Dental curable composition and dental curable composition package

Abstract

To provide a dental curable composition capable of giving a cured product having excellent strength, transparency and X-ray contrast, and suitable as a high-flow type flowable CR for lining having high flowability and appropriate consistency.SOLUTION: A dental curable composition containing 100 pts.mass of a liquid polymerizable monomer component and 90 to 290 pts.mass of silica or silica-based composite oxide powder particles having an average primary particle size of 50 nm to 1 μm is blended with 10 to 20 pts.mass of an organic-inorganic composite powder particles having an average particle size of 10 to 20 μm and a specific surface area of 3 to 5 m2 / g, which is composed of particles consisting of a composite in which crystalline rare earth metal fluoride powder particles having amorphous properties such that the full width at half maximum of a main peak in X-ray diffraction measurement is 0.3° or more is dispersed in a resin matrix, as a radiopaque filler.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a dental material capable of replacing all or part of natural teeth in the field of dentistry, in particular to a dental hardenable composition having high fluidity and high X-ray contrast properties that can be suitably used as a dental flowable composite resin for lining applications, and a packaged product thereof. [Background technology]

[0002] Dental hardenable compositions contain polymerizable monomers, inorganic fillers, and polymerization initiators as their main components. Among these, composite resins (hereinafter sometimes abbreviated as "CR") are one of the most widely used materials in dental treatment as materials for repairing cavities after removing tooth defects or caries.

[0003] Inorganic fillers are blended to improve mechanical properties such as the strength of the composite resin hardened body, but generally, as the blending amount of inorganic fillers increases, the strength of the hardened body increases while the fluidity of the paste decreases, and it is known that the aesthetics and surface smoothness of the hardened body are affected by the particle shape and refractive index of the blended inorganic filler. Therefore, in composite resins (CR), the type and blending amount of inorganic fillers are appropriately determined according to the desired physical properties. As the inorganic filler blended in CR, powders made of silica-based particles are often used from the viewpoint of the aesthetics (or transparency) of the hardened body and because the paste properties can be controlled by treatment with a silane coupling agent (see Patent Documents 1 and 2).

[0004] Also, it is common to incorporate an X-ray contrast material (X-ray contrast agent) in order to impart the X-ray contrast required for distinguishing the composite resin filled area from the natural tooth area by X-ray photography or CT scan after dental treatment (see Patent Document 3). Furthermore, it is known that some X-ray contrast materials are difficult to reduce the transparency of the hardened body even when the amount is increased to increase the X-ray contrast (see Patent Documents 4 and 5).

[0005] That is, Patent Document 3 describes an organic / inorganic filler that can impart high X-ray contrast properties to a cured product and can appropriately control the viscosity of a dental curable composition, as follows: "An organic resin layer that includes inorganic agglomerated particles made of SiO2-ZrO2 having an average particle size of 0.15 μm and YbF3 having an average particle size of 0.05 μm, a polymerized cured product of a polymerizable monomer that covers the surface of each inorganic agglomerated particle and bonds each inorganic primary particle to each other, and an ionic surfactant, and has micropores with a pore size of 1 to 500 nm at a density of 0.01 to 0.30 cm." 3 / g” is described.

[0006] Furthermore, Patent Documents 4 and 5 describe, as radiopaque fillers that can impart the radiopaqueness required for a dental hardenable composition, are unlikely to reduce the transparency of the hardened body, and enable aesthetic restoration, the following: "a radiopaque filler made of powder particles containing crystalline rare earth metal fluoride particles as a main component, and having an X-ray diffraction pattern in which the full width at half maximum of the maximum intensity peak derived from the crystalline rare earth metal fluoride particles is 0.3° or more" and "a radiopaque filler made of organic / inorganic powder particles that is composed of organic / inorganic composite particles obtained by crushing a composite in which powder particles made of crystalline rare earth metal fluoride are dispersed in a resin matrix, and has an X-ray diffraction pattern in which the full width at half maximum of the maximum intensity peak derived from the rare earth metal fluoride is 0.3° or more."

[0007] In addition, in recent years, CR has been developed as a flowable composite resin (flowable CR) that is provided as a package filled in a syringe to which a needle with a small hole called a needle tip can be attached, and paste can be directly filled into the cavity from the tip of the needle after the needle tip is attached. The flowable CR has the fluidity that enables the above-mentioned usage form and can achieve a certain hardened body strength and aesthetics, and is widely used in clinical settings because it allows for easier tooth restoration. As the above-mentioned flowable CR, there are known low-flow types that are mainly used in cases where the occlusal surface needs to be reproduced, and high-flow types that are mainly used for lining (back layer) in which a thin layer of paste is applied to the cavity (for the purpose of forming a layer to block the opening of the dentinal tubules that open into the cavity and prevent external stimuli from being transmitted to the dental pulp).

[0008] For these types of flowable CR, it is desirable to have a good "consistency" that allows the amount of fluid paste to be controlled with delicate force without greatly increasing the force applied to the piston when discharging the fluid paste from a syringe equipped with a needle tip, and to achieve both high fluidity and high strength after hardening. "Consistency" is an index that indicates the hardness (softness) of the fluid paste, and is evaluated by how easily it spreads when a load is applied.

[0009] On the other hand, the paste properties required for each type are slightly different depending on the application. That is, the low-flow type is required to have low so-called "droopiness", which is evaluated as the tendency for the paste to drip when applied to a vertical surface, and good "shapeability" (the property of being unlikely to deform due to natural flow when left to stand and being able to maintain its shape) so that the paste does not deform from the time the shape is adjusted after filling until it hardens. On the other hand, for the high-flow type, although it is important to have an appropriate consistency, shapeability is not so important ("droopiness" may increase), and rather high "flowability" is required so that the paste naturally spreads and spreads on a horizontal surface (in an unloaded state).

[0010] There are also differences in the degree of X-ray contrast required to distinguish between composite resin filled areas and natural tooth areas using X-rays or CT scans after dental treatment. Because the composite resin hardened layer formed by the lining is thin, high-flow types require higher X-ray contrast. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] International Publication No. 2014 / 083842 Brochure [Patent Document 2] International Publication No. 2020 / 031444 Brochure [Patent Document 3] JP 2014-177443 A [Patent Document 4] International Publication No. 2023 / 042598 Brochure [Patent Document 5] JP 2023-118513 A Summary of the Invention [Problem to be solved by the invention]

[0012] As mentioned above, high X-ray contrast is required for high-flow type flowable composite resins (CR) for lining, but for aesthetic reasons, it is preferable that the cured body has relatively high transparency. In addition, considering that it is used with a syringe, ease of use during use is also important.

[0013] Therefore, the present invention aims to provide a dental hardenable composition that can give a hardened product that has sufficient strength and exhibits high X-ray contrast while maintaining transparency, and that can be suitably used as a high-flow type flowable CR for lining that has high "flowability" and "appropriate consistency," as well as to provide a convenient package in which such a dental hardenable composition is contained in a syringe-type container. [Means for solving the problem]

[0014] The present invention has been made to solve the above-mentioned problems, and a first aspect of the present invention is a dental curable composition comprising a polymerizable monomer component (A) having a viscosity at 25°C of 100 to 500 mPa s, the polymerizable monomer component being composed of one type of radically polymerizable monomer or a mixture of a plurality of radically polymerizable monomers, a radiopaque filler (B), and an inorganic filler (C) other than the radiopaque filler, The X-ray impermeable filler (B) is a composite in which crystalline rare earth metal fluoride powder particles constituted by particles of a crystalline rare earth metal fluoride are dispersed in a resin matrix, the composite being constituted by organic-inorganic composite particles constituted by a composite in which the average content of the crystalline rare earth metal fluoride powder particles in the composite is 60 to 90 mass %, the full width at half maximum of the maximum intensity peak derived from the rare earth metal fluoride particles measured by an X-ray diffraction measurement method is 0.3° or more, the average particle size defined by the median diameter in a volume-based particle size distribution obtained by a laser diffraction-scattering method is 10 to 20 μm, and the specific surface area measured by a nitrogen adsorption method is 3 to 5 m 2 / g of organic-inorganic composite powder (b), The inorganic filler contains silica or silica-based composite oxide powder (c) which is composed of primary particles or aggregate particles thereof made of silica or silica-based composite oxide and has an average primary particle diameter of 50 nm to 1 μm as measured by electron microscope image analysis, the content of the organic-inorganic composite powder (b) and the content of the silica or silica-based composite oxide powder (c) relative to 100 parts by mass of the polymerizable monomer component (A) are (b): 10 to 20 parts by mass and (c): 90 to 290 parts by mass, respectively; The dental hardenable composition is characterized in that

[0015] 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 proportion of the mass of the organic-inorganic composite powder (b) to the total mass of the organic-inorganic composite powder (b) and the silica-based composite oxide powder (c) is 4 to 18 mass%.

[0016] In addition, a second form of the present invention is a dental curable composition packaged product in which a dental curable composition is contained in a container, the container being a syringe-type container having a cylindrical barrel having a cylindrical tip at its tip and a nozzle at its tip to which a needle tip can be attached, a cap that is detachably attached to the nozzle and seals the discharge outlet, or a needle tip attached to the nozzle and a cap that is detachably attached to a tip region of the needle of the needle tip and seals the needle, and a plunger having a gasket at its tip and an operating portion at its rear end, the gasket being slidably inserted from the rear end of the barrel to form a fluid storage space in the barrel on the tip side of the gasket, and the dental curable composition according to claim 1 is contained in the fluid storage space.

[0017] In the dental curable composition package of the above form (hereinafter also referred to as "the package of the present invention"), it is preferable that the dental curable composition of the present invention, which has a "flow value" of 8.0 to 10.0 (mm) defined as the spreading diameter (mm) of the paste when 0.1 g of the dental curable composition is discharged onto a polypropylene film and then allowed to stand horizontally in an incubator at 37°C for 2 minutes, is contained in the fluid containing space.

[0018] A third aspect of the present invention is a flowable composite resin package for lining, which comprises the package of the present invention according to the above-mentioned preferred embodiment. Effect of the Invention

[0019] According to the present invention, there is provided a dental hardenable composition which contains a certain amount of inorganic filler from the viewpoint of hardened body strength, which can impart high X-ray contrast to the hardened body without reducing transparency, and which is provided in a syringe-type package and has "flowability" and "appropriate consistency" that provide good operability when used directly by attaching a needle tip, and which can be suitably used as a high-flow type flowable CR for lining.

[0020] In addition, the organic-inorganic composite powder (b) functioning as the X-ray opaque filler (B) in the dental hardenable composition of the present invention is composed of (solid) non-porous particles, and therefore the average particle size and specific surface area are unlikely to change due to the influence of the kneading conditions (kneading force and kneading time) when preparing the dental hardenable composition of the present invention by mixing the respective components. Therefore, by controlling the average particle size and specific surface area of ​​the organic-inorganic composite powder (b) within a predetermined range, it is possible to almost certainly prepare the dental hardenable composition of the present invention.

[0021] In addition, since the package of the present invention is a syringe-type package that packages the dental hardenable composition having the above-mentioned characteristics, its use not only enables easy use by simply attaching a needle tip, but also makes it possible to easily form a lining (hardened layer) that has high X-ray opacity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] 1. Overview of the Invention It is believed that it is possible to impart X-ray contrast without reducing the transparency of the cured body by blending the X-ray opaque filler using a crystalline rare earth metal fluoride powder having a full width at half maximum of the maximum intensity peak in an X-ray diffraction pattern of 0.3° or more as disclosed in Patent Document 4 and Patent Document 5, or the YbF3 in the organic-inorganic composite filler having a full width at half maximum of the maximum intensity peak in an X-ray diffraction pattern of 0.3° or more as disclosed in Patent Document 3. Even when the transparency of the cured body is not particularly important, it is preferable to make the X-ray opaque filler usable from the viewpoint of diversion of raw materials for applications requiring transparency. However, Patent Document 4 and Patent Document 5 do not consider the "consistency" or "flowability" of the dental polymerizable composition blended with the above-mentioned X-ray opaque filler.

[0023] Therefore, the present inventors have investigated the paste properties when the above-mentioned X-ray opaque filler is blended into a curable composition for high-flow type flowable CR containing a certain amount of powder particles made of silica-based particles in order to give a cured body with a certain degree of aesthetics and strength. As a result, the inventors investigated the paste properties when the X-ray opaque filler disclosed in Patent Document 4, that is, a crystalline rare earth metal fluoride powder particle (or a surface-treated product thereof) having a full width at half maximum of the maximum intensity peak in the X-ray diffraction pattern of 0.3° or more, is blended, and it has been found that the "flow property" tends to decrease as the blending amount increases. In addition, when various X-ray opaque fillers made of organic-inorganic composite fillers disclosed in Patent Document 5 are manufactured and blended, it has been found that the "flow property" and the physical properties of the cured body differ depending on the system, and although it was possible to obtain a cured body with high X-ray opacity without significantly reducing the "flow property" and the transparency of the cured body, in many cases, the "flow property" decreases or the strength of the cured body decreases. Furthermore, when a porous organic-inorganic composite filler such as that disclosed in Patent Document 3 is used, not only does the use of an ionic surfactant become essential, but it has also become clear that the "flow properties" tend to decrease.

[0024] Based on these new findings, further investigation was conducted on the system containing the radiopaque filler disclosed in Patent Document 5. As a result, it was found that the "flow property" and the strength of the cured body are affected not only by the amount of the filler but also by the average particle size and specific surface area of ​​the organic-inorganic composite filler that serves as the radiopaque filler, and that by controlling these within a given range, it is possible to stably obtain the desired effects, which led to the completion of the present invention.

[0025] The reason why the "flowability" is decreased when the X-ray opaque filler disclosed in Patent Document 4 is added is that the polarity of the zeta potential measured in neutral water (for example, dispersed in ion-exchanged water of pH 7) of silica-based particles is negative, and the polarity of the crystalline rare earth metal fluoride particles is positive. Therefore, as the amount of the X-ray opaque filler added increases, the electrostatic interaction between these particles becomes stronger, forming a tertiary network structure, which is thought to decrease the "flowability". In the dental hardenable composition of the present invention, the crystalline rare earth metal fluoride powder is made into an organic-inorganic composite powder having a suitable particle size and specific surface area, which significantly weakens the electrostatic interaction, and therefore, it is thought that the decrease in the "flowability" is avoided. In addition, even if the organic-inorganic composite powder is made of microporous particles as disclosed in Patent Document 3, or even if it is made of (solid) non-porous particles, if the average particle size is small and the content of fine particles is high, and the specific surface area is too large, it is difficult to prevent the decrease in "flow property". In addition, even if the organic-inorganic composite powder is made of (solid) non-porous particles, if the average particle size is too large (the specific surface area is too small), not only does the "flow property" change and the discharge feeling is easily deteriorated, which is probably due to settling in the dental curable composition during long-term storage, but the coarse particles in the dental curable composition become the starting point of destruction, and the strength of the hardened product tends to decrease.

[0026] As described above, lining (high-flow type) flowable CR is generally provided in a packaged form housed in a syringe-type container, but no lining (high-flow type) flowable CR is known that is provided in such a packaged form and can form a lining (hardened layer) with high X-ray impermeability without reducing transparency. The dental hardenable composition of the present invention is suitable for the above-mentioned packaged form, and the packaged product of the present invention is characterized in that the dental hardenable composition of the present invention is housed in a syringe-type container, and has the advantage of being excellent not only in the physical properties of the hardened product but also in operability during use.

[0027] Here, the syringe-type container can be any container used for conventional lining (high-flow type) flowable CR without any particular restrictions. Such a syringe-type container is usually a cylindrical barrel having a nozzle and a tip on which a needle tip can be attached, a cap detachably attached to the tip to seal the nozzle, or a needle tip attached to the tip and a cap detachably attached to the tip region of the needle of the needle tip to seal the needle, and a plunger having a gasket at the tip and an operating part at the rear end, and a fluid storage space is formed in the barrel on the tip side of the gasket by slidably inserting the gasket from the rear end of the barrel, and the fluid (dental curable composition) stored in the fluid storage space can be discharged from the nozzle by pressing the operating part of the plunger with the needle tip with the needle tip released attached to the tip.

[0028] The dental curable composition of the present invention and the package of the present invention will be described in detail below. In this specification, unless otherwise specified, the expression "x to y" using the numerical values ​​x and y means "x or more and y or less". In such an expression, when a unit is added only to the numerical value y, the unit is also applied to the numerical value x. In addition, 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".

[0029] 2. Polymerizable monomer component (A) As the polymerizable monomer component (A) of the dental curable composition of the present invention, one type of radically polymerizable monomer or a mixture of multiple radically polymerizable monomers having a viscosity of 100 to 500 mPa·s at 25°C is used. If the viscosity is less than 100 mPa·s, sedimentation of the organic-inorganic composite powder particles is likely to occur in the composition, and the fluidity of the paste is likely to change during long-term storage. If the viscosity exceeds 500 mPa·s, the fluidity of the composition (paste) is low, making it difficult to use for lining purposes. In addition, for the reason that the polymerizable monomer is easy to handle when kneading the paste using a kneader or the like, the viscosity is preferably 150 to 380 mPa·s, and particularly preferably 200 to 380 mPa·s.

[0030] The viscosity of the polymerizable monomer component (A) can be confirmed by measuring it using a dynamic viscoelasticity measuring device generally called a rheometer. In the present invention, the viscosity was evaluated using a viscoelasticity measuring device CS rheometer "CVO120HR" (manufactured by Bohlin) equipped with a cone / plate geometry of 4 cm / 2° and a temperature control system at a measurement temperature (plate temperature) of 25°C and a shear rate of 1 rps, and the average value of three measurements was taken as the viscosity.

[0031] As the radical polymerizable monomer, so long as it satisfies the above conditions, it is possible to use without any particular limitation any radical polymerizable monomer used in the dental hardenable compositions disclosed in Patent Documents 3 to 5. From the viewpoint of ease of handling and physical properties (mechanical properties and, in dental applications, adhesiveness to tooth substance) when used as a dental filling and restorative material, it is preferable to use a (meth)acrylic compound as the radical polymerizable monomer.

[0032] Examples of suitable usable (meth)acrylate polymerizable monomers include 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-(4-methacryloyloxy)-3-hydroxybutoxyphenyl]propane, 2,2-bis[4-(4-methacryloyloxy)-3-hydroxybutoxyphenyl]propane, and 2,2-bis[4-(4-methacryloyloxy)-3-hydroxybutoxyphenyl]propane. Examples of the methacryloyloxyalkylene compounds include 2,2-bis[4-(4-hydroxybutoxyphenyl)propane, 2,2-bis[4-(4-methacryloyloxy)-3-hydroxybutoxyphenyl]propane, methyl (meth)acrylate, ethyl (meth)acrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, and 1,6-bis(methacrylethyloxycarbonylamino)trimethylhexane.

[0033] Among these polymerizable monomers, bifunctional or higher polymerizable monomers, more preferably bifunctional to tetrafunctional polymerizable monomers, are preferred because of their high polymerizability and the high mechanical strength of the cured product.

[0034] 3. About X-ray opaque filling material (B) In the dental curable composition of the present invention, the X-ray impermeable filler (B) is a composite in which crystalline rare earth metal fluoride powder particles constituted by particles of a crystalline rare earth metal fluoride are dispersed in a resin matrix, the composite being constituted by organic-inorganic composite particles constituted by a composite in which the average content of the crystalline rare earth metal fluoride powder particles in the composite is 60 to 90 mass %, the full width at half maximum of the maximum intensity peak derived from the rare earth metal fluoride particles measured by X-ray diffraction measurement method is 0.3° or more, the average particle size defined by the median diameter in the volume-based particle size distribution obtained by a laser diffraction-scattering method is 10 to 20 μm, and the specific surface area measured by a nitrogen adsorption method is 3 to 5 m 2 / g of organic-inorganic composite powder (b) is used.

[0035] Here, the maximum peak half-width is determined by performing X-ray diffraction measurement of the organic-inorganic composite powder / granule (b) in the range of 2θ; 20 to 120° using an X-ray diffractometer, identifying peaks derived from crystalline rare earth fluorides in the obtained X-ray diffraction pattern (chart) with the horizontal axis being 2θ (°) and the vertical axis being diffraction intensity, and determining the full width at half maximum for the peak having the maximum intensity (for example, for YbF3, the peak corresponding to the crystal plane (1,1,1) that appears near 2θ = 28.0°), that is, the peak width at an intensity where the intensity is 50% of the peak intensity (maximum intensity) (absolute value of the difference in 2θ between the two intersections of the intensity and the peak line: unit "deg [°]"). In addition, when measuring, it is preferable to use a powder / granule from which coarse particles have been removed, for example, by using a sieve with an opening of 100 μm, as the measurement sample.

[0036] In general, there is a correlation between the full width at half maximum of the diffraction peak in X-ray diffraction measurements and the crystallite size, known as the Scherrer equation, and it is known that the crystallite size is inversely proportional to the full width at half maximum. In addition, the distortion of the crystal lattice also affects the full width at half maximum, and the larger the crystal lattice distortion, the wider the full width at half maximum tends to be. It is thought that the amorphous nature increases when the crystallite distortion is large, the crystallite diameter becomes small, and the fine crystallites are oriented in various directions, so the full width at half maximum can be said to be an index of the degree of crystallinity-amorphousness of rare earth metal fluorides.

[0037] The average particle size means the median diameter in the volumetric particle size distribution obtained by the laser diffraction / scattering method for the organic / inorganic composite powder / particle (b). The specific surface area can be measured by the nitrogen adsorption method by determining a nitrogen adsorption isotherm using a gas adsorption measuring device and calculating by the BET method.

[0038] The organic / inorganic composite powder / grains (b) basically belong to the category of the organic / inorganic powder / grains that serve as an X-ray opaque filler disclosed in Patent Document 5, specifically, "organic / inorganic powder / grains that are composed of organic / inorganic composite particles obtained by crushing a composite in which powder / grains made of a crystalline rare earth metal fluoride are dispersed in a resin matrix, and in which the full width at half maximum of the maximum intensity peak derived from the rare earth metal fluoride in the X-ray diffraction pattern is 0.3° or more." Furthermore, the above organic-inorganic composite powder, the organic-inorganic composite powder (b) used in the present invention, and the crystalline rare earth metal fluoride powder used as a raw material are basically the same as the X-ray opaque filler disclosed in Patent Document 4, which is "a powder containing crystalline rare earth metal fluoride particles as a main component and having a full width at half maximum of the maximum intensity peak derived from the crystalline rare earth metal fluoride particles in an X-ray diffraction pattern of 0.3° or more." By using this powder, the organic-inorganic composite powder satisfies the condition that the full width at half maximum of the maximum intensity peak derived from rare earth metal fluoride particles measured by X-ray diffraction measurement is 0.3° or more.

[0039] The dental hardenable composition of the present invention has a major feature in that it has a unique effect of not decreasing the "flowability" even when used for lining purposes as a high-flow type flowable CR, by selecting and using one having a specific average particle size and specific surface area from the organic / inorganic powders and particles disclosed in Patent Document 5. That is, in order to obtain the above effect, the average particle size is 10 to 20 μm, and the specific surface area measured by the nitrogen adsorption method is 3 to 5 m. 2 It is necessary to use organic-inorganic composite powder particles having an average particle size of 3 m / g. If the average particle size is less than 10 μm, the fluidity in a paste state is likely to decrease, making it difficult to obtain the high fluidity that is a feature of the present invention, and if it exceeds 20 μm, the organic-inorganic composite powder particles are likely to settle in the dental hardenable composition, causing a large change in fluidity over time, which not only tends to cause a deterioration in the feeling of ejection, but also may not satisfy the mechanical strength of the hardened body required for CR. Also, when the specific surface area is less than 3 m, 2 If it is less than 5m / g, the mechanical strength of the cured product required for CR may not be satisfied. 2 If it exceeds 1 / g, the "flowability" decreases, making it difficult to obtain the high fluidity required for high flow applications.

[0040] 4. Manufacturing method of organic-inorganic composite powder (b) As described above, except for the fact that the average particle size and specific surface area of ​​the organic-inorganic composite powder (b) used in the present invention are within specific ranges, there is no particular difference from the organic-inorganic powder disclosed in Patent Document 5. For example, in the organic-inorganic composite powder (b), the average content of the crystalline rare earth metal fluoride powder in the composite must be 60 to 90 mass%, and the Patent Document also states that the average content is preferably 60 mass% or more and 90 mass% or less.

[0041] Therefore, the manufacturing method is basically the same as that disclosed in Patent Document 5. "A method for producing organic / inorganic powder particles, the method including at least a mechanochemical treatment step of mechanochemically treating a crystalline rare earth metal fluoride powder particle to obtain a mechanochemically treated rare earth metal fluoride powder particle, a hardening step of hardening a granulation raw material composition containing a polymerizable monomer and the mechanochemically treated rare earth metal fluoride powder particle to obtain a hardened product, and a pulverization step of pulverizing the hardened product." Similarly, the organic-inorganic composite powder (b) can be produced by controlling the grinding conditions in the grinding step and further by classifying the powder after grinding.

[0042] The raw materials and manufacturing method of the organic-inorganic composite powder / particles (b) will be described below, including these and other points.

[0043] As the crystalline rare earth metal fluoride powder (raw powder) used in the mechanochemical treatment process in which the crystalline rare earth metal fluoride powder is mechanochemically treated to obtain the mechanochemically treated rare earth metal fluoride powder, powders such as ytterbium fluoride (YbF3), lanthanum fluoride (LaF3), and cerium fluoride (CeF3), which have a full width at half maximum of the maximum intensity peak derived from the crystalline rare earth metal fluoride in the X-ray diffraction pattern of less than 0.3°, can be suitably used. In view of its color tone and safety, it is preferable to use the crystalline ytterbium fluoride powder. The full width at half maximum for the raw powder and the powder obtained after the mechanochemical treatment can be determined in the same manner as the full width at half maximum for the organic-inorganic composite powder (b), except that the measurement sample is changed from the organic-inorganic composite powder (b) to the raw powder or the powder obtained after the mechanochemical treatment.

[0044] As the mechanochemical treatment for reducing the crystallinity of the raw powder particles and making the full width at half maximum 0.3° or more, that is, the treatment for applying mechanical energy to the raw powder particles (specifically, at least one of mechanical grinding, pulverization, and dispersion), a wet method, particularly a treatment using a wet bead mill, can be suitably adopted. The wet bead mill treatment is a treatment method in which a slurry in which a powder to be treated and a medium are mixed is brought into contact with a medium (beads) that is given movement by stirring, vibration, or the like, to perform pulverization and / or disintegration. When the mechanochemical treatment is carried out by the wet method, a solvent such as water or alcohol, or a medium including a polymerizable monomer can be used as the medium. However, it is preferable to use a medium that is volatile and liquid at room temperature (15 to 25°C), such as water or alcohol, because the slurry after the treatment can be used as it is for the agglomeration treatment. Materials used as the media (beads) include glass, alumina, zircon, zirconia, steel, and resin. Because of their excellent abrasion resistance and relatively low contamination, it is preferable to use alumina or zirconia beads, in particular beads with a diameter of 0.01 to 0.5 mm.

[0045] As an operating method for the wet bead mill, a circulating bead mill is preferred because it has good productivity and can process a relatively large amount of inorganic particles. The concentration of the slurry to be subjected to the mechanochemical treatment is preferably 5 to 50 parts by mass of raw powder particles per 100 parts by mass of the medium. A dispersant such as a nonionic surfactant, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, or a polymeric surfactant thereof may be added to the slurry.

[0046] The mechanochemical treatment conditions vary depending on the operating method and bead diameter of the wet bead mill used, the maximum peak half width of the crystalline rare earth metal fluoride, the concentration of the slurry, and other conditions. These conditions can be adjusted by conducting a preliminary experiment using the equipment and conditions for actually performing the mechanochemical treatment, and confirming the maximum peak half width of the crystalline rare earth metal fluoride treated with the mechanochemical treatment time. During production, the treated slurry is sampled as necessary, and the maximum peak half width is appropriately confirmed, thereby making it possible to reliably produce an X-ray impermeable filler having the desired maximum peak half width.

[0047] The full width at half maximum after the mechanochemical treatment may be 0.3° or more, preferably 0.4° or more, and more preferably 0.5° or more. The upper limit of the full width at half maximum is not particularly limited, but usually does not exceed 40°.

[0048] The polymerizable monomer used in the curing step for obtaining a cured product by curing the granulation raw material composition containing the polymerizable monomer and the mechanochemically treated rare earth metal fluoride powder is the one that serves as the resin matrix of the composite. As the polymerizable monomer, it is preferable to use a radical polymerizable monomer, particularly a (meth)acrylate monomer. As the (meth)acrylate monomer, those exemplified as the polymerizable monomer component (A) can be used. However, the (meth)acrylate monomer used as the polymerizable monomer here does not need to be the same as the (meth)acrylate monomer actually used as the polymerizable monomer component (A) in the dental curable composition of the present invention. From the viewpoint of transparency of the cured product of the dental curable composition of the present invention, the refractive index of the cured product of the polymerizable monomer component (A) at 25°C for sodium d line: n (MX) and the refractive index of the hardened polymerizable monomer (in the raw material composition for granulation) that becomes the resin matrix is ​​the refractive index for sodium d line at 25°C: n (F―MX) Absolute difference from: |n (MX) -n (F―MX) is preferably 0 to 0.1, and particularly preferably 0 to 0.05.

[0049] In addition, various polymerization initiators such as chemical polymerization initiators, photopolymerization initiators, and thermal polymerization initiators, and other additives can be used in the raw material composition for granulation as needed. In addition, the mechanochemically treated rare earth metal fluoride powder can be surface-treated with a surface treatment agent as needed. Specific examples of the polymerization initiator and other additives can be the same as those used in the dental hardenable composition of the present invention described later. However, since the polymerization in the hardening process does not need to be performed in the oral cavity, it is preferable to use a thermal polymerization initiator such as benzoyl peroxide, p-chlorobenzoyl peroxide, tert-butylperoxy-2-ethylhexanoate, tert-butylperoxydicarbonate, diisopropylperoxydicarbonate, etc., or an azo compound such as azobisisobutyronitrile, as disclosed in Patent Document 5.

[0050] The content of the mechanochemically treated rare earth metal fluoride powder in the raw material composition for granulation may be 60 to 90 mass %, expressed as the content of the powder relative to the total mass of the powder and the polymerizable monomer, and is preferably 70 to 80 mass %.

[0051] The curing of the raw material composition for granulation can be suitably carried out by curing the raw material composition for granulation by heat treatment. The heating temperature is preferably 50 to 500°C, more preferably 80 to 200°C. In addition, in order to improve the polymerization rate of the obtained cured product and reduce polymerization inhibition due to oxygen, it is preferable to carry out the heat reaction under an inert gas such as nitrogen gas together with the heat treatment. The heat treatment time is preferably 10 to 500 minutes, more preferably 20 to 200 minutes.

[0052] In the pulverization step, the hardened body (lumps) obtained in the hardening step is pulverized. As the pulverization method and pulverization conditions, it is preferable to use a ball mill or the like because it is possible to efficiently obtain an organic-inorganic composite powder having a desired average particle size and specific surface area. When using a ball mill as the pulverization method, it is preferable to use zirconia as the material of the balls used for pulverization in order to reduce contamination. The particle size of the zirconia balls used is preferably 1 to 100 mm, and more preferably 10 to 50 mm. The pulverization time in the ball mill is preferably 5 to 120 minutes, and more preferably 30 to 90 minutes.

[0053] The pulverized product thus obtained is classified by a sieve to remove coarse particles and fine particles that increase the specific surface area, thereby obtaining the organic-inorganic composite powder (b). As the classification method and classification conditions, it is preferable to use a sieve with openings corresponding to the target average particle size.

[0054] The organic-inorganic composite particles (b) thus obtained are usually used as the X-ray opaque filler (B) as is, but the surfaces of the particles may be subjected to a physical surface treatment such as plasma treatment, or a mechanical surface treatment such as prolonged friction stirring, or may be subjected to a coating treatment using a known coating agent such as silicone oil.

[0055] The amount of the X-ray opaque filler (B) in the dental hardenable composition of the present invention must be 10 to 20 parts by mass relative to 100 parts by mass of the polymerizable monomer component (A). If it is less than 10 parts by mass, it becomes difficult to obtain X-ray contrast of the dental hardenable composition, and if it exceeds 20 parts by mass, there is a risk that the mechanical strength of the dental hardenable composition will decrease. From the viewpoint of easily obtaining X-ray contrast, hardenability, and a color tone and transparency suitable for the dental hardenable composition, the amount is preferably 12 to 18 parts by mass.

[0056] 5. Inorganic filler (C) The dental curable composition of the present invention needs to contain, as the inorganic filler (C) other than the radiopaque filler, 90 to 290 parts by mass of silica or silica-based composite oxide powder (c) which is composed of primary particles or aggregate particles of silica or silica-based composite oxide and has an average primary particle diameter of 50 nm to 1 μm as measured by image analysis of electron microscope observation, relative to 100 parts by mass of the polymerizable monomer component (A).

[0057] Here, silica includes amorphous silica and quartz, and silica-based composite oxide means a composite oxide of silicon (Si) and other metalloids or metals, such as silica-zirconia, silica-titania, silica-titania-barium oxide, silica-titania-zirconia, borosilicate glass, aluminosilicate glass, fluoroaluminosilicate glass, etc. Among these, it is preferable to use at least one selected from the group consisting of silica-zirconia, silica-titania, and silica-titania-zirconia as (c).

[0058] The average primary particle diameter means an average particle diameter measured using a scanning or transmission electron microscope as follows. That is, n inorganic primary particles, which are 30 or more, preferably 100 or more, randomly selected from electron microscope images in which light and dark are clearly distinguishable and the particle contours can be distinguished, are analyzed by image analysis to obtain the circle equivalent diameter (diameter of a circle having the same area as the target particle) of each inorganic primary particle. i Find X from 1 to n i 3 Sum of: ΣX i 3 Based on the formula: X={(ΣX i 3 ) / n)} 1 / 3 The average particle (volume) diameter: X calculated by the above formula:

[0059] If the average primary particle size is less than 50 nm, the viscosity of the dental curable composition becomes high and it becomes difficult to adjust the consistency to a level suitable for ejection from a syringe equipped with a needle tip, and if the average particle size exceeds 1 μm, the polishability of the resulting cured product decreases, making it difficult to obtain a cured product with a smooth surface.The average primary particle size of the silica or silica-based composite oxide powder (c) is more preferably 0.1 to 0.8 μm.

[0060] The shape of the inorganic primary particles constituting the silica or silica-based composite oxide powder (c) is not particularly limited, and spherical, approximately spherical, or irregularly shaped particles can be used, but from the viewpoint of excellent abrasion resistance and surface smoothness, spherical or approximately spherical is preferable. Note that, approximately spherical refers to the maximum length of each particle determined by image analysis performed on 30 or more, preferably 100 or more, n inorganic primary particles selected from the photographed image used when measuring the average particle size, where L is the longest diameter of each particle. i and the minimum width, which is the diameter perpendicular to the major axis: B i Ratio: B i / L i The sum of the first to nth items: ΣB i / L i Based on the formula:Pr=(ΣB i / L i The average uniformity defined as Pr / n is 0.6 or more. The average uniformity is preferably 0.7 or more, and particularly preferably 0.8 or more.

[0061] As described above, the amount of silica or silica-based composite oxide powder (c) must be 90 to 290 parts by mass relative to 100 parts by mass of the polymerizable monomer component (A). If it is less than 90 parts by mass, the physical properties (strength, abrasion resistance, etc.) of the hardened dental hardenable composition may be reduced, and if it exceeds 290 parts by mass, it may be difficult to obtain a consistency suitable for ejection from a syringe equipped with a needle tip, and it may not be possible to obtain the desired fluidity for lining applications. From the viewpoint of achieving both high physical properties in the hardened product and operability in a paste state, the amount is preferably 140 to 270 parts by mass, particularly 150 to 250 parts by mass.

[0062] The inorganic filler (C) may contain inorganic powders (other inorganic powders) other than the silica or silica-based complex oxide powder (c) within a range that does not adversely affect the effect. Examples of such other inorganic powders include powders made of inorganic particles other than silica or silica-based complex oxides. The total amount of the other inorganic powders is preferably 5 parts by mass or less, particularly 0.5 to 3 parts by mass, per 100 parts by mass of the polymerizable monomer component (A).

[0063] 6. Polymerization initiator A polymerization initiator may be added to the dental hardenable composition of the present invention. The polymerization initiator is not particularly limited as long as it has the function of polymerizing the polymerizable monomer (A), but it is preferable to use a photopolymerization initiator or a chemical polymerization initiator used in direct dental filling and restoration applications in which hardening is often performed in the oral cavity, and it is more preferable to use a photopolymerization initiator (composition) from the viewpoint of simplicity without the need for a mixing operation, and basically the radical polymerizable monomers used in dental hardenable compositions disclosed in Patent Documents 3 to 5 can be used without any particular restrictions.

[0064] Examples of polymerization initiators used in photopolymerization include benzoin alkyl ethers, benzil ketals, benzophenones, α-diketones, thioxanthone compounds, and bisacylphosphine oxides. A reducing agent is often added to the photopolymerization initiator. Examples of reducing agents include aromatic amines, aliphatic amines, aldehydes, and sulfur-containing compounds. Furthermore, trihalomethyltriazine compounds, aryliodonium salts, and the like can be added as necessary.

[0065] Furthermore, in addition to the above-mentioned photopolymerization initiator and reducing compound, a photoacid generator is often used. Examples of such photoacid generators include diaryliodonium salt compounds, sulfonium salt compounds, sulfonate compounds, halomethyl-substituted S-triazine derivatives, and pyridinium salt compounds.

[0066] These polymerization initiators may be used alone or in combination of two or more. The amount of the polymerization initiator to be added may be selected from an effective amount depending on the purpose, and is usually used in a ratio of 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of the polymerizable monomer.

[0067] 7. Other additives The dental curable composition of the present invention may contain additives such as a polymerization inhibitor, a pigment, an ultraviolet absorbing agent, and a fluorescent agent, as long as the effects of the present invention are not impaired.

[0068] 8. Method for producing dental hardenable composition of the present invention The dental hardenable composition of the present invention can be prepared by thoroughly kneading the predetermined amounts of the above-mentioned components and each optional component added as necessary to obtain a paste, and then degassing the paste under reduced pressure to remove air bubbles. The kneading method is not particularly limited as long as it is a method that can thoroughly knead the predetermined amounts of the above-mentioned components and each optional component added as necessary.

[0069] 9. Regarding the packaging of the present invention As described above, the dental hardenable composition of the present invention has high X-ray contrast properties and high fluidity (flowability and sagging), and is therefore suitable as a high-flow type flowable composite resin (CR), in particular a flowable CR for lining.

[0070] Here, X-ray contrast is usually evaluated in terms of aluminum thickness equivalent (unit: Al%, sometimes written as %Al. 100Al% is equivalent to the X-ray contrast of 1mm thick aluminum). The practical X-ray contrast required for a dental material must be approximately equal to or greater than that of an aluminum material with the same thickness as the hardened body. Aluminum has X-ray contrast equivalent to dentin, so a 1mm thick material that has X-ray contrast equivalent to 1mm thick aluminum (Al% = 100) is considered to have X-ray contrast equivalent to dentin.

[0071] In addition, high flow type flowable CR such as flowable CR for lining is required to have high fluidity. Various methods are known for evaluating the fluidity, but in the present invention, the fluidity is evaluated by the following "flow property". That is, the prepared paste-like dental hardenable composition was left to stand in an incubator at 45°C for one day, then filled into a cylindrical syringe, and a plunger for pushing out the contents of the syringe and a needle tip with an inner diameter of φ0.58 mm (20G) were attached to the tip of the syringe. After that, it was left to stand for 30 minutes in a thermostatic chamber at 25°C, and then a circle with a diameter of 5 mm was drawn on a glass plate in advance, 0.1 g of the dental hardenable composition was discharged into the circle, and then it was left to stand horizontally for 2 minutes in an incubator at 37°C. The vertical and horizontal diameters of the paste were measured for the spread of the paste, and the flow property was evaluated based on the value (mm) calculated based on the measured values ​​using the formula: flow property (mm) = (vertical diameter + horizontal diameter) / 2. When the flowability is 8 mm or more, it can be said that the paste has high fluidity suitable for lining applications. Because of the higher fluidity and suitability for lining, 9 mm or more is preferable, and 10 mm or more is even more preferable.

[0072] Furthermore, as described above, the consistency is an index representing the hardness (softness) of a fluid paste. In the present invention, in a thermostatic chamber at 25°C, 0.2 g of paste is discharged from the tip of the syringe container onto an area within a circle of radius 5.5 mm on a polypropylene film (5 cm x 5 cm) (with the tip of the needle tip being kept as close as possible to the vertical line passing through the center of the circle), and a polypropylene film (5 cm x 5 cm) and a 50 g weight are placed on top of it and pressed for 10 seconds. After that, the pressed paste is exposed to a light intensity of 800 mW / cm. 2The paste was cured by irradiating light for 10 seconds using a halogen-type dental light irradiator (Demetron LC, manufactured by Cybron), and the vertical diameter (vertical diameter: twice the vertical radius) and horizontal diameter (horizontal diameter: twice the horizontal radius) of the obtained cured product were measured, and the consistency was evaluated based on the measured values ​​calculated by the formula: consistency [mm] = (vertical diameter + horizontal diameter) / 4. If the consistency value is less than 20 mm, the flowability and sagging of the paste described below will be small, making it difficult to obtain sufficient fluidity. On the other hand, if it exceeds 30 mm, the proportion of polymerizable monomer components in the paste will be high, and there is a risk of the strength decreasing. Thus, if the consistency value is 20 mm or more and 30 mm, it can be said that the paste has sufficient fluidity, but it is more preferable that it is 20 to 25 mm.

[0073] As shown in the examples described below, the dental hardenable composition of the present invention has suitable flowability and consistency as a flowable CR for lining, has paste properties with high storage stability (the property that these properties are unlikely to deteriorate even when stored for a long period of time), and can give a hardened product with high strength and high X-ray contrast of more than 160Al%.

[0074] As described above, these high-flow type flowable CRs are provided as a package filled in a fluid-containing space of a syringe-type container having a cylindrical barrel with a tip at the tip of the barrel that has a discharge port and a tip on which a needle tip can be attached, a cap detachably attached to the tip of the barrel to seal the discharge port, or a needle tip attached to the tip of the barrel and a cap detachably attached to the tip of the needle of the needle tip to seal the needle, and a plunger having a gasket at the tip and an operating part at the rear end, and the gasket is slidably inserted from the rear end of the barrel to form a fluid-containing space in the barrel on the tip side of the gasket, and the cap is removed, a needle tip is attached, and the dental hardenable composition of the present invention is often used as it is after removing the cap. It can be said that the dental hardenable composition of the present invention not only has the excellent features described above, but is also suitable for such a package form. The package of the present invention, in which the dental hardenable composition of the present invention is filled in the container, also has a good feeling when used. EXAMPLES

[0075] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. First, the raw materials of the compositions used in the examples and comparative examples will be described.

[0076] 1. Polymerizable monomers The compositions and viscosities of the radical polymerizable monomer mixtures (monomer components) M1 to M4 used in the examples and comparative examples are shown in Table 1. The abbreviations for the polymerizable monomers in the composition column of Table 1 respectively represent the following compounds, and the numbers in parentheses after the abbreviations represent the parts by mass used. UDMA: 1,6-bis(methacrylethyloxycarbonylamino)-2,2-4-trimethylhexane 3G: Triethylene glycol dimethacrylate D-2.6E: 2,2-bis[(4-methacryloyloxypolyethoxy)phenyl]propane ND: Nonamethylenediol dimethacrylate Bis-GMA: 2,2-bis[(3-methacryloyloxy-2-hydroxypropyloxy)phenyl]propane The viscosities of the polymerizable monomers and M1 to M4 were evaluated three times at a measurement temperature (plate temperature) of 25°C and a shear rate of 1 rps using a viscoelasticity measuring device CS rheometer "CVO120HR" (manufactured by Bohlin) equipped with a cone / plate geometry of 4 cm / 2° and a temperature control system, and the average value was regarded as the viscosity of the polymerizable monomers.

[0077] [Table 1]

[0078] 2. Polymerization initiator CQ: Camphorquinone (Tokyo Chemical Industry Co., Ltd.) DMBE: N,N-Dimethyl-p-benzoic acid ethyl ester (Tokyo Chemical Industry Co., Ltd.) ·AIBN: Azobisisobutyronitrile (Tokyo Chemical Industry Co., Ltd.).

[0079] 3. Silica-based composite oxide powder (b) F-1: Spherical silica-zirconia particles with an average primary particle diameter of 280 nm produced by the sol-gel method (average uniformity: 0.95) The above average primary particle size and average uniformity were determined by taking a photograph of the powder at a magnification of 5,000 to 100,000 times using a scanning electron microscope ("XL-30S" manufactured by Philips), processing the photographed image using image analysis software ("IP-1000PC", product name; manufactured by Asahi Kasei Engineering Corporation), and measuring the number of particles (100 or more) observed within a unit field of view of the photograph.

[0080] 4.Radio-opaque filling material (B) Organic-inorganic composite powder particles: CF-1 to CF-7 and (agglomerated) inorganic powder particle: MF-1, which were produced in the following Production Examples 1 to 8 using YbF3 (manufactured by Treibacer) having an average primary particle diameter of 100 nm, were used.

[0081] The average primary particle size of the YbF3 used as the raw material was determined in the same manner as above. The YbF3 (before the mechanochemical treatment) was measured using an X-ray diffractometer {"Smartlab" manufactured by Rigaku Corporation, radiation source: CuKα radiation}, and the full width at half maximum (deg:°) of the peak (peak observed around 2θ=28°) corresponding to the (1,1,1) plane that gives the peak with the greatest intensity was determined from the X-ray diffraction pattern (chart) with the horizontal axis being 2θ(°) and the vertical axis being diffraction intensity, and was 0.43°.

[0082] Manufacturing Example 1 Using a wet bead mill SC50 (manufactured by Mitsui Mining Co., Ltd.), a slurry was prepared by mixing 5.0 parts by mass of the raw material YbF3 with 100 parts by mass of ion-exchanged water. The slurry was dispersed for 360 minutes at a rotation speed of 3000 rpm using 100 g of φ0.3 mm zirconia beads as a medium, to perform mechanochemical treatment by a wet method. The obtained mechanochemically treated slurry was concentrated using a rotary evaporator at a bath temperature of 50°C, and the obtained powder was further dried under vacuum at 80°C for 15 hours to obtain mechanochemically treated raw powder.

[0083] Next, 25 parts by mass of a monomer composition consisting of 80 parts by mass of UDMA, 20 parts by mass of 3G, and 1 part by mass of AIBN, and 75 parts by mass of the mechanochemically treated raw powder were weighed out and mixed using an agate mortar to prepare a paste-like raw material composition. The obtained raw material composition was then thermally cured by heating at 100°C for 30 minutes under nitrogen pressure using a nitrogen pressure heat polymerization apparatus Polyner (manufactured by Towa Giken Co., Ltd.), to obtain a cured body (YbF3 particle content: 75.0% by mass) consisting of a composite in which mechanochemically treated YbF3 particles are dispersed in a resin matrix, and the obtained cured body and zirconia balls (diameter: 25 mm) were placed in a zirconia pot and subjected to a rotary grinding process for 60 minutes to obtain a pulverized product of the cured product. The pulverized product was removed from the pulverized product using a stainless steel sieve with a mesh size of 20 μm to obtain organic-inorganic composite powder CF-1.

[0084] The average particle size, specific surface area, and full width at half maximum of the peak corresponding to the (1,1,1) plane of the obtained CF-1 were measured by the following methods. The results are shown in Table 2.

[0085] <Method of measuring average particle size> A suspension was prepared by suspending 0.1 g of CF-1 in 10 mL of ion-exchanged water. The suspension was subjected to particle size distribution measurement using a particle size distribution meter (LS13-320, manufactured by BECKMAN COULTER) to obtain a volumetric particle size distribution. The particle size (median size: D50v value) that is 50% cumulative from the small diameter side of the volumetric particle size distribution was taken as the average particle size.

[0086] <Method of measuring specific surface area> 0.1 g of the above-mentioned CF-1 was placed in a sample cell, and pretreatment was performed by evacuation at 100°C for 3 hours using a pretreatment device (Microtrack-Bell Corporation's "BELPREP-miniII") After that, nitrogen was used as the adsorption gas and liquid nitrogen was used as the refrigerant to obtain a nitrogen adsorption isotherm using a gas adsorption pore distribution analyzer (Microtrack-Bell Corporation's "BELSORP-miniII"), and the specific surface area was calculated by the BET method.

[0087] <Measuring method for 2θ and full width at half maximum (deg:°) of crystal plane (1,1,1)> The full width at half maximum (deg:°) was determined in the same manner as above, except that CF-1 was used as the sample instead of the raw material YbF3.

[0088] Manufacturing Examples 2 to 7 Organic-inorganic composite powder particles: CF-2 to CF-7 were obtained in the same manner as in Production Example 1, except that the treatment time in the mechanochemical treatment of the raw material YbF3 (before the mechanochemical treatment) in Production Example 1 and / or the conditions for crushing the hardened body (crushing time and sieve opening) were changed as shown in Table 2. The average particle size, specific surface area, and full width at half maximum of the peak corresponding to the (1,1,1) plane of the obtained organic-inorganic composite powder particles were measured by the following methods in the same manner as in Production Example 1. The results are shown in Table 2.

[0089] Production Example 8 The mechanochemically treated slurry obtained by carrying out the mechanochemical treatment in the same manner as in Production Example 1 was dried using a nozzle-type spray dryer (Mini Spray Dryer B-290 Advanced; manufactured by Nippon Buchi Co., Ltd.), and inorganic agglomerated particles were obtained from the cyclone recovery section. The obtained inorganic agglomerated particles were spread on a tray and vacuum-dried at 80°C for 15 hours to obtain (agglomerated) inorganic powder: MF-1 consisting of agglomerated particles of mechanochemically treated YbF3. The average particle size, specific surface area, and full width at half maximum of the peak corresponding to the (1,1,1) plane of the obtained agglomerated filler: MF-1 were measured by the following methods in the same manner as in Production Example 1. The results are shown in Table 2.

[0090] [Table 2]

[0091] 3. Examples and Comparative Examples Example 1 A polymerizable monomer solution was prepared by completely dissolving 0.20 parts by mass of CQ and 0.5 parts by mass of DMBE as a polymerization initiator in a polymerizable monomer consisting of 70 parts by mass of UDMA and 30 parts by mass of 3G. Then, 210 parts by mass of F-1 surface-treated with γ-methacryloyloxypropyltrimethoxysilane, the polymerizable monomer solution, and organic-inorganic composite powder CF-1 were kneaded in a mortar until homogeneous to form a paste, and then the paste was degassed in a vacuum to remove air bubbles, thereby preparing a dental curable composition in the form of a paste. The dental curable composition thus obtained was filled into a syringe, and the following evaluations were performed: (1) fluidity (flowability) when kneaded for 180 minutes and 360 minutes, (2) consistency immediately after production and after 6 months of storage at 37°C, (3) feeling of ejection immediately after production and after 6 months of storage at 37°C, (4) bending strength, (5) X-ray contrast, and (6) contrast ratio (Yb / Yw) of the curable composition cured product. The evaluation results are shown in Table 4.

[0092] The above evaluations and measurements were carried out by the methods described below.

[0093] (1) Measurement method for "liquidity (flow)" The prepared dental hardenable composition in paste form was left for 1 day in a 45°C incubator, then filled into a cylindrical syringe, and a plunger for pushing out the contents of the syringe and a needle tip with an inner diameter of φ0.58 mm (20G) were attached to the tip of the syringe. After that, it was left to stand for 30 minutes in a thermostatic chamber at 25°C, a circle with a diameter of 5 mm was drawn on a glass plate in advance, 0.1 g of the dental hardenable composition was discharged into the circle, and it was left to stand horizontally for 2 minutes in a 37°C incubator. The vertical and horizontal diameters of the paste were measured to determine the spread of the paste, and the following formula was calculated based on the measured values: Fluidity [mm] = (vertical diameter + horizontal diameter) / 2 The fluidity of the paste was calculated by the above formula. The fluidity was evaluated twice, and the average value was regarded as the flowability of the paste.

[0094] (2) Measurement method of "consistency" In a temperature-controlled room at 25°C, 0.2 g of paste was dispensed from the tip of the syringe container onto a region within a circle of radius 5.5 mm on a polypropylene film (5 cm x 5 cm) (with the tip of the needle tip being as close as possible to the vertical line passing through the center of the circle), and a polypropylene film (5 cm x 5 cm) and a 50 g weight were placed on top of it, and the paste after compression was then exposed to a light intensity of 800 mW / cm. 2 The resin was cured by irradiating the resin with light for 10 seconds using a halogen-type dental light irradiator (Demetron LC, manufactured by Cybron). The vertical diameter (vertical diameter: twice the vertical radius) and horizontal diameter (horizontal diameter: twice the horizontal radius) of the obtained cured product were measured, and the following equation was calculated based on the measured values: Consistency [mm] = (vertical diameter + horizontal diameter) / 4 The consistency of the paste was calculated by the above formula. The consistency was evaluated twice, and the average value was used as the consistency of the paste.

[0095] (3) Evaluation method for "feeling of discharge" A needle tip with an inner diameter of 0.58 mm (20 G) was attached to the tip of the syringe container, and 0.2 g of paste was discharged from the tip of the needle tip onto a glass plate (5 cm x 10 cm) by pressing the plunger. The ease of pressing the plunger at this time was confirmed, and the discharge feel of the paste was evaluated according to the following evaluation criteria. Note that a discharge feel of 1 to 3 was considered to be an acceptable product. 1: The paste can be ejected even when pressed lightly, and ejection properties are very good. 2: The paste can be discharged without difficulty and has good discharge properties. 3: The paste can be ejected by pressing with some force, and ejection properties are acceptable. 4: The paste can be ejected if pressed forcefully, but ejection is poor. 5: No paste can be dispensed at all.

[0096] (4) Measurement method for "flexural strength" The dental hardenable composition paste was filled into a stainless steel mold and pressed with a polypropylene film. The paste was then irradiated with light from one side for 30 seconds x 3 times using a visible light irradiator (Tokuyama's "Power Light"), with the polypropylene film placed in different positions so that the entire surface was exposed to light. The other side was then irradiated with light for 30 seconds x 3 times to obtain a hardened body. The hardened body was trimmed into a 2 x 2 x 25 mm rectangular column shape using #1500 waterproof abrasive paper, and the specimen was mounted on a tester (Shimadzu Corporation's "Autograph AG5000D") to measure the three-point bending fracture strength at a support distance of 20 mm and a crosshead speed of 1 mm / min. A load-deflection curve was obtained, and the bending strength was calculated from the following formula. Five specimens were evaluated, and the average value was taken as the bending strength. Formula: σB=(3PS) / (2WB 2 ) The symbols in the above table represent σB: bending strength (Pa), P: load at the time of fracture of the test piece (N), S: distance between supports (m), W: width of the test piece (m), and B: thickness of the test piece (m).

[0097] (5) Measurement method for "X-ray contrast" The paste was filled into a polyethylene terephthalate mold with a hole of 15 mm in diameter and 1 mm in thickness, and the paste was pressed against a polypropylene film and exposed to light five times in total using a visible light irradiator (Tokuyama's "Power Light"), with the polypropylene film in different positions so that the entire surface was exposed to light. The polypropylene film was removed, and the hardened body was removed from the mold to be used as a sample. The prepared sample was observed using a tabletop X-ray transmission inspection device (μB1300, Matsusada Precision). In addition, when observing the sample, an aluminum step wedge with a thickness of 1 to 4 mm was observed at the same time. The observed image was imported into a dedicated image capture software (μRayVision, Matsusada Precision), and the brightness of the sample and the aluminum step wedge was measured. A calibration curve was created from the brightness of the aluminum step wedge of each thickness, and the X-ray contrast of the sample was calculated as the aluminum thickness equivalent (Al%).

[0098] (6) Measurement method for "contrast ratio (Yb / Yw) of cured product of curable composition" The compositions prepared in each of the Examples and Comparative Examples were placed in a mold with a through hole of 7 mmφ×1 mm, and polyester film was pressed onto both sides. Both sides were irradiated with light for 30 seconds each using a visible light irradiator (Tokuyama's "Power Light") to cure, and then the composition was removed from the mold, and the tristimulus value Y value (background color black and white) of the cured product was measured using a color difference meter (Tokyo Denshoku's "TC-1800MKII"). The following formula: Contrast ratio (Yb / Yw) = Y value when background color is black / Y value when background color is white The contrast ratio (Yb / Yw) was calculated based on this.

[0099] Examples 2 to 8, Comparative Examples 1 to 8 A paste-like dental curable composition was prepared in the same manner as in Example 1, except that the polymerizable monomer (A), the X-ray opaque filler (B), and the inorganic filler (C) used were changed as shown in Table 3. The prepared curable composition was produced by changing the kneading time, filled into a syringe container, and (1) the fluidity when kneading for 180 minutes and for 360 minutes, (2) the consistency immediately after production and after 6 months of storage at 37°C, (3) the discharge feeling immediately after production and after 6 months of storage at 37°C, (4) the bending strength, (5) the X-ray contrast property, and (6) the contrast ratio (Yb / Yw) of the curable composition cured product were evaluated. The evaluation results are shown in Table 4.

[0100] [Table 3]

[0101] [Table 4]

[0102] As can be seen from the results of Examples 1 to 8, the dental hardenable composition of the present invention is suitable for ejection from a syringe equipped with a needle tip, has improved paste fluidity (flowability), and does not decrease even when the kneading time is extended, exhibiting fluidity and operability suitable for a flowable composite resin for lining applications.

[0103] As can be seen from the results of Comparative Example 1, a curable composition using a polymerizable monomer (A) (M-3) having a viscosity outside the range specified in the present invention has low fluidity as a curable composition (paste), and does not have fluidity suitable for the lining application of the present invention.

[0104] As can be seen from the results of Comparative Example 2, in the case of the curable composition using the polymerizable monomer (A) (M-4) whose viscosity is below the range specified in the present invention, the filler settled in the curable composition (paste) in one out of five times, and the paste could not be discharged from the syringe container after six months of storage at 37° C. The evaluation results shown in the table are for this system.

[0105] As can be seen from the results of Comparative Examples 3 and 4, the curable compositions using the X-ray opaque fillers (B) (CF-5, CF-6) whose average particle size and specific surface area do not satisfy the requirements of the present invention have reduced fluidity, failing to obtain a fluidity suitable for lining applications, or exhibiting reduced bending strength of the cured body.

[0106] As can be seen from the results of Comparative Example 5, when the full width at half maximum of the radiopaque filler (B) is less than 0.3°, the contrast ratio increases and the dental curable composition becomes opaque.

[0107] As can be seen from the results of Comparative Examples 6 and 7, a curable composition in which the amount of X-ray opaque filler (B) does not satisfy the requirements of the present invention has reduced X-ray contrast properties or reduced bending strength of the cured body.

[0108] As can be seen from the results of Comparative Example 8, when the curable composition using the aggregated filler (MF-1) that was not organic-inorganic composite was used, the fluidity of the curable composition (paste) decreased when the kneading time was extended, and it was found that the fluidity suitable for the lining application in the present invention was not obtained.

Claims

1. A dental curable composition comprising: a polymerizable monomer component (A) consisting of one radically polymerizable monomer or a mixture of a plurality of radically polymerizable monomers, the polymerizable monomer component (A) having a viscosity at 25°C of 100 to 500 mPa·s; a radiopaque filler (B); and an inorganic filler (C) other than the radiopaque filler, The X-ray impermeable filler (B) is a composite in which crystalline rare earth metal fluoride powder particles composed of particles of a crystalline rare earth metal fluoride are dispersed in a resin matrix, and the composite is composed of organic-inorganic composite particles composed of a composite in which the average content of the crystalline rare earth metal fluoride powder particles in the composite is 60 to 90 mass %, the full width at half maximum of the maximum intensity peak derived from the rare earth metal fluoride particles measured by X-ray diffraction measurement method is 0.3° or more, the average particle size defined by the median diameter in the volume-based particle size distribution obtained by a laser diffraction-scattering method is 10 to 20 μm, and the specific surface area measured by a nitrogen adsorption method is 3 to 5 m ２ / g of organic-inorganic composite powder (b), the inorganic filler comprises silica or silica-based composite oxide powder (c) which is constituted by primary particles or aggregate particles thereof made of silica or silica-based composite oxide and has an average primary particle diameter of 50 nm to 1 μm as measured by image analysis of observation with an electron microscope; the content of the organic-inorganic composite powder (b) and the content of the silica or silica-based composite oxide powder (c) relative to 100 parts by mass of the polymerizable monomer component (A) are (b): 10 to 20 parts by mass and (c): 90 to 290 parts by mass, respectively; A dental hardenable composition comprising:

2. 2. The dental curable composition according to claim 1, wherein the ratio of the mass of the organic-inorganic composite powder (b) to the total mass of the organic-inorganic composite powder (b) and the silica-based composite oxide powder (c) is 4 to 18 mass%.

3. A dental hardenable composition package comprising a container containing a dental hardenable composition, The container comprises: a cylindrical barrel having a discharge port and a cylindrical tip at its tip to which a needle tip can be attached; a cap that is detachably attached to the nozzle and seals the discharge port, or a needle tip that is attached to the nozzle and a cap that is detachably attached to a tip region of the needle of the needle tip and seals the needle; A pusher having a gasket at a tip end and an operation portion at a rear end side, a syringe-type container in which the gasket is slidably inserted from the rear end of the barrel to form a fluid storage space in the barrel on a front side of the gasket, The dental hardenable composition according to claim 1 is contained in the fluid containing space. A dental curable composition package comprising:

4. The dental curable composition package according to claim 3, wherein the dental curable composition according to claim 1 is contained in the fluid containing space, and the dental curable composition package has a "flow value" of 8.0 to 10.0 (mm), the flow value being defined as the spreading diameter (mm) of the paste when 0.1 g of the dental curable composition is discharged onto a polypropylene film and then allowed to stand in a horizontal position in an incubator at 37°C for 2 minutes.

5. A flowable composite resin package for lining, comprising the dental hardenable composition package according to claim 4.

Images