Dental cement and dental cement preparation kits

Abstract

[Problem] To provide dual-cure cement which has a broad light exposure dose range in which a satisfactory semi-cured state can be obtained, such as a state where excess cement can be easily removed can be retained for several minutes, the cement also having a significantly higher strength when formed into a cured article than in the prior art. [Solution] Provided is dental cement characterized by comprising a composition which comprises a polymerizable monomer, a filler, a chemical curing initiator and a photopolymerization initiator, in which a specific tertiary aromatic amine capable of inhibiting photopolymerization, such as N,N-di(1-hydroxyethyl)-p-toluidine, is not substantially contained, the chemical curing initiator contains 0.4 to 1.5 parts by mass of a thiourea compound (c2) having a specific structure such as N-benzoylthiourea, the photopolymerization initiator contains 0.3 to 0.8 part by mass of an α-diketone (d1) and 0.3 to 0.8 part by mass of a photopolymerization accelerator, and the ratio x / y of the content x (part by mass) of the component (d1) to the content y (part by mass) of the component (c2) is 0.3 to 1.9.

Description

[Technical Field]

[0001] This invention relates to dental cement and a kit for preparing dental cement. [Background technology]

[0002] In dental treatment, dual-cure cements are used as luting materials (dental cements) for restorations such as inlays, onlays, laminate veneers, and jacket crowns. These cements can be applied not only to restorations made of light-transmitting materials such as ceramics and composite resins, but also to those made of light-impermeable materials.

[0003] The dual-cure cement described above consists of a highly fluid, paste-like curing composition containing polymerizable monomers, fillers, a chemical polymerization initiator, and a photopolymerization initiator. When using this cement to bond tooth structure to a crown restorative material, an excess amount of dental cement is applied to the restorative material, and the crown restorative material is pressed against the tooth structure. At this time, it is necessary to remove the excess dental cement (also called "excess cement") that has protruded from the joint between the tooth structure and the crown restorative material, called the margin, during the pressing process. From the standpoint of ease of handling, this removal of excess cement is usually done by scraping it off with a dental needle or similar tool when the excess cement is semi-hardened (a state in which hardening has progressed and fluidity has been reduced to some extent). However, since the removal of excess cement in the oral cavity is a delicate and nerve-wracking task, it may take several minutes, and it is desirable to maintain a semi-hardened state during the work.

[0004] When using dual-cure cement, it is possible to wait until the excess cement reaches the semi-hardened state due to chemical polymerization without light irradiation before starting the removal process. However, from the perspective of saving time, it is common to irradiate the cement with an appropriate amount of light after the pressure welding to bring it to a semi-hardened state. The following are known dual-cure cements that allow for easy removal of excess cement in this semi-hardened state.

[0005] Specifically, Patent Document 1 discloses a dual-cure type cement comprising (a) a polymerizable monomer, (b) an α-diketone compound, (c) a composition consisting of a combination of three types of tertiary aromatic amines i) to iii) each having a specific structure, (d) a filler, and (e) a peroxide. Here, the three types of tertiary aromatic amines constituting (c) all function as co-catalysts for α-diketones, and one of them, i), has the function of promoting photopolymerization, while the other two, ii) and iii), have the function of preventing the time during which the semi-cured state can be maintained from being shortened by the use of i). Furthermore, according to Patent Document 1, the excess cement generated by pressing the dual-cure type cement is irradiated with an irradiation intensity of 380 to 420 mW / cm². 2 By irradiating the material with light at a distance of approximately 1 cm for 2 to 4 seconds, it reaches a semi-hardened state (suitable for removal work), and this state can be maintained for more than 2 minutes (corresponding to the time until the effects of chemical polymerization hardening begin to appear).

[0006] Furthermore, Patent Document 2 discloses a dental adhesive material kit that is excellent in removeability when excess cement is removed in a semi-hardened state by pre-irradiating with a light curing device, and has appropriate strength, comprising a dental water-based adhesive composition (A) and a dental hardening composition (B), wherein the difference between the polymerization start time of (B): t2 (min) and the polymerization start time of (A) and (B) at contact: t1 (min), (t2-t1), is 3 (min) or less. According to Patent Document 2, (A) refers to a surface treatment agent (primer) for the tooth surface, and (B), when used in a dental cement kit, refers to a resin cement that bonds the tooth structure to the prosthesis. Furthermore, it has been reported that when pressure bonding was performed using the above-mentioned (A), which includes a radical polymerizable monomer containing an acidic group (a), a radical polymerizable monomer not containing an amino group or an acidic group (b-1), a polymerization accelerator (c), and water (d), and (B), which includes a radical polymerizable monomer not containing an acidic group (b), a polymerization accelerator (c), a chemical polymerization initiator (f), a photopolymerization initiator (g), and a filler (h), and the excess cement after 1 minute was irradiated with light from a dental LED light curing unit in standard mode for 10 seconds per rotation, the excess cement could be easily removed in one piece. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 5773676 [Patent Document 2] International Publication No. 2020 / 111142 [Overview of the project] [Problems that the invention aims to solve]

[0008] When excess cement is irradiated with light to a semi-hardened state, the fluidity and other properties of the excess cement after irradiation depend on the light irradiation conditions, and it is necessary to control the light irradiation conditions to make it suitable for removal. The conditions used in Patent Document 1 were investigated in a simulated test using bovine teeth and serve as a guideline, but in actual treatment, it may be difficult to bring the irradiation window of the light curing unit close to the excess cement, and the light irradiation may be performed at a lower intensity. In addition, the irradiation time (the time actually irradiated to the area that needs irradiation) may be shortened due to vibrations, etc. In such cases, it may not be possible to achieve the desired semi-hardened state. For example, the inventors used an LED light curing unit at 300 mW / cm² for the cement in Patent Document 1. 2 When light irradiation was performed and the ability to remove excess cement was evaluated, it was found that under the condition of light irradiation for 1 second, a semi-hardened state was not reached, and it was difficult to remove the excess cement in one lump (see Comparative Example 9 below).

[0009] Furthermore, in the case of dental cement, from the viewpoint of adhesive durability, it is desirable that the dental cement present at the joint hardens completely to become a high-strength hardened body. In other words, if the strength of the hardened cement is low, the restoration is more likely to fall off. The flexural strength of the hardened bodies of conventional dual-cure type cements, such as those disclosed in Patent Documents 1 and 2, is approximately 100 to 130 MPa, and there is room for improvement.

[0010] Therefore, the present invention aims to provide a dual-cure type cement that, when light irradiation is applied to excess cement generated after pressure welding to achieve a semi-hardened state, has a wide range of light irradiation doses (product of irradiation time and irradiation intensity) that can maintain a state where the excess cement can be easily removed for several minutes, and allows for the removal of excess cement with good operability even with a small irradiation dose, and further provides a dual-cure type cement in which the strength of the hardened body is significantly higher than that of conventional cements. [Means for solving the problem]

[0011] The present invention solves the above problems, and the dental cement according to the first aspect of the present invention (hereinafter, also referred to as "the dental cement of the present invention") is composed of a composition containing a polymerizable monomer (A), a filler (B), a chemical polymerization initiator (C), and a photoinitiator (D). The blending amount of the filler (B) is 50 to 500 parts by mass with respect to 100 parts by weight of the polymerizable monomer (A). The dental cement of the present invention substantially does not contain a tertiary aromatic amine represented by the following general formula (1). The chemical polymerization initiator (C) contains a hydroperoxide (c1): 0.2 to 3.5 parts by mass and a thiourea compound (c2) represented by the following general formula (2): 0.4 to 1.5 parts by mass. The photoinitiator (D) contains an α-diketone (d1): 0.3 to 0.8 parts by mass and a photoinitiator accelerator (d2): 0.3 to 0.8 parts by mass. The ratio of the content (parts by mass) of the α-diketone (d1) to the content (parts by mass) of the thiourea compound (c2) is 0.3 to 1.9. [Chemical formula] (In the formula, R a and R b may be different from each other and are an alkyl group having 1 to 6 carbon atoms, or a substituted alkyl group having 1 to 6 carbon atoms having a hydroxyl group, a nitro group, a sulfone group, or a halogen atom as a substituent. R a and R b at least one of which is the above substituted alkyl group, and R c is an alkyl group having 1 to 4 carbon atoms, and m is an integer of 0 to 3.) [Chemical formula] (In the formula, R 1 , R 2 and R 3 are each a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heterocyclic group, an acyl group, an aralkyl group, or an alkenyl group, and R 1 and R 2 may be bonded to each other to form a ring.)

[0012] A second embodiment of the present invention is a dental cement preparation kit (hereinafter also referred to as "the kit of the present invention") comprising a first agent and a second agent, which are packaged separately from each other, and for preparing the dental cement of the above embodiment by mixing the two agents. The first agent contains the thiourea compound (c2) and the α-diketone (d1). The second agent contains the hydroperoxide (c1). [Effects of the Invention]

[0013] The dental cement of the present invention is a dual-cure type cement that has a wide range of light irradiation doses that allows it to maintain a good semi-cured state for several minutes, making it easy to remove excess cement. Furthermore, even if the irradiation time is shortened or the irradiation intensity is weakened, it is not only easy to remove excess cement, but it also has the excellent feature of having high hardened strength. [Modes for carrying out the invention]

[0014] 1. Outline of the present invention As described above, the dual-cure cement disclosed in Patent Document 1 exhibits reduced removeability of excess cement when the amount of light irradiation is low. The inventors considered that the cause of this might be that "tertiary aromatic amine ii)", one of the three tertiary aromatic amines constituting the tertiary aromatic amine composition in (c) above, specifically "tertiary aromatic amine", in which one "phenyl group in which 1 to 3 hydrogen atoms may be substituted with an alkyl group having 1 to 4 carbon atoms" and two "substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms" are bonded to a nitrogen atom, and at least one of the two "substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms" has a hydroxyl group, nitro group, sulfone group, or halogen atom as a substituent, reduced the activity of the photopolymerization initiator. Therefore, the inventors investigated a system that does not contain the above "tertiary aromatic amine ii)". Specifically, Patent Document 1 states that when the above-mentioned "tertiary aromatic amine ii)" is not included (Comparative Example 2), the photocuring speed is fast, and complete curing occurs in 3 seconds of light irradiation. Therefore, we investigated a system in which the amount of α-diketone (d1) added (in the above comparative example, 2 parts by mass of α-diketone were used per 100 parts by mass of polymerizable monomer) was reduced.

[0015] As a result, although the desired semi-cured state can sometimes be obtained with a small amount of light irradiation in this system, the strength of the cured product obtained by photopolymerization alone actually decreases, and even with the compensatory effect of chemical polymerization, the final cured product strength obtained was at the same level as conventional methods.

[0016] Therefore, with the aim of increasing the strength of the cured product without reducing the activity of the photopolymerization initiator (D), further investigations were conducted. It was found that when a specific thiourea compound (c2) is incorporated as a so-called polymerization accelerator that functions as a reducing agent for hydroperoxide (c1), a good semi-cured state can be obtained in a range of light irradiation from low to relatively wide, even when the amount of α-diketone (d1) is increased (to an amount that ultimately causes sufficient photocuring). Furthermore, it was found that the final strength of the cured product is improved when the ratio of the amount of the specific thiourea compound (c2) to the amount of α-diketone (d1) is set within a specific range, thus completing the present invention.

[0017] Although this invention is not bound by any theory, the reason why the aforementioned effects are obtained in the dental cement of this invention is thought to be as follows. That is, when a specific thiourea compound (c2) and α-diketone (d1) are blended in a specific ratio, the thiourea compound (c2) also acts as a chain transfer agent, so even if the amount of photopolymerization initiator (D) is increased, the range of light irradiation doses at which a semi-cured state can be obtained does not narrow. Furthermore, regarding the improvement in the strength of the hardened cement, it is known that when complete hardening occurs, the photopolymerized hardened material is stronger than the chemically polymerized hardened material (at room temperature), so it is thought that this is because it became possible to use an amount of photopolymerization initiator (D) that causes complete photocuring.

[0018] The dental cement and dental cement preparation kit of the present invention will be described in detail below. In this specification, unless otherwise specified, the notation "x~y" using numerical values ​​x and y means "more than or equal to x and less than or equal to y". If a unit is attached only to the numerical value y in such notation, that unit shall also apply to the numerical value x. 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".

[0019] 2. Details of dental cement (1) Overall structure The dental cement of the present invention is a dual-cure type cement and is a composition comprising a polymerizable monomer (A), a filler (B), a chemical polymerization initiator (C), and a photopolymerization initiator (D), wherein the amount of filler (B) is 50 to 500 parts by mass per 100 parts by weight of the polymerizable monomer (A). A key feature of the dental cement of the present invention is that specific chemical polymerization initiators (C) and photopolymerization initiators (D) are used in specific amounts, and specific tertiary aromatic amines that reduce the activity of the photopolymerization initiator (D) are not used.

[0020] In other words, the composition constituting the dental cement of the present invention must satisfy the following conditions [1] to [4].

[0021] [1] Substantially free of tertiary aromatic amines represented by the following general formula (1) (hereinafter also referred to as "non-aromatic amines"). [ka] Note that R in equation (1) above a and R b Each is independently a C1-C6 alkyl group, or a C1-C6 substituted alkyl group having a hydroxyl group, nitro group, sulfone group, or halogen atom as a substituent, and R a and R b At least one of them is a substituted alkyl group, R c m is an alkyl group having 1 to 4 carbon atoms, and m is an integer from 0 to 3.

[0022] Here, "substantially absent" means either completely absent or present in an amount that does not affect the polymerization activity of the photopolymerization initiator (D). Content of non-contained aromatic amines: N AM (mol) and α-diketone (d1) content: N d1 (mol) Mole ratio N AM / N d1 This means that the value is in the range of 0 to 1 / 500, preferably in the range of 0 to 1 / 1000.

[0023] [2] As a chemical polymerization initiator (C), a solution containing hydroperoxide (c1): 0.2 to 3.5 parts by mass and a thiourea compound (c2) represented by the following general formula (2): 0.4 to 1.5 parts by mass is used. [ka] Note that R in equation (2) above 1 , R 2 and R 3 Each of these is independently a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heterocyclic group, an acyl group, an aralkyl group, or an alkenyl group, and R 1 and R 2 These elements may be joined to each other to form a ring.

[0024] [3] As the photopolymerization initiator (D), a solution containing α-diketone (d1): 0.3 to 0.8 parts by mass and a photopolymerization accelerator (d2): 0.3 to 0.8 parts by mass is used.

[0025] [4] The ratio x / y of the content x (parts by mass) of the α-diketone (d1) to the content y (parts by mass) of the thiourea compound (c2) is 0.3 to 1.9.

[0026] If these conditions are not met, the effects of the present invention cannot be obtained. For example, if condition [1] is not met, the removeability of excess cement decreases if the amount of light irradiation is low. Also, if condition [2] is not met, in particular the amount of thiourea compound (c2) added falls below the lower limit of the range, the range of light irradiation amounts in which photocuring progresses with very short light irradiation and a good semi-cured state can be obtained becomes extremely narrow. On the other hand, if the amount of thiourea compound (c2) added exceeds the upper limit, curing becomes insufficient when the light irradiation intensity is weak and the irradiation time is short, and the removeability of excess cement decreases. Also, if the amount of α-diketone (d1) added in condition [3] falls below the lower limit of the range, high cured body strength cannot be obtained, and if it exceeds the upper limit, the range of light irradiation amounts in which a good semi-cured state can be obtained becomes narrow, similar to the above. Furthermore, if the above condition [4] is not satisfied and x / y is below the lower limit, the range of light irradiation doses in which photocuring progresses with a very short time and a good semi-cured state can be obtained becomes extremely narrow, and if it exceeds the upper limit, curing becomes insufficient when the light irradiation dose is low, and the ability to remove excess cement decreases.

[0027] Aside from the above-mentioned features, the dental cement of the present invention is fundamentally no different from conventional dual-cure type cements. The polymerizable monomer (A) and filler (B) can be those that are usable in conventional dual-cure type cements without any particular restrictions, and the amount of filler (B) is within the range of general formulations. Furthermore, the hydroperoxide (c1), α-diketone (d1), and photopolymerization accelerator can also be those that are usable in conventional dual-cure type cements without any particular restrictions.Therefore, first, the non-containing aromatic amines that are substantially not included in the dental cement of the present invention under the above condition [1] will be explained, and then the details of each component used in the dental cement of the present invention will be explained below.

[0028] (2) Details of each ingredient (a) Non-contained aromatic amines The non-contained aromatic amine is a compound represented by the general formula (1) above, and corresponds to the tertiary aromatic amine ii) used in the dual-cure dental cement disclosed in Patent Document 1. The non-contained aromatic amine is thought to have the function of reducing the activity of the photopolymerization initiator, and if this component is included, the effects of the present invention will be difficult to obtain. For this reason, the dental cement of the present invention is substantially free of non-contained aromatic amines. That is, the content of non-contained aromatic amines contained in the dental cement of the present invention: N AM (mol) represents the content of component (d1): N d1 (mol) Mole ratio N AM / N d1 Expressed as such, the ratio should be 1 / 500 or less, preferably 1 / 1000 or less, and most preferably 0 (containing no non-contained aromatic amines at all).

[0029] Specific examples of non-contained aromatic amines include 2,2-[3-(methylphenyl)imino]bisethanol acetate, 1,1-[(4-methylphenyl)imino]bis(2-propanol), N,N-di(1-hydroxyethyl)-p-toluidine, N,N-bis(2,2,2-trifluoroethyl)-p-toluidine, N,N-di(1-hydroxyethyl)-p-toluidine, N,N-di(2-hydroxypropyl)-p-toluidine, N-(1-cyanoethyl)-N-(1-acetoxyethyl)-m-toluidine, and N,N-di(1-chloroethyl)-p-toluidine.

[0030] Although non-contained aromatic amines are sometimes used as reducing agents in redox-type chemical polymerization initiators, in order to satisfy the above condition [1], the chemical polymerization initiator (C) used in the dental cement of the present invention does not contain a non-contained aromatic amine as a reducing agent.

[0031] (b) Polymerizable monomer (A) In the present invention, polymerizable monomer (A) (hereinafter also simply referred to as "component (A)") can be any polymerizable monomer that is said to be usable in dental cement without particular limitations, but it is preferable to use a radical polymerizable monomer. Examples of radical polymerizable unsaturated groups possessed by radical polymerizable monomers include (meth)acryloyl groups such as (meth)acryloyl group, (meth)acryloyloxy group, (meth)acryloylamino group, and (meth)acryloylthio group, as well as vinyl group, allyl group, and styryl group.

[0032] From the viewpoint of polymerizability and biosafety, radical polymerizable groups preferably consist of (meth)acrylic acid ester-based radical polymerizable monomers. Specifically, monofunctional polymerizable monomers such as ethylhexyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, or glycidyl (meth)acrylate, as well as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, and 2,2-bis[4-(3-methacryloyloxy) Examples include difunctional polymerizable monomers such as -2-hydroxypropoxyphenyl]propane, 2,2'-bis(4-methacryloxypolyethoxyphenyl)propane, and 1,6-bisethyloxycarbonylamino)trimethylhexane; trifunctional polymerizable monomers such as trimethylolpropane tri(meth)acrylate and pentaerythritol tri(meth)acrylate; and tetrafunctional polymerizable monomers such as pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and pentaerythritol hexa(meth)acrylate.

[0033] Furthermore, among the above-mentioned polymerizable monomers that do not contain acidic groups, it is preferable to include polymerizable monomers with two or more functionalities from the viewpoint of mechanical strength.

[0034] In the present invention, the polymerizable monomer (A) 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.

[0035] (c) Filler (B) The filler (B) of the present invention (hereinafter also simply referred to as "component (B)") is blended in an amount of 50 to 500 parts by mass, preferably 150 to 400 parts by mass, per 100 parts by mass of polymerizable monomer, for the purpose of improving the strength of the cement, suppressing shrinkage during polymerization, and adjusting the viscosity (workability) of the cement before it hardens. 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 blended in an amount exceeding 500 parts by mass, the viscosity will increase, resulting in poor workability such as a heavy mixing feel, or the cement may become too thick, resulting in poor fit with the prosthesis.

[0036] As filler (B), one or more types selected from inorganic fillers, organic fillers, and inorganic-organic composite fillers can be used as appropriate.

[0037] 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.

[0038] 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, ytterbium fluoride, calcium carbonate, aluminum silicate, and fluoroaluminosilicate glass. Two or more of these can also be used in combination.

[0039] In addition, inorganic-organic composite fillers can also be suitably used. The composite method is not particularly limited, and the composite may be solid or have pores. From the viewpoint of the mechanical strength of the cured product, it is preferable to use an organic-inorganic composite filler in which the surface of inorganic aggregated particles is coated with an organic polymer and has pores, as described in International Publication No. 2013 / 039169.

[0040] The inorganic fillers or inorganic-organic composite fillers described above can be treated with surface treatment agents, such as silane coupling agents, to improve their affinity for polymerizable monomers, dispersibility into polymerizable monomers, mechanical strength of the cured product, and water resistance. Such surface treatment agents are not limited in any way, and the surface treatment methods using them can also be in accordance with known methods.

[0041] 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.

[0042] (d) Chemical polymerization initiator (C) The dental cement of the present invention uses a chemical polymerization initiator (C) containing hydroperoxide (c1) (hereinafter also simply referred to as "component (c1)") and a specific thiourea compound (c2) represented by the general formula (2) (hereinafter also simply referred to as "component (c2)"). Component (c1) functions as an oxidizing agent, and component (c2) functions as a reducing agent. The dental cement of the present invention hardens by generating radicals through the reaction of these two agents. As stated above, the chemical polymerization initiator (C) used in the dental cement of the present invention may contain other chemical polymerization initiators to the extent that they do not hinder the effects of the present invention, but it does not contain any non-contained aromatic amines that function as reducing agents as optional components. Components (c1) and (c2) will be described in detail below.

[0043] ·(c1) component (c1) Any hydroperoxide compound that functions as an oxidizing agent can be used without particular limitation as component (c1). Specific examples of hydroperoxide compounds that can be suitably used include 1,1,3,3-tetramethylbutyl hydroperoxide, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide, and t-amyl hydroperoxide. Among these, 1,1,3,3-tetramethylbutyl hydroperoxide and cumene hydroperoxide can be suitably used from the viewpoint of safety, reactivity, and storage stability.

[0044] The content of component (c1) in the dental cement of the present invention is 0.2 to 3.5 parts by mass, preferably 0.25 to 3 parts by mass, per 100 parts by mass of component (A), from the viewpoint of chemical polymerization reaction rate and storage stability. If it is less than 0.2 parts by mass, radical generation by chemical reaction will be insufficient, resulting in poor hardening or a decrease in the strength of the hardened body after final hardening. If it exceeds 3.5 parts by mass, the mechanical strength of the hardened body after final hardening will decrease due to the relative decrease in the content of component (A). In addition, the generation of radicals due to the decomposition of component (c1) makes the cement more prone to gelation, and the storage stability will decrease.

[0045] ·(c2) component Component (c2) functions as a reducing agent, and the dental cement of the present invention hardens by generating radicals in reaction with component (c1). On the other hand, it also acts as a chain transfer agent, and is presumed to suppress the polymerization reaction rate during light irradiation. As a result, it is presumed that by adding an appropriate amount of component (c2), even when a large amount of photopolymerization initiator is added, the light irradiation time required to obtain the semi-hardened state when removing excess cement during photopolymerization will not be shortened.

[0046] (c2) The component is not particularly limited as long as it is a compound represented by the general formula (2), but R in the general formula (2) is not particularly limited. 1 and R 2 Both are hydrogen atoms, R 3 It is preferable that the compound is an alkyl group, pyridyl group, or aryl group having 1 to 3 carbon atoms. Examples of such specific thiourea compounds include N-acetylthiourea, 2-pyridylthiourea, and N-benzoylthiourea. From the viewpoint of reactivity as a chemical polymerization initiator and storage stability, 2-pyridylthiourea and N-benzoylthiourea are particularly preferred. Component (c2) may be used alone, or two or more may be used in combination as needed.

[0047] The content of component (c2) in the dental cement of the present invention is 0.4 to 1.5 parts by mass, preferably 0.5 to 1.2 parts by mass, per 100 parts by mass of component (A), from the viewpoint of chemical polymerization reaction rate and storage stability. If the content is less than 0.4 parts by mass, the effect of component (c2) as a chain transfer agent is not sufficiently obtained, so the photocuring rate becomes too high, shortening the light irradiation time required to obtain a semi-cured state when removing excess cement. In addition, radical generation by chemical reaction becomes insufficient, leading to poor curing or a decrease in the strength of the cured body under chemical curing conditions. On the other hand, if the content exceeds 1.5 parts by mass, the effect of component (c2) as a chain transfer agent becomes excessive, resulting in insufficient curing when the light irradiation intensity is low and the irradiation time is short, and the ability to remove excess cement decreases. In addition, if the chemical curing rate becomes too high, there is not enough time to manipulate the dental cement.

[0048] (e) Photopolymerization initiator (D) The dental cement of the present invention uses a photopolymerization initiator (D) containing α-diketone (d1) (hereinafter also simply referred to as "component (d1)") and a photopolymerization accelerator (d2) (hereinafter also simply referred to as "component (d2)"). These components are described below.

[0049] (d1) component The (d1) component can be any α-diketone that functions as a photopolymerization initiator without particular limitations. Examples of α-diketones that can be preferably used include benzyl, camphorquinone, p,p'-dimethoxybenzyl, p,p'-dictrenequinone, 3,4-phenanthrenequinone, and 9,10-phenanthrenequinone. These α-diketones (d1) can be used alone or in combination of two or more types. From the viewpoint of storage stability and activity as a photopolymerization initiator, camphorquinone is particularly preferred.

[0050] The content of component (d1) in the dental cement of the present invention is 0.3 to 0.8 parts by mass, preferably 0.4 to 0.6 parts by mass, per 100 parts by mass of component (A), from the viewpoint of the ease of removing excess cement during light curing and the strength of the cured body during light curing. If it is less than 0.3 parts by mass, the strength of the dental cement cured by light irradiation will be insufficient. On the other hand, if it exceeds 0.8 parts by mass, the polymerization rate during light irradiation will be too high, shortening the range of light irradiation time in which good excess cement removal can be obtained, and resulting in poor excess cement removal.

[0051] In the dental cement of the present invention, in order to obtain good excess cement removal properties through light curing, the ratio of the content of component (c2) to component (d1) must be within a specific range. Specifically, when the content of component (c2) is y parts by mass and the content of component (d1) is x parts by mass, x / y = 0.3 to 1.9, preferably 0.33 to 1.5. If x / y is less than 0.3, the ratio of component (c2) to component (d1) is too high, and the cement does not reach a semi-cured state at low irradiation intensity and short light irradiation time, resulting in poor excess cement removal properties. On the other hand, if x / y exceeds 1.9, the effect of component (c2) as a chain transfer agent is not sufficiently obtained, and the range of light irradiation time in which good excess cement removal properties can be obtained becomes shorter.

[0052] ·(d2) component Component (d2) is a component that promotes radical generation when used in combination with component (d1). In the dental cement of the present invention, it is preferable to use tertiary amines (excluding non-aromatic amines). In particular, from the viewpoint of reactivity and storage stability, it is more preferable to use compounds in which a nitrogen atom is directly substituted on the aromatic group. Examples of photopolymerization accelerators include N,N-dimethylaniline, N,N-diethylaniline, N,N-di-n-butylaniline, N,N-dibenzylaniline, N,N-dimethyl-p-toluidine, N,N-dimethyl-m-toluidine, N,N-diethyl-p-toluidine, p-bromo-N,N-dimethylaniline, m-chloroN,N-dimethylaniline, p-dimethylaminobenzaldehyde, p-dimethylaminoacetophenone, p-dimethylaminobenzoic acid ethyl ester, p-dimethylaminobenzoic acid amino ester, N,N-dimethylanthranic acid methyl ester, p-dimethylaminostyrene, N,N-dimethyl-3,5-xylidine, 4-dimethylaminopyridine, N,N-dimethyl-α-naphthylamine, and N,N-dimethyl-β-naphthylamine. These photopolymerization accelerators can be used individually or in combination of different types. Among these, p-dimethylaminobenzoic acid ethyl ester is preferably used.

[0053] Furthermore, while some of these tertiary amines function as reducing agents for chemical polymerization initiators, even when such tertiary amines are used, they function as photopolymerization accelerators when the dental cement of the present invention is irradiated with light immediately after preparation.

[0054] The content of component (d2) in the dental cement of the present invention is 0.3 to 0.8 parts by mass, preferably 0.4 to 0.6 parts by mass, per 100 parts by mass of component (A), from the viewpoint of the ease of removing excess cement during light curing and the strength of the cured body during light curing. If it is less than 0.3 parts by mass, the strength of the dental cement cured by light irradiation will be insufficient. On the other hand, if it exceeds 0.8 parts by mass, the polymerization rate during light irradiation will be too high, shortening the range of light irradiation time in which good excess cement removal can be obtained, and resulting in poor excess cement removal.

[0055] (f) Other components The dental cement of the present invention may contain additives as optional components, provided that they do not impair its performance. Examples of such additives include polymerization inhibitors such as dibutylhydroxytoluene and hydroquinone monomethyl ether, chain transfer agents, antioxidants, pigments, dyes, ultraviolet absorbers, and thickeners.

[0056] 3. Details of the dental cement preparation kit The dental cement preparation kit of the present invention consists of a first agent and a second agent, which are packaged separately from each other, and is a kit for preparing the dental cement described in claim 1 by mixing the two agents.

[0057] Specifically, the kit of the present invention having the above characteristics consists of a combination of a first component (component 1) and a second component (component 2), which are packaged in a manner that prevents physical contact between them. The dental cement of the present invention is prepared by mixing both components (both component compositions) at the time of use. In the dental cement of the present invention, chemical polymerization is initiated by the coexistence of component (c1) and component (c2). Therefore, in the kit of the present invention, component (c1) and component (c2) must be packaged separately to ensure stable storage. Furthermore, component (d1) may decompose when coexisting with component (c1), so from the viewpoint of storage stability, it is incorporated into the agent containing component (c2). For this reason, component 1 contains component (c2) and component (d1), and component 2 contains component (c1). Component 1 and component 2 are packaged separately to prevent these components from reacting before use. In addition, polymerizable monomer (A) is included in both component 1 and component 2. Furthermore, the photopolymerization accelerator (d2) and filler (B) may be incorporated into either the first or second component.

[0058] In other words, if the agent containing the thiourea compound (c2) is considered as agent 1, then agent 1 contains a portion of the polymerizable monomer (A), the thiourea compound (c2), and the α-diketone (d1), but does not contain the hydroperoxide (c1); agent 2 contains the remainder of the polymerizable monomer (A) and the hydroperoxide (c1), but does not contain the thiourea compound (c2) or the α-diketone (d1); and the filler (B) and the photopolymerization accelerator (d2) are each included in either agent 1 or agent 2, or are divided and included in both agent 1 and agent 2.

[0059] However, since component (d2) may decompose, though not to the same extent as component (d1), when coexisting with component (c1), it is preferable to include it in a preparation containing component (c2) from the viewpoint of storage stability, and it is preferable to adopt the following packaging method. Component 1: (A) part of component, (B) part of component, (c2) component, (d1) component, (d2) component Two components: (A) the remainder of component (B), and (c1) component.

[0060] Furthermore, "packaged in a state where physical contact is impossible" means a state in which agent 1 and agent 2 are separated and packaged by an inhibitory member (packaging member) that inhibits molecular diffusion between them. Generally, resins suitable for use as container or bag materials are used as the inhibitory member (packaging member). A typical example of a "state where physical contact is impossible" is a state in which one type of composition is stored in a sealed state in a container that blocks outside air and external light. Specific packaging forms include being filled into containers such as bottles, tubes, and syringes. Methods for preparing the dental cement of the present invention using the kit of the present invention include, for example, i) applying appropriate amounts of agent 1 and agent 2 onto mixing paper and mixing them together with a spatula; ii) when agent 1 and agent 2 are in paste form, simultaneously extruding agent 1 and agent 2 from a syringe with a mixing tip attached to the end; and iii) when agent 1 and agent 2 are in liquid form, collecting agent 1 and agent 2 in the same mixing dish.

[0061] The composition of component 1 and component 2 is basically determined so that when the two components are mixed in equal amounts, that is, when the mixing ratio of component 1 to component 2 (amount of component 1 / amount of component 2) is 1 / 1, or when the mixing ratio of component 1 to component 2 (100 × amount of component 1 / amount of component 2) is 100%, the composition of the dental cement of the present invention is obtained. Then, component 1 and component 2 can be easily prepared by weighing and mixing each component according to the composition determined in this way. Note that the above "equal amounts" usually means equal amounts by mass, but when the composition is liquid, it may be equal amounts by volume.

[0062] However, in actual use, that is, when mixing the first and second components to prepare the dental cement of the present invention, it may not be possible to strictly maintain the mixing ratio at 1 / 1. In this case, it is preferable to ensure that the dental cement of the present invention having the desired composition can be obtained when mixed at a mixing ratio other than 1 / 1 (hereinafter also referred to as the "specified mixing ratio"). The specified mixing ratio (this value expressed as a percentage is also referred to as the "specified mixing ratio") can be appropriately determined within a range that does not significantly impair polymerization activity and handling properties. However, from practical viewpoints such as ease of handling and ease of product packaging, it is preferable that the specified mixing ratio (rate) be within the range of 1 / 5 to 5 / 1 (mixing ratio: 20% to 500%), and more preferably within the range of 1 / 3 to 3 / 1 (mixing ratio: 33% to 300%), based on mass (or volume).

[0063] The specified mixing ratio (rate) can be displayed on a medium for displaying mixing ratio (rate) information. Examples of such mediums for displaying mixing ratio (rate) information include: i) product packaging consisting of a cardboard box, etc.; ii) product instruction manuals provided in paper and / or electronic format; iii) containers (bottles, syringes, packaging bags, etc.) for storing the first and second components in a sealed state; iv) product catalogs provided in paper and / or electronic format; and v) communications sent to product users separately from the product via email or postal mail. The specified mixing ratio may also be provided to product users in a manner that allows them to recognize it, other than those shown in i) to v) above.

[0064] When using the kit of the present invention, the mixed composition (dental cement of the present invention) obtained by mixing the first partial composition (component 1) and the second partial composition (component 2) contains all types of chemical polymerization initiators (C) and polymerizable monomers (A), and therefore polymerizes and hardens quickly or within a predetermined operating time. This allows for the production of a hardened body. Known methods can be used to polymerize and harden the mixed composition. For example, the mixed composition can be applied to the area requiring hardening and left to stand. In this case, the mixed composition can be sufficiently hardened by maintaining the applied mixed composition at a temperature range of 10 to 37°C. [Examples]

[0065] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0066] 1. First, the components of each example and comparative example, and the abbreviations of the substances used in the compositions containing them, are described below.

[0067] <Polymerizable monomer (A)> Bis-GMA; 2,2-Bis[4-(3-methacryloyloxy)-2-hydroxypropoxyphenyl]propane 3G; Triethylene glycol dimethacrylate D-2.6E; 2,2'-bis(4-methacryloxypolyethoxyphenyl)propane.

[0068] <Filler (B)> F1; Silica-zirconia filler with an average particle size of 3 μm. F2; Silica-zirconia filler with an average particle size of 0.2 μm.

[0069] <Chemical polymerization initiator (C)> • Hydroperoxide (C1) PO1; 1,1,3,3-tetramethylbutyl hydroperoxide PO2; Cumene Hydroperoxide • Specific thiourea compounds (c2) BzTU;N-benzoylthiourea PyTU; 2-pyridylthiourea.

[0070] <Chemical polymerization initiators other than component (c1) and component (c2)> BPO; Benzoyl peroxide DMPT; N,N-dimethylparatoluidine DEPT; N,N-di(1-hydroxyethyl)-p-toluidine (a non-contained aromatic amine).

[0071] <Photopolymerization initiator (D)> • α-diketone (d1) CQ; Camphor Quinone • Photopolymerization accelerator (d2) DMBE; p-dimethylaminobenzoic acid ethyl ester.

[0072] <Other> BHT; Dibutylhydroxytoluene.

[0073] 2. Next, dental cements relating to Examples 1-15 and Comparative Examples 1-10 were prepared and evaluated using the following methods.

[0074] Example 1 To prepare a component 1 consisting of the first partial composition, 50 parts by mass of a polymerizable monomer (A) consisting of 6 parts by mass of BisGMA, 19 parts by mass of 3G, and 25 parts by mass of D-2.6E was dissolved with 1 part by mass of PyTU, 0.5 parts by mass of CQ, 0.5 parts by mass of DMBE, and 0.15 parts by mass of BHT, and then 143 parts by mass of filler (B) consisting of 57 parts by mass of F1 and 86 parts by mass of F2 was mixed in. To prepare a component 2 consisting of the second partial composition, 50 parts by mass of a polymerizable monomer (A) consisting of 6 parts by mass of BisGMA, 19 parts by mass of 3G, and 25 parts by mass of D-2.6E was dissolved with 2.5 parts by mass of PO1 and 0.3 parts by mass of BHT, and then 143 parts by mass of filler (B) consisting of 57 parts by mass of F1 and 86 parts by mass of F2 was mixed in.

[0075] The two components prepared in this manner were mixed in equal amounts to prepare dental cement, and the excess cement removeability and hardened body flexural strength were evaluated using the methods described below. As a result, the excess cement removeability was as follows: 2 In this case, the irradiation time is 1-3 seconds and the value is A, with an irradiation intensity of 1200 mW / cm². 2 In this case, the result was A after irradiation time of 3-4 seconds and B after 5 seconds, and the cured material bending strength was 152 MPa.

[0076] <Evaluation method for the ease of removing excess cement> The teeth of cattle extracted within 24 hours of slaughter were polished with P600 waterproof sandpaper under running water, and polished to a thickness of 1 cm parallel and flat against the lip surface. 2 The enamel was partially removed and kept warm in a 37°C constant temperature bath for 2 hours. Equal amounts of the first and second components were mixed and kneaded for 30 seconds to prepare dental cement. Immediately afterward, the cow tooth was removed from the constant temperature bath, 15 mg of the dental cement was applied to the enamel surface, and a 2 mm square aluminum plate was pressed onto the applied cement, allowing the cement to overflow around the aluminum plate (the overflowing cement becomes excess cement). A test sample was then prepared.

[0077] The surplus cement obtained in this way was then subjected to an irradiation intensity of 300 mW / cm². 2 Alternatively, 1200 mW / cm² 2 To achieve this, the distance between the excess cement and the tip of the light curing unit was adjusted, and light irradiation was performed.

[0078] Light irradiation was performed in the preparation of test samples, starting immediately after an aluminum plate was pressed against the applied cement, causing excess cement to squeeze out. The irradiation time was varied from 1 second to 5 seconds in 1-second increments. For each test sample irradiated with light at the above durations, an attempt was made to remove the excess cement by inserting a dental needle. The amount of excess cement that could be removed by adhering to the dental needle was evaluated according to the following criteria. A: The excess cement has a suitable hardness, allowing the short needle to smoothly penetrate it, and the excess cement can be efficiently removed as a large lump. B: The excess cement is slightly softer than the ideal hardness, so it can be peeled off the aluminum plate, but it cannot be removed in one piece with the needle. Alternatively, the excess cement has hardened too much and is slightly harder than the ideal hardness, so considerable force is required to insert the needle into the excess cement. C: The excess cement is considerably softer than the appropriate hardness, resulting in high fluidity. Therefore, even when a needle is inserted, the excess cement cannot be removed as a solid mass. Alternatively, the excess cement may have almost completely hardened, making it impossible to insert a needle.

[0079] <Evaluation of hardened material bending strength> The paste, kneaded for 10 seconds, was placed into a mold with a 2 x 2 x 25 mm rectangular prism-shaped hole. The mold was then sandwiched between polyethylene film and a glass slide, and pressed together with clips. Light was irradiated from five points on one side, for 20 seconds each, through the film and glass slide. The same process was followed on the other side. The irradiation intensity was set to 500 mW / cm² by adjusting the distance from the dental cement to the tip of the light curing unit. 2 The hardened material was removed from the mold, polished with P320 waterproof sandpaper, and immersed overnight in 37°C water to prepare the test specimen. The three-point bending fracture strength of this test specimen was measured using a universal testing machine (AG-I type, manufactured by Shimadzu Corporation) at a crosshead speed of 1.0 mm / min. Five test specimens were prepared, and the average of these was used as the bending strength.

[0080] Examples 2-15 and Comparative Examples 1-10 Parts 1 and 2 were prepared in the same manner as in Example 1, except that the types and contents of polymerization initiators and polymerization inhibitors were changed as shown in Tables 1 and 2.

[0081] Note that the parts by mass (numbers in parentheses) for each component shown in Tables 1 and 2 represent parts by mass relative to 50 parts by mass of polymerizable monomer (A) in the first component for the first component composition, and parts by mass relative to 50 parts by mass of polymerizable monomer (A) in the second component composition for the second component composition. In other words, the components other than the polymerization initiator and polymerization inhibitor are common to the first and second components in each example and comparative example, and the compositions of the first and second components in each example and comparative example are those obtained by blending the compounds shown in Table 1 into a base composition having the following composition. For example, the content of each component in the first component of Example 1 is as shown in Table 1: PyTU: 1 part by mass, CQ: 0.5 parts by mass, DMBE: 0.5 parts by mass, and BHT: 0.15 parts by mass, respectively. The "↑" in the table means the same as above.

[0082] • Composition of the base composition Polymerizable monomer (A) BisGMA: 6 parts by mass 3G: 19 parts by mass D-2.6E: 25 parts by mass Filler (B) F1:57 parts by mass F2:86 parts by mass

[0083] The two components prepared in this manner were mixed in equal amounts to prepare dental cement, and the ability to remove excess cement and the flexural strength of the hardened cement were evaluated in the same manner as in Example 1. The results are shown in Tables 3 and 4.

[0084] [Table 1]

[0085] [Table 2]

[0086] [Table 3]

[0087] [Table 4]

[0088] Examples 1 to 15 had compositions that satisfied the requirements of the present invention and exhibited good excess cement removal properties and high flexural strength.

[0089] In contrast, in Comparative Example 1, where x / y is less than 0.3 when the content of component (d1) is x parts by mass and the content of component (c2) is y parts by mass, and in Comparative Example 4, where the content of component (c2) exceeds 1.5 parts by mass per 100 parts by mass of component (A), the effect of component (c2) as a chain transfer agent was excessive, resulting in poor removal of excess cement at low irradiation intensity and short irradiation time.

[0090] Furthermore, in Comparative Example 2, where x / y exceeds 1.9; Comparative Example 3, where the content of component (c2) is less than 0.4 per 100 parts by mass of component (A); Comparative Example 6, where the content of component (d1) exceeds 0.8 per 100 parts by mass of component (A); and Comparative Example 8, where the content of component (d2) exceeds 0.8 per 100 parts by mass of component (A), the effect of component (c2) as a chain transfer agent was not sufficiently obtained, resulting in poor removal of excess cement at high irradiation intensity and long irradiation times.

[0091] Furthermore, in Comparative Example 5, where the content of component (d1) was less than 0.3 per 100 parts by mass of component (A), and in Comparative Example 7, where the content of component (d2) was less than 0.3 per 100 parts by mass of component (A), low bending strength was observed due to insufficient photopolymerization initiator.

[0092] Furthermore, in Comparative Example 9 and Example 10, which use non-containing aromatic amines corresponding to the dental cement disclosed in Patent Document 1, the removal of excess cement was poor at low irradiation intensity and short irradiation time due to inhibition of the photopolymerization reaction by the non-containing aromatic amines.

Claims

1. A dental cement comprising a composition containing a polymerizable monomer (A), a filler (B), a chemical polymerization initiator (C), and a photopolymerization initiator (D), The amount of filler (B) is 50 to 500 parts by mass per 100 parts by mass of polymerizable monomer (A). It substantially does not contain the tertiary aromatic amine represented by the following general formula (1), The chemical polymerization initiator (C) comprises, per 100 parts by mass of the polymerizable monomer (A), 0.2 to 3.5 parts by mass of hydroperoxide (c1) and 0.4 to 1.5 parts by mass of a thiourea compound (c2) represented by the following general formula (2). The photopolymerization initiator (D) consists of 0.3 to 0.8 parts by mass of α-diketone (d1) and 0.3 to 0.8 parts by mass of photopolymerization accelerator (d2) per 100 parts by mass of the polymerizable monomer (A). The ratio of the content (parts by mass) of the α-diketone (d1) to the content (parts by mass) of the thiourea compound (c2) is 0.3 to 1.

9. A dental cement characterized by the following features. 【Chemistry 1】 (In the formula, R ａ and R ｂ R is a C1-C6 alkyl group, which may be different from each other, or a C1-C6 substituted alkyl group having a hydroxyl group, nitro group, sulfone group, or halogen atom as a substituent, ａ and R ｂ At least one of them is the substituted alkyl group, R ｃ (where m is an alkyl group having 1 to 4 carbon atoms, and m is an integer from 0 to 3.) 【Chemistry 2】 (wherein, R １ , R ２ and R ３ are each a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, a heterocyclic group, an acyl group, an aralkyl group, or an alkenyl group, and R １ and R ２ may be bonded to each other to form a ring.)

2. A dental cement preparation kit comprising a first agent and a second agent, each packaged separately, for preparing the dental cement described in claim 1 by mixing the two agents, The aforementioned agent comprises the thiourea compound (c2) and the α-diketone (d1), The two agents include the hydroperoxide (c1) A dental cement preparation kit characterized by the following features.

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