Dental cement composition

Abstract

To provide a dental cement composition that combines ease of handling and storage stability, allowing it to maintain a semi-hardened state suitable for removing excess cement for a long period even after long-term storage. [Solution] The dental cement composition of the present invention comprises: polymerizable monomer (A): 100 parts by mass; filler (B): 50 parts by mass or more and 500 parts by mass or less; α-diketone compound (C); organic peroxide (D); and tertiary aromatic amine composition (E). The tertiary aromatic amine composition (E) comprises a first tertiary aromatic amine (e1) represented by general formula (1), a second tertiary aromatic amine (e2) represented by general formula (2), and a third tertiary aromatic amine (e3) represented by general formula (3).

Description

[Technical Field]

[0001] The present invention relates to a dental cement composition for bonding teeth to prostheses. [Background technology]

[0002] Teeth that have lost function due to caries, accidents, etc., are restored by fixing restorative materials made of metal or ceramic, such as inlays or crowns, to the area where function has been lost. An adhesive material called dental cement is used to fix the restorative materials to the tooth.

[0003] Dental cement is obtained by hardening a dental cement composition. A dental cement composition mainly contains a mixture of polymerizable monomers and fillers, and further contains a polymerization initiator to polymerize and harden the polymerizable monomers. Dental cement compositions are broadly classified into three types depending on the type of polymerization initiator used: photopolymerization type using a photopolymerization initiator, chemical polymerization type using a chemical polymerization initiator, and dual-cure type using both polymerization initiators.

[0004] The procedure for fixing a dental crown to a tooth involves first applying an excess amount of uncured dental cement to the crown and pressing it against the tooth structure. At this time, the excess dental cement will protrude from the margin, which is the joint between the tooth structure and the crown, so this excess cement is removed. After removing the excess cement, if it is a light-curing type, it is exposed to light again to further advance the light-curing process; if it is a chemical-curing type, it is left to stand for a while to allow the chemical polymerization to proceed; and if it is a dual-cure type, either the light-curing or chemical polymerization method is selected to complete the hardening of the dental cement.

[0005] This excess cement is scraped off using a dental probe or similar tool. However, this method is difficult to use if the excess cement is not yet hardened and is highly fluid, or if it has completely hardened. Therefore, the excess cement is usually removed when it has hardened to a certain extent and lost some of its fluidity (i.e., when it is semi-hardened).

[0006] However, maintaining a semi-cured state was difficult, especially in the case of photopolymerization, where the reaction was too fast. Even a slightly longer irradiation time would cause the excess cement to harden completely, making it impossible to remove. This made controlling the irradiation time difficult and resulted in poor workability.

[0007] To address the aforementioned problem of removing excess cement, Patent Document 1 discloses a technique in which three different tertiary aromatic amines are used as co-catalysts in combination with an α-diketone compound as a photopolymerization initiator. This allows for a slower photopolymerization rate while maintaining polymerization activity until the end, making it possible to maintain a semi-cured state for a longer period without changing the physical properties such as the strength of the final cured product. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2012-162490 [Overview of the project] [Problems that the invention aims to solve]

[0009] Generally, dental cement compositions are intended for long-term storage and require storage stability. However, it has been found that the dental cement described in Patent Document 1 changes in performance after long-term storage, failing to maintain a semi-hardened state suitable for removing excess cement for an extended period, resulting in poor handling during use.

[0010] In view of the above circumstances, the present invention aims to provide a dental cement composition that has excellent operability and storage stability that maintains that operability. [Means for solving the problem]

[0011] To achieve the above objective, a dental cement composition according to one embodiment of the present invention comprises: polymerizable monomer (A): 100 parts by mass; filler (B): 50 parts by mass or more and 500 parts by mass or less; α-diketone compound (C); organic peroxide (D); and tertiary aromatic amine composition (E). The above tertiary aromatic amine composition (E) comprises a first tertiary aromatic amine (e1) represented by the following general formula (1), a second tertiary aromatic amine (e2) represented by the following general formula (2), and a third tertiary aromatic amine (e3) represented by the following general formula (3). [ka] (In the formula, R1 and R2 are each independently alkyl groups having 1 to 6 carbon atoms, R3 is an alkyloxycarbonyl group, and n is an integer from 1 to 3.) [ka] (In the formula, R4 and R5 are each independently a C1-C6 alkyl group or a C1-C6 alkyl group having a substituent selected from a hydroxyl group, a nitro group, a sulfonic acid group, and a halogen atom; at least one of R4 and R5 is a C1-C6 alkyl group having the substituent; R6 is a C1-C4 alkyl group; and m is an integer from 0 to 3.) [ka] (In the formula, R7 is a t-butyl group or a hydroxyalkyl group having 1 to 4 carbon atoms.)

[0012] In the third tertiary aromatic amine (e3) represented by the general formula (3) used in the present invention, for the substituent R7 on the aromatic ring, a substituent with a high molecular weight is adopted, and for the substituent on the N atom, a substituent with a low molecular weight is adopted. Specifically, for the substituent R7 on the aromatic ring, by adopting a t-butyl group with a high molecular weight, the boiling point becomes high, and also, by adopting a hydroxyalkyl group having 1 to 4 carbon atoms with a high molecular weight, it becomes solid, and it is possible to suppress the deterioration over time of components such as decomposition and volatilization that occur during long-term storage. On the other hand, for the substituent on the N atom, by adopting a methyl group with a low molecular weight, it is possible to suppress the decrease in the photopolymerization rate caused by a high molecular weight and maintain a semi-cured state suitable for removing excess cement. According to the dental cement composition of the present invention containing such a third tertiary aromatic amine (e3), excellent operability and storage stability capable of maintaining such operability can be realized.

[0013] The above α-diketone compound (C): 0.01 part by mass or more and 5 parts by mass or less, the above organic peroxide (D): 0.01 part by mass or more and 5 parts by mass or less, and the above tertiary aromatic amine composition (E): 0.01 part by mass or more and 10 parts by mass or less, and in the above first, second, and third tertiary aromatic amines, the mass ratio represented by (e1):(e2):(e3) may be 1:1 to 5:0.1 to 2.

[0014] The above first tertiary aromatic amine (e1) may be ethyl 4-dimethylaminobenzoate or methyl 4-dimethylaminobenzoate. [[ID=X]]The above second tertiary aromatic amine (e2) may be p-tolyldiethanolamine or N,N-di(2-hydroxypropyl)-p-toluidine. The above third tertiary aromatic amine (e3) may be 4-t-butyl-N,N-dimethylaniline or 2-[4-(dimethylamino)phenyl]ethanol.

Advantages of the Invention

[0015] According to the present invention, it is possible to provide a dental cement composition having excellent operability and storage stability capable of maintaining such operability.

Best Mode for Carrying Out the Invention

[0016] In this specification, a numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value.

[0017] [Summary of the Invention] The dental cement composition of the present invention contains a polymerizable monomer (A): 100 parts by mass, a filler (B): 50 parts by mass or more and 500 parts by mass or less, an α-diketone compound (C), an organic peroxide (D), and a tertiary aromatic amine composition (E).

[0018] The dental cement composition of the present invention is used as a dual-cure type dental cement capable of curing the polymerizable monomer (A) by photopolymerization and chemical polymerization. The α-diketone compound (C) acts as a photoinitiator that initiates the polymerization of the polymerizable monomer (A) by irradiating visible or ultraviolet light, and the organic peroxide (D) acts as a chemical initiator (oxidizing agent) that generates radicals using a redox reaction. The tertiary aromatic amine composition (E) is used to adjust the rate of chemical polymerization and the rate of photopolymerization so as to maintain a semi-cured state suitable for removing excess cement.

[0019] The tertiary aromatic amine composition (E) includes a first tertiary aromatic amine (e1) represented by the following general formula (1) (hereinafter also referred to as the "(e1) component"), a second tertiary aromatic amine (e2) represented by the following general formula (2) (hereinafter also referred to as the "(e2) component"), and a third tertiary aromatic amine (e3) represented by the following general formula (3) (hereinafter also referred to as the "(e3) component"). Each of the (e1) component, the (e2) component, and the (e3) component acts as a co-catalyst in combination with a photoinitiator. Further, the (e2) component and the (e3) component also act as chemical initiators (reducing agents). [Chemical Formula] (In the formula, R1 and R2 are each independently alkyl groups having 1 to 6 carbon atoms, R3 is an alkyloxycarbonyl group, and n is an integer from 1 to 3.) [ka] (In the formula, R4 and R5 are each independently a C1-C6 alkyl group or a C1-C6 alkyl group having a substituent selected from a hydroxyl group, a nitro group, a sulfonic acid group, and a halogen atom; at least one of R4 and R5 is a C1-C6 alkyl group having the substituent; R6 is a C1-C4 alkyl group; and m is an integer from 0 to 3.) [ka] (In the formula, R7 is a t-butyl group or a hydroxyalkyl group having 1 to 4 carbon atoms.)

[0020] First, we will explain the mechanism of radical generation by light irradiation of the first to third tertiary aromatic amines (components (e1) to (e3)) used in this invention.

[0021] Generally, the reaction between a tertiary amine and an α-diketone compound proceeds as shown in the following chemical equation. Here, camphorquinone (CQ) is used as the α-diketone compound. Also, the tertiary amine is (R a )(R b )N-CH2R c As shown, for example, R a R is an aromatic ring, b and R cCQ is an alkyl group. When visible light is irradiated onto this CQ and tertiary aromatic amine, in the first step, (i) an excyplex (a complex of the excited state of CQ and the tertiary amine) is formed. Then, in the second step, after electron transfer within the excyplex, (ii) a hydrogen abstraction reaction occurs from the tertiary amine, generating a radical. Components (e1) to (e3) of the present invention differ in their structural differences, resulting in different reaction rates for (i) the formation of the excyplex and (ii) the hydrogen abstraction reaction. Consequently, components (e1) to (e3) exhibit different functions. [ka]

[0022] Specifically, component (e1), when it forms an excyplex with the α-diketone compound (C), is the most active radical generator among the three, and is the main component that promotes photopolymerization. Component (e1) has a high energy requirement (activation energy) for forming an excyplex with the α-diketone compound (C), making the formation of this excyplex relatively difficult. However, it readily undergoes a hydrogen abstraction reaction, generating radicals actively and initiating polymerization with high activity. Therefore, in dental cement compositions using only component (e1), the photopolymerization rate is increased, and the strength of the final hardened product can be improved. However, on the other hand, because the semi-hardened state is extremely short, it is unavoidable that there is insufficient time to remove excess cement.

[0023] Component (e2) requires less energy (activation energy) to form the (i) excyplex compared to component (e1). Therefore, when components (e1) and (e2) are used in combination, component (e2) preferentially forms the (i) excyplex. On the other hand, the (ii) hydrogen abstraction reaction of component (e2) proceeds more slowly than that of component (e1), resulting in slower radical generation and significantly delaying the full-scale curing by component (e1). As a result, the semi-cured state can be maintained for a longer period, but at the beginning of light irradiation, radical generation becomes extremely difficult, leading to a problem where the time to reach the semi-cured state is significantly delayed.

[0024] Component (e3), like component (e2), has a low energy requirement (activation energy) for forming (i) an excyplex. Therefore, it preferentially forms (i) an excyplex more readily than component (e1), while its (ii) hydrogen abstraction reaction is nearly as active as that of component (e1). Consequently, by using component (e3) in addition to components (e1) and (e2), a semi-cured state can be reached with short-term light irradiation, and this state can be maintained for a longer period.

[0025] Furthermore, both component (e2) and component (e3) only have a slower hydrogen abstraction reaction compared to component (e1), and do not trap radicals like polymerization inhibitors, so they do not hinder the final curing. Therefore, if sufficient curing time is ensured, a cured body as strong as that obtained when using component (e1) alone can be obtained.

[0026] Under the above mechanism, it became clear that while conventional dental cement compositions provided good handling properties immediately after preparation, their initial performance could not be maintained after long-term storage. In response to this, the inventors conducted extensive research and found that tertiary aromatic amine components with high molecular weight substituents and solid properties at room temperature (e.g., components (e1) and (e2), etc.) did not deteriorate significantly even after long-term storage, whereas tertiary aromatic amine components with low molecular weight and liquid properties at room temperature decomposed and volatilized over time, resulting in a loss of performance. Based on this, the inventors investigated increasing the molecular weight of substituents in component (e3) of the present invention. As a result, they found that rather than simply increasing the molecular weight of substituents in component (e3), increasing the molecular weight of substituent R7 on the aromatic ring using a specific substituent, thereby raising the boiling point of component (e3), or changing the properties of component (e3) from liquid to solid at room temperature, made it less susceptible to deterioration over time. On the other hand, we found that by using a low molecular weight methyl group instead of a high molecular weight group as the substituent on the N atom, the decrease in the photopolymerization rate can be suppressed, and the semi-cured state can be maintained for a longer period. The dental cement composition obtained in this way according to the present invention is excellent in both operability suitable for removing excess cement and storage stability while maintaining its performance.

[0027] The substituent R7 on the aromatic ring of component (e3) of the present invention is characterized by being a t-butyl group or a hydroxyalkyl group having 1 to 4 carbon atoms. Because substituent R7 is a substituent with a high molecular weight, deterioration of component (e3) over time can be suppressed even after long-term storage. Here, if substituent R7 on the aromatic ring is a low molecular weight methyl group, for example, it is a liquid at room temperature, and its boiling point remains at around 211°C. In contrast, if substituent R7 on the aromatic ring is a t-butyl group, the boiling point exceeds 250°C, and if substituent R7 on the aromatic ring is a hydroxyalkyl group having 1 to 4 carbon atoms, it becomes a solid at room temperature, suppressing deterioration over time such as decomposition and volatilization. This is presumed to be because the intermolecular interactions are strengthened by van der Waals forces due to the t-butyl group and hydrogen bonds due to the hydroxyalkyl group having 1 to 4 carbon atoms, raising the boiling point and further suppressing deterioration over time such as decomposition and volatilization of the component.

[0028] Furthermore, the two substituents on the N atom of component (e3) are both methyl groups. This suppresses the decrease in the photopolymerization reaction that occurs when using substituents with high molecular weight, and maintains a good semi-cured state suitable for removing excess cement.

[0029] The mechanism is explained below. When the two substituents on the N atom are methyl groups, for example, photopolymerization proceeds as shown in the chemical reaction equation below. As the first step of photopolymerization, a radical is generated on the carbon atom adjacent to the N atom by (i) excyplex formation with the α-diketone compound (C) camphorquinone (CQ) followed by (ii) hydrogen abstraction. At this time, since the substituents on the N atom are methyl groups, the generated radical is an unstable and highly reactive primary radical (- · This is CH2. Then, in the second step, the addition reaction of the primary radical to CH2=CH(CH3)COOR (polymerizable monomer) proceeds rapidly. As a result, hardening proceeds quickly after light irradiation, and the removal of excess cement can be started immediately. [ka]

[0030] In contrast, when the substituent on the N atom is a large alkyl group with 2 or more carbon atoms, photopolymerization proceeds as shown in the chemical reaction equation below. In the first step, as above, (i) excyplex formation with the α-diketone compound (C) camphorquinone (CQ) occurs, followed by (ii) hydrogen abstraction. However, in the case of an alkyl group with 2 or more carbon atoms on the N atom, the generated radical is a secondary radical (- · It is a CH2CH2R' radical, which is more stable and less reactive than a primary radical. Therefore, in the subsequent second step, the addition reaction to the polymerizable monomer is slowed down, and photopolymerization does not proceed rapidly. This results in a decrease in the rate of photopolymerization. [ka]

[0031] Thus, in component (e3) of the present invention, a high molecular weight substituent is used at substituent R7 of the aromatic ring, and a low molecular weight methyl group is used instead of a high molecular weight group at the substituent on the N atom. This suppresses the deterioration of the component over time and the decrease in the photopolymerization rate, allowing a semi-cured state suitable for removing excess cement to be maintained for a long time both immediately after preparation and after long-term storage, resulting in a dental cement composition with excellent handling properties during use and storage stability.

[0032] The components of the dental cement composition of the present invention will be described in detail below.

[0033] [Detailed Configuration of the Invention] (Polymerizable monomer (A)) In the present invention, polymerizable monomer (A) can be any known monomer without particular limitations, but a radical polymerizable monomer is usually preferred. Examples of radical polymerizable unsaturated groups possessed by a radical polymerizable monomer include (meth)acryloyl groups such as (meth)acryloyl groups, (meth)acryloyloxy groups, (meth)acryloylamino groups, and (meth)acryloylthio groups, as well as vinyl groups, allyl groups, and styryl groups.

[0034] From the standpoint of polymerizability and biosafety, radical polymerizable monomers, such as (meth)acrylic acid ester-based radical polymerizable monomers, are preferably used. Specific examples are as follows.

[0035] (1) Monofunctional polymerizable monomers Examples of monofunctional polymerizable monomers include ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, n-lauryl (meth)acrylate, tridecyl (meth)acrylate, n-stearyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 3-hydroxypropyl (meth)acrylate. Examples include alkyl esters of (meth)acrylic acid such as tetrahydrofurfuryl (meth)acrylate or glycidyl (meth)acrylate, fluorine-containing (meth)acrylates such as 1H,1H,3H-hexafluorobutyl methacrylate, 1H,1H,5H-octafluoropentyl methacrylate, 1H,1H,6H-decafluorohexyl methacrylate or 1H,1H,7H-dodecafluoroheptyl methacrylate, or (meth)acrylates.

[0036] (2) Bifunctional polymerizable monomer Examples of difunctional polymerizable monomers (A) include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 2,2-bis((meth)acryloxyphenyl)propane, 2,2-bis[4-(3-(meth)acryloxyethoxy)-2-hydroxypropoxyphenyl]propane, 2,2-bis(4-(meth)acryloxyethoxyphenyl)propane, 2,2 -Bis(4-(meth)acryloxydiethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxytetraethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxypentaethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxydipropoxyphenylpropane, 2-(4-methacryloxyethoxyphenyl)-2-(4-(meth)acryloxydiethoxyphenyl)propane, 2-( Examples include 4-(meth)acryloxydiethoxyphenyl)-2-(4-(meth)acryloxytriethoxyphenyl)propane, 2-(4-(meth)acryloxydipropoxyphenyl-2-(4-(meth)acryloxytriethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxypropoxyphenyl)propane, or 2,2-bis(4-(meth)acryloxyisopropoxyphenyl)propane.

[0037] (3) Trifunctional polymerizable monomer Examples of trifunctional polymerizable monomers (A) include trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, pentaelsritol tri(meth)acrylate, or trimethylolmethane tri(meth)acrylate.

[0038] (4) Tetrafunctional polymerizable monomer Examples of tetrafunctional polymerizable monomers include pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, or pentaerythritol hexa(meth)acrylate.

[0039] Furthermore, among the above-mentioned polymerizable monomers that do not contain acidic groups, polymerizable monomers with two or more functionalities are preferred from the viewpoint of mechanical strength.

[0040] In the present invention, the polymerizable monomers described above may be used alone, or two or more polymerizable monomers may be used in combination. Furthermore, multiple polymerizable monomers with different numbers of functional groups may be combined.

[0041] (Filler (B)) In this invention, the filler (B) added to the cement improves the strength of the cement and suppresses shrinkage during polymerization. Furthermore, the viscosity (workability) of the cement before hardening can be adjusted by changing the amount of filler (B) added. As filler (B), one or more types selected from inorganic fillers, organic fillers, and organic-inorganic composite fillers can be used as appropriate.

[0042] Specific examples of organic fillers used in the present invention include non-crosslinkable polymers such as polymethyl (meth)acrylate, polyethyl (meth)acrylate, methyl (meth)acrylate-ethyl (meth)acrylate copolymer, methyl (meth)acrylate-butyl (meth)acrylate copolymer, or methyl (meth)acrylate-styrene copolymer, or (meth)acrylate polymers such as methyl (meth)acrylate-ethylene glycol di(meth)acrylate copolymer, methyl (meth)acrylate-triethylene glycol di(meth)acrylate copolymer, or copolymer of methyl (meth)acrylate and a butadiene monomer. Mixtures of two or more of these can also be used.

[0043] Specific examples of inorganic fillers used in the present invention include quartz, silica, silica-titania, silica-zirconia, lanthanum glass, barium glass, strontium glass, sodium fluoride, calcium carbonate, aluminum silicate, and fluoroaluminosilicate glass. Two or more of these can also be used in combination.

[0044] Furthermore, organic-inorganic composite fillers can also be suitably used. For example, a granular organic-inorganic composite filler can be obtained by pre-adding a polymerizable monomer to an inorganic filler, forming a paste, polymerizing it, and then grinding it. Examples of organic-inorganic composite fillers that can be used include TMPT filler (a mixture of trimethylolpropane methacrylate and silica filler that has been polymerized and then ground).

[0045] The inorganic fillers or organic-inorganic composite fillers described above can be treated with surface treatment agents, such as silane coupling agents, to improve their affinity with polymerizable monomers (A), their dispersibility on polymerizable monomers (A), and the mechanical strength and water resistance of the cured product. Such surface treatment agents are not limited in any way, and known agents can be used. Surface treatment methods using these agents can also be based on known methods.

[0046] Suitable silane coupling agents used for surface treatment of basic inorganic materials include methyltrimethoxysilane, methyltriethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, γ-methacryloyloxypropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, or hexamethyldisilazane. In addition to silane coupling agents, surface treatment of basic inorganic materials can also be performed using titanate-based coupling agents, aluminate-based coupling agents, zircoaluminate-based coupling agents, or by graft polymerization of the polymerizable monomer onto the surface of filler particles.

[0047] The particle size and shape of the filler (B) are selected as appropriate, but the average particle size is usually 0.001 to 50 μm, and from the viewpoint of compatibility with the prosthesis, it is particularly preferable that it be 0.001 to 10 μm.

[0048] The amount of filler (B) is preferably in the range of 50 to 500 parts by mass per 100 parts by mass of polymerizable monomer (A). Particularly preferably, it is 150 to 400 parts by mass per 100 parts by mass of polymerizable monomer (A). If the amount of filler (B) is less than 50 parts by mass, sufficient strength as a cement cannot be obtained, and if it is added in excess of 500 parts by mass, the viscosity will increase, making it difficult to mix and resulting in poor handling, or the cement may become too thick, resulting in poor fit with the prosthesis.

[0049] (α-diketone compound (C)) The photopolymerization initiator of the present invention can be used without particular limitations, as long as it can form an excyplex with a tertiary aromatic amine and initiate polymerization of a polymerizable monomer (A) by irradiation with visible or ultraviolet light.

[0050] Specific examples include diacetyl, acetylbenzoyl, benzyl, 2,3-pentadione, 2,3-octadione, 4,4'-dimethoxybenzyl, 4,4'-oxybenzyl, camphorquinone, 9,10-phenanthrenequinone, acenaphthenequinone, 4,4'-dichlorobenzyl, α-cyclohexanedione, camphorquinone-10-sulfonic acid, and camphorquinone-10-carboxylic acid.

[0051] These photopolymerization initiators may be used individually or in combination of two or more. Among the above photopolymerization initiators, camphorquinone and benzyl are preferred from the viewpoint of polymerization activity and harm to living organisms.

[0052] Furthermore, the amount of α-diketone compound (C) is not particularly limited, but from the viewpoint of hardening properties, it is preferably in the range of 0.01 to 5 parts by mass, and particularly preferably in the range of 0.05 to 2 parts by mass, per 100 parts by mass of polymerizable monomer (A) in the cement.

[0053] (Organic peroxide (D)) The organic peroxide (D) is not particularly limited and any known one can be used. Typical organic peroxides (D) include ketone peroxides, hydroperoxides, diacyl peroxides, dialkyl peroxides, peroxyketals, peroxyesters, and peroxydicarbonates.

[0054] Examples of ketone peroxides include methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, methylcyclohexanone peroxide, and cyclohexanone peroxide.

[0055] Examples of hydroperoxides include 2,5-dimethylhexane-2,5-dihydroperoxide, diisopropylbenzene hydroperoxide, cumene hydroperoxide, and t-butyl hydroperoxide.

[0056] Examples of diacyl peroxides include acetyl peroxide, isobutyryl peroxide, benzoyl peroxide, decanoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, 2,4-dichlorobenzoyl peroxide, and lauroyl peroxide.

[0057] Examples of dialkyl peroxides include di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 1,3-bis(t-butylperoxyisopropyl)benzene, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexine-3.

[0058] Examples of peroxyketals include 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane, and 4,4-bis(t-butylperoxy)valeric acid-n-butyl ester.

[0059] Examples of peroxyesters include α-cumyl peroxyneodecanoate, t-butyl peroxyneodecanoate and t-butyl peroxypivalate, 2,2,4-trimethylpentyl peroxy-2-ethylhexanoate, t-amyl peroxy-2-ethylhexanoate, t-butyl peroxy-2-ethylhexanoate, di-t-butyl peroxyisophthalate, di-t-butyl peroxyhexahydroterephthalate, t-butyl peroxy-3,3,5-trimethylhexanoate, t-butyl peroxyacetate, t-butyl peroxybenzoate and t-butyl peroxymalelic acid.

[0060] Examples of peroxydicarbonates include di-3-methoxyperoxydicarbonate, di-2-ethylhexyl peroxydicarbonate, bis(4-t-butylcyclohexyl)peroxydicarbonate, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, and diallyl peroxydicarbonate.

[0061] Among these, diacyl peroxide is preferred in terms of stability, toxicity, and catalytic activity, and benzoyl peroxide is particularly preferred.

[0062] Furthermore, the amount of organic peroxide (D) is not particularly limited, but from the viewpoint of curability, it is preferably in the range of 0.01 to 5 parts by mass, and particularly preferably in the range of 0.1 to 3 parts by mass, per 100 parts by mass of polymerizable monomer (A).

[0063] (Tertiary aromatic amine composition (E)) In the dental cement composition of the present invention, the blending amount of the tertiary aromatic amine composition (E) containing the above-mentioned components (e1), (e2), and (e3) is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the polymerizable monomer (A) from the viewpoint of curability. In the dental cement composition of the present invention, the blending amount of each of the first to third tertiary aromatic amines (e1) to (e3) may be appropriately determined so as to achieve an optimal cement curing time during irradiation. Specifically, the mass ratio represented by (e1):(e2):(e3) is preferably 1:1 to 5:0.1 to 2, and more preferably 1:2 to 4:0.5 to 1.5. When the amount of the component (e2) is less than 1 part by mass with respect to 1 part by mass of the component (e1), the exciplex formation rate of the component (e1) and the α-diketone compound (C) tends to not be sufficiently delayed. When it exceeds 5 parts by mass, the photopolymerization rate tends to be significantly delayed. Further, when the amount of the component (e3) is less than 0.1 part by mass with respect to 1 part by mass of the component (e1), the photopolymerization activity decreases, and it tends to be difficult to obtain a semi-cured cement that is easy to remove the cement. When it exceeds 2 parts by mass, the photopolymerization activity becomes high, and it tends to be impossible to secure a sufficient cement removal time.

[0064] · Component (e1) The alkyloxycarbonyl group of R3 in the general formula (1) is a group that exhibits an electron-withdrawing property due to resonance effect with respect to the aromatic ring. The alkyloxycarbonyl group has the formula: -CO-OR x (In the formula, R x is an alkyl group.) It is a group represented by. R x The alkyl group in is preferably a linear or branched alkyl group having 1 to 10 carbon atoms, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, tert-butyl, an ethylhexyl group, etc. Preferably, R x is a methyl group or an ethyl group.

[0065] Examples of C1-C6 alkyl groups R1 and R2 in general formula (1) include methyl, ethyl, n-propyl, i-propyl, n-butyl, and n-hexyl groups. Among these, methyl and ethyl groups are preferred.

[0066] In general formula (1), n, which represents the number of R3 (alkyloxycarbonyl group) substitutions on the aromatic ring, is preferably 1. Furthermore, it is preferable that R3 is substituted at the para position due to its high activity.

[0067] (e1)Specific examples of components include 2-ethylhexyl p-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, methyl 4-dimethylaminobenzoate, and methyl 3-(dimethylamino)benzoate. Among these, ethyl 4-dimethylaminobenzoate or methyl 4-dimethylaminobenzoate is preferred because they are easily available or synthesized, and have excellent chemical stability and solubility in polymerizable monomers (A).

[0068] ·(e2) component The C1-C6 alkyl groups R4 and R5 in general formula (2) can preferably be the same as those described for R1 and R2 in general formula (1) above.

[0069] R4 and R5 are preferably alkyl groups having 1 to 6 carbon atoms with substituents. Substituents selected from hydroxyl groups, nitro groups, sulfonic acid groups, and halogen atoms are groups that exhibit electron-withdrawing properties due to inductive effects, and therefore tend to suppress the (ii) hydrogen abstraction reaction of the alkyl group, thus extending the semi-cured state.

[0070] Examples of halogen atoms for the R4 and R5 substituents include chlorine, bromine, fluorine, and iodine atoms. Furthermore, a hydroxyl group is preferred for the substituent from the viewpoint of availability and safety for living organisms.

[0071] Examples of C1-C4 alkyl groups in R6 include methyl, ethyl, n-propyl, i-propyl, and n-butyl groups. Among these, methyl and ethyl groups are preferred.

[0072] The integer representing the number of R6 substitutions on the aromatic ring is preferably 1. R6 substitution at the para position is preferred due to its high activity.

[0073] Examples of such (e2) components include 1,1-[(4-methylphenyl)imino]bis(2-propanol), p-tollidiethanolamine, N,N-di(1-hydroxyethyl)-p-toluidine, N,N-di(2-hydroxypropyl)-p-toluidine, and N,N-di(1-chloroethyl)-p-toluidine. Among these tertiary aromatic amines, it is preferable to use p-tollidiethanolamine or N,N-di(2-hydroxypropyl)-p-toluidine because they are readily available or synthesized, and they exhibit excellent chemical stability and solubility in polymerizable monomers (A).

[0074] ·(e3) component In general formula (3), the substitution of R7 at the para position makes it easier to obtain high activity.

[0075] Specific examples of (e3) components in which R7 is a hydroxyalkyl group include 2-[4-(dimethylamino)phenyl]methanol, 2-[4-(dimethylamino)phenyl]ethanol, 2-[4-(dimethylamino)phenyl]propanol, and 2-[4-(dimethylamino)phenyl]butanol. Among these amine compounds, 4-t-butyl-N,N-dimethylaniline or 2-[4-(dimethylamino)phenyl]ethanol are preferred because they are easily available or synthesized, and they have excellent chemical stability and solubility in polymerizable monomers (A).

[0076] By using the preferred proportions of the above components (e1) to (e3), the excyplex formation rate and photopolymerization rate can be adjusted, and a semi-hardened state suitable for removing excess cement can be maintained.

[0077] (Other ingredients) The dental cement of the present invention may contain known additives, provided that they do not impair its performance. Examples of such additives include polymerization inhibitors, chain transfer agents, antioxidants, pigments, dyes, UV absorbers, and thickeners.

[0078] The dental cement composition of the present invention can be used by blending the above-mentioned components to form a paste. The organic peroxide (D), which is an oxidizing agent and a chemical polymerization initiator, and the tertiary aromatic amine composition (E), which also acts as a reducing agent, react, and the composition is divided into two or more packages for storage to prevent hardening from progressing during storage.

[0079] [Examples] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The compounds used in each example and comparative example, and their abbreviations, are as follows.

[0080] [Regarding the compounds used] (Polymerizable monomer (A)) • 3G: Triethylene glycol dimethacrylate · D-2.6E: 2,2′-Bis(4-(methacryloxyethoxy)phenyl)propane ·Bis-GMA:2,2′-Bis[4-(2-hydroxy-3-methacrylateoxypropoxy)phenyl]propane

[0081] (Filler (B)) Spherical silica-zirconia: γ-methacryloxypropyltrimethoxysilane surface-treated material, average particle size 0.4 μm Amorphous silica-zirconia: γ-methacryloxypropyltrimethoxysilane surface-treated material, average particle size 3 μm Fine silica powder: Average particle size 0.02 μm

[0082] (α-diketone compound (C)) CQ: Camphorquinone

[0083] (Organic peroxide (D)) BPO: Benzoyl peroxide

[0084] (Tertiary aromatic amine composition (E)) (e1) component DMBE: 4-Dimethylaminobenzoate ethyl (Properties: Solid, Molecular weight: 193.24) ·(e2) component DEPT: p-Tolyldiethanolamine (Properties: Solid, Molecular weight: 195.26) ·(e3) component DATB: 4-t-butyl-N,N-dimethylaniline (Properties: Liquid, Molecular weight: 177.29, Boiling point: 250°C~253°C) DABE: 2-[4-(dimethylamino)phenyl]ethanol (Properties: Solid, Molecular weight: 165.23) Tertiary aromatic amines other than components (e1) to (e3) DMPT: N,N-dimethyl-p-toluidine (Properties: Liquid, Molecular weight: 135.21, Boiling point: 211°C) PEAT: N,N-diethyl-p-toluidine (Properties: Liquid, Molecular weight: 163.26, Boiling point: 230°C)

[0085] (Other ingredients) • Chain transfer agent Nofmer: 2,4-diphenyl-4-methyl-1-pentene • Polymerization inhibitors BHT: 2,6-di-t-butyl-4-methylphenol HQME:4-Methoxyphenol

[0086] Dental cement compositions according to Examples 1-4 and Comparative Examples 1-4 were prepared and evaluated as follows.

[0087] [Examples 1-4 and Comparative Examples 1-4] (Example 1) As polymerizable monomer (A), 38 g of 3G, 50 g of D-2.6E, and 12 g of Bis-GMA were used. As tertiary aromatic amine composition (E), 0.8 g of DMBE, 2.5 g of DEPT, and 0.7 g of DATB were used, along with 0.3 g of Nofmer, 0.02 g of BHT, and 0.15 g of HQME. These were stirred until homogeneous. 28 g of the resulting liquid composition was weighed out, and 42 g of amorphous silica-zirconia, 28 g of spherical silica-zirconia, and 2 g of fine silica powder were added and kneaded in a mortar to prepare a first paste with a filler (B) filling rate of 72.1%.

[0088] Similarly, 38 g of 3G, 50 g of D-2.6E, and 12 g of Bis-GMA were used as polymerizable monomers (A), 0.8 g of CQ was used as the α-diketone compound (C), and 3.5 g of BPO was used as the organic peroxide (D). Furthermore, 0.3 g of Nofmer, 0.2 g of BHT, and 0.125 g of HQME were added and stirred until homogeneous. 28 g of the resulting liquid composition was weighed out, and 42.5 g of amorphous silica-zirconia, 28.5 g of spherical silica-zirconia, and 1.0 g of fine silica powder were added and kneaded in a mortar to prepare a second paste with a filler (B) filling rate of 72.1%.

[0089] Equal amounts of the first paste and the second paste, immediately after preparation, were mixed together to prepare a measurement sample. Using this measurement sample from Example 1, (1) a test for the removal of excess cement and (2) a test for measuring the hardening time were performed. Furthermore, after storing the first paste and the second paste in a 40°C incubator for 25 days, a measurement sample was prepared in the same manner, and (1) a test for the removal of excess cement and (2) a test for measuring the hardening time were performed. The evaluation results are shown in Tables 2 and 3.

[0090] (Examples 2-4, Comparative Examples 1-4) The compositions for the first paste and the second paste were prepared in the same manner as in Example 1, except that the types and amounts of chemical polymerization initiators and photopolymerization initiators incorporated into the first and second pastes were changed as shown in Table 1. Next, measurement samples were prepared using these compositions in the same manner as in Example 1, and evaluations were performed in the same manner as in Example 1. The evaluation results are shown in Tables 2 and 3. In Table 1, the numbers in parentheses to the right of the compound abbreviation in each column represent the parts by mass of each component when the polymerizable monomer (A) incorporated into the measurement sample is 100 parts by mass.

[0091] Furthermore, the test methods and evaluation methods for each physical property evaluated in Examples 1-4 and Comparative Examples 1-4 are as follows. Since this composition is a dual-cure type using both a photopolymerization initiator and a chemical polymerization initiator, the operability (photopolymerization) was evaluated by measuring the ease of removal of excess cement, and the operability (chemical polymerization) was evaluated by measuring the curing time. In addition, storage stability was evaluated by checking whether there was any difference in operability between the initial state immediately after preparation of the composition and after storage at 40°C for 25 days.

[0092] (Test methods and evaluation methods) (1) Test method for the removeability of excess cement The cattle were slaughtered, and the incisors were extracted within 24 hours of slaughter. The extracted incisors were polished with P600 waterproof sandpaper under running water until they were parallel and flat to the labial surface, down to a depth of 1 cm. 2 The enamel was partially removed and kept warm in a 37°C constant temperature bath for 2 hours. Equal amounts of the first paste and the second paste were mixed and kneaded for 10 seconds. 30 seconds after the start of kneading, the bovine tooth was removed from the constant temperature bath, and 15 mg of the resulting cement was applied to the enamel surface. A 2 mm square aluminum plate was pressed onto the applied cement, allowing the cement to overflow around the aluminum plate (the overflowing cement is the excess cement), and a test sample was prepared.

[0093] The test samples obtained in this manner were returned to the constant temperature bath, and used to conduct a test on the removeability of excess cement. The irradiation intensity applied to the excess cement was 200 mW / cm². 2The irradiation distance was adjusted accordingly, and light irradiation was performed from directly above using an Ellipa Deep Cure (manufactured by 3M). Light irradiation was started immediately after the excess cement squeezed out when an aluminum plate was pressed onto the applied cement during the preparation of the test samples, and was performed in 1-second increments from 1 second to 10 seconds. For the test samples irradiated for each of the above seconds, an attempt was made to remove the excess cement by immediately inserting a dental probe into the boundary between the excess cement and the aluminum plate and then lifting it. At that time, the degree of removal of the excess cement that adhered to the dental probe and could be removed was classified according to the following criteria.

[0094] A (Good): The probe can be inserted smoothly, and when it is raised, the excess cement adheres to the tip as a large lump, allowing for efficient removal. B (Fairly Good): The excess cement lacks sufficient viscosity; even after inserting and lifting the probe, excess cement adheres to the tip of the probe, but the mass is small / The excess cement is quite hard, and the probe cannot be inserted without considerable force. C (Poor): The excess cement has high fluidity, and even if the probe is inserted and shaken, the excess cement does not adhere as a lump / The excess cement has almost completely hardened, and the probe cannot be inserted.

[0095] (2) Test method for curing time Equal amounts of the first paste and the second paste were mixed and kneaded, and temperature measurement using a thermocouple was started simultaneously. The paste, kneaded for 10 seconds, was filled into a cylindrical mold measuring 6 mm in length and 4 mm in diameter. A thermocouple was attached to one side, and the other side was covered with clear plastic wrap. 30 seconds after the start of kneading, it was placed in a 37°C bead bath (BMB-17) and left to stand until the temperature rise subsided. In the resulting temperature curve, the intersection point of the horizontal line tangent to the highest temperature and the line extending from the temperature rise line was determined, and the time at that point was defined as the curing time.

[0096] (3) Method for evaluating operability Under the above light irradiation conditions, dental cements that received an A rating for the ease of removing excess cement between 2 and 5 seconds after light irradiation, and whose hardening time was within 300 seconds, were evaluated as dental cements that can maintain a semi-hardened state suitable for excess cement and have excellent handling properties.

[0097] (4) Method for evaluating storage stability If, after initial storage and 25 days of storage at 40°C, the ease of removing excess cement was evaluated as A within 2 to 5 seconds of light irradiation, and the difference in hardening time between initial storage and 25 days of storage at 40°C was within 5 seconds, then the storage stability was evaluated as excellent.

[0098] [Table 1]

[0099] [Table 2]

[0100] [Table 3]

[0101] (Evaluation results) Examples 1-4 In Examples 1 and 2, where substituent R7 of the aromatic ring of component (e3) is a t-butyl group, and in Examples 3 and 4, where substituent R7 of the aromatic ring of component (e3) is ethanol, the dental cement compositions showed a removeability rating of A between 2 and 5 seconds, both initially and after long-term storage. The difference in curing time was also within 5 seconds. Thus, it was confirmed that there was almost no change in the removeability of excess cement and curing time between the initial state and after 25 days of storage at 40°C, demonstrating excellent operability and storage stability. Furthermore, comparing Examples 1 and 3, where the mass ratio of component (e3) to component (e1) is less than 1, with Examples 2 and 4, where the mass ratio of component (e3) to component (e1) is 1 or more, it was confirmed that increasing the mass ratio of component (e3) to component (e1) improved the removeability after 1 second of light irradiation from C to B, improving the photopolymerization rate, shortening the curing time by 15 seconds, and improving the chemical polymerization rate. In other words, it was confirmed that by increasing the mass ratio of component (e3) to component (e1), it is possible to adjust the ratio so that it can be removed in a short time.

[0102] • Comparative Example 1 In the dental cement composition according to Comparative Example 1, which did not contain component (e3), it took 6 seconds for the initial removal of excess cement to reach level A, and good operability could not be obtained.

[0103] • Comparative Example 2 In Comparative Example 2, a dental cement composition using DMPT in which substituent R7 of the aromatic ring of component (e3) is a methyl group, the removalability of excess cement after 2 seconds of light irradiation was rated C when stored at 40°C for 25 days. It was also confirmed that longer light irradiation was required for the removalability of excess cement to be rated A. Furthermore, it was confirmed that the hardening time was delayed by nearly 20 seconds when stored at 40°C for 25 days. Thus, it was confirmed that when using DMPT, which has a low molecular weight, is liquid at room temperature, and has a boiling point of 211°C, good handling properties cannot be obtained after long-term storage, and storage stability is not excellent.

[0104] • Comparative Examples 3-4 In Comparative Examples 3 and 4, the dental cement compositions using PEAT, in which the substituent on the N atom of component (e3) is an ethyl group and the substituent R7 of the aromatic ring is a methyl group, similar to Comparative Example 2, when stored at 40°C for 25 days, the removeability of excess cement 2 seconds after the start of light irradiation was C, indicating poor workability. Furthermore, when stored at 40°C for 25 days, the curing time was delayed to over 20 seconds, confirming a slower rate of chemical polymerization. Thus, it was confirmed that good workability and storage stability cannot be obtained when using PEAT, which has a low molecular weight, is liquid at room temperature, and has a boiling point of 230°C. In addition, comparing Comparative Example 3, which contains 0.3 parts by mass of PEAT, with Comparative Example 4, in which the PEAT content was increased to 1.0 part by mass, the curing time was shortened and the rate of chemical polymerization improved in Comparative Example 4, but the removeability after light irradiation was C in both cases, indicating no improvement in the rate of photopolymerization. This is presumed to be because the generated radicals are more stable secondary radicals, and the subsequent addition reaction rate is slower, so no improvement in the rate of photopolymerization beyond a certain point was observed.

Claims

1. It comprises: polymerizable monomer (A): 100 parts by mass, filler (B): 50 parts by mass or more and 500 parts by mass or less, α-diketone compound (C), organic peroxide (D), and tertiary aromatic amine composition (E), The tertiary aromatic amine composition (E) is a dental cement composition comprising a first tertiary aromatic amine (e1) represented by the following general formula (1), a second tertiary aromatic amine (e2) represented by the following general formula (2), and a third tertiary aromatic amine (e3) represented by the following general formula (3). 【Chemistry 1】 (In the formula, R １ and R ２ Each of these is an alkyl group having 1 to 6 carbon atoms, and R ３ (where n is an alkyloxycarbonyl group, and n is an integer from 1 to 3.) 【Chemistry 2】 (In the formula, R ４ and R ５ Each is independently a C1-C6 alkyl group or a C1-C6 alkyl group having substituents selected from a hydroxyl group, a nitro group, a sulfonic acid group, and a halogen atom, and R ４ and R ５ At least one of them is a substituted alkyl group having 1 to 6 carbon atoms having the substituent, R ６ (where m is an alkyl group having 1 to 4 carbon atoms, and m is an integer from 0 to 3.) 【Transformation 3】 (wherein R ７ is a t-butyl group or a hydroxyalkyl group having 1 to 4 carbon atoms).

2. The dental cement composition according to claim 1, comprising: 0.01 parts by mass or more and 5 parts by mass of the α-diketone compound (C); 0.01 parts by mass or more and 5 parts by mass of the organic peroxide (D); and 0.01 parts by mass or more and 10 parts by mass of the tertiary aromatic amine composition (E), wherein the mass ratio of the first, second, and third tertiary aromatic amines, represented by (e1):(e2):(e3), is 1:1 to 5:0.1 to 2.

3. The first tertiary aromatic amine (e1) is ethyl 4-dimethylaminobenzoate or methyl 4-dimethylaminobenzoate, The second tertiary aromatic amine (e2) is p-tolyldiethanolamine or N,N-di(2-hydroxypropyl)-p-toluidine, The dental cement composition according to claim 1 or 2, wherein the third tertiary aromatic amine (e3) is 4-t-butyl-N,N-dimethylaniline or 2-[4-(dimethylamino)phenyl]ethanol.

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