control, this shows a fractured surface and an optical microscope photograph of the fractured surface when dental porcelain is built up on a substrate and fired using the conventional internal stain method (with fixing firing). [Figure 4] 1 is an optical microscope photograph of a fractured surface in evaluation of the interface state according to Example 1. [Figure 5] 10 is an optical microscope photograph of a fractured surface in evaluation of the interface state according to Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0018] The dental glass composition of the present invention comprises a glass powder (A) and a binder, the binder containing a hydrophilic organic compound (B) that is solid at 25°C, and is substantially free of water and propylene glycol.

[0019] <Glass powder (A)> First, the glass powder (A) contained in the glass composition of the present invention will be described. The glass powder (A) used in the present invention is not particularly limited as long as it exhibits the effects of the present invention, and any dental glass powder that can be bonded to a substrate (such as a core or frame that is a material for a dental prosthesis) can be used.

[0020] Examples of glass powder (A) include potassium aluminosilicate glass (amorphous type potassium aluminosilicate glass (4SiO2·Al2O3·K2O), leucite crystalline type potassium aluminosilicate glass), fluoroapatite glass, and lithium silicate glass. Components constituting glass powder (A) include SiO2, Al2O3, BO, Li2O, Na2O, KO, CaO, MgO, and Sb2O3, with multiple components selected in appropriate ratios depending on the substrate to be applied.

[0021] In addition, components such as TiO2, SrO, BaO, ZnO, CeO2, ZrO2, and P2O5 can also be added to the glass powder (A) in an appropriate ratio. One type of glass powder (A) may be used alone, or two or more types may be used in combination.

[0022] The coefficient of linear thermal expansion of the glass powder (A) used in the present invention is preferably close to that of the substrate to which it is applied. For example, the coefficient of linear thermal expansion in the range of 25°C to 500°C is 6.0 × 10 -6 K -1 ~14.0×10 -6 K -1 The linear thermal expansion coefficient can be measured by a known method and apparatus. For example, the linear thermal expansion coefficient can be measured by heating a sample from room temperature to 500°C using a thermal analyzer (trade name "TMA120", manufactured by Seiko Instruments Inc., heating rate 5°C / min).

[0023] The raw materials for the glass powder (A) used in the present invention can be widely used, commonly known ceramic raw materials. The reason why a wide range of ceramic raw materials can be used without limitations on the glass composition when the glass powder (A) is a glass powder is that the dental glass composition of the present invention combines powdered glass with a binder containing a hydrophilic organic compound (B), resulting in excellent fixability and adhesion at the interface between the substrate and the dental porcelain as a whole. Furthermore, the fixability and adhesion at the interface are not affected by the glass composition (presence or absence of specific oxides). Therefore, a ceramic raw material that exhibits a color development characteristic corresponding to the desired color tone can be used as the glass powder (A). There are no particular limitations on the glass powder (A) as long as it is a raw material that can be converted into the above-mentioned components by itself and / or by heating in the atmosphere. The glass composition to be obtained is calculated in advance, and the blending ratio of each raw material is determined and mixed.

[0024] The method for mixing the raw materials for the glass is not particularly limited, and known methods and devices can be used. It is preferable that the raw materials for the glass powder (A) are uniformly dispersed by mixing.

[0025] The raw materials thus mixed are melted at 1200°C or higher, the melt is cooled, and the resulting material is pulverized to produce glass powder. The method for melting the raw materials is not particularly limited, and known methods and devices can be used. The method for melting the raw materials is not particularly limited as long as all of the mixed raw materials are melted to form a uniform amorphous material and sublimation of the components does not occur.

[0026] The method for cooling the melt is not particularly limited, and known methods and devices can be used. The melt can be cooled by quenching in water, for example. The glass mass thus obtained is dried and pulverized to obtain glass powder (A). The method for pulverizing the glass mass is not particularly limited, and known methods and devices can be used. Furthermore, the method for classifying the glass mass to the desired pulverized particle size is not particularly limited, and known methods and devices can be used.

[0027] The glass powder (A) used in the present invention may contain a colorant. The colorant may be amorphous or crystalline. The form of the colorant is not particularly limited, and may be a powder. In some embodiments, the colorant may contain a crystalline powder. Examples of colorants include pigments and fluorescent agents. A single colorant may be used alone, or two or more colorants may be used in combination. The reason why the colorant contained in the glass powder (A) can be widely used without being particularly limited in terms of crystal system or type is that the dental glass composition of the present invention combines powdered glass with a binder containing a hydrophilic organic compound (B), thereby providing the composition as a whole with excellent fixability and adhesion at the interface between the substrate and dental porcelain, and the fixability and adhesion at the interface do not change depending on the type of colorant (presence or absence of a specific oxide).

[0028] The pigment is preferably an inorganic pigment. Examples of inorganic pigments include oxides of at least one element selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Y, Zr, Sn, Sb, Bi, Ce, Pr, Sm, Eu, Gd, Tb, and Er, and preferably contain an oxide of at least one element selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni, Pr, Tb, and Er. Examples of the oxides include praseodymium oxide, vanadium oxide, iron oxide, nickel oxide, chromium oxide, manganese oxide, cerium oxide, tin oxide, zirconium oxide, zinc oxide, and titanium oxide.

[0029] Furthermore, composite pigments can also be used as inorganic pigments, such as (Zr,V)O2, Fe(Fe,Cr)2O4, (Ni,Co,Fe)(Fe,Cr)2O4·ZrSiO4, and (Co,Zn)Al2O4, and preferably contain (Zr,V)O2.

[0030] Examples of fluorescent agents include Y2SiO5:Ce, Y2SiO5:Tb, (Y,Gd,Eu)BO3, Y2O3:Eu, YAG:Ce, ZnGa2O4:Zn, and BaMgAl 10 O 17 :Eu, etc.

[0031] When the glass powder (A) contains a colorant, the glass powder (A) may be obtained by simply mixing a colorant with a glass powder containing no colorant, or by mixing a colorant with a glass powder containing no colorant and fusing the mixture at 600 to 1200°C, followed by pulverizing the mixture.

[0032] The average particle size of the glass powder (A) used in the present invention is preferably 0.05 to 50 μm, more preferably 0.08 to 35 μm, even more preferably 0.1 to 20 μm, particularly preferably 0.1 to 10 μm, and most preferably 0.1 to 5 μm, in consideration of the need to balance the finest particle size possible to approximate the color tone of natural teeth with a somewhat coarse particle size for achieving color development. When the average particle size is 50 μm or less, the dental glass composition can be sufficiently adhered to the frame, does not fall off during porcelain build-up, and color particles are not visible to the naked eye, resulting in excellent aesthetics. When the average particle size is 0.05 μm or more, the composition is not burned out during firing, and sufficient color development can be achieved.

[0033] The average particle size of the glass powder (A) can be determined by a laser diffraction scattering method. The laser diffraction scattering method can be performed by volumetric measurement using, for example, a laser diffraction particle size distribution analyzer (SALD-2300, manufactured by Shimadzu Corporation). The average particle size of the glass powder (A) is the median diameter (d 50 ) means

[0034] In the dental glass composition of the present invention, the content of the glass powder (A) is preferably at a level that allows it to be kneaded with the hydrophilic organic compound (B). The content of the glass powder (A) is preferably 25% by mass or more of the total amount of the dental glass composition, and from the viewpoint of superior color development and adhesion to dental prostheses, it is more preferably 35% by mass or more, even more preferably 45% by mass or more, and particularly preferably 55% by mass or more. The content of the glass powder (A) is not particularly limited, but is preferably 97% by mass or less, more preferably 95% by mass or less, even more preferably 93% by mass or less, and particularly preferably 91% by mass or less. In an embodiment in which the binder contains a wax component (D) in addition to the hydrophilic organic compound (B), the content of the glass powder (A) is preferably 25% by mass or more of the total amount of the dental glass composition, and from the viewpoint of superior color development and adhesion to dental prostheses, more preferably 35% by mass or more, even more preferably 45% by mass or more, and particularly preferably 55% by mass or more. In the above embodiment, the content of the glass powder (A) is not particularly limited, but is preferably 95% by mass or less, more preferably 93% by mass or less, even more preferably 89% by mass or less, and particularly preferably 85% by mass or less.

[0035] In the dental glass composition of the present invention, commercially available dental porcelain may be used as the glass powder (A). The commercially available dental porcelain is not particularly limited as long as it is a dental stain porcelain, and examples of commercially available dental stain porcelain include various surface stains and internal stains such as Cerabian (registered trademark) ZR Internal Stain / External Stain and Cerabian (registered trademark) ZR Press LF Internal Stain / External Stain (manufactured by Kuraray Noritake Dental Co., Ltd.).

[0036] <Hydrophilic organic compound (B) that is solid at 25°C> Next, the hydrophilic organic compound (B) that is solid at 25° C. (hereinafter also simply referred to as "hydrophilic organic compound (B)") contained in the dental glass composition of the present invention will be described. The binder of the dental glass composition of the present invention comprises a hydrophilic organic compound (B). The bonding agent means a material having the property of being able to bond the substrate and the dental porcelain. The hydrophilic organic compound (B) is added to disperse the glass powder (A) and solidify the dental glass composition at 25°C. In addition, the inclusion of the hydrophilic organic compound (B) increases adhesion and fixation to the substrate, allowing coloring to be layered without the need for a fixation firing, and suppresses the generation of bubbles at the interface between the substrate and dental porcelain when the dental porcelain is built up and fired thereon. The hydrophilic organic compound (B) may be used alone or in combination of two or more.

[0037] The hydrophilic organic compound (B) used in the present invention preferably contains a compound that is solid at 25°C and melts when heated, in order to disperse the glass powder (A) and solidify the dental glass composition at 25°C. In this specification, "solid at 25°C" includes not only those that are solid at 25°C but also semi-solids such as ointments. A dental glass composition solidified at 25°C may be semi-solid such as ointments. The heating temperature when melting the hydrophilic organic compound (B) can be changed depending on the type of hydrophilic organic compound (B) and is not particularly limited, and may be 50°C or higher, 80°C or higher, 100°C or higher, or 150°C or higher.

[0038] In a preferred embodiment, the dental glass composition includes a glass powder (A) and a binder, the binder containing a hydrophilic organic compound (B), and the hydrophilic organic compound (B) is solid at 25°C and melts upon heating. By using a material that is solid at 25°C and melts when heated, the glass composition does not change in properties over time, such as increasing in viscosity, and furthermore, since fixing and firing are not required, the present invention has an advantage over conventional techniques in that repeated fixing and firing are not required. Therefore, the dental glass composition of the present invention can be easily layered with coloring, and porcelain (e.g., dental porcelain for surface staining) can be built up on top of that. Furthermore, the dental glass composition of the present invention can be applied in the form of a thin film.

[0039] The hydrophilic organic compound (B) refers to an organic compound having a solubility in water of 1% by mass or more at 25°C, preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and particularly preferably 30% by mass or more. Having a solubility in water of 1% by mass or more at 25°C improves adhesion and fixation to the substrate, allowing coloring to be layered without the need for a fixation firing, and suppressing the generation of bubbles when a dental porcelain is built up and fired thereon. From the above points, the hydrophilic organic compound (B) is not particularly limited and can be widely used, as long as it is solid at 25°C, can be melted by heating to a specific melting point, and is hydrophilic, as it can provide excellent dispersibility of the glass powder (A), excellent adhesion and fixation to the substrate, and suppress the generation of bubbles.

[0040] The melting point of the hydrophilic organic compound (B) is preferably 35°C or higher, more preferably 40°C or higher, even more preferably 45°C or higher, and particularly preferably 50°C or higher, from the viewpoints of achieving storage stability (maintaining a stable solid state at room temperature) and good adhesion to dental prostheses. If the melting point is lower than 35°C, the solid cannot be maintained, and there is a risk that the dental glass composition will flow off the surface when recoating or when building up a surface porcelain. Furthermore, the melting point of the hydrophilic organic compound (B) is preferably 120°C or lower, more preferably 105°C or lower, even more preferably 95°C or lower, and particularly preferably 85°C or lower. If the melting point is higher than 120°C, there is a risk that adhesion to dental prostheses will not be achieved and coloring will be insufficient.

[0041] The hydrophilic organic compound (B) is preferably a water-soluble polymer, and known compounds can be used. Examples of the water-soluble polymer include cationic water-soluble polymers, anionic water-soluble polymers, zwitterionic water-soluble polymers, and nonionic water-soluble polymers.

[0042] Examples of cationic water-soluble polymers include water-soluble polymers containing at least one selected from the group consisting of polyethyleneimine, polyallylamine, polyvinylamine, dimethylaminoethyldextran, and an imidazole group.

[0043] Examples of anionic water-soluble polymers include polysaccharides such as xanthan gum, guar gum, carrageenan, tamarind seed gum, gum arabic, locust bean gum, pectin, sodium starch glycolate, sodium starch phosphate, alginates (such as sodium alginate), propylene glycol alginate, propylene glycol alginate ester, hyaluronic acid, chondroitin sulfate, dermatan sulfate, keratan sulfate, and heparan sulfate, as well as salts thereof, as well as polyacrylic acid, polyacrylates (such as sodium polyacrylate and ammonium polyacrylate), carboxyvinyl polymers, and polymaleic acid.

[0044] Examples of the amphoteric water-soluble polymer include proteins such as gelatin, collagen, casein, and gluten, amino acids, and derivatives thereof.

[0045] Examples of nonionic water-soluble polymers include cellulose lower alkyl ether compounds such as methyl cellulose, ethyl cellulose, carboxy cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, calcium carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose; vinyl compounds such as polyvinylpyrrolidone and polyvinyl alcohol; polysaccharides and derivatives thereof such as pullulan and starch; polyacrylamides such as polyglucosyloxyethyl methacrylate; and polyalkylene glycol compounds such as polyethylene oxide, polyethylene glycol, polypropylene glycol, and block copolymers of polyethylene glycol and polypropylene glycol. In this specification, polyethylene glycol refers to a polymer having a weight-average molecular weight (Mw) of 20,000 or less. Polyethylene oxide refers to a polymer having a weight-average molecular weight (Mw) of more than 20,000, preferably 50,000 or more.

[0046] As the hydrophilic organic compound (B), a nonionic water-soluble polymer is more preferred, a polyalkylene glycol compound is even more preferred, and polyethylene glycol (PEG) is particularly preferred, because excellent color development can be achieved by improving the stability of the glass powder (A). PEG is also referred to as "macrogol" in this specification.

[0047] The weight average molecular weight (Mw) of the water-soluble polymer of the hydrophilic organic compound (B) is not particularly limited, but may be, for example, 20,000 or less. The weight average molecular weight (Mw) of the water-soluble polymer of the hydrophilic organic compound (B) is preferably 700 or more, more preferably 750 or more, even more preferably 850 or more, and particularly preferably 900 or more. The weight average molecular weight (Mw) of the water-soluble polymer of the hydrophilic organic compound (B) may be, for example, 700 or more and 20,000 or less.

[0048] In other embodiments, the weight-average molecular weight (Mw) of the water-soluble polymer of the hydrophilic organic compound (B) may be more than 20,000. The weight-average molecular weight (Mw) of the water-soluble polymer of the hydrophilic organic compound (B) may be 2.5 million or less, 1.5 million or less, 1 million or less, 300,000 or less, or 200,000 or less.

[0049] The weight average molecular weight (Mw) in this specification means the weight average molecular weight calculated as polystyrene as determined by gel permeation chromatography (GPC), and can be measured by a known method.

[0050] In another embodiment, the number average molecular weight (Mn) of the water-soluble polymer of the hydrophilic organic compound (B) is preferably 400 or more, more preferably 500 or more, and even more preferably 550 or more. The number average molecular weight (Mn) of the water-soluble polymer of the hydrophilic organic compound (B) may be 40,000 or less, 20,000 or less, or 10,000 or less.

[0051] In this specification, the number average molecular weight (Mn) means the number average molecular weight calculated based on the hydroxyl value measured in accordance with JIS K 1557-1:2007, and can be measured by a known method.

[0052] From the viewpoints of maintaining a stable solid state at room temperature and obtaining good fixation of a dental prosthesis, the content of the hydrophilic organic compound (B) used in the present invention is preferably 1 to 50 mass %, more preferably 3 to 45 mass %, even more preferably 5 to 40 mass %, and particularly preferably 7 to 35 mass %, of the total amount of the dental glass composition. Furthermore, when the binder contains the hydrophilic organic compound (B) and a wax component (D), the content of the hydrophilic organic compound (B) is preferably 1 to 40 mass %, more preferably 2.5 to 35 mass %, even more preferably 4 to 30 mass %, and particularly preferably 6 to 25 mass %, of the total amount of the dental glass composition.

[0053] The dental glass composition of the present invention is substantially free of water and propylene glycol. In this specification, unless otherwise specified, "substantially free of a certain component" means less than 10% by mass, preferably less than 1% by mass, more preferably less than 0.1% by mass (less than 1000 ppm by mass), even more preferably less than 100 ppm by mass, even more preferably 10 ppm by mass or less, particularly preferably 1 ppm by mass or less, even more particularly preferably 0.1 ppm by mass or less, and most preferably 0 ppm by mass. An example of the above embodiment is a dental glass composition in which the contents of water and propylene glycol are both less than 10% by mass.

[0054] The absence of water and propylene glycol allows the dental glass composition to have excellent stability in properties during long-term storage, and allows for easy overlay of coloring without bleeding, and allows for the deposition of porcelain thereon. Furthermore, in some cases, the generation of bubbles at the interface between the substrate and the dental porcelain during firing can be suppressed.

[0055] The dental glass composition of the present invention may, if necessary, contain other components that are liquid at 25°C (hereinafter also referred to as "other liquid components") in addition to the unsaturated fatty acid component (C) described below.

[0056] The other liquid components may be used singly or in combination of two or more. Examples of the other liquid components include organic solvents. Examples of the organic solvent include non-aromatic hydrocarbon solvents (e.g., alkanes such as pentane, hexane, heptane, octane, nonane, decane, dodecane, isododecane, and tridecane, cyclohexane, methylcyclohexane, decahydronaphthalene, and liquid paraffin); aromatic hydrocarbon solvents (e.g., benzene, toluene, xylene, diethylbenzene, mesitylene, tetralin, indene, naphthalene, and methylnaphthalene); halogenated hydrocarbon solvents (e.g., dichloromethane, dichloroethane, chloroform, Chlorobenzene); alcohol solvents (e.g., ethanol, propanol, 1-butanol, 2-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-hexanol, 2-hexanol, benzyl alcohol, 3-(benzyloxy)-1-propanol, 2-(benzyloxy)-1-butanol, 5-(benzyloxy)-1-pentanol, oleyl alcohol, and other monohydric alcohols; ethylene glycol, polyethylene glycol, polypropylene glycol, glycerin polyhydric alcohols such as; ether solvents (e.g., diethyl ether, diisopropyl ether, methyl t-butyl ether, diisoamyl ether, ethylene glycol derivatives (e.g., monoglyme (ethylene glycol dimethyl ether), methyl cellosolve, diethyl cellosolve, diglyme, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, triglyme, tetraglyme, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, ethylene glycol monobenzyl ether, ethylene glycol monophenyl ether, diethylene glycol monobenzyl ether, poly(ethylene glycol) monomethyl ether), propylene glycol derivatives (e.g., 3-hexanol propylene glycol monopropyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether), 1,1-dimethoxycyclohexane, phenetole, veratrole, dioxane, tetrahydrofuran);Ester solvents (e.g., ethyl acetate, butyl acetate, isopropyl acetate, 3-methoxy-3-methylbutyl acetate, dimethyl carbonate, diethyl malonate, ethylene carbonate, propylene carbonate, γ-butyrolactone, α-acetyl-γ-butyrolactone); ketone solvents (e.g., acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, acetophenone, propiophenone, isophorone); sulfur-containing solvents (e.g., dimethyl sulfoxide, sulfolane, diphenyl sulfide); and nitrogen-containing solvents (e.g., N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone). amide solvents such as methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone, N,N-dimethylacrylamide, N,N-dimethylacetoacetamide, N,N-diethylformamide, N,N-diethylacetamide, hexamethylphosphoramide, and methylpyrrolidone; amine solvents such as butylamine, hexylamine, octylamine, 3-methoxypropylamine, 2-methylbutylamine, and triethanolamine; nitrile solvents such as acetonitrile and benzonitrile; nitro solvents such as nitrobenzene and o-nitrotoluene; quinoline, tetrahydroquinoline, and dimethylimidazolidinone;

[0057] Some embodiments include dental glass compositions that are substantially free of water, ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, and glycerin. Another embodiment is a dental glass composition that is substantially free of water and polyhydric alcohols. In this embodiment, the absence of the specific components described above allows the dental glass composition to have excellent stability in properties during long-term storage, and allows for easy overlay of coloring without bleeding, allowing for porcelain buildup thereon. Furthermore, in some cases, the generation of bubbles at the interface between the substrate and the dental porcelain during firing can be suppressed.

[0058] Another embodiment is a dental glass composition that is substantially free of water and alcohol compounds. In this embodiment, the absence of water and alcohol compounds allows the dental glass composition to have excellent stability in properties during long-term storage, and allows for easy overlay of coloring without bleeding, allowing for porcelain buildup thereon. Furthermore, the generation of bubbles at the interface between the substrate and the dental porcelain during firing can be suppressed. The content of the alcohol compound is preferably less than 10% by mass, more preferably 8% by mass or less, even more preferably 5% by mass or less, particularly preferably 3% by mass or less, and most preferably 1% by mass or less. In the above embodiment, the content of the alcohol compound may be less than 0.1% by mass, less than 100 ppm by mass, 10 ppm by mass or less, 1 ppm by mass or less, 0.1 ppm by mass or less, or 0 ppm by mass.

[0059] In another embodiment, a dental glass composition substantially free of an amine compound can be used. By substantially free of an amine compound, the dental glass composition can achieve excellent stability in properties during long-term storage, and can easily be overlaid with coloring without bleeding, allowing for the deposition of porcelain on top of the coloring. Furthermore, the generation of bubbles at the interface between the substrate and the dental porcelain during firing can be suppressed. The content of the amine compound is preferably less than 10% by mass, more preferably 8% by mass or less, even more preferably 5% by mass or less, particularly preferably 3% by mass or less, and most preferably 1% by mass or less. In the above embodiment, the content of the amine compound may be less than 0.1% by mass, less than 100 ppm by mass, 10 ppm by mass or less, 1 ppm by mass or less, 0.1 ppm by mass or less, or 0 ppm by mass.

[0060] In the embodiment that does not contain water, an alcohol compound, or an amine compound, the absence of water and a polyhydric alcohol allows the dental glass composition to have excellent stability in properties during long-term storage, and allows for easy overlay of coloring without bleeding, and allows for porcelain build-up thereon.Furthermore, in some cases, the generation of bubbles at the interface between the substrate and the dental porcelain during firing can be suppressed.

[0061] Furthermore, another embodiment includes a dental glass composition that is substantially free of other components that are liquid at 25°C other than the unsaturated fatty acid component (C). "Substantially free of a component" is as explained above. For example, the embodiment includes a dental glass composition in which the content of components that are liquid at 25°C other than the unsaturated fatty acid component (C) is less than 1 mass%.

[0062] <Unsaturated fatty acid component (C)> In the dental glass composition of the present invention, the binder preferably further contains an unsaturated fatty acid component (C). Examples of the unsaturated fatty acid component (C) include unsaturated fatty acids (C-1) and unsaturated fatty acid esters (C-2). As the unsaturated fatty acid component (C), one type may be used alone, or two or more types may be used in combination.

[0063] The unsaturated fatty acid component (C) is liquid at 25°C. When the dental glass composition of the present invention further contains the unsaturated fatty acid component (C), the smoothness of the composition can be increased, improving operability. In addition, the unsaturated fatty acid component (C) can suppress the hygroscopicity of the dental glass composition, thereby achieving excellent property stability during long-term storage. There are no particular limitations on the unsaturated fatty acid component (C), and desired effects such as the ability to adjust the viscosity of the hydrophilic organic compound (B) in a molten state can be achieved.

[0064] Known unsaturated fatty acids (C-1) can be used, including monounsaturated fatty acids such as crotonic acid, myristoleic acid, palmitoleic acid, sapienic acid, elaidic acid, vaccenic acid, paulic acid, oleic acid, gadoleic acid, eicosenoic acid, erucic acid, and nervonic acid; and polyunsaturated fatty acids such as linoleic acid, conjugated linoleic acid, γ-linolenic acid, eicosadienoic acid, dihomo-γ-linolenic acid, arachidonic acid, α-linolenic acid, pinolenic acid, stearidonic acid, α-eleostearic acid, β-eleostearic acid, mead acid, adrenic acid, eicosatrienoic acid, eicosapentaenoic acid, docosapentaenoic acid, docosahexaenoic acid, tetracosapentaenoic acid, tetracosahexaenoic acid, bosseopentaenoic acid, osbondo acid, sardine acid, and herring acid. As the unsaturated fatty acid (C-1), from the viewpoint of suppressing the moisture absorption of the dental glass composition, unsaturated fatty acids having 8 to 30 carbon atoms are preferred, unsaturated fatty acids having 10 to 25 carbon atoms are more preferred, unsaturated fatty acids having 12 to 20 carbon atoms are even more preferred, and polyunsaturated fatty acids having 12 to 20 carbon atoms are particularly preferred. In this specification, "polyunsaturated" is not particularly limited as long as the degree of unsaturation (number of carbon-carbon double bonds) is 2 or more.

[0065] Examples of the unsaturated fatty acid ester (C-2) include esters of the above-mentioned unsaturated fatty acids and mixtures thereof. From the viewpoint of suppressing the moisture absorption of the dental glass composition, the unsaturated fatty acid ester (C-2) is preferably an unsaturated fatty acid ester having 8 to 30 carbon atoms, more preferably an unsaturated fatty acid ester having 10 to 25 carbon atoms, even more preferably an unsaturated fatty acid ester having 12 to 20 carbon atoms, and particularly preferably a polyunsaturated fatty acid ester having 12 to 20 carbon atoms.

[0066] The unsaturated fatty acid component (C) is compatible with or dissolves in the hydrophilic organic compound (B) in a molten state, thereby easily improving the dispersibility of the glass powder (A) and the hydrophilic organic compound (B). The inclusion of the unsaturated fatty acid component (C) allows for the adjustment of the viscosity of the hydrophilic organic compound (B) in a molten state, enhancing the dispersibility of the glass powder (A), allowing for easy and uniform coloring, and providing superior lubricity during drawing. Furthermore, the inclusion of the unsaturated fatty acid component (C) enhances the dispersibility of the glass powder (A) and the hydrophilic organic compound (B), thereby enhancing the fixation of the dental glass composition in combination with the components of the binder, including the hydrophilic organic compound (B), and also providing excellent color development. Among the unsaturated fatty acid components (C), the unsaturated fatty acid (C-1) is preferred due to its excellent effects.

[0067] The unsaturated fatty acid component (C) in the present invention must burn out sufficiently so as not to affect the color tone after firing when the dental glass composition is applied to a substrate, and then a dental porcelain is formed thereon, and then fired. Therefore, the boiling point of the unsaturated fatty acid component (C) is preferably 400°C or lower, more preferably 385°C or lower, and even more preferably 370°C or lower. Furthermore, if an unsaturated fatty acid component (C) with a boiling point of less than 100°C is used, it may volatilize and dry even at room temperature, making it difficult to maintain a stable solid state. Therefore, the boiling point of the unsaturated fatty acid component (C) is preferably 100 to 400°C, more preferably 100 to 385°C, and even more preferably 100 to 370°C.

[0068] When the binder contains an unsaturated fatty acid component (C), the content of the unsaturated fatty acid component (C) is preferably 0.5 to 30 mass %, more preferably 1.0 to 25 mass %, even more preferably 1.5 to 20 mass %, and particularly preferably 2.0 to 18 mass %, of the total amount of the dental glass composition. When the content of the unsaturated fatty acid component (C) is within this range, it is easy to impart to a dental prosthesis that can obtain appropriate strength and heat resistance, it is easy to improve the sliding property and fixation property of the dental glass composition when drawing, and it also has excellent color development. When the binder contains a wax component (D) in addition to the hydrophilic organic compound (B) and the unsaturated fatty acid component (C), the content of the unsaturated fatty acid component (C) is preferably 0.2 to 30 mass %, more preferably 0.5 to 25 mass %, even more preferably 1.0 to 20 mass %, and particularly preferably 1.5 to 18 mass %, of the total amount of the dental glass composition.

[0069] Furthermore, when the binder of the present invention contains an unsaturated fatty acid component (C), whether the binder contains or does not contain a wax component (D) in addition to the hydrophilic organic compound (B), the content of the unsaturated fatty acid component (C) is preferably equal to or less than the content of the hydrophilic organic compound (B), and more preferably less than the content of the hydrophilic organic compound (B).

[0070] A preferred embodiment includes a dental glass composition in which the binder comprises a hydrophilic organic compound (B) that is solid at 25°C and an unsaturated fatty acid component (C) that is liquid at 25°C.

[0071] <Wax component (D)> The dental glass composition of the present invention preferably further contains a wax component (D) in which the binder is solid at 25°C. By including the wax component (D), the wax component (D) and the binder other than the wax component (D) work together to promote the solidification of the dental glass composition at room temperature, and furthermore, the hygroscopicity of the dental glass composition can be suppressed, resulting in excellent property stability during long-term storage. The wax component (D) may be used alone or in combination of two or more types. The wax component (D) has a solubility in water at 25°C of less than 1% by mass.

[0072] The melting point of the wax component (D) used in the present invention is preferably 35 to 120°C, more preferably 40 to 110°C, and even more preferably 50 to 100°C, from the viewpoint of obtaining excellent property stability during long-term storage at room temperature and good adhesion of dental prostheses. If the melting point is 35°C or lower, the wax component (D) cannot maintain its solid state, and there is a risk that the dental glass composition will flow out from the surface when recoating or when building up a surface porcelain. On the other hand, if the melting point is higher than 120°C, there is a risk that adhesion to the dental prosthesis will not be obtained and coloring will be insufficient.

[0073] The content of the wax component (D) is preferably 1 to 55 mass %, more preferably 3 to 50 mass %, even more preferably 5 to 45 mass %, and particularly preferably 7 to 35 mass %, of the total amount of the dental glass composition of the present invention. When the content of the wax component is within this range, it is easy to obtain a solid dental glass composition that, in combination with other binders, has excellent color development or colorability, high moldability and strength, and good adhesion and fixation to dental prostheses.

[0074] In one embodiment, the binder of the dental glass composition of the present invention preferably contains a wax component having a melting point of less than 75°C (hereinafter, sometimes referred to as "first wax (D-1)"). When the dental glass composition contains the first wax (D-1), the dental glass composition has better sliding properties during drawing. In particular, when the dental glass composition does not contain the unsaturated fatty acid component (C), the dental glass composition has better sliding properties during drawing when it contains the first wax (D-1).

[0075] The melting point of the first wax (D-1) is preferably 50°C or higher and lower than 75°C, more preferably 55 to 73°C, and even more preferably 60 to 70°C. Preferred examples of the first wax (D-1) include white petrolatum (melting point: approximately 38 to 60°C), stearic acid (melting point: approximately 69 to 70°C), candelilla wax (melting point: approximately 68 to 72°C), beeswax (melting point: approximately 63°C), hardened palm oil (melting point: approximately 59°C), microcrystalline wax (melting point: approximately 67 to 70°C), paraffin wax (melting point: approximately 47 to 69°C), hardened beef tallow oil (melting point: approximately 46°C), and ketone wax (melting point: approximately 60 to less than 75°C).

[0076] In one embodiment, the content of the first wax (D-1) is preferably 1 to 55 mass %, more preferably 1.5 to 50 mass %, even more preferably 5 to 45 mass %, and particularly preferably 7 to 35 mass %, based on the total amount of the dental glass composition. By keeping the content within this range, a dental glass composition having excellent property stability during long-term storage at room temperature and excellent smoothness during drawing can be obtained.

[0077] When the dental glass composition of the present invention contains the unsaturated fatty acid component (C) and / or the first wax (D-1), smoothness and sliding properties during drawing are improved, but the dental glass composition adhering to the dental prosthesis may be easily removed by rubbing, etc. From the viewpoint of improving the adhesion of the dental glass composition, it is preferable to contain a high-melting point wax (D-2) (hereinafter sometimes referred to as "second wax (D-2)") together with the unsaturated fatty acid component (C) and / or the first wax (D-1).

[0078] In this specification, the second wax (D-2) has a melting point of 75 to 120° C. When the second wax (D-2) has a melting point of 75° C. or higher, it can conform to the fine irregularities on the surface of the substrate when combined with the unsaturated fatty acid component (C) and / or the first wax (D-1), thereby improving the fixation of the dental glass composition. Examples of the second wax (D-2) include carnauba wax, hardened castor oil (melting point: approximately 80 to 90°C), polyolefin wax (having a melting point of 75°C or higher, such as low-molecular-weight polyethylene wax (melting point: approximately 100 to 120°C)), long-chain saturated fatty acids (behenic acid, etc.), saturated fatty acid amides (stearic acid amide (melting point: approximately 98 to 105°C)), and microcrystalline wax (having a melting point of approximately 75 to 98°C). Behenic acid and carnauba wax are preferred because they have a high melting point, can be solidified with a small amount, and do not leave behind any burned residue after combustion.

[0079] The content of the second wax (D-2) in the wax component (D) is preferably 3 to 55 mass%, more preferably 5 to 50 mass%, even more preferably 10 to 45 mass%, and particularly preferably 15 to 35 mass%. When the content of the second wax (D-2) is within this range, it is easy to achieve a balance between the smoothness of the dental glass composition when drawing and the fixation of the dental glass composition. In one embodiment, the content of the second wax (D-2) is preferably less than the content of the first wax (D-1).

[0080] Furthermore, in a dental glass composition containing the second wax (D-2), the content of the second wax (D-2) is preferably less than 15 mass %, more preferably less than 12 mass %, and even more preferably less than 10 mass %, of the total amount of the dental glass composition, in order to improve the smoothness of the dental glass composition when drawing and the adhesion of the dental glass composition.

[0081] The wax component (D) in the present invention must burn out sufficiently so as not to affect the color tone after firing when the dental glass composition is applied to a substrate, and then a dental porcelain is built up thereon, and then fired. Therefore, the boiling point of the wax component (D) is preferably 400°C or lower, more preferably 385°C or lower, and even more preferably 370°C or lower.

[0082] A preferred embodiment includes a dental glass composition in which the binder comprises a hydrophilic organic compound (B) that is solid at 25°C, an unsaturated fatty acid component (C) that is liquid at 25°C, and a wax component (D).

[0083] Another preferred embodiment includes a dental glass composition, wherein the binder comprises a hydrophilic organic compound (B) that is solid at 25°C, and a wax component (D).

[0084] Another preferred embodiment is a dental glass composition in which the binder consists solely of a hydrophilic organic compound (B) that is solid at 25°C.

[0085] Another preferred embodiment includes a dental glass composition in which the binder consists solely of a hydrophilic organic compound (B) that is solid at 25°C and an unsaturated fatty acid component (C) that is liquid at 25°C.

[0086] Another preferred embodiment is a dental glass composition in which the binder consists only of a hydrophilic organic compound (B) that is solid at 25°C and a wax component (D).

[0087] One preferred embodiment is a dental glass composition in which the binder consists only of a hydrophilic organic compound (B) that is solid at 25°C, an unsaturated fatty acid component (C) that is liquid at 25°C, and a wax component (D).

[0088] In another preferred embodiment, the total content of the glass powder (A) and the binder is preferably 90% by mass or more of the total amount of the dental glass composition, and from the viewpoint of superior color development and adhesion to dental prostheses, is more preferably 95% by mass or more, even more preferably 97% by mass or more, and particularly preferably 98% by mass or more.

[0089] The dental glass composition of the present invention may contain, if necessary, known additives used in dental glass compositions. Examples of such additives include resins (e.g., ethylene-vinyl acetate copolymers), binders, antioxidants, surfactants, preservatives, fungicides, and antibacterial agents. The additives may be used alone or in combination of two or more.

[0090] The dental glass composition of the present invention may optionally contain an adhesive resin (a known adhesive resin, for example, a petroleum resin such as rosin and / or a rosin-modified product). Examples of the rosin-modified product include esters such as rosin ester, hydrogenated rosin ester, and / or polymerized rosin ester.

[0091] The dental glass composition of the present invention can be produced by a known method using a glass powder (A) and a hydrophilic organic compound (B). Furthermore, when the dental glass composition contains an unsaturated fatty acid component (C) and a wax component (D), it can also be produced by a known method. The production method is not particularly limited, but the dental glass composition of the present invention can be obtained, for example, by adding glass powder (A) to the hydrophilic organic compound (B), the unsaturated fatty acid component (C), and the wax component (D), kneading them, and extruding the mixture.

[0092] In one embodiment, when the binder component (particularly the hydrophilic organic compound (B) and the wax component (D)) has a high melting point, the dental glass composition of the present invention can also be obtained by a method of manufacturing the dental glass composition, in which the binder component is heated to melt, while the glass powder (A) is added and mixed, the mixture is poured into a mold, and solidified by cooling while blowing air, and then the mixture is removed from the mold. The dental glass composition of the present invention can be obtained by adding the glass powder (A) to the molten binder component, mixing, dispersing, and then cooling.

[0093] The components can be mixed while the components other than the glass powder (A) (preferably the binder component) are in a liquid state. Usually, a binder component with a melting point higher than room temperature is heated to a temperature equal to or higher than its melting point to become liquid, and then the components are mixed. The heating temperature for melting the binder component can be varied depending on the type of binder component, and is not particularly limited, and may be 50°C or higher, 80°C or higher, 100°C or higher, or 150°C or higher.

[0094] The order in which the components are mixed is not particularly limited, but it is preferable to add and disperse the glass powder (A) in the liquid hydrophilic organic compound (B). When the unsaturated fatty acid component (C) is included, the glass powder (A) may be dispersed in the hydrophilic organic compound (B) and then mixed with the unsaturated fatty acid component (C). However, it is preferable to premix the hydrophilic organic compound (B) and the unsaturated fatty acid component (C) and then add the glass powder (A). Alternatively, a portion of the hydrophilic organic compound (B) and a portion of the unsaturated fatty acid component (C) may be premixed, the glass powder (A) may be added, and further mixed, and then the hydrophilic organic compound (B) and the unsaturated fatty acid component (C) may be added. A solid dental glass composition can be obtained by cooling the mixture containing the components in a mold at a temperature lower than the melting point of the hydrophilic organic compound (B).

[0095] The dental glass composition of the present invention contains a glass powder (A) and a hydrophilic organic compound (B) that is solid at 25°C, and may further contain other components (optional components) as long as they do not impede the effects of the present invention, as long as they are substantially free of solvents.

[0096] Such other components include colorants, pH adjusters, polymerization accelerators, polymerization initiators, etc. Examples of colorants include colorants that are decolorized during baking.

[0097] Coloring agents that are decolorized during baking include food dyes that dissolve in organic solvents. Examples of food dyes include organic dyes containing two or more aromatic groups, such as Yellow No. 4 (tartrazine), Yellow No. 5 (Sunset Yellow FCF), Red No. 2 (amaranth), Red No. 102 (New Coccine), Blue No. 1 (Brilliant Blue FCF), Blue No. 2 (indigo carmine), and Green No. 3 (Fast Green FCF); organic dyes containing condensed aromatic groups with a xanthene nucleus (xanthene dyes), such as Acid Red 289, Bromopyrogallol Red, Rhodamine B, Rhodamine 6G, Rhodamine 6GP, Rhodamine 3GO, Rhodamine 123, Eosin, Eosin B, Eosin Y, Fluorescein, and Fluorescein Isothiocyanate; cochineal dye (carminic acid dye); and betalain dyes, such as beet red (main components: isobetanin and betanin), betanin, isobetanin, probetanin, and neobetanin.

[0098] In one embodiment, a dental glass composition is provided that contains a glass powder (A), a hydrophilic organic compound (B), and, optionally, an unsaturated fatty acid component (C), and is substantially free of colorants that decolorize upon firing. "Substantially free of colorants that decolorize upon firing" refers to the content of colorants that decolorize upon firing being, for example, 1,000 ppm by mass or less, preferably 100 ppm by mass or less, more preferably 10 ppm by mass or less, even more preferably 1 ppm by mass or less, particularly preferably 0.1 ppm by mass or less, and most preferably 0 ppm by mass, relative to the mass of the dental glass composition. The content of other components is not particularly limited, but is preferably 15.0% by mass or less, more preferably 12.0% by mass or less.

[0099] The method for producing a dental prosthesis of the present invention includes a step of applying the dental glass composition to a substrate of a dental prosthesis having a ceramic surface, and a step of firing the substrate after the dental glass composition has been applied but before the dental porcelain has been built up, without firing the substrate. The substrate is as described above. The substrate of a dental prosthesis having a ceramic surface refers to the substrate (core, frame, etc.) before the dental porcelain has been built up. The method for producing a dental prosthesis of the present invention includes a step of applying the dental glass composition to a substrate of a dental prosthesis having a ceramic surface, and a step of firing the substrate to which the dental glass composition has been applied without firing the substrate, after which dental porcelain is built up. The substrate is as described above. The substrate of a dental prosthesis having a ceramic surface refers to the substrate (core, frame, etc.) before dental porcelain is built up.

[0100] The substrate for a dental prosthesis is not particularly limited as long as it is used for dental purposes, and examples thereof include various ceramics (dental ceramics such as zirconium oxide (zirconia), aluminum oxide (alumina), feldspar glass, and lithium disilicate); and ceramics such as metal-ceramic dental prostheses and all-ceramic dental prostheses, which are formed by baking a single layer or multiple layers of dental porcelain that expresses the color tone of ivory or enamel onto a dental metal core or the above-mentioned ceramic core.

[0101] The substrate of the dental prosthesis may contain ceramics at least in part and have a ceramic surface, and may be entirely made of ceramics. A substrate for a dental prosthesis having a ceramic surface can be manufactured, for example, by processing a commercially available product (e.g., Katana (registered trademark) Zirconia STML (manufactured by Kuraray Noritake Dental Co., Ltd.)) into a dental prosthesis having the desired shape using a known method.

[0102] The method for applying the dental glass composition to the substrate of a dental prosthesis having a ceramic surface is not particularly limited, and known methods, devices and instruments can be used.

[0103] The dental glass composition of the present invention can be applied directly to a substrate of a dental prosthesis having a ceramic surface as a porcelain stain for internal staining and surface staining, followed by firing to color the substrate. Furthermore, when the substrate of a dental prosthesis having a ceramic surface is made of zirconia, which has become popular recently and is highly transparent, the glass composition of the present invention can be applied directly to the zirconia as a porcelain stain for internal staining, followed by firing to color the zirconia frame itself, for example, to resemble ivory. In this specification, "direct application" means application in its original state without going through a process of forming a paste by adding a special liquid (a liquid material containing water, ethanol, etc.).

[0104] In another aspect, the present invention provides use of a dental glass composition comprising a glass powder (A), a hydrophilic organic compound (B) that is solid at 25°C, an unsaturated fatty acid component (C), and a wax component (D), and which is substantially free of water and propylene glycol, as a "direct application" type porcelain stain.

[0105] The dental glass composition of the present invention may be solid at 25° C. Even if the dental glass composition of the present invention is solid at room temperature, it can be used as a “direct application” porcelain stain. In this specification, "room temperature" is within the range of 20°C ± 15°C as specified in JIS Z 8703-1983, and may be, for example, 25°C.

[0106] The dental glass composition of the present invention can easily imitate tooth features (hereinafter, sometimes referred to as "characters") on a ceramic-surfaced dental prosthesis substrate. Specifically, the dental glass composition of the present invention can be used alone like drawing charcoal or crayons. Furthermore, by sharpening the tip of the composition into a pencil, fine details such as enamel cracks and hairlines can be easily imprinted. Furthermore, the composition can be applied to a variety of techniques, such as applying it to a blush brush or a sponge-like eyeshadow tip and rubbing it onto a ceramic-surfaced dental prosthesis substrate, enabling color shading (gradation and shading). Examples of characters include the white band of natural teeth, staining or discoloration of the cervical or approximal surfaces, demineralization, enamel cracks, and hairlines where coloring components have penetrated.

[0107] With conventional porcelain stains, a fixing firing is performed after the porcelain stain is applied. Specifically, when using conventional porcelain stains, a fixing firing is always performed after the porcelain stain is applied and before the porcelain is built up on the surface to prevent the porcelain stain from bleeding or running out. In addition, to imitate the internal structure of natural teeth, such as dentin, the dental prosthesis is stained vertically from the incisal edge to the cervical area, and to express white bands, etc., the porcelain stain must be applied horizontally mesiodistally. Each time the staining direction is changed, a fixing firing is required to prevent the stains from mixing.

[0108] On the other hand, the dental glass composition of the present invention is a solid with no fluidity, unlike conventional porcelain stains, and therefore has excellent adhesion to the drawn dental glass composition, eliminating the need for fixing firing after each recoat. Furthermore, even when dental porcelain is built up on the surface without fixing and firing after application of the dental glass composition of the present invention, the dental glass composition has excellent adhesion to the final dental prosthesis, preventing bleeding and flowing, and furthermore, the subsequent firing of the built-up dental porcelain does not cause peeling, foaming, or blackening at the interface between the porcelain and the substrate, making it possible to omit the fixing and firing step. Therefore, in the method for manufacturing a dental prosthesis of the present invention, a dental prosthesis can be obtained by applying the dental glass composition to the substrate, building up the dental porcelain, and then firing it once, thereby simplifying the manufacturing process and significantly improving manufacturing efficiency.

[0109] After applying the dental glass composition of the present invention, in the case of the internal staining method, dental porcelain is built up and fired, and then the outer shape is adjusted to match the natural tooth to represent the shape of a dental crown. Then, a glazing (self-glazing) step is carried out in which only the surface layer of dental porcelain is melted to obtain a gloss, thereby completing the dental prosthesis. The dental glass composition of the present invention can also be used in a surface staining method in which, after shaping into the final outer shape, glazing is performed using a glaze glass having a low melting temperature to impart luster and simultaneously coloring.

[0110] The dental porcelain used in the method for producing a dental prosthesis of the present invention is not particularly limited, and any known dental porcelain can be used. Known dental porcelains that can be used include commercially available products (for example, Cerabian (registered trademark) ZR Internal Stain / External Stain, Cerabian (registered trademark) ZR Press LF Internal Stain / External Stain (manufactured by Kuraray Noritake Dental Co., Ltd.)).

[0111] The firing temperature (maximum firing temperature) in the firing step after laying down the dental porcelain in the present invention can be appropriately changed depending on the type of dental porcelain, the form of use, etc., and is not particularly limited as long as it allows the colorant (e.g., inorganic pigment) to develop color, but is preferably 700°C or higher, more preferably 730°C or higher, and even more preferably 750°C or higher. The upper limit of the firing temperature is not particularly limited, but is preferably 1100°C or lower, more preferably 1050°C or lower, and even more preferably 1000°C or lower. The temperature rise rate during firing up to the maximum firing temperature can be appropriately changed depending on the type of porcelain, and is not particularly limited, but is preferably about 10 to 70°C / min, and more preferably about 20 to 60°C / min.

[0112] Examples of dental prostheses finally obtained using the glass composition of the present invention include metal ceramic dental prostheses and all-ceramic dental prostheses restored using an alumina core, zirconia core, or the like.

[0113] Specific examples of the dental prosthesis that can be finally obtained include copings, frameworks, denture bases, dentures, orthodontic products, and implant products.

[0114] Examples of dentures include crowns, bridges, inlays, onlays, and laminate veneers.

[0115] Orthodontic products include, for example, brackets.

[0116] Examples of dental implant products include implants, abutments, implant fixtures, implant bridges, implant bars, and implant superstructures that are prosthetics with attached gum (gingival) parts. [Example]

[0117] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0118] The solid dental glass compositions of Examples 1 to 14 and Comparative Examples 1 to 9 were prepared as follows, and their properties were evaluated. The results are shown in Tables 1 and 2. In addition, for each component in Tables 1 and 2, "%" represents mass %. In addition, in Tables 1 and 2, "PEG-2000" and "PEG-1000" refer to polyethylene glycol with a weight-average molecular weight (Mw) of 2000 and polyethylene glycol with a weight-average molecular weight (Mw) of 1000, respectively. In addition, in Tables 1 and 2, "macrogol ointment" means a mixture of equal amounts of polyethylene glycol 400 (Mw: 400) and 4000 (Mw: 4000). In Tables 1 and 2, "room temperature" refers to evaluation at 25°C. The properties of the composition were also evaluated at 25°C.

[0119] The weight average molecular weight was calculated in terms of polystyrene as determined by gel permeation chromatography (GPC).

[0120] The solubility of PEG-2000 in water at 25°C was 50% by mass or more. The solubility of PEG-1000 in water at 25°C was 50% by mass or more. The solubility of macrogol ointment in water at 25°C was 50% by mass or more. The solubilities of stearic acid, white petrolatum, carnauba wax, and behenic acid in water at 25°C were all less than 1% by mass.

[0121] [Examples 1 to 14 and Comparative Examples 1 to 6 and 9] The hydrophilic organic compound (B), unsaturated fatty acid component (C), and wax component (D) were melted in a container on a hot stirrer at 120°C to the mass percentages listed in Tables 1 and 2. Glass powder (A) (Cerabian® ZR Internal Stain, manufactured by Kuraray Noritake Dental Co., Ltd.) was then added and mixed with a metal spatula until uniform. The resulting mixture was poured into a mold measuring 20.0 mm in length, 3.0 mm in width, and 3.0 mm in depth, and cooled to solidify, producing a solid dental glass composition. The glass powder (A) product was a potassium aluminosilicate glass containing pigment and having a reddish-brown color.

[0122] The average particle diameter of the glass powder (A) was determined by a laser diffraction particle size distribution analyzer (SALD-2300, manufactured by Shimadzu Corporation) as the median diameter (d 50 ) was taken as the average particle size.

[0123] [Comparative Examples 7 and 8] Each component shown in Table 2 was weighed on a glass plate so as to give the mass % shown in Table 2, and mixed as is with a spatula to obtain a paste composition.

[0124] [Preparation of zirconia sintered body] Commercially available dental zirconia (Katana (registered trademark) Zirconia STML: manufactured by Kuraray Noritake Dental Co., Ltd.) was processed into a cylindrical shape with a diameter of approximately 18 mm, and fired in a firing furnace "Noritake Katana (registered trademark) F-1" manufactured by SK Medical Electronics Co., Ltd. at a maximum temperature of 1550°C for 2 hours, thereby obtaining a zirconia sintered body to be used as a substrate.

[0125] [Method for evaluating fixation] A line was drawn on the surface of the zirconia sintered body of the base material prepared by the above-mentioned method using the dental glass composition of each Example and Comparative Example prepared by the above-mentioned method, and dental porcelain (Cerabian (registered trademark) ZR Translucent Tx: manufactured by Kuraray Noritake Dental Co., Ltd.) mixed with purified water was built up on top of the line.

[0126] <Evaluation criteria> For all the dental glass compositions obtained, if the shape of the drawn lines was maintained, it was evaluated as "a", if even one of the drawn lines maintained its shape but the colors were mixed, it was evaluated as "b", and if even one of the lines flowed together with the porcelain and the shape of the line was not maintained, it was evaluated as "c" (n=3). For practical use, "a" and "b" were considered to be acceptable products.

[0127] [Color development evaluation method] A line was drawn on the surface of the zirconia sintered body of the base material prepared by the above-mentioned method using the dental glass composition of each Example and Comparative Example prepared by the above-mentioned method, and a dental porcelain (Cerabian (registered trademark) ZR Translucent Tx: manufactured by Kuraray Noritake Dental Co., Ltd.) mixed with purified water was layered on top of the line, and fired by holding at 930°C for 1 minute.

[0128] <Evaluation criteria> In visual observation of all the obtained dental glass compositions, if the color of the drawn lines was clear, it was evaluated as "a", if even one was unclear and whitish, it was evaluated as "b", and if even one color was bleeding or no color was observed, it was evaluated as "c" (n=3). In practical use, "a" and "b" were considered to be acceptable products.

[0129] A photograph of the test piece used to evaluate the fixability and color development of Example 1 is shown in Figure 1, and a photograph of the test piece used to evaluate the fixability and color development of Comparative Example 5 is shown in Figure 2. As shown in the photograph in Figure 2, in Comparative Example 5, the shape of the drawn line could not be maintained and the color was blurred. In contrast, in Figure 1, the shape of the drawn line was maintained and the color of the drawn line was clear.

[0130] [Method for evaluating the interface state] The sample evaluated in the above [Method for evaluating color development] was cut in a direction perpendicular to the drawn line, and the cut surface was polished to a smooth state. The polished fractured surfaces were observed under an optical microscope (DIGITAL MICROSCOPE KH-7700: Hirox Co., Ltd.) at 1000x magnification to check for significant bubbles or peeling in the dental glass composition at the interface between the substrate and the dental porcelain. As a control, dental porcelain was built up on a substrate using the conventional internal stain method (with fixing firing) and fired. When the fractured surface was observed, fine bubbles were found. Figure 3 shows the fractured surface for the evaluation method and the results (photographs) of the control fractured surface observed under an optical microscope. If there are only fine bubbles, as in Figure 3, this does not mean that peeling will occur. Therefore, the interface was evaluated (n=3) using the following evaluation criteria.

[0131] <Evaluation criteria> If all samples have the same amount of bubbles as the control: "a" If even one sample is found to have more bubbles than the control: "b" If even one sample has significantly more bubbles than the control, or if interfacial delamination is observed in even one location: "c" If interfacial delamination is observed in several places on even one sample: "d" In practical use, "a" and "b" were deemed to be acceptable products.

[0132] An optical microscope photograph of the fractured surface in the evaluation of the interface state in Example 1 is shown in Fig. 4. An optical microscope photograph of the fractured surface in the evaluation of the interface state in Comparative Example 2 is shown in Fig. 5. In Fig. 5, an air layer was formed between the substrate and the porcelain, and clear delamination was confirmed.

[0133] [Method for evaluating operability] A line was drawn on the surface of the zirconia sintered body prepared in the above [Preparation of zirconia sintered body] using the dental glass composition prepared by the above method.

[0134] <Evaluation criteria> For all samples, if a line could be drawn and spread evenly, it was rated as "a", if even one line could be drawn but was not uniform in parts, it was rated as "b", and if even one surface of the zirconia sintered body was exposed, it was rated as "c" (n=3). For practical use, "a" and "b" were considered to be acceptable products.

[0135] [Table 1]

[0136] [Table 2]

[0137] In Comparative Examples 1 to 4, which did not contain the hydrophilic organic compound (B), the observation of the cut surface revealed the presence of peeling, cavities, or bubbles at part of the interface between the base material (substrate) and the porcelain. It is presumed that the stain solidified only with the wax component was in a water-repellent (non-wettable) state with the porcelain used for building up, and that an air layer remained at the interface between the base material and the porcelain upon firing the porcelain, resulting in the peeling, cavities, or bubbles.

[0138] In Comparative Examples 5 to 9, which were in a paste form, none of the resins were fixed or developed color unless they were baked for fixation, which resulted in a loss of aesthetic appeal as a dental prosthesis. Paste-like compositions essentially require a fixing firing process, and when ceramic is built up after the paste-like composition has been applied, some of the composition may have mixed with the ceramic, causing the paste-like composition to shift from the original application location, thereby impairing aesthetics.

[0139] On the other hand, Examples 1 to 14, which are dental glass compositions containing a hydrophilic organic compound (B), exhibited good fixability and color development even without performing a fixing bake. In particular, comparisons between Example 5 and Comparative Example 1 and between Example 12 and Comparative Example 3 confirmed that the present invention exhibits excellent effects.

[0140] Furthermore, it was also confirmed that the dental glass compositions of Examples 1 to 14 did not change over time, were excellent in operability, and could be applied uniformly. [Industrial Applicability]

[0141] The glass composition of the present invention is solidified to have good adhesion to dental prostheses, so that the glass composition itself undergoes almost no change over time, can be applied as a thin film to dental prostheses, and, because it has no fluidity, can be applied without bleeding. It is easy to operate and allows dental prostheses having a desired color tone to be easily produced, and therefore, can be suitably used as a dental glass composition. Furthermore, as the demand for ceramic dental crowns continues to grow and individual aesthetic requirements become more stringent, it is expected that dental glass compositions will be used more frequently. Therefore, the dental glass composition of the present invention, which does not require fixing or firing, is useful.

Claims

1. A glass powder (A) and a binder, the binder contains a hydrophilic organic compound (B) that is solid at 25°C, the hydrophilic organic compound (B) that is solid at 25°C is a polyalkylene glycol compound, The water content is less than 0.1% by mass, The propylene glycol content is less than 0.1% by mass, and A dental glass composition that is a porcelain stain.

2. 2. The dental glass composition according to claim 1, wherein the average particle size of the glass powder (A) is 0.05 μm to 50 μm.

3. 2. The dental glass composition according to claim 1, wherein the hydrophilic organic compound (B) has a melting point of 35[deg.] C. or higher.

4. 2. The dental glass composition of claim 1, wherein the polyalkylene glycol compound is polyethylene glycol.

5. 2. The dental glass composition according to claim 1, wherein the content of the hydrophilic organic compound (B) is 1 to 50% by mass.

6. 2. The dental glass composition of claim 1, wherein the binder further comprises an unsaturated fatty acid component (C) that is liquid at 25°C.

7. 7. The dental glass composition according to claim 6, wherein the content of the unsaturated fatty acid component (C) is 0.5 to 30% by mass.

8. 2. The dental glass composition of claim 1, wherein the binder further comprises a wax component (D) that is solid at 25°C.

9. 2. The dental glass composition according to claim 1, wherein the content of water and propylene glycol is less than 100 ppm by mass.

10. 2. The dental glass composition according to claim 1, which is solid at 25°C.

11. 11. A method for manufacturing a dental prosthesis, comprising the steps of: applying the dental glass composition according to any one of claims 1 to 10 to a substrate of a dental prosthesis having a ceramic surface; and firing the substrate after building up dental porcelain, without firing the substrate after applying the dental glass composition and before building up dental porcelain.

12. The method for manufacturing a dental prosthesis according to claim 11, wherein the firing temperature in the firing step after building up the dental porcelain is 700 to 1100°C.

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