JP7496984B2 - Dental adhesive composition - Google Patents

Description

The present invention relates to a novel dental composition. More specifically, the present invention relates to a dental adhesive composition that contains a polymerizable monomer component including an acidic group-containing polymerizable monomer, and that can obtain high adhesion due to a demineralizing effect even when a small amount of solvent is added.
Regarding.

In dental treatment, when treating teeth damaged by caries or accidents, it is necessary to strongly bond such teeth to dental restorative materials such as composite resins, and various dental adhesives have been proposed for this purpose. Such dental adhesives usually contain a polymerizable monomer component containing a polymerizable monomer having an acidic group (hereinafter also referred to as "acidic monomer") and a polymerization initiator that is mixed as necessary, and the polymerizable monomer component hardens to form an adhesive layer that is firmly bonded to an adherend such as tooth tissue. In addition, dental adhesives often contain a solvent consisting of water and/or a water-soluble organic solvent to promote demineralization of the tooth tissue by the acidic monomer and penetration of the adhesive into the tooth tissue. The viscosity of a dental adhesive containing a solvent decreases with an increase in the amount of solvent added, so there is an advantage in that the viscosity can be controlled by the amount of solvent added. However, when a thick adhesive layer is required, the amount of solvent added must be reduced, and there is a problem that the demineralization action on the tooth tissue is weak and sufficient adhesive strength cannot be obtained when the amount of water added is particularly small.

As a method for solving this problem, a method of making a specific composition that can obtain demineralization power without using a solvent is known. For example, Patent Document 1 describes a radical polymerizable dental material that contains at least one radical polymerizable oligomer or polymer (hereinafter also referred to as "acidic oligomer, etc.") having a strongly acidic group, and the radical polymerizable oligomer or polymer has a number average molecular weight of 1000 g/mol to 200,000 g/mol. Patent Document 1 also describes that the inclusion of the oligomer or polymer having the strongly acidic group promotes demineralization of the tooth tissue, and the radical polymerizable dental material not only obtains high adhesion even without a solvent, but also prevents the thickness of the adhesive layer from being excessively reduced even when a solvent is added, because the oligomer or polymer component suppresses the viscosity reduction caused by the addition of a solvent. Patent Document 2 describes a non-solvent-based dental self-etching composition that contains (A) a polymerizable monomer that contains at least a sulfonic acid group-containing polymerizable monomer (a1) as a part thereof, and (B) a photopolymerization initiator having a carbonyl group, and that is characterized in that the total content of primary alcohol compounds and 1,2-diol compounds is less than 10 parts by mass per 100 parts by mass of the total polymerizable monomers. Patent Document 2 also describes that this composition contains a highly acidic sulfonic acid group-containing polymerizable monomer, and thus has excellent demineralizing power even without a solvent, and exhibits high adhesive strength to tooth structure.

Patent Publication 2017-25058 Patent Publication 2016-69281

The adhesive dental materials made of the polymerizable compositions disclosed in Patent Documents 1 and 2 above all have a demineralizing effect and can provide high adhesion even in systems with low solvent content or non-solvent systems, but they are not necessarily satisfactory in the following respects.

In other words, the polymerizable dental material disclosed in Patent Document 1 not only requires that the acidic monomer be polymerized beforehand to obtain an acidic oligomer having a specific molecular weight, but also that the components with demineralizing properties are less likely to penetrate into the tooth structure than when only the acidic monomer is used, and in order to ensure sufficient penetration into the tooth structure, it is necessary to promote penetration into the tooth structure by rubbing for an additional 20 seconds after application of the adhesive during the bonding operation.

On the other hand, in the non-solvent-based dental self-etching composition disclosed in Patent Document 2, it is necessary to mix about 3 parts by mass of the sulfonic acid group-containing polymerizable monomer (a1) per 100 parts by mass of the polymerizable monomer, and there is a risk that the strong acidity of the monomer may cause pain to the patient.

In view of this situation, the first object of the present invention is to provide a dental adhesive composition that exhibits sufficient dentin demineralization and permeability even in a composition containing a small amount of solvent, and exhibits dentin adhesion even when a thick adhesive layer is required, by a method other than the techniques disclosed in Patent Documents 1 and 2. Secondly, the second object of the present invention is to provide a dental adhesive composition that exhibits sufficient dentin demineralization and permeability even in a composition containing a small amount of solvent, and exhibits dentin adhesion even when a thick adhesive layer is required, without using acidic oligomers or sulfonic acid group-containing polymerizable monomers.

The inventors of the present invention conducted extensive research to solve the above technical problems. As a result, they discovered that the use of an acetamide-based polymerizable monomer with a specific structure can enhance the dentin demineralization and penetration properties of the adhesive, thereby improving adhesive strength, and thus completed the present invention.

That is, a first aspect of the present invention is a dental adhesive composition comprising a polymerizable monomer component consisting of an acidic group-containing polymerizable monomer and an acidic group-free polymerizable monomer, wherein 2 parts by mass or more and 40 parts by mass or less of 100 parts by mass of the polymerizable monomer component is the acidic group-containing polymerizable monomer, and the remainder is the acidic group-free polymerizable monomer, and the acidic group-free polymerizable monomer comprises 5 parts by mass or more and 60 parts by mass or less of an acetamide-based polymerizable monomer consisting of at least one compound selected from the group consisting of compounds represented by the following general formulae (1) to (6) and compounds represented by the following general formulae (7) to (10) {excluding compounds in which n is 1 in the following general formulae (1) and (4)} relative to 100 parts by mass of the polymerizable monomer component,
The dental adhesive composition is characterized by the above.

The general formulas (1) to (10) are "skeletal structural formulas" that are structural formulas in which the carbon chains consisting of carbon atoms are simplified to show only the functional groups, and in these general formulas, n means a natural number from 1 to 30. However, as described above, compounds in which n is 1 in the general formulas (1) to (4), specifically, N-acryloyloxyethylacetamide, N-methacryloyloxyethylacetamide, N-methyl-N-acryloyloxyethylacetamide, and N-methyl-N-methacryloyloxyethylacetamide, are excluded from the compounds that become the acetamide-based polymerizable monomers.

It is also preferable that the dental adhesive composition of the present invention does not contain a solvent or contains less than 30 parts by mass of a solvent per 100 parts by mass of the polymerizable monomer component.

In addition, in the dental adhesive composition of the present invention, the amount of the sulfo group-containing polymerizable monomer that may be contained in the acidic group-containing polymerizable monomer is preferably less than 0.1 parts by mass relative to 100 parts by mass of the polymerizable monomer component, and further, it is preferable that 98% by mass or more of the acidic group-containing polymerizable monomer is composed of a polymerizable monomer having, as an acidic group, at least one group selected from the group consisting of a carboxyl group (-COOH), a phosphinico group {=P(=O)OH}, and a phosphono group {-P(=O)(OH) ₂ }.

The dental adhesive composition of the present invention exhibits sufficient dentin demineralization and penetration even with a composition containing a small amount of solvent, without using acidic oligomers or sulfonic acid group-containing polymerizable monomers, and can obtain dentin adhesion even when a thick adhesive layer is required.

The dental adhesive composition of the present invention is a dental adhesive composition containing a polymerizable monomer component consisting of an acidic group-containing polymerizable monomer (acidic monomer) and an acidic group-free polymerizable monomer (non-acidic monomer), characterized in that 2 to 40 parts by mass of 100 parts by mass of the polymerizable monomer component is the acidic group-containing polymerizable monomer, and the remainder is the acidic group-free polymerizable monomer, and the acidic group-containing polymerizable monomer contains 5 to 60 parts by mass or less of an acetamide-based polymerizable monomer represented by general formula (1) (hereinafter, also referred to as "specific acetamide-based monomer") relative to 100 parts by mass of the polymerizable monomer component.
The dental adhesive composition of the present invention will be described in detail below, focusing on each component contained in the dental adhesive composition of the present invention. In this specification, unless otherwise specified, the expression "x to y" using numerical values x and y means "x or more and y or less". In such an expression, when a unit is added only to the numerical value y, the unit is also applied to the numerical value x. In addition, in this specification, the term "(meth)acrylic" means both "acrylic" and "methacrylic". Similarly, the term "(meth)acrylate" means both "acrylate" and "methacrylate", and the term "(meth)acryloyl" means both "acryloyl" and "methacryloyl".

1. Polymerizable Monomer Component The dental adhesive composition of the present invention contains a polymerizable monomer component (hereinafter also referred to as "monomer component") as an essential component. The monomer component is a component that constitutes an adhesive layer that is bonded to an adherend by polymerization and hardening, and is made of a polymerizable monomer, that is, a compound having at least one polymerizable unsaturated group in the molecule. Examples of the polymerizable unsaturated group include (meth)acryloyl groups such as (meth)acryloxy groups, (meth)acryloylamino groups, and (meth)acryloylthio groups, as well as radical polymerizable groups such as vinyl groups, allyl groups, and styryl groups. From the viewpoint of polymerizability and safety to living organisms, it is particularly preferable to use a (meth)acrylic acid ester-based radical polymerizable monomer having a (meth)acryloxy group. The monomer component may be made of only one type of monomer or a mixture of multiple types of monomers.

The monomer component in the dental adhesive composition of the present invention must contain 2 to 40 parts by mass of an acidic group-containing polymerizable monomer (acidic monomer) relative to 100 parts by mass of the monomer component in order to provide dentin demineralization. If the content of the acidic monomer relative to 100 parts by mass of the monomer component is less than 2 parts by mass, sufficient dentin demineralization cannot be obtained, and if the content exceeds 40 parts by mass, the strength of the adhesive layer decreases, resulting in a decrease in dentin adhesive strength, and the hydrolysis of the polymerizable monomer is promoted, resulting in poor storage stability. From the viewpoint of dentin adhesiveness and storage stability, the above-mentioned amount of the acidic monomer is preferably 5 to 30 parts by mass. Note that the monomer components other than the acidic monomer are composed of acidic group-free polymerizable monomers (hereinafter also referred to as "non-acidic monomers"), and the amount of the non-acidic monomer relative to 100 parts by mass of the monomer component is necessarily the amount remaining after subtracting the amount of the acidic monomer (parts by mass) from 100 parts by mass.
The acidic and non-acidic monomers are described in detail below.

<Acidic Group-Containing Polymerizable Monomer (Acidic Monomer)>
The acidic monomer is a polymerizable monomer having an acidic group such as a carboxyl group (-COOH), a sulfo group (-SO ₃ H), a phosphinico group {=P(=O)OH}, a phosphono group {-P(=O)(OH) ₂ }, an acid anhydride skeleton {-C(=O)-O-C(=O)-}, or a haloformyl group {-C(=O)X, where X represents a halogen atom} in the molecule, and has a function of enhancing adhesion to dentin, base metal materials, and metal oxide materials. In order to reduce the risk of postoperative pain, the acidic monomer is preferably substantially free of a sulfo group-containing polymerizable monomer, specifically, the content of the sulfo group-containing polymerizable monomer relative to 100 parts by mass of the polymerizable monomer component is preferably less than 0.1 parts by mass, particularly 0.05 parts by mass or less. In addition, because the acidic monomer has high stability to water when it contains water and can slowly dissolve the smear layer on the tooth surface and demineralize the teeth, it is preferable that 98% by mass or more, particularly 99% by mass or more of the acidic monomer is a polymerizable monomer having at least one group selected from the group consisting of a carboxyl group (-COOH), an acid anhydride group {-C(=O)-O-C(=O)-}, a phosphinico group {=P(=O)OH} and a phosphono group {-P(=O)(OH) ₂ } as an acidic group. From the viewpoint of effectiveness, it is particularly preferable that the acidic monomer is a (meth)acrylate of a dihydrogen phosphate monoester type {having a group: -O-P(=O)(OH) ₂ }. }, a dihydrogen phosphate diester type {having a group: (-O-) ₂ P(=O)OH. } or a carboxylic acid type (having a group: -COOH).

Specific examples of acidic monomers that can be suitably used include dihydrogen phosphate monoesters and dihydrogen phosphate diesters, such as 2-(meth)acryloxyethyl dihydrogen phosphate, bis[2-(meth)acryloxyethyl]hydrogen phosphate, 2-(meth)acryloxyethylphenyl hydrogen phosphate, 6-(meth)acryloxyhexyl dihydrogen phosphate, 6-(meth)acryloxyhexylphenyl hydrogen phosphate, 10-(meth)acryloxydecyl dihydrogen phosphate, 1,3-di(meth)acryloylpropane-2-dihydrogen Examples of carboxylic acids include acrylic acid, methacrylic acid, 4-(meth)acryloxyethyl trimellitic acid, 11-(meth)acryloxy 1,1-undecanedicarboxylic acid, 1,4-di(meth)acryloxypyromellitic acid, 2-(meth)acryloxyethyl maleic acid, 2-(meth)acryloxyethyl phthalic acid, and 2-(meth)acryloxyethyl hexahydrophthalic acid.

<Polymerizable monomer not containing an acidic group (non-acidic monomer)>
The non-acidic monomer not only serves as a component of the adhesive layer, but also has the function of increasing the adhesion to dental materials containing radically polymerizable monomers such as composite resins by the polyfunctional polymerizable non-acidic monomer, and introducing a crosslinking structure into the adhesive layer to increase the strength, and thus further increasing the durable adhesion. The non-acidic monomer is not particularly limited as long as it is a monomer other than acidic monomers, but in the dental adhesive composition of the present invention, in order to obtain the above-mentioned effect, it is necessary to contain 5 to 60 parts by mass, preferably 15 to 40 parts by mass, of an acetamide-based polymerizable monomer (specific acetamide-based monomer) described in detail below, relative to 100 mass of the polymerizable monomer component. Note that, when the specific acetamide-based monomer does not account for the entire amount of the non-acidic monomer, non-acidic monomers other than the specific acetamide-based monomer (also referred to as "other non-acidic monomers") account for the remaining portion other than the acidic monomer and the specific acetamide-based monomer in the monomer component.

<Acetamide-based polymerizable monomer (specific acetamide-based monomer)>
The acetamide-based polymerizable monomer (specific acetamide-based monomer) used as the non-acidic monomer in the dental adhesive composition of the present invention will be described below .

That is, the specific acetamide monomer is composed of at least one compound selected from the group consisting of compounds represented by the general formulas (1) to (6) (mono(meth)acrylates) and compounds represented by the general formulas (7) to (10) (di(meth)methacrylates), except for compounds represented by the general formulas (1) to (4) where n is 1. The acetamide polymerizable monomer may be composed of a single compound or a mixture of multiple compounds . For synthesis reasons, the specific acetamide monomer is often obtained as such a mixture, and such a mixture can be expressed by using a weighted average of n in the compounds contained in the mixture (for example, n=1.5 in the case of a mixture of 50 mol% of a compound where n=1 and 50 mol% of a compound where n=2).

Specific acetamide monomers have high hydrophilicity due to the acetamide structure, which allows them to penetrate into tooth tissue and improve the adhesive strength of the adhesive composition to the tooth tissue. In addition, although the detailed mechanism is unclear, it is speculated that the acetamide structure has a good affinity with inorganic ions, and therefore a high affinity with calcium ions, which promotes the dissolution of the layer of shavings (smear layer) remaining on the tooth surface after caries cutting and plasticization due to demineralization of the tooth surface.

The specific acetamide monomer has an acryloyloxy group or a methacryloyloxy group as a radical polymerizable group.

General formulas (1) to (10) showing the structures of compounds that become the specific acetamide monomers used in the dental adhesive composition of the present invention are shown below. Note that , although n in the following general formulas (1) to (10) means 1 to 30, from the viewpoint of having appropriate hydrophilicity and molecular size, n is preferably 1 to 20. However, as described above, compounds in which n is 1 in the general formulas (1) to (4) are excluded from the compounds that become the acetamide polymerizable monomers.

<Other non-acidic monomers>
As the other non-acidic monomer, any non-acidic monomer used in conventional dental adhesive compositions can be used without any particular limitation, so long as it is a non-acidic monomer other than the specific acetamide monomer.

Examples of other non-acidic monomers that can be suitably used include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, glycidyl (meth)acrylate, 2-cyanomethyl (meth)acrylate, benzyl methacrylate, polyethylene glycol mono(meth)acrylate, allyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, glyceryl mono(meth)acrylate, (meth)acrylamide, 6-(meth)acrylamidohexanoic acid, N-butyl (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide. monofunctional polymerizable monomers such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, 2,2'-bis[4-(meth)acryloyloxyethoxyphenyl]propane, 2,2'-bis[4-(meth)acryloxyethoxyethoxyphenyl]propane, 2,2'-bis[4-(meth)acryloxyethoxyethoxyphenyl]propane, 2,2'-bis[4-(meth)acryloxyethoxyethoxyphenyl]propane, 2,2'-bis{4-[2-hydroxy-3-(meth)acryloxypropoxy]phenyl}propane, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-bis(methacrylethyloxycarbonylamino)-2,2,4-trimethylhexane, 1,6-bis(methacrylethyloxycarbonylamino)-2,4,4-trimethylhexane, urethane (meth)acrylate, epoxy (meth)acryl Examples of suitable non-acidic monomers include polyfunctional polymerizable monomers such as acrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, glycerol di(meth)acrylate, N,N'-(1,2-dihydroxyethylene)bis(meth)acrylamide, and N,N'-ethylenebis(meth)acrylamide; fumarate ester compounds such as monomethyl fumarate, diethyl fumarate, and diphenyl fumarate; styrene and α-methylstyrene derivatives such as styrene, divinylbenzene, α-methylstyrene, and α-methylstyrene dimer; and allyl compounds such as diallyl phthalate, diallyl terephthalate, diallyl carbonate, and allyl diglycol carbonate. These other non-acidic monomers may be used alone or in combination.

2. Components other than the monomer component As described above, the dental adhesive composition of the present invention exerts dentin demineralization and penetration even when it does not contain any solvent or when the amount of the solvent is small, and exerts the effect of developing dentin adhesion even when a thick adhesive layer is required, but it is of course possible to incorporate a normal amount of solvent. In addition, as in the case of conventional dental adhesive compositions, a polymerization initiator component can be incorporated as necessary. Furthermore, as long as it does not inhibit the effects of the present invention, components such as run coupling agents, polymerization inhibitors, pigments, polymers, fillers, fungicides, and antibacterial agents can be appropriately incorporated. Below, the solvent and polymerization initiator that are often incorporated will be explained.

<Solvent>
When a solvent is blended into the dental adhesive composition of the present invention, the solvent may be water, alcohols, ketones, ethers, aromatic solvents, hydrocarbon solvents, chlorine-based solvents, fluorine-based solvents, etc., but it is preferable to use water and/or a water-soluble organic solvent from the viewpoint of low toxicity and adhesiveness, etc., and it is particularly preferable to use water and a water-soluble organic solvent because it provides higher adhesiveness. Examples of water-soluble organic solvents that can be suitably used include acetone, ethanol, isopropyl alcohol, etc.

The amount of these solvents is not particularly limited, but from the viewpoint of ease of solvent removal by air blowing, it is preferable that the amount is 30 parts by mass or less per 100 parts by mass of the monomer component, and because the effect of the present invention is more pronounced, it is more preferable that the amount is 20 parts by mass or less, and in particular 10 parts by mass or less.

<Polymerization initiator>
As the polymerization initiator, any polymerization initiator that can be used in a conventional dental adhesive composition, such as a photopolymerization initiator, a chemical polymerization initiator, a thermal polymerization initiator, etc., can be used without any particular limitation. In addition, as in the conventional dental adhesive composition, when the polymerization initiator is composed of a plurality of components, it may contain all or a part of the components constituting the polymerization initiator.

From the viewpoint of ease of operation, it is preferable to use a photopolymerization initiator and/or a chemical polymerization initiator. As the photopolymerization initiator, a photosensitizer that generates radicals by irradiation with light, or a combination of the photosensitizer and a photopolymerization accelerator is preferably used. Here, as the photosensitizer, α-diketones such as camphorquinone, acylphosphine oxides such as phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, benzoin compounds, benzophenone compounds, thioxanthone compounds, coumarins, halomethyl group-substituted s-triazine derivatives, etc. can be used, and as the photopolymerization accelerator, a tertiary aromatic amine compound in which a nitrogen atom is directly substituted on an aromatic group such as p-dimethylaminobenzoic acid ethyl ester can be used.

As the chemical polymerization initiator, a chemical polymerization initiator that combines an oxidizing agent, a reducing agent, and, if necessary, a transition metal compound is preferably used. Specific examples of chemical polymerization initiators include a combination of an organic peroxide and an amine; a combination of an organic peroxide, an amine, and a sulfinic acid salt; a combination of an acidic compound and an aryl borate compound; a combination of a fourth-period transition metal compound and an organic peroxide; a combination of an organic peroxide and a thiourea derivative; barbituric acid; and alkylborane.

When a polymerization initiator is added, the amount of the polymerization initiator components added is preferably 0.0005 parts by mass to 10 parts by mass, and more preferably 0.001 parts by mass to 5 parts by mass, per 100 parts by mass of the monomer components.

3. Suitable uses of the dental adhesive composition of the present invention The dental adhesive composition of the present invention can be suitably used as a "light-curing or chemically curing bonding material" used for bonding a composite resin, which is a material for repairing small cavities, to tooth structure, or as a "dental cement" or "pretreatment agent (primer)" used for bonding a ceramic or metal crown material for repairing large defects to tooth structure.

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

1. First, the substances and their abbreviations used in the dental adhesive compositions of each Example and Comparative Example will be explained below.
<(A) Acidic Group-Containing Polymerizable Monomer (Acidic Monomer)>
MDP: 10-methacryloxydecyl dihydrogen phosphate 4-META: 4-methacryloyloxyethyl trimellitic acid.

<(B) Specific acetamide monomer (sometimes abbreviated as "AA monomer")>
AA2: a compound having the following structure

AA3: Compound with the following structure

AA25: Compound with the following structure

DMAA: A compound with the following structure:

<(C) Acidic Group-Free Polymerizable Monomer (Non-Acidic Monomer)>
Bis-GMA: Bisphenol A di(2-hydroxypropoxy) dimethacrylate; UDMA: Di(methacryloyloxy)-2,2,4-trimethylhexamethylene diurethane; D2.6E: Bisphenol A polyethoxy methacrylate; 3G: Triethylene glycol dimethacrylate; HEMA: 2-hydroxyethyl methacrylate; GDMA: Glycerol dimethacrylate; DEAA: N,N-diethylacrylamide.

<(D) Solvent>
EtOH: ethanol IPA: 2-propanol.

<(E) Polymerization initiator>
CQ: camphorquinone DMBE: p-dimethylaminobenzoic acid ethyl ester BTPO: phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

2. Next, the evaluation methods of the dental adhesives prepared in the Examples and Comparative Examples will be described.
<Preparation of samples for measuring adhesive strength>
Bovine front teeth extracted within 24 hours after slaughter were polished with waterproof abrasive paper P600 under water injection, and the dentin or enamel plane was scraped off so that it was parallel to the labial surface and flat to prepare a substrate.
Next, a double-sided tape with a hole of 3 mm in diameter was attached to the polished surface of each of the two types of adherends. Next, the dental adhesive prepared in each Example and Comparative Example was applied to the adhesive surface of the polished surface exposed through the hole in the double-sided tape, and dried by air blowing for 5 seconds.
A paraffin wax having a thickness of 0.5 mm and a hole having a diameter of 8 mm was attached to the adhesive surface coated with dental adhesive so that the hole of the paraffin wax and the hole of the double-sided tape were concentric to prepare a simulated cavity. The simulated cavity was filled with a dental composite resin (Estelite Σ Quick, manufactured by Tokuyama Dental Co., Ltd.) and lightly pressed with a polyester film, and then photocured by irradiating light for 10 seconds using a visible light irradiator (Elipar, manufactured by 3MESPE Co., Ltd.). Then, a previously polished SUS304 round bar (diameter 8 mm, height 18 mm) was bonded with resin cement (Bistite II, manufactured by Tokuyama Dental Co., Ltd.) to prepare an evaluation sample. The composite resin used was a photopolymerizable composition containing camphorquinone and an amine compound.

<Adhesive strength test>
The samples prepared as described above were immersed in water at 37°C for each Example or Comparative Example for 24 hours, and then the tensile adhesive strength (initial adhesive strength) was measured using a universal testing machine (Shimadzu Autograph) at a crosshead speed of 2 mm/min. The measurement was carried out within about one day after the sample for adhesive strength measurement was taken out of the water. For each Example and Comparative Example, the measured values of four samples were averaged to obtain the measurement result.

3. Examples and Comparative Examples Example 1
(1) Preparation of dental adhesive composition: 0.5g of MDP, 1.5g of AA2, 1.5g of HEMA, 4.0g of Bis-GMA, 2.5g of 3G, 0.2g of CQ, 0.05g of DMBE, 0.5g of EtOH, and 0.4g of water were mixed to obtain a dental adhesive composition.

(2) Adhesion evaluation: The adhesive composition obtained in (1) was used as an adhesive to carry out the above-mentioned adhesion evaluation. The results of using the prepared composition showed that the adhesive strength to enamel was 17.9 MPa and the adhesive strength to dentin was 16.8 MPa, indicating high adhesive strength.

Examples 2 to 19
Adhesive compositions were prepared in the same manner as in Example 1, except that the ratio of each component was changed as shown in Tables 1 and 2, and the adhesive properties were evaluated using the resulting compositions as adhesives. The evaluation results are shown in Tables 1 and 2, and all of the Examples showed sufficiently high adhesive strengths of 10 MPa or more to both enamel and dentin.

Comparative Examples 1 to 9
Except for changing the ratio of each component as shown in Table 2, adhesive compositions were prepared in the same manner as in Example 1, and the adhesive properties were evaluated using the obtained compositions as adhesives. The evaluation results are shown in Table 2. When no acidic monomer was included (Comparative Example 1) and when the content of the acidic monomer was less than 2 parts by mass (Comparative Example 2), the demineralization of the tooth tissue did not proceed sufficiently, and low adhesive strength was shown on both the enamel and dentin. When the content of the acidic monomer was more than 40 parts by mass (Comparative Example 3), the strength of the adhesive layer was insufficient, and low adhesive strength was shown. When no specific acetamide monomer was included (Comparative Examples 2 to 4) and when the content was less than 5 parts by mass (Comparative Example 8), the demineralization of the tooth tissue was insufficient and the adhesive did not penetrate into the tooth tissue sufficiently, and therefore low adhesive strength was shown on both the enamel and dentin. In particular, in the cases of Comparative Examples 2 to 4, which have compositions with a small amount of solvent and disadvantageous to tooth tissue demineralization, the decrease in adhesive strength was remarkable. On the other hand, when the content of the specific acetamide monomer was more than 60 parts by mass (Comparative Example 9), the strength of the adhesive layer was decreased, and low adhesive strength was shown.

Claims (4)

A dental adhesive composition comprising a polymerizable monomer component consisting of an acidic group-containing polymerizable monomer and an acidic group-free polymerizable monomer,
The polymerizable monomer component comprises 2 parts by mass or more and 40 parts by mass or less of the acidic group-containing polymerizable monomer, and the remainder comprises the acidic group-free polymerizable monomer, and the acidic group-free polymerizable monomer is
The following general formulas (1) to (6)
{In the general formulas (1) to (6), n is a natural number from 1 to 30.}
A compound represented by the formula:
The following general formulas (7) to (10)
{In the general formulas (7) to (10), n is a natural number from 1 to 30.}
A compound represented by the formula:
(excluding compounds in which n is 1 in the general formulas (1) to (4) above) in an amount of 5 parts by mass or more and 60 parts by mass or less relative to 100 parts by mass of the polymerizable monomer component,
A dental adhesive composition comprising: 2. The dental adhesive composition according to claim 1, which does not contain a solvent or contains less than 30 parts by weight of a solvent per 100 parts by weight of the polymerizable monomer component. 3. The dental adhesive composition according to claim 1, wherein the amount of the sulfo group-containing polymerizable monomer that can be contained in the acidic group-containing polymerizable monomer is less than 0.1 parts by mass per 100 parts by mass of the polymerizable monomer component. The dental adhesive composition according to claim 3, wherein 98% by mass or more of the acidic group-containing polymerizable monomer is a polymerizable monomer having at least one type of group selected from the group consisting of a carboxyl group (-COOH), a phosphinico group {=P(=O)OH} and a phosphono group {-P(=O)(OH) ₂ } as an acidic group.