Dental hardenable composition and method for producing the same

Abstract

To provide a dental hardenable composition comprising a base composition containing a polymerizable monomer (A), an organic-inorganic composite powder particle (B), an inorganic powder particle (C), and a polymerization initiator (D) in predetermined amounts, the dental hardenable composition having a highly improved brightness and a color tone suitable for whitening tooth restoration.SOLUTION: As (C), a powder particle containing 60 mass% or more of core-shell type spherical silica-based composite oxide powder particles having an average primary particle diameter of 350 to 600 nm and composed of spherical particles having a spherical core made of silica and a silica-based composite oxide coating layer covering the outer surface of the spherical core is used, and further, 50 to 1000×10-6 pts.mass of a white colorant (e1) and 0.01 to 3×10-6 pts.mass of a blue colorant (e2) are blended with respect to 1 pt.mass of the base composition so that the yellowness and transparency of the cured product fall within predetermined ranges.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a dental hardenable composition that can be suitably used as a dental composite resin suitable for restoring whitened natural teeth. [Background technology]

[0002] Direct bonding using dental composite resins (hereinafter simply referred to as "CR"), a dental curable composition, is one of the most frequently performed treatments in clinical practice due to its minimal invasiveness and aesthetic restoration. Composite resins are generally composed of polymerizable monomers, polymerization initiators, additives, and inorganic powder fillers. Various colors (shades) are available to match the color of the tooth using pigments. The color (shade) of CR (specifically, its cured form) is typically adjusted by varying the amount and ratio of white pigments such as titanium dioxide and yellow, red, and blue pigments. CRs are available in various types: Type A (reddish-brown), Type B (reddish-yellow), Type C (gray), and Type D (reddish-gray).

[0003] On the other hand, the properties of a paste-like CR (dental curable composition) (before hardening), such as its ease of handling and polymerization shrinkage, as well as the aesthetics and mechanical strength of the cured product, are affected by the form of the inorganic filler blended in. CRs that exhibit these properties are known to use fillers (organic-inorganic composite fillers) made of organic-inorganic composite particles that are a composite of fine inorganic powder and resin (see, for example, Patent Documents 1 and 2). By using such CRs, the use of an organic-inorganic composite filler can achieve excellent surface smoothness and abrasion resistance, similar to when fine inorganic powder is directly used as a filler. Furthermore, a paste-like dental curable composition with excellent handling properties can be obtained, and the polymerization shrinkage rate can also be reduced.

[0004] In recent years, the growing desire for aesthetics has led to an increasing demand for tooth whitening, which uses peroxide to whiten teeth. This has led to a demand for composite resins with colors suitable for restoring teeth after whitening (also known as whitened teeth). For this reason, CRs that correspond to colors known as bleach shades (or W-type shades), which emphasize whiteness, have also begun to be offered.

[0005] However, the organic-inorganic composite filler itself may have a yellowish tinge due to polymerization or pulverization during its production process, and therefore, in dental curable compositions containing the organic-inorganic composite filler, there are limitations to the ability to adjust the color tone using pigments to meet the aesthetic restoration needs of whitened teeth.

[0006] Therefore, several organic-inorganic composite fillers that can be used for the above-mentioned aesthetic restoration have been proposed. Specifically, Patent Document 3 proposes an organic-inorganic composite filler in which an organic-inorganic composite filler made of a polymer of a polymerizable monomer containing an inorganic filler is decolorized with peroxide. Patent Document 4 also proposes an organic-inorganic composite filler containing a fluorescent brightener that absorbs ultraviolet light and emits purple-blue to blue-green fluorescence near the short wavelength side of the visible light spectrum. Furthermore, an organic-inorganic composite filler is also known that does not include a pulverization step, which can cause coloration, as a manufacturing process, and is produced by impregnating inorganic aggregate particles with a polymerizable monomer and polymerizing and curing the resulting material (see Patent Document 5). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 2000-80013 [Patent Document 2] Patent Publication No. 2008-37952 [Patent Document 3] Japanese Patent Publication No. 10-114616 [Patent Document 4] Patent No. 4993053 [Patent Document 5] International Publication No. 2011 / 115007 Brochure Summary of the Invention [Problem to be solved by the invention]

[0008] However, according to the investigations of the present inventors, it has become clear that even when the organic-inorganic composite fillers disclosed in the above-mentioned Patent Documents 3 to 5 are used, it is difficult to apply them to the aesthetic restoration of whitened teeth whose brightness has been highly improved by treatment with peroxides, etc. That is, it has been found that a cured product of a CR made from a dental curable composition containing an organic-inorganic composite filler and an inorganic filler may have a slight yellowish tinge (even when an organic-inorganic composite filler with a low yellowish tinge is used), and when the appearance is made white with a white pigment, the transparency is significantly reduced, and when an attempt is made to reduce the yellowish tinge with a blue pigment, sufficient whiteness (brightness) cannot be obtained.

[0009] Therefore, an object of the present invention is to provide a dental hardenable composition that contains an organic-inorganic composite filler and an inorganic filler, and that can give a cured product having sufficient whiteness and appropriate transparency, and that can be used as a CR that can be used for the aesthetic restoration of highly whitened teeth. [Means for solving the problem]

[0010] The present invention solves the above problems, and a first aspect of the present invention is A dental curable composition comprising a base composition including 100 parts by mass of a polymerizable monomer (A), 60 to 420 parts by mass of an organic-inorganic composite filler (B) made of a powdery material constituted by particles made of a composite of inorganic particles and a resin, 60 to 420 parts by mass of an inorganic filler (C) made of inorganic powdery material constituted by inorganic particles, and 0.5 to 5.0 parts by mass of a polymerization initiator (D), As the colorant (E), 50 to 1000×10 -6 Parts by mass of white colorant (e1) and 0.01 to 3 x 10 -6 parts by mass of a blue colorant (e2), 60% by mass or more of the inorganic filler (C) is composed of powder particles (c1) having an average primary particle diameter of 350 to 600 nm and composed of spherical particles each having a spherical core made of silica and a silica-based composite oxide coating layer coating the outer surface of the spherical core, For a sample of a certain thickness made of a specific material, based on the tristimulus values ​​X, Y, and Z of the XYZ color system obtained by reflection measurement under geometric condition c of JIS Z8722 5.3.1 using auxiliary illuminant C specified in JIS Z8720, Formula: YI = 100(1.28X - 1.06Z) / Y The yellowness index of the material is defined as YI calculated by the following formula: For a plate-shaped sample made of a specific material and having a thickness of 1 mm, the color tone of the reflected light when irradiated with auxiliary illuminant C on a black background and a white background is measured using a spectrophotometer to obtain tristimulus values ​​of the XYZ color system, respectively. Based on the Y value Yb on the black background and the Y value Yw on the white background, the value calculated as the ratio of the two, Yb / Yw, is defined as the contrast ratio of the material. For a 1 mm thick plate sample made of a specific material, the color tone of the reflected light when irradiated with auxiliary illuminant C on a white background is measured using a spectrophotometer in the CIE Lab color system, L * , a * and b * L obtained by measuring * When the value of is the brightness of the material, The dental curable composition has a yellowness index (YI) of −5.0 to 5.0, a contrast ratio (Yb / Yw) of 0.55 to 0.75, and a lightness (L * gives a hardened body having a hardness of 79 to 85. The dental hardenable composition is characterized by the following:

[0011] In the dental curable composition of the above form (hereinafter also referred to as "dental curable composition of the present invention"), it is preferable that the ratio t / d of the average radius d (nm) of the spherical core particles constituting the powder granule (c1) to the average thickness t (nm) of the silica-based composite oxide coating layer is 0.4 to 0.9.

[0012] It is also preferable that the white colorant (e1) is made of titanium dioxide, and the blue colorant (e2) is made of a blue organic pigment.

[0013] A second aspect of the present invention is a composite resin for bleach shades, characterized by comprising the dental hardenable composition of the present invention.

[0014] A third aspect of the present invention is a method for producing the dental hardenable composition of the present invention, comprising: a mixing step of mixing 100 parts by mass of the polymerizable monomer (A), 60 to 420 parts by mass of the organic-inorganic composite filler (B), 60 to 420 parts by mass of the inorganic filler (C), 0.5 to 5.0 parts by mass of the polymerization initiator (D), and the colorant (E), In the mixing step, the curable composition obtained after the mixing step has a yellowness index: YI of -5.0 to 5.0, a contrast ratio: Yb / Yw of 0.55 to 0.75, and a brightness: L * the blending amounts of the white colorant (e1) and the blue colorant (e2) are adjusted within the above ranges so as to give a cured product having a viscosity of 79 to 85. The present invention relates to a method for producing a dental hardenable composition.

[0015] In the manufacturing method of the above embodiment (hereinafter also referred to as "the manufacturing method of the present invention"), a plurality of hardenable composition samples are prepared by blending a white colorant (e1) and a blue colorant (e2) in different amounts into a plurality of hardenable compositions having the same composition as the base composition of the target dental hardenable composition, and the contrast ratio, the yellowness index (YI) and the brightness (L) of the hardened products of these samples are measured. *and adjusting the amounts of the white colorant (e1) and the blue colorant (e2) based on the correlation between the measurement result and the amounts of these colorants.

[0016] Furthermore, with regard to the organic-inorganic composite filler (B), it is preferable that a paste composition obtained by mixing 60 parts by mass of the organic-inorganic composite filler (B) with 40 parts by mass of a standard monomer composition consisting of 70% by mass of 2,2-bis[4-(methacryloyloxyethyl)phenyl]propane (hereinafter sometimes abbreviated as "D-2.6E") and 30% by mass of triethylene glycol dimethacrylate is subjected to measurement of the yellowness index (YI) so that the paste composition has a constant thickness, and that the organic-inorganic composite filler (B) whose YI is confirmed to be within the range of 0 to 25 is used in the mixing step. [Effects of the Invention]

[0017] According to the present invention, it is possible to obtain a paste that has good workability and little polymerization shrinkage, as well as excellent abrasion resistance and aesthetics, and a hardened product that is white and suitable for whitening tooth restoration and has appropriate transparency and brightness. DETAILED DESCRIPTION OF THE INVENTION

[0018] The dental curable composition of the present invention contains (A) a polymerizable monomer, (B) an organic-inorganic composite filler consisting of a powdery material composed of particles that are a composite of inorganic particles and a resin, (C) an inorganic filler consisting of inorganic particles, (D) a polymerization initiator, and (E) a colorant.

[0019] The greatest feature of the present invention is that in a dental curable composition containing (B) an organic-inorganic composite filler and (C) an inorganic filler, in order to obtain a composite resin with a color tone suitable for whitening tooth restoration, 60 mass % or more of the (C) inorganic filler is a powder or granule having an average primary particle diameter of 350 to 600 nm and composed of spherical particles having a spherical core made of silica and a silica-based composite oxide coating layer covering the outer surface of the spherical core, thereby reducing the yellowness of the cured product of the base composition not containing the (E) colorant to a yellowness index of 10 or less.

[0020] Increasing the amount of white pigment added to counteract the yellowness derived from the resin component reduces the transparency of the cured product, as described above, and thus reduces aesthetic appeal. On the other hand, adding a blue pigment reduces the yellowness, but because coloring using a pigment relies on the absorption of light of a specific wavelength, the brightness of the composition decreases. In contrast, in the dental curable composition of the present invention, the yellowness derived from the resin component itself is reduced as described above, so the yellowness derived from the resin component can be reduced without particularly increasing the amounts of white pigment and blue pigment added. Therefore, it is possible to achieve a color tone suitable for whitening tooth restoration without reducing the transparency or brightness of the cured product.

[0021] The reason why the yellowness of the dental curable composition is reduced when silica-based composite oxide particles having a spherical core made of silica are used is not entirely clear, but the present inventors believe it to be as follows: When a silica core is present, the refractive index of the silica core differs from that of the composite oxide layer covering it, so the silica core is recognized as a fine particle in the composition, and so the incident light undergoes so-called Rayleigh scattering, scattering blue light within the incident light, making the composition appear bluish, and reducing the yellowness derived from the resin component.

[0022] The dental curable composition of the present invention comprises a base composition comprising 100 parts by mass of a polymerizable monomer (A), 60 to 420 parts by mass of an organic-inorganic composite filler (B) made of powder particles constituted by particles of a composite of inorganic particles and a resin, 60 to 420 parts by mass of an inorganic filler (C) made of inorganic powder particles constituted by inorganic particles, and 0.5 to 5.0 parts by mass of a polymerization initiator (D), and a colorant (E) in an amount of 50 to 1000×10 per part by mass of the base composition. -6 Parts by mass of white colorant (e1) and 0.01 to 3 x 10 -6 By further blending parts by mass of a blue-based colorant (e2) and making 60 mass % or more of the inorganic filler (C) into powder (c1) composed of spherical particles having a silica core and a silica-based composite oxide coating layer coating the outer surface of the spherical core, and having an average primary particle diameter of 350 to 600 nm, it is possible to obtain a composition having a yellowness index (YI) of -5.0 to 5.0, a contrast ratio (Yb / Yw) of 0.55 to 0.75, and a brightness (L * The hardened body has a viscosity of 79 to 85.

[0023] Here, yellowness: YI, contrast ratio: Yb / Yw, and brightness: L * are calculated as follows, respectively:

[0024] That is, the yellowness index (YI) is an index that indicates the degree to which the hue of a material deviates from colorless or white toward yellow, and is usually a positive value, with a negative value indicating that the hue is bluish. In the present invention, the yellowness index (YI) is calculated based on the tristimulus values ​​X, Y, and Z of the XYZ color system obtained by reflection measurement of a sample having a certain thickness (preferably 0.5 to 5 mm, particularly preferably 1 to 3 mm) using auxiliary illuminant C specified in JIS Z8720 under geometric condition c of JIS Z8722, Formula: YI = 100(1.28X - 1.06Z) / Y It can be calculated by:

[0025] The contrast ratio Yb / Yw is an index of transparency, with the closer to 0 the higher the transparency and the closer to 1 the lower the transparency. In the present invention, the contrast ratio can be determined as the ratio Yb / Yw of the Y value for the black background and Yb for the white background, obtained by measuring the color tone of the reflected light when irradiating a 1 mm thick plate-shaped sample with auxiliary illuminant C against a black background and a white background using a spectrophotometer to measure the tristimulus values ​​of the XYZ color system.

[0026] Furthermore, lightness is an index showing the brightness of a color, and the closer it is to 0, the closer it is to completely black, and the closer it is to 100, the closer it is to completely white. In the present invention, the lightness is measured by measuring the color tone of the reflected light when a 1 mm thick plate sample is irradiated with auxiliary illuminant C against a white background using a spectrophotometer, in the CIE Lab color system, L * , a * and b * L obtained by measuring * It is calculated as the value of

[0027] The dental curable composition of the present invention has a yellowness index (YI) of −5.0 to 5.0, a contrast ratio (Yb / Yw) of 0.55 to 0.75, and a lightness (L * It is preferable to obtain a cured product having a yellowness index (YI) of 79 to 85, a contrast ratio (Yb / Yw) of 0.60 to 0.70, and a brightness (L * It is more preferable to provide a cured product having a viscosity of 81 to 85.

[0028] In the dental curable composition of the present invention, even if it has the basic composition described above, the above three physical property values ​​of the cured product are affected by the proportion of (c1) in the used (C), the specific amount of (C), the coloring degree and specific amount of the used (B), and the specific amounts of the pigments (e1) and (e2) actually used. Therefore, it is substantially impossible to specify a specific composition such that the above three physical property values ​​satisfy the above conditions. Therefore, the dental curable composition of the present invention is specified by the physical property values ​​of the cured product.

[0029] Each component constituting the dental curable composition of the present invention and a method for producing the dental curable composition of the present invention are described in detail below. In this specification, unless otherwise specified, the expression "x to y" using the numerical values ​​x and y means "greater than or equal to x and less than or equal to y." In such an expression, when a unit is assigned only to the numerical value y, the unit also applies 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."

[0030] 1. Polymerizable Monomer (A) As the polymerizable monomer (A), any polymerizable monomer (monomer) such as a radical polymerizable monomer or a cation polymerizable monomer used in conventional dental curable compositions can be used without any particular limitation. Among them, it is preferable to use a commonly used (meth)acrylate polymerizable monomer, specifically an acidic group-containing (meth)acrylate polymerizable monomer, a hydroxyl group-containing (meth)acrylate polymerizable monomer, or a monofunctional or polyfunctional (meth)acrylate polymerizable monomer not having these substituents.

[0031] Examples of suitable (meth)acrylate polymerizable monomers include the following: Acidic group-containing (meth)acrylate polymerizable monomers: (meth)acrylic acid, N-(meth)acryloyl-p-aminobenzoic acid, 2-(meth)acryloyloxybenzoic acid, 2-(meth)acryloyloxyethyl phenylhydrogen phosphate, 2-(meth)acryloyloxyethyl phosphonic acid, etc. Hydroxyl group-containing (meth)acrylate polymerizable monomers: 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 2,2-bis[(3-methacryloyloxy-2-hydroxypropyloxy)phenyl]propane, 2,2-bis(4-methacryloyloxypolyethoxyphenyl)propane, 2,2-bis[4-(3-methacryloyloxy)-2-hydroxypropoxyphenyl]propane, 2,2-bis[4-(4-methacryloyloxy)-3-hydroxybutoxyphenyl]propane, and the like.

[0032] Monofunctional and polyfunctional (meth)acrylate polymerizable monomers not having the above-mentioned substituents: methyl (meth)acrylate, ethyl (meth)acrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,6-bis(methacrylethyloxycarbonylamino)trimethylhexane, etc.

[0033] A plurality of types of these (meth)acrylate polymerizable monomers may be used in combination as necessary. From the viewpoint of providing a paste state before hardening with suitable shapability and suppressing roughness, it is preferable to use the polyfunctional (meth)acrylate polymerizable monomer having no substituent group as necessary in combination with the monofunctional (meth)acrylate monomer having no substituent group or a hydroxyl group-containing (meth)acrylate polymerizable monomer.

[0034] 2. Organic-inorganic composite filler (B) The dental curable composition of the present invention contains 60 to 420 parts by mass of an organic / inorganic composite filler (B) composed of powder particles formed from a composite of inorganic particles and a resin, per 100 parts by mass of the polymerizable monomer (A). If the content of the organic / inorganic composite filler (B) is less than 60 parts by mass, the paste becomes sticky and its workability decreases. If the content exceeds 420 parts by mass, the paste becomes too yellow due to the organic / inorganic composite powder and becomes unsuitable for white tooth restoration. To achieve both good workability and a color tone suitable for whitening tooth restoration, the content of the organic / inorganic composite filler (B) is preferably 150 to 350 parts by mass, more preferably 150 to 300 parts by mass. The proportion of the organic / inorganic composite filler (B) in the dental curable composition of the present invention, based on the total amount of the organic / inorganic composite filler (B) and the inorganic filler (C) described below, is preferably 30 to 80% by mass, more preferably 50 to 70% by mass.

[0035] The organic-inorganic composite filler (B) can be any of the organic-inorganic composite fillers used in conventional dental curable compositions, and is not particularly limited. From the viewpoint of the ease of use of the dental curable composition (paste) of the present invention and the mechanical strength of the cured product obtained by curing the dental curable composition of the present invention, it is preferable to use one having an average particle size of 2 to 100 μm, particularly 5 to 20 μm. Here, the average particle size refers to the average primary particle size determined by image analysis using a scanning electron microscope (SEM). Based on an image (or photograph) obtained by observing a powder sample with an SEM at a magnification of 5,000 to 100,000 times so that 100 or more spherical particles whose overall shape can be confirmed are included in the field of view, the maximum diameter (nm) of each of 30 or more, preferably 100 or more, arbitrarily selected particles is measured, and the sum is divided by the number: n (a natural number ≧30). That is, the maximum diameter of each particle is expressed as x i (i is a natural number from 1 to n), and the average particle size is x AV When expressed as x AV =(Σx i ) / n.

[0036] The average content of inorganic particles in the constituent particles (organic-inorganic composite particles) of the organic-inorganic composite filler (B) is preferably 60 to 90 mass %, particularly preferably 75 to 90 mass %.

[0037] From the viewpoint of ease of production, it is preferable to use a filler produced by the following production method. That is, it is preferable to use a pulverized organic-inorganic composite filler obtained by blending predetermined amounts of the inorganic powder and granules (hereinafter also referred to as the composite filler raw material inorganic filler), the polymerizable monomer (hereinafter also referred to as the composite filler raw material monomer) that is the raw material for the composite resin component, and a polymerization initiator in a mixer or the like, polymerizing the mixture by heating or light irradiation, and then pulverizing the mixture. In this case, a vibrating ball mill, a jet mill, or the like can be suitably used as the pulverizing method. Furthermore, a composite filler with the desired particle size distribution can be obtained by performing a classification process using a sieve, an air classifier, or water classification, etc.

[0038] It is also preferable to use an organic-inorganic composite filler produced by the method described in Patent Document 5. Specifically, a composite filler raw material inorganic filler is granulated (primary particles are aggregated to form aggregated particles) to have the average particle size described above, then immersed in a solution containing a composite filler raw material monomer, a polymerization initiator, and an organic solvent, and the organic solvent is removed. The composite filler raw material monomer absorbed into the aggregated particles is polymerized and cured by heating, light irradiation, or other methods. This produces a microporous organic-inorganic composite filler (also referred to as an aggregated organic-inorganic filler). The microporous organic-inorganic composite filler has an organic resin layer that covers the surface of each inorganic primary particle and bonds the inorganic primary particles to each other, and the organic resin layer that covers the surface of each inorganic primary particle forms an aggregated particle. From the viewpoint of ease of obtaining the dental curable composition of the present invention, which has little coloring (low yellowness) and a reduced yellowness of the cured product (which satisfies the specified conditions), it is more preferable to use an aggregated filler that does not require a grinding process.

[0039] The material of the inorganic filler raw material for the composite filler is not particularly limited, and inorganic compounds such as inorganic oxides, such as amorphous silica, silica zirconia, silica titania, barium silica titania, quartz, and alumina, can be used. As the inorganic filler material, composite oxides primarily composed of silica and zirconia are particularly preferred, as they produce a cured product with X-ray contrast. The inorganic filler raw material for the composite filler is surface-treated with a silane coupling agent or the like before use, as necessary. The average primary particle diameter of the inorganic filler raw material for the composite filler is preferably 20 to 1,000 nm, more preferably 20 to 300 nm. The average primary particle diameter is synonymous with the average primary particle diameter in (c1) described below.

[0040] As the composite filler raw material monomer, the monomers exemplified as the polymerizable monomer (A) can be suitably used, although it is not necessary to use the same one as the polymerizable monomer (A).

[0041] The polymerization initiator used in the production of the organic-inorganic composite filler may be any known polymerization initiator without any particular restrictions. However, it is preferable to use a thermal polymerization initiator, since it is possible to obtain a cured product with a lower yellowness, and it is even more preferable to use a compound that does not have an aromatic ring in its structure.

[0042] As described above, it is preferable to use an organic-inorganic composite filler (B) that is less colored by itself (low yellowness index). For this reason, it is preferable to use an organic-inorganic composite filler (B) that has been confirmed to have a YI of 0 to 25, particularly 0 to 15, by measuring the yellowness index (YI) of a paste composition prepared by the following method so that the paste composition has a constant thickness.

[0043] Here, the paste-like composition refers to a paste-like composition prepared by kneading 60 parts by mass of organic-inorganic composite filler (B) with 40 parts by mass of a standard monomer composition consisting of 70% by mass of 2,2-bis[4-(methacryloyloxyethyl)phenyl]propane ("D-2.6E") and 30% by mass of triethylene glycol dimethacrylate. YI can be determined by preparing a mold with a hole of a predetermined thickness (for example, a predetermined thickness within a range of 1 to 3 mm), sealing the bottom of the hole with a polypropylene film, introducing the paste-like composition into the hole, and then placing a polypropylene film on the top of the hole and pressing it against the top. This is used as a measurement sample, and the tristimulus values ​​(X, Y, and Z) are measured according to the method described above.

[0044] 3. Inorganic filler (C) The dental curable composition of the present invention contains 60 to 420 parts by mass of inorganic filler (C) composed of inorganic powder and granules formed from inorganic particles per 100 parts by mass of polymerizable monomer (A). If the content of inorganic filler (C) is less than 60 parts by mass, the effect of reducing yellowness becomes insufficient, while if it exceeds 420 parts by mass, the paste becomes thicker, resulting in poor operability such as stickiness. To reduce the yellowness of the paste while maintaining good paste operability, the content of inorganic filler (C) is preferably 150 to 310 parts by mass, more preferably 150 to 250 parts by mass. The inorganic powder and granules that constitute the inorganic filler (C) are surface-treated with a silane coupling agent or the like, as necessary, before use.

[0045] Furthermore, in the dental curable composition of the present invention, at least 60% by mass of the inorganic filler (C) to be blended must be powder (c1) composed of spherical particles having a silica core and a silica-based composite oxide coating layer covering the outer surface of the spherical core, and having an average primary particle diameter of 350 to 600 nm. If the content of (c1) is less than 60% by mass, the effect of reducing yellowness will be insufficient. To obtain the effect of reducing yellowness while reducing polymerization shrinkage and imparting sufficient mechanical strength to the cured product, the content of (c1) is preferably 60 to 90% by mass, and more preferably 60 to 80% by mass.

[0046] When the content of (c1) in (C) is less than 100% by mass, the other inorganic powder particles contained therein are not particularly limited. In order to obtain a dental curable composition that gives a cured product excellent in abrasion resistance and surface gloss and that is excellent in operability, the other inorganic powder particles preferably include inorganic powder particles (c2) made of spherical silica-based composite oxide particles having an average primary particle diameter of 1 to 1,000 nm and no core layer consisting solely of silica inside the particles.

[0047] The following will explain the above-mentioned powder particles (c1) and (c2) that are constituents of the inorganic filler, as well as the powder particle (c3) that may be contained in addition to these.

[0048] (3-1) Inorganic powder (c1) The powder (c1) constituting 60% by mass or more of the inorganic filler (C) is a powder having an average primary particle diameter of 350 to 600 nm, which is composed of spherical particles having a spherical core made of silica and a silica-based composite oxide coating layer covering the outer surface of the spherical core.

[0049] Here, the spherical shape may be approximately spherical, but does not necessarily have to be a perfect sphere. Generally, particles are photographed with a scanning electron microscope (SEM), and for each particle (30 or more) within a unit field of view, the average uniformity obtained by dividing the particle diameter in the direction perpendicular to the maximum diameter by the maximum diameter is 0.6 or more, more preferably 0.8 or more.

[0050] The average primary particle diameter means the average particle diameter determined by image analysis using a scanning electron microscope (SEM) image, and is calculated by measuring the maximum diameter (nm) of at least 30 arbitrarily selected particles based on the image (or photograph) obtained when observing a powder sample with an SEM at a magnification of 5,000 to 100,000 times so that at least 100 spherical particles whose overall shape can be confirmed are included in the field of view, and then dividing the sum by the number: n (a natural number ≧30). In other words, the maximum diameter of each particle is expressed as x i (i is a natural number from 1 to n), and the average particle size is x AV When expressed as x AV =(Σx i ) / n. Here, commercially available image analysis software may be used to measure the maximum diameter (nm) of each particle. It is known that spherical particles obtained by the so-called sol-gel method described below have a uniform particle size, with extremely large or extremely small particles being almost absent, and this is also true in the production method of the present invention, so the average particle size determined by the above method can be said to represent the overall average particle size.

[0051] Examples of silica-based composite oxides constituting the silica-based composite oxide coating layer include silica-zirconia, silica-titania, silica-titania-barium oxide, and silica-titania-zirconia. Among these, silica-zirconia and silica-titania are preferred because they can impart favorable X-ray opacity when incorporated into a dental composition and also have a favorable refractive index as a filler for incorporation into a dental composition. Furthermore, these silica-based composite oxides preferably contain a trace amount of sodium in addition to major metals such as zirconium and titanium.

[0052] The powder (c1) can be suitably produced by the so-called sol-gel method, as described in Japanese Patent Publication No. 1-38044. Specifically, the powder (c1) is suitably produced by adding only a silica raw material compound such as tetraalkoxysilane to a basic solution, carrying out hydrolysis and dehydration condensation to form a silica core, and then adding a mixture of the silica raw material compound and a metal oxide raw material compound such as an alkoxide of a metal that forms a composite oxide with silicon, carrying out hydrolysis and dehydration condensation to grow a composite oxide layer around the silica core.

[0053] In this production method, the particle size of the silica core particles can be increased by increasing the amount of silica raw material compound added during synthesis. The thickness of the silica-based composite oxide coating layer that covers the outer surface of the silica core can be increased by extending the time for adding the mixture of silica raw material compound and metal oxide raw material compound to the silica core. Therefore, by controlling these conditions, the average primary particle size, silica core particle size, and the thickness of the silica-based composite oxide coating layer can be controlled.

[0054] In the powder (c1), the ratio t / d of the average radius d (nm) of the spherical core particles constituting the powder (c1) to the average thickness t (nm) of the silica-based composite oxide coating layer is preferably 0.4 to 0.9, particularly 0.4 to 0.7.

[0055] (3-2) Inorganic powder (c2) The inorganic powder (c2) is composed of spherical silica-based composite oxide particles having an average primary particle diameter of 1 to 1000 nm, preferably 5 to 200 nm, which do not have a core layer made of silica alone inside the particle.

[0056] Examples of silica-based composite oxides that form the constituent particles of the inorganic powder (c2) include silica-zirconia, silica-titania, silica-titania-barium oxide, and silica-titania-zirconia. Of these, silica-zirconia and silica-titania are preferred because they can impart favorable X-ray opacity when incorporated into a dental composition and also provide a favorable refractive index for use as a filler in a dental composition. Furthermore, these silica-based composite oxides preferably contain a trace amount of sodium in addition to major metals such as zirconium and titanium.

[0057] The inorganic powder and particle (c2) can be suitably produced by omitting the silica core formation step in the sol-gel method described as the production method (c1), and adding a mixture of a metal oxide raw material compound and carrying out hydrolysis and dehydration condensation.

[0058] (3-3) Inorganic powder (c3) The inorganic powder (c3) may be any inorganic powder other than the inorganic powders (c1) and (c2) that can be used as an inorganic filler in a dental curable composition, without any particular limitation. Suitable examples include metal oxides such as amorphous silica, quartz, alumina, titania, zirconia, barium oxide, yttrium oxide, lanthanum oxide, and ytterbium oxide; silica-based composite oxides such as silica-zirconia, silica-titania, silica-titania-barium oxide, and silica-titania-zirconia; glass such as borosilicate glass, aluminosilicate glass, and fluoroaluminosilicate glass; metal fluorides such as barium fluoride, strontium fluoride, yttrium fluoride, lanthanum fluoride, and ytterbium fluoride; inorganic carbonates such as calcium carbonate, magnesium carbonate, strontium carbonate, and barium carbonate; and metal sulfates such as magnesium sulfate and barium sulfate.

[0059] 4. Polymerization initiator (D) The polymerization initiator (D) is not particularly limited as long as it has the function of polymerizing the polymerizable monomer (A). However, it is preferable to use a photopolymerization initiator or a chemical polymerization initiator that is used in direct dental filling and restoration applications, which are often cured in the oral cavity, and it is even more preferable to use a photopolymerization initiator (composition) from the viewpoint of simplicity, as it does not require a mixing operation.

[0060] Any known chemical polymerization initiator consisting of two or more components that generates polymerization initiating species (radicals) when the components are brought into contact can be used without limitation. Examples include those consisting of various combinations such as organic peroxide / amines, organic peroxide / amines / organic sulfinic acids, organic peroxide / amines / aryl borates, aryl borates / acidic compounds, and barbituric acid derivatives / copper compounds / halogen compounds. Of these, those consisting of organic peroxide / amines are particularly preferred because of their ease of handling.

[0061] As the organic peroxide, known hydroperoxides, peroxyketals, ketone peroxides, alkylsilyl peroxides, diacyl peroxides, peroxyesters, etc. can be used.

[0062] In addition, photopolymerization initiators that can be used include benzoin alkyl ethers, benzil ketals, benzophenones, α-diketones, thioxanthone compounds, and bisacylphosphine oxides. These photopolymerization initiators may also contain reducing agents such as tertiary amines, aldehydes, and sulfur-containing compounds. Furthermore, photoacid generators such as diaryliodonium salt compounds, sulfonium salt compounds, sulfonic acid ester compounds, halomethyl-substituted S-triazine derivatives, and pyridinium salt compounds may also be added.

[0063] These polymerization initiators may be used alone or in combination of two or more. The most preferred combination is camphorquinone / photoacid generator / aromatic amine / aliphatic amine, because coloration can be reduced by reducing the amount of α-diketones, which are photosensitizers that absorb light in the visible light range and cause coloration.

[0064] The amount of the polymerization initiator (D) to be blended is 0.5 to 5.0 parts by mass, and more preferably 0.5 to 2.0 parts by mass, based on 100 parts by mass of the polymerizable monomer (A).

[0065] 5. Colorant (E) The dental curable composition of the present invention is a base composition comprising 100 parts by mass of a polymerizable monomer (A), 60 to 420 parts by mass of an organic-inorganic composite filler (B) made of powder particles formed of particles composed of a composite of inorganic particles and a resin, 60 to 420 parts by mass of an inorganic filler (C) made of inorganic powder particles formed of inorganic particles, and 0.5 to 5.0 parts by mass of a polymerization initiator (D), with a ratio of 50 to 1000×10 -6 Parts by mass of white colorant (e1) and 0.01 to 3 x 10 -6 Parts by weight of a blue colorant (e2) are further included.

[0066] By blending the white and blue colorants in amounts within the above ranges, the yellowness index (YI) of the cured product of the dental curable composition can be set to -5.0 to 5.0, the contrast ratio (Yb / Yw) can be set to 0.55 to 0.75, and the brightness (L * can be set to 79 to 85.

[0067] The coloring agent used may be a pigment or a dye, but in consideration of color stability in the oral cavity, it is preferable to use a water-insoluble pigment rather than a water-soluble dye.

[0068] When a pigment is used as a colorant, the pigment can be added to the formulation in the form of a dispersion to facilitate mixing with other components of the dental filling and restorative material. For example, the pigment can be used as a masterbatch in which the pigment is dispersed in a low-viscosity liquid such as a reactive diluent or in a powder such as inorganic particles.

[0069] As the white pigment, titanium oxide, zinc oxide, zirconium oxide, or the like can be used, but titanium oxide is particularly preferred. The amount of the white pigment added is 50 to 700×10 based on 1 part by mass of the base composition. -6 Parts by weight parts by weight is more preferred.

[0070] As the blue pigment, blue pigments such as cobalt blue, ultramarine, Prussian blue, chromophtal blue, pigment blue, phthalocyanine blue, etc., and blue dyes such as KAYASET Blue N, KAYASET Blue G, and KAYASET Blue B can be used, but it is particularly preferable to use pigment blue. The amount of blue pigment added is 0.01 to 1 × 10 per 1 part by mass of the base composition. -6 Parts by mass are more preferred.

[0071] The dental hardenable composition of the present invention can also contain other yellow or red colorants as needed, as long as the effects of the present invention are not impaired. Red pigments such as Pigment Red and red dyes such as KAYASET RED G can be used without particular restrictions as red colorants, and yellow pigments such as Pigment Yellow and yellow dyes such as KAYASET Yellow 2G can be used without particular restrictions as yellow colorants. By combining multiple of these colorants and adjusting the respective amounts, the color tone of the hardened product of each hardenable paste can be adjusted.

[0072] The total amount of the colorant (E) to be blended is 50 to 1500×10 relative to 1 part by mass of the base composition. -6 Parts by mass are preferably 50 to 1000 × 10 -6 parts by mass, more preferably 50 to 600 × 10-6 It is particularly preferred that the amount is parts by weight.

[0073] 6. Other optional ingredients The dental curable composition of the present invention may contain additives such as polymerization inhibitors, ultraviolet absorbers, thickeners, etc., as needed, within the range that does not impair the effects of the present invention.

[0074] 7. Uses of the dental hardenable composition of the present invention The dental curable composition of the present invention has the above-mentioned yellowness index: YI, contrast ratio: Yb / Yw and lightness: L * Therefore, it can be suitably used as a CR corresponding to the color tone of so-called bleach shade or W-type shade, which is a composite resin for whitening tooth restoration.

[0075] 8. Manufacturing method of the present invention The dental curable composition of the present invention is characterized in that, in a mixing step of mixing 100 parts by mass of the polymerizable monomer (A), 60 to 420 parts by mass of the organic-inorganic composite filler (B), 60 to 420 parts by mass of the inorganic filler (C), 0.5 to 5.0 parts by mass of the polymerization initiator (D), and the colorant (E), the curable composition obtained after the mixing step has a yellowness index: YI of −5.0 to 5.0, a contrast ratio: Yb / Yw of 0.55 to 0.75, and a lightness: L * The amount of the white colorant (e1) and the blue colorant (e2) blended is adjusted so as to give a cured product having a viscosity of 79 to 85, thereby making it possible to suitably produce the composition.

[0076] In the mixing step, first, the required amounts of components (A) to (D) are weighed out and mixed in a dark place to prepare a paste. The methods for weighing and mixing the components are not particularly limited, but it is preferable to use a kneading device such as a planetary stirrer because this allows the curable composition of the present invention to be uniformly mixed in a short time and facilitates scale-up production.

[0077] Next, a colorant (E) is added to the obtained paste to perform color matching. To uniformly disperse the colorant in the curable composition, the colorant is added and then mixed using the mixing device used in the mixing step. At this time, the colorant (E) is blended with a white colorant (e1) and a blue colorant (e2) within the ranges described above. During blending, multiple curable composition samples were prepared by blending different amounts of the white colorant (e1) and the blue colorant (e2) into multiple curable compositions having the same composition as the base composition of the target dental curable composition. The contrast ratio, yellowness index (YI), and brightness index (L) were measured for the cured products of these multiple samples. * and adjusting the amounts of the white colorant (e1) and the blue colorant (e2) based on the correlation between the measurement result and the amounts of these colorants.

[0078] The correlation between the blending amounts of the above colorants is as follows: Specifically, without adding the blue colorant (e2), only the white colorant (e1) is blended in varying amounts, and the blending amount of the white colorant and the brightness: * By grasping the correlation with the white colorant, the desired amount of white colorant can be determined. * After fixing the blending amount to obtain a brightness close to the desired value, the blending amount of the blue colorant is varied and blended to grasp the correlation with the yellowness: YI, and the blending amount of the blue colorant that obtains a yellowness close to the desired YI value is determined. Finally, the blending amounts of the white colorant and blue colorant are finely adjusted to obtain a brightness: L * It is preferable to determine the blending amount so that both the color and yellowness index (YI) fall within the desired range.

[0079] As described above, it is preferable to use the organic-inorganic composite filler (B) in the mixing step by measuring the YI of a paste composition obtained by mixing the organic-inorganic composite filler (B) with a standard monomer composition and confirming that the YI is within the range of 0 to 25. [Example]

[0080] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0081] 1. Production and evaluation of inorganic fillers Inorganic fillers F-1 to F-4 used in the examples and comparative examples were produced by the following Production Examples 1 to 4. F-1 and F-2 are inorganic fillers made of spherical silica-based composite oxide particles (core-shell type) produced by growing a silica-zirconia composite oxide layer on a core made of silica alone, while F-3 and F-4 are fillers made of spherical silica-based composite metal oxide particles (non-core-shell type) that do not have the silica core. In each Production Example, the raw materials used are represented by abbreviations, and the relationship between the raw materials and abbreviations is as follows:

[0082] <Condensed silica component raw material compound> (also called silicon oxide raw material) TES: Tetraethyl silicate <Condensed metal oxide raw material compound> (also called metal oxide raw material) TBZ: Tetra(n-butoxy)zirconate ·NaOMe: Sodium methoxide KOMe: Potassium methoxide <(Water-soluble) organic solvent> MeOH: Methanol IPA: 2-propanol · IBA: 2-methyl-1-propanol.

[0083] Production Example 1: Production of silica-zirconia composite oxide filler F-1 having a silica core and an average particle size of about 400 nm 10 g of 0.05% by mass hydrochloric acid water and 270 g of TES (manufactured by Colcoat Co., Ltd.) were dissolved in 400 g of methanol (MeOH) and mixed for 4 hours at 40°C to hydrolyze, thereby preparing a silica component raw material composition. Separately, 80 g of TBZ (manufactured by Nippon Soda Co., Ltd.) and 50 g of IBA were mixed to prepare metal oxide component raw material composition 1. Metal oxide component raw material composition 1 was then added to the silica component raw material composition and stirred for 10 minutes. 9 g of the methanol solution containing 28% by mass of NaOMe was then added to the resulting mixed solution while stirring, thereby obtaining a raw material solution. Next, a 3-L glass reactor equipped with a stirrer was filled with 700 g of IBA and 100 g of IPA, and 320 g of 25% by mass aqueous ammonia was added to prepare an ammoniacal alcohol solution. While maintaining the temperature of the reactor at 45°C, 30 g of TES was added and stirred for 30 minutes to form silica core particles in the reactor. The previously prepared raw material solution was added to the solution over 6 hours while maintaining the temperature of the reactor at 45°C. After the addition was completed, stirring was continued for 30 minutes to obtain spherical silica composite oxide particles. The particles were then collected by suction filtration and dried under reduced pressure at 80°C to obtain a white powder. The powder was calcined at 800°C for 4 hours to produce inorganic filler: F-1.

[0084] The average primary particle size of the silica core particles: D = 2d, the average primary particle size of F-1: D', and the thickness of the coating layer were determined for the obtained F-1 using the measurement methods described below. The average primary particle size of the silica core particles: D = 232 nm (average radius d = 116 nm), the average primary particle size of F-1: D' = 422 nm, the average thickness of the silica-based composite oxide (silica-zirconia) coating layer: t was 95 nm, and the value of t / d was 0.82.

[0085] <Method for measuring average primary particle size> In the SEM (magnification: 50,000 times) photograph of the powder sample F-1, image processing was performed using image analysis software ("IP-1000PC", manufactured by Asahi Kasei Engineering Co., Ltd.), and the maximum diameter of each of 30 or more particles randomly selected from among 100 or more spherical particles whose overall shape could be confirmed within the field of view: x i(i is a natural number from 1 to n) (nm) are measured and the sum is: Σx i The average primary particle size was calculated by dividing by the number of measured particles: n (a natural number of 30 or more).

[0086] <Method for measuring the thickness of the coating layer> Silica core particles prepared in the same manner as in Production Example 1 were collected by suction filtration (as is, without adding the raw material solution), and then dried and fired in the same manner as in Production Example 1 to obtain a powder granule from the obtained spherical silica particles. The average primary particle diameter: D of the powder granule was determined in the same manner as above, and half of the difference (DD') between this and the average primary particle diameter: D' of F-1 was calculated as the average thickness: t of the coating layer of F-1.

[0087] Production Example 2: Production of silica-zirconia composite oxide filler F-2 having a silica core and an average particle size of 600 nm Inorganic filler F-2 was produced in the same manner as in Production Example 1, except that the amount of TES added to the ammoniacal alcohol solution was changed to 40 g and the time for adding the raw material solution was changed to 8 hours. The D, D', t, and t / d of the obtained F-2 were determined in the same manner as in Production Example 1, and the results were D = 360 nm (d = 180 nm), D' = 600 nm, t = 120 nm, and t / d = 0.67.

[0088] Production Example 3: Production of spherical silica zirconia filler F-3 having an average particle size of 150 nm and no silica core 80 g of TES (manufactured by Colcoat Co., Ltd.) was mixed with 400 g of IBA, and 5 g of 0.05% aqueous sulfuric acid was added. Hydrolysis was carried out at 40°C for approximately 1 hour with stirring. This solution was then mixed with 35 g of TBZ (manufactured by Nippon Soda Co., Ltd.) and a solution of NaOMe methanol solution (28% by mass concentration) dissolved in 200 g of IBA while stirring to prepare a TES and TBZ mixed solution. Next, 4 g of TES was added to an ammoniacal alcohol solution containing 1000 g of methanol and 250 g of 25% aqueous ammonia in a 3 L glass vessel equipped with a stirrer while stirring. After stirring for 30 minutes, the TES and TBZ mixed solution was added dropwise over approximately 6 hours. The temperature of the reaction vessel was maintained at 40°C during the reaction. After the reaction was complete, the solvent was distilled off from the cloudy reaction vessel liquid, dried, and calcined at 950°C for 1 hour to obtain a powder of spherical silica-zirconia particles, which was then surface-treated with γ-methacryloyloxypropylmethoxysilane to obtain inorganic filler F-3. The average primary particle diameter: D of the obtained F-3 was measured in the same manner as in Production Example 1 and was found to be 150 nm.

[0089] Production Example 4: Production of spherical silica-titania filler F-4 having an average particle size of 60 nm and no silica core 80 g of TES (manufactured by Colcoat Co., Ltd.) was mixed with 200 g of methanol, and 2.5 g of 0.04% aqueous hydrochloric acid was added. The mixture was hydrolyzed at 30°C for approximately 1 hour with stirring. This solution was then mixed with 10 g of TBZ (manufactured by Nippon Soda Co., Ltd.) and a solution of 5 g of KOMe methanol solution (30% by mass concentration) dissolved in 100 g of IPA while stirring to prepare a mixed solution of TES and tetrabutyl titanate. Next, the mixed solution was added dropwise over approximately 5 hours with stirring to an ammoniacal alcohol solution containing 1000 g of methanol and 250 g of 25% aqueous ammonia in a 10 L glass vessel equipped with a stirrer. The temperature of the reaction vessel was maintained at 40°C throughout the reaction. After completion of the reaction, the solvent was removed from the cloudy reaction vessel liquid by distillation, and the resulting mixture was dried and calcined at 950°C for 1 hour to obtain a powder consisting of silica-titania particles. This powder was then surface-treated with γ-methacryloyloxypropylmethoxysilane to obtain inorganic filler F-4. The average primary particle diameter: D of the obtained F-4 was measured in the same manner as in Production Example 1, and was found to be 160 nm.

[0090] Table 1 shows the compositions of inorganic fillers F-1 to F-4 and the measurement results of the average primary particle diameter and the like.

[0091] [Table 1]

[0092] 2. Production and evaluation of organic-inorganic composite fillers Organic-inorganic composite fillers CF-1 and CF-2 used in the examples and comparative examples were produced by the following Production Examples 5 and 6. In each Production Example, the raw materials used are represented by abbreviations, and the relationship between the raw materials and the abbreviations is as follows:

[0093] <Polymerizable monomer> UDMA: 1,6-bis(methacrylethyloxycarbonylamino)trimethylhexane 3G: Triethylene glycol dimethacrylate D-2.6E: 2,2-bis[4-(methacryloyloxyethyl)phenyl]propane <Polymerization initiator> BPO: Benzoyl peroxide ·AIBN: Azobisisobutyronitrile.

[0094] Production Example 5 Production of CF-1 First, a matrix monomer composition was prepared by dissolving 0.5% BPO by mass in a mixture of UDMA and 3G (UDMA / 3G mass ratio = 80 / 20). Next, 10 g of the matrix monomer composition was added to and mixed with 30 g of the inorganic filler (F-3) obtained in Production Example 3 in a mortar to form a paste. The resulting paste was polymerized at 95°C in a N2 atmosphere for 1 hour, and the resulting polymer was crushed using a roll crusher and then crushed for 30 minutes using a vibration ball mill to obtain organic-inorganic composite filler CF-1, which consisted of amorphous organic-inorganic composite particles. The average particle size and yellowness index of the resulting CF-1 were measured using the methods described below. The average particle size and yellowness index were found to be 18 μm and 24, respectively.

[0095] <Method for measuring average particle size> In the SEM (magnification: 50,000 times) photograph of the powder sample F-1, image processing was performed using image analysis software ("IP-1000PC", manufactured by Asahi Kasei Engineering Co., Ltd.), and the maximum diameter of each of 30 or more particles randomly selected from among 100 or more spherical particles whose overall shape could be confirmed within the field of view: x i (i is a natural number from 1 to n) (nm) are measured and the sum is: Σx i The average primary particle size was calculated by dividing by the number of measured particles: n (a natural number of 30 or more).

[0096] <Method for measuring yellowness index (YI)> The yellowness of powder or granules may be measured directly using the powder or granules as a sample, but due to the nature of the measuring equipment, a mixture of D-2.6E and 3G (mass ratio of D-2.6E / 3G = 70 / 30) was used as the standard monomer composition, and a composition consisting of 60 mass% of the powder or granule to be measured and 40 mass% of the standard monomer composition was used as the measurement sample, and the yellowness calculated as follows was (for convenience) taken as the yellowness of the powder or granules.

[0097] Specifically, 60 parts by mass of CF-1 and 40 parts by mass of the standard monomer were mixed to form a paste. Next, a mold with a 7 mm diameter x 3 mm thick hole was prepared, the bottom of the hole was sealed with polypropylene film, and the paste was introduced into the hole. A polypropylene film was placed on the top of the hole and pressed against it to form a measurement sample. The tristimulus values ​​(X, Y, and Z) were measured against a white background using a Nippon Denshoku spectrophotometer (SE7700), and the yellowness index (YI) was calculated based on the formula: yellowness index (YI) = 100(1.28X - 1.06Z) / Y.

[0098] Production Example 6 Production of CF-2 100 g of the inorganic filler F-3 obtained in Production Example 3 was added to water, and a dispersion was obtained by dispersing the inorganic filler using a circulation mill, SC Mill. Next, γ-methacryloyloxypropyltrimethoxysilane and acetic acid were added to water and stirred to obtain a homogeneous solution with a pH of 4. This solution was added to the inorganic particle dispersion and mixed uniformly. The dispersion was then dried by spray drying at a spray pressure of 0.08 MPa and a drying temperature of 230°C using a spray dryer (Spray Dryer "NL-5" manufactured by Okawara Kakoki Co., Ltd.), which converts the dispersion into fine particles by colliding with particulate air at the nozzle tip. The spray-dried inorganic powder was then vacuum-dried at 120°C for 15 hours to obtain a powder granule consisting of inorganic agglomerated particles. Next, 80 g of the inorganic aggregated particles was mixed with a polymerizable monomer solution containing 20 g of UDMA as a polymerizable monomer, 0.09 g of AIBN as a polymerization initiator, and methanol as an organic solvent. After confirming that the mixture had become a slurry, the mixture was allowed to stand for 1 hour. The mixture was then dried for 1 hour under reduced pressure of 10 hectopascals and heated to 40°C (using a hot water bath) while stirring on a rotary evaporator. The resulting powder, obtained after removing the organic solvent, was heated in a N2-pressurized rocking mixer for 1 hour to polymerize and cure the polymerizable monomer in the powder, yielding a roughly spherical organic-inorganic composite filler, CF-2. The average particle size and yellowness index of the resulting CF-2 were measured as in Production Example 5. The average particle size was 10 μm and the yellowness index was 5.

[0099] Table 2 shows the compositions of the organic-inorganic composite fillers CF-1 and CF-2 and the above measurement results.

[0100] [Table 2]

[0101] 3. Preparation and evaluation of dental hardenable compositions In the examples and comparative examples, dental curable compositions were prepared using the inorganic filler, the organic-inorganic composite filler, and a polymerizable monomer component, a pigment, etc., and then evaluated. The polymerizable monomer component and the evaluation method are described below.

[0102] (1) Polymerizable monomer component Monomer compositions M1 to M3 were prepared by mixing the polymerizable monomers (A) and polymerization initiators (D) shown below in the compositions shown in Table 3 (the numbers in parentheses after the abbreviations in the columns for polymerizable monomers and polymerization initiators in Table 3 represent parts by mass).

[0103] <Polymerizable monomer> BisGMA: 4-(3-methacryloyloxy-2-hydroxypropyloxy)phenyl]propane UDMA: 1,6-bis(methacrylethyloxycarbonylamino)trimethylhexane 3G: Triethylene glycol dimethacrylate <Polymerization initiator> CQ: Camphorquinone DMBE: Ethyl dimethylaminobenzoate DPIC: Diphenyliodonium chloride · MDEOA: Methyldiethanolamine.

[0104] [Table 3]

[0105] (2) Evaluation method <Method for measuring yellowness index (YI) of cured product of dental curable composition> A 1 mm thick polyacetal mold with a 7 mm diameter through-hole was prepared, the bottom of the hole was sealed with polypropylene film, and the dental curable composition to be measured was then filled in. A polypropylene film was placed on the top of the hole and pressed against it, and then a dental light irradiator (Tokuso Power Light, manufactured by Tokuyama Dental Co., Ltd.; light output density 700 mW / cm) was used. 2The dental curable composition was cured by irradiating the dental curable composition with light for 30 seconds using a 1 mm thick cured body sample. The color tone of the reflected light when irradiated with auxiliary illuminant C was measured using a spectrophotometer (SE7700) manufactured by Nippon Denshoku Corporation under white background conditions, and the tristimulus values ​​(X, Y, Z) obtained were used to calculate the color tone of the dental curable composition. Yellowness index (YI)=100(1.28X-1.06Z) / Y was calculated using

[0106] <Method for measuring the contrast ratio (C) of a cured product of a dental hardenable composition> The cured body sample used in the above yellowness measurement was irradiated with auxiliary illuminant C, and the color tone of the reflected light was measured under white and black background conditions using a spectrophotometer (SE7700) manufactured by Nippon Denshoku. Based on the Y value obtained under the black background: Yb and the Y value obtained under the white background: Yw, the following formula was used: C=Yb / Yw The contrast ratio (C) of the cured body was calculated from the above.

[0107] <Method for measuring surface hardness of cured product of dental hardenable composition> The hardness of the cured product was measured by the following method. A dental curable composition paste was filled into a polytetrafluoroethylene mold with a hole of 7 mmφ×1.0 mm, and in a state where it was pressed against polypropylene, it was irradiated from one side for 30 seconds using a visible light irradiator Power Light (manufactured by Tokuyama Corporation) to obtain a cured product. The diagonal length of the indentation made in the test piece of the obtained cured product was measured using a Vickers indenter with a load of 100 gf and a load holding time of 30 seconds using a microhardness tester (MHT-1 model manufactured by Matsuzawa Seiki). The following formula was used: HV=F / S=2Fsinθ / 2d 2 =1.8544F / d 2 The Vickers hardness (HV) was calculated from the above formula and used as the surface hardness. In the above formula, F is the load (kgf), and S is the surface area of ​​the indentation (mm 2 ), d is the diagonal length of the indentation (mm), and θ is the facing angle of the diamond indenter (136°).

[0108] <Method for measuring flexural strength of cured product of dental hardenable composition> The dental curable composition paste was filled into a stainless steel mold using a filler, and in this state, the mold was pressed with polypropylene and exposed to a visible light irradiator, Power Light (manufactured by Tokuyama Dental Corporation; light output density 700 mW / cm). 2 The specimen was then adhered to polypropylene and irradiated with light for 30 seconds x 3 times from one side using a #1500 waterproof abrasive paper. The specimen was then adhered to polypropylene and irradiated with light for 30 seconds x 3 times from the other side to obtain a cured product. The cured product was then trimmed into a 2 x 2 x 25 mm square column using #1500 waterproof abrasive paper. This specimen was then mounted on a testing machine (Shimadzu Corporation, Autograph AG5000D) and the three-point bending fracture strength was measured at a support distance of 20 mm and a crosshead speed of 1 mm / min. The following formula was used: σ B =(3PS) / (2WB 2 ) The bending strength σ obtained from B (Pa) was calculated. Five test pieces were evaluated and their σ B The bending strength was determined as the average value of the above. In the above, P represents the load (N) at the time of fracture of the test piece, S represents the distance between supports (m), W represents the width (m) of the test piece, and B represents the thickness (m) of the test piece.

[0109] <Method for evaluating paste properties (stickiness) of dental curable compositions> The paste was placed on a paper mixer, and the paste was spread with a filler. The stickiness of the paste was evaluated according to the following criteria. ◎: No paste adheres to the filling device, and operability is good. 〇: A little sticky but tolerable. ×: The paste is very sticky and sticks to the filling device.

[0110] <Method for measuring color tone of a cured product of a dental curable composition> The cured product sample used in the yellowness measurement was measured in accordance with JIS Z8729. Specifically, the color tone of the reflected light when irradiated with auxiliary illuminant C was measured using a color difference meter (SE7700 manufactured by Nippon Denshoku Co., Ltd.) under white background conditions, and the lightness L * , and chromaticity a * , b * Each of them asked for the following.

[0111] Example 1 In a dark place, 100.7 parts by mass of monomer composition M1, 300 parts by mass of organic-inorganic composite filler CF-1, 140 parts by mass of inorganic filler F-1, and 60 parts by mass of F-3 were mixed and kneaded to prepare an untoned paste-like curable composition (untoned paste) that served as the base composition. The untoned paste was measured for contrast ratio and yellowness index (YI) according to the evaluation methods described above. The results are shown in Table 5. Furthermore, the untoned paste contains 500×10 titanium dioxide particles as a white pigment for 1 part by mass of the untoned paste. -6 ) parts by mass and blue pigment Pigment Blue: 0.2 x 10 -6 Parts by mass were added and toning was performed to prepare a paste-like dental curable composition. The composition of the obtained dental curable composition is summarized in Table 4. The obtained dental curable composition was also subjected to the above-mentioned evaluation. The results are shown in Table 5. Note that the parts by mass in Table 4 indicate the parts by mass relative to 100 parts by mass of the polymerizable monomer (A), and the parts by mass of the colorant (E) in Table 5 indicate the parts by mass relative to 1 part by mass of the untoned paste.

[0112] [Table 4]

[0113] [Table 5]

[0114] Examples 2 to 7 and Comparative Examples 1 to 4 An untoned paste and a dental hardenable composition were prepared and evaluated in the same manner as in Example 1, except that the compositions were changed as shown in Tables 4 and 5. The results are shown in Table 5.

[0115] As can be seen from the results of Examples 1 to 7, in the dental composition of the present invention, the yellowness index of the cured product of the base composition without color matching was 10 or less, and by further color matching using a small amount of white pigment and blue pigment, the yellowness index was 5 or less, Yb / Yw was 0.75 or less, and the brightness L * It is possible to obtain a hardened product having a viscosity of 79 to 85.

[0116] In Example 2, the blending ratio of crushed filler, which has a high yellowness, was high, while the blending ratio of cored filler to the silica-based composite oxide particles was reduced to 60%. In this case, as shown in Table 5, the YI value of the untoned 1 mm cured product was higher than in Example 1, but it was possible to reduce the yellowness to 5 or less by toning. In this case, a larger amount of pigment was required to suppress the yellowness compared to Example 1, and therefore the transparency of the cured product was slightly reduced, but the Yb / Yw value was within the range of 0.75, making it possible to adjust the color tone to have sufficient transparency.

[0117] A comparison between Example 3 and Example 1 shows that the use of an impregnated organic-inorganic composite filler is more effective in suppressing the yellowness of the cured body than the use of a crushed organic-inorganic composite filler.

[0118] In Example 4, by adding an initiator that promotes curing to the polymerizable monomer, the amount of camphorquinone, which has absorption in the visible light region, can be reduced, thereby making it possible to further reduce yellowness.

[0119] In Example 5, by increasing the ratio of silica-based composite oxide particles, it was possible to further reduce the yellowness of the cured body, but there was a tendency for the stickiness of the paste to increase slightly as the amount of organic-inorganic composite filler was reduced.

[0120] As shown in Examples 6 and 7, by changing the polymerizable monomer and silica-based composite oxide particles, it is possible to adjust the transparency and physical properties of the cured product.

[0121] As can be seen from the results shown in Table 5, the difference between Example 1 and Comparative Example 1 is that Comparative Example 1 did not contain an organic-inorganic composite filler. In this case, the paste became sticky and did not achieve good operability. In Comparative Example 2, when composite oxide particles having a silica core were not contained, the yellowness of the untoned 1 mm cured product increased, making it difficult to adjust the color tone to a reduced yellowness while maintaining high transparency and brightness. Furthermore, in Comparative Example 3, in which the amount of white pigment was increased to the same composition as Comparative Example 2, the effect of reducing the yellowness was small, and the cured product became opaque. Furthermore, in Comparative Example 4, in which the proportion of blue pigment added to the composition of Comparative Example 2 was increased, it was possible to reduce the yellowness of the cured product, but the brightness of the cured product decreased due to the influence of the blue pigment, and it was not possible to obtain a cured product with the desired color tone.

Claims

1. A dental curable composition comprising a base composition including 100 parts by mass of a polymerizable monomer (A), 60 to 420 parts by mass of an organic-inorganic composite filler (B) made of a powdery material constituted by particles made of a composite of inorganic particles and a resin, 60 to 420 parts by mass of an inorganic filler (C) made of an inorganic powdery material constituted by inorganic particles, and 0.5 to 5.0 parts by mass of a polymerization initiator (D), As the colorant (E), 50 to 1000×10 －６ parts by weight of a white colorant (e1) and 0.01 to 3×10 －６ parts by mass of a blue colorant (e2), 60% by mass or more of the inorganic filler (C) is composed of powder particles (c1) having an average primary particle diameter of 350 to 600 nm and constituted by spherical particles each having a spherical core made of silica and a silica-based composite oxide coating layer coating the outer surface of the spherical core; For a sample having a certain thickness made of a specific material, based on the tristimulus values ​​X, Y, and Z of the XYZ color system obtained by reflection measurement under geometric condition c of JIS Z8722 5.3.1 using auxiliary illuminant C specified in JIS Z8720, Formula: YI=100(1.28X-1.06Z) / Y The yellowness index of the material is determined by the following formula: A plate-shaped sample having a thickness of 1 mm and made of a specific material is irradiated with auxiliary illuminant C against a black background and a white background, and the color tone of the reflected light is measured using a spectrophotometer to obtain tristimulus values ​​of the XYZ color system. The tristimulus values ​​are measured based on Yb, which is the Y value against the black background, and Yw, which is the Y value against the white background. The value calculated as the ratio of the two, Yb / Yw, is defined as the contrast ratio of the material. For a plate-shaped sample of a specific material having a thickness of 1 mm, the color tone of the reflected light when irradiated with auxiliary illuminant C on a white background is measured using a spectrophotometer to obtain the L ＊ , a ＊ and b ＊ L obtained by measuring ＊ When the value of is the brightness of the material, The dental curable composition has a yellowness index (YI) of −5.0 to 5.0, a contrast ratio (Yb / Yw) of 0.55 to 0.75, and a lightness (L ＊ to give a hardened product having a viscosity of 79 to 85. A dental hardenable composition comprising:

2. 2. The dental curable composition according to claim 1, wherein the ratio t / d of the average radius d (nm) of the spherical core particles constituting the powder granules (c1) to the average thickness t (nm) of the silica-based composite oxide coating layer is 0.4 to 0.

9.

3. 2. The dental curable composition according to claim 1, wherein the white colorant (e1) is titanium dioxide, and the blue colorant (e2) is a blue organic pigment.

4. A bleach shade composite resin comprising the dental hardenable composition according to claim 1.

5. 10. A method for producing the dental hardenable composition of claim 1, comprising: a mixing step of mixing 100 parts by mass of the polymerizable monomer (A), 60 to 420 parts by mass of the organic-inorganic composite filler (B), 60 to 420 parts by mass of the inorganic filler (C), 0.5 to 5.0 parts by mass of the polymerization initiator (D), and the colorant (E), In the mixing step, the curable composition obtained after the mixing step has a yellowness index: YI of −5.0 to 5.0, a contrast ratio: Yb / Yw of 0.55 to 0.75, and a brightness: L ＊ the blending amounts of the white colorant (e1) and the blue colorant (e2) are adjusted within the above-mentioned ranges so as to give a cured product having a viscosity of 79 to 85. A method for producing a dental hardenable composition, comprising:

6. A plurality of hardenable composition samples were prepared by varying the blending amounts of a white colorant (e1) and a blue colorant (e2) in a plurality of hardenable compositions having the same composition as the base composition in the target dental hardenable composition, and the contrast ratio, the yellowness index (YI) and the brightness (L) were measured for the cured products of these samples. ＊ and adjusting the amounts of the white colorant (e1) and the blue colorant (e2) based on a correlation between the measurement result and the amounts of the white colorant (e1) and the blue colorant (e2) blended.

7. 6. The method for producing a dental curable composition according to claim 5, wherein a paste-like composition obtained by mixing 60 parts by mass of the organic-inorganic composite filler (B) with 40 parts by mass of a standard monomer composition consisting of 70% by mass of 2,2-bis[4-(methacryloyloxyethyl)phenyl]propane and 30% by mass of triethylene glycol dimethacrylate is subjected to measurement of the yellowness index (YI) so that the paste-like composition has a constant thickness, and the organic-inorganic composite filler (B) whose YI is confirmed to be within a range of 0 to 25 is used in the mixing step.

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