Dental color-blocking material

Abstract

The present invention provides a dental color-blocking material comprising a photocurable composition containing a polymerizable monomer (A), inorganic powders and granules, and a white coloring agent (E), which exhibits good photocurability and can form a cured layer with excellent shielding properties. [Solution] An inorganic powder or granule with an average particle size within a specific range is used, and a portion of it (B) is used as is, while the remainder (c1) is compounded with a resin (c2) beforehand to form an organic-inorganic composite powder or granule (C) which is then blended. The blending amounts of (B) and (C) are set within a specific range, and the refractive index difference between the cured body (PA) of (A) and (B), the refractive index difference between PA and c1, the refractive index difference between PA and c2, and the refractive index difference between c2 and c1 are controlled to be within a specific range. Furthermore, the blending amount of (E) is set to be significantly less than the blending amount in conventional dental color-blocking materials.

Description

[Technical Field]

[0001] This invention relates to a dental color-blocking material. [Background technology]

[0002] Composite resin (hereinafter sometimes abbreviated as "CR"), used in dental filling treatments, is a photocurable composition containing polymerizable monomers and inorganic granules. Treatment using CR is generally performed by removing the carious portion of the tooth, preparing the cavity, filling the cavity with CR, and then hardening it. CR is also used for restoring anterior tooth crowns made of hard resin with metal backings and for direct veneers (a method of improving aesthetics by applying CR directly to the tooth surface or by thinly shaving the tooth surface and then hardening it) for discolored teeth that have turned brown or other discolored colors. When performing such anterior tooth crown restorations or direct veneers, dental color-blocking materials (sometimes called "opaque materials" or "opaque paste") are often used to conceal the color of the lining metal or the discolored tooth. When using dental color-blocking materials, a thin hardened layer of the dental color-blocking material is formed on the surface of the metal or discolored tooth, and then, as necessary, multiple layers of CR hardened material having a predetermined color are laminated on top of it to obtain the desired appearance color.

[0003] Dental color-blocking materials are photocurable compositions containing polymerizable monomers and inorganic powders, similar to CR, and their opacity is enhanced by incorporating a large amount of white coloring agents such as titanium dioxide to make them opaque. For example, Patent Document 1 discloses a set of dental metal color-blocking materials for forming a multilayer opaque layer, which includes two types of opaque materials 1 and 2 for the lower and upper layers. Both of these opaque materials contain polymerizable monomers, inorganic fillers, and opacities, but the shape of the inorganic fillers and the content of the opacities differ. Specifically, opaque material 1, which is disclosed, contains 60 to 150 parts by mass of amorphous inorganic fillers and 1 to 7 parts by mass of titanium dioxide, an opacity, per 100 parts by mass of polymerizable monomer, and the contrast ratio of the cured product is 0.60 to 0.80. Opaque material 2 contains 20 to 90 parts by mass of spherical inorganic fillers and 7 to 15 parts by mass of titanium dioxide, an opacity, per 100 parts by mass of polymerizable monomer, and the contrast ratio of the cured product is 0.91 to 0.97. Furthermore, Patent Document 2 discloses an opaque paste containing approximately 170 parts by mass of inorganic fillers and 5 parts by mass of titanium dioxide per 100 parts by mass of polymerizable monomer, with a contrast ratio of 0.92 for the cured product. The contrast ratio is an indicator of the transparency of the cured material, and is measured using a colorimeter on a white background using the Y value (Y) of a 0.1 mm thick sample. w Y value under a black background for ) (Y b ) Ratio: Y b / Y w This value is defined as such, and the closer it is to 1, the higher the opacity. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 6104664 [Patent Document 2] Patent No. 5072888 [Patent Document 3] International Publication No. 2018 / 043595 brochure [Overview of the project] [Problems that the invention aims to solve]

[0005] As mentioned above, dental opaque pastes are used to form a thin white opaque layer to conceal metallic or brownish undercoat colors. Conventional dental opaque pastes achieved their opacity by incorporating a large amount of white colorants, such as titanium dioxide colorants, to reduce transparency. As a result, increasing opacity reduced light transmittance, and depending on the thickness of the dental opaque paste layer and the application method, this could lead to reduced hardening in the underlying layer and subsequent hardening failure. For example, in cases with deep cavities, light may not reach deep enough, resulting in poor hardening.

[0006] Therefore, the present invention aims to provide a dental color-blocking material that can form a hardened layer with good photocurability and excellent shielding properties. [Means for solving the problem]

[0007] The present invention solves the above problems, and the first embodiment of the present invention is Polymerizable monomer component (A) consisting of one or more polymerizable monomers: 100 parts by mass, Inorganic powder (B): 50-100 parts by mass, composed of inorganic particles made of one or more types of inorganic materials, with an average particle diameter defined as the median diameter expressed as a volume fraction measured using a particle size distribution analyzer based on the principle of laser diffraction scattering, etc., of 70-1000 nm. Organic-inorganic composite powder (C) (C) (C2) (C2) (C1) (C1) (C1) (C1) (C1)) (C2) (C2) (C1) (C1) (C1) (C1) (C1) (C1) (C2)2) (C1) (C1) (C1) (C2) (C1) (C1) (C1) (C2) (C1) Photopolymerization initiator (D): 0.1 to 1 part by mass, and White coloring agent (E): 0.003 to 0.01 parts by mass A dental color-blocking material comprising a photopolymerizable and curable composition containing, Regarding the refractive index for sodium D line at 25°C: n, the refractive index of the polymer obtained by polymerizing the component (A) is n PA as, the refractive index of the (B) is n B as, the refractive index of the (c1) is n C1 as, the refractive index of the (c2) is n C2 when, the (A), (B), (c1) and (c2) satisfy all of the following formulas (1) to (4): 0.005 < |n PA - n B | < 0.050 (1) 0.005 < |n PA - n C1 | < 0.050 (2) 0.005 < |n PA - n C2 | < 0.050 (3) 0.005 < |n C2 - n C1 | < 0.030 (4) and satisfy all of the relationships shown, do not contain a solid component that becomes a component other than the (B), (C), (D) and (E), or contain 1 part by mass or less with respect to 100 parts by mass of the component (A), characterized in that it is a dental color masking material.

[0008] In the dental color masking material of the above form (hereinafter, also referred to as "the opaque material of the present invention"), the total content of the (B) and the (C) is 150 to 240 parts by mass, and the proportion of the (B) in the total content is 25 to 50% by mass, which is preferable.

[0009] Also, for the photocurable composition, the ratio of the Y value (Y w ) of black backgrounding to the Y value (Y b ) of white backgrounding measured using a color difference meter for a sample having a thickness of 0.1 mm composed of its cured product: Y b / Y wThe contrast ratio, defined as 0.35 to 0.45, and the brightness (L) measured for the sample using a C light source under a black background. * ) is 60-65, and saturation (C * It is preferable that the value is between 10 and 12.

[0010] Furthermore, the dental color-blocking material of the present invention preferably contains, in the photopolymerization initiator (D), 0.01 to 0.8 parts by mass of a tertiary amine compound (F) per 100 parts by mass of the polymerizable monomer component (A), and more preferably, the tertiary amine compound (F) contains an aromatic amine compound containing a dimethylamino group. [Effects of the Invention]

[0011] The opaque material of the present invention has the advantage of forming a hardened layer with good photocurability and excellent shielding properties. Therefore, it does not cause curing failure even when used in cases with deep cavities. [Modes for carrying out the invention]

[0012] 1. Outline of the present invention The present inventors considered whether the above problem could be solved by adapting a technique for deepening the curing depth known in CR, such as the one disclosed in Patent Document 3, and conducted an investigation. Specifically, Patent Document 3 describes a photocurable composition for dental fillings and restorative materials that has excellent light transmittance in the visible light region before curing and a deep curing depth, comprising "a polymerizable monomer component (A); an inorganic filler component (B) with an average particle size of 0.07 μm or more; an organic inorganic composite filler component (C) with an average particle size of 0.5 μm or more, containing an inorganic filler component (c1) and an organic polymer component (c2); and a photopolymerization initiator (D), and condition (X1), specifically, (i) the difference between the refractive index of (A) and the refractive index of (B), (c1), and (c2) is within a certain range, (ii) before Since a photocurable composition is disclosed that satisfies the following conditions: (A) the difference between the refractive index of the cured body and the refractive indices of (B), (c1), and (c2), and the difference between the refractive index of (c1) and the refractive index of (c2) are all within a certain range, and (iii) the difference between the refractive index of (B) and the refractive indices of (c1) and (c2) are all within a certain range, we considered that such a photocurable composition would not easily decrease in curability even if a large amount of white colorant is added, and we investigated the relationship between the refractive indices of each component and the amount added.

[0013] As a result, unlike CR, the thickness of dental color-blocking materials (opaque materials) when in use is usually 0.1 to 0.5 mm, and it is not very thick. Furthermore, it is not necessary for the hardened body to have a semi-transparent appearance similar to natural teeth. In addition, it is thought that the materials contain a large amount of white coloring agent. However, it is not necessary to satisfy all of the above conditions X1. We have found that by satisfying condition (ii) which relates to diffuse reflection and scattering at the interface between dissimilar materials in the hardened body, high opacity can be obtained even if the amount of white coloring agent is reduced, and consequently, the decrease in hardening properties can be suppressed. This led to the completion of the present invention.

[0014] In other words, the opaque material of the present invention is a dental color-blocking material comprising a photocurable composition, wherein the photocurable composition comprises components corresponding to each component (A) to (D) in the photocurable composition disclosed in Patent Document 3: polymerizable monomer component (A), inorganic powder having a specific average particle size (B), organic-inorganic composite powder having a specific average particle size (C), and photopolymerization initiator (D): 0.1 to 1 part by mass, in addition to a white coloring agent (E) as an essential component, wherein the blending ratio of these components is within a specific range, the difference between the refractive index of the cured body of (A) and the refractive indices of (c1) and (c2), which are materials constituting (B) and (C), is within a specific range, and the difference between the refractive index of (B) and the refractive indices of (c1) and (c2) is within a specific range, and furthermore, it is characterized in that it does not contain or contains very little solid components other than (B), (C), (D), and (E). The conditions that the above refractive index difference must satisfy correspond to condition (ii) of (X1) disclosed in Patent Document 3, which must satisfy the photocurable composition.

[0015] Here, dental color-blocking materials refer to materials used in so-called composite resin restorations to form a thin (for example, about 0.1 to 0.5 mm) shielding layer to shield the color of discolored teeth, or to form a thin shielding layer to shield the color of the lining metal or the color of discolored teeth when fabricating hard resin crown prostheses with metal linings.

[0016] As mentioned above, the components other than the colorant that constitute the opaque material of the present invention, and the conditions that the refractive index difference must satisfy, are basically the same as those of the photocurable composition disclosed in Patent Document 3. However, including these, the opaque material of the present invention will be described in detail below.

[0017] In this specification, unless otherwise specified, the notation "x~y" using numerical values ​​x and y means "greater 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. Furthermore, 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".

[0018] 2. Polymerizable monomer component (A) The polymerizable monomer component (A) in the opaque material of the present invention consists of one or more polymerizable monomers. While polymerizable monomers used in dental curable compositions can be used without particular limitation as the one or more polymerizable monomers constituting the polymerizable monomer component (A), it is preferable that they consist of (meth)acrylic compounds from the viewpoint of low biotoxicity and high polymerization activity. Furthermore, from the viewpoint of the mechanical properties of the cured product (e.g., strength and water resistance) and adhesion to tooth structure, it is preferable that the polymerizable monomer component (A) contains 60 to 100% by mass, particularly 70 to 100% by mass, of a polyfunctional (meth)acrylic compound containing at least two polymerizable groups. If necessary, radical polymerizable monomers other than the above-mentioned (meth)acrylate monomers may also be used.

[0019] Examples of polyfunctional (meth)acrylic compounds that can be suitably used include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, tridecaethylene glycol dimethacrylate, tetradecaethylene glycol dimethacrylate, hexamethylenediol dimethacrylate, nonamethylenediol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, 1,6-bis(methacrylethyloxycarbonylamino)trimethylhexane, 2,2-bis(4-methacryloyloxypolyethoxyphenyl)propane, 2,2-bis(methacryloyloxyphenyl)propane, and 2,2-bis[4-(3-methacryloyloxy)-2-hydroxypropoxyphenyl]propane.

[0020] Furthermore, examples of monofunctional (meth)acrylic compounds that can be used in combination with polyfunctional (meth)acrylic compounds include methyl (meth)acrylate, ethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, glyceryl monomethacrylate, 1,2,4-benzenetricarboxylic acid 4-[2-(methacryloyloxy)ethyl], 1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid 2-methacryloyloxyethyl, 11-(meth)acryloyloxy-1,1-undecanedicarboxylic acid, 12-methacryloyldodale phosphate, and γ-methacryloyloxypropyltrimethoxysilane.

[0021] Including the (meth)acrylic compounds mentioned above, the refractive index of polymerizable monomers used in dental curable compositions is usually within the range of 1.380 to 1.550, so even when component (A) consists of a mixture of these, it will also be within the above range. Furthermore, the refractive index of the cured product obtained by polymerizing and curing component (A) consisting of (meth)acrylic compounds is n PA Typically, the refractive index of component (A) is n AIt is known to be slightly higher than that, in the range of 1.400 to 1.570. Furthermore, the cured body of component (A) itself is basically transparent, and in the cured body of the opaque material of the present invention, (B), (C), and (E) are dispersed in a matrix consisting of the cured body of component (A). Therefore, by satisfying the relationship of formulas (1) to (4) above, the transparency of the cured body is reduced by diffuse reflection and scattering at the interface between the matrix and (big amounts of dispersed) (B) and (C), and good shielding properties can be obtained even if the amount of (E) is reduced. Formula (4) above strikes a balance between not significantly reducing the transparency of the composition before curing and maximizing the effects of scattering after curing, and this also exhibits an effect of suppressing the decrease in curability.

[0022] 3.Inorganic powder (B) The opaque material of the present invention is composed of inorganic particles made of one or more types of inorganic materials, and has an average primary particle diameter of 70 to 1000 nm as measured by scanning electron microscopy, and furthermore, in relation to the above component (A), the above formula (1): 0.005 < |n PA -n B It contains inorganic granular material (B) that satisfies the relationship |<0.050.

[0023] Here, the refractive index of the inorganic granule (B) is n B This means that if the inorganic powder (B) is composed of inorganic particles made of one type of inorganic material, it will be the refractive index of that inorganic material, but if it is composed of inorganic particles made of multiple types of inorganic materials, it will be the refractive index of each inorganic material. In other words, the relationship in equation (1) above must be satisfied for all inorganic particles of all materials that make up the inorganic powder (B). For example, if the inorganic powder (B) has a refractive index of n B1 A powder B1 consisting of one type of inorganic material, and a refractive index n B2 Powdered material B2 consists of one type of inorganic material, and has a refractive index of n B3 When the mixture consists of a powder B3 made of one type of inorganic material, then with respect to formula (1), 0.005 < |n PA -n B1 |<0.050, 0.005<|n PA -nB2 |<0.050 and 0.005<|n PA -n B3 The relationship |<0.050 must be satisfied for all conditions.

[0024] If the relationship in equation (1) above is not satisfied, it will be difficult to obtain sufficient shielding. (B) is given by the following equation (1'): 0.006<|n PA -n B |<0.03 (1') It is more preferable that the object satisfies the given relationship.

[0025] As the inorganic powder (B), various inorganic powders used as fillers for dental curable compositions can be used, provided that they are selected to satisfy the relationship shown in formula (1) above, but their average particle size must be 70 to 1000 nm. Here, the average particle size refers to the median diameter value expressed as a volume fraction measured using a particle size distribution analyzer based on the principle of laser diffraction scattering.

[0026] If the average particle size is less than 70 nm, the particle size is smaller than the wavelength of visible light, and therefore, a sufficient shielding effect cannot be obtained unless the amount of white pigment added is increased. Furthermore, if the average particle size exceeds 1000 nm, not only may the mechanical properties of the resulting cured product deteriorate, but the desired photocuring depth may not be achieved. From the viewpoint of effectiveness, an average particle size of 100 to 500 nm is preferable.

[0027] As inorganic materials for the particles constituting the inorganic powder (B), oxides and composite oxides of silicon, aluminum, zirconium, tin, lanthanides, yttrium, etc.; fluorides such as ytterbium fluoride and yttrium fluoride; silicate glass, fluoroaluminosilicate glass, etc. can be used. Among these, silica composite oxides, represented by silica-zirconia and silica-titania, are particularly suitable because the refractive index can be adjusted according to the silica content, making it easy to satisfy specific conditions. These composite oxides may also contain alkali metals such as sodium, potassium, magnesium, and calcium, or alkaline earth metals.

[0028] Furthermore, by surface-treating the inorganic powder (B) described above with a silane coupling agent such as γ-methacryloyloxypropyltrimethoxysilane, the compatibility with polymerizable monomers can be improved, thereby enhancing the mechanical strength and water resistance of the resulting cured product.

[0029] The amount of inorganic powder (B) in the opaque material of the present invention must be 50 to 100 parts by mass per 100 parts by mass of the polymerizable monomer component (A). If the amount is less than 50 parts by mass, the viscosity decreases, and sedimentation of the organic-inorganic composite powder is likely to occur in the paste. If it exceeds 100 parts by mass, the viscosity increases, making it difficult to uniformly form a thin shielding layer. From the viewpoint that the desired shielding performance cannot be obtained if a uniform film cannot be formed, the amount of inorganic powder (B) is preferably 50 to 100 parts by mass.

[0030] 4.Organic-inorganic composite powder (C) The opaque material of the present invention is composed of inorganic particles made of one or more types of inorganic materials, and includes an organic-inorganic composite powder (C) having an average particle size of 5 to 50 μm, which is composed of organic-inorganic composite particles made of a composite of inorganic powder (c1) having an average particle size of 70 to 1000 nm and a resin (c2).

[0031] The above composite is obtained by curing a mixture of a polymerizable monomer that serves as the raw material for (c2) and (c1), or by impregnating the polymerizable monomer that serves as the raw material for (c2) into microporous aggregated particles made of inorganic particles constituting (c1) and then curing them, wherein (c2) usually consists of a cured polymerizable monomer. The ratio of (c2) to (c1) in the composite is expressed as the percentage of (c1) in the total mass of both (mass%), and is usually 70 to 90% by mass, preferably 75 to 85% by mass.

[0032] Furthermore, the polymerizable monomer used as the raw material for (c2) can be any polymerizable monomer that can be used as the polymerizable monomer (A) exemplified earlier, and the inorganic powder or granule that can be used as the inorganic powder or granule (B) exemplified earlier can be used for (c1), and the preferred embodiments are the same as the preferred embodiments for (A) and (B).

[0033] However, the inorganic powder (c1) and the resin (c2) must satisfy the relationships shown in formulas (2) to (4). If these relationships are not satisfied, it will not only be difficult to obtain good shielding properties, but the curability will also tend to decrease. With respect to formulas (2) and (4), as with formula (1), if (c1) is composed of inorganic particles made from multiple types of inorganic materials, the relationships shown in formulas (2) and (4) must be satisfied for all inorganic particles of all materials constituting (c1). From the viewpoint of effectiveness, it is more preferable that (c1) and (c2) satisfy the relationships shown in formulas (2') to (4') below.

[0034] 0.01<|n PA -n C1 |<0.03 (2') 0.02<|n PA -n C2 |<0.04 (3') 0.01<|n C2 -n C1 |<0.02 (4') Furthermore, the average particle size of the organic-inorganic composite powder (C) needs to be 5 to 50 μm, and preferably 10 to 20 μm, from the viewpoint of effectiveness and the strength of the resulting hardened product.

[0035] The amount of organic-inorganic composite powder (C) in the opaque material of the present invention must be 100 to 140 parts by mass per 100 parts by mass of the polymerizable monomer component (A). If the amount is less than 100 parts by mass, the viscosity will increase, making it difficult to uniformly form a thin shielding layer. If it exceeds 140 parts by mass, the viscosity will decrease, making it easier for the organic-inorganic composite powder to settle in the paste. From the viewpoint that the desired shielding properties cannot be obtained if a uniform film cannot be formed, the amount of organic-inorganic composite powder (C) is preferably 100 to 140 parts by mass.

[0036] 5. Photopolymerization initiator (D) In the opaque material of the present invention, the photopolymerization initiator (D) is a component added to polymerize and cure the polymerizable monomer component (A) described above by light irradiation. Suitable photopolymerization initiators include photosensitizers or combinations of photosensitizers with polymerization accelerators (reducing agents) and / or photoacid generators. While the amount of such photopolymerization initiator added should be an effective amount, from the viewpoint of minimizing the effect of light transmission inhibition by the polymerization initiator itself and ensuring a large photocuring depth, the amount is set at 0.1 to 1 part by mass per 100 parts by mass of the polymerizable monomer component (A).

[0037] The wavelength of light irradiated for this polymerization curing is usually in the visible light range for safety reasons. Therefore, the photopolymerization initiator used has an excitation absorption wavelength range, particularly an excitation maximum absorption wavelength range, in the visible light range of 380 to 500 nm (preferably 400 to 500 nm).

[0038] As photosensitizers, among the above-mentioned photoradical generators, α-diketones and bisacylphosphine oxides are preferred from the viewpoint of good polymerization activity and low harm to living organisms, and camphorquinone and 2,4,6-trimethylbenzoyldiphenylphosphine oxide are more preferred. Incidentally, the excitation maximum absorption wavelength of camphorquinone is 470 nm, and the excitation maximum absorption wavelength of 2,4,6-trimethylbenzoyldiphenylphosphine oxide is 380 nm.

[0039] Polymerization accelerators (reducing agents) function as polymerization accelerators that enhance curability, and can be tertiary amine compounds (F) such as aliphatic tertiary amine compounds and aromatic tertiary amine compounds, aldehydes, and sulfur-containing compounds. Among these, it is preferable to include at least one aromatic tertiary amine compound from the viewpoint of odor, and it is even more preferable to include at least one aromatic tertiary amine compound having a dimethyl aquino group from the viewpoint of obtaining high polymerization activity. The amount of tertiary amine compound added should be an effective amount, but from the viewpoint of minimizing the effect of inhibiting light transmission by itself and ensuring a large photocuring depth, it is preferable to add 0.01 to 0.8 parts by mass, particularly 0.05 to 0.5 parts by mass, per 100 parts by mass of the polymerizable monomer component (A).

[0040] Examples of suitably usable tertiary amine compounds (F) include aliphatic tertiary amine compounds such as triethylamine, triethanolamine, tributylamine, triallyamine, N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, N-methyldiethanolamine, N-ethyldiethanolamine, triethanolamine, and tri(isopropanol)amine; N,N-dimethylaniline, N,N-dimethyl-p-toluidine, N,N-diethyl-p-toluidine, p-(N,N-dimethyl)aminobenzoate methyl, p-(N,N-dimethyl)aminobenzoate ethyl, p-(N Examples include aromatic tertiary amine compounds having a dimethylaquino group, such as amyl N-dimethylaminobenzoate, isoamyl 4-(dimethylamino)benzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 4'-dimethylaminoacetophenone, 4-(dimethylamino)benzophenone, 4,4'-bis(dimethylamino)benzophenone, 4-(dimethylamino)benzonitrile, 4-dimethylaminobenzoic acid, N,N-dimethyl-4-(trifluoromethyl)aniline, N,N-dimethyl-4-nitroaniline, methyl 2-(dimethylamino)benzoate, and methyl 3-(dimethylamino)benzoate.

[0041] Examples of photoacid generators include diaryliodonium salt compounds, sulfonium salt compounds, sulfonic acid ester compounds, and halomethyl-substituted S-triazine derivatives and pyridinium salt compounds.

[0042] 6. White coloring agent (E) The opaque material of the present invention contains 0.003 to 0.01 parts by mass of a white coloring agent (E) per 100 parts by mass of the polymerizable monomer component (A).

[0043] As white pigments, inorganic pigments such as titanium dioxide, zinc oxide, lead carbonate base, and lithopone (a mixture of barium sulfate and zinc sulfide) can be suitably used, and among these, titanium dioxide is the most suitable from the viewpoint of its high shielding effect. These inorganic pigments take the form of powders and granules, but their refractive index is at least around 1.63 (for example, the refractive index of titanium dioxide (rutile) is around 2.9), and therefore, regardless of their average particle size, they do not fall under the category of inorganic powders and granules (B) of the present invention.

[0044] While these white pigments have very high light-shielding properties, they also have a high effect of reducing (shallowing) the depth of light curing. In the opaque material of the present invention, by satisfying the relationship of formulas (1) to (4) above, a shielding effect due to light scattering, etc., is obtained. Therefore, by reducing the amount of white pigment used and using other colorants that have a significantly smaller effect on the depth of light curing and, consequently, the curing properties (compared to white pigments), a decrease in curing properties is prevented.

[0045] In the present invention, the opaque material can reliably achieve the desired effect even when applied to deep cavities formed in the molar region. Therefore, the Y value (Y) under a white background is measured using a colorimeter with a C light source for a 0.1 mm thick sample made of the hardened body of the present invention. w Y value under a black background for ) (Y b ) Ratio: Y b / Y w The contrast ratio, defined as 0.35 to 0.45, and the brightness (L) measured for the sample using a C light source under a black background. * ) is 60-65, saturation (C * It is preferable to reduce the amount of coloring agent added so that the ratio is between 10 and 12.

[0046] 7. Other ingredients In the opaque material of the present invention, from the viewpoint of maintaining a balance between the shielding effect due to light scattering, etc., of (B) and (C) and the shielding effect due to (E), it is necessary that the material does not contain solid components other than (B), (C), (D), and (E), such as inorganic powders and granules with an average particle diameter of 70 to 1000 nm that do not satisfy the relationship of formula (1) above, or inorganic powders and granules with an average particle diameter of less than 70 nm, or if it does contain solid components, the total amount thereof must be 1 part by mass or less, preferably 0.5 parts by mass or less, per 100 mass of component (A).

[0047] Assuming these conditions are met, the opaque material of the present invention may, as necessary, contain "other components" other than the above components (A) to (E), such as colorants other than the white colorant (E), polymerization inhibitors, ultraviolet absorbers, viscosity modifiers, etc., to the extent that they do not impair the effects of the present invention.

[0048] In addition, colorants other than white pigments may be pigments or dyes, but from the viewpoint of effectiveness, it is preferable to use organic pigments. Examples of organic pigments that can be suitably used include yellow pigments such as Pigment Yellow 95, Pigment Yellow 97, and Pigment Yellow 109; red pigments such as Pigment Red 166, Pigment Red 202, and Pigment Red 242; and blue pigments such as Pigment Blue 1, Pigment Blue 15, and Pigment Blue 60.

[0049] 8. Method for manufacturing and using the opaque material of the present invention The opaque material of the present invention is prepared by a manufacturing method similar to that used for dental curable compositions. Specifically, a photopolymerization initiator (D), polymerization inhibitor, ultraviolet absorber, viscosity modifier, etc., are added to a specified amount of polymerizable monomer component (A) and mixed to prepare a uniform polymerizable monomer composition. Next, predetermined amounts of inorganic powder (B) and organic-inorganic composite powder (C) are weighed out and gradually added to the polymerizable monomer composition under red light. The mixture is then kneaded using a planetary mixer (manufactured by Inoue Seisakusho) to prepare a uniform curable paste. A white coloring agent (E) is then added and kneaded until uniform. The paste is then degassed under reduced pressure to remove air bubbles and produce a photopolymerizable curable composition. The obtained photopolymerizable curable composition can be filled into a syringe container to produce the opaque material of the present invention.

[0050] The opaque material of the present invention can be used to conceal the discoloration of teeth caused by staining substances or caries, or to conceal metallic colors when repairing fractured prostheses or other dental restorations. Specifically, after treating the substrate with a bonding agent according to its material, the opaque material of the present invention is applied thinly (0.1 to 0.5 mm) and uniformly, then light-cured using a dental polymerization light curing unit. By then layering a dental curing composition such as composite resin on top, discolored teeth and fractured prostheses can be repaired. [Examples]

[0051] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0052] First, the various raw materials used in the examples and comparative examples are listed below.

[0053] [polymerizable monomers] · bis-GMA; 2,2-bis[4-(3-methacryloyloxy)-2-hydroxypropoxyphenyl]propane • 3G; Triethylene glycol dimethacrylate UDMA; 1,6-bis(methacrylateethyloxycarbonylamino)trimethylhexane.

[0054] [Photopolymerization initiator] Photosensitizer CQ; Camphorquinone Polymerization accelerators (reducing agents): Tertiary amine compounds • DMBE; ethyl N,N-dimethyl-p-benzoate DMB; 4-(dimethylamino)benzophenone • DMA; 4'-dimethylaminoacetophenone DMBA; 4-dimethylaminobenzoic acid • DMNA; N,N-dimethyl-4-nitroaniline ·2-DMBM; methyl 2-(dimethylamino)benzoate · 3-DMBM; methyl 3-(dimethylamino)benzoate.

[0055] [Thermal polymerization initiator] AIBN; Azobisisobutyronitrile.

[0056] [Polymerization inhibitor] HQME; Hydroquinone monomethyl ether.

[0057] [Coloring agent] • White pigment: Titanium dioxide (average particle size: 0.25 μm).

[0058] 1. Preparation and Analysis of Polymerizable Monomer Component Compositions The polymerizable monomers described above were mixed in the mass ratios shown in Table 1 to prepare polymerizable monomer component (A) to be used in the examples and comparative examples. Next, 100 parts by mass of polymerizable monomer component (A) were mixed with a photopolymerization initiator (D) consisting of 0.2 parts by mass of CQ, 0.3 parts by mass of various tertiary amine compounds (F) shown in Table 1, and 0.15 parts by mass of HQME as a polymerization inhibitor to prepare homogeneous polymerizable monomer component compositions (base monomer compositions): M1 to M11. Each base monomer composition was placed in a mold having a φ7 mm × 0.5 mm hole, and polyester film was pressed onto both sides, followed by exposure to light at a light intensity of 500 mW / cm².2 Samples consisting of cured bodies of each base monomer composition were prepared by irradiating them with light for 30 seconds using a halogen-type dental light curing unit (Demetron LC, manufactured by Cybron). The refractive index of the samples with respect to sodium D lines at 25°C was then measured using an Abbe refractometer (manufactured by Atago). PA The following measurements were taken. During the measurement, the sample was not dissolved when setting up the sample, and a solvent with a higher refractive index than the sample (bromonaphthalene) was added to the sample to ensure close contact between the sample and the measurement surface. The measurement results are shown in Table 1.

[0059] [Table 1]

[0060] 2. Preparation and Analysis of Inorganic Powders and Granules For the inorganic powders F-1 to F-4 used in the examples and comparative examples, their composition, particle shape, average particle diameter, and refractive index n at 25°C are described below. B Table 2 shows the results. Note that the refractive index n of the inorganic powder (or mixture of inorganic powders) used is n. B The refractive index was measured using an Abbe refractometer (manufactured by Atago) by the immersion method. Specifically, in a constant temperature room at 25°C, 1 g of inorganic powder (or inorganic powder mixture) or its surface-treated material was dispersed in 50 ml of anhydrous toluene in a 100 ml sample bottle. While stirring this dispersion with a stirrer, 1-bromotoluene was added dropwise little by little, and the refractive index of the dispersion was measured when it became the clearest, and the obtained value was taken as the refractive index of the inorganic powder.

[0061] [Table 2]

[0062] 3. Preparation and Analysis of Organic-Inorganic Composite Powders and Granules The preparation methods for the organic-inorganic composite powders CF-1 to CF-3 used in the examples and comparative examples are shown below. The composition, average particle size, and refractive index of each component of CF-1 to CF-3 are shown in Table 3. Note that the refractive index of C1 is n c1is the refractive index: n of F-1 and F-3 used as C1 B and corresponds thereto. Also, the refractive index: n of C2 c2 is the refractive index: n of M-4 and M-5 used as C2 PA and corresponds thereto.

[0063] <Preparation Method of CF-1> 100 g of inorganic powder F-1 was added to 200 g of water, and an aqueous dispersion thereof was obtained using a circulation type grinder, SC mill (manufactured by Nippon Coke Industry Co., Ltd.). On the other hand, 4 g (0.016 mol) of γ-methacryloyloxypropyltrimethoxysilane and 0.003 g of acetic acid were added to 80 g of water and stirred for 1 hour and 30 minutes to obtain a uniform solution with a pH of 4. This solution was added to the above inorganic powder dispersion and mixed until uniform. Thereafter, while gently mixing the dispersion, it was supplied onto a rotating disk and granulated by spray drying. The spray drying was carried out using a spray dryer TSR-2W (manufactured by Sakamoto Giken Co., Ltd.) equipped with a rotating disk and atomized by centrifugal force. The rotation speed of the disk was 10,000 rpm, and the temperature of the drying atmosphere air was 200°C. Thereafter, the powder obtained by granulation by spray drying was vacuum dried at 60°C for 18 hours to obtain 73 g of spherical aggregates. Next, 1.78 g of M-4 as a polymerizable monomer, 0.005 g of AIBN as a thermal polymerization initiator, and 5.0 g of methanol as an organic solvent were mixed to prepare a polymerizable monomer solution (containing 35.6 parts by mass of the polymerizable monomer with respect to 100 parts by mass of the organic solvent), and 10.0 g of the above aggregates were immersed therein. After sufficient stirring and confirming that this mixture had become a slurry state, it was allowed to stand for 1 hour. The above mixture was transferred to a rotary evaporator. Under stirring conditions, the mixture was dried for 1 hour under a reduced pressure of 10 hectopascals and heating conditions of 40°C (using a warm water bath) to remove the organic solvent. When the organic solvent was removed, a highly fluid powder was obtained. This powder showed no agglomeration. The obtained powder was heated for 1 hour under the conditions of a reduced pressure of 10 hectopascals and a heating condition of 100 °C (using an oil bath) while stirring with a rotary evaporator, thereby polymerizing and curing the polymerizable monomer in the powder. By this operation, 8.3 g of spherical organic-inorganic composite powder particles in which the surface of the spherical aggregates was coated with an organic polymer were obtained.

[0064] <Preparation method of CF-2 and CF-3> CF-2 was prepared in the same manner as CF-1, except that the inorganic powder particles (c1) and the resin (c2) were those shown in Table 3.

[0065] In the following Examples and Comparative Examples, the refractive index n of the polymer obtained by polymerizing the polymerizable monomer (A) at 25 °C PA and the refractive index n of the resin in the organic-inorganic composite powder particles c2 as well as the refractive index n of the inorganic powder particles at 25 °C B and the refractive index n of the inorganic powder particles in the organic-inorganic composite powder particles c1 were measured as follows.

[0066]

Table 3

[0067] Example 1 To matrix M-1, which is the polymerizable monomer (A), 0.2 parts by mass of CQ (photoinitiator), 0.3 parts by mass of DMBE (tertiary amine compound), and 0.15 parts by mass of HQME (polymerization inhibitor) were added and mixed to separately prepare a uniform base monomer M-1.

[0068] Next, 100 parts by mass of inorganic powder particles F-1 as component (B) and 100 parts by mass of organic-inorganic composite powder particles CF-1 as component (C) were weighed into a mortar, and the above base monomer composition: M-1 was gradually added under red light, and kneaded well in the dark to obtain a uniform paste. Further, 0.003 parts by mass of a white colorant (E) was added and kneaded. This paste was defoamed under reduced pressure to remove air bubbles, and a paste-like photocurable composition was obtained. The obtained photocurable composition was subjected to the following methods to determine its shielding properties and brightness (L * ), saturation (C * The contrast ratio, photocuring depth, and shielding properties were evaluated. The composition of the photocurable composition is shown in Table 4, and the evaluation results are shown in Table 5.

[0069] (1) Lightness (L * ), saturation (C * ) and evaluation of contrast ratio The prepared photocurable composition paste was placed in a mold with a φ25 mm × 0.1 mm hole, and polyester film was pressed onto both sides. Light intensity: 400 mW / cm² 2 The sample was irradiated for 40 seconds using the LED light curing unit "Ellipper S10" (manufactured by 3M). For the 0.1 mm thick sample made from the resulting cured material, the brightness (L) against a black background with a C light source was measured using the color difference meter "SE7700" (manufactured by Nippon Denshoku Co., Ltd.). * ) and chromaticity (a * , b * ) Based on the following formula, saturation (C * ) was calculated. C * ={(a * ) 2 +(b * ) 2} 1 / 2 Furthermore, for the above-mentioned sample with a thickness of 0.1 mm, the Y value (Y) against a white background was determined using the above-mentioned colorimeter. w ) and the Y value for black background (Y b ) was measured, and the ratio of the two: Y b / Y w The contrast ratio, defined as [the specified value], was determined.

[0070] (2) Evaluation of shielding performance Using the A3 shade of the dental composite resin "Estelite Sigma Quick" (manufactured by Tokuyama Dental Corporation), a cured body with a diameter of 15 mm and a thickness of 1 mm was prepared, and this was used as a non-discoloring base sample. Separately, in the center of the non-discoloring base sample prepared, 0.001 g of the shade adjusting material "Estelite Color" (manufactured by Tokuyama Dental Corporation) in the dark brown (DBr) shade was applied in a diameter of 7 mm and cured to form a discoloring base sample with a discoloring area on the surface. Next, the prepared photocurable composition was applied to the central surface of the non-discoloring base sample and the central surface of the discoloring area of the discoloring base sample to a thickness of 0.3 mm each, and then irradiated with light of 400 mW / cm 2 for 40 seconds with an LED light irradiator "Elipar S10" (manufactured by 3M) to photocure and prepare measurement samples corresponding to each base. For the obtained measurement samples, using a color difference meter "SE7700" (manufactured by Nippon Denshoku Industries Co., Ltd.), the lightness (L * ) and chromaticity (a * , b * ) were measured, and Formula: ΔE * ={(ΔL * ) 2 +(Δa * ) 2 +(Δb * ) 2} 1 / 2 was used to obtain the color difference: ΔE * . In the above formula, ΔL * , Δa * and Δb * mean the difference in the measured values of both samples for each parameter value. The smaller ΔE * , the higher the shielding property of the discoloring area of the discoloring base sample. Also, the cured parts of the photocurable composition of both measurement samples were visually observed, and the degree of shielding was evaluated according to the evaluation criteria of ◎ = shielded, 〇 = slightly shielded, △ = slightly unshielded, × = unshielded.

[0071] (3) Evaluation of photocuring depth In accordance with JIS T6514:2015, a paste-like photocurable composition was prepared and filled into a stainless steel split mold with a φ4mm x 10mm deep hole, then pressed with a polypropylene film, and a light intensity of 400mW / cm² was applied from above. 2 The material was cured by irradiating it with a 3M LED light curing unit, "Ellipper S10," for 40 seconds. After curing, the cured material was removed from the mold, the uncured paste was removed with a spatula, and the thickness of the cured portion was measured with a micrometer. Half of the measured value was defined as the photocuring depth. The test was performed three times, and the average value was evaluated as the photocuring depth.

[0072] Examples 2-13 A paste-like photocurable composition was prepared in the same manner as in Example 1, except that the types and amounts of the separately prepared base monomer composition, the inorganic powder (B), and the organic-inorganic composite powder (C) were changed as shown in Table 4, and various physical properties were evaluated. The evaluation results are shown in Table 5.

[0073] [Table 4]

[0074] [Table 5]

[0075] Comparative Examples 1-11 Except for changing the types of the separately prepared base monomer composition, the inorganic powder (B), and the organic-inorganic composite powder (C) as shown in Table 6, a photocurable composition was prepared in the same manner as in Example 1, and various physical properties were evaluated. The evaluation results are shown in Table 7.

[0076] [Table 6]

[0077] [Table 7]

[0078] As shown in Table 5, in Examples 1 to 13, a good shielding effect was obtained while the photocuring depth was 0.5 mm or more. In contrast, as shown in Tables 6 and 7, in Comparative Examples 1 to 3, which fell below the lower limit of any one of the formulas (1) to (3), the desired light diffusion was not obtained, the contrast ratio was low (high transparency), and sufficient shielding was not achieved. Furthermore, in Comparative Example 4, which used (B) with an average primary particle diameter exceeding 1 μm and exceeded the upper limit of formula (1), opacity due to Mie scattering was observed, and a decrease in photocuring depth was seen. Also, in Comparative Example 5, where the amount of white colorant was below the lower limit, sufficient shielding was not obtained. Conversely, in Comparative Example 6, where the amount of white colorant was above the upper limit, the photocuring depth decreased. Furthermore, in Comparative Example 7, which did not satisfy the relationship of formula (4), the desired light diffusion was not obtained, the contrast ratio was low (high transparency), and sufficient shielding was not achieved. Furthermore, regarding the content of (B), in Comparative Example 8, where the amount was below the lower limit, and in Comparative Example 9, where the amount was above the upper limit, uniform shielding could not be achieved, and therefore the desired shielding performance could not be obtained. In addition, regarding the content of (C), in Comparative Example 10, where the amount was below the lower limit, and in Comparative Example 11, where the amount was above the upper limit, uniform shielding could not be achieved, and therefore the desired shielding performance could not be obtained.

Claims

1. Polymerizable monomer component (A) consisting of one or more polymerizable monomers: 100 parts by mass, Inorganic powder (B): 50 to 100 parts by mass, composed of inorganic particles made of one or more types of inorganic materials, with an average particle diameter defined as the median diameter expressed as a volume fraction measured using a particle size distribution analyzer based on the principle of laser diffraction scattering, etc., of 70 to 1000 nm. Organic-inorganic composite particles (C) composed of inorganic particles made of one or more types of inorganic materials, wherein the inorganic powder (c1) has an average particle diameter of 70 to 1000 nm and is composed of a composite of inorganic powder (c1) and resin (c2), wherein the organic-inorganic composite powder (C) has an average particle diameter of 5 to 50 μm: 100 to 140 parts by mass, Photopolymerization initiator (D): 0.1 to 1 part by mass, and White coloring agent (E): 0.003 to 0.01 parts by mass A dental color-blocking material comprising a photopolymerizable and curable composition containing, For the refractive index n of the sodium D line at 25°C, The refractive index of the polymer obtained by polymerizing component (A) is n ＰＡ year, The refractive index of (B) above is n Ｂ year, The refractive index of (c1) is n Ｃ１ year, The refractive index of (c2) is n Ｃ２ In that case, The above (A), (B), (c1) and (c2) are given by the following formulas (1) to (4): 0.005<|n ＰＡ -n Ｂ |<0.050 (1) 0.005<|n ＰＡ -n Ｃ１ |<0.050 (2) 0.005<|n ＰＡ -n Ｃ２ |<0.050 (3) 0.005<|n Ｃ２ -n Ｃ１ |<0.030 (4) Satisfying all the relationships shown, It does not contain any solid components other than those described in (B), (C), (D), and (E), or it contains 1 part by mass or less per 100 mass of component (A). A dental color-blocking material characterized by the following features.

2. The dental color-blocking material according to claim 1, wherein the total content of (B) and (C) is 150 to 240 parts by mass, and the proportion of (B) in the total content is 25 to 50% by mass.

3. The aforementioned photopolymerizable curable composition is measured using a colorimeter with a thickness of 0.1 mm using a C light source to obtain the Y value (Y) under a white background. ｗ ) Y value under a black background (Y ｂ ) Ratio to: Y ｂ / Y ｗ The contrast ratio, defined as such, is 0.35 to 0.45, and the brightness (L) measured for the sample using a C light source under a black background is also determined. * ) is 60-65, and saturation (C * A dental color-blocking material according to claim 1 or 2, wherein the ratio is 10 to 12.

4. The dental color-blocking material according to claim 1, wherein the photopolymerization initiator (D) contains 0.01 to 0.8 parts by mass of a tertiary amine compound (F) per 100 parts by mass of the polymerizable monomer component (A).

5. The dental color-blocking material according to claim 4, wherein the tertiary amine compound (F) comprises an aromatic amine compound containing a dimethylamino group.

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