Composite resin teeth containing non-crosslinked polymer particles

Abstract

To provide composite resin teeth that have excellent fracture resistance to withstand occlusal pressure in the oral cavity and exhibit good adhesion to the denture base.SOLUTION: Provided is a composite resin tooth having a single-layer or multilayer structure, comprising a composite resin layer made of a polymerized cured product of a curable composition containing a polymerizable monomer (A), an organic-inorganic composite filler (B), inorganic fine particles (C), and non-crosslinked polymer particles (D), wherein the content of the non-crosslinked polymer particles (D) in the curable composition is in a range of 1 mass% or more and 5 mass% or less, and the average particle diameter of all the inorganic particles (C) contained in the curable composition is 1 μm or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to composite resin teeth as artificial teeth used in the production of dentures. [Background technology]

[0002] Traditionally, resin teeth have been used as artificial teeth, made by mixing methyl methacrylate and polymethyl methacrylate and then polymerizing and hardening them. Although resin teeth have excellent transparency, moldability, and adhesion to denture bases, they have issues with low surface hardness and are prone to wear in the oral cavity.

[0003] In contrast, composite resin teeth have a composite resin layer formed by polymerizing and curing a curable composition containing a polyfunctional (meth)acrylate-based polymerizable monomer and inorganic fine particles and / or an organic-inorganic composite filler, and therefore exhibit high surface hardness and excellent wear resistance.

[0004] Patent documents 1 and 2 propose composite resin teeth that have improved resistance to water absorption and discoloration by forming a composite resin layer from a hardenable composition containing a specific polymerizable monomer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 2517753 [Patent Document 2] Patent No. 5804517 Summary of the Invention [Problem to be solved by the invention]

[0006] Although the composite resin teeth described in Patent Documents 1 and 2 have improved mechanical properties compared to resin teeth, when the opposing teeth are prosthetics made of ceramics, zirconia, or other materials with extremely high surface hardness, their fracture resistance is insufficient to withstand the occlusal pressure in the oral cavity. Furthermore, the composite resin layer of these composite resin teeth has poor adhesion to the denture base, and when used in the oral cavity, tiny gaps form at the interface between the artificial tooth and the denture base, and plaque and pigments can be deposited in these gaps, adversely affecting appearance and hygiene.

[0007] Therefore, an object of the present invention is to provide a composite resin tooth that has excellent fracture resistance that can withstand occlusal pressure in the oral cavity, while also exhibiting good adhesion to a denture base. [Means for solving the problem]

[0008] To achieve the above-mentioned objectives, the inventors conducted extensive research and discovered that incorporating a specific amount of non-crosslinked polymer particles into the composite resin layer of a composite resin tooth results in high fracture resistance and excellent adhesion to the denture base, leading to the completion of the present invention. Specifically, in the composite resin tooth of the present invention, the non-crosslinked polymer particles incorporated into the composite resin layer absorb the stress transmitted to the composite resin layer when subjected to occlusal pressure, thereby preventing fracture. Furthermore, the presence of non-crosslinked polymer particles improves adhesion to the denture base compared to the composite resin layer of conventional composite resin teeth, and prevents the formation of minute gaps at the interface between the composite resin layer and the denture base, which can cause the deposition of plaque, pigments, etc.

[0009] That is, the above problem can be solved by using the following component composition. A composite resin tooth having a single layer structure or a layer structure of two or more layers, The present invention includes a composite resin layer made of a polymerized and cured product of a curable composition containing a polymerizable monomer (A), an organic-inorganic composite filler (B), inorganic fine particles (C), and non-crosslinked polymer particles (D), the content of the non-crosslinked polymer particles (D) in the curable composition is in the range of 1% by mass or more and 5% by mass or less, A composite resin tooth, characterized in that all of the inorganic particles (C) contained in the hardenable composition have an average particle size of 1 μm or less. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a composite resin tooth that has excellent resistance to fracture so as to withstand the occlusal pressure in the oral cavity, and that exhibits good adhesion to a denture base. [Brief explanation of the drawings]

[0011] [Figure 1] Schematic diagram showing the structure of the test specimen [Figure 2] A diagram showing the test state of the test specimen attached to a dedicated jig DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below. As used herein, a composite resin tooth refers to an artificial tooth having at least one composite resin layer, which will be described later. As used herein, a composite resin layer refers to one of the layers constituting a composite resin tooth, which is formed by polymerizing and curing a curable composition containing a polymerizable monomer and an organic-inorganic composite filler and / or inorganic fine particles.

[0013] In this specification, the non-crosslinked polymer particles refer to particles of a polymer of one or more types of monofunctional polymerizable monomers, and in particular to particles of a polymer that does not have crosslinking points between polymers.

[0014] In this specification, (meth)acrylate refers to both acrylate and methacrylate, (meth)acryloyl refers to both acryloyl and methacryloyl, (meth)acrylic acid refers to both acrylic acid and methacrylic acid, and (meth)acrylamide refers to both acrylamide and methacrylamide.

[0015] In this specification, the average particle size refers to the particle size (D50) at which the cumulative value from the small particle size side reaches 50% in the volume-based particle size distribution measured using a laser diffraction / scattering particle size distribution analyzer or the like.

[0016] The composite resin tooth of the present invention having a single layer or two or more layer structure has a composite resin layer formed by polymerizing and curing a curable composition containing a polymerizable monomer (A), an organic-inorganic composite filler (B), inorganic fine particles (C), and a specific amount of non-crosslinked polymer particles (D). These components are described in detail below.

[0017] In the present invention, the average particle size of the non-crosslinked polymer particles (D) can be set to 5 μm or more and 50 μm or less.

[0018] In the present invention, the content of the inorganic fine particles (C) in the curable composition is in the range of 15% by mass or more and 35% by mass or less, and The content of the inorganic filler (b-1) contained in the organic-inorganic composite filler (B) can be in the range of 10% by mass or more and 35% by mass or less.

[0019] In the present invention, the content of methyl methacrylate relative to the total amount of the polymerizable monomer (A) can be 5% by mass or less.

[0020] In the present invention, the non-crosslinked polymer particles (D) may include polymethyl methacrylate particles.

[0021] The polymerizable monomer (A) that can be used in the curable composition for forming a composite resin layer (hereinafter referred to as the "curable composition of the present invention") is not particularly limited in terms of its molecular structure, and any known polymerizable monomer can be used. Specifically, examples of polymerizable unsaturated groups that the polymerizable monomer (A) may have include, but are not limited to, a (meth)acryloyloxy group, a (meth)acrylamide group, a styryl group, a vinyl group, and an allyl group. Among these polymerizable unsaturated groups, a (meth)acryloyloxy group or a (meth)acrylamide group is preferred because of its excellent polymerization rate, and a (meth)acryloyloxy group is more preferred. Furthermore, the number of polymerizable unsaturated groups that the polymerizable monomer (A) may have is not particularly limited. The hydrocarbon group bonded to the polymerizable unsaturated group may be any of an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, and a combination thereof, and the hydrocarbon group may have any substituent such as an acidic group, a hydroxyl group, a halogen atom, a sulfur atom, an alkoxy group, an amino group, a glycidyl group, etc. Specific examples of the polymerizable monomer (A) are given below.

[0022] Examples of the monofunctional polymerizable monomer include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, isobutyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, sec-butyl (meth)acrylate, n-amyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate. Acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, adamantyl (meth)acrylate, phenyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, benzyl (meth)acrylate, 2-phenylethyl (meth)acrylate, o-phenoxybenzyl (meth)acrylate, m-phenoxybenzyl (meth)acrylate, p-phenoxybenzyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate ) acrylate, glycidyl (meth)acrylate, isobornyl (meth)acrylate, allyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, glycerol (meth)acrylate, (meth)acryloyloxyethyl methyl succinate, 2 (Meth)acrylic acid esters such as (meth)acryloyloxyethyl propionate, acetoacetoxyethyl (meth)acrylate, acetoacetoxypropyl (meth)acrylate, and acetoacetoxybutyl (meth)acrylate; silane compounds such as γ-(meth)acryloyloxypropyltrimethoxysilane and γ-(meth)acryloyloxypropyltriethoxysilane; amines such as 2-(N,N-dimethylamino)ethyl (meth)acrylate and 2-(N,N-diethylamino)ethyl (meth)acrylate; 2,2,Examples include fluorine-containing (meth)acrylates such as 2-trifluoroethyl (meth)acrylate, perfluorohexylethyl (meth)acrylate, and perfluorooctylethyl (meth)acrylate, as well as their (meth)acrylamides and N-methylol (meth)acrylamide.

[0023] Examples of aromatic bifunctional polymerizable monomers include 2,2-bis[4-[3-(meth)acryloyloxy-2-hydroxypropoxy]phenyl]propane, 2,2-bis(4-(meth)acryloyloxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxydiethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxytetraethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxypentaethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxydipropoxyphenyl)propane, 2-(4-(meth)acryloyloxyethoxyphenyl)- ...

[0033] Examples of the acryloyloxydiethoxyphenyl propane include 2-(4-(meth)acryloyloxydiethoxyphenyl)-2-(4-(meth)acryloyloxytriethoxyphenyl)propane, 2-(4-(meth)acryloyloxydipropoxyphenyl)-2-(4-(meth)acryloyloxytriethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxydipropoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxyisopropoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxypolyethoxyphenyl)propane, 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene, and (meth)acrylamides thereof.

[0024] Examples of the aliphatic bifunctional polymerizable monomer include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9- Examples of the acrylate include nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, glycerol-1,3-dimethacrylate, 3-hydroxypropyl-1,2-di(meth)acrylate, 2-hydroxy-3-acryloyloxypropyl (meth)acrylate, 1,2-bis(3-(meth)acryloyloxy-2-hydroxypropoxy)ethane, 1,2-bis(3-(meth)acryloyloxy-2-hydroxypropoxy)propane, 2-hydroxy-1,3-bis(3-(meth)acryloyloxy-2-hydroxypropoxy)propane, and (meth)acrylamides thereof.

[0025] Examples of the tri- or higher functional polymerizable monomer include trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolmethane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, glycerin tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and (meth)acrylamides thereof.

[0026] Examples of urethane-based polymerizable monomers include (meth)acrylate compounds having a urethane bond derived from an adduct of a polymerizable monomer having a hydroxyl group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, or 3-chloro-2-hydroxypropyl (meth)acrylate, with an isocyanate compound, such as methylcyclohexane diisocyanate, methylenebis(4-cyclohexyl isocyanate), hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, diisocyanate methylmethylbenzene, or 4,4-diphenylmethane diisocyanate.

[0027] In addition to the above polymerizable monomers, oligomers or polymers having at least one polymerizable group may also be used. The polymerizable monomer (A) shown above is not limited to these, and may be used alone or in combination.

[0028] The content of the polymerizable monomer (A) is not particularly limited, but is preferably in the range of 10% by mass to 50% by mass in the curable composition of the present invention, more preferably in the range of 25% by mass to 50% by mass, and even more preferably in the range of 25% by mass to 40% by mass. If the content of the polymerizable monomer (A) is less than 10% by mass, the fracture resistance of the composite resin layer may decrease. On the other hand, if it exceeds 50% by mass, the surface hardness, abrasion resistance, compressive strength, etc. may decrease.

[0029] Furthermore, when the polymerizable monomer (A) contains methyl methacrylate, the content of methyl methacrylate is preferably 5% by mass or less based on the total amount of the polymerizable monomer (A). If the content of methyl methacrylate exceeds 5% by mass, the surface hardness, abrasion resistance, compressive strength, fracture resistance, etc. of the composite resin layer may decrease. Preferably, the curable composition of the present invention does not contain methyl methacrylate.

[0030] The organic-inorganic composite filler (B) that can be used in the curable composition of the present invention is a composite particle consisting of an inorganic portion contained in the form of an inorganic filler (b-1) and an organic portion formed by curing a polymerizable monomer (b-2), and the inorganic filler (b-1) exists in a dispersed state in a cured product of the polymerizable monomer (b-2). The organic-inorganic composite filler (B) can be obtained by making the inorganic filler (b-1) and the polymerizable monomer (b-2) containing a polymerization initiator as uniform as possible, curing the polymerizable monomer (b-2), and optionally pulverizing the cured product.

[0031] The inorganic filler (b-1) that can be used to produce the organic-inorganic composite filler (B) will be described. The inorganic filler (b-1) is not particularly limited in terms of its constituent elements, and known fillers can be used. Specific examples of the inorganic filler (b-1) include inorganic oxides such as silica, alumina, titania, zirconia, strontium oxide, barium oxide, yttrium oxide, lanthanum oxide, and ytterbium oxide; inorganic composite oxides such as silica-zirconia, silica-titania, silica-titania-barium oxide, and silica-titania-zirconia; fused silica, quartz, aluminosilicate glass, fluoroaluminosilicate glass, borosilicate glass, aluminoborate glass, and boroaluminosilicate glass; and metal fluorides such as calcium fluoride, barium fluoride, strontium fluoride, yttrium fluoride, lanthanum fluoride, and ytterbium fluoride.

[0032] The shape of these inorganic fillers (b-1) is not particularly limited, and they may be any shape such as spherical, needle-like, plate-like, crushed, or scaly, and there is no problem even if they are aggregates of these. The inorganic fillers (b-1) shown above are not limited to these, and they may be used alone or in combination.

[0033] While there are no particular limitations on the particle size of the inorganic filler (b-1), considering the balance of various properties in the composite resin layer, an average particle size of 0.005 μm or more and 3 μm or less is preferred. If the average particle size of the inorganic filler (b-1) is less than 0.005 μm, the inorganic filler (b-1) will aggregate significantly, making it difficult to uniformly disperse the inorganic filler (b-1) in the organic-inorganic composite filler (B), which may result in a decrease in the compressive strength and fracture resistance of the composite resin layer. Furthermore, if the average particle size of the inorganic filler (b-1) exceeds 3 μm, the abrasiveness of the composite resin layer will decrease, resulting in a failure to obtain a smooth surface and a tendency for discoloration to occur. In addition, the curable composition of the present invention may also be composed solely of inorganic fillers (b-1) constituting the organic-inorganic composite filler (B) with an average particle size of 0.005 μm or more and 3 μm or less.

[0034] These inorganic fillers (b-1) are preferably subjected to a surface treatment to be hydrophobic. This surface treatment allows for a high loading of the inorganic filler (b-1) in the organic-inorganic composite filler (B), thereby improving the mechanical properties of the organic-inorganic composite filler (B) itself. There are no particular limitations on the surface treatment agent that can be used for the surface treatment of the inorganic filler (b-1), and known agents such as organosilicon compounds, organozirconium compounds, organotitanium compounds, and organoaluminum compounds can be used, but organosilicon compounds are the most commonly used. Specific examples of organosilicon compounds include, but are not limited to, methyltrimethoxysilane, ethyltrimethoxysilane, methoxytripropylsilane, propyltriethoxysilane, hexyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltrichlorosilane, vinyltri(β-methoxyethoxy)silane, γ-(meth)acryloyloxypropyltrimethoxysilane, 8-(meth)acryloyloxyoctyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, methyltrichlorosilane, phenyltrichlorosilane, trimethylsilyl isocyanate, vinylsilyl triisocyanate, phenylsilyl triisocyanate, and hexamethyldisilazane. These surface treatment agents can be used alone or in combination. Furthermore, the surface treatment method is not particularly limited, and known methods can be used. Furthermore, the amount of the surface treatment agent relative to the inorganic filler (b-1) when performing the surface treatment is not particularly limited, and may be adjusted appropriately depending on the particle size of the inorganic filler (b-1), etc.

[0035] The content of inorganic filler (b-1) contained in the raw materials of organic-inorganic composite filler (B) is preferably 8% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 35% by mass or less. If the content of inorganic filler (b-1) in organic-inorganic composite filler (B) is less than 8% by mass, the surface hardness, abrasion resistance, compressive strength, etc. of the composite resin layer may decrease. On the other hand, if the content of inorganic filler (b-1) exceeds 50% by mass, the brittleness of organic-inorganic composite filler (B) may increase, and the fracture resistance of the composite resin layer may decrease. Note that in the curable composition of the present invention, organic-inorganic composite filler (B) may also contain 8% by mass or more and 50% by mass or less of inorganic filler (b-1) having an average particle diameter of 0.005 μm or more and 3 μm or less. The curable composition of the present invention may contain, as the organic-inorganic composite filler (B), only an organic-inorganic composite filler in which the content of the inorganic filler (b-1) contained in the raw materials is 8% by mass or more and 50% by mass or less. The curable composition of the present invention may contain, as the organic-inorganic composite filler (B), only an organic-inorganic composite filler containing 8% by mass or more and 50% by mass or less of the inorganic filler (b-1) having an average particle size of 0.005 μm or more and 3 μm or less.

[0036] The polymerizable monomer (b-2) that can be used to produce the organic-inorganic composite filler (B) is not particularly limited in its molecular structure, and the same polymerizable monomer as the aforementioned polymerizable monomer (A) can be used.

[0037] The content of the polymerizable monomer (b-2) contained in the raw materials of the organic-inorganic composite filler (B) is preferably 48% by mass or more and 90% by mass or less, more preferably 63% by mass or more and 88% by mass or less. If the content of the polymerizable monomer (b-2) in the organic-inorganic composite filler (B) is less than 48% by mass, the brittleness of the organic-inorganic composite filler (B) may increase, and the fracture resistance of the composite resin layer may decrease. On the other hand, if the content of the polymerizable monomer (b-2) exceeds 90% by mass, the surface hardness, abrasion resistance, compressive strength, etc. of the composite resin layer may decrease.

[0038] Next, polymerization initiators that can be used in the production of the organic-inorganic composite filler (B) will be described. There are no particular limitations on the polymerization initiator, and known polymerization initiators such as thermal polymerization initiators, chemical polymerization initiators, and photopolymerization initiators can be used. Among these, thermal polymerization initiators are preferred because they offer superior production efficiency for the organic-inorganic composite filler (B). Suitable thermal polymerization initiators include organic peroxides such as benzoyl peroxide and azo compounds such as azobisisobutyronitrile. These polymerization initiators can be used alone or in combination, regardless of the polymerization mode or method. There are no particular limitations on the amount of polymerization initiator added, but it is generally 0.1% by mass or more and 10% by mass or less, based on 100% by mass of all polymerizable monomers (b-2) used in the production of the organic-inorganic composite filler (B).

[0039] Next, a method for producing the organic-inorganic composite filler (B) will be described using a thermal polymerization initiator as an example. The organic-inorganic composite filler (B) is produced through the following main steps (Step 1) to (Step 4): (Step 1) mixing the components constituting the organic-inorganic composite filler, such as a polymerizable monomer, a thermal polymerization initiator, and an inorganic filler, to obtain a mixture; (Step 2) applying heat to the mixture to polymerize the polymerizable monomer and obtain a cured product; (Step 3) optionally pulverizing the cured product to obtain an organic-inorganic composite filler; and (Step 4) optionally surface-treating the organic-inorganic composite filler. For the composite resin layer, the pulverized organic-inorganic composite filler obtained in (Step 3) may be used as is, or the surface-treated organic-inorganic composite filler obtained in (Step 4) may be used. Furthermore, if the organic-inorganic composite filler is already in the form of fine particles rather than in a lump form at the stage of (Step 2), it may be used as is as the organic-inorganic composite filler. Furthermore, the organic-inorganic composite filler may be surface-treated in (Step 4) before use.

[0040] Examples of the process for obtaining a mixture of the components in (Step 1) include, but are not limited to, a method of mixing the components, such as a polymerizable monomer, a thermal polymerization initiator, and an inorganic filler, using a kneader; a method of aggregating the inorganic filler to obtain pore-containing aggregated fillers measuring several micrometers to several tens of micrometers, then immersing the aggregated fillers in a solution of a thermal polymerization initiator and a polymerizable monomer dissolved in an organic solvent to form a slurry; and then removing the organic solvent at low temperature and under reduced pressure to allow the polymerizable monomer to penetrate and coat the interior and surface of the aggregated filler, thereby mixing the components; or a method of press-molding the inorganic filler to obtain an inorganic filler molded body, then immersing the molded body in a polymerizable monomer containing a thermal polymerization initiator, thereby allowing the polymerizable monomer to penetrate the interior of the molded body and mix the components. In addition, in this process, by dissolving a surface treatment agent such as the aforementioned organosilicon compound in the polymerizable monomer, surface treatment of the inorganic filler and mixing of the components can be performed simultaneously. This eliminates the need for a surface treatment of the inorganic filler prior to mixing the components.

[0041] In the step of obtaining a cured product (step 2), the polymerization temperature and polymerization time can be adjusted as appropriate depending on the properties of the thermal polymerization initiator used and based on the heat-induced discoloration of the organic-inorganic composite filler and the amount of residual unpolymerized monomer, but generally the polymerization temperature is 70°C or higher and 150°C or lower, and the polymerization time is several minutes to several hours. Furthermore, polymerization conditions can be selected as appropriate depending on the polymerization method, such as polymerization in air, polymerization in an inert gas atmosphere such as nitrogen or argon, polymerization under normal pressure, or polymerization under pressure.

[0042] In (Step 3) the step of obtaining an organic-inorganic composite filler by pulverization, the pulverization method is not particularly limited and may be either a wet or dry pulverization method. Examples of pulverizers used for pulverization include, but are not limited to, high-speed rotary mills such as hammer mills and turbo mills, container-driven mills such as ball mills, planetary mills, and vibration mills, media-agitating mills such as attritors and bead mills, and jet mills. The average particle size of the organic-inorganic composite filler (B) is not particularly limited and can be adjusted appropriately depending on the desired properties to be imparted to the composite resin layer. However, the average particle size is preferably 1 μm or more and 100 μm or less, and more preferably 10 μm or more and 30 μm or less. An organic-inorganic composite filler with an average particle size of less than 1 μm requires a long time for pulverization to obtain it, which can cause discoloration of the organic-inorganic composite filler itself, which can adversely affect the color tone of the composite resin layer. Furthermore, a particle size exceeding 100 μm can reduce the compressive strength of the composite resin layer. The curable composition of the present invention may contain only an organic-inorganic composite filler having an average particle size of 1 μm or more and 100 μm or less as the organic-inorganic composite filler (B).

[0043] In (Step 4), the step of surface treating the organic-inorganic composite filler, the same surface treatment agent as that which can be used for the surface treatment of the inorganic filler described above can be used. Furthermore, as with the surface treatment of the inorganic filler, a known method can be used for the surface treatment. Furthermore, the amount of the surface treatment agent relative to the organic-inorganic composite filler when performing the surface treatment is not particularly limited, and may be adjusted appropriately depending on the particle size of the organic-inorganic composite filler, but is preferably 0.1 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the organic-inorganic composite filler.

[0044] The content of the organic-inorganic composite filler (B) is not particularly limited, but is preferably in the range of 30% by mass to 60% by mass, more preferably 35% by mass to 55% by mass, in the curable composition of the present invention. If the content of the organic-inorganic composite filler (B) is less than 30% by mass, the brittleness of the composite resin layer may increase and the fracture resistance may decrease. On the other hand, if the content exceeds 60% by mass, the surface hardness, abrasion resistance, compressive strength, etc. may decrease.

[0045] The inorganic fine particles (C) that can be used in the curable composition of the present invention are not particularly limited in their constituent elements, and known ones can be used.Specific examples include silica, alumina, titania, silica-titania, silica-titania-barium oxide, silica-zirconia, silica-alumina, lanthanum glass, borosilicate glass, soda glass, barium glass, strontium glass, glass ceramic, aluminosilicate glass, barium boroaluminosilicate glass, strontium boroaluminosilicate glass, fluoroaluminosilicate glass, calcium fluoroaluminosilicate glass, strontium fluoroaluminosilicate glass, barium fluoroaluminosilicate glass, strontium calcium fluoroaluminosilicate glass, etc.

[0046] The shape of these inorganic fine particles (C) is not particularly limited, and they may be any shape such as spherical, needle-like, plate-like, crushed, scale-like, etc. Furthermore, there is no problem even if they are aggregates of these. The inorganic fine particles (C) shown above are not limited to these, and further, they may be used alone or in combination of two or more.

[0047] In the present invention, the average particle size of all inorganic fine particles (C) contained in the curable composition must be 1 μm or less to impart good fracture resistance, excellent abrasion resistance, and surface smoothness to the composite resin layer. If the average particle size of the inorganic fine particles (C) exceeds 1 μm, the fracture resistance of the composite resin layer decreases. Furthermore, due to the decreased abrasion resistance, a smooth surface cannot be obtained and discoloration is likely to occur. In the present invention, inorganic particles having an average particle size exceeding 1 μm can be contained in an amount that does not impair the effects of the present invention. The amount of inorganic particles having an average particle size exceeding 1 μm that does not impair the effects of the present invention can be less than 1 mass%, less than 0.5 mass%, less than 0.1 mass%, less than 0.05 mass%, less than 0.01 mass%, or less than 0.001 mass% in the curable composition of the present invention. In the present invention, inorganic particles having an average particle size exceeding 1 μm can be contained. In the present invention, inorganic particles having an average particle size exceeding 1 μm can be contained.

[0048] The inorganic fine particles (C) may be surface-treated using a surface treatment agent or the like. Specific examples of surface treatment agents include surfactants, organic acids, inorganic acids, organosilicon compounds, organozirconium compounds, organotitanium compounds, organoaluminum compounds, and metal alkoxide compounds, with organosilicon compounds being the most commonly used. The organosilicon compounds can be the same as those used for the surface treatment of the inorganic filler (b-1) described above. Specific examples of surface treatment methods include spraying a surface treatment agent onto fluidized inorganic fine particles, or dispersing inorganic fine particles in a solution containing a surface treatment agent. The surface treatment agents and surface treatment methods are not limited to these, and can be used alone or in combination. Furthermore, the amount of surface treatment agent relative to the inorganic fine particles (C) during surface treatment is not particularly limited and can be adjusted appropriately depending on the particle size of the inorganic fine particles (C).

[0049] The content of inorganic fine particles (C) is not particularly limited, but is preferably in the range of 10% by mass to 50% by mass, more preferably 15% by mass to 35% by mass, in the curable composition of the present invention. If the content of inorganic fine particles (C) is less than 10% by mass, the surface hardness, abrasion resistance, compressive strength, etc. of the composite resin layer may decrease. On the other hand, if it exceeds 50% by mass, the brittleness of the composite resin layer may increase, and the fracture resistance may decrease.

[0050] The non-crosslinked polymer particles (D) that can be used in the curable composition of the present invention include particles of homopolymers of the monofunctional polymerizable monomers having the (meth)acryloyloxy group or (meth)acrylamide group described above, particles of copolymers combining two or more of these, and particles of copolymers combining monofunctional polymerizable monomers having the (meth)acryloyloxy group or (meth)acrylamide group with other monofunctional polymerizable monomers such as styrene, α-methylstyrene, isoprene, butadiene, isobutylene, vinyl acetate, vinyl chloride, vinyl alcohol, ethylene, propylene, maleic acid, itaconic acid, and maleic anhydride. Furthermore, particles of homopolymers of the other monofunctional polymerizable monomers described above and particles of copolymers combining two or more of these can also be used without any problems. Furthermore, the copolymer particles may be any copolymer, such as a random copolymer, an alternating copolymer, or a block copolymer.

[0051] Among these non-crosslinked polymer particles (D), it is preferable to use particles of homopolymers of monofunctional polymerizable monomers having (meth)acryloyloxy groups, which are the most commonly used in dental materials, or particles of copolymers combining two or more types. Specific examples of such non-crosslinked polymer particles (D) include, but are not limited to, particles of homopolymers such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, as well as particles of copolymers combining two or more types. These non-crosslinked polymer particles (D) can be used alone or in combination. Furthermore, it is more preferable to use polymethyl methacrylate particles or copolymer particles of methyl methacrylate and ethyl methacrylate as the non-crosslinked polymer particles (D), and polymethyl methacrylate particles are most preferable. The use of these non-crosslinked polymer particles (D) can improve the fracture resistance and compressive strength of the composite resin layer in a balanced manner. The curable composition of the present invention may contain, as the non-crosslinked polymer particles (D), only particles of a homopolymer of a monofunctional polymerizable monomer having a (meth)acryloyloxy group and / or particles of a copolymer combining two or more types, may contain only polymethyl methacrylate particles and / or copolymer particles of methyl methacrylate and ethyl methacrylate, or may contain only polymethyl methacrylate particles.

[0052] The polymerization method for producing these non-crosslinked polymer particles (D) is not particularly limited, and any polymerization method such as emulsion polymerization or suspension polymerization can be used without any problem. The shape of these non-crosslinked polymer particles (D) can be any shape, including spherical, crushed, and hollow, but spherical is preferred. The weight-average molecular weight of the non-crosslinked polymer particles (D) is not particularly limited, but the average particle diameter is preferably 1 μm or more and preferably in the range of 150,000 to 1,500,000. Here, the weight-average molecular weight refers to the average molecular weight calculated based on the molecular weight distribution measured by gel permeation chromatography. The curable composition of the present invention may contain, as the non-crosslinked polymer particles (D), only non-crosslinked polymer particles having a weight-average molecular weight of 10,000 to 2,000,000, only non-crosslinked polymer particles having a weight-average molecular weight of 50,000 to 1,500,000, or only non-crosslinked polymer particles having a weight-average molecular weight of 100,000 to 1,500,000.

[0053] Furthermore, the average particle size of the non-crosslinked polymer particles (D) is preferably in the range of 1 μm to 100 μm, more preferably in the range of 1 μm to 80 μm, and even more preferably in the range of 5 μm to 50 μm. If the average particle size of the non-crosslinked polymer particles (D) is less than 1 μm, the compressive strength of the composite resin layer may decrease. If the average particle size exceeds 100 μm, the adhesiveness of the composite resin layer to the denture base may decrease. The curable composition of the present invention may contain, as the non-crosslinked polymer particles (D), only non-crosslinked polymer particles having an average particle size of 1 μm to 100 μm, only non-crosslinked polymer particles having an average particle size of 3 μm to 80 μm, or only non-crosslinked polymer particles having an average particle size of 5 μm to 50 μm. The curable composition of the present invention may contain, as the non-crosslinked polymer particles (D), only non-crosslinked polymer particles having a weight-average molecular weight of 10,000 to 2,000,000 and an average particle size of 1 μm to 100 μm.

[0054] The content of the non-crosslinked polymer particles (D) in the curable composition of the present invention must be in the range of 1% by mass to 5% by mass. If the content of the non-crosslinked polymer particles (D) is less than 1% by mass, the fracture resistance of the composite resin layer and the adhesion to the denture base decrease. If the content exceeds 5% by mass, the surface hardness, abrasion resistance, compressive strength, etc. of the composite resin layer decrease.

[0055] The curable composition of the present invention preferably contains a polymerization initiator. Polymerization initiators include those that initiate radical polymerization by heating (thermal polymerization initiators), those that initiate radical polymerization through the action of a compound consisting of two or more components, such as redox initiators (sometimes called "chemical polymerization initiators" in the dental field; hereinafter referred to as "chemical polymerization initiators"), and those that initiate radical polymerization by light irradiation (photopolymerization initiators). In the present invention, any of these polymerization initiators can be used without any restrictions. However, it is preferable to use a thermal polymerization initiator, as this facilitates molding of the composite resin layer and facilitates obtaining high mechanical properties.

[0056] Specific examples of thermal polymerization initiators include, but are not limited to, organic peroxides such as benzoyl peroxide, parachlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, acetyl peroxide, lauroyl peroxide, tertiary butyl peroxide, cumene hydroperoxide, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 2,5-dihydroperoxide, methyl ethyl ketone peroxide, and tertiary butyl peroxybenzoate, and azo compounds such as azobisisobutyronitrile, azobisisobutyrate methyl, and azobiscyanovaleric acid. These thermal polymerization initiators can be used alone or in combination. Of these thermal polymerization initiators, benzoyl peroxide and / or azobisisobutyronitrile are most preferred.

[0057] Examples of chemical polymerization initiators include, but are not limited to, organic peroxide / amine compound, organic peroxide / amine compound / sulfinate, organic peroxide / amine compound / borate compound, etc. These chemical polymerization initiators can be used alone or in combination.

[0058] Examples of photopolymerization initiators include, but are not limited to, α-diketones, benzophenones, acylphosphine oxides, α-aminoacetophenones, ketals, coumarins, and titanocenes. Examples of photopolymerization accelerators include, but are not limited to, tertiary amines, triazine compounds, diaryliodonium salts, tin compounds, aldehyde compounds, and sulfur-containing compounds. These photopolymerization initiators and photopolymerization accelerators can be used alone or in combination.

[0059] The content of the polymerization initiator is not particularly limited, but is preferably 0.1 to 1.5 parts by mass per 100 parts by mass of the total content of the polymerizable monomer (A) and the polymerization initiator. If the content of the polymerization initiator is less than 0.1 part by mass, the polymerization of the curable composition of the present invention will be insufficient, which may result in a decrease in various mechanical properties of the composite resin layer or in the composite resin layer becoming more susceptible to coloration. Furthermore, if the content exceeds 1.5 parts by mass, the composite resin layer may become discolored.

[0060] In addition to the components (A) to (D) described above, the curable composition of the present invention may optionally contain, as needed, an ultraviolet absorber such as 2-hydroxy-4-methylbenzophenone, a polymerization inhibitor such as hydroquinone, hydroquinone monomethyl ether, or 2,5-ditertiarybutyl-4-methylphenol, a chain transfer agent, a discoloration inhibitor, an antibacterial agent, a color pigment, or other conventionally known additives.

[0061] The composite resin tooth of the present invention may have a single-layer structure or a layer structure of two or more layers. When the composite resin tooth has a layer structure of two or more layers, at least one layer is a composite resin layer formed by polymerizing and curing the curable composition of the present invention. The composite resin tooth of the present invention may have a single-layer structure consisting of only a composite resin layer, or a layer structure consisting of two or more composite resin layers. There are no particular restrictions on the materials constituting the layers other than the composite resin layer. However, as with conventional composite resin teeth, it is preferable that the composite resin layer be an acrylic resin layer mainly composed of polymethylmethacrylate, which is formed by mixing a liquid material mainly composed of methylmethacrylate with a powder material mainly composed of polymethylmethacrylate and then polymerizing and curing the mixture. Furthermore, when the composite resin tooth has a layer structure of two or more layers, it is preferable that the outermost layer, including the labial surface, of an anterior tooth, or the outermost layer, including the occlusal surface, of a molar tooth, be a composite resin layer. This reduces the wear rate of the composite resin tooth of the present invention in the oral cavity.

[0062] There are no particular restrictions on the shape and size of the composite resin tooth of the present invention, nor on the shape and size of each layer, and there is no problem if it has retention holes to ensure mechanical engagement with the denture base.

[0063] There are no particular limitations on the method for producing the composite resin tooth of the present invention, and it can be produced by methods such as compression molding, injection molding, and injection compression molding, but is not limited to these. [Example]

[0064] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. The various components used to prepare the curable compositions of the examples and comparative examples, and their abbreviations, are as follows:

[0065] [Polymerizable monomer (A)] UDMA: Urethane dimethacrylate UDA: 1,6-bis[(2-phenoxy-2'-acryloxy)isopropyl-oxy-carbonylamino]hexane Bis-GMA: 2,2-bis[4-[2-hydroxy-3-(methacryloyloxy)propyloxy]phenyl]propane TEGDMA: Triethylene glycol dimethacrylate MMA: Methyl methacrylate

[0066] [Organic-inorganic composite filler (B)] O1: Organic-inorganic composite filler 1 (average particle size: 23 μm, content of inorganic filler (b-1): 18 mass%, average particle size of inorganic filler (b-1): 16 nm) O2: Organic-inorganic composite filler 2 (average particle size: 20 μm, content of inorganic filler (b-1): 32.5 mass%, average particle size of inorganic filler (b-1): 9 nm) O3: Organic-inorganic composite filler 3 (average particle size: 28 μm, content of inorganic filler (b-1): 50 mass%, average particle size of inorganic filler (b-1): 16 nm) O4: Organic-inorganic composite filler 4 (average particle size: 20 μm, content of inorganic filler (b-1): 12 mass%, average particle size of inorganic filler (b-1): 16 nm) O5: Organic-inorganic composite filler 5 (average particle size: 25 μm, content of inorganic filler (b-1): 35 mass%, average particle size of inorganic filler (b-1): 16 nm) O6: Organic-inorganic composite filler 6 (average particle size: 30 μm, content of inorganic filler (b-1): 10 mass%, average particle size of inorganic filler (b-1): 16 nm) O7: Organic-inorganic composite filler 7 (average particle size: 55 μm, content of inorganic filler (b-1): 75 mass%, average particle size of inorganic filler (b-1): 4 μm) O8: Organic-inorganic composite filler 8 (average particle size: 22 μm, content of inorganic filler (b-1): 50 mass%, average particle size of inorganic filler (b-1): 3 μm)

[0067] [Inorganic fine particles (C) with an average particle size of 1 μm or less] I1: Fumed silica (Aerosil OX-50 (Evоnik Industries), average particle size: 40 nm) I2: Fumed silica (Aerosil R-972 (Evоnik Industries), average particle size: 16 nm) [Other inorganic fine particles (C')] I´1: Spherical silica (average particle size: 3 μm) I´2: Crushed silica (average particle size: 1.5 μm)

[0068] [Non-crosslinked polymer particles (D)] nCP1: Polymethyl methacrylate (average particle size: 8 μm, weight-average molecular weight: approximately 800,000, shape: spherical) nCP2: Polymethyl methacrylate (average particle size: 50 μm, weight-average molecular weight: approximately 1 million, shape: spherical) nCP3: Polymethyl methacrylate (average particle size: 80 μm, weight-average molecular weight: approximately 1 million, shape: spherical) nCP4: Polymethyl methacrylate (average particle size: 4 μm, weight-average molecular weight: approximately 800,000, shape: spherical) nCP5: Copolymer of methyl methacrylate (MMA) and ethyl methacrylate (EMA) (MMA / EMA = 70 / 30) (average particle size: 65 μm, weight-average molecular weight: approximately 350,000, shape: spherical) nCP6: Polyethyl methacrylate (average particle size: 4 μm, weight-average molecular weight: approximately 40,000, shape: spherical) nCP7: Polymethyl methacrylate (average particle size: 1.5 μm, weight-average molecular weight: approximately 150,000, shape: spherical) nCP8: Polymethyl methacrylate (average particle size: 0.4 μm, weight-average molecular weight: approximately 1.5 million, shape: spherical) nCP9: Polymethyl methacrylate (average particle size: 120 μm, weight-average molecular weight: approximately 1.6 million, shape: spherical) nCP10: Polymethyl methacrylate (average particle size: 5 μm, weight-average molecular weight: approximately 300,000, shape: spherical) nCP11: Polymethyl methacrylate (average particle size: 100 μm, weight-average molecular weight: approximately 1 million, shape: spherical)

[0069] [Crosslinked polymer particles (D')] CP1: Cross-linked polymethyl methacrylate (average particle size: 2.2 μm, shape: spherical) CP2: Cross-linked polyurethane (average particle size: 6 μm, shape: spherical)

[0070] [Polymerization initiator] BPO: Benzoyl peroxide

[0071] [Production of organic-inorganic composite filler (B)] <Production of Organic-Inorganic Composite Filler 1 (O1)> A resin mixture was obtained by mixing 80 parts by weight of UDMA, 20 parts by weight of ethylene glycol dimethacrylate, and 0.3 parts by weight of BPO. 82 parts by weight of this resin mixture was kneaded with 18 parts by weight of Aerosil R972 until homogeneous, and then the kneaded mixture was heated at 100°C for 4 hours under a nitrogen atmosphere to obtain a cured product. The resulting cured product was pulverized to an average particle size of 23 μm to obtain organic-inorganic composite filler 1 (O1). The average particle size was measured using a laser diffraction particle size analyzer (Microtrac MT3300EXII, manufactured by Microtrac Bell).

[0072] <Production of organic-inorganic composite filler 2 (O2)> A resin mixture was obtained by mixing 80 parts by weight of UDMA, 20 parts by weight of ethylene glycol dimethacrylate, and 0.5 parts by weight of BPO. 67.5 parts by weight of this resin mixture and 32.5 parts by weight of Aerosil R711 were kneaded until homogeneous, and the kneaded mixture was heated at 100°C for 4 hours under a nitrogen atmosphere to obtain a cured product. The resulting cured product was pulverized to an average particle size of 20 μm to obtain organic-inorganic composite filler 2 (O2). The average particle size was measured using a laser diffraction particle size analyzer (Microtrac MT3300EXII, manufactured by Microtrac Bell).

[0073] <Production of Organic-Inorganic Composite Filler 3 (O3)> A resin mixture was obtained by mixing 50 parts by weight of UDMA, 50 parts by weight of neopentyl glycol dimethacrylate, and 1.0 part by weight of BPO. 50 parts by weight of this resin mixture was kneaded with 50 parts by weight of Aerosil R972 until homogeneous, and then the kneaded mixture was heated at 100°C for 4 hours under a nitrogen atmosphere to obtain a cured product. The resulting cured product was pulverized to an average particle size of 28 μm to obtain organic-inorganic composite filler 3 (O3). The average particle size was measured using a laser diffraction particle size analyzer (Microtrac MT3300EXII, manufactured by Microtrac Bell).

[0074] <Production of Organic-Inorganic Composite Filler 4 (O4)> A resin mixture was obtained by mixing 80 parts by weight of UDMA, 20 parts by weight of ethylene glycol dimethacrylate, and 0.3 parts by weight of BPO. 88 parts by weight of this resin mixture was kneaded with 12 parts by weight of Aerosil R972 until homogeneous, and then the kneaded mixture was heated at 100°C for 4 hours under a nitrogen atmosphere to obtain a cured product. The resulting cured product was pulverized to an average particle size of 20 μm to obtain organic-inorganic composite filler 4 (O4). The average particle size was measured using a laser diffraction particle size analyzer (Microtrac MT3300EXII, manufactured by Microtrac Bell).

[0075] <Production of Organic-Inorganic Composite Filler 5 (O5)> A resin mixture was obtained by mixing 80 parts by weight of UDMA, 20 parts by weight of ethylene glycol dimethacrylate, and 0.3 parts by weight of BPO. 65 parts by weight of this resin mixture and 35 parts by weight of Aerosil R972 were kneaded until homogeneous, and the kneaded mixture was heated at 100°C for 4 hours under a nitrogen atmosphere to obtain a cured product. The resulting cured product was pulverized to an average particle size of 25 μm to obtain organic-inorganic composite filler 5 (O5). The average particle size was measured using a laser diffraction particle size analyzer (Microtrac MT3300EXII, manufactured by Microtrac Bell).

[0076] <Production of Organic-Inorganic Composite Filler 6 (O6)> A resin mixture was obtained by mixing 80 parts by weight of UDMA, 20 parts by weight of ethylene glycol dimethacrylate, and 0.3 parts by weight of BPO. 90 parts by weight of this resin mixture was kneaded with 10 parts by weight of Aerosil R972 until homogeneous, and then the kneaded mixture was heated at 100°C for 4 hours under a nitrogen atmosphere to obtain a cured product. The resulting cured product was pulverized to an average particle size of 30 μm to obtain organic-inorganic composite filler 6 (O6). The average particle size was measured using a laser diffraction particle size analyzer (Microtrac MT3300EXII, manufactured by Microtrac Bell).

[0077] <Production of Organic-Inorganic Composite Filler 7 (O7)> A surface treatment solution (total mass: 11.5 parts by mass) was prepared by mixing 3.0 parts by mass of γ-methacryloyloxypropyltrimethoxysilane, 0.5 parts by mass of ion-exchanged water, and 8.0 parts by mass of anhydrous ethanol. Next, various raw materials, including silica, alumina, aluminum phosphate, sodium fluoride, and strontium carbonate (glass composition: 26.4% by mass of SiO, 29.3% by mass of AlO, 20.5% by mass of SrO, 10.9% by mass of PO, 2.5% by mass of NaO, and 10.4% by mass of F), were mixed, and the raw material mixture was melted in a melting furnace at 1400°C. The melt was removed from the melting furnace and quenched in water to obtain fluoroaluminosilicate glass. The resulting fluoroaluminosilicate glass was pulverized to a 50% particle size (D50) of 4 μm, yielding a fluoroaluminosilicate glass powder. The surface treatment solution and 100 parts by weight of the fluoroaluminosilicate glass powder were then dry-mixed and heat-treated at 110°C for 5 hours using a hot air dryer to obtain a surface-treated glass powder. Furthermore, 50 parts by weight of Bis-GMA, 50 parts by weight of triethylene glycol dimethacrylate, and 0.2 parts by weight of BPO were mixed to obtain a resin mixture. 25 parts by weight of the resin mixture and 75 parts by weight of the surface-treated glass powder were kneaded until homogeneous, and the kneaded mixture was heated at 100°C for 4 hours under a nitrogen atmosphere to obtain a cured product. The resulting cured product was pulverized to a 50% particle size (D50) of 55 μm to obtain organic-inorganic composite filler 7 (O7). The 50% particle size (D50) was measured using a laser diffraction particle size analyzer (Microtrac MT3300EXII, manufactured by Microtrac Bell).

[0078] <Production of Organic-Inorganic Composite Filler 8 (O8)> A surface treatment solution (total mass: 11.5 parts by mass) was prepared by mixing 3.0 parts by mass of γ-methacryloyloxypropyltrimethoxysilane, 0.5 parts by mass of ion-exchanged water, and 8.0 parts by mass of anhydrous ethanol. Next, various raw materials, including silica, alumina, aluminum phosphate, sodium fluoride, and strontium carbonate (glass composition: 26.4% by mass of SiO, 29.3% by mass of AlO, 20.5% by mass of SrO, 10.9% by mass of PO, 2.5% by mass of NaO, and 10.4% by mass of F), were mixed, and the raw material mixture was melted in a melting furnace at 1400°C. The melt was removed from the melting furnace and quenched in water to obtain fluoroaluminosilicate glass. The resulting fluoroaluminosilicate glass was pulverized to a 50% particle size (D50) of 3 μm, yielding a fluoroaluminosilicate glass powder. The surface treatment solution and 100 parts by weight of the fluoroaluminosilicate glass powder were then dry-mixed and heat-treated at 110°C for 5 hours using a hot air dryer to obtain a surface-treated glass powder. Furthermore, 50 parts by weight of Bis-GMA, 50 parts by weight of triethylene glycol dimethacrylate, and 0.2 parts by weight of BPO were mixed to obtain a resin mixture. 50 parts by weight of the resin mixture and 50 parts by weight of the surface-treated glass powder were kneaded until homogeneous, and the kneaded mixture was heated at 100°C for 4 hours under a nitrogen atmosphere to obtain a cured product. The resulting cured product was pulverized to a 50% particle size (D50) of 40 μm to obtain organic-inorganic composite filler 8 (O8). The 50% particle size (D50) was measured using a laser diffraction particle size analyzer (Microtrac MT3300EXII, manufactured by Microtrac Bell).

[0079] The curable compositions of the Examples and Comparative Examples were prepared by mixing the various components in the proportions shown in Tables 1 to 3. The prepared curable compositions were evaluated for surface hardness, compressive strength, compressive displacement, and adhesion to denture base materials according to the test methods shown below. In this specification, compressive displacement is used as an index of the fracture resistance of a material, and it is determined that the greater the compressive displacement, the better the fracture resistance.

[0080] [Surface hardness] Surface hardness was measured according to ISO 6507-1:2018 using the following procedure. Each curable composition was filled into a mold (25 mm diameter, 2.5 mm thick) and then subjected to pressure and heat molding (pressing pressure: 3 tons, molding temperature: 120°C, pressing time: 5 minutes). The resulting cured product was polished to a thickness of 2 mm or more, and used as a test specimen. The surface hardness of each test specimen was measured using a micro Vickers hardness tester HM-102 (Mitsutoyo Corporation) at 23±5°C and HV0.2. A surface hardness of 30 or higher was considered to be excellent.

[0081] [Compressive strength and compressive displacement] In accordance with JIS T 6603:1994, compressive strength and compressive displacement were measured according to the following procedure. Each curable composition was filled into a mold (Φ6 mm, height 12 mm) and then pressure- and heat-molded (pressing pressure: 3 t, molding temperature 120°C, pressing time 5 minutes). The resulting cured product was immersed in water at 37°C for 24 hours to prepare a test specimen. The compressive strength and compressive displacement of each test specimen were measured using an Instron universal testing machine (model: 5567A) at a crosshead speed of 1 mm / min. Compressive strength and compressive displacement were evaluated according to the following evaluation criteria. A grade of A or B was considered to indicate good compressive strength and fracture resistance, respectively. <Evaluation criteria> <<Compression strength>> A:500MPa or more B: 430 MPa or more and less than 500 MPa C: Less than 430 MPa <<Compression displacement>> A: 4.0mm or more B: 3.5mm or more and less than 4.0mm C: Less than 3.5 mm

[0082] [Adhesion to denture base materials] Adhesion to denture base materials was evaluated in accordance with ISO 22112:2017 using the following procedure. Each curable composition was filled into a mold shaped like a maxillary anterior tooth (NC Verasia Anterior, manufactured by Shofusha Co., Ltd.) and then pressurized and heated for 5 minutes to produce artificial teeth. A 30 x 10 x 6 mm piece of wax was prepared, and a 10 x 6 mm surface was melted using a hot plate or similar. The center of the lingual surface of the artificial tooth was pressed approximately 2.5 mm into the wax, and the wax was then held in place until cooled, thereby securing the artificial tooth to the wax. The artificial tooth was then embedded in plaster using a dental flask, after which the wax was rinsed off with boiling water. The wax-removed area was filled with denture base material "Shofu Urban 8S" (manufactured by Shofu Co., Ltd.). After attaching a clamp to the flask, the denture base material was immersed in 70°C water for 90 minutes and then in boiling water for 30 minutes to polymerize and harden. This was used as the test specimen (Figure 1). As shown in Figure 2, the test specimen was hooked onto the lingual surface of the artificial tooth in a dedicated jig, and the edge of the denture base material was fixed with a clamp. A tensile load was applied to the adhesive interface at a displacement rate of 1 mm / min to induce fracture at the bonded area of ​​the specimen. The tensile load was applied to the specimens using an Instron universal testing machine (Model: 5567A). Ten test specimens were tested for each curable composition, and the failure mode of each specimen was observed. A grade of A or B was used to evaluate the adhesion to the denture base material according to the following criteria. A grade of A or B indicated good adhesion to the denture base material. <Evaluation criteria> A: 10 or 9 out of 10 specimens failed cohesively B: Cohesive failure of 8 or 7 of 10 specimens C: Cohesive failure of 6 or less teeth out of 10

[0083] Tables 1 to 4 show the evaluation results of the curable compositions of the Examples and Comparative Examples.

[0084] Curable compositions (mass%) used in the examples and evaluation results [Table 1]

[0085] Curable compositions (mass%) used in the examples and evaluation results [Table 2]

[0086] Curable compositions (mass%) used in the examples and evaluation results [Table 3]

[0087] Curable compositions (mass%) used in comparative examples and evaluation results [Table 4]

[0088] As shown in Tables 1 to 4, the curable compositions of Examples 1 to 29 of the present invention had high surface hardness and compressive strength, and a large amount of compressive displacement, making them less susceptible to fracture. They also had excellent adhesion to denture base materials. On the other hand, the curable compositions of Comparative Examples 1 to 10 were inferior to the curable compositions of Examples 1 to 29 of the present invention in any of the properties of surface hardness, compressive strength, amount of compressive displacement (fracture resistance), or adhesion to denture base materials. [Industrial Applicability]

[0089] The composite resin teeth of the present invention can be used to fabricate dentures such as complete dentures and partial dentures.

Claims

1. A composite resin tooth having a single layer structure or a layer structure of two or more layers, The present invention includes a composite resin layer made of a polymerized and cured product of a curable composition containing a polymerizable monomer (A), an organic-inorganic composite filler (B), inorganic fine particles (C), and non-crosslinked polymer particles (D), the content of the non-crosslinked polymer particles (D) in the curable composition is in the range of 1% by mass or more and 5% by mass or less, A composite resin tooth characterized in that the average particle size of all of the inorganic particles (C) contained in the hardenable composition is 1 μm or less.

2. 2. The composite resin tooth according to claim 1, wherein the average particle size of the non-crosslinked polymer particles (D) is 5 μm or more and 50 μm or less.

3. The content of the inorganic fine particles (C) in the curable composition is in the range of 15% by mass or more and 35% by mass or less, and 3. A composite resin tooth according to claim 1, wherein the content of the inorganic filler (b-1) contained in the organic-inorganic composite filler (B) is in the range of 10% by mass or more and 35% by mass or less.

4. 3. The composite resin tooth according to claim 1, wherein the content of methyl methacrylate relative to the total amount of the polymerizable monomer (A) is 5% by mass or less.

5. 4. The composite resin tooth according to claim 3, wherein the content of methyl methacrylate relative to the total amount of the polymerizable monomer (A) is 5% by mass or less.

6. 6. The composite resin tooth according to claim 1, wherein the non-crosslinked polymer particles (D) comprise polymethyl methacrylate particles.

7. The composite resin tooth according to claim 3 , wherein the non-crosslinked polymer particles (D) include polymethyl methacrylate particles.

8. The composite resin tooth according to claim 4 , wherein the non-crosslinked polymer particles (D) include polymethyl methacrylate particles.

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