JP7493534B2 - Dental Composition - Google Patents

Description

The present invention relates to a dental composition for use in the dental medical field.

When treating dental caries and the associated defects, restorations using dental bonding material and dental composite resin have traditionally been commonly performed. Restorative treatment typically involves the following steps: First, the carious area is removed to form a cavity, and then dental bonding material is applied to the cavity, after which the area to which the dental bonding material has been applied is irradiated with visible light to harden it. Next, dental composite resin is filled on top of the hardened dental bonding material layer, and finally the filled dental composite resin is irradiated with visible light to harden it.

Dental composite resins have been widely used in recent years to replace the metal materials that were previously used, because they have aesthetic properties similar to those of natural teeth and excellent operability. Dental composite resins are generally composed of polymerizable monomers, polymerization initiators, and fillers. As polymerizable monomers, radically polymerizable polyfunctional (meth)acrylates have been commonly used from the viewpoints of safety in vivo and mechanical strength and abrasion resistance of the cured product. Among them, 2,2-bis[4-(3-methacryloyloxy-2-hydroxypropoxy)phenyl]propane (Bis-GMA) and 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)dimethacrylate (UDMA) are widely used. In addition, since Bis-GMA and UDMA have high viscosity alone, they are generally used by diluting them with a relatively low-viscosity polymerizable monomer such as triethylene glycol dimethacrylate (3G).

Although dental composite resins are now widely used in clinical practice, there is a need for improvements in the following areas. That is, it has been pointed out that there is still much room for improvement in areas such as the ease of handling the paste of the polymerizable composition used as dental composite resin, improving the bending strength, elastic modulus, and abrasion resistance of the cured product, reducing water absorption and discoloration, reducing polymerization shrinkage stress during curing, and achieving aesthetics similar to those of natural teeth.

In recent years, in particular, there is a strong desire to reduce polymerization shrinkage stress as much as possible, because it can lead to the occurrence of contraction gaps, which occur when dental composite resins peel off from the adhesive surface. The occurrence of contraction gaps can lead to secondary caries, pulp irritation, staining, and loss of restorations.

As a technique for reducing such polymerization shrinkage stress, a method of blending a polymer into a dental composition has been proposed. Patent Document 1 discloses a dental composition in which polymerization shrinkage stress is suppressed by using a dendritic polymer. Patent Document 2 discloses a dental composition in which polymerization shrinkage stress is suppressed by using a macrocyclic oligomer. Patent Document 3 discloses a particle composite material consisting of an organic binder and an inorganic filler, Patent Document 4 discloses a dental material consisting of a composition containing a metal fine powder, (meth)acrylic polymer particles, a polymerizable monomer component, and a polymerization catalyst, and Patent Document 5 discloses a dental filling and restoration kit characterized by being composed of a transparent external filler consisting of particles with a maximum diameter of 0.5 mm to 4.0 mm, and a dental polymerizable composition containing a radical polymerizable monomer and a photopolymerization initiator.

However, in Patent Document 1, the suppression of polymerization shrinkage stress is still insufficient, and since the molecular weight of the dendritic polymer is 20,000 or more, the viscosity of the composition is high, so the filling rate of the inorganic filler cannot be increased, and the strength is also insufficient. In Patent Document 2, the suppression of polymerization shrinkage stress is not sufficient even with the above means, and since the viscosity becomes high due to the inclusion of macrocyclic oligomers, which is a phenomenon similar to that of Patent Document 1, the filling rate of the inorganic filler cannot be increased, and the strength is also insufficient. Furthermore, in Patent Document 3, since a large amount of particle composite material with a large particle size is contained, the paste is rough, and since the particle composite material is treated with a polymerizable functional group, polymerization occurs during hardening, and the effect of reducing polymerization shrinkage stress is insufficient. In Patent Document 4, since most of the components in the dental material are (meth)acrylic polymer particles, the mechanical strength is insufficient, similar to Patent Document 3. In Patent Document 5, like Patent Document 3, the mechanical strength was insufficient and the particle size was too large, so that when a small amount of paste was used in clinical practice, the particles were sometimes contained in the paste and sometimes not, and the paste was not reliably effective.

JP 2014-24775 A JP 2012-188672 A JP 2002-256010 A Japanese Patent Application Laid-Open No. 11-29428 JP 2016-175851 A

As such, in the prior art, no dental composition was found that combines suppression of polymerization shrinkage stress with mechanical strength.

Therefore, the object of the present invention is to provide a dental composition that combines suppression of polymerization shrinkage stress with mechanical strength.

As a result of extensive research, the inventors have found that the above-mentioned problems can be solved by a dental composition which contains polymer particles and has a light diffusion degree D of the dental composition before hardening of a specific value or more, and after further research they have completed the present invention.

That is, the present invention provides
[1] A dental composition comprising a monomer (A), a polymerization initiator (B), polymer particles (C), and a filler (D) (excluding the polymer particles (C)), wherein the dental composition before curing has a light diffusion degree D represented by the following formula [I] of 0.10 or more;
D = ( _I20 /cos20° + _I70 /cos70°)/( _2I0 ) [I]
(In the formula, I represents the luminous intensity of light transmitted through the sample, and I ₀ , I ₂₀ and I ₇₀ represent the luminous intensity (light intensity) at 0 degrees, 20 degrees and 70 degrees, respectively, relative to the direction perpendicular to the sample plate (the direction of incidence of light).)
[2] The dental composition according to [1], wherein the average particle size of the polymer particles (C) is 0.5 μm to 50 μm;
[3] The dental composition according to [1] or [2], wherein the filler (D) is an inorganic filler;
[4] The dental composition according to any one of [1] to [3], wherein the polymer particles (C) are crosslinked polymer particles;
[5] The dental composition according to any one of [1] to [4], wherein the refractive index of the polymer particles (C) is 1.550 or more;
[6] The dental composition according to any one of [1] to [5], wherein the content of the polymer particles (C) is 0.1 to 20 parts by mass per 100 parts by mass of the dental composition;
[7] The dental composition according to any one of [1] to [6], wherein the content of the polymer particles (C) is 0.1 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the total amount of the monomer components;
[8] The dental composition according to any one of [1] to [7], wherein the polymer particles (C) are spherical;
[9] The dental composition according to any one of [1] to [8], wherein the refractive index difference between the polymer particles (C) and the total monomer mixture before curing is 0.020 or more;
[10] The dental composition according to any one of [1] to [9], wherein the polymer particles (C) are made of (meth)acrylic polymer particles or styrene polymer particles;
[11] The dental composition according to any one of [1] to [10], wherein the monomer (A) contains a monomer (A-1) having an acidic group;
[12] The dental composition according to any one of [1] to [11], wherein the monomer (A) includes a hydrophobic monomer (A-2) having no acidic group;
[13] The dental composition according to any one of [1] to [12], wherein the polymerization initiator (B) contains a water-insoluble photopolymerization initiator (B-2);
[14] The dental composition according to any one of [1] to [13], wherein the filler (D) contains an ultrafine inorganic filler having an average particle size of 1 nm or more and less than 0.1 μm;
[15] The dental composition according to any one of [1] to [13], wherein the filler (D) contains an inorganic filler having an average particle size of more than 1 μm and not more than 10 μm;
[16] A dental composite resin comprising the dental composition according to any one of [1] to [15];
[17] A self-adhesive dental composite resin comprising the dental composition according to any one of [1] to [15];
[18] A dental cement comprising the dental composition according to any one of [1] to [15];
Includes:

According to the present invention, there is provided a dental composition that achieves both suppression of polymerization shrinkage stress and mechanical strength, and a self-adhesive dental composite resin, dental composite resin, and dental cement using said composition. According to the present invention, there is also provided a dental composition that has light diffusibility and an appropriate cure depth, and a self-adhesive dental composite resin, dental composite resin, and dental cement using said composition.

FIG. 2 is an explanatory diagram of a method for measuring a light diffusion degree D according to the present invention.

The dental composition of the present invention comprises, as essential components, a monomer (A), a polymerization initiator (B), polymer particles (C), and a filler (D), and the dental composition before curing has a light diffusion index D represented by the following formula [I] of 0.10 or more.
D = ( _I20 /cos20° + _I70 /cos70°)/( _2I0 ) [I]
(In the formula, I represents the luminous intensity of light transmitted through the sample, and I ₀ , I ₂₀ and I ₇₀ represent the luminous intensity (light intensity) at 0 degrees, 20 degrees and 70 degrees, respectively, relative to the direction perpendicular to the sample plate (the direction of incidence of light).)

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, the upper and lower limits of the numerical ranges (contents of each component, values calculated from each component, and each physical property, etc.) can be combined as appropriate.

The reason why the dental composition of the present invention achieves both suppression of polymerization shrinkage stress and mechanical strength is unclear, but it is presumed to be as follows. That is, if the dental composition contains the polymer particles (C) and has a light diffusion degree D of 0.10 or more before curing, it is presumed that the stress generated during polymerization shrinkage is alleviated. The dental LED light irradiator used to cure the dental composition has a very strong linearity of light, and the curing depth is large, while stress accumulates at the interface between the dental composition and the adherend, which increases the polymerization shrinkage stress at the adhesive interface, leading to a decrease in adhesion and the occurrence of a contraction gap. In the present invention, the inclusion of the polymer particles (C) reduces the elastic modulus of the cured product, thereby suppressing the polymerization shrinkage stress generated in the dental composition itself. In addition, it is presumed that the dental composition has a specific light diffusion degree D, so that the light irradiated during curing is diffused and dispersed without concentrating at a specific location and applying polymerization shrinkage stress, thereby further reducing the polymerization shrinkage stress at the adhesive interface.

It is essential that the dental composition has a certain light diffusion property before hardening. Light diffusion property is a property in which light is refracted and reflected by the filler inside the material when it is incident on a translucent material such as a dental composite material, and the light is diffused in various directions. The reflected and diffused light observed has a color tone that reflects the color tone of the dental composite material and its background color. Therefore, if the light diffusion property is high, the effect of blurring the background color of the restoration and the contour between the restoration and natural teeth is also large, and therefore, it is considered that the color tone compatibility with natural teeth is high. As an index of this light diffusion property, the light diffusion degree D defined by the following formula [I] has been proposed. Figure 1 shows an explanatory diagram explaining formula [I].
D = ( _I20 /cos20° + _I70 /cos70°)/( _2I0 ) [I]
(In the formula, I represents the luminous intensity of light transmitted through the sample, and I ₀ , I ₂₀ and I ₇₀ represent the luminous intensity (light intensity) at 0 degrees, 20 degrees and 70 degrees, respectively, relative to the direction perpendicular to the sample plate (the direction of incidence of light).)

These luminous intensities (light intensity) can be measured using a variable angle photometer or a goniophotometer. The higher the value of this light diffusion degree D, the higher the light diffusion property of the cured product. As a variable angle photometer, a variable angle photometer such as the "GP-200" manufactured by Murakami Color Research Laboratory Co., Ltd. can be used.

According to the dental composition of the present invention, the light diffusion degree D of the dental composition before hardening is 0.10 or more, preferably 0.12 or more, more preferably 0.15 or more, even more preferably 0.20 or more, preferably 3.00 or less, more preferably 2.80 or less, even more preferably 2.50 or less, and most preferably 2.00 or less. If the light diffusion degree D value is less than 0.10, the light diffusion property of the dental composition becomes insufficient, and the effect of reducing the polymerization shrinkage stress becomes insufficient. On the other hand, if it is more than 3.00, the light diffusion property may be too strong and sufficient transparency may not be obtained. The dental composition of the present invention can also adjust the refractive index difference between the monomer component and the polymer particles (C) to make the light diffusion degree D within these preferred ranges. As a general rule, the smaller the refractive index difference, the smaller the light diffusion degree D tends to be, but the light diffusion degree D is also affected by factors other than the refractive index difference, such as the type or content of the monomer (A), the type or content of the polymer particles (C), and the compounding ratio of the monomer (A) and the polymer particles (C).

Below, we will explain each component used in the dental composition of the present invention.

[Monomer (A)]
The monomer (A) may be a monomer (A-1) having an acidic group, a hydrophobic monomer (A-2) having no acidic group, or a hydrophilic monomer (A-3) having no acidic group. The monomer (A) may be used alone or in combination of two or more kinds.
Monomer having an acidic group (A-1)
The monomer (A-1) having an acid group has an acid etching effect and a primer treatment effect, and is a component that imparts a demineralizing effect and a penetrating effect. The monomer (A-1) having an acid group is also polymerizable, and imparts a hardening effect. By including the monomer (A-1) having an acid group, the adhesiveness to tooth structure and the adhesive durability are improved.

Examples of monomers (A-1) having an acidic group include monomers having at least one acidic group such as a phosphate group, a pyrophosphate group, a thiophosphate group, a phosphonic acid group, a sulfonic acid group, or a carboxylic acid group, and at least one polymerizable group such as a (meth)acryloyl group, a vinyl group, or a styrene group. From the viewpoint of adhesion to tooth structure, a monomer containing a phosphate group is preferable. Specific examples of monomers (A-1) having an acidic group are listed below.

Examples of phosphate group-containing monomers 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)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)acryloyloxy Examples of the hydrogen phosphate include acryloyloxyicosyl dihydrogen phosphate, bis[2-(meth)acryloyloxyethyl]hydrogen phosphate, bis[4-(meth)acryloyloxybutyl]hydrogen phosphate, bis[6-(meth)acryloyloxyhexyl]hydrogen phosphate, bis[8-(meth)acryloyloxyoctyl]hydrogen phosphate, bis[9-(meth)acryloyloxynonyl]hydrogen phosphate, bis[10-(meth)acryloyloxydecyl]hydrogen phosphate, 1,3-di(meth)acryloyloxypropyl dihydrogen phosphate, 2-(meth)acryloyloxyethylphenyl hydrogen phosphate, 2-(meth)acryloyloxyethyl-2-bromoethyl hydrogen phosphate, bis[2-(meth)acryloyloxy-(1-hydroxymethyl)ethyl]hydrogen phosphate, and acid chlorides, alkali metal salts, and ammonium salts thereof.

Examples of pyrophosphate group-containing monomers 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 their acid chlorides, alkali metal salts, and ammonium salts.

Examples of thiophosphate group-containing monomers 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. Examples of suitable acryloyloxyalkyl phosphates include acryloyloxyalkyl 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.

Examples of phosphonic acid group-containing monomers 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.

Examples of sulfonic acid group-containing monomers include 2-(meth)acrylamide-2-methylpropanesulfonic acid, styrenesulfonic acid, and 2-sulfoethyl (meth)acrylate.

Carboxylic acid group-containing monomers include monomers having one carboxy group in the molecule and monomers having multiple carboxy groups in the molecule.

Monomers having one carboxy group in the molecule include (meth)acrylic acid, N-(meth)acryloylglycine, N-(meth)acryloylaspartic acid, O-(meth)acryloyltyrosine, N-(meth)acryloyltyrosine, N-(meth)acryloylphenylalanine, N-(meth)acryloyl-p-aminobenzoic acid, N-(meth)acryloyl-o-aminobenzoic acid, p-vinylbenzoic acid, 2-(meth)acryloyloxybenzoic acid. Examples of the aromatic compounds include acryloyloxybenzoic acid, 3-(meth)acryloyloxybenzoic acid, 4-(meth)acryloyloxybenzoic acid, N-(meth)acryloyl-5-aminosalicylic acid, N-(meth)acryloyl-4-aminosalicylic acid, 2-(meth)acryloyloxyethyl hydrogen succinate, 2-(meth)acryloyloxyethyl hydrogen phthalate, 2-(meth)acryloyloxyethyl hydrogen maleate, and acid halides thereof.

Examples of monomers having multiple carboxy groups in the 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 ...4-(meth)acryloyloxyhexane-1,1-dicarboxylic acid, 4-(meth)acryloyloxyhexane-1,1-dicarboxylic acid, 4-(meth)acryloyloxyhexane-1,1-dicarboxylic acid, 4-(meth)acryloyloxyhexane-1,1-dicarboxylic acid, 4-(meth)acryloyloxyhexane-1,1-dicarboxylic acid, 4-(meth)acryloyloxyhexane-1,1-dicarboxylic acid, 4-(meth)acryloyloxyhexane-1,1-dicarboxylic acid, 4-(meth)acryloyloxyhexane-1,1-dicarboxylic acid, 4-(meth)acryloyloxyhexane-1,1-dicarboxylic acid, 4-(meth)acryloyl Examples of the acid anhydride and acid halide include 4-(meth)acryloyloxyethyl trimellitate, 4-(meth)acryloyloxyethyl trimellitate anhydride, 4-(meth)acryloyloxybutyl trimellitate, 4-(meth)acryloyloxyhexyl trimellitate, 4-(meth)acryloyloxydecyl trimellitate, 2-(meth)acryloyloxyethyl-3'-(meth)acryloyloxy-2'-(3,4-dicarboxybenzoyloxy)propyl succinate, and acid anhydrides or acid halides thereof.

Among these monomers (A-1) having an acidic group, phosphate or pyrophosphate group-containing (meth)acrylic monomers are preferred because they exhibit superior adhesion to tooth structure, and phosphate group-containing (meth)acrylic monomers are more preferred. Among these, divalent phosphate group-containing (meth)acrylic monomers having an alkyl or alkylene group with 6 to 20 carbon atoms as the main chain in the molecule are even more preferred because they exhibit high demineralization properties in the absence of organic solvents and high adhesion, and divalent phosphate group-containing (meth)acrylic monomers having an alkylene group with 8 to 12 carbon atoms as the main chain in the molecule, such as 10-methacryloyloxydecyl dihydrogen phosphate, are particularly preferred.

The monomer (A-1) having an acidic group may be used alone or in combination of two or more types. When the content of the monomer (A-1) having an acidic group is either too high or too low, the adhesion may decrease. Therefore, the content of the monomer (A-1) having an acidic group is preferably in the range of 1 to 50 parts by mass, more preferably in the range of 3 to 40 parts by mass, and even more preferably in the range of 5 to 30 parts by mass, per 100 parts by mass of the total amount of the monomer components in the dental composition.

Hydrophobic monomer (A-2) having no acidic group
The hydrophobic monomer (A-2) having no acidic group (hereinafter referred to as hydrophobic monomer (A-2)) improves the mechanical strength, handling properties, etc. of the dental composition. A radical monomer having no acidic group and a polymerizable group is preferable, and from the viewpoint of ease of radical polymerization, the polymerizable group is more preferably a (meth)acrylic group and/or a (meth)acrylamide group. The hydrophobic monomer (A-2) means a monomer having no acidic group and a solubility in water at 25° C. of less than 10% by mass, and examples of the monomer include crosslinkable monomers such as bifunctional monomers of aromatic compounds, bifunctional monomers of aliphatic compounds, and trifunctional or higher monomers.

Examples of aromatic bifunctional 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, phenyl)propane, 2,2-bis(4-(meth)acryloyloxydipropoxyphenyl)propane, 2-(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, 2,2-bis[4-(3-methacryloyloxy-2-hydroxypropoxy)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 is 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.

Examples of aliphatic compound-based bifunctional monomers 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, 1,10-decanediol di(meth)acrylate, 1,2-bis(3-methacryloyloxy-2-hydroxypropoxy)ethane, 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)di(meth)acrylate, N-methacryloyloxyethylacrylamide, and N-methacryloyloxypropylamide. Among these, triethylene glycol diacrylate, triethylene glycol dimethacrylate (commonly known as "3G"), neopentyl glycol di(meth)acrylate, 1,2-bis(3-methacryloyloxy-2-hydroxypropoxy)ethane, 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)dimethacrylate (commonly known as "UDMA"), 1,10-decanediol dimethacrylate (commonly known as "DD"), 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)dimethacrylate, and N-methacryloyloxyethylacrylamide (commonly known as "MAEA") are preferred.

Examples of trifunctional or higher monomers include trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolmethane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, 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, etc. Among these, N,N-(2,2,4-trimethylhexamethylene)bis[2-(aminocarboxy)propane-1,3-diol]tetramethacrylate is preferred.

Among the above hydrophobic monomers (A-2), aromatic compound-based bifunctional monomers and aliphatic compound-based bifunctional monomers are preferably used in terms of ease of adjusting the light diffusion degree D, mechanical strength, and ease of handling. Bis-GMA and D-2.6E are preferred as aromatic compound-based bifunctional monomers. Glycerol di(meth)acrylate, 3G, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, DD, 1,2-bis(3-methacryloyloxy-2-hydroxypropoxy)ethane, UDMA, and MAEA are preferred as aliphatic compound-based bifunctional monomers.

Among the above hydrophobic monomers (A-2), Bis-GMA, D-2.6E, 3G, UDMA, DD, and MAEA are more preferred, with D-2.6E, DD, and MAEA being even more preferred, from the standpoints of the ease of adjusting the light diffusion degree D, the initial adhesive strength to tooth substance, adhesive durability, and mechanical strength.

The hydrophobic monomer (A-2) may be used alone or in combination of two or more. If the content of the hydrophobic monomer (A-2) is too high, the composition may have a reduced ability to penetrate into the tooth structure, resulting in a reduced adhesive strength, whereas if the content is too low, the effect of improving mechanical strength may not be sufficiently obtained. Therefore, the hydrophobic monomer (A-2) is preferably in the range of 20 to 99 parts by mass, more preferably in the range of 40 to 99 parts by mass, and even more preferably in the range of 60 to 99 parts by mass, relative to 100 parts by mass of the total amount of the monomer components in the dental composition.

Hydrophilic monomer having no acidic group (A-3)
The dental composition of the present invention preferably further contains a hydrophilic monomer (A-3) having no acidic group (hereinafter referred to as hydrophilic monomer (A-3)). The hydrophilic monomer (A-3) promotes the penetration of the components of the dental composition into the tooth structure, and also penetrates into the tooth structure itself to adhere to the organic component (collagen) in the tooth structure. As the hydrophilic monomer (A-3), a radical monomer having no acidic group and a polymerizable group is preferable, and from the viewpoint of ease of radical polymerization, the polymerizable group is more preferably a (meth)acrylic group and/or a (meth)acrylamide group. The hydrophilic monomer (A-3) means a monomer having no acidic group and a solubility in water at 25° C. of 10% by mass or more, preferably a monomer having a solubility of 30% by mass or more, and more preferably a monomer capable of dissolving in water at any ratio at 25° C. As the hydrophilic monomer (A-3), those having a hydrophilic group such as a hydroxyl group, an oxymethylene group, an oxyethylene group, an oxypropylene group, or an amide group are preferred. For example, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 1,3-dihydroxypropyl (meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, 2-((meth)acryloyloxy)ethyltrimethylammonium chloride, polyethylene glycol di(meth)acrylate (those having 9 or more oxyethylene groups) are preferred. ), and other hydrophilic monofunctional (meth)acrylate monomers; and monofunctional (meth)acrylamide monomers, such as N-methylol(meth)acrylamide, 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.

Among these hydrophilic monomers (A-3), from the viewpoint of adhesion to tooth structure, 2-hydroxyethyl (meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, diacetone (meth)acrylamide and hydrophilic monofunctional (meth)acrylamide monomers are preferred, and 2-hydroxyethyl (meth)acrylate, N,N-dimethylacrylamide and N,N-diethylacrylamide are more preferred. One type of hydrophilic monomer (A-3) may be used alone, or two or more types may be used in combination.

If the content of hydrophilic monomer (A-3) in the present invention is too low, the effect of improving adhesive strength may not be sufficiently obtained, and if it is too high, the mechanical strength may decrease. Therefore, the content of hydrophilic monomer (A-3) is preferably in the range of 0 to 50 parts by mass, more preferably in the range of 0 to 40 parts by mass, and even more preferably in the range of 0 to 30 parts by mass, relative to 100 parts by mass of the total amount of the monomer components in the dental composition. The content of hydrophilic monomer (A-3) may be 0 parts by mass.

[Polymerization initiator (B)]
The polymerization initiator (B) is largely classified into a photopolymerization initiator and a chemical polymerization initiator, and the photopolymerization initiator is further classified into a water-soluble photopolymerization initiator (B-1) and a water-insoluble photopolymerization initiator (B-2). As the polymerization initiator (B), only the water-soluble photopolymerization initiator (B-1) may be used, only the water-insoluble photopolymerization initiator (B-2) may be used, or the water-soluble photopolymerization initiator (B-1) and the water-insoluble photopolymerization initiator (B-2) may be used in combination.

Water-soluble photopolymerization initiator (B-1)
The water-soluble photopolymerization initiator (B-1) improves polymerization curing at the hydrophilic tooth surface interface, and can realize high adhesive strength. The solubility of the water-soluble photopolymerization initiator (B-1) is 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. If the solubility is less than 10 g/L, the water-soluble photopolymerization initiator (B-1) does not dissolve sufficiently in water in the tooth substance at the adhesive interface, and the polymerization promotion effect is difficult to be exhibited.

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

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.

Examples of the water-soluble acylphosphine oxides include acylphosphine oxides represented by the following general formula (1) or (2).

In formulas (1) and (2), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are each independently a linear or branched alkyl group having 1 to 4 carbon atoms or a halogen atom, in formula (1), M is a hydrogen ion, an alkali metal ion, an alkaline earth metal ion, a magnesium ion, a pyridinium ion (the pyridine ring may have a substituent), or an ammonium ion represented by HN ⁺ R ⁸ R ⁹ R ¹⁰ (in which R ⁸ , R ⁹ , and R ¹⁰ are each independently an organic group or a hydrogen atom), and n is 1 or 2. In formula (2), X is a linear or branched alkylene group having 1 to 4 carbon atoms, and R ⁷ is represented by -CH(CH ₃ )COO(C ₂ H ₄ O) _p CH ₃ , where p is an integer from 1 to 1,000.

The alkyl group of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ is not particularly limited as long as it is a straight-chain or branched-chain group having 1 to 4 carbon atoms, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a 2-methylpropyl group, and a tert-butyl group. The alkyl group of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ is preferably a straight-chain alkyl group having 1 to 3 carbon atoms, more preferably a methyl group or an ethyl group, and even more preferably a methyl group. The alkylene group of X includes a methylene group, an ethylene group, an n-propylene group, an isopropylene group, and an n-butylene group. The alkylene group of X is preferably a straight-chain alkylene group having 1 to 3 carbon atoms, more preferably a methylene group or an ethylene group, and even more preferably a methylene group.

In the case where M is a pyridinium ion, examples of the substituent on the pyridine ring include halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms), carboxy groups, linear or branched acyl groups having 2 to 6 carbon atoms, linear or branched alkyl groups having 1 to 6 carbon atoms, and linear or branched alkoxy groups having 1 to 6 carbon atoms. M is preferably an alkali metal ion, an alkaline earth metal ion, a magnesium ion, a pyridinium ion (the pyridine ring may have a substituent), or an ammonium ion represented by HN ⁺ R ⁸ R ⁹ R ¹⁰ (wherein the symbols have the same meanings as above). Examples of the alkali metal ion include a lithium ion, a sodium ion, a potassium ion, a rubidium ion, and a cesium ion. Examples of the alkaline earth metal ion include a calcium ion, a strontium ion, a barium ion, and a radium ion. Examples of the organic groups of ^{R 8} , R ⁹ , and R ¹⁰ include the same ones as the substituent on the pyridine ring (excluding halogen atoms).

Among these, compounds in which R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ in formulas (1) and (2) are all methyl groups are particularly preferred in terms of storage stability and color stability in the composition. On the other hand, examples of M ⁿ⁺ include Li ⁺ , Na ⁺ , K ⁺ , Ca ²⁺ , Mg ²⁺ and ammonium ions derived from various amines, and examples of amines include ammonia, trimethylamine, diethylamine, dimethylaniline, ethylenediamine, triethanolamine, N,N-dimethylamino methacrylate, N,N-dimethylaminobenzoic acid and its alkyl esters, N,N-diethylaminobenzoic acid and its alkyl esters, N,N-bis(2-hydroxyethyl)-p-toluidine, etc. For ^R7 , from the viewpoint of adhesiveness, p is preferably 1 or more, more preferably 2 or more, even more preferably 3 or more, and particularly preferably 4 or more; it is preferably 1,000 or less, more preferably 100 or less, even more preferably 75 or less, and particularly preferably 50 or less.

Among these water-soluble acylphosphine oxides, particularly preferred are the compound represented by general formula (1) in which M is Li, and the compound represented by general formula (2) synthesized from polyethylene glycol methyl ether methacrylate in which the portion corresponding to the group represented by ^R7 has a molecular weight of 950. In these compounds, ^R1 , ^R2 , and ^R3 in general formula (1) and ^R1 , ^R2 , ^R3 , ^R4 , ^R5 , and ^R6 in general formula (2) are as described above.

Water-soluble acylphosphine oxides having such a structure can be synthesized according to known methods, and some of them are also available as commercially available products. For example, they can be synthesized by the method disclosed in non-patent literature such as Chem. Commun., 2018, 54(8), 920-923, JP-A-57-197289, and WO 2014/095724. The water-soluble photopolymerization initiator (B-1) may be used alone or in combination of two or more kinds.

The water-soluble photopolymerization initiator (B-1) may be dissolved in the water on the surface of the tooth substance (wet body) and may selectively enhance the polymerization hardening property at the adhesive interface and inside the resin-impregnated layer, and may be dissolved in the dental composition or dispersed in powder form in the composition.

When dispersing the water-soluble photopolymerization initiator (B-1) in powder form, if the average particle size is too large, it will tend to settle, so it is preferably 500 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less. On the other hand, if the average particle size is too small, the specific surface area of the powder will be too large, reducing the amount that can be dispersed in the composition, so it is preferably 0.01 μm or more. In other words, the average particle size of the water-soluble photopolymerization initiator (B-1) is preferably in the range of 0.01 to 500 μm, more preferably in the range of 0.01 to 100 μm, and even more preferably in the range of 0.01 to 50 μm.

The average particle diameter of each water-soluble photopolymerization initiator (B-1) powder can be calculated as the volume average particle diameter after image analysis using image analysis particle size distribution measurement software (Mac-View; manufactured by Mountec Co., Ltd.) based on electron microscope photographs of 100 or more particles.

When the water-soluble photopolymerization initiator (B-1) is dispersed in powder form, the shape of the initiator may be, but is not particularly limited to, various shapes such as spherical, needle-like, plate-like, and crushed. The water-soluble photopolymerization initiator (B-1) can be prepared by conventionally known methods such as a pulverization method, a freeze-drying method, and a reprecipitation method. From the viewpoint of the average particle size of the obtained powder, the freeze-drying method and the reprecipitation method are preferred, and the freeze-drying method (Method 1) is more preferred.

From the viewpoint of the hardening property of the dental composition obtained, the content of the water-soluble photopolymerization initiator (B-1) is preferably 0.01 to 20 parts by mass relative to 100 parts by mass of the total amount of the monomer components in the dental composition, and from the viewpoint of high initial adhesive strength and adhesive durability, and reduction of polymerization shrinkage stress, the content is more preferably 0.05 to 10 parts by mass, and even more preferably 0.1 to 5 parts by mass. If the content of the water-soluble photopolymerization initiator (B-1) is less than 0.01 parts by mass, polymerization at the adhesive interface may not proceed sufficiently, resulting in a decrease in adhesive strength. On the other hand, if the content of the water-soluble photopolymerization initiator (B-1) is more than 20 parts by mass, if the polymerization performance of the water-soluble photopolymerization initiator (B-1) is low, sufficient adhesive strength may not be obtained, and further dissolution, dispersion, and diffusion in the dental composition may be insufficient.

Non-water-soluble photopolymerization initiator (B-2)
From the viewpoint of curability, the dental composition of the present invention may contain, in addition to the water-soluble photopolymerization initiator (B-1), a water-insoluble photopolymerization initiator (B-2) having a solubility in water at 25° C. of less than 10 g/L (hereinafter referred to as water-insoluble photopolymerization initiator (B-2)). As the water-insoluble photopolymerization initiator (B-2) used in the present invention, a known photopolymerization initiator can be used. The water-insoluble photopolymerization initiator (B-2) may be used alone or in combination of two or more kinds.

Examples of non-water-soluble photopolymerization initiators (B-2) include (bis)acylphosphine oxides, thioxanthones, ketals, α-diketones, coumarins, anthraquinones, benzoin alkyl ether compounds, and α-aminoketone compounds other than the water-soluble photopolymerization initiators (B-1).

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.

Examples of the thioxanthones include thioxanthone, 2-chlorothioxanthen-9-one, etc.

Examples of the ketals include benzyl dimethyl ketal and benzyl diethyl ketal.

Examples of the α-diketones include diacetyl, benzyl, dl-camphorquinone, 2,3-pentadione, 2,3-octadione, 9,10-phenanthrenequinone, 4,4'-oxybenzyl, acenaphthenequinone, etc. Among these, dl-camphorquinone is particularly preferred because it has a maximum absorption wavelength in the visible light region.

Examples of the coumarin compounds 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-bromocoumarin, 3,3'-carbonylbiscoumarin, 3-benzoyl-7-dimethylaminocoumarin, 3-benzoylbenzo[f]coumarin, and 3-carboxycoumarin. phosphorus, 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-di phenylaminocinnamoyl)coumarin, 3-[(3-dimethylbenzothiazol-2-ylidene)acetyl]coumarin, 3-[(1-methylnaphtho[1,2-d]thiazol-2-ylidene)acetyl]coumarin, 3,3'-carbonylbis(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 phosphorus, 3,3'-carbonylbis(7-dibutylaminocoumarin), 3,3'-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, 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, and the like, which are described in JP-A-9-3109 and JP-A-10-245525, are included.

Among the above-mentioned coumarin compounds, 3,3'-carbonylbis(7-diethylaminocoumarin) and 3,3'-carbonylbis(7-dibutylaminocoumarin) are particularly preferred.

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

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

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

Among these water-insoluble photopolymerization initiators (B-2), it is preferable to use at least one selected from the group consisting of (bis)acylphosphine oxides, α-diketones, and coumarin compounds. This results in a dental composition that has excellent photocurability in the visible and near-ultraviolet regions and exhibits sufficient photocurability whether a halogen lamp, a light-emitting diode (LED), or a xenon lamp is used as a light source.

The content of the water-insoluble photopolymerization initiator (B-2) is not particularly limited, but from the viewpoint of the curability of the resulting composition, the content of the water-insoluble photopolymerization initiator (B-2) is preferably in the range of 0.01 to 10 parts by mass, more preferably in the range of 0.05 to 7 parts by mass, and even more preferably in the range of 0.1 to 5 parts by mass, relative to 100 parts by mass of the total amount of the monomer components in the dental composition. If the content of the water-insoluble photopolymerization initiator (B-2) exceeds 10 parts by mass, if the polymerization performance of the polymerization initiator itself is low, there is a risk that sufficient adhesive strength cannot be obtained, and further there is a risk of precipitation from the dental composition.

In the present invention, the mass ratio of the water-soluble photopolymerization initiator (B-1) to the water-insoluble photopolymerization initiator (B-2) [(B-1):(B-2)] is preferably 10:1 to 1:10, more preferably 7:1 to 1:7, even more preferably 5:1 to 1:5, and most preferably 3:1 to 1:3. If the water-soluble photopolymerization initiator (B-1) is blended in a mass ratio of more than 10:1, the hardening property of the dental composition itself may decrease, making it difficult to develop high adhesive strength. On the other hand, if the water-insoluble photopolymerization initiator (B-2) is blended in a mass ratio of more than 1:10, the hardening property of the dental composition itself may be increased, but the polymerization promotion at the adhesive interface may be insufficient, making it difficult to develop high adhesive strength.

[Chemical Polymerization Initiator]
The dental composition of the present invention may further contain a chemical polymerization initiator, and an organic peroxide is preferably used. The organic peroxide used as the above-mentioned chemical polymerization initiator is not particularly limited, and any known organic peroxide can be used. Representative organic peroxides include, for example, ketone peroxides, hydroperoxides, diacyl peroxides, dialkyl peroxides, peroxyketals, peroxyesters, and peroxydicarbonates. Specific examples of these organic peroxides include those described in International Publication No. 2008/087977.

[Polymer particles (C)]
The polymer particles (C) are used in the dental composition of the present invention in order to achieve both suppression of polymerization shrinkage stress and mechanical strength.

In the present invention, the polymer particles (C) are particles obtained by polymerizing a monomer and do not dissolve in the dental composition, and generally known particles can be used without any restrictions. The polymer particles (C) in the present invention do not dissolve in the dental composition and exist as particles, thereby exerting effects such as reducing polymerization shrinkage stress. In addition, although the cure depth is generally significantly reduced when a dental composition is given light diffusion properties, by using the polymer particles (C), in addition to achieving both the effect of reducing polymerization shrinkage stress and high mechanical strength, a significant decrease in the cure depth is suppressed, and a dental composition having a suitable cure depth can be obtained.

From the standpoints of solubility in the dental composition and strength, the polymer particles (C) used in the present invention are preferably crosslinked polymer particles, which are polymers of monomers including monomers having two or more polymerizable groups.

The monomer for synthesizing the polymer particles (C) used in the present invention includes vinyl monomers (compounds having an ethylenic double bond) that are commonly used in the synthesis of ordinary polymers. In the present invention, the desired light diffusion degree D can be prepared by using the polymer particles (C) using a vinyl monomer. Specific examples of the vinyl monomer include conjugated diene monomers; aromatic vinyl monomers (e.g., styrene monomers, etc.); heterocyclic vinyl monomers; vinyl ester monomers; olefin monomers; vinyl ether monomers; ethylenically unsaturated carboxylic acid monomers; cyanide vinyl monomers; (meth)acrylic monomers (e.g., (meth)acrylamide monomers; (meth)acrylic acid alkyl ester monomers, etc.); carboxylic acid vinyl ester monomers; amino group-containing ethylenic monomers; vinyl halides; and sulfonic acid group- or phosphoric acid group-containing monomers (sulfonic acid group- or phosphoric acid group-containing vinyl monomers). The polymer particles (C) may be blended alone or in combination of two or more kinds. As the polymer particles (C) synthesized from these monomers, (meth)acrylic polymer particles and styrene polymer particles are preferred, and crosslinked (meth)acrylic polymer particles and crosslinked polystyrene particles are more preferred, in particular from the viewpoint of ease of adjusting the desired light diffusion degree D.

Examples of the (meth)acrylic polymer particles include polymer particles obtained by polymerization of a (meth)acrylic monomer (a monomer having a (meth)acrylic skeleton, such as a (meth)acrylic acid ester monomer, a (meth)acrylamide monomer, or (meth)acrylonitrile), or polymer particles obtained by copolymerization of a (meth)acrylic monomer with a vinyl monomer copolymerizable therewith, which contains a (meth)acrylic monomer component as the predominant component, with the content of the (meth)acrylic monomer being at least 25 mol % or more, and preferably 40 mol % or more, of all components constituting the polymer particles. Examples of the (meth)acrylic polymer particles include (meth)acrylic acid ester polymer particles obtained by polymerization of one or two to four types of (meth)acrylic acid C ₁ -C ₁₂ alkyl esters, (meth)acrylic butadiene copolymer particles obtained by copolymerization of a (meth)acrylic monomer and butadiene, (meth)acrylonitrile polymer particles obtained by homopolymerization of (meth)acrylonitrile, and (meth)acrylic styrene copolymer particles obtained by polymerization of a (meth)acrylic monomer and a styrene monomer. As the (meth)acrylic polymer particles, (meth)acrylic acid ester polymer particles are preferred.

Examples of styrene polymer particles include polymer particles of a styrene monomer (a monomer having a styrene skeleton) or polymer particles obtained by copolymerization of a styrene monomer with a vinyl monomer copolymerizable therewith, which contain a styrene monomer component as the most abundant component, and the content of the styrene monomer component is at least 25 mol% or more, preferably 40 mol% or more, of all components constituting the polymer particles. Examples of styrene polymer particles include polystyrene particles obtained by homopolymerization of styrene, styrene-vinyl copolymer particles, styrene-butadiene copolymer particles, and styrene-acrylic copolymer particles, and the like, with polystyrene particles and styrene-vinyl copolymer particles being preferred.

The polymer particles (C) in the present invention can usually be obtained by suspension polymerization or emulsion polymerization, and organic fillers (polymer particles obtained by polymerizing a monomer and then pulverizing it) can also be used. These polymers may also be modified by introducing a carboxyl group or the like into the polymer. From the viewpoint of light diffusion, polymer particles (C) obtained by suspension polymerization or emulsion polymerization are preferred.

The (meth)acrylic monomer (monomer having a (meth)acrylic skeleton) used in the synthesis of the (meth)acrylic polymer particles includes at least one (meth)acrylic monomer selected from the group consisting of (meth)acrylic acid or a salt thereof, an aliphatic (meth)acrylic acid ester, an aromatic (meth)acrylic acid ester, a (meth)acrylamide monomer, and (meth)acrylonitrile, with (meth)acrylic acid, an aliphatic (meth)acrylic acid ester, and an aromatic (meth)acrylic acid ester being preferred.

Monomers other than the (meth)acrylic component used in the synthesis of the (meth)acrylic polymer particles include vinyl monomers other than the (meth)acrylic monomers that are copolymerizable with the (meth)acrylic monomers. Examples of vinyl monomers other than the (meth)acrylic monomers that are copolymerizable with the (meth)acrylic monomers include styrene monomers (e.g., styrene, α-methylstyrene, divinylbenzene, etc.), vinyl chloride, vinyl acetate, itaconic acid, crotonic acid, maleic acid, fumaric acid, ethylene, conjugated dienes having 4 to 8 carbon atoms (e.g., 1,3-butadiene, isoprene, and chloroprene), etc., with styrene monomers being preferred. (Meth)acrylic copolymer particles obtained by polymerization of these with one or two to four (meth)acrylic monomers are preferred.

The styrene monomer used in the synthesis of the styrene polymer particles is not particularly limited as long as it is a compound having styrene as a basic skeleton, and examples thereof include styrene; compounds having two or more vinyl groups on the benzene ring of the styrene skeleton, such as divinylbenzene; styrene compounds having one or more halogen atoms or alkyl groups having 1 to 3 carbon atoms as substituents on the benzene ring of the styrene skeleton, such as vinyltoluene, ethylvinylbenzene, bromostyrene, and chlorostyrene; and styrene compounds having alkyl groups having 1 to 3 carbon atoms as substituents on the vinyl group of the styrene skeleton, such as α-methylstyrene and α-ethylstyrene. Styrene and divinylbenzene are preferred because they are easy to adjust to the desired light diffusion degree D.

Preferred monomers other than styrene-based monomers that are copolymerizable with styrene-based monomers include (meth)acrylic acid or its salts, at least one (meth)acrylic monomer selected from the group consisting of aliphatic (meth)acrylic acid esters, aromatic (meth)acrylic acid esters, (meth)acrylamide monomers and (meth)acrylonitrile, vinyl chloride, vinyl acetate, itaconic acid, crotonic acid, maleic acid, fumaric acid, ethylene, conjugated dienes having 4 to 8 carbon atoms (e.g., 1,3-butadiene, isoprene and chloroprene), etc., with (meth)acrylic acid or its salts, aliphatic (meth)acrylic acid esters, aromatic (meth)acrylic acid esters and (meth)acrylamide-based monomers being preferred.

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, acrylonitrile-styrene-butadiene copolymer, etc. These may be used alone or as a mixture of two or more.

Commercially available products may be used as the polymer particles (C). Examples of commercially available products include Techpolymer (registered trademark) "SBX series" (SBX-4, SBX-6, SBX-8, SBX-12 (crosslinked polystyrene particles, refractive index: 1.59, average particle size: 12 μm)) manufactured by Sekisui Chemical Co., Ltd., Techpolymer (registered trademark) "MSX series" (crosslinked methyl methacrylate-styrene copolymer particles, refractive index: 1.495 to 1.595, average particle size: 5 μm or more), Techpolymer (registered trademark) "MBX series" (crosslinked polymethyl methacrylate particles, refractive index: 1.595 to 1.595, average particle size: 5 μm or more), and Examples of such fine particles include Techpolymer (registered trademark) "SMX series" (copolymer crosslinked fine particles of methyl methacrylate and styrene, refractive index: 1.49, average particle size: 12 μm), Techpolymer (registered trademark) "SMX series" (copolymer crosslinked fine particles of methyl methacrylate and styrene, refractive index: 1.495 to 1.595, average particle size: 5 μm or more), Nemoto Specialty Chemical Industry Co., Ltd.'s "Lumipearl" series, Nippon Shokubai Co., Ltd.'s "Eposter (registered trademark) MA" series and "Eposter (registered trademark) MA" series, and among these, those with a refractive index of 1.550 or more are preferred from the standpoint of the effect of reducing polymerization shrinkage stress, etc.

From the viewpoint of expressing light diffusion properties, the refractive index of the polymer particles (C) is preferably different from the refractive index of both the monomer component and the filler (D), and more preferably is greater than the refractive index of both the monomer component and the filler (D) before curing. Specifically, the refractive index of the polymer particles (C) is preferably 1.550 or more, more preferably 1.555 or more, and even more preferably 1.560 or more. Also, it is preferably 1.800 or less, more preferably 1.700 or less, and even more preferably 1.650 or less. If the refractive index of the polymer particles (C) is less than 1.550, the light diffusion properties are insufficient, and the effect of reducing the polymerization shrinkage stress may be small. On the other hand, if it exceeds 1.800, the transparency of the dental composition may be significantly reduced. Furthermore, from the viewpoint of the light diffusion property before hardening of the dental composition, the refractive index difference between the polymer particles (C) and the total monomer mixture (monomer components) before hardening is preferably 0.020 or more, more preferably 0.025 or more, and even more preferably 0.030 or more, and the refractive index difference between the polymer particles (C) and the filler (D) is preferably 0.005 or more, more preferably 0.010 or more, and even more preferably 0.015 or more. When the refractive index difference is within the above range, it is easier to adjust the desired light diffusion degree D in combination with other components such as the content of the polymer particles (C).

In this specification, the refractive index of the polymer particles (C), filler (D), and monomer components can be measured with an Abbe refractometer. The refractive index of the polymer particles (C) and filler (D) can be measured by partially modifying JIS K 0062:1992. Specifically, the refractive index can be measured by an immersion method at 23°C using an Abbe refractometer and sodium D line as a light source. As for the liquid, two or more liquids with refractive indices close to the expected refractive index of the filler (polymer particles (C) and filler (D)) of the sample are combined to prepare multiple liquids with different refractive indices. The sample is suspended in each liquid in an atmosphere of 23°C, and the liquid that appears most transparent when observed with the naked eye is selected. The refractive index of the liquid is taken as the refractive index of the sample, and the refractive index of the liquid is measured with an Abbe refractometer. Examples of liquids that can be used include diiodomethane, 1-bromonaphthalene, methyl salicylate, dimethylformamide, 1-pentanol, etc., in which sulfur is dissolved. In the case of monomer components, the measurement can be performed in accordance with JIS K 0062:1992, specifically, using an Abbe refractometer with sodium D line as a light source in an atmosphere of 23°C. In the case of monomer components before curing, the measurement can be performed in liquid form. In the case of monomer components after curing, the monomer components are formed into a cured plate of a certain size and then measured. Usable liquids include diiodomethane, 1-bromonaphthalene, methyl salicylate, dimethylformamide, 1-pentanol, etc., in which sulfur is dissolved.

The shape of the polymer particles (C) may be amorphous or spherical. From the viewpoint of reducing polymerization shrinkage stress, it is preferable to use spherical polymer particles as the polymer particles (C). Furthermore, when the spherical polymer particles are used, there is an advantage that the dental composition of the present invention has excellent fluidity. Here, spherical polymer particles are polymer particles that are photographed with an electron microscope, and the particles observed within a unit field of view are rounded, and the average uniformity obtained by dividing the particle diameter in a direction perpendicular to the maximum diameter by the maximum diameter is 0.6 or more.

The average particle size of the polymer particles (C) is preferably 0.5 μm or more, more preferably 0.7 μm or more, even more preferably 1.0 μm or more, particularly preferably 1.5 μm or more, and preferably 50 μm or less, more preferably 30 μm or less, even more preferably 20 μm or less, particularly preferably 10 μm or less. If the average particle size is less than 0.5 μm, the viscosity of the dental composition may increase significantly and the mechanical strength may decrease. On the other hand, if the average particle size exceeds 50 μm, the light diffusion effect of the polymer particles (C) may decrease, and the effect of reducing polymerization shrinkage stress may decrease.

In this specification, the average particle size of the polymer particles (C) can be determined by a laser diffraction scattering method or by observing the particles under an electron microscope. Specifically, the laser diffraction scattering method is a convenient method for measuring the particle size of particles of 0.1 μm or more. 0.1 μm is a value measured by the laser diffraction scattering method.

Specifically, the laser diffraction scattering method can be used, for example, with a laser diffraction particle size distribution measuring device (SALD-2300: manufactured by Shimadzu Corporation) to measure on a volumetric basis using a 0.2% aqueous solution of sodium hexametaphosphate as the dispersion medium.

The content of the polymer particles (C) used in the present invention is not particularly limited, and is preferably 0.1 parts by mass or more and 20 parts by mass or less, more preferably 0.5 parts by mass or more and 15 parts by mass or less, and even more preferably 0.8 parts by mass or more and 10 parts by mass or less, in 100 parts by mass of the dental composition. If the content is less than 0.1 parts by mass, it is difficult to adjust to a predetermined light diffusion degree D, and the light diffusion effect is insufficient, so that the reduction of polymerization shrinkage stress may not be sufficient. On the other hand, if the content exceeds 20 parts by mass, a hardened product of the dental composition having high mechanical strength may not be obtained. The content of the polymer particles (C) is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less, relative to the total amount of the monomer components of 100 parts by mass. By blending the polymer particles (C) in an amount less than the content of the monomer components, a predetermined light diffusion degree D can be obtained. Adjustment of the refractive index difference between the monomer component and the polymer particles (C) also has an effect in obtaining a predetermined light diffusion degree D. The content of the polymer particles (C) is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, and is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, relative to 100 parts by mass of the filler (D).

In the present invention, two or more types of polymer particles (C) having different materials, particle size distributions, and morphologies may be mixed or combined.

[Filler (D)]
The dental composition of the present invention further contains a filler (D). The filler (D) may overlap with the polymer particles (C), but in the present invention, the filler (D) excludes those that overlap with the polymer particles (C). The filler (D) is roughly classified into inorganic fillers and organic-inorganic composite fillers.

Examples of inorganic filler materials include quartz, silica, alumina, silica-titania, silica-titania-barium oxide, silica-zirconia, silica-alumina, lanthanum glass, borosilicate glass, soda glass, barium glass, strontium glass, glass ceramic, aluminosilicate glass, barium boroaluminosilicate glass, strontium boroaluminosilicate glass, fluoroaluminosilicate glass, calcium fluoroaluminosilicate glass, strontium fluoroaluminosilicate glass, barium fluoroaluminosilicate glass, strontium calcium fluoroaluminosilicate glass, ytterbium oxide, and silica-coated ytterbium fluoride. These may also be used alone or in combination of two or more. The shape of the inorganic filler is not particularly limited, and the particle size of the filler can be appropriately selected and used. From the viewpoint of the handleability and mechanical strength of the obtained composition, the average particle size of the inorganic filler is preferably 0.001 to 50 μm, and more preferably 0.001 to 10 μm. In addition, as a preferred embodiment, the filler (D) is a dental composition containing a combination of an ultrafine inorganic filler having an average particle size of 1 nm or more and less than 0.1 μm and an inorganic filler having an average particle size of 0.1 μm or more and 10 μm or less. As another preferred embodiment, the filler (D) is a dental composition containing a combination of an ultrafine inorganic filler having an average particle size of 1 nm or more and less than 0.1 μm and an inorganic filler having an average particle size of 0.1 μm or more and 1 μm or less. In another preferred embodiment, the filler (D) is a dental composition containing a combination of an ultrafine inorganic filler having an average particle size of 1 nm or more and less than 0.1 μm and an inorganic filler having an average particle size of more than 1 μm and 10 μm or less. Furthermore, in another preferred embodiment, the filler (D) is a dental composition containing a combination of an ultrafine particle inorganic filler having an average particle size of 1 nm or more and less than 0.1 μm, an inorganic filler having an average particle size of 0.1 μm or more and 1 μm or less, and an inorganic filler having an average particle size of more than 1 μm and 10 μm or less.

Examples of the shape of the inorganic filler include amorphous fillers and spherical fillers. From the viewpoint of improving the mechanical strength of the composition, it is preferable to use a spherical filler as the inorganic filler. Furthermore, when the spherical filler is used, there is an advantage that when the dental composition of the present invention is used as a self-adhesive dental composite resin, a composite resin with excellent surface smoothness can be obtained. Here, the spherical filler is a filler in which the particles observed within a unit field of view of a filler photographed with an electron microscope are rounded, and the average uniformity obtained by dividing the particle diameter in a direction perpendicular to the maximum diameter by the maximum diameter is 0.6 or more. The average particle diameter of the spherical filler is preferably 0.05 to 5 μm. If the average particle diameter is less than 0.05 μm, the filling rate of the spherical filler in the composition may decrease, and the mechanical strength may decrease. On the other hand, if the average particle diameter exceeds 5 μm, the surface area of the spherical filler may decrease, and a hardened dental composition having high mechanical strength may not be obtained.

In order to adjust the fluidity of the dental composition, the inorganic filler may be surface-treated with a known surface treatment agent such as a silane coupling agent before use, if necessary. Examples of such surface treatment agents include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltrichlorosilane, vinyltri(β-methoxyethoxy)silane, γ-methacryloyloxypropyltrimethoxysilane, 8-methacryloyloxyoctyltrimethoxysilane, 11-methacryloyloxyundecyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-aminopropyltriethoxysilane.

The organic-inorganic composite filler used in the present invention is obtained by adding a monomer compound to the inorganic filler described above in advance, forming a paste, polymerizing it, and pulverizing it. As the organic-inorganic composite filler, for example, TMPT filler (trimethylolpropane methacrylate and silica filler mixed, polymerized, and then pulverized) can be used. The shape of the organic-inorganic composite filler is not particularly limited, and the particle size of the filler can be appropriately selected and used. From the viewpoint of the handleability and mechanical strength of the obtained composition, the average particle size of the organic-inorganic composite filler is preferably 0.001 to 50 μm, and more preferably 0.001 to 10 μm.

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, the laser diffraction scattering method is convenient for measuring the particle size of particles of 0.1 μm or more, while electron microscope observation is convenient for measuring the particle size of ultrafine particles of less than 0.1 μm. 0.1 μm is a value measured by the laser diffraction scattering method.

Specifically, the laser diffraction scattering method can be used, for example, with a laser diffraction particle size distribution measuring device (SALD-2300: manufactured by Shimadzu Corporation) to measure on a volumetric basis using a 0.2% aqueous solution of sodium hexametaphosphate as the dispersion medium.

Electron microscope observation can be performed, for example, by taking a photograph of the particles with an electron microscope (S-4000 model, manufactured by Hitachi, Ltd.) and measuring the particle sizes of the 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.). At this time, the particle size is determined as the arithmetic mean value of the longest and shortest lengths of the particles, and the average primary particle size is calculated from the number of particles and their particle size.

The filler (D) used in the present invention may be a mixture or combination of two or more fillers having different materials, particle size distributions, or morphologies, and may unintentionally contain particles other than the filler as impurities, provided that the effect of the present invention is not impaired.

The content of the filler (D) used in the present invention is not particularly limited, and the filler (D) is preferably 0 to 2000 parts by mass per 100 parts by mass of the total amount of the monomer components in the dental composition. Since the suitable content of the filler (D) varies significantly depending on the embodiment in which it is used, the suitable content of the filler (D) according to each embodiment is shown below along with the explanation of the specific embodiments of the dental composition of the present invention.

[Polymerization accelerator (E)]
In another embodiment, a polymerization accelerator (E) is used together with the water-insoluble photopolymerization initiator (B-2) and/or the chemical polymerization initiator. Examples of the polymerization accelerator (E) used in the present invention include amines, sulfinic acid and its salts, borate compounds, barbituric acid derivatives, triazine compounds, copper compounds, tin compounds, vanadium compounds, halogen compounds, aldehydes, thiol compounds, sulfites, hydrogen sulfites, and thiourea compounds.

Amines used as the polymerization accelerator (E) 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 hardening property and storage stability of the dental composition, and among these, N-methyldiethanolamine and triethanolamine are more preferably used.

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, from the viewpoint of imparting excellent hardening properties to the dental composition, 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.

Specific examples of sulfinic acids and their salts, borate compounds, barbituric acid derivatives, 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.

The above polymerization accelerator (E) may be blended alone or in combination of two or more. The content of the polymerization accelerator (E) used in the present invention is not particularly limited, but from the viewpoint of the hardening property of the obtained dental composition, it is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and even more preferably 0.1 parts by mass or more, and more preferably 30 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, relative to 100 parts by mass of the total amount of the monomer components in the dental composition. If the content of the polymerization accelerator (E) is less than 0.001 parts by mass, the polymerization may not proceed sufficiently, which may lead to a decrease in adhesiveness. The content of the polymerization accelerator (E) is more preferably 0.05 parts by mass or more. On the other hand, if the content of the polymerization accelerator (E) exceeds 30 parts by mass, if the polymerization performance of the polymerization initiator itself is low, sufficient adhesiveness may not be obtained, and further, precipitation from the dental composition may occur. Therefore, the content of the polymerization accelerator (E) is more preferably 20 parts by mass or less.

[Fluoride ion releasing substances]
The dental composition of the present invention may further contain a fluoride ion releasing substance. By incorporating a fluoride ion releasing substance, a dental composition capable of imparting acid resistance to tooth structure can be obtained. Examples of such fluoride ion releasing substances include metal fluorides such as sodium fluoride, potassium fluoride, sodium monofluorophosphate, lithium fluoride, and ytterbium fluoride. The above fluoride ion releasing substances may be incorporated alone or in combination of two or more.

In addition, the dental composition may contain additives such as pH adjusters, polymerization inhibitors, thickeners, colorants, fluorescent agents, fragrances, and crosslinkers (e.g., polyvalent metal ion releasing components, etc.) within the range that does not inhibit the effects of the present invention. The additives may be used alone or in combination of two or more. The dental composition of the present invention may also contain antibacterial substances such as cetylpyridinium chloride, benzalkonium chloride, (meth)acryloyloxydodecylpyridinium bromide, (meth)acryloyloxyhexadecylpyridinium chloride, (meth)acryloyloxydecylammonium chloride, and triclosan. The dental composition of the present invention may contain known dyes and pigments as colorants. Examples of polyvalent metal ion releasing components include metal ion releasing components belonging to Groups 3 and 13 of the periodic table. Examples of metals belonging to Group 3 of the periodic table include yttrium, scandium, and lanthanoids. Examples of metals belonging to Group 13 of the periodic table include aluminum, gallium, and indium. A preferred embodiment of the present invention is a dental composition that does not contain a crosslinking agent such as a polyvalent metal ion releasing component that forms an ionic crosslink with the monomer (B) having an acidic group, in order to appropriately lower the crosslink density in the polymer matrix and not impede the polymerization shrinkage stress reducing effect of the (meth)acrylic compound (A).

In the dental composition of the present invention, the amount of other components other than the monomer (A), polymerization initiator (B), polymer particles (C), filler (D) (excluding polymer particles (C)), polymerization accelerator (E), polymerization inhibitor, and colorant is preferably less than 0.1 part by mass, more preferably less than 0.01 part by mass, and even more preferably less than 0.001 part by mass, per 100 parts by mass of the dental composition.

The dental composition of the present invention can be used in dental treatments such as dental composite resins (particularly preferably self-adhesive dental composite resins), dental cements, pit and fissure sealants, loose tooth fixation materials, and orthodontic bonding materials, and is particularly preferably used as dental composite resins such as self-adhesive dental composite resins, or dental cements. In this case, the dental composition of the present invention may be used in a two-bottle or two-paste form in which the components are separated into two. Specific embodiments of the application of the dental composition are shown below.

<Self-adhesive dental composite resin>
A preferred embodiment of the dental composition of the present invention is a self-adhesive dental composite resin. The self-adhesive dental composite resin made of the dental composition of the present invention contains a monomer (A-1) having an acidic group. When the dental composition of the present invention is used as a self-adhesive dental composite resin, it contains a monomer (A), a polymerization initiator (B), polymer particles (C), a filler (D) and a polymerization accelerator (E), and it is preferable that the monomer (A) contains a monomer (A-1) having an acidic group, a hydrophobic monomer (A-2) having no acidic group, and a hydrophilic monomer (A-3) having no acidic group. In addition, the polymerization initiator (B) is preferably a photopolymerization initiator, and it is more preferable that the polymerization initiator (B) contains a water-soluble photopolymerization initiator (B-1) and a water-insoluble photopolymerization initiator (B-2). When the dental composition of the present invention is used as a self-adhesive dental composite resin, a pretreatment material may be used, but since the dental composition has self-adhesiveness, the pretreatment material is not essential, and the pretreatment material may not be used. A self-adhesive dental composite resin can be produced which does not contain a pretreatment material and is composed only of the dental composition of the present invention.

With regard to the content of each component in the self-adhesive dental composite resin, it is preferable for the dental composition to contain 1 to 50 parts by mass of a monomer (A-1) having an acidic group, 20 to 99 parts by mass of a hydrophobic monomer (A-2) not having an acidic group, and 0 to 50 parts by mass of a hydrophilic monomer (A-3) not having an acidic group, based on a total amount of 100 parts by mass of the monomer components in the dental composition; it is more preferable for the dental composition to contain 1 to 40 parts by mass of a monomer (A-1) having an acidic group, 40 to 99 parts by mass of a hydrophobic monomer (A-2) not having an acidic group, and 0 to 40 parts by mass of a hydrophilic monomer (A-3) not having an acidic group; and it is even more preferable for the dental composition to contain 1 to 30 parts by mass of a monomer (A-1) having an acidic group, 60 to 99 parts by mass of a hydrophobic monomer (A-2) not having an acidic group, and 0 to 30 parts by mass of a hydrophilic monomer (A-3) not having an acidic group. Also, it is preferable to contain 0.001 to 30 parts by mass of polymerization initiator (B), 10 to 500 parts by mass of polymer particles (C), 50 to 2000 parts by mass of filler (D), and 0.001 to 20 parts by mass of polymerization accelerator (E) relative to 100 parts by mass of the total amount of the monomer components, and it is more preferable to contain 0.05 to 10 parts by mass of polymerization initiator (B), 15 to 450 parts by mass of polymer particles (C), 0.05 to 10 parts by mass of polymerization accelerator (E), and 100 to 1500 parts by mass of filler (D). The dental composition used as a self-adhesive dental composite resin does not need to contain the hydrophilic monomer (A-3).

<Dental composite resin>
One of the preferred embodiments of the dental composition of the present invention is a dental composite resin (excluding self-adhesive dental composite resin). The dental composite resin made of the dental composition of the present invention does not contain a monomer (A-1) having an acidic group. When the dental composition of the present invention is used as a dental composite resin, it is preferable that the composition contains a hydrophobic monomer (A-2) having no acidic group, a hydrophilic monomer (A-3) having no acidic group, a polymerization initiator (B), polymer particles (C), a filler (D) and a polymerization accelerator (E). The polymerization initiator (B) is preferably a photopolymerization initiator, and it is more preferable that the polymerization initiator (B) contains a water-soluble photopolymerization initiator (B-1) and a water-insoluble photopolymerization initiator (B-2). When the dental composition of the present invention is used as a dental composite resin, it is essential to use a dental bonding material or a pretreatment material.

With regard to the content of each component in the dental composite resin, it is preferable for the dental composition to contain 50 to 99 parts by mass of hydrophobic monomer (A-2) that does not have an acidic group and 0 to 40 parts by mass of hydrophilic monomer (A-3) that does not have an acidic group, more preferably 60 to 99 parts by mass of hydrophobic monomer (A-2) that does not have an acidic group and 0 to 30 parts by mass of hydrophilic monomer (A-3) that does not have an acidic group, and even more preferably 70 to 99 parts by mass of hydrophobic monomer (A-2) that does not have an acidic group and 0 to 20 parts by mass of hydrophilic monomer (A-3) that does not have an acidic group, based on a total of 100 parts by mass of the monomer components in the dental composition. Further, it is preferable to contain 0.001 to 30 parts by mass of a polymerization initiator (B), 10 to 500 parts by mass of a polymer particle (C), 0.001 to 20 parts by mass of a polymerization accelerator (E), and 50 to 2000 parts by mass of a filler (D) relative to 100 parts by mass of the total amount of the monomer components, and it is more preferable to contain 0.05 to 10 parts by mass of a polymerization initiator (B), 15 to 450 parts by mass of a polymer particle (C), 0.05 to 10 parts by mass of a polymerization accelerator (E), and 100 to 1500 parts by mass of a filler (D). The dental composition used as a dental composite resin does not need to contain the hydrophilic monomer (A-3).

<Dental cement>
Another preferred embodiment of the dental composition of the present invention is a dental cement. Suitable dental cements include resin cement, glass ionomer cement, and resin-reinforced glass ionomer cement. A self-etching primer may be used as a pretreatment material for the dental cement. When the dental composition of the present invention is used as a dental cement, it contains a monomer (A), a polymerization initiator (B), polymer particles (C), a filler (D), and a polymerization promoter (E), and it is preferable that the monomer (A) contains a monomer (A-1) having an acidic group, a hydrophobic monomer (A-2) having no acidic group, and a hydrophilic monomer (A-3) having no acidic group. It is preferable that the polymerization initiator (B) contains a chemical polymerization initiator, and it is more preferable that the polymerization initiator contains a chemical polymerization initiator and a photopolymerization initiator. It is preferable that the photopolymerization initiator contains a water-soluble photopolymerization initiator (B-1) and a water-insoluble photopolymerization initiator (B-2).

With regard to the content of each component in the dental cement, it is preferable that the dental composition contains 0 to 50 parts by mass of a monomer (A-1) having an acidic group, 50 to 99 parts by mass of a hydrophobic monomer (A-2) not having an acidic group, and 0 to 50 parts by mass of a hydrophilic monomer (A-3) not having an acidic group, based on a total of 100 parts by mass of the monomer components in the dental composition; it is more preferable that the dental composition contains 0 to 40 parts by mass of a monomer (A-1) having an acidic group, 60 to 99 parts by mass of a hydrophobic monomer (A-2) not having an acidic group, and 0 to 40 parts by mass of a hydrophilic monomer (A-3) not having an acidic group; and it is even more preferable that the dental composition contains 0 to 30 parts by mass of a monomer (A-1) having an acidic group, 70 to 99 parts by mass of a hydrophobic monomer (A-2) not having an acidic group, and 0 to 30 parts by mass of a hydrophilic monomer (A-3) not having an acidic group. Further, it is preferable to contain 0.001 to 30 parts by mass of polymerization initiator (B), 10 to 500 parts by mass of polymer particles (C), 0.001 to 20 parts by mass of polymerization accelerator (E), and 50 to 2000 parts by mass of filler (D) relative to 100 parts by mass of the total amount of the monomer components, and it is more preferable to contain 0.05 to 10 parts by mass of polymerization initiator (B), 15 to 450 parts by mass of polymer particles (C), 0.05 to 10 parts by mass of polymerization accelerator (E), and 100 to 1500 parts by mass of filler (D). It is not necessary to contain hydrophilic monomer (A-3), and in the case of a type using a pretreatment material, it is not necessary to contain monomer (A-1) having an acidic group.

In any of the preferred embodiments of the above-mentioned self-adhesive dental composite resin, dental composite resin, and dental cement, the content of each component can be changed as appropriate based on the explanation in the above specification, and any component can be added, deleted, or otherwise modified.

The present invention includes embodiments that combine the above configurations in various ways within the scope of the technical concept of the present invention, as long as the effects of the present invention are achieved.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. Furthermore, not all of the combinations of features described in the examples are necessarily essential to the solution of the present invention. The components used in the following examples and comparative examples, along with their abbreviations, structures, and test methods, are as follows:

[Monomer (A)]
MDP: 10-methacryloyloxydecyl dihydrogen phosphate D-2.6E: 2,2-bis(4-methacryloyloxypolyethoxyphenyl)propane (average number of moles of ethoxy groups added: 2.6)
DD: 1,10-decanediol dimethacrylate MAEA: N-methacryloyloxyethyl acrylamide

・非水溶性光重合開始剤（Ｂ－２）
ＣＱ：ｄｌ－カンファーキノン [Polymerization initiator (B)]
Water-soluble photopolymerization initiator (B-1)
Li-TPO: Lithium phenyl(2,4,6-trimethylbenzoyl)phosphinate (compound represented by the following formula (3))

Non-water-soluble photopolymerization initiator (B-2)
CQ: dl-camphorquinone

[Polymer particles (C)]
SBX-4: Spherical cross-linked polystyrene particles (manufactured by Sekisui Chemical Co., Ltd., Techpolymer (registered trademark) SBX-4, average particle size: 4 μm, refractive index: 1.59)
SBX-6: Spherical cross-linked polystyrene particles (manufactured by Sekisui Chemical Co., Ltd., Techpolymer (registered trademark) SBX-6, average particle size: 6 μm, refractive index: 1.59)
SBX-8: Spherical cross-linked polystyrene particles (manufactured by Sekisui Chemical Co., Ltd., Techpolymer (registered trademark) SBX-8, average particle size: 8 μm, refractive index: 1.59)
MSX-6: Spherical cross-linked methyl methacrylate-styrene copolymer particles (manufactured by Sekisui Chemical Co., Ltd., Techpolymer (registered trademark) MSX-6, average particle size: 6 μm, refractive index: 1.57)

[Filler (D)]
Inorganic filler 1: fine particle silica "Aerosil (registered trademark) R 972" manufactured by Nippon Aerosil Co., Ltd., average particle size: 16 nm, refractive index: 1.46
Inorganic filler 2: silane-treated silica powder, refractive index: 1.55
Silica powder (manufactured by Nichitsu Corporation, product name: Hi-Silica) was pulverized in a ball mill to obtain pulverized silica powder. The average particle size of the obtained pulverized silica powder was measured on a volume basis using a laser diffraction particle size distribution measuring device (manufactured by Shimadzu Corporation, model "SALD-2300") using a 0.2% sodium hexametaphosphate aqueous solution as a dispersion medium, and was found to be 2.2 μm. 100 parts by mass of this pulverized silica powder was surface-treated with 4 parts by mass of γ-methacryloyloxypropyltrimethoxysilane by a conventional method to obtain silane-treated silica powder.
Inorganic filler 3: silane-treated barium glass powder, refractive index: 1.55
Barium glass (manufactured by Estec Co., Ltd., product code "E-3000") was pulverized in a ball mill to obtain barium glass powder. The average particle size of the obtained barium glass powder was measured by volume using a laser diffraction particle size distribution measuring device (manufactured by Shimadzu Corporation, model "SALD-2300") using a 0.2% sodium hexametaphosphate aqueous solution as a dispersion medium, and was found to be 2.4 μm. 100 parts by mass of this barium glass powder was surface-treated with 3 parts by mass of γ-methacryloyloxypropyltrimethoxysilane by a conventional method to obtain silane-treated barium glass powder.
Inorganic filler 4: silane-treated barium glass powder, refractive index: 1.53
100 g of 8235 UF0.7 grade (barium glass manufactured by SCHOTT, average particle size: 0.7 μm), 6 g of γ-methacryloyloxypropyltrimethoxysilane, and 200 mL of 0.3 mass% acetic acid aqueous solution were placed in a three-neck flask and stirred at room temperature for 2 hours. After removing water by freeze-drying, the mixture was heated at 80° C. for 5 hours to obtain inorganic filler 4.
Inorganic filler 5: silane-treated barium glass powder, refractive index: 1.53
100 g of GM27884 NF180 grade (barium glass manufactured by SCHOTT, average particle size: 0.18 μm), 13 g of γ-methacryloyloxypropyltrimethoxysilane, and 200 mL of 0.3 mass% acetic acid aqueous solution were placed in a three-neck flask and stirred at room temperature for 2 hours. After removing water by freeze-drying, the mixture was heated at 80° C. for 5 hours to obtain inorganic filler 5.

[Polymerization accelerator (E)]
DAB: ethyl 4-(N,N-dimethylamino)benzoate

〔others〕
BHT: 2,6-di-t-butyl-4-methylphenol (stabilizer (polymerization inhibitor))

[Example 1 and Comparative Example 1 Application of dental composition to dental composite resin and self-adhesive dental composite resin]
<Examples 1 to 12 and Comparative Examples 1 and 2>
Using the above-mentioned components, the components shown in Table 1 were mixed and kneaded at room temperature to prepare dental composite resin pastes (compositions) of Examples 1 to 10, self-adhesive dental composite resins of Examples 11 and 12, and dental composite resin pastes of Comparative Examples 1 and 2. Next, using these pastes, the cure depth, polymerization shrinkage stress, bending strength, and light diffusion degree D of the paste before curing were measured according to the methods described below. Table 1 shows the compounding ratios (parts by mass) and test results of the dental composite resins of each Example and Comparative Example.

[Cure depth]
The dental composite resin paste of each Example and Comparative Example was filled into a stainless steel mold (thickness 10 mm, diameter 2 mm). The top and bottom surfaces were pressed together with a film and a slide glass in that order, and the glass plate was removed from one side of the film. The pressed surface of the film was irradiated with light for 10 seconds using a dental LED light irradiator (Morita Corporation, "Pencure 2000") to cure. After removing the cured product from the mold, the uncured part was wiped off, and the curing depth from the light irradiated surface was measured using a micrometer (Mitutoyo Corporation), and the half of the actual measured value was taken as the curing depth (N=5), and the average value was calculated.

[Measurement of Polymerization Shrinkage Stress]
A stainless steel washer (inner diameter 5.3 mm x thickness 0.8 mm) coated with a release agent was placed on a 5.0 mm thick glass plate sandblasted with 50 μm alumina powder, and the dental composite resin paste of each Example and Comparative Example was filled into the washer. Next, excess dental composite resin paste was removed, and the dental composite resin paste was sandwiched between a stainless steel jig (φ5 mm) separately sandblasted and the glass plate.

The glass plate side of the paste was irradiated with light for 10 seconds using a dental LED light irradiator (manufactured by Morita Corporation, product name "Pencure 2000") to harden the dental composite resin, and the polymerization shrinkage stress at this time was measured (N=3) using a universal testing machine (Autograph AG-I 100kN, manufactured by Shimadzu Corporation) and the average value was calculated.

[Evaluation of bending properties]
The strength was evaluated by a bending test in accordance with ISO4049:2009. Specifically, the following procedure was followed. A dental composite resin paste was filled into a SUS mold (length 2 mm x width 25 mm x thickness 2 mm), and the top and bottom (2 mm x 25 mm surfaces) of the paste (dental composition) were pressed with a glass slide. Next, the dental composition was cured by irradiating the front and back of the paste through the glass slide for 10 seconds at five points on each side using a dental LED light irradiator (Morita Corporation, "Pencure 2000"). The obtained cured product was subjected to a bending test at a crosshead speed of 1 mm/min using a universal testing machine (Autograph AG-I 100 kN, Shimadzu Corporation), and the bending strength was measured (N=5), and the average value was calculated.

[Measurement of light diffusion degree D before curing]
The dental composite resins of each Example and Comparative Example were filled into a Teflon (registered trademark) mold (diameter 30 mm x thickness 0.25 mm). The top and bottom surfaces were pressed against slide glass, and the luminous intensity distribution of the transmitted light was measured (N=3) using a three-dimensional variable-angle photometer ("GP-200" manufactured by Murakami Color Research Laboratory Co., Ltd., halogen light source, color temperature approximately 6774K). The light diffusion degree D was calculated according to the following formula [I], and the average value of the obtained light diffusion degrees D was calculated.
D = ( _I20 /cos20° + _I70 /cos70°)/( _2I0 ) [I]
(In the formula, I represents the luminous intensity of light transmitted through the sample, and I ₀ , I ₂₀ and I ₇₀ represent the luminous intensity (light intensity) at 0 degrees, 20 degrees and 70 degrees, respectively, relative to the direction perpendicular to the sample plate (the direction of incidence of light).)

[Measurement of refractive index of entire monomer mixture before curing]
The refractive index of the entire monomer mixture before curing was measured directly using an Abbe refractometer (manufactured by Atago Co., Ltd., product name: 1T) at 23° C. The entire monomer mixture before curing was set in the Abbe refractometer, and the refractive index was measured.

As shown in Table 1, the dental composite resins according to the present invention (Examples 1 to 10) and the self-adhesive dental composite resins (Examples 11 to 12) had a bending strength of 3 mm or more and a low polymerization shrinkage stress of 11.2 MPa or less, and also exhibited a bending strength of 95 MPa or more and a light diffusion index D of 0.20 or more. This suggests that the polymerization shrinkage stress is alleviated by containing polymer particles (C) and having a specific light diffusion index D. In contrast, the dental composite resins (Comparative Examples 1 to 2) that did not contain polymer particles (C) or had a light diffusion index D of less than 0.10 before curing each had a polymerization shrinkage stress of 12 MPa or more, and it was confirmed that the reduction in polymerization shrinkage stress was insufficient. In Comparative Example 2, although the refractive index difference between the polymer particles (C) and the total monomer mixture before curing was the same as in Example 10, the light diffusion index D before curing was less than 0.10 due to the different content of polymer particles (C), and the reduction in polymerization shrinkage stress was insufficient.

The dental composition of the present invention is suitable for use in the field of dental care as a dental composite resin, a self-adhesive dental composite resin, and a dental cement.

a Light incident direction 1 Sample plate L ₁ Incident light L ₀ Transmitted light I ₀ Transmitted light at an angle of 0 degrees to the incident direction of light I ₂₀ Transmitted light at an angle of 20 degrees to the incident direction of light I ₇₀ Transmitted light at an angle of 70 degrees to the incident direction of light

Claims (18)

A dental composition comprising a monomer (A), a polymerization initiator (B), polymer particles (C), and a filler (D) (excluding the polymer particles (C)), wherein the dental composition before curing has a light diffusion index D represented by the following formula [I] of 0.10 or more.
D = ( _I20 /cos20° + _I70 /cos70°)/( _2I0 ) [I]
(In the formula, I represents the luminous intensity of light transmitted through the sample, and I ₀ , I ₂₀ and I ₇₀ represent the luminous intensity (light intensity) at 0 degrees, 20 degrees and 70 degrees, respectively, relative to the direction perpendicular to the sample plate (the direction of incidence of light).) The dental composition described in claim 1, wherein the average particle diameter of the polymer particles (C) is 0.5 μm to 50 μm. A dental composition according to claim 1 or 2, wherein the filler (D) is an inorganic filler. A dental composition according to any one of claims 1 to 3, wherein the polymer particles (C) are crosslinked polymer particles. A dental composition described in any one of claims 1 to 4, wherein the refractive index of the polymer particles (C) is 1.550 or more. A dental composition described in any one of claims 1 to 5, wherein the content of the polymer particles (C) is 0.1 parts by mass to 20 parts by mass per 100 parts by mass of the dental composition. A dental composition described in any one of claims 1 to 6, wherein the content of the polymer particles (C) is 0.1 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the total amount of the monomer components. A dental composition described in any one of claims 1 to 7, wherein the polymer particles (C) are spherical. A dental composition described in any one of claims 1 to 8, wherein the refractive index difference between the polymer particles (C) and the total monomer mixture before hardening is 0.020 or more. A dental composition according to any one of claims 1 to 9, wherein the polymer particles (C) consist of (meth)acrylic polymer particles or styrene polymer particles. A dental composition described in any one of claims 1 to 10, wherein the monomer (A) includes a monomer (A-1) having an acidic group. A dental composition described in any one of claims 1 to 11, wherein the monomer (A) includes a hydrophobic monomer (A-2) that does not have an acidic group. A dental composition described in any one of claims 1 to 12, wherein the polymerization initiator (B) includes a non-water-soluble photopolymerization initiator (B-2). A dental composition described in any one of claims 1 to 13, wherein the filler (D) comprises an ultrafine inorganic filler having an average particle diameter of 1 nm or more and less than 0.1 μm. A dental composition described in any one of claims 1 to 13, wherein the filler (D) comprises an inorganic filler having an average particle diameter of more than 1 μm and not more than 10 μm. A dental composite resin comprising a dental composition according to any one of claims 1 to 15. A self-adhesive dental composite resin comprising a dental composition according to any one of claims 1 to 15. A dental cement comprising the dental composition according to any one of claims 1 to 15.

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