Dental adhesive composition

Abstract

The present invention provides a dental adhesive composition that can achieve both processability into a thin film of a cured product and high mechanical strength over a long period of time. This dental adhesive composition contains an acidic group-containing monomer (A), acidic group-free monomers (B), a polymerization initiator (C), water (D), a volatile organic solvent (E) and a filler (F), wherein: the acidic group-free monomers (B) include a monomer having 3 or more polymerizable groups per molecule (B-1), a hydrophobic monomer having 1 or 2 polymerizable groups per molecule (B-2), and a hydrophilic monomer having 1 or 2 polymerizable groups per molecule (B-3); the viscosity is less than 40 cps when measured at 30°C using a type B viscometer; and a cured product thereof has a water absorption rate of 4.0% or less.

Description

Dental adhesive composition

[0001] The present invention relates to a dental adhesive composition. More specifically, the present invention relates to a dental adhesive composition that can be cured to a thin film while maintaining high mechanical strength over a long period of time.

[0002] Adhesives are used for the repair of biological hard tissues in wet bodies (e.g., teeth, bones, etc.) Resin-based curable compositions containing radically polymerizable monomers, polymerization initiators, etc. are commonly used as adhesives for wet bodies.

[0003] Teeth that have lost their function due to caries or accidents are restored by fixing dental prostheses, such as metal or ceramic crown restorative materials called inlays or crowns, to the teeth. An adhesive called dental resin cement is used to fix the crown restorative materials to the teeth.

[0004] Dental treatments include the "direct restoration method," in which a dental restorative material made of composite resin is directly filled into the cavity, and the so-called "indirect restoration method," in which the above-mentioned dental crown restorative material is fixed to the tooth. In the indirect restoration method, the tooth preparation surface is generally sealed with a temporary sealing material or a temporary restoration is attached using a temporary adhesive until the dental prosthesis is fabricated.

[0005] In this context, a method has been proposed that aims to improve the adhesiveness of dental resin cement, improve the inner surface fit of restorations, and protect exposed dentin. This involves applying a dental adhesive to the cavity formation surface immediately after cavity formation and before impression taking to protect the exposed dentin and dental pulp, followed by the attachment of a temporary restoration such as a sealing material or temporary adhesive, and then improving the adhesiveness between the dental resin cement and dentin (hereinafter referred to as the resin coating method).

[0006] Dental adhesives used in resin coating methods must have a thin coating layer so as not to affect the shape of the prepared abutment tooth, and must have high adhesion to dentin and high mechanical strength to protect the exposed dentin. Regarding the shape of the prepared abutment tooth, adhesives tend to accumulate around the edges of the abutment tooth, and this effect is particularly pronounced when the viscosity of the adhesive is high. It has even been reported that changes in the shape of an abutment tooth coated by resin coating methods may affect the compatibility of the dental prosthesis with the abutment tooth (Non-Patent Document 1).

[0007] In the direct restoration method, where dental adhesives have been commonly used up to now, a thin adhesive layer is not required, and thinning is a characteristic required specifically for resin coating methods. Furthermore, since the mechanical strength of a coating layer generally depends on its thickness, the mechanical strength of a thinner coating layer is usually reduced.

[0008] In recent years, one-step adhesive systems using one-component dental adhesives (one-component bonding materials) that combine the functions of a self-etching primer and a bonding material have become widely used. One-component bonding materials generally contain an acidic monomer, a hydrophilic monomer, a crosslinkable monomer, or the like as a monomer component, and (meth)acrylate compounds are commonly used as the monomer component.

[0009] To enhance the mechanical strength of the cured product, Patent Document 1 proposes a bonding material containing a polymerizable monomer having a non-conjugated carbon chain with four or more carbon atoms bonded in succession, two or more polymerizable groups, and two or more hydroxyl groups, a polymerizable monomer having one or more polymerizable groups and one or more aromatic rings, 2-hydroxyethyl methacrylate, 10-methacryloyloxydecamethylene phosphate, water, ethanol, a polymerization accelerator, and a filler. Patent Document 2 proposes a dental adhesive containing a polymerizable monomer component including an acidic group-containing polymerizable monomer, water, a diaryliodonium salt compound, and a photopolymerization initiator consisting of a thioxanthone compound. Patent Document 3 proposes a dental adhesive composition containing an acidic group-containing polymerizable monomer, a water-soluble (meth)acrylate polymerizable monomer, water, a curing agent, and a crosslinkable polymerizable monomer having, in its molecule, at least three polymerizable groups and a hydrocarbon group in which at least six carbon atoms are bonded in succession in a linear or cyclic manner.

[0010] Japanese Patent Application Laid-Open No. 2008-260751 Japanese Patent Application Laid-Open No. 2007-223955 Japanese Patent Application Laid-Open No. 2005-179282

[0011] Japanese Society of Conservative Dentistry 2021 Autumn Academic Conference (155th) O1

[0012] It is conceivable to apply the dental bonding materials of Patent Documents 1 to 3 to resin coating applications. However, the inventors' investigations revealed that the cured products of Patent Documents 1 and 3 have high water absorption, and therefore there is room for improvement in order to satisfy the required properties for resin coating applications. Furthermore, the composition of Patent Document 2 has insufficient mechanical strength for application to resin coating applications.

[0013] As described above, in the prior art, there was room for improvement in dental adhesive compositions suitable for resin coating applications that combine the properties of being able to thin the cured product sufficiently to the extent that it does not affect the compatibility between the dental prosthesis and the abutment tooth, and having excellent mechanical strength over a long period of time so as to protect exposed dentin.

[0014] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a dental adhesive composition which can provide a thin cured product while maintaining high mechanical strength over a long period of time.

[0015] As a result of extensive research, the present inventors have discovered that a dental adhesive composition containing specific components and satisfying specific parameters can solve the above-mentioned problems, and after further research, have completed the present invention.

[0016] That is, the present invention encompasses the following inventions. [1] A dental adhesive composition comprising a monomer (A) having an acidic group, a monomer (B) not having an acidic group, a polymerization initiator (C), water (D), a volatile organic solvent (E), and a filler (F), wherein the monomer (B) not having an acidic group comprises a monomer (B-1) having three or more polymerizable groups per molecule, a hydrophobic monomer (B-2) having one or two polymerizable groups per molecule, and a hydrophilic monomer (B-3) having one or two polymerizable groups per molecule, wherein the viscosity measured with a Brookfield viscometer at 30°C is less than 40 cps, and the water absorption of the cured product is 4.0% or less. [2] The dental adhesive composition according to [1], wherein the monomer (B-1) having three or more polymerizable groups per molecule contains a hydrophobic compound. [3] The dental adhesive composition according to [1] or [2], wherein the monomer (B-1) having three or more polymerizable groups in one molecule contains a compound having a urethane bond. [4] The dental adhesive composition according to any one of [1] to [3], wherein the monomer (B-1) having three or more polymerizable groups in one molecule contains an aliphatic compound. [5] The dental adhesive composition according to any one of [1] to [4], wherein the content of the monomer (B-1) having three or more polymerizable groups in one molecule is 0.1 to 20 parts by mass per 100 parts by mass of the total monomer components. [6] The dental adhesive composition according to any one of [1] to [5], wherein the polymerizable group in the monomer (B-1) having three or more polymerizable groups in one molecule is a (meth)acryloyloxy group. [7] The dental adhesive composition according to any one of [1] to [6], wherein the polymerization initiator (C) comprises at least one selected from the group consisting of (bis)acylphosphine oxides, α-diketones, and coumarins. [8] The dental adhesive composition according to any one of [1] to [7], wherein the volatile organic solvent (E) comprises an alcohol solvent. [9] The dental adhesive composition according to any one of [1] to [8], wherein at least one of the monomer (B-1) having three or more polymerizable groups in one molecule, the hydrophobic monomer (B-2) having one or two polymerizable groups in one molecule, and the hydrophilic monomer (B-3) having one or two polymerizable groups in one molecule comprises a monomer having a (meth)acrylamide group.

[10] The dental adhesive composition according to [9], wherein the hydrophobic monomer (B-2) having one or two polymerizable groups per molecule contains a monomer having a (meth)acrylamide group.

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

[10] , wherein the monomer (A) having an acidic group contains a monomer having a phosphate group and one polymerizable group per molecule.

[12] The dental adhesive composition according to

[11] , wherein the content of the monomer having a phosphate group and one polymerizable group per molecule is 90 parts by mass or more per 100 parts by mass of the total amount of the monomer (A) having an acidic group contained in the dental adhesive composition.

[13] The dental adhesive composition according to any one of [1] to

[12] , wherein the monomer (B-1) having three or more polymerizable groups per molecule contains a hydrophobic compound, and all of the polymerizable groups of the hydrophobic compound are (meth)acryloyloxy groups.

[14] The dental bonding material according to any one of [1] to

[13] .

[15] The dental coating material according to any one of [1] to

[13] .

[0017] According to the present invention, a dental adhesive composition can be provided that can achieve both a thin film of the cured product and high mechanical strength over a long period of time. The dental adhesive composition of the present invention has excellent durability, so that even when used in the oral cavity for a long period of time, the dental adhesive composition can achieve both a thin film of the cured product and high mechanical strength over a long period of time. Furthermore, the dental adhesive composition of the present invention also has excellent adhesive strength to tooth tissue over a long period of time, and in resin coating applications, it can protect exposed dentin over a long period of time, making it suitable for use in indirect restorations. In resin coating applications requiring a thin film, the dental adhesive composition of the present invention maintains high mechanical strength over a long period of time even when the coating thickness is 12 μm or less (preferably 10 μm or less, more preferably less than 7 μm). Therefore, even if the layer of the cured product formed after an operation to volatilize the solvent component (such as air blowing) becomes thinner than expected due to variations in the layer thickness at different locations due to the degree of air blowing, the mechanical strength of the cured product does not decrease over a long period of time, making it particularly advantageous in resin coating applications in that strict operation is not required during use. Furthermore, the dental adhesive composition of the present invention has excellent adhesive strength to tooth structure and exhibits good cavity sealing properties, and therefore can be suitably used as a dental adhesive composition for general direct restorative methods.

[0018] The dental adhesive composition of the present invention comprises a monomer (A) having an acidic group, a monomer (B) not having an acidic group, a polymerization initiator (C), water (D), a volatile organic solvent (E), and a filler (F), wherein the monomer (B) not having an acidic group comprises a monomer (B-1) having three or more polymerizable groups in one molecule, a hydrophobic monomer (B-2) having one or two polymerizable groups in one molecule, and a hydrophilic monomer (B-3) having one or two polymerizable groups in one molecule, wherein the dental adhesive composition has a viscosity of less than 40 cps at 30°C as measured with a Brookfield viscometer, and a water absorption rate of the cured product of 4.0% or less.

[0019] In this specification, "(meth)acrylic" is a general term for methacrylic and acrylic, and the same applies to similar expressions (such as "(meth)acrylic acid" and "(meth)acrylonitrile"). In this specification, "monofunctional monomer" means a monomer having one polymerizable group in one molecule. In this specification, the upper and lower limit values ​​of the numerical ranges (content of each component, values ​​calculated from each component, and each physical property) can be combined as appropriate. Furthermore, in this specification, each embodiment can be combined as appropriate, or other modifications can be made.

[0020] In general, in a composition, a polyfunctional monomer such as the monomer (B-1) having three or more polymerizable groups per molecule has the effect of increasing mechanical strength, but the increased curing rate also leads to the problem of increased polymerization shrinkage. Furthermore, as the content of the polyfunctional monomer increases in the entire composition, the content of the monofunctional monomer, which has permeability to tooth tissue, decreases relatively, resulting in a problem of decreased permeability of the composition to tooth tissue and a decrease in adhesive strength to tooth tissue. Furthermore, the present inventors have discovered that when the content of the polyfunctional monomer such as the monomer (B-1) having three or more polymerizable groups per molecule is increased in the entire composition, without blending a hydrophobic monomer having one or two polymerizable groups per molecule, the hydrophobicity cannot be sufficiently increased to the level required for resin coating applications, and as a result, the water absorption of the cured product cannot be sufficiently reduced, and in resin coating applications, it is not possible to achieve both a thin coating layer and high mechanical strength. Furthermore, in the resin coating method, it is difficult to achieve both high mechanical strength and thin coating layer thickness, making it even more difficult to produce a dental adhesive composition in which the thin, cured product maintains high mechanical strength for a long period of time. As described above, it has been found that simply increasing the content of a polyfunctional monomer such as the monomer (B-1) having three or more polymerizable groups in one molecule makes it impossible to simultaneously protect the dentin exposed by cavity formation for a long period of time and thin the coating layer, which is the cured product of the dental adhesive composition and is intended not to affect the shape of the formed abutment tooth.

[0021] In contrast, the reason why the dental adhesive composition of the present invention can achieve both thin film formation of the cured product and high mechanical strength over a long period of time is unclear, but is presumed to be as follows. In the present invention, the monomer (A) having an acidic group, the monomer (B) not having an acidic group (including a monomer (B-1) having three or more polymerizable groups per molecule, a hydrophobic monomer (B-2) having one or two polymerizable groups per molecule, and a hydrophilic monomer (B-3) having one or two polymerizable groups per molecule), the polymerization initiator (C), water (D), the volatile organic solvent (E), and the filler (F) are composed of appropriate types and in appropriate proportions, so that these components act together to reduce the viscosity of the dental adhesive composition. This makes it possible to form a thin film of the cured product. Furthermore, it is presumed that the combination of high curability and moderate hydrophobicity of the composition makes it possible to suppress the occurrence of components or their action mechanisms that reduce the mechanical strength of the cured product, thereby achieving high mechanical strength over a long period of time.

[0022] The dental adhesive composition of the present invention has a viscosity of less than 40 cps at 30°C. A viscosity within this range allows the cured product to be made thin, thereby suppressing the effect on the compatibility of the dental prosthesis and the abutment tooth. Furthermore, by having the viscosity within this range, the bond layer formed can be made very thin, and further, in combination with the water absorption rate of the cured product being a predetermined rate, these two factors act together to suppress a decrease in mechanical strength despite the bond layer being made very thin, allowing the bond layer to exhibit high mechanical strength over a long period of time.

[0023] The viscosity can be adjusted by appropriately combining the type, blending ratio and viscosity of the monomer, the type and content of the filler, the content of water, the type and content of the volatile organic solvent, and the like.

[0024] The adjustment of viscosity will be described below. Generally, the greater the number of polymerizable groups in a monomer, the higher the viscosity. Also, if a monomer contains a moiety that has intramolecular and intermolecular interactions, the viscosity of the monomer will be higher. For example, if a monomer contains a hydroxyl group, NH ２The viscosity of the monomer increases when the monomer contains a functional group having hydrogen bonding properties, such as a hydroxyl group; the viscosity also increases when the monomer has ionic bonding properties; and the viscosity also increases when the monomer contains an aromatic ring. The type, blending ratio, and viscosity of the monomer can be appropriately adjusted, taking into consideration the mechanical strength of the cured product, adhesion to tooth structure, and the like. In the present invention, the viscosity can be adjusted to a desired range by using a high-viscosity monomer (B-1) having three or more polymerizable groups per molecule in combination with a monomer having one or two polymerizable groups per molecule (a hydrophobic monomer (B-2) having one or two polymerizable groups per molecule, or a hydrophilic monomer (B-3) having one or two polymerizable groups per molecule), and further combining it with a filler (F) and a solvent (water (D), a volatile organic solvent (E)).

[0025] The smaller the particle size of the filler, the greater the thickening effect of the dental adhesive composition. Furthermore, the thickening effect is affected by the presence or absence of surface treatment. For example, when a filler that has not been surface-treated is used, the hydroxyl groups present on the filler surface interact with other components in the dental adhesive composition, resulting in a greater thickening effect. The type and content of the filler can be appropriately adjusted, taking into account the mechanical strength of the cured product, adhesion to tooth structure, and the like.

[0026] The higher the content of water and volatile organic solvent, the lower the viscosity of the dental adhesive composition tends to be. When applying the dental adhesive composition to a tooth, water and volatile organic solvent inhibit curing and reduce the mechanical strength of the cured product, so they must be volatilized by air blowing. Therefore, it is necessary to adjust the content of water and volatile organic solvent to an appropriate level. The content of water and the type and content of volatile organic solvent can be appropriately adjusted taking into account properties such as the mechanical strength of the cured product and adhesion to tooth tissue.

[0027] The viscosity at 30°C as measured by a Brookfield viscometer is less than 40 cps, preferably 5 to 40 cps, more preferably 10 to 40 cps, even more preferably 15 to 35 cps, and particularly preferably 20 to 30 cps, from the viewpoint of thinning of the cured product and mechanical strength. The viscosity is measured by the method described in the Examples.

[0028] The dental adhesive composition of the present invention has a water absorption rate of 4.0% or less after curing. A water absorption rate within this range allows for thin coating layers in resin coating applications and provides excellent mechanical strength. A water absorption rate within this range allows for the cured product to have excellent adhesion to tooth structure and mechanical strength, which, combined with a predetermined viscosity, act as an integrated whole, resulting in not only excellent mechanical strength but also excellent durability of the cured product, which maintains these properties (adhesion to tooth structure and mechanical strength) for a long period of time.

[0029] The water absorption of the cured product can be adjusted by the type and blending ratio of the monomer, the type and amount of the polymerization initiator, the type, amount and ratio of the polymerization accelerator to the polymerization initiator, the type, particle size and content of the filler, the amount of water, and the type and amount of the volatile organic solvent. Of the above, adjusting the type and blending ratio of the monomer in particular makes it easier to obtain a desired water absorption. Adjusting other components such as the polymerization initiator within the ranges described in this specification makes it even easier to adjust the desired water absorption.

[0030] The adjustment of water absorption is described below. Generally, the more hydrophilic functional groups (e.g., hydroxyl groups, ether bonds, and amines) a monomer has, the higher its water absorption, while the less these functional groups it has, the lower its water absorption. The larger the particle size of a filler, the smaller its specific surface area, resulting in less water adhering to the surface, and therefore a lower water absorption. On the other hand, the smaller the particle size, the more water adhering to the surface, resulting in a higher water absorption. Surface treatment of a filler can enhance the hydrophobicity of the surface, lowering its water absorption. The more hydrophobic the surface, the lower the water absorption. To increase the hydrophobicity of a filler, a method can be considered in which a dehydration condensation reaction is promoted by using a filler with a large number of hydroxyl groups on its surface (e.g., an inorganic filler primarily composed of silica) to promote the surface treatment. Alternatively, the water absorption can be reduced by using a filler type that is already highly hydrophobic.

[0031] When comparing the effect of fillers and hydrophilic monomers on the increase in water absorption, the effect of hydrophilic monomers is greater. Therefore, the higher the filler content and the lower the hydrophilic monomer content, the lower the water absorption rate, and the lower the filler content and the higher the hydrophilic monomer content, the higher the water absorption rate. In addition, organic fillers generally tend to have higher water absorption rates than inorganic fillers and organic-inorganic composite fillers.

[0032] The water absorption of the cured product of the dental adhesive composition of the present invention is 4.0% or less, preferably 3.5% or less, more preferably 3.0% or less, even more preferably 2.5% or less, and particularly preferably less than 2.3%, from the viewpoint of the mechanical strength of the cured product, adhesion to tooth structure, and their durability. If the water absorption exceeds 4.0%, the cured product may not have sufficient mechanical strength and adhesion to tooth structure over a long period of time. The method for measuring the water absorption is as described in the Examples.

[0033] Furthermore, in terms of being able to form a thin film in a resin coating method and being able to easily obtain high mechanical strength over a long period of time, the dental adhesive composition of the present invention preferably has a water absorption rate of 7.5% or less, more preferably 7.0% or less, even more preferably 6.5% or less, and particularly preferably less than 6.0%, of the cured product after immersion in distilled water at 37°C for 7 days. The method for measuring the water absorption rate of the cured product after immersion in distilled water at 37°C for 7 days is as described in the Examples.

[0034] Each component used in the dental adhesive composition of the present invention will be explained below.

[0035] <Monomer (A) Having an Acidic Group> From the viewpoint of adhesion to tooth structure, a monomer (A) having an acidic group is essential for the dental adhesive composition. By blending a monomer (A) having an acidic group, excellent adhesion to tooth structure can be achieved. A radically polymerizable monomer is preferably used for the dental adhesive composition. Specific examples of the radically polymerizable monomer in the monomer (A) having an acidic group include (meth)acrylate monomers, (meth)acrylamide monomers, esters of α-cyanoacrylic acid, α-halogenated acrylic acid, crotonic acid, cinnamic acid, sorbic acid, maleic acid, itaconic acid, etc., vinyl esters, vinyl ethers, mono-N-vinyl derivatives, styrene derivatives, etc. Among these, from the viewpoint of curability, (meth)acrylate monomers and (meth)acrylamide monomers in which the polymerizable group is a (meth)acryloyloxy group or a (meth)acrylamide group are preferred. The monomer (A) having an acidic group is preferably a monomer having one or two polymerizable groups in one molecule (monofunctional monomer or bifunctional polymer), and more preferably a monomer having one polymerizable group in one molecule, because it has excellent adhesion to tooth structure (especially dentin) and is easy to prevent the dental adhesive composition from becoming too viscous when combined with other monomers.

[0036] The monomer (A) having an acidic group used in the present invention includes, for example, a monomer having at least one acidic group such as a phosphoric acid group, a pyrophosphate group, a thiophosphate group, a phosphonic acid group, a carboxylic acid group, or a sulfonic acid group. The monomer (A) having an acidic group can be used alone or in appropriate combination of two or more. Specific examples of the monomer (A) having an acidic group are shown below.

[0037] Examples of the monomer having a phosphate group include 2-(meth)acryloyloxyethyl dihydrogen phosphate, 3-(meth)acryloyloxypropyl dihydrogen phosphate, 4-(meth)acryloyloxybutyl dihydrogen phosphate, 5-(meth)acryloyloxypentyl dihydrogen phosphate, 6-(meth)acryloyloxyhexyl dihydrogen phosphate, 7-(meth)acryloyloxyheptyl dihydrogen phosphate, and 8-(meth)acryloyloxyoctyl dihydrogen phosphate. acrylate, 9-(meth)acryloyloxynonyl dihydrogen phosphate, 10-(meth)acryloyloxydecyl dihydrogen phosphate, 11-(meth)acryloyloxyundecyl dihydrogen phosphate, 12-(meth)acryloyloxydodecyl dihydrogen phosphate, 16-(meth)acryloyloxyhexadecyl dihydrogen phosphate, 20-(meth)acryloyloxyicosyl dihydrogen phosphate, 2-(meth)acryloyloxyethyl phenyl hydrogen phosphate, Monofunctional monomers such as 2-(meth)acryloyloxyethyl-(2-bromoethyl)hydrogenphosphate, 2-methacryloyloxyethyl-(4-methoxyphenyl)hydrogenphosphate, and 2-methacryloyloxypropyl-(4-methoxyphenyl)hydrogenphosphate; bis[2-(meth)acryloyloxyethyl]hydrogenphosphate, bis[4-(meth)acryloyloxybutyl]hydrogenphosphate, bis[6-(meth)acryloyloxyhexyl]hydrogenphosphate, bis[ Examples of the difunctional monomer include bifunctional monomers such as bis[8-(meth)acryloyloxyoctyl]hydrogenphosphate, bis[9-(meth)acryloyloxynonyl]hydrogenphosphate, bis[10-(meth)acryloyloxydecyl]hydrogenphosphate, 1,3-glycerol di(meth)acrylate phosphate (also known as 1,3-di(meth)acryloyloxypropyl dihydrogenphosphate), and acid chlorides, alkali metal salts, and amine salts thereof, and a monomer having an alkylene group having 6 to 12 carbon atoms and a divalent phosphate group is preferred.A preferred embodiment includes a dental adhesive composition in which the monomer (A) having an acidic group contains a monomer having a phosphate group and one polymerizable group per molecule. Another preferred embodiment includes a dental adhesive composition in which the content of the monomer having a phosphate group and one polymerizable group per molecule is 90 parts by mass or more per 100 parts by mass of the total monomers (A) having an acidic group contained in the dental adhesive composition. In the above embodiment, the content of the monomer having a phosphate group and one polymerizable group per molecule is preferably 92 parts by mass or more, more preferably 95 parts by mass or more, even more preferably 98 parts by mass or more, and particularly preferably 100 parts by mass per 100 parts by mass of the total monomers (A) having an acidic group. Another preferred embodiment includes a dental adhesive composition in which the monomer (A) having an acidic group contains a monomer having an alkylene group having 6 to 12 carbon atoms and a divalent phosphate group. In any of the preferred embodiments described above, the polymerizable group possessed by the monomer is preferably a (meth)acryloyloxy group.

[0038] Examples of the monomer having a pyrophosphate group include bis[2-(meth)acryloyloxyethyl] pyrophosphate, bis[4-(meth)acryloyloxybutyl] pyrophosphate, bis[6-(meth)acryloyloxyhexyl] pyrophosphate, bis[8-(meth)acryloyloxyoctyl] pyrophosphate, bis[10-(meth)acryloyloxydecyl] pyrophosphate, and acid chlorides, alkali metal salts, and amine salts thereof.

[0039] Examples of the monomer having a thiophosphate group include 2-(meth)acryloyloxyethyl dihydrogenthiophosphate, 3-(meth)acryloyloxypropyl dihydrogenthiophosphate, 4-(meth)acryloyloxybutyl dihydrogenthiophosphate, 5-(meth)acryloyloxypentyl dihydrogenthiophosphate, 6-(meth)acryloyloxyhexyl dihydrogenthiophosphate, 7-(meth)acryloyloxyheptyl dihydrogenthiophosphate, and 8-(meth)acryloyloxyoctyl dihydrogenthiophosphate. phosphate, 9-(meth)acryloyloxynonyl dihydrogen thiophosphate, 10-(meth)acryloyloxydecyl dihydrogen thiophosphate, 11-(meth)acryloyloxyundecyl dihydrogen thiophosphate, 12-(meth)acryloyloxydodecyl dihydrogen thiophosphate, 16-(meth)acryloyloxyhexadecyl dihydrogen thiophosphate, 20-(meth)acryloyloxyicosyl dihydrogen thiophosphate, and acid chlorides, alkali metal salts, and ammonium salts thereof.

[0040] Examples of the monomer having a phosphonic acid group include 2-(meth)acryloyloxyethyl phenylphosphonate, 5-(meth)acryloyloxypentyl-3-phosphonopropionate, 6-(meth)acryloyloxyhexyl-3-phosphonopropionate, 10-(meth)acryloyloxydecyl-3-phosphonopropionate, 6-(meth)acryloyloxyhexyl-3-phosphonoacetate, 10-(meth)acryloyloxydecyl-3-phosphonoacetate, and acid chlorides, alkali metal salts, and ammonium salts thereof.

[0041] Examples of the monomer having a carboxylic acid group include a monofunctional (meth)acrylic acid ester having one carboxyl group or an acid anhydride group thereof in one molecule, and a monofunctional (meth)acrylic acid ester having multiple carboxyl groups or acid anhydride groups thereof in one molecule.

[0042] Examples of monofunctional monomers having one carboxyl group or an acid anhydride group thereof in one molecule include (meth)acrylic acid, N-(meth)acryloylglycine, N-(meth)acryloylaspartic acid, 2-(meth)acryloyloxyethyl hydrogen succinate, 2-(meth)acryloyloxyethyl hydrogen phthalate, 2-(meth)acryloyloxyethyl hydrogen maleate, O-(meth)acryloyltyrosine, N-(meth)acryloyltyrosine, Examples of the acryloyloxybenzoic acid include acryloylphenylalanine, N-(meth)acryloyl-p-aminobenzoic acid, N-(meth)acryloyl-o-aminobenzoic acid, 2-(meth)acryloyloxybenzoic acid, 3-(meth)acryloyloxybenzoic acid, 4-(meth)acryloyloxybenzoic acid, N-(meth)acryloyl-5-aminosalicylic acid, and N-(meth)acryloyl-4-aminosalicylic acid, as well as compounds in which the carboxyl group of these compounds has been converted to an acid anhydride group.

[0043] Examples of monofunctional monomers having a plurality of carboxyl groups or acid anhydride groups thereof in one molecule include 6-(meth)acryloyloxyhexane-1,1-dicarboxylic acid, 9-(meth)acryloyloxynonane-1,1-dicarboxylic acid, 10-(meth)acryloyloxydecane-1,1-dicarboxylic acid, 11-(meth)acryloyloxyundecane-1,1-dicarboxylic acid, 12-(meth)acryloyloxydodecane-1,1-dicarboxylic acid, 13-(meth)acryloyloxytridecane-1,1-dicarboxylic acid, 4-(meth)acryloyloxyethyl trimellitate, 4-(meth)acryloyloxyethyl trimellitic anhydride ... butyl trimellitate, 4-(meth)acryloyloxyhexyl trimellitate, 4-(meth)acryloyloxydecyl trimellitate, 2-(meth)acryloyloxyethyl-3'-(meth)acryloyloxy-2'-(3,4-dicarboxybenzoyloxy)propyl succinate, 6-(meth)acryloyloxyethylnaphthalene-1,2,6-tricarboxylic anhydride, 6-(meth)acryloyloxyethylnaphthalene-2,3,6-tricarboxylic anhydride, 4-(meth)acryloyloxyethylcarbonylpropionoyl-1,8-naphthalic anhydride, 4-(meth)acryloyloxyethylnaphthalene-1,8-tricarboxylic anhydride, and the like.

[0044] Examples of the monomer having a sulfonic acid group include 2-sulfoethyl (meth)acrylate.

[0045] Furthermore, among the above-mentioned monomers (A) having an acidic group, from the viewpoint of providing a dental adhesive composition with good adhesive strength to tooth structure, it is preferable to contain a monomer having a phosphate group or a monomer having a carboxylic acid group, and examples thereof include 2-(meth)acryloyloxyethyl dihydrogen phosphate, 3-(meth)acryloyloxypropyl dihydrogen phosphate, 4-(meth)acryloyloxybutyl dihydrogen phosphate, 5-(meth)acryloyloxypentyl dihydrogen phosphate, 6-(meth)acryloyloxyhexyl dihydrogen phosphate, 7-(meth)acryloyloxyheptyl dihydrogen phosphate, 8-(meth)acryloyloxyoctyl dihydrogen phosphate, 9-(meth)acryloyloxyoctyl dihydrogen phosphate, 10-(meth)acryloyloxyoctyl dihydrogen phosphate, 11-(meth)acryloyloxyoctyl dihydrogen phosphate, 12-(meth)acryloyloxyoctyl dihydrogen phosphate, 13-(meth)acryloyloxyoctyl dihydrogen phosphate, 14-(meth)acryloyloxyoctyl dihydrogen phosphate, 15-(meth)acryloyloxyoctyl dihydrogen phosphate, 16-(meth)acryloyloxyoctyl dihydrogen phosphate, 17-(meth)acryloyloxyoctyl dihydrogen phosphate, 18-(meth)acryloyloxyoctyl dihydrogen phosphate, 19-(meth)acryloyloxyoctyl dihydrogen phosphate, 20-(meth)acryloyloxyoctyl dihydrogen phosphate, 21-(meth)acryloyloxyoctyl dihydrogen phosphate, 22-(meth)acryloyloxyoctyl dihydrogen phosphate, 23-(meth)acryloyloxyoctyl dihydrogen phosphate, 24- ethyl dihydrogen phosphate, 9-(meth)acryloyloxynonyl dihydrogen phosphate, 10-(meth)acryloyloxydecyl dihydrogen phosphate, 11-(meth)acryloyloxyundecyl dihydrogen phosphate, 12-(meth)acryloyloxydodecyl dihydrogen phosphate, 16-(meth)acryloyloxyhexadecyl dihydrogen phosphate, 20-(meth)acryloyloxyicosyl dihydrogen phosphate, 4-(meth)acryloyloxyethyl trimellitate anhydride, 4-(meth)acryloyloxyethyl trimellitate, 11-(meth)acryloyloxyundecane-1,1-Dicarboxylic acid and a mixture of 2-methacryloyloxyethyl dihydrogen phosphate and bis(2-methacryloyloxyethyl)hydrogen phosphate are more preferred, and 8-(meth)acryloyloxyoctyl dihydrogen phosphate, 9-(meth)acryloyloxynonyl dihydrogen phosphate, 10-(meth)acryloyloxydecyl dihydrogen phosphate, 11-(meth)acryloyloxyundecyl dihydrogen phosphate, More preferred are 12-(meth)acryloyloxydodecyl dihydrogen phosphate, 16-(meth)acryloyloxyhexadecyl dihydrogen phosphate, and 20-(meth)acryloyloxyicosyl dihydrogen phosphate, and 10-(meth)acryloyloxydecyl dihydrogen phosphate is particularly preferred from the viewpoints of easily preventing the dental adhesive composition from becoming too viscous and of the balance between adhesive strength to tooth substrate and curability.

[0046] The content of the monomer (A) having an acidic group in the dental adhesive composition is preferably 1 to 50 mass %, more preferably 1 to 30 mass %, and even more preferably 3 to 20 mass %, of the total mass of the dental adhesive composition, from the viewpoint of easily suppressing an increase in viscosity of the dental adhesive composition when combined with other monomers, and from the viewpoint of adhesiveness to tooth structure.

[0047] <Monomer (B) having no acidic group> Examples of the monomer (B) having no acidic group in the present invention include a monomer (B-1) having three or more polymerizable groups in one molecule, a hydrophobic monomer (B-2) having one or two polymerizable groups in one molecule, and a hydrophilic monomer (B-3) having one or two polymerizable groups in one molecule.

[0048] Monomer (B-1) Having Three or More Polymerizable Groups in One Molecule A monomer (B-1) having three or more polymerizable groups in one molecule (hereinafter sometimes simply referred to as "polyfunctional monomer (B-1)") is used in the dental adhesive composition of the present invention to achieve both thin film formation and high mechanical strength of the cured product. Examples of the polymerizable group include a vinyl group, a (meth)acryloyloxy group, and a (meth)acrylamide group. From the viewpoint of ease of radical polymerization, a (meth)acryloyloxy group and / or a (meth)acrylamide group is preferred, and from the viewpoint of adhesion to dentin, a (meth)acrylamide group is preferred. One type of polyfunctional monomer (B-1) may be used alone, or two or more types may be used in combination.

[0049] The number of polymerizable groups contained in the polyfunctional monomer (B-1) is 3 or more, and may be 4 or more. The upper limit of the number of polymerizable groups is not particularly limited, but may be 10 or less, or 6 or less.

[0050] The polyfunctional monomer (B-1) preferably contains a hydrophobic compound, as this can sufficiently enhance hydrophobicity and further reduce the water absorption rate of the cured product. The hydrophobic compound is preferably a compound having a solubility of less than 10% by mass in water at 25°C. The hydrophobicity of the hydrophobic compound can be adjusted by a hydrophilic group. Examples of the hydrophilic group include at least one selected from the group consisting of a hydroxyl group, an oxymethylene group, an oxyethylene group, an oxypropylene group, and an amide group. The hydrophobic compound is preferably a compound that does not have a hydrophilic group, and more preferably a compound that does not have a hydroxyl group. A preferred embodiment includes a dental adhesive composition in which the hydrophobic compound contains a compound having one or less hydroxyl groups. Another preferred embodiment includes a dental adhesive composition in which all polymerizable groups in the hydrophobic compound are (meth)acryloyloxy groups.

[0051] From the viewpoint of mechanical strength, the polyfunctional monomer (B-1) preferably contains a compound having a urethane bond. From the viewpoint of viscosity, the polyfunctional monomer (B-1) preferably contains an aliphatic compound, and from the viewpoint of mechanical strength, it is more preferable that the polyfunctional monomer (B-1) contains an aliphatic compound having a urethane bond.

[0052] Examples of the polyfunctional monomer (B-1) include trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolmethane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol poly(meth)acrylate, ethoxylated dipentaerythritol poly(meth)acrylate, ditrimethylol Examples of the acrylate copolymer include diacryloylpropane tetramethacrylate, ethoxylated glycerin triacrylate, tris-2-(meth)acryloyloxyethyl)isocyanurate, N,N-(2,2,4-trimethylhexamethylene)bis[2-(aminocarboxy)propane-1,3-diol]tetra(meth)acrylate, 1,7-diacryloyloxy-2,2,6,6-tetra(meth)acryloyloxymethyl-4-oxaheptane, N,N',N''-triacryloyldiethylenetriamine, N,N',N'',N'''-tetraacryloyltriethylenetetramine, and compounds represented by the following formulas (1) to (3). Among these, trimethylolpropane tri(meth)acrylate, N,N-(2,2,4-trimethylhexamethylene)bis[2-(aminocarboxy)propane-1,3-diol]tetramethacrylate, ditrimethylolpropane tetramethacrylate, and N,N',N'',N'''-tetraacryloyltriethylenetetramine are preferred from the viewpoint of mechanical strength.

[0053]

[0054]

[0055]

[0056] The content of the monomer (B-1) having three or more polymerizable groups per molecule in the dental adhesive composition of the present invention is preferably 0.1 to 20% by mass, more preferably 0.5 to 15% by mass, even more preferably 1 to 10% by mass, and particularly preferably 2 to 8% by mass, based on the total mass of the dental adhesive composition, from the viewpoints of long-term mechanical strength, viscosity, and adhesion to tooth structure. By having the content of the monomer (B-1) having three or more polymerizable groups per molecule be 20% by mass or less, when combined with other components such as a hydrophobic monomer (B-2) having one or two polymerizable groups per molecule, hydrophobicity can be sufficiently enhanced, the desired water absorption of the cured product can be easily obtained, and when combined with a predetermined viscosity, both a thin coating layer and excellent long-term mechanical strength can be achieved in a resin coating method. In one embodiment, the content of the monomer (B-1) having three or more polymerizable groups per molecule is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, even more preferably 1 to 10 parts by mass, and particularly preferably 2 to 8 parts by mass, relative to 100 parts by mass of all the monomer components of the dental adhesive composition. When the content of the monomer (B-1) having three or more polymerizable groups per molecule is 20 parts by mass or less relative to 100 parts by mass of all the monomer components of the dental adhesive composition, hydrophobicity can be sufficiently enhanced when combined with other components such as a hydrophobic monomer (B-2) having one or two polymerizable groups per molecule, and the desired water absorption rate of the cured product can be easily obtained. When combined with a predetermined viscosity, a thin coating layer can be formed in a resin coating method, while maintaining excellent mechanical strength over a long period of time.

[0057] Hydrophobic Monomer (B-2) having one or two polymerizable groups per molecule (hereinafter, may be simply referred to as "hydrophobic monomer (B-2)") means a monomer that does not have an acidic group and has a solubility of less than 10% by mass in water at 25° C. As the hydrophobic monomer (B-2), one having a solubility of less than 5% by mass in water at 25° C. is preferred, and one having a solubility of less than 1% by mass is more preferred.

[0058] The hydrophobic monomer (B-2) can improve the mechanical strength and durability (adhesion strength to tooth structure, mechanical strength) of the cured product of the dental adhesive composition, and can reduce the water absorption rate. The hydrophobic monomer (B-2) is preferably a radically polymerizable monomer having a polymerizable group but no acidic group. Examples of the polymerizable group possessed by the hydrophobic monomer (B-2) include a vinyl group, a (meth)acryloyloxy group, and a (meth)acrylamide group. From the viewpoint of ease of radical polymerization, a (meth)acryloyloxy group and / or a (meth)acrylamide group is preferred, and from the viewpoint of adhesion to dentin, a (meth)acrylamide group is preferred. From the viewpoints of water absorption rate, long-term mechanical strength, and adhesion to dentin, the hydrophobic monomer (B-2) more preferably contains a compound having a (meth)acrylamide group and a (meth)acryloyloxy group, and even more preferably contains a compound having an acrylamide group and a methacryloyloxy group. The hydrophobic monomer (B-2) may be used alone or in combination of two or more kinds.

[0059] Examples of the hydrophobic monomer (B-2) include a monofunctional monomer having one polymerizable group per molecule and a bifunctional monomer having two polymerizable groups per molecule. Examples of the bifunctional monomer having one polymerizable group per molecule include an aromatic compound-based bifunctional hydrophobic monomer and an aliphatic compound-based bifunctional hydrophobic monomer.

[0060] Among the hydrophobic monomers (B-2), examples of the monofunctional monomer include aliphatic compound-based monofunctional (meth)acrylate monomers such as n-stearyl methacrylate; aliphatic compound-based monofunctional (meth)acrylate monomers having an ether bond such as butoxydiethylene glycol methacrylate and methoxypolyethylene glycol methacrylate (average number of moles of oxyethylene groups added: 9); alicyclic compound-based monofunctional (meth)acrylate monomers such as cyclohexyl methacrylate, isobornyl methacrylate and dicyclopentanyl methacrylate; monofunctional (meth)acrylate monomers having an aromatic ring group such as 2-phenoxyethyl methacrylate and phenoxybenzyl methacrylate; and monofunctional (meth)acrylate monomers having a heterocyclic group (for example, a cyclic ether group) such as tetrahydrofurfuryl methacrylate.

[0061] The monofunctional (meth)acrylate monomer having an aromatic ring group is preferably one having one or two phenyl groups.

[0062] The monofunctional (meth)acrylate monomer having a heterocyclic group is preferably one having one or two heterocyclic groups (for example, a cyclic ether group).

[0063] Among the monofunctional monomers, tetrahydrofurfuryl methacrylate (commonly known as THF-MA), benzyl methacrylate (commonly known as BEMA), phenoxybenzyl methacrylate (commonly known as POB-MA), and 2-phenoxyethyl methacrylate (commonly known as PEMA) are preferred from the viewpoints of mechanical strength and viscosity.

[0064] Examples of aromatic compound-based bifunctional hydrophobic monomers include 2,2-bis((meth)acryloyloxyphenyl)propane, 2,2-bis[4-(3-(meth)acryloyloxy-2-hydroxypropoxy)phenyl]propane, 2,2-bis(4-(meth)acryloyloxyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxypolyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxydiethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxytriethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxytetraethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxypentaethoxyphenyl)propane, 2-(4-(meth)acryloyloxydipropoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxydiethoxyphenyl)-2-(4-(meth)acryloyloxyethoxyphenyl)propane, 2-(4-(meth)acryloyloxydiethoxyphenyl)-2-(4-(meth)acryloyloxytriethoxyphenyl)propane, 2-(4-(meth)acryloyloxydipropoxyphenyl)-2-(4-(meth)acryloyloxytriethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxypropoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxyisopropoxyphenyl)propane, and the like. Among these, from the viewpoints of adhesion to tooth structure and mechanical strength, 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl]propane (commonly known as "Bis-GMA"), 2,2-bis(4-(meth)acryloyloxyethoxyphenyl)propane, 2,2-bis(4-methacryloyloxypolyethoxyphenyl)propane (average number of moles of ethoxy groups added: 2.6, commonly known as "D-2.6E"), 2,2-bis(4-(meth)acryloyloxydiethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxytriethoxyphenyl)propane, 2,2-bis(4-(meth)acryloyloxytetraethoxyphenyl)propane, and 2,2-bis(4-(meth)acryloyloxypentaethoxyphenyl)propane are preferred.

[0065] Examples of the aliphatic compound-based bifunctional hydrophobic monomer include glycerol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, methacryloyloxyethyl)acrylate, 1,10-decanediol di(meth)acrylate, 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)di(meth)acrylate, N-methacryloyloxyethyl acrylamide (commonly known as "MAEA"), N-methacryloyloxypropyl acrylamide, N-methacryloyloxybutyl acrylamide, N-(1-ethyl-(2-methacryloyloxy)ethyl)acrylamide, N-(2-(2-methacryloyloxyethoxy)ethyl)acrylamide, and the like. Among these, from the viewpoints of mechanical strength and handleability, triethylene glycol diacrylate, triethylene glycol dimethacrylate (commonly known as "3G"), neopentyl glycol dimethacrylate (commonly known as "NPG"), 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)dimethacrylate (commonly known as "UDMA"), and 1,10-decanediol dimethacrylate (commonly known as "DD") are preferred. From the viewpoint of polymerization shrinkage stress, UDMA and DD are preferred. From the viewpoint of adhesion to tooth structure, particularly dentin, N-methacryloyloxypropylacrylamide (MAEA) is preferred.

[0066] Among the hydrophobic monomers (B-2), aromatic bifunctional hydrophobic monomers and aliphatic bifunctional hydrophobic monomers are preferably used from the viewpoints of water absorption, mechanical strength, solubility in water, and handleability. Bis-GMA and D-2.6E are preferred as aromatic bifunctional monomers. 3G, neopentyl glycol di(meth)acrylate, UDMA, DD, and MAEA are preferred as aliphatic bifunctional monomers.

[0067] The content of the hydrophobic monomer (B-2) in the dental adhesive composition is preferably 5 to 60 mass %, more preferably 10 to 50 mass %, even more preferably 12 to 45 mass %, and particularly preferably 15 to 40 mass %, based on the total mass of the dental adhesive composition. When the content of the hydrophobic monomer (B-2) is equal to or less than the upper limit described below, it is easy to prevent the wettability of the dental adhesive composition to tooth structure from decreasing and the adhesive strength from decreasing, and when the content is equal to or more than the lower limit described above, it is easy to obtain the desired mechanical strength and water absorption of the cured product.

[0068] Hydrophilic Monomer (B-3) having one or two polymerizable groups per molecule (hereinafter, sometimes simply referred to as "hydrophilic monomer (B-3)") means a monomer that does not have an acidic group and has a solubility of 10% by mass or more in water at 25° C. As the hydrophilic monomer (B-3), one having a solubility of 30% by mass or more in water at 25° C. is preferred, and one that can be dissolved in water at any ratio at 25° C. is more preferred.

[0069] The hydrophilic monomer (B-3) can improve the wettability of the dental adhesive composition to tooth tissue and the permeability into tooth tissue (enamel / dentin), thereby improving the adhesive strength to tooth tissue. The hydrophilic monomer (B-3) is preferably a radically polymerizable monomer having a polymerizable group but no acidic group. Examples of the polymerizable group possessed by the hydrophilic monomer (B-3) include a vinyl group, a (meth)acryloyloxy group, and a (meth)acrylamide group. From the viewpoint of ease of radical polymerization, a (meth)acryloyloxy group and / or a (meth)acrylamide group is preferred, and from the viewpoint of adhesiveness to dentin, a (meth)acrylamide group is preferred. The hydrophilic monomer (B-3) may be used alone or in combination of two or more types.

[0070] The hydrophilic monomer (B-3) is preferably one having a hydrophilic group such as a hydroxyl group, an oxymethylene group, an oxyethylene group, an oxypropylene group, or an amide group.

[0071] Examples of the hydrophilic monomer (B-3) include a monofunctional monomer having one polymerizable group in one molecule and a bifunctional monomer having two polymerizable groups in one molecule.

[0072] Among the hydrophilic monomers (B-3), examples of the monofunctional monomer include hydrophilic monofunctional (meth)acrylate monomers such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 1,3-dihydroxypropyl (meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, and 2-((meth)acryloyloxy)ethyltrimethylammonium chloride; and N-methylol (meth)acrylamide. and hydrophilic monofunctional (meth)acrylamide monomers such as N-hydroxyethyl(meth)acrylamide, N,N-bis(2-hydroxyethyl)(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-ethoxymethyl(meth)acrylamide, diacetone(meth)acrylamide, 4-(meth)acryloylmorpholine, N-trihydroxymethyl-N-methyl(meth)acrylamide, N,N-dimethylacrylamide, and N,N-diethylacrylamide.

[0073] Examples of the bifunctional monomer include hydrophilic bifunctional (meth)acrylate monomers such as polyethylene glycol di(meth)acrylate (average number of moles of oxyethylene groups added: 9 or more), 1,2-bis(3-(meth)acryloyloxy-2-hydroxypropoxy)ethane, and 3-(meth)acryloyloxy-2-hydroxypropyl(meth)acrylate.

[0074] Among these hydrophilic monomers (B-3), from the viewpoint of adhesion to tooth structure, 2-hydroxyethyl (meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, and hydrophilic monofunctional (meth)acrylamide monomers are preferred, and 2-hydroxyethyl (meth)acrylate, N,N-dimethylacrylamide, and N,N-diethylacrylamide are more preferred.

[0075] From the viewpoint of adhesion to tooth structure, the content of the hydrophilic monomer (B-3) in the dental adhesive composition is preferably 5 to 60 mass %, more preferably 7 to 50 mass %, even more preferably 10 to 45 mass %, and particularly preferably 13 to 40 mass %, of the total mass of the dental adhesive composition. When the content of the hydrophilic monomer (B-3) in the dental adhesive composition is equal to or greater than the above-mentioned lower limit, a sufficient effect of improving adhesive strength is likely to be obtained, and when it is equal to or less than the above-mentioned upper limit, the desired mechanical strength and water absorption of the cured product are likely to be obtained.

[0076] The content of the monomer (B) having no acidic group in the dental adhesive composition is preferably 20 to 95 mass %, more preferably 25 to 90 mass %, and even more preferably 30 to 85 mass %, of the total mass of the dental adhesive composition, from the viewpoint of achieving both thin film formation of the cured product and long-term mechanical strength.

[0077] Furthermore, from the viewpoint of adhesion to tooth substance and water absorption of the cured product, the mass ratio of the hydrophobic monomer (B-2) to the hydrophilic monomer (B-3) is preferably hydrophobic monomer (B-2):hydrophilic monomer (B-3) = 1:0.1 to 1:3, more preferably 1:0.2 to 1:2, even more preferably 1:0.3 to 1:1, and particularly preferably 1:0.4 to 1:0.9.

[0078] In a preferred embodiment, the content of the hydrophobic monomer (B-2) is preferably greater than that of the polyfunctional monomer (B-1), from the viewpoints that when combined with a predetermined viscosity and other components such as a filler, the dental adhesive composition can achieve appropriate hydrophobicity, the water absorption rate of the cured product can be easily adjusted, and higher mechanical strength of the cured product can be easily obtained over a long period of time. From the above viewpoints, the mass ratio of the polyfunctional monomer (B-1) to the hydrophobic monomer (B-2) is preferably polyfunctional monomer (B-1):hydrophobic monomer (B-2) = 1:1.1 to 1:500, more preferably 1:1.2 to 1:300, and even more preferably 1:1.3 to 1:200.

[0079] In another preferred embodiment, the content of the hydrophilic monomer (B-3) is preferably greater than that of the polyfunctional monomer (B-1), because this makes it easier to obtain higher adhesive strength to tooth structure over a long period of time and higher mechanical strength of the cured product over a long period of time when combined with other components such as a predetermined viscosity and a filler. From this viewpoint, the mass ratio of the polyfunctional monomer (B-1) to the hydrophilic monomer (B-3) is preferably polyfunctional monomer (B-1):hydrophilic monomer (B-3) = 1:1.1 to 1:150, more preferably 1:1.2 to 1:100, and even more preferably 1:1.3 to 1:80.

[0080] In another preferred embodiment, at least one of the monomer (B-1) having three or more polymerizable groups per molecule, the hydrophobic monomer (B-2) having one or two polymerizable groups per molecule, and the hydrophilic monomer (B-3) having one or two polymerizable groups per molecule contains a monomer having a (meth)acrylamide group. In this preferred embodiment, the hydrophobic monomer (B-2) and / or the hydrophilic monomer (B-3) preferably contain a monomer having a (meth)acrylamide group, and it is more preferred that the hydrophobic monomer (B-2) contain a monomer having a (meth)acrylamide group. For example, when the hydrophobic monomer (B-2) contains a monomer having a (meth)acrylamide group, the hydrophobic monomer (B-2) may contain a monomer having an acrylamide group.

[0081] <Polymerization initiator (C)> The polymerization initiator (C) is an essential component for curing the monomer. The polymerization initiator (C) can improve the mechanical strength and durability (adhesive strength to tooth structure, mechanical strength) of the cured product of the dental adhesive composition, and can reduce the water absorption rate. As the polymerization initiator (C), a photopolymerization initiator (C-1) or a chemical polymerization initiator (C-2) can be used, and each may be blended alone or two or more types may be combined.

[0082] Photopolymerization Initiator (C-1) The dental adhesive composition preferably contains a photopolymerization initiator (C-1) from the viewpoints of adhesion to tooth structure, curing ability, and mechanical strength. The photopolymerization initiator (C-1) is preferably a water-insoluble photopolymerization initiator having a solubility in water of less than 10 g / L at 25°C (hereinafter, sometimes simply referred to as a "water-insoluble photopolymerization initiator") or a water-soluble photopolymerization initiator having a solubility in water of 10 g / L or more at 25°C (hereinafter, sometimes simply referred to as a "water-soluble photopolymerization initiator"). From the viewpoints of curing ability and mechanical strength, it is preferable to contain a water-insoluble photopolymerization initiator. Furthermore, in some embodiments, from the viewpoint of adhesion to tooth structure, a water-soluble photopolymerization initiator can be used in addition to the water-insoluble photopolymerization initiator. The photopolymerization initiator (C-1) can be a known photopolymerization initiator, and one type may be blended alone, or two or more types may be blended in combination.

[0083] Examples of the water-insoluble photopolymerization initiator include (bis)acylphosphine oxides, thioxanthones, ketals, α-diketones, coumarins, anthraquinones, benzoin alkyl ether compounds, and α-aminoketone compounds.

[0084] Among the (bis)acylphosphine oxides, examples of the acylphosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylmethoxyphenylphosphine oxide, 2,4,6-trimethylbenzoylethoxyphenylphosphine oxide, 2,3,5,6-tetramethylbenzoyldiphenylphosphine oxide, and benzoyldi(2,6-dimethylphenyl)phosphonate. Examples of bisacylphosphine oxides include bis(2,6-dichlorobenzoyl)phenylphosphine oxide, bis(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis(2,6-dimethoxybenzoyl)phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and bis(2,5,6-trimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide.

[0085] Examples of the thioxanthones include thioxanthone and 2-chlorothioxanthen-9-one.

[0086] Examples of the ketals include benzyl dimethyl ketal and benzyl diethyl ketal.

[0087] Examples of the α-diketones include diacetyl, benzil, dl-camphorquinone, 2,3-pentadione, 2,3-octadione, 9,10-phenanthrenequinone, 4,4′-oxybenzil, acenaphthenequinone, etc. Among these, dl-camphorquinone is particularly preferred from the viewpoint of having a maximum absorption wavelength in the visible light region.

[0088] Examples of the coumarins include 3,3'-carbonylbis(7-diethylaminocoumarin), 3-(4-methoxybenzoyl)coumarin, 3-thienoylcoumarin, 3-benzoyl-5,7-dimethoxycoumarin, 3-benzoyl-7-methoxycoumarin, 3-benzoyl-6-methoxycoumarin, 3-benzoyl-8-methoxycoumarin, 3-benzoylcoumarin, 7-methoxy-3-(p-nitrobenzoyl)coumarin, 3-(p-nitrobenzoyl)coumarin, 3,5-carbonylbis(7-methoxycoumarin), 3-benzoyl-6-bromo Coumarin, 3,3'-carbonylbiscoumarin, 3-benzoyl-7-dimethylaminocoumarin, 3-benzoylbenzo[f]coumarin, 3-carboxycoumarin, 3-carboxy-7-methoxycoumarin, 3-ethoxycarbonyl-6-methoxycoumarin, 3-ethoxycarbonyl-8-methoxycoumarin, 3-acetylbenzo[f]coumarin, 3-benzoyl-6-nitrocoumarin, 3-benzoyl-7-diethylaminocoumarin, 7-dimethylamino-3-(4-methoxybenzoyl)coumarin, 7-diethylamino-3-(4-methoxybenzoyl) ) coumarin, 7-diethylamino-3-(4-diethylamino)coumarin, 7-methoxy-3-(4-methoxybenzoyl)coumarin, 3-(4-nitrobenzoyl)benzo[f]coumarin, 3-(4-ethoxycinnamoyl)-7-methoxycoumarin, 3-(4-dimethylaminocinnamoyl)coumarin, 3-(4-diphenylaminocinnamoyl)coumarin, 3-[(3-dimethylbenzothiazol-2-ylidene)acetyl]coumarin, 3-[(1-methylnaphtho[1,2-d]thiazol-2-ylidene)acetyl]coumarin, 3,3'-carbo Nylbis(6-methoxycoumarin), 3,3'-carbonylbis(7-acetoxycoumarin), 3,3'-carbonylbis(7-dimethylaminocoumarin), 3-(2-benzothiazolyl)-7-(diethylamino)coumarin, 3-(2-benzothiazolyl)-7-(dibutylamino)coumarin, 3-(2-benzimidazolyl)-7-(diethylamino)coumarin, 3-(2-benzothiazolyl)-7-(dioctylamino)coumarin, 3-acetyl-7-(dimethylamino)coumarin, 3,3'-carbonylbis(7-dibutylaminocoumarin), 3,Examples of compounds include those described in JP-A-9-3109 and JP-A-10-245525, such as 3'-carbonyl-7-diethylaminocoumarin-7'-bis(butoxyethyl)aminocoumarin, 10-[3-[4-(dimethylamino)phenyl]-1-oxo-2-propenyl]-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H,11H-[1]benzopyrano[6,7,8-ij]quinolizin-11-one, and 10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H,11H-[1]benzopyrano[6,7,8-ij]quinolizin-11-one.

[0089] Among the above-mentioned coumarins, 3,3'-carbonylbis(7-diethylaminocoumarin) and 3,3'-carbonylbis(7-dibutylaminocoumarin) are particularly preferred.

[0090] Examples of the anthraquinones include anthraquinone, 1-chloroanthraquinone, 2-chloroanthraquinone, 1-bromoanthraquinone, 1,2-benzanthraquinone, 1-methylanthraquinone, 2-ethylanthraquinone, and 1-hydroxyanthraquinone.

[0091] Examples of the benzoin alkyl ether compounds include benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether.

[0092] Examples of the α-aminoketone compounds include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one.

[0093] Among these water-insoluble photopolymerization initiators, it is preferable to use at least one selected from the group consisting of (bis)acylphosphine oxides, α-diketones, and coumarins, which allows for the production of a dental adhesive composition that is excellent in photocurability in the visible and near-ultraviolet regions and exhibits sufficient photocurability using any of a halogen lamp, a light-emitting diode (LED), and a xenon lamp as a light source.

[0094] The water-soluble photopolymerization initiator improves polymerization curing at the hydrophilic tooth surface interface, achieving high adhesive strength. The water-soluble photopolymerization initiator has a solubility in water at 25°C of 10 g / L or more, preferably 15 g / L or more, more preferably 20 g / L or more, and even more preferably 25 g / L or more. A solubility of 10 g / L or more allows the water-soluble photopolymerization initiator to dissolve sufficiently in the water in the tooth at the adhesive interface, making it easier to achieve a polymerization-promoting effect.

[0095] Examples of the water-soluble photopolymerization initiator include water-soluble thioxanthones; water-soluble acylphosphine oxides; 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one having a (poly)ethylene glycol chain introduced into the hydroxyl group, 1-hydroxycyclohexyl phenyl ketone having a (poly)ethylene glycol chain introduced into the hydroxyl group and / or phenyl group, 1-hydroxycyclohexyl phenyl ketone having a -OCH ２ COO － Na ＋ a compound in which a (poly)ethylene glycol chain is introduced into the hydroxyl group and / or phenyl group of 2-hydroxy-2-methyl-1-phenylpropan-1-one; a compound in which —OCH ２ COO － Na ＋ and α-aminoalkylphenones in which the amino group of an α-aminoalkylphenone such as 2-methyl-1[4-(methylthio)phenyl]-2-morpholinopropan-1-one or 2-benzyl-2-(dimethylamino)-1-[(4-morpholino)phenyl]-1-butanone has been converted into a quaternary ammonium salt.

[0096] Examples of the water-soluble thioxanthones include 2-hydroxy-3-(9-oxo-9H-thioxanthen-4-yloxy)-N,N,N-trimethyl-1-propanaminium chloride, 2-hydroxy-3-(1-methyl-9-oxo-9H-thioxanthen-4-yloxy)-N,N,N-trimethyl-1-propanaminium chloride, 2-hydroxy-3-(9-oxo-9H-thioxanthen-2-yloxy)-N,N,N-trimethyl-1-propanaminium chloride, 2- Hydroxy-3-(3,4-dimethyl-9-oxo-9H-thioxanthen-2-yloxy)-N,N,N-trimethyl-1-propanaminium chloride, 2-hydroxy-3-(3,4-dimethyl-9H-thioxanthen-2-yloxy)-N,N,N-trimethyl-1-propanaminium chloride, 2-hydroxy-3-(1,3,4-trimethyl-9-oxo-9H-thioxanthen-2-yloxy)-N,N,N-trimethyl-1-propanaminium chloride, and the like can be used.

[0097] Among these water-soluble acylphosphine oxides, sodium phenyl(2,4,6-trimethylbenzoyl)phosphinate, lithium phenyl(2,4,6-trimethylbenzoyl)phosphinate, sodium bis(2,4,6-trimethylbenzoyl)phosphinate, and lithium bis(2,4,6-trimethylbenzoyl)phosphinate are preferred.

[0098] The content of the photopolymerization initiator (C-1) is not particularly limited, but from the viewpoint of the curability of the resulting dental adhesive composition, it is preferably 0.01 to 10 mass %, more preferably 0.05 to 7 mass %, and even more preferably 0.1 to 5 mass %, of the total mass of the dental adhesive composition.

[0099] Chemical Polymerization Initiator (C-2) The dental adhesive composition may further contain a chemical polymerization initiator (C-2) from the viewpoint of enabling chemical polymerization and improving cavity sealing properties in areas where light does not reach. One type of chemical polymerization initiator (C-2) may be used alone, or two or more types may be used in combination. As the chemical polymerization initiator (C-2), an organic peroxide is preferred.

[0100] The organic peroxide used in the chemical polymerization initiator (C-2) is not particularly limited, and known organic peroxides can be used. Typical organic peroxides include ketone peroxides, hydroperoxides, diacyl peroxides, dialkyl peroxides, peroxyketals, peroxyesters, and peroxydicarbonates. Specific examples of these organic peroxides include those described in WO 2008 / 087977.

[0101] The content of the chemical polymerization initiator (C-2) is not particularly limited, but from the viewpoint of the curability of the resulting dental adhesive composition, it is preferably 0.01 to 10 mass %, more preferably 0.05 to 7 mass %, and even more preferably 0.1 to 5 mass %, of the total mass of the dental adhesive composition.

[0102] <Water (D)> The water (D) in the present invention promotes the decalcification action of the monomer (A) having an acidic group. The water (D) used must be substantially free of impurities that adversely affect adhesiveness, and distilled water or ion-exchanged water is preferred. If the content of water (D) is either too high or too low, the adhesive strength to tooth structure may decrease. The content of water (D) is preferably 1 to 50% by mass, more preferably 5 to 30% by mass, and even more preferably 10 to 20% by mass, of the total mass of the dental adhesive composition.

[0103] <Volatile Organic Solvent (E)> The dental adhesive composition of the present invention needs to contain a volatile organic solvent (E) from the viewpoints of improving adhesive strength to tooth structure, coatability, thinning of the cured product, and preventing phase separation of each component. The volatile organic solvent (E) contributes to adjusting the viscosity of the dental adhesive composition, and can form a thin film of the cured product together with other components. Furthermore, the organic solvent to be contained in the dental adhesive composition of the present invention needs to be volatile from the viewpoint of application to applications such as resin coating methods. One type of volatile organic solvent (E) may be used alone, or two or more types may be used in combination.

[0104] The volatile organic solvent (E) is preferably a water-soluble volatile organic solvent from the viewpoint of compatibility with each component of the dental adhesive composition. The volatile organic solvent preferably has a boiling point of 150° C. or less under normal pressure, and more preferably has a boiling point of 100° C. or less under normal pressure.

[0105] Furthermore, the water-soluble volatile organic solvent is preferably one having a solubility in water at 25°C of 5% by mass or more, more preferably one having a solubility in water at 25°C of 30% by mass or more, and even more preferably one that can be dissolved in water in any proportion.

[0106] Specific examples of the volatile organic solvent (E) include alcohol solvents such as ethanol, methanol, 1-propanol, and isopropyl alcohol; ketone solvents such as acetone and methyl ethyl ketone; and ether solvents such as 1,2-dimethoxyethane, 1,2-diethoxyethane, and tetrahydrofuran. Among these, alcohol solvents are preferred from the viewpoints of excellent compatibility, prevention of phase separation of the components, and superior storage stability.

[0107] If the content of the volatile organic solvent (E) is excessive, the adhesive strength may decrease. The content of the volatile organic solvent (E) is preferably 1 to 70 mass %, more preferably 5 to 50 mass %, and even more preferably 10 to 30 mass %, of the total mass of the dental adhesive composition, in order to obtain a desired viscosity as the dental adhesive composition.

[0108] <Filler (F)> The dental adhesive composition contains a filler (F) in order to adjust the curability, the water absorption rate of the cured product, the mechanical strength when the cured product is formed into a thin film, and the handleability. Examples of the filler (F) include inorganic fillers, organic-inorganic composite fillers, and organic fillers. One type of filler (F) may be used alone, or two or more types may be used in combination.

[0109] Examples of inorganic fillers include various glasses such as fused silica, quartz, soda lime silica glass, E glass, C glass, borosilicate glass (Pyrex (registered trademark) glass), strontium borosilicate glass, fluoroaluminosilicate glass, aluminosilicate glass, calcium fluoroaluminosilicate glass, strontium fluoroaluminosilicate glass, strontium calcium fluoroaluminosilicate glass, and barium glass (barium silicate glass, barium boroaluminosilicate glass, and barium fluoroaluminosilicate glass); and lanthanum glass ceramics. Examples of suitable silica-containing composite oxides include fused silica, various ceramics, alumina, composite oxides (e.g., silica-titania, silica-titania-barium oxide, silica-zirconia, silica-alumina, and silica-alumina-zirconia), ytterbium oxide, silica-coated ytterbium fluoride, diatomaceous earth, kaolin, clay minerals (e.g., montmorillonite), activated clay, synthetic zeolite, mica, calcium fluoride, ytterbium fluoride, yttrium fluoride, calcium phosphate, barium sulfate, zirconium oxide, titanium oxide, and hydroxyapatite. These may be used alone or in combination of two or more. Of the above, from the viewpoint of storage stability, fused silica and silica-zirconia are preferred, and fused silica is more preferred.

[0110] In one embodiment, the inorganic filler material preferably contains various glasses (containing silica as a main component (containing 5% by mass or more of silica, preferably 10% by mass or more of silica), and, as necessary, oxides of heavy metals, boron, aluminum, or the like).

[0111] From the viewpoint of the handleability and mechanical strength of the obtained dental adhesive composition, the average particle size of the inorganic filler is preferably 0.001 to 50 μm, more preferably 0.001 to 1 μm, even more preferably 0.005 to 0.1 μm, and particularly preferably 0.005 to 0.05 μm. In the present invention, when the inorganic filler is surface-treated as described below, the average particle size of the inorganic filler means the average particle size before the surface treatment. One preferred embodiment is a dental adhesive composition in which the filler (F) is an inorganic filler.

[0112] Commercially available inorganic fillers may be used. Commercially available products include, for example, silica such as Aerosil (registered trademark) 90, Aerosil (registered trademark) 130, Aerosil (registered trademark) 150, Aerosil (registered trademark) 200, Aerosil (registered trademark) 255, Aerosil (registered trademark) 300, Aerosil (registered trademark) 380, Aerosil (registered trademark) OX50, Aerosil (registered trademark) R972 (all manufactured by Nippon Aerosil Co., Ltd.), GM27884, 8235 (all manufactured by SCHOTT), barium glass such as product code "E-3000" (manufactured by Estech), strontium borosilicate glass (E-4000, manufactured by ESSTECH), lanthanum glass ceramics (GM31684, manufactured by Schott), fluoroaluminosilicate glass (GM35429, G018-091, G018-117, manufactured by Schott), and the like. As the filler (F), silica having a small primary particle size such as Aerosil (registered trademark) 90, Aerosil (registered trademark) 130, Aerosil (registered trademark) 150, Aerosil (registered trademark) 200, Aerosil (registered trademark) 255, Aerosil (registered trademark) 300, Aerosil (registered trademark) 380, Aerosil (registered trademark) OX50, and Aerosil (registered trademark) R972 is preferred in terms of adhesive strength, coatability, and the like.

[0113] The inorganic filler may be amorphous, crystalline, or a mixture of both, but preferably contains at least an amorphous portion. The shape of the inorganic filler is not particularly limited and can be appropriately selected and used.

[0114] The inorganic filler is preferably surface-treated in advance with a known surface treatment agent such as a silane coupling agent in order to adjust the mechanical strength and fluidity of the dental adhesive composition and to set the viscosity of the dental adhesive composition within a desired range. For example, by surface-treating the hydroxyl groups present on the surface of the inorganic filler with a surface treatment agent, an inorganic filler with the hydroxyl groups surface-treated can be obtained. The thickening effect due to the addition of the filler can be suppressed.

[0115] Examples of the surface treatment agent include silane coupling agents such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltrichlorosilane, vinyltri(β-methoxyethoxy)silane, 3-methacryloyloxypropyltrimethoxysilane, 8-methacryloyloxyoctyltrimethoxysilane, 11-methacryloyloxyundecyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-aminopropyltriethoxysilane, of which vinyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 8-methacryloyloxyoctyltrimethoxysilane, 11-methacryloyloxyundecyltrimethoxysilane, and γ-aminopropyltriethoxysilane are preferred.

[0116] The surface treatment method can be any known method without particular limitation. Examples of surface treatment methods include spraying the surface treatment agent onto the inorganic filler while vigorously stirring it; dispersing or dissolving the inorganic filler and the surface treatment agent in a suitable solvent and then removing the solvent; or hydrolyzing the alkoxy groups of the surface treatment agent in an aqueous solution with an acid catalyst to convert them to silanol groups, attaching them to the inorganic filler surface in the aqueous solution, and then removing the water. In any of these methods, the reaction between the inorganic filler surface and the surface treatment agent is typically completed by heating in the range of 50 to 150°C, thereby achieving surface treatment. The amount of surface treatment is not particularly limited; for example, 0.1 to 40 parts by mass of the surface treatment agent can be used per 100 parts by mass of the inorganic filler before treatment.

[0117] The organic-inorganic composite filler is obtained by adding a monomer to the inorganic filler described above, forming a paste, polymerizing it, and pulverizing it. The organic-inorganic composite filler refers to a filler containing an inorganic filler and a polymer of a monomer. Examples of the monomer include a monomer (A) having an acidic group and a monomer (B) not having an acidic group, with a hydrophobic monomer (B-2) being preferred. Examples of the organic-inorganic composite filler include a mixture of Bis-GMA, 3G, and a surface-treated silica filler, polymerized, and then pulverized. The shape of the organic-inorganic composite filler is not particularly limited, and the particle size of the filler can be appropriately selected. The organic-inorganic composite filler may also be used alone or in combination with two or more types. It is preferable that the organic-inorganic composite filler is also surface-treated from the perspective of mechanical strength. Examples and preferred types of surface treatment agents are the same as those for the inorganic filler. From the viewpoint of the handleability and mechanical strength of the resulting dental adhesive composition, the average particle size of the organic-inorganic composite filler is preferably 0.001 to 50 μm, more preferably 0.001 to 20 μm, and even more preferably 0.005 to 15 μm.

[0118] Examples of organic filler materials include polymethyl methacrylate, polyethyl methacrylate, methyl methacrylate-ethyl methacrylate copolymer, cross-linked polymethyl methacrylate, cross-linked polyethyl methacrylate, polyamide, polyvinyl chloride, polystyrene, chloroprene rubber, nitrile rubber, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer, acrylonitrile-styrene copolymer, and acrylonitrile-styrene-butadiene copolymer. These may be used alone or in combination of two or more. The shape of the organic filler is not particularly limited, and the particle size of the filler can be appropriately selected. From the viewpoints of the handleability and mechanical strength of the resulting dental adhesive composition, the average particle size of the organic filler is preferably 0.001 to 50 μm, more preferably 0.001 to 20 μm, and even more preferably 0.005 to 15 μm.

[0119] In this specification, the average particle size of the filler can be determined by laser diffraction scattering or electron microscope observation of the particles. Specifically, laser diffraction scattering is convenient for measuring particle sizes of 0.1 μm or more, while electron microscope observation is convenient for measuring the particle size of ultrafine particles less than 0.1 μm. 0.1 μm is the value measured by laser diffraction scattering. In the case of particles formed by agglomerated primary particles, there are an average particle size of the primary particles and an average particle size of the secondary particles, and the average particle size of the filler is the average particle size of the secondary particles with a larger particle size.

[0120] Specifically, the laser diffraction scattering method can be performed by using a laser diffraction particle size distribution analyzer (SALD-2300, manufactured by Shimadzu Corporation) on a volume basis using a 0.2% aqueous solution of sodium hexametaphosphate as a dispersion medium.

[0121] Specifically, electron microscope observation can be performed by taking a photograph of the particles using an electron microscope (S-4000 model, manufactured by Hitachi, Ltd.) and measuring the particle diameters of particles (200 or more) observed within a unit field of view of the photograph using image analysis particle size distribution measurement software (Mac-View (manufactured by Mountec Co., Ltd.)). In this case, the particle diameter is determined as the arithmetic mean value of the longest and shortest lengths of the particles, and the average particle diameter is calculated from the number of particles and their particle diameters.

[0122] The refractive index of the filler (F) is not particularly limited and may be, for example, 1.35 or more and 2.00 or less. From the viewpoint of the transparency of the cured product, the refractive index of the filler (F) is preferably 1.40 or more and 1.70 or less. The refractive index of the filler (F) can be controlled by adjusting the type and / or content ratio of the components of the filler (F). In this specification, the refractive index of the object to be measured (filler (F), colorant, etc.) can be measured using an Abbe refractometer.

[0123] The content of the filler (F) is not particularly limited, but from the viewpoints of obtaining a desired viscosity for the dental adhesive composition, enabling the cured product to be thin, and the water absorption rate, handleability, and mechanical strength of the cured product, it is preferably 0.1 to 30 mass %, more preferably 0.5 to 20 mass %, and even more preferably 1 to 10 mass %, of the total mass of the dental adhesive composition. By combining a filler (F) content within this range with other components, the dental adhesive composition will have a desired viscosity range, and even though the bond layer, which is the cured product, is very thin, a decrease in mechanical strength can be suppressed, and high mechanical strength can be easily obtained over a long period of time.

[0124] <Polymerization Accelerator (G)> From the viewpoint of the mechanical strength of the cured product, the dental adhesive composition preferably contains a polymerization accelerator (G).

[0125] Examples of the polymerization accelerator (G) used in the present invention include amines, sulfinic acid and its salts, borate compounds, barbituric acid compounds, triazine compounds, copper compounds, tin compounds, vanadium compounds, halogen compounds, aldehydes, thiol compounds, sulfites, hydrogen sulfites, thiourea compounds, etc. The polymerization accelerator (G) may be used alone or in combination of two or more.

[0126] Amines used as the polymerization accelerator (G) are divided into aliphatic amines and aromatic amines. Examples of aliphatic amines include primary aliphatic amines such as n-butylamine, n-hexylamine, and n-octylamine; secondary aliphatic amines such as diisopropylamine, dibutylamine, and N-methylethanolamine; and tertiary aliphatic amines such as N-methyldiethanolamine, N-ethyldiethanolamine, N-n-butyldiethanolamine, N-lauryldiethanolamine, 2-(dimethylamino)ethyl methacrylate, N-methyldiethanolamine dimethacrylate, N-ethyldiethanolamine dimethacrylate, triethanolamine monomethacrylate, triethanolamine dimethacrylate, triethanolamine trimethacrylate, triethanolamine, trimethylamine, triethylamine, and tributylamine. Among these, tertiary aliphatic amines are preferred from the viewpoint of the curability and storage stability of the dental adhesive composition, and N-methyldiethanolamine and triethanolamine are more preferably used.

[0127] Examples of aromatic amines include N,N-bis(2-hydroxyethyl)-3,5-dimethylaniline, N,N-bis(2-hydroxyethyl)-p-toluidine, N,N-bis(2-hydroxyethyl)-3,4-dimethylaniline, N,N-bis(2-hydroxyethyl)-4-ethylaniline, N,N-bis(2-hydroxyethyl)-4-isopropylaniline, N,N-bis(2-hydroxyethyl)-4-t-butylaniline, N,N-bis(2-hydroxyethyl)-3,5-diisopropylaniline, N,N-bis(2-hydroxyethyl)-3,5-di-t-butylaniline, N,N-dimethylaniline, N,N-dimethyl-p-toluidine, N,N-dimethyl-m-toluidine, and N,N-diethyl-p -toluidine, N,N-dimethyl-3,5-dimethylaniline, N,N-dimethyl-3,4-dimethylaniline, N,N-dimethyl-4-ethylaniline, N,N-dimethyl-4-isopropylaniline, N,N-dimethyl-4-t-butylaniline, N,N-dimethyl-3,5-di-t-butylaniline, 4-(N,N-dimethylamino)ethyl benzoate, 4-(N,N-dimethylamino)methyl benzoate, 4-(N,N-dimethylamino)propyl benzoate, 4-(N,N-dimethylamino)n-butoxyethyl benzoate, 4-(N,N-dimethylamino)2-(methacryloyloxy)ethyl benzoate, 4-(N,N-dimethylamino)benzophenone, and 4-(N,N-dimethylamino)butyl benzoate. Among these, at least one selected from the group consisting of N,N-bis(2-hydroxyethyl)-p-toluidine, ethyl 4-(N,N-dimethylamino)benzoate, n-butoxyethyl 4-(N,N-dimethylamino)benzoate, and 4-(N,N-dimethylamino)benzophenone is preferably used from the viewpoint of being able to impart excellent curability to the dental adhesive composition.

[0128] Specific examples of sulfinic acids and salts thereof, borate compounds, barbituric acid compounds, triazine compounds, copper compounds, tin compounds, vanadium compounds, halogen compounds, aldehydes, thiol compounds, sulfites, hydrogen sulfites, and thiourea compounds include those described in WO 2008 / 087977.

[0129] The content of the polymerization accelerator (G) used in the present invention is not particularly limited, but from the viewpoint of the curability and mechanical strength of the resulting dental adhesive composition, it is preferably in the range of 0.01 to 10 mass %, more preferably 0.05 to 7 mass %, and even more preferably 0.1 to 5 mass %, of the total mass of the dental adhesive composition.

[0130] The dental adhesive composition may further contain a fluoride ion-releasing substance. By including a fluoride ion-releasing substance, a dental adhesive composition capable of imparting acid resistance to tooth structure can be obtained. Examples of such fluoride ion-releasing substances include fluoride ion-releasing polymers such as copolymers of methyl methacrylate and methacrylic acid fluoride; and metal fluorides such as sodium fluoride, potassium fluoride, sodium monofluorophosphate, lithium fluoride, and ytterbium fluoride. The above fluoride ion-releasing substances may be contained alone or in combination of two or more. The content of the fluoride ion-releasing substance is preferably 0.0001 to 10% by mass, more preferably 0.005 to 5% by mass, and even more preferably 0.01 to 2% by mass, based on the total mass of the dental adhesive composition.

[0131] The dental adhesive composition may contain known additives within the range that does not impair performance. Examples of such additives include polymerization inhibitors, antioxidants, colorants (pigments, dyes), ultraviolet absorbers, fluorescent agents, silane coupling agents, thickeners, etc. One type of additive may be used alone, or two or more types may be used in combination.

[0132] The dental adhesive composition of the present invention preferably contains a polymerization inhibitor from the viewpoints of storage stability and adjustment of curing properties. Examples of polymerization inhibitors include hydroquinone, hydroquinone monomethyl ether, dibutylhydroquinone, dibutylhydroquinone monomethyl ether, t-butylcatechol, 2-t-butyl-4,6-dimethylphenol, 2,6-di-t-butylphenol, and 3,5-di-t-butyl-4-hydroxytoluene. These may be used alone or in combination of two or more. The content of the polymerization inhibitor is preferably 0.001 to 1.0% by mass of the total mass of the dental adhesive composition.

[0133] The dental adhesive composition of the present invention preferably contains an ultraviolet absorber from the viewpoint of photostability against ambient light such as fluorescent lamps and LEDs, and from the viewpoint of suppressing discoloration of the cured product. Examples of ultraviolet absorbers include benzotriazole compounds such as 2-(2-hydroxyphenyl)benzotriazole, 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-5-ethylphenyl)benzotriazole, 2-(2-hydroxy-5-propylphenyl)benzotriazole, 2-(2-hydroxy-5-tert-octylphenyl)benzotriazole, and 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole (Tinuvin 326), as well as benzimidazole compounds, with Tinuvin 326 being preferred. These may be used alone or in combination of two or more.

[0134] From the viewpoints of adhesion to tooth structure and long-term mechanical strength, the dental adhesive composition of the present invention preferably contains a silane coupling agent in addition to the surface treatment agent for the filler. Examples of the silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltrichlorosilane, vinyltri(β-methoxyethoxy)silane, 3-methacryloyloxypropyltrimethoxysilane, 8-methacryloyloxyoctyltrimethoxysilane, 11-methacryloyloxyundecyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane, and the like. Examples of suitable silane coupling agents include silane and 3-(meth)acryloyloxypropyldimethylmonomethoxysilane. From the viewpoint of adhesiveness, vinyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 8-methacryloyloxyoctyltrimethoxysilane, 11-methacryloyloxyundecyltrimethoxysilane, γ-aminopropyltriethoxysilane, 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane, 3-(meth)acryloyloxypropyldimethylmonomethoxysilane, and hydrolysates thereof are preferred. The silane coupling agents may be used alone or in combination of two or more. The content of the silane coupling agent is preferably 0.001 to 30% by mass, more preferably 0.05 to 20% by mass, and even more preferably 0.1 to 10% by mass, based on the total mass of the dental adhesive composition.

[0135] An example of a suitable composition ratio for a dental adhesive composition is shown below: The dental adhesive composition contains, based on the total mass of the dental adhesive composition, 1 to 50 mass% of a monomer (A) having an acidic group, 0.1 to 20 mass% of a monomer (B-1) having three or more polymerizable groups in one molecule, 5 to 60 mass% of a hydrophobic monomer (B-2), 5 to 60 mass% of a hydrophilic monomer (B-3), 0.01 to 10 mass% of a photopolymerization initiator (C-1), 1 to 50 mass% of water (D), 1 to 70 mass% of a volatile organic solvent (E), 0.1 to 30 mass% of a filler (F), and 0.01 to 10 mass% of a polymerization accelerator (G). It is preferable that the composition contains 1 to 30% by mass of a monomer (A) having an acidic group, 0.5 to 15% by mass of a monomer (B-1) having three or more polymerizable groups in one molecule, 10 to 50% by mass of a hydrophobic monomer (B-2), 7 to 50% by mass of a hydrophilic monomer (B-3), 0.05 to 7% by mass of a photopolymerization initiator (C-1), 5 to 30% by mass of water (D), 5 to 50% by mass of a volatile organic solvent (E), 0.5 to 20% by mass of a filler (F), and 0.05 to 7% by mass of a polymerization accelerator (G).

[0136] The dental adhesive composition can be easily produced by a method known to those skilled in the art, using a monomer (A) having an acidic group, a monomer (B) not having an acidic group, a polymerization initiator (C), water (D), a volatile organic solvent (E), and a filler (F), and further containing other components as necessary.

[0137] The dental adhesive composition of the present invention can be suitably used as a dental bonding material or a dental coating material, and is particularly suitable as a dental bonding material or a dental coating material for resin coating applications. The dental adhesive composition of the present invention has a viscosity of less than 40 cps at 30°C as measured by a Brookfield viscometer, and can form a thin coating layer within a temperature range expected for use at room temperature in a dental clinic (e.g., 35°C or lower). The dental adhesive composition of the present invention may be combined with a dental etching material, a dental primer, or the like. The dental etching material and the dental primer may be used alone or in combination. The dental etching material, dental primer, and the like are not particularly limited, and commercially available products can be used.

[0138] <Specific Application Method and Procedure> The dental adhesive composition is applied to the surface of the tooth to be applied. The dental adhesive composition is applied, and the water (D) and volatile organic solvent (E) in the dental adhesive composition are removed using an air blower with an appropriately adjusted pressure so that the dental adhesive composition does not move away from the application site and disappear. Thereafter, in the case of a dental adhesive composition containing a photopolymerization initiator (C-1), the dental adhesive composition is irradiated with light using a dental light irradiator to harden it. In the case of a dental adhesive composition containing a chemical polymerization initiator (C-2), the composition may be left to stand until hardening is complete. Thereafter, if necessary, a dental composite resin prepared separately is filled in. The dental composite resin is not particularly limited, and a commercially available product can be used.

[0139] When a dental adhesive composition is combined with a dental etching material, a dental primer, or the like, the dental etching material, the dental primer, or the like is used before applying the dental adhesive composition.

[0140] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the examples, parts are by mass unless otherwise specified.

[0141] Next, the components of the dental adhesive compositions of the Examples and Comparative Examples are listed below together with their abbreviations.

[0142] [Monomer (A) having an acidic group] MDP: 10-methacryloyloxydecyl dihydrogen phosphate GDPMP: 1,3-glycerol dimethacrylate phosphate 4-META: 4-methacryloyloxyethyl trimellitic anhydride

[0143] [Monomer (B) not having an acidic group] Monomer (B-1) having three or more polymerizable groups in one molecule TMPMA: trimethylolpropane tri(meth)acrylate (solubility in water at 25°C: less than 10% by mass) U4TH: N,N-(2,2,4-trimethylhexamethylene)bis[2-(aminocarboxy)propane-1,3-diol]tetramethacrylate (solubility in water at 25°C: less than 10% by mass) TAC4: N,N',N'',N'''-tetraacryloyltriethylenetetramine (solubility in water at 25°C: 10% by mass or more) DTMP: ditrimethylolpropane tetramethacrylate (solubility in water at 25°C: less than 10% by mass) Bis-4: compound of formula (3) (solubility in water at 25°C: less than 10% by mass) Hydrophobic Monomer (B-2) Bis-GMA: 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl]propane 3G: triethylene glycol dimethacrylate MAEA: N-methacryloyloxyethyl acrylamide UDMA: [2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)]dimethacrylate NPG: neopentyl glycol dimethacrylate Hydrophilic Monomer (B-3) DEAA: N,N-diethylacrylamide HEMA: 2-hydroxyethyl methacrylate #801: 1,2-bis(3-methacryloyloxy-2-hydroxypropoxy)ethane

[0144] [Photopolymerization initiator (C-1)] CQ: dl-camphorquinone BAPO: bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide TMDPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide

[0145] [Water (D)] Purified water

[0146] [Volatile organic solvent (E)] Ethanol Acetone

[0147] [Filler (F)] R972: Hydrophobic fumed silica, ultrafine silica particle "Aerosil (registered trademark) R972" manufactured by Nippon Aerosil Co., Ltd., average particle size: 16 nm (silica), refractive index: 1.46

[0148] [Polymerization accelerator (G)] DABE: ethyl 4-(N,N-dimethylamino)benzoate DEPT: N,N-bis(2-hydroxyethyl)-p-toluidine

[0149] [Others] BHT: 3,5-di-t-butyl-4-hydroxytoluene (polymerization inhibitor) KBM-503: 3-methacryloyloxypropyltrimethoxysilane (silane coupling agent) Sodium fluoride

[0150] Examples 1 to 21 and Comparative Examples 1 to 7 Preparation of Dental Adhesive Compositions Among the raw materials shown in Tables 1 to 3, the components other than the filler, water, and volatile organic solvent were first mixed, then the filler was added and mixed, and water and the volatile organic solvent were further added to obtain a mixture. The mixture was stirred at room temperature (23°C) in a dark place until homogenized, and then ultrasonically degassed to prepare a liquid dental adhesive composition.

[0151] Test Example 1 Water Absorption The prepared liquid dental adhesive composition was placed in a screw bottle, and air was continuously blown onto it to volatilize the water and volatile organic solvent in the dental adhesive composition.The composition was then filled into a SUS mold (diameter 15 mm, thickness 1.0 mm), and the top and bottom (15 mm diameter surface) were sandwiched between polyester films, and then pressed with a slide glass.Then, in the pressed state, using a dental visible light irradiator (Pencure 2000, manufactured by Morita Corporation), light was irradiated from above and below the composition in standard mode at five locations on each side for 10 seconds each (a total of 50 seconds of light irradiation on each side), and the composition was cured to obtain a cured product.Ten samples of the cured product were prepared for each example and comparative example, and the cured product was removed from the mold, and the mass of the sample was measured and measured. １ Then, five of the sheets were left in a container immersed in distilled water (30 mL) in an incubator set at 37°C for 24 hours, and the remaining five sheets were left in an incubator set at 37°C for 7 days. Then, they were taken out of the distilled water, and the adhering water was removed, and the weighed mass was measured. ２ It was decided.

[0152] The water absorption was calculated using the following formula. Measurements were taken for each cured sample, and the average value was calculated (n=5). ｓｐ (%) = (m ２ -m １ ) / m １ (g / g)×100 m １ : Mass (μg) of sample after immersion in water for 24 hours ２ : mass of sample before immersion in water (μg)

[0153] The water absorption rate of the cured product of the dental adhesive composition of the present invention when immersed at 37°C for 24 hours (hereinafter also referred to as "initial water absorption rate") is 4.0% or less, preferably 3.5% or less, more preferably 3.0% or less, even more preferably 2.5% or less, and particularly preferably less than 2.3%, from the viewpoints of the mechanical strength, adhesion to tooth structure, and durability of the cured product. If the water absorption rate exceeds 4.0%, the mechanical strength and adhesion to tooth structure of the cured product may be insufficient.

[0154] The water absorption rate of the cured product of the dental adhesive composition of the present invention when immersed at 37°C for 7 days (hereinafter also referred to as "durable water absorption rate") is preferably 7.5% or less, more preferably 7.0% or less, even more preferably 6.5% or less, and particularly preferably less than 6.0%, from the viewpoints of the mechanical strength of the cured product over a long period of time, adhesion to tooth structure, and durability.

[0155] Test Example 2: Shear Bond Strength (Enamel, Dentin) The dental adhesive composition of the present invention exhibits excellent bond strength to tooth tissue over a long period of time, and can protect exposed dentin for a long period of time in resin coating applications, making it suitable for use in indirect restorations. Furthermore, the dental adhesive composition of the present invention exhibits excellent bond strength to tooth tissue and good cavity sealing properties, making it suitable for use as a dental adhesive composition for general direct restorations. While this test example was designed for direct restorations, there is essentially no difference in terms of adhesion to tooth tissue when used in resin coating applications. This test example can also be used to evaluate bond strength to tooth tissue for resin coating applications. The test was conducted in accordance with ISO 29022:2013. Specifically, the procedure is as follows. The labial surfaces of bovine teeth were polished under running water with #80 silicon carbide paper (manufactured by Nihon Kenshi Co., Ltd.) to obtain samples exposing the flat surface of the enamel and samples exposing the flat surface of the dentin. First, the shear bond strength to enamel was measured using samples with the flat enamel surface exposed, using the following method. A separately prepared 15-hole mold (15-hole mold, Ultradent, φ35 mm x H25 mm) was attached to the bottom surface of which the sample bovine tooth was fixed. Next, dental impression tray resin (trade name "Tray Resin II", Matsufu Co., Ltd.) was filled into the mold and allowed to stand for approximately 30 minutes to harden the dental impression tray resin, yielding a composite of the bovine tooth and cured resin. This composite was then removed from the mold as a sample. The bovine tooth was exposed on the upper surface of the cured resin. The upper surface of the sample was polished under running water with #600 silicon carbide paper (Nihon Kenshi Co., Ltd.) to a size sufficient for adhesion (φ2.38 mm or larger), and the adhesion surface was then ultrasonically washed for 5 minutes.

[0156] Next, the dental adhesive composition (adhesive) prepared in each Example and Comparative Example was applied to the surface of a bovine tooth and allowed to stand for 3 seconds. After this, the water and volatile organic solvent were evaporated with a mild air blow. The adhesive was then photocured by irradiating it with light in standard mode for 10 seconds using a dental visible light irradiator (PenCure 2000, manufactured by Morita Corporation). A separately prepared φ2.38 mm CR filling mold (Bonding Mold Insert, manufactured by Ultradent) was attached to a dedicated tool (Bonding Clamp, manufactured by Ultradent). Next, the CR filling mold attached to the dedicated tool was lowered to secure the sample in place so that it was in close contact with the surface to be bonded. Next, Clearfil® AP-X (manufactured by Kuraray Noritake Dental Co., Ltd.) was thinly filled into the hole in the CR filling mold to a thickness of 1 mm or less. The CR filling mold was then filled again with Clearfil (registered trademark) AP-X (up to about 2 / 3 of the mold, approximately 2 mm thick), and the Clearfil (registered trademark) AP-X was cured by irradiating it with light for 20 seconds in standard mode using a dental visible light irradiator (Pencure 2000, manufactured by Morita Corporation). The samples were removed from the CR filling mold and used as adhesion test samples. 20 adhesion test samples were prepared. Next, the adhesion test samples were immersed in distilled water in a container and left in an incubator set at 37°C for 24 hours, and the shear bond strength of 10 samples was measured immediately after removal from the distilled water (hereinafter also referred to as "initial shear bond strength"). The average value of the measurement results is shown in each table as "initial." For the remaining 10 samples, to evaluate the adhesive durability, they were subjected to 4,000 thermal cycles, each cycle consisting of alternating immersion in cold water at 4°C and hot water at 60°C for 1 minute, and then the shear adhesive strength was measured (hereinafter also referred to as "durable shear adhesive strength"). The average value of the measurement results is shown in each table as "durability."The adhesive strength (shear bond strength) was measured by attaching the adhesive test sample to a dedicated holder (Test Base Clamp, Ultradent), and measuring it using a dedicated jig (Crosshead Assembly, Ultradent) and a universal testing machine (Shimadzu Corporation) at a crosshead speed of 1 mm / min, and the average values ​​are shown in the tables (n = 10). Similarly to the shear bond strength to enamel, the shear bond strength to dentin was also measured, and the average values ​​are shown in each table (n = 10).

[0157] The initial shear bond strength of the dental adhesive composition of the present invention to enamel is preferably 15 MPa or more, more preferably 20 MPa or more, and even more preferably 25 MPa or more. The durable shear bond strength to enamel is preferably 10 MPa or more, more preferably 15 MPa or more, and even more preferably 20 MPa or more.

[0158] The initial shear bond strength of the dental adhesive composition of the present invention to dentin is preferably 15 MPa or more, more preferably 20 MPa or more, and even more preferably 25 MPa or more. The durable shear bond strength to dentin is preferably 10 MPa or more, more preferably 15 MPa or more, and even more preferably 20 MPa or more.

[0159] Test Example 3: Tensile Strength Test An appropriate amount of each dental adhesive composition prepared was added to a glass beaker, and the water and volatile organic solvent contained in the dental adhesive composition were evaporated by continuously blowing air into the beaker while stirring. A polyester film was placed on a glass slide, and a 1 mm x 1 mm x 10 mm Teflon® mold was placed on top of it. Next, the dental adhesive composition from which the water and volatile organic solvent had evaporated was poured into the Teflon® mold, sandwiched between the polyester and the glass slide, and then photocured by irradiating the front and back surfaces with light using a dental visible light irradiator (Pencure 2000, manufactured by Morita Corporation) in normal mode for 10 seconds. The resulting cured product was removed from the Teflon® mold, and excess burrs were removed. Ten samples were prepared for each test. The prepared samples were immersed in distilled water in a container and left in an incubator set at 37 ° C for 24 hours. The tensile strength was measured at a crosshead speed of 1.0 mm / min using a universal testing machine (Autograph AG-I 100 kN, manufactured by Shimadzu Corporation) (n = 5), and the average value was calculated. The average value of the measurement results is shown in each table as "initial." The remaining five samples were immersed in distilled water in a container and left in an incubator set at 37 ° C for 7 days. The tensile strength was measured at a crosshead speed of 1.0 mm / min using a universal testing machine (Autograph AG-I 100 kN, manufactured by Shimadzu Corporation) (n = 5), and the average value was calculated. The average value of the measurement results is shown in each table as "durability."

[0160] The tensile strength of the dental adhesive composition of the present invention when immersed at 37°C for 1 day (hereinafter also referred to as "initial tensile strength") is preferably 40 MPa or more, more preferably 45 MPa or more, and even more preferably 50 MPa or more, from the viewpoints of the mechanical strength of the cured product, adhesion to tooth structure, and durability.

[0161] The tensile strength of the dental adhesive composition of the present invention when immersed at 37°C for 7 days (hereinafter also referred to as "durable tensile strength") is preferably 25 MPa or more, more preferably 35 MPa or more, and even more preferably 45 MPa or more, from the viewpoints of the mechanical strength of the cured product over a long period of time, adhesion to tooth structure, and durability.

[0162] Test Example 4: Measurement of Coating Thickness The labial surface of a bovine mandibular anterior tooth was polished with #80 silicon carbide paper (manufactured by Nihon Kenshi Co., Ltd.) under running water to obtain a sample with the flat surface of the dentin exposed. The obtained sample was further polished with #1000 silicon carbide paper (manufactured by Nihon Kenshi Co., Ltd.) under running water. After polishing, the surface was dried by air blowing. A piece of adhesive tape with a thickness of approximately 150 μm and a round hole with a diameter of 3 mm was attached to the smooth surface after drying to determine the adhesive area.

[0163] The dental adhesive compositions prepared in each Example and Comparative Example were applied to the inside of the round holes using an applicator brush (Fine <Silver> (manufactured by Kuraray Noritake Dental Co., Ltd.)), left to stand for 10 seconds, and then the entire dental adhesive composition in the round holes was dried with a mild air blow at low to medium pressure until the liquid surface stopped moving. To ensure complete drying, the air blow was carried out for 5 seconds or more. Subsequently, the applied dental adhesive composition was cured by irradiating it with light for 10 seconds using a dental visible light irradiator (Pencure 2000, manufactured by Morita Corporation) to form an adhesive layer.

[0164] The surface of the cured dental adhesive composition obtained was filled with a dental filling composite resin (manufactured by Kuraray Noritake Dental Co., Ltd., product name "Clearfil (registered trademark) Majesty (registered trademark) ES Flow") and covered with a release film (polyester). A slide glass was then placed on the release film and pressed against it to smooth the surface coated with the composite resin. The composite resin was then irradiated with light for 10 seconds using the "PenCure 2000" irradiator through the release film to cure the composite resin. The sample was then immersed in distilled water in a container and left in an incubator set at 37°C for 24 hours.

[0165] After leaving it for 24 hours, it was cut in half with a diamond cutter (Buchler, ISOMET1000, diamond cutting wheel used) so that the adhesive surface was exposed, and the shape of the sample was corrected with #80 silicon carbide paper (Nihon Kenshi Co., Ltd.) so that the observation surface could be placed parallel, and the observation surface was then precision-polished with lapping film (Sumitomo 3M) in the order of #1200, #3000, and #8000. The obtained polished sample was fixed to a sample stage with double-sided carbon tape (HIS2166, Hitachi High-Tech Fielding Co., Ltd.), and the coating thickness was measured at 3000x magnification using a scanning electron microscope (Hitachi High-Technologies Corporation, SU3500) in low vacuum mode. Specifically, as described above, a sample was cut in half to include the circular hole and expose the adhesive surface. To minimize variation in the thickness of the adhesive layer measured, 1 mm sections were excluded from each end of the adhesive layer filled in the 3 mm diameter circular hole. The average thickness of three randomly selected adhesive layer points within a 1 mm central range was measured using software as the coating thickness. Three samples were prepared, and the average value was taken as the coating thickness (n = 3). From the perspective of the abutment tooth shape, the coating thickness is preferably 12 μm or less, more preferably 11 μm or less, and even more preferably 10 μm or less.

[0166] Test Example 5 Measurement of Viscosity at 30°C with a Brookfield Viscometer 0.7 mL of the dental adhesive composition prepared in each of the above Examples or Comparative Examples was dropped into a rotational viscometer ("VISCOMETER TV-100" manufactured by Toki Sangyo Co., Ltd.), stirring was started at a measurement temperature of 30°C and a rotation speed of 10 rpm, and the viscosity at 30°C was measured 3 minutes after the start of stirring. Three measurement samples were prepared for each dental adhesive composition, and the average of these measured values ​​was taken as the viscosity of that dental adhesive composition at 30°C as measured by the Brookfield viscometer.

[0167]

[0168]

[0169]

[0170] As shown in Tables 1 and 2, the results of the dental adhesive compositions of the examples were as follows: The initial water absorption was 3.8% or less, and the durable water absorption was 7.9% or less. To enamel, the initial shear bond strength was 16 MPa or more, and the durable shear bond strength was 10 MPa or more. To dentin, the initial shear bond strength was 20 MPa or more, and the durable shear bond strength was 14 MPa or more. With regard to mechanical strength, the initial tensile strength was 42 MPa or more, and the durable tensile strength was 28 MPa. The coating thickness was 12 μm or less. The viscosity was 38 cps or less.

[0171] On the other hand, as shown in Table 3, among the comparative examples, Comparative Example 1, which did not contain a monomer (B-1) having three or more polymerizable groups per molecule, and Comparative Example 2, which did not contain a filler (F), had an initial tensile strength of less than 34 MPa and a durable tensile strength of less than 17 MPa. Comparative Example 3, which did not contain a volatile organic solvent (E), had a viscosity of 820 cps and a coating thickness of 40 μm. Comparative Examples 4 and 5, which did not contain a hydrophobic monomer (B-2), had initial water absorption of 6.5% or more and initial tensile strengths of 30 MPa or less. Comparative Example 6 had a high viscosity of 45 cps and a coating thickness of 14 μm, making it impossible to obtain a thin bond layer. Comparative Example 7, which did not contain a hydrophilic monomer (B-3), had an initial bond strength to enamel of 13 MPa, a durable bond strength of 9 MPa, a coating thickness of 18 μm, and a viscosity of 70 cps.

[0172] The dental adhesive composition of the present invention can be suitably used for filling purposes in dental treatment and for coating purposes for cavities and abutment teeth. In resin coating applications where thin films are required, the dental adhesive composition of the present invention has high mechanical strength over a long period of time even when the thickness of the film is 12 μm or less (preferably less than 10 μm), and therefore even if the layer of the cured product formed after an operation to volatilize the solvent component (such as air blowing) becomes thinner than expected due to differences in the thickness of the layer depending on the location due to the degree of air blowing, the mechanical strength of the cured product does not decrease over a long period of time, making it particularly advantageous in resin coating applications in that strict procedures are not required during use.