JPH0239551B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a new dental adhesive having water resistance. Specifically, a copolymer of a vinyl compound and maleic acid containing 40 mol% to 90 mol% of a radically copolymerizable vinyl compound having a hydrophobic group, and 0.1 per mol of the maleic acid component of the copolymer.
This invention relates to a dental adhesive whose main component is a polyvalent metal salt in an amount of mol to 2.0 mol %. Conventionally, various compounds have been known as dental adhesives, although there are some differences depending on the field of use. Adhesives used in dentistry have particularly demanding properties. As the dental adhesive, for example, an ionomer cement composed of an aqueous polyacrylic acid solution and an inorganic oxide, and a room temperature-curable adhesive using a polymerizable monomer are known. However, although ionomer cement has adhesive strength with tooth structure, it has the disadvantage that it does not have adhesive strength with other dental filling materials and has low water resistance, so it easily comes off in water. Furthermore, adhesives using polymerizable monomers adhere to enamel, but hardly adhere to dentin. For this reason, it was necessary to demineralize the tooth substance by previously treating it with a high-concentration phosphoric acid aqueous solution and create a mechanical retention form. However, this method has the disadvantage that it damages even healthy tooth tissue because it uses highly concentrated phosphoric acid, and furthermore, unreacted monomers cause damage to the dental pulp. The present inventors have conducted extensive research in order to develop an adhesive composition that does not have the above-mentioned drawbacks, particularly an adhesive composition that is effective for dental applications. As a result, it adheres directly to the tooth dentin without pre-treatment with a phosphoric acid aqueous solution.
Moreover, they have discovered a new adhesive composition that does not cause dental pulp damage due to unreacted monomers, and have now provided the present invention. That is, the present invention provides (a) a copolymer of a vinyl compound having a hydrophobic group and capable of radical copolymerization, which contains 40 mol% or more to 90 mol% of said vinyl compound and maleic acid, and (b) said copolymer. This is a dental adhesive whose main component is a polyvalent metal salt in an amount of 0.1 to 2.0 moles per mole of maleic acid component. One component of the dental adhesive of the present invention is a copolymer of a radically copolymerizable vinyl compound having a hydrophobic group and maleic acid. It is necessary that the vinyl compound serving as a raw material for the copolymer has a hydrophobic group and is capable of radical copolymerization. The hydrophobic group is not particularly limited, and known ones can be used.
Typical hydrophobic groups that are generally suitably used include aromatic rings such as phenyl and naphthyl groups; alkyl groups such as methyl, ethyl and propyl groups; alkyl ester groups; long-chain alkyl ethers. These are the basics. Further, the radical copolymerization is not particularly limited, and polymerization carried out using the following polymerization initiator is generally employed. For example, organic peroxides such as benzoyl peroxide and lauroyl peroxide, azo compounds such as azobisisobutyronitrile, organometallic compounds such as tributylboron, or metals using redox initiators can be suitably used. Furthermore, any known vinyl compound capable of radical copolymerization may be used without particular limitation. Specific examples of generally suitable vinyl compounds include styrene, methylstyrene, stilbene, vinylnaphthalene, butene, butadiene, vinyl acetate, allyl acetate, and isobutyl vinyl ether. Further, these vinyl compounds can be used alone or in combination. The copolymer used in the present invention has the vinyl compound and maleic acid as main components, and the vinyl compound component contained in the copolymer is preferably 40 mol% or more and 90 mol% or less. . If the amount of the vinyl compound exceeds mol %, adhesive strength to the tooth structure cannot be obtained. Although the reason for this is not clear at present, it is presumed that the copolymer has a high hydrophobic group and thus has a low affinity with tooth structure. In addition, copolymers containing less than 40 mol% of the vinyl compound are generally difficult to produce industrially because maleic acid has poor polymerizability, and the copolymers obtained are not only difficult to produce in dental applications but also The water resistance of the adhesive tends to be insufficient. Therefore, the above-mentioned components of the copolymer used in the present invention have an important meaning. Another component of the copolymer used in the present invention is maleic acid. The maleic acid is not limited to merely using a maleic acid monomer during copolymerization, but it is sufficient that the resulting copolymer has a maleic acid component bound thereto. Therefore, a maleic acid monomer can be used in the above-mentioned copolymerization, but for example, a method of imparting maleic acid to the copolymer through post-treatment as described below can also be adopted. For example, a copolymer is produced by radical copolymerization of the vinyl compound and maleic anhydride or maleic diester, and then the maleic anhydride group or maleic diester in the copolymer is hydrolyzed. A method of converting it into a maleic acid group can be suitably employed. The method of hydrolysis is not particularly limited, but generally a copolymer containing a maleic anhydride group or a maleic acid diester is dissolved in a suitable organic solvent, and water and an acid or acid are added as a promoter of the hydrolysis reaction. A method in which a small amount of an alkali component is added and the reaction is carried out at room temperature or under heating is preferred. Furthermore, the copolymer used in the present invention is a copolymer of a radically copolymerizable vinyl compound having a hydrophobic group and maleic acid, but in addition to these two components, it also has physical properties required for a dental adhesive. Other copolymerizable monomers can also be copolymerized as long as they can be used. The polyvalent metal salt used in the present invention is not particularly limited, and known polyvalent metal salts having a valence of two or more can be used.
In particular, considering that the dental adhesive of the present invention is useful for dental purposes, the polyvalent metal salt is preferably one that is less harmful to the human body. Generally, halides, sulfates, nitrates, organic acid salts, etc. of calcium, aluminum, ferric iron, etc. are particularly preferably used alone or in combination. The amount of these polyvalent metal salts used is the maleic acid component 1 of the copolymer.
It is added at a ratio of 0.1 to 2.0 moles per mole. If the amount of the polyvalent metal salt added is less than 0.1 mol, the water resistance of the dental adhesive may decrease, and the field of use may be restricted. Furthermore, if the amount of the polyvalent metal added exceeds 2.0 mol, the operability during adhesion may deteriorate, and the field of use may be limited. Although the causal relationship between the amount of the polyvalent metal salt added and the water resistance of dental adhesives is currently not necessarily clear, it is possible that the maleic acid groups in the copolymer react with the polyvalent metal. In this case, it is presumed that the polyvalent metal salt acts as a crosslinking agent. Therefore, in the present invention, each addition ratio of the dental adhesive is preferably determined in advance depending on the physical properties required in the field in which the adhesive is used. The method of mixing the copolymer and the polyvalent metal salt in the present invention is not particularly limited, but a method of mixing in the presence of an organic solvent is most preferably used. When using an organic solvent that does not contain water, the copolymer and the polyvalent metal salt may be mixed in advance or may be mixed at the time of use. This is because the copolymer and polyvalent metal salt are difficult to react in an organic solvent. For example, when this liquid is applied to the tooth surface, the metal salt is first ionized by the moisture on the surface of the tooth, and hardening occurs due to crosslinking. The organic solvent is not particularly limited as long as it dissolves the copolymer and/or polyvalent metal salt, but ethanol, acetone, etc., which generally have a low boiling point and can be easily removed, are preferably used. It will be done. The dental adhesive of the present invention can obtain sufficient adhesive strength only from the copolymer and polyvalent metal salt, but it can also be cured in the coexistence of a monomer and an initiator capable of crosslinking polymerization. . The monomer capable of crosslinking polymerization is not particularly limited, and known monomers can be used. For example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol,
Diacrylic esters and dimethacrylic esters such as butylene glycol; triacrylic esters and trimethacrylic esters such as trimethylolpropane and trimethylolethane; tetraacrylic esters and tetraacrylic esters such as tetramethylolmethane; Bisphenol-A-diglycidyl methacrylate and the like are preferably used. Although the initiator is not particularly limited, it is generally preferable to use a mixed system of peroxide and amine. The peroxide may be any peroxide commonly used as a curing agent, and dibenzoyl peroxide, dilauroyl peroxide, etc. are particularly preferably used. In addition, the amines include N,N'-dimethylaniline, N,
N'-dimethyl-P-toluidine, N-methyl,
N'-β-hydroxyethyl-aniline, N,
N'-dimethyl-P-(β-hydroxyethyl)
-Aniline, N,N'-di(β-hydroxyethyl)-P-toluidine, etc. are preferably used. Furthermore, in addition to the above-mentioned initiators, co-catalysts such as sulfinates can also be used. As is clear from the above description, the adhesive of the present invention can be used in dentistry to firmly bond tooth structure and filling material under moist conditions without phosphoric acid etching of the tooth structure in advance. That is, the adhesive of the present invention exhibits a suitable adhesive effect particularly when used in a humid environment, and thus becomes an excellent dental adhesive. EXAMPLES In order to explain the present invention more specifically, Examples will be described below, but the present invention is not limited to these Examples. Production example 1 Put 200 ml of cyclohexane into a 500 ml separable glass flask, and add 5.2 ml of styrene to it.
g, 4.9 g of maleic anhydride and 0.05 g of benzoyl peroxide (hereinafter abbreviated as BPO) were added and thoroughly stirred. Next, after reducing the pressure in the container and purging it with nitrogen, heating polymerization was carried out at 80°C for 4 hours with stirring, and after cooling to room temperature, the formed precipitate was filtered off.
The obtained solid was further thoroughly washed with 300 ml of benzene and then dried to obtain 8.7 g of a white polymer. As a result of elemental analysis of this product, the composition of the copolymer produced was determined to be 48.4 mol of styrene, maleic anhydride,
It was 51.6 mol%. Next, dissolve this product in 80 ml of dioxane, add it to a 500 ml flask, and while stirring thoroughly, add 5% by weight aqueous potassium hydroxide solution.
100 ml was added and allowed to react at room temperature for 10 hours. Next, concentrated hydrochloric acid was added to neutralize the mixture, and an excess of hydrochloric acid was further added to obtain a white solid precipitate. This solid was filtered off, washed with water repeatedly until it became neutral, and further dried to obtain 8.0 g of a copolymer. As a result of measuring the infrared absorption spectrum of this product, we found that the characteristic absorption (1850
cm ^-1 , 1775cm ^-1 ) completely disappeared, and a new characteristic absorption derived from the carbonyl group of maleic acid appeared at 1720cm ^-1
It was confirmed that the hydrolysis reaction was proceeding almost quantitatively. That is, the white solid obtained above contains 48.4 mol% styrene and maleic acid.
It was confirmed that the copolymer contained 51.6 mol%. Production Examples 2-3 As a styrene-maleic anhydride copolymer
Using two types of commercially available products (manufactured by Arco Chemical) with different compositions shown in Table 1, hydrolysis was carried out in the same manner as in Production Example 1. A styrene-maleic acid copolymer having the same composition as shown in Table 1 was obtained from the measurement results of absorption spectra.

[Table] Production Example 4 Add 50 ml of benzene containing 35 g of maleic anhydride and 90 mg of azobisisobutyronitrile (hereinafter abbreviated as AIBN) to a 300 ml pressure-resistant glass container, and cool in a dry ice-methanol bath. At the same time, the contents were purged with nitrogen under reduced pressure, and then 12 g of purified propylene was added by distillation through a liquefaction meter. Next, stirring was continued for 36 hours at 60°C to carry out copolymerization. After the polymerization was completed, the contents were poured into a large amount of anhydrous ether to precipitate the resulting copolymer, thoroughly washed by a decanting method, and immediately dried in a vacuum dryer. The yield was 60%. Elemental analysis revealed that maleic anhydride was 55.6 mol% and propylene was 44.4 mol%. Next, this product was hydrolyzed in the same manner as in Production Example 11 to obtain propylene-maleic acid copolymer 24.2
I got g. As a result of measuring the infrared absorption spectrum of this copolymer, it was confirmed that the maleic anhydride groups in the raw material were almost quantitatively converted to maleic acid. Production Example 5 50 ml of benzene containing 35.7 g of maleic anhydride and 90 mg of AIBN is added to a 300 ml pressure glass container. To this, 12.5 g of isobutene was charged by distillation through a liquefaction meter, and then copolymerization was carried out at 60° C. for 15 minutes. After the polymerization is complete, the contents are poured into a large amount of anhydrous ether to precipitate the resulting copolymer,
The supernatant is discarded by the decanting method, thoroughly washed with anhydrous ether, and then dried under reduced pressure. The yield was 43.3%. . This material was found to be isobutene based on elemental analysis.
It was a copolymer containing 47.1 mol% of maleic anhydride and 52.9 mol% of maleic anhydride. Next, this product was hydrolyzed in the same manner as in Production Example 1 to obtain 20.5% of isobutene-maleic acid copolymer.
I got g. As a result of measuring the infrared absorption spectrum of this copolymer, it was confirmed that the maleic anhydride groups in the raw material were almost quantitatively converted to maleic acid. Example 1 The following adhesion test was conducted using the styrene-maleic acid copolymers synthesized in Examples 1 to 3.
First, the surface of a freshly extracted bovine tooth was polished with emery paper (#320) to expose the smooth dentin.
After washing with water, the surface was dried by blowing nitrogen gas. Then, a wax plate with holes of 6 mm in inner diameter and 2 mm in thickness was attached to the dry surface using double-sided tape. Next, an ethanol solution of a styrene-maleic acid copolymer and an ethanol solution of a polyvalent metal chloride shown in Table 2 were mixed, and then applied to the tooth surface surrounded by a plate-shaped wax and dried with nitrogen gas. A commercially available dental composite resin restorative material (manufactured by Johnson & Johnson, trade name: Adapt) was filled thereon according to the prescription. After being left for 1 hour, the plate-like wax was removed, and after being immersed in water at 37°C for 24 hours, the tensile strength was measured. Tensilon manufactured by Toyo Baldwin Co., Ltd. was used for the measurement, and the tensile speed was 2 mm/min. The results were as shown in Table 2. The adhesion test was conducted using 10 bovine teeth each, and the percentage of samples that remained intact even after being immersed in water at 37°C for 24 hours, as well as the average bond strength measured by the tensile test. The values are shown in Table 2.

[Table] Shows the percentage of samples.
Example 2 A method similar to Example 1 using a tetrahydrofuran solution of the propylene-maleic acid copolymer synthesized in Production Examples 4 to 5 or a tetrahydrofuran solution of the isobutene-maleic acid copolymer and an ethanol solution of ferric chloride. An adhesion test was conducted. Also,
The measurement of adhesive strength was also the same as in Example 1. The results were as shown in Table 3.

[Table] Comparative Example 1 Two types of commercially available dental bonding agents and one type of carboxylate cement were examined for adhesive strength with bovine dentin. The bonding method was the same as in Example 1. Commercially available bonding agents were filled using filling materials from the same company according to the instructions for use. Regarding carboxylate cement, No. 3 in Table 4 is the one in which the cement was directly filled, and No. 4 in Table 4 is the one in which the cement was diluted 5 times with water and applied to the dentin. Measurements were carried out on the product filled with Adapter. The results are shown in Table 4.

[Table] Comparative Example 2 A metal salt/copolymer was prepared using an ethanol solution of acrylic acid (56%)-itaconic acid (32%)-maleic acid (12%) copolymer and an ethanol solution of ferric chloride. An adhesion test was conducted in the same manner as in Example 1, except that the mixture was mixed at a concentration of 25 (wt%). As a result, all 10 bonded samples were tested in water at 37℃.
The dental composite resin restoration material peeled off after being soaked for 24 hours.

Claims (1)

[Scope of Claims] 1. (a) A copolymer of a vinyl compound and maleic acid containing 40 mol% to 90 mol% of a radically copolymerizable vinyl compound having a hydrophobic group, and (b) the copolymer. 0.1 mol to 1 mol of maleic acid component of the combined product
A dental adhesive whose main ingredient is 2.0 mol of polyvalent metal salt. 2. The dental adhesive according to claim 1, wherein the copolymer and the polyvalent metal salt are mixed in an organic solvent. 3. The dental adhesive according to claim 1, wherein the copolymer is soluble in an organic solvent. 4. The dental adhesive according to claim 1, wherein the polyvalent metal salt is soluble in an organic solvent.