Method for manufacturing resin blanks for dental cutting processes

Abstract

We manufacture dental cutting resin blanks that offer excellent versatility and productivity, while also providing high mechanical strength. [Solution] A resin blank for dental cutting is manufactured by a method for manufacturing a resin blank for dental cutting, characterized by comprising the steps of: (1) contacting a polymerizable monomer with at least one porous inorganic filler; (2) impregnating the porous inorganic filler with a polymerizable monomer to obtain a granular powder; and (3) placing the granular powder into a mold and curing it by pressurizing and heating.

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing a resin blank for dental cutting. [Background technology]

[0002] In recent years, the technology of fabricating prosthetic devices using dental CAD / CAM systems has rapidly become widespread. Generally, in this system, a disk-shaped or block-shaped workpiece (blank) is placed in a dental milling machine and the cutting process is performed.

[0003] The material used for cutting can be a variety of materials, including metallic materials such as titanium alloys, ceramic materials such as zirconia, alumina, and lithium disilicate, and composite resin materials made from polymerizable monomers and inorganic fillers. By selecting the material for cutting according to the purpose, a wide variety of prosthetic devices can be fabricated.

[0004] Among these, composite resin blanks for dental machining are used clinically in dental prosthetics because they have a moderate hardness that does not damage opposing teeth and excellent impact resistance.

[0005] For example, a method for manufacturing a dental cutting resin blank is described (Patent Document 1), in which a polymerizable monomer and an inorganic filler are kneaded together to form a paste, which is then polymerized and cured in a mold of a desired shape. This manufacturing method has the advantage of easily producing a dental cutting resin blank containing 20 to 70% by weight of inorganic filler, but because it requires going through a paste form, there are limitations on the amount of inorganic filler that can be used, making it difficult to impart sufficient mechanical properties.

[0006] Furthermore, Patent Document 2 describes a method for manufacturing a resin blank for dental cutting, in which an inorganic filler is pre-press-molded, and then a polymerizable monomer is immersed in the molded body and heated to polymerize it (Patent Document 2). This manufacturing method makes it possible to highly fill the inorganic filler with nanoparticles, and a resin blank for dental cutting with excellent polishability can be obtained. However, because it is necessary to immerse the molded body in a polymerizable monomer, there are limitations on the viscosity and composition of the polymerizable monomer, making it difficult to impart sufficient mechanical properties.

[0007] Patent Document 3 discloses a method for producing a dental cutting resin blank by dispersing a polymerizable monomer and an inorganic filler, stirring under a vacuum atmosphere to obtain granular powder, and then compressing and molding the obtained powder. This manufacturing method allows for the layering and molding of granular powders of different colors, and it is shown that a dental cutting resin blank with excellent gradation can be produced. However, this method makes it difficult to obtain uniform granular powder, resulting in a dental cutting resin blank with uneven density, poor appearance, susceptibility to cracks and fractures, and inability to provide sufficient mechanical strength. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 10-323353 [Patent Document 2] International Publication No. 2014 / 021343 [Patent Document 3] Japanese Patent Publication No. 2023-035918 [Overview of the project] [Problems that the invention aims to solve]

[0009] While several methods for manufacturing dental cutting resin blanks have been demonstrated in the conventional technology, these methods have limitations on the polymerizable monomers that can be used, making it difficult to impart sufficient mechanical strength, and also present challenges in terms of manufacturing stability. Therefore, the present invention aims to provide a dental cutting resin blank that is highly versatile, productive, and possesses high mechanical strength. [Means for solving the problem]

[0010] The inventors of the present invention investigated a method for manufacturing a resin blank for dental cutting that offers excellent productivity, can be easily manufactured regardless of the composition and components of the polymerizable monomer, and provides sufficient mechanical strength. As a result, they found that the aforementioned problems can be improved by molding a granular powder impregnated with a polymerizable monomer into at least one type of porous inorganic filler, and then polymerizing and curing it. The details of the present invention are described below.

[0011] In other words, the present invention provides a method for manufacturing a resin blank for dental cutting, comprising the steps of: (1) contacting a polymerizable monomer with at least one porous inorganic filler; (2) impregnating the porous inorganic filler with the polymerizable monomer to obtain a granular powder; and (3) placing the granular powder into a mold and curing it by applying pressure and heating.

[0012] In this invention, the specific surface area of ​​the porous inorganic filler is 10 to 300 m². 2 It can be expressed as / g.

[0013] In the present invention, the pore volume of the porous inorganic filler can be 0.01 to 0.20 cc / g.

[0014] In the present invention, the step (2) of impregnating a porous inorganic filler with a polymerizable monomer to produce granular powder can be carried out under a vacuum atmosphere. [Effects of the Invention]

[0015] After contacting at least one kind of porous inorganic filler with a polymerizable monomer, impregnating the porous inorganic filler with the polymerizable monomer to obtain granular powder, putting the granular powder into a mold, and discharging and curing a part or all of the polymerizable monomer encapsulated in the granular powder during pressurization and heating, a dental cutting resin blank excellent in versatility and productivity and having sufficient mechanical strength can be manufactured.

Mode for Carrying Out the Invention

[0016] The details of the present invention will be described below. The method for producing a dental cutting resin of the present invention includes a step (1) of contacting at least one kind of porous inorganic filler with a polymerizable monomer, a step (2) of impregnating the porous inorganic filler with the polymerizable monomer to obtain granular powder, and a step (3) of putting the granular powder into a mold, pressurizing and heating to cure it. It is a method for producing a dental cutting resin blank characterized by including these steps.

[0017] At least one kind of porous inorganic filler used in the dental cutting resin blank of the present invention indicates an inorganic filler having at least one or more pores. The presence or absence of pores in the inorganic filler can be measured by, for example, a gas adsorption method or a mercury intrusion method. More specifically, the porous inorganic filler in the present invention refers to one having a pore volume measured by the gas adsorption method of 0.001 cc / g or more.

[0018] The shape of the porous inorganic filler in the present invention is not particularly limited, and spherical, amorphous (for example, needle-like, plate-like, crushed, scaly, etc.) ones can be used. In particular, by making the shape of the porous inorganic filler spherical, a high specific surface area and pore volume can be imparted, and it can be made easy to impregnate with the polymerizable monomer. Further, by using a spherical porous inorganic filler, excellent surface lubricity can be imparted to the dental cutting resin blank, and furthermore, high mechanical strength can be imparted.

[0019] The shape of the porous inorganic filler can be defined by the circularity. In the present invention, those with a circularity of 0.8 or more are referred to as spherical, and those with a circularity of less than 0.8 are referred to as amorphous.

[0020] The circularity can be determined based on the projected area of the particles and its perimeter length obtained by observing the inorganic filler with a scanning electron microscope (SEM) and processing the observed image with an image analyzer. If the projected area of the inorganic filler obtained by image processing is S and the perimeter length of the particles is L, [Equation 1] Circularity = (4·π·S) / (L 2 ) is. By averaging the values with a sample number of 100 or more, a reproducible substantial constant value can be obtained.

[0021] The 50% particle size of the porous inorganic filler in the present invention can be 0.01 to 50 μm, and can be 0.1 to 10 μm. The 50% particle size can be measured by a general laser diffraction particle size analyzer. When the 50% particle size exceeds 50 μm, the mechanical strength of the obtained resin blank for dental cutting processing decreases, and the surface smoothness may easily decrease. Also, when the 50% particle size is less than 0.01 μm, the specific surface area and pore volume of the porous inorganic filler become excessive, the inorganic filling amount of the resin blank for dental cutting processing decreases, and the mechanical strength may easily decrease.

[0022] The specific surface area of the porous inorganic filler in the present invention can be 10 to 300 m 2 / g, and can be 20 to 250 m 2 / g. Also, the pore volume of the porous inorganic filler can be 0.01 to 0.20 cc / g, and can be 0.05 to 0.15 cc / g. The specific surface area and pore volume can be measured by a general nitrogen adsorption method. By using a porous inorganic filler having these characteristics, the polymerizable monomer can easily penetrate into the pores, enabling easy production of granular particles.

[0023] If the specific surface area and / or pore volume are too small, it may be difficult to produce uniform granular particles. Conversely, if the specific surface area and / or pore volume are too large, an excessive amount of polymerizable monomer is required for the inorganic filler, which can reduce the amount of inorganic filler in dental cutting resin blanks and potentially lead to a decrease in mechanical strength.

[0024] The components of the porous inorganic filler in the present invention are not limited to any known composition commonly used in the field of dental materials. Among these, silicon dioxide and an oxide containing at least one metal element may be included. Specifically, the porous inorganic filler in the present invention can be substantially composed of silicon dioxide and an oxide containing at least one metal element. In the present invention, substantially composing the porous inorganic filler of silicon dioxide and an oxide containing at least one metal element means allowing for the presence of unavoidable impurities other than silicon dioxide and the oxide containing at least one metal element. The at least one metal element can be any metal element such as Al, Ba, Bi, Ca, Ce, Co, Cu, Er, Fe, Hf, Ho, In, La, Mg, Mn, Nd, Ni, Pb, Sb, Sn, Sr, Ta, Ti, Y, Yb, Zn, or Zr. Specific examples of metal oxides include those of Al, Ba, Ca, Co, Cu, Fe, Hf, La, Mg, Ni, Sr, Ti, Zn, and Zr. Furthermore, by selecting oxides of metal elements with relatively large atomic numbers, it is possible to impart radiopaqueness to dental cutting resin blanks and to easily match the refractive index with polymerizable monomers.

[0025] The oxides containing at least one metal element in the porous inorganic filler can be 1 to 80 wt% in terms of oxide equivalent, and more specifically, 3 to 50 wt%. If the oxides containing at least one metal element in the porous inorganic filler are less than 1 wt% or more than 80 wt%, it may be difficult to adjust the refractive index with respect to the polymerizable monomer.

[0026] In this invention, in addition to porous inorganic fillers, other commonly used and known inorganic fillers can be used in combination as other inorganic fillers. By incorporating other inorganic fillers, the amount of inorganic filler in the dental cutting resin blank can be increased, thereby improving mechanical strength.

[0027] Other inorganic fillers used in this invention can be specifically exemplified by silica, aluminum silicate, alumina, titania, zirconia, various types of glass (including fluorine glass, borosilicate glass, soda glass, barium glass, barium aluminum silica glass, strontium glass, zirconium-containing glass, glass ceramics, fluoroaluminosilicate glass, and synthetic glass produced by the sol-gel method), Aerosil®, calcium fluoride, strontium fluoride, calcium carbonate, kaolin, clay, mica, aluminum sulfate, calcium sulfate, barium sulfate, titanium dioxide, calcium phosphate, hydroxyapatite, calcium hydroxide, strontium hydroxide, zeolite, and the like.

[0028] Other inorganic fillers can be of any shape, such as spherical or irregular (needle-shaped, plate-shaped, crushed, or flaky). In particular, irregular-shaped inorganic fillers, i.e., needle-shaped, plate-shaped, crushed, or flaky, can suppress crack propagation and improve the mechanical strength of dental cutting resin blanks. The 50% particle size of other inorganic fillers can be appropriately selected depending on the purpose, for example, from 0.01 to 100 μm or from 0.1 to 10 μm. If the 50% particle size of other inorganic fillers is less than 0.01 μm, the specific surface area may be excessive, which may reduce the amount of inorganic filler. Also, if the particle size exceeds 100 μm, it may become a starting point for fracture, which may reduce the mechanical strength.

[0029] In the present invention, the total amount of inorganic filler, including porous inorganic filler and other inorganic fillers, in the dental cutting resin blank can be set without particular limitations. Considering the physical properties, the amount of inorganic filler in the dental cutting resin blank can be 20 to 99% by weight, or 40 to 90% by weight. If the amount of inorganic filler in the dental cutting resin blank is less than 20% by weight, sufficient mechanical properties and hardness may not be imparted. Conversely, if the amount of inorganic filler exceeds 99% by weight, it may result in brittleness and insufficient mechanical strength.

[0030] In the present invention, the ratio of porous inorganic filler to other inorganic fillers in a dental cutting resin blank is preferably 100:0 to 1:99 by weight, and more preferably 90:10 to 10:90. If the amount of porous inorganic filler is too small compared to the other inorganic fillers, it may become difficult to produce granular particles.

[0031] In the present invention, the inorganic filler (porous inorganic filler and other inorganic filler) is preferably surface-treated to improve its compatibility with polymerizable monomers. There are no particular restrictions on the surface treatment method, but general silane treatment or plasma treatment can be selected depending on the purpose. Among these, it is preferable to use a treatment material such as a silane coupling material, a titanate coupling material, or an aluminate coupling material for surface treatment. Examples of silane coupling materials include γ-methacryloxypropyltrimethoxysilane and γ-methacryloxypropyltriethoxysilane. Preferably, γ-methacryloxypropyltrimethoxysilane is used.

[0032] The polymerizable monomer of the present invention is not particularly limited, and for example, known polymerizable monomers commonly used in the field of dental materials can be used. Examples of polymerizable monomers include general radical polymerizable monomers, and polymerizable monomers having an acryloyl group and / or a methacryloyl group can be preferably used. Specific examples are as follows.

[0033] Examples of monofunctional polymerizable monomers include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, allyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, meth Examples include (meth)acrylic acid esters such as xypolyethylene glycol (meth)acrylate, glycerol (meth)acrylate, and isobonyl (meth)acrylate; silane compounds such as γ-(meth)acryloyloxypropyltrimethoxysilane and γ-(meth)acryloyloxypropyltriethoxysilane; and nitrogen-containing compounds such as 2-(N,N-dimethylamino)ethyl (meth)acrylate, N-methylol (meth)acrylamide, and diacetone (meth)acrylamide.

[0034] Furthermore, difunctional polymerizable monomers include, for example, diol di(meth)acrylates such as ethylene diol di(meth)acrylate, propylenediol di(meth)acrylate, propanediol di(meth)acrylate, butanediol di(meth)acrylate, hexanediol di(meth)acrylate, octanediol di(meth)acrylate, nonanediol di(meth)acrylate, decanediol di(meth)acrylate, and eicosanediol di(meth)acrylate; and glycol di(meth)acrylates such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, and neopentyl glycol di(meth)acrylate. Polyurethane polymerizable monomers derived from adducts of vinyl monomers having hydroxyl groups, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 3-chloro-2-hydroxypropyl (meth)acrylate, with diisocyanate compounds such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, diisocyanate methylcyclohexane, isophorone diisocyanate, and methylbis(4-cyclohexyl isocyanate); (meth)acrylate polymerizable monomers having aromatic rings and urethane bonds derived from adducts of vinyl monomers having hydroxyl groups, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 3-chloro-2-hydroxypropyl (meth)acrylate, with aromatic ring-containing diisocyanate compounds such as diisocyanate methylbenzene and 4,4'-diphenylmethane diisocyanate;2,2-bis((meth)acryloxyphenyl)propane, 2,2-bis[4-(3-(meth)acryloxy)-2-hydroxypropoxyphenyl]propane, 2,2-bis(4-(meth)acryloxyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxytetraethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxypentaethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxypolyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxydipropoxyphenyl)propane, 2-(4-(meth)acryloxyethoxyphenyl)-2-(4-(meth)acryloxyphenyl) Examples include polymerizable (meth)acrylate monomers having aromatic rings and ether links, such as propane, 2-(4-(meth)acryloxydiethoxyphenyl)-2-(4-(meth)acryloxytriethoxyphenyl)propane, 2-(4-(meth)acryloxydipropoxyphenyl)-2-(4-(meth)acryloxytriethoxyphenyl)propane, and 2,2-bis(4-(meth)acryloxyisopropoxyphenyl)propane; 1:2 reaction products of bisphenol A or hydrogenated bisphenol A and glycidyl (meth)acrylate, such as bisphenol A diglycidyl ether (meth)acrylic acid adducts, and 1:2 adducts of bisphenol A or hydrogenated bisphenol A and (meth)acrylate having an epoxy group.

[0035] Furthermore, examples of polyfunctional polymerizable monomers having three or more polymerizable functional groups include trimethylolmethanetri(meth)acrylate, trimethylolethanetri(meth)acrylate, trimethylolpropanetri(meth)acrylate, pentaerythritoltetra(meth)acrylate, tri(meth)acrylate with a phosphazene skeleton, tri(meth)acrylate with an isocyanuric acid skeleton, pentaerythritoltetra(meth)acrylate, ditrimethylolpropanetetra(meth)acrylate, and other tri(meth)acrylates. Diisocyanate and tetra(meth)acrylate, as well as urethane polymerizable monomers derived from diisocyanate compounds such as diisocyanate methylbenzene, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, diisocyanate methylcyclohexane, isophorone diisocyanate, and methylbis(4-cyclohexyl isocyanate) and vinyl monomers having hydroxyl groups such as glycidol di(meth)acrylate, dipentaerythritol hydro Polymerizable monomers having five or more ethylenically unsaturated groups, such as xypenta(meth)acrylate; polymerizable polyfunctional acrylates containing polyethylene unsaturated carbamoyl isocyanurates; phenyl glycidyl ether acrylate hexamethylene diisocyanate urethane prepolymer; phenyl glycidyl ether toluene diisocyanate urethane prepolymer; pentaerythritol triacrylate toluene diisocyanate urethane prepolymer; and pentaerythritol triacrylate isophorone diisocyanate. Polymerizable polyfunctional acrylates having urethane bonds, such as urethane prepolymers; examples include ditrimethylolpropanetetraacrylate, ethoxylated pentaerythritol tetraacrylate, propoxylated pentaerythritol tetraacrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and trimethylpropanetri(meth)acrylate.

[0036] In this invention, the aforementioned polymerizable monomers can be used individually or in combination of two or more. By mixing two or more polymerizable monomers, the refractive index, viscosity, and other properties of the polymerizable monomers can be adjusted as appropriate. The amount of polymerizable monomers can be 1 to 80% by weight or 10 to 60% by weight relative to the dental cutting resin blank. If the amount of polymerizable monomers is less than 1% by weight, it becomes difficult to obtain uniform granular particles, which tends to lead to a decrease in mechanical strength. Also, if the amount of polymerizable monomers exceeds 80% by weight, it may not be possible to impart sufficient mechanical properties or hardness.

[0037] In this invention, it is preferable to incorporate a polymerization initiator and the like for the purpose of polymerization and curing. The type of polymerization initiator can be used without particular limitations, but a thermal polymerization catalyst that decomposes with heat and generates radicals can be used.

[0038] Effective thermal polymerization catalysts include, for example, diacyl peroxides, peroxyesters, dialkyl peroxides, peroxyketals, ketone peroxides, and hydroperoxides. Specifically, examples of diacyl peroxides include benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, and m-toluyl peroxide.

[0039] The amount of polymerization catalyst used can be 0.01 to 5 parts by weight, or 0.05 to 3 parts by weight, per 100 parts by weight of polymerizable monomer. If the amount of polymerization catalyst is less than 0.01 parts by weight, polymerization of the polymerizable monomer may be insufficient, making it difficult to impart sufficient mechanical strength. Furthermore, if the amount of polymerization catalyst exceeds 5 parts by weight, cracks or fractures may occur in the blank after molding.

[0040] In this invention, uniform polymerization and curing can also be achieved by incorporating a chain transfer agent into the polymerizable monomer. Any known compound can be used as the chain transfer agent without limitation. Specifically, examples include mercaptan compounds such as n-butyl mercaptan and n-octyl mercaptan, terpenoid compounds such as limonene, myrcene, α-terpinene, β-terpinene, γ-terpinene, terpinolene, β-tepinene, and α-tepinene, and α-methylstyrene dimer. Among these chain transfer agents, terpenoid compounds are particularly preferred. Specifically, α-terpinene, β-terpinene, and γ-terpinene are more preferred. The amount of chain transfer agent can be 0.001 to 1 part by weight, or 0.1 to 0.5 parts by weight, per 100 parts by weight of polymerizable monomer. If the amount of chain transfer agent is less than 0.001 parts by weight, cracks or fractures may occur during molding. Furthermore, if the amount of chain transfer agent exceeds 1 part by weight, the polymerizable monomer may not polymerize sufficiently.

[0041] The viscosity of the binder resin containing the polymerizable monomer and polymerization catalyst of the present invention is not particularly limited, but it can be set to a viscosity that allows impregnation into the pores of the porous inorganic filler. The viscosity of the binder resin can be measured with a general rotational viscometer, for example, a B-type viscometer can be used. The viscosity of the binder resin can be 0.01 to 1000 Pa·s (23°C) or 0.1 to 800 Pa·s (23°C). If the viscosity of the binder resin is less than 0.01 Pa·s, the mechanical strength of the binder resin tends to be low, which may reduce the mechanical properties of the dental cutting resin blank. Also, if it exceeds 1000 Pa·s, the binder resin becomes less likely to impregnate into the pores of the porous inorganic filler, leading to a decrease in the amount of inorganic filler, which may also reduce the mechanical properties of the dental cutting resin blank.

[0042] The dental cutting resin blank of the present invention may contain a coloring agent for the purpose of imparting a color similar to that of natural teeth. Any known coloring agent can be used without limitation, and both inorganic compound-based and organic compound-based coloring agents can be used.

[0043] The dental cutting resin blank of the present invention may also contain known organic fillers as needed. Examples of organic fillers include polymethyl methacrylate (PMMA), polyethyl methacrylate, polypropyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyethylene glycol, polypropylene glycol, and polyvinyl alcohol. Examples of organic composite fillers include those obtained by polymerizing and coating the surface of an inorganic filler with a polymerizable monomer and then grinding it to an appropriate particle size, or particles obtained by polymerizing and grinding a polymerizable monomer mixed with an inorganic filler beforehand.

[0044] The dental cutting resin material of the present invention may contain various known additives as needed. Examples of additives include polymerization inhibitors, discoloration inhibitors, fluorescent agents, ultraviolet absorbers, and antibacterial agents, which can be appropriately added depending on the purpose.

[0045] In the present invention, the specific embodiment used in step (1) of contacting a polymerizable monomer with an inorganic filler is not particularly limited, and there is no problem as long as the polymerizable monomer and the inorganic filler containing a porous inorganic filler can be brought into contact.

[0046] In step (1), the polymerizable monomer and the inorganic filler can be brought into contact and kneaded together to form a dispersed state. The method of bringing the polymerizable monomer and the inorganic filler into contact is not particularly limited; for example, the inorganic filler may be added on top of the pre-weighed polymerizable monomer, or conversely, the polymerizable monomer may be added on top of the pre-weighed inorganic filler. There are no particular restrictions on the temperature or time during contact; the temperature can be appropriately set to a temperature below which the polymerization catalyst does not react, and there are no restrictions on the time as long as the polymerizable monomer and the inorganic filler are dispersed without separation. As for the kneading method, for example, methods using a magnetic stirrer, a raika, a planetary mixer, a Trimix, a twin-screw extruder, a roll pill, a centrifugal mixer, a rotary-orbit mixer, etc., can be used as appropriate. In particular, from the viewpoint of easily dispersing the inorganic filler in the polymerizable monomer, a device that can apply a high shear force can be used. In addition, dispersants and organic solvents that are commonly used for the purpose of dispersion may be added as appropriate. In this invention, a dispersed state means that the inorganic filler exists as a non-clumped or non-aggregated inorganic filler within the polymerizable monomer, without any association. There are no particular restrictions on the mixing temperature, but it can be appropriately set to a temperature below which the polymerization catalyst used does not react. There are also no particular restrictions on the mixing time; as long as the polymerizable monomer and inorganic filler are dispersed without separation, there is no problem. The rotation speed during mixing can be set arbitrarily. For example, the rotation speed can be set to 5 m / min or more in terms of the peripheral speed of rotation.

[0047] In the present invention, the specific embodiment used in step (2), in which polymerizable monomers are impregnated into an inorganic filler to obtain granular powder, is not particularly limited, and equipment can be appropriately set up according to the purpose. For example, after preparing a paste-like substance in which polymerizable monomers and inorganic filler are dispersed in step (1), the polymerizable monomers can be impregnated into the pores of the porous inorganic filler. There are no particular restrictions on the temperature and time conditions in step (2), but the temperature can be appropriately set to a temperature below which the polymerization catalyst does not react, and the time can be at least 1 second without any problems. Furthermore, the process can be carried out under an atmospheric atmosphere, a pressurized atmosphere, or a vacuum atmosphere. In particular, from the viewpoint of productivity, it is preferable to use a vacuum atmosphere. By using a vacuum atmosphere, it is possible to easily impregnate the polymerizable monomers into the pores of the porous inorganic filler.

[0048] The vacuum level in the vacuum atmosphere should be between -750 mmHg and 0 mmHg, preferably between -740 and -50 mmHg, based on gauge pressure. If the vacuum level is too high, the polymerizable monomer may vaporize. It is also preferable to set the vacuum level appropriately according to the viscosity and composition of the polymerizable monomer used.

[0049] The method used in process (2) is not particularly limited, but from the viewpoint of productivity, it is preferable to use equipment that can operate continuously from process (1).

[0050] For example, when using a planetary mixer, polymerizable monomers can be impregnated into a porous inorganic filler while dispersing the inorganic filler and polymerizable monomers. There are no particular restrictions on the conditions for dispersion and / or impregnation, but granular powder can be efficiently obtained by impregnating the inorganic filler with polymerizable monomers while stirring. The rotation speed during stirring can be set arbitrarily. The rotation speed is preferably 50 m / min or less, and more preferably 30 m / min or less, when converted to a peripheral speed of rotation speed. By setting the rotation speed appropriately, a uniform granule particle size with the desired particle size can be obtained.

[0051] Alternatively, a rotating / revolving mixer can be used. The rotation speed during stirring can be set arbitrarily. Preferably, the rotation speed is 200 m / min or less, and more preferably 150 m / min or less, when converted to a peripheral speed of rotation. By appropriately setting the rotation speed, a uniform granule size with the desired particle size can be obtained.

[0052] Steps (1) and (2) are preferably carried out with temperature control from a productivity standpoint. For example, increasing the temperature reduces the viscosity of the polymerizable monomer, making it easier to impregnate the pores of the porous inorganic filler. There are no particular restrictions on the temperature, but it can be appropriately set below the temperature at which the polymerization catalyst used does not react. For example, production can be carried out at temperatures between 30°C and 100°C. In addition, cooling the granular powder when it is removed improves handling and increases productivity. For example, production can be carried out at a cooling temperature of 30°C or lower.

[0053] The granular powder of the present invention refers to a state in which at least one porous inorganic filler is aggregated via polymerizable monomers. The particle size of the granules can be 1 to 5000 μm, or 100 to 2000 μm. The particle size of the granular powder can be measured by analyzing images taken with a general optical microscope or scanning electron microscope. If the particle size of the granular powder is less than 1 μm, internal defects such as pores may easily occur in the molded body. Also, if the particle size exceeds 5000 μm, it may worsen the workability when putting the granular powder into a mold.

[0054] In the present invention, step (3), in which granular powder is placed in a mold and hardened by pressurization and heating, is acceptable as long as it can be molded into the desired shape, but from the viewpoint of productivity, it is preferable to perform it by press molding. One example of a press molding method is to fill a press mold of the desired size with granular powder and pressurize it by uniaxial pressing using upper and lower punches. The press pressure at this time can be appropriately set depending on the size of the target molded body, the type of granular powder, and the particle size. The press pressure can be 1 MPa or more in terms of surface pressure, and can be 5 MPa or more. If the press pressure is too low, the granular powder will not be densely packed, which may cause defects inside the dental cutting resin blank.

[0055] Another method of press molding according to the present invention is cold isostatic pressing (CIP). Generally, CIP molding can apply higher press pressure than uniaxial pressing and can apply uniform pressure to the molded body from three dimensions, thus enabling uniform molding of granular powder.

[0056] The heating temperature in step (3) is not particularly limited as long as it is a temperature at which the polymerizable monomer can be polymerized and cured, and can be set appropriately depending on the type of polymerization catalyst used.

[0057] In the present invention, step (3) of pressurizing and heating to cure may be performed simultaneously with pressurizing, or the pre-molded body may be press-molded without continuous heating, and then heated again to cure. As a method for manufacturing a dental cutting resin blank via a pre-molded body, for example, a pre-molded body may be formed by placing granular powder in a mold and uniaxial press molding at room temperature, then the pre-molded body may be cut to the desired size of the mold, and polymerized and cured by press molding while heating.

[0058] In this invention, granular powders of different compositions and colors can be appropriately placed in a mold and layered. For example, by pre-producing granular powders of different colors, layering each powder in a mold, and then pressurizing and curing them, a dental cutting resin blank with a gradation similar to that of natural teeth can be manufactured. [Examples]

[0059] The present invention will be described in more detail and specifically below with reference to examples, but the present invention is not limited thereto.

[0060] [Bending strength test] Objective: To evaluate the mechanical strength (flexural strength) of resin blanks for dental cutting. Method: Plates measuring (1.2±0.2)×(4.0±0.2)×14mm or larger were cut from the prototype dental cutting resin blanks, and the surfaces were polished with #2000 grit waterproof sandpaper. These were immersed in distilled water in a sealed container and stored at 37°C for one day before being used as test specimens. Bending strength was measured using an Instron universal testing machine (Instron 5567, manufactured by Instron Corporation) with a support distance of 12mm and a crosshead speed of 1mm / min.

[0061] [Evaluation of cracks and fissures in molded products] Objective: Evaluation of cracking and fracture in resin blanks for dental cutting. Method: Ten molded dental cutting resin blanks were visually inspected to evaluate the presence or absence of cracks and fractures. The evaluation was as follows: ○: No cracks or fractures, ×: One or more cracks or fractures present.

[0062] [Evaluation of air bubbles in molded products] Objective: Evaluation of air bubbles in resin blanks for dental cutting. Method: Using an X-ray transmission device (SMX-31M, Shimadzu Corporation), fluoroscopic images were taken of 10 molded dental cutting resin blanks, and the presence or absence of air bubbles was evaluated visually from these images. The evaluation was as follows: ○: No air bubbles larger than 1 mm; △: 1 to 3 air bubbles larger than 1 mm; ×: 4 or more air bubbles larger than 1 mm.

[0063] [Particle circularity] The shape of the particles was confirmed from the images taken by a scanning electron microscope (JMS-6390LA, manufactured by JEOL Ltd.). The circularity was determined by processing the SEM images with an image analyzer. The number of samples for image processing was set to 100 or more. When the area of the particles obtained by image processing was S and the perimeter length of the particles was L, the circularity was calculated as (4·π·S) / (L2).

[0064] [Porous inorganic filler] PF-1: Porous inorganic filler 1 (Shape: spherical, Circularity: 0.85, Composition: zirconium silicate (zirconium oxide equivalent: 15 wt%), Specific surface area: 32 m 2 / g, Pore volume: 0.11 cc / g, 50% particle diameter: 2.5 μm) PF-2: Porous inorganic filler 2 (Shape: spherical, Circularity: 0.84, Composition: zirconium silicate (zirconium oxide equivalent: 18 wt%), Specific surface area: 130 m 2 / g, Pore volume: 0.20 cc / g, 50% particle diameter: 2.9 μm) PF-3: Porous inorganic filler 3 (Shape: spherical, Circularity: 0.87, Composition: zirconium silicate (zirconium oxide equivalent: 17 wt%), Specific surface area: 20 m 2 / g, Pore volume: 0.06 cc / g, 50% particle diameter: 2.4 μm) PF-4: Porous inorganic filler 4 (Shape: spherical, Circularity: 0.89, Composition: zirconium silicate (zirconium oxide equivalent: 1 wt%), Specific surface area: 206 m 2 / g, Pore volume: 0.81 cc / g, 50% particle diameter: 10.5 μm) PF-5: Porous inorganic filler 5 (Shape: spherical, Circularity: 0.81, Composition: strontium silicate (strontium oxide equivalent: 15 wt%), Specific surface area: 35 m 2 / g, Pore volume: 0.12 cc / g, 50% particle diameter: 2.3 μm) PF-6: Porous inorganic filler 6 (Shape: irregular, Circularity: 0.65, Composition: zirconium silicate (zirconium oxide equivalent: 18 wt%), Specific surface area: 3 m 2 / g, Pore volume: 0.01 cc / g, 50% particle diameter: 3.1 μm) PF-7: Porous inorganic filler 7 (Shape: Irregular, Circularity: 0.70, Composition: Zirconium silicate (equivalent to zirconium oxide: 16 wt%), Specific surface area: 91 m²) 2 (per g, pore volume: 0.17 cc / g, 50% particle size: 9.5 μm) PF-8: Porous inorganic filler 7 (Shape: Spherical, Circularity: 0.90, Composition: Zirconium silicate (equivalent to zirconium oxide: 16 wt%), Specific surface area: 19 m²) 2 (per g, pore volume: 0.06 cc / g, 50% particle size: 2.2 μm)

[0065] [Other inorganic fillers] NF-1:UF0.4 (Shape: Irregular, Composition: Strontium glass, Specific surface area: 21 m²) 2 ( / g, 50% particle size: 0.4 μm, manufactured by Schott) Aerosil R-972 (Shape: Irregular (aggregate), Composition: Silica, Primary particle size: 16 nm, Specific surface area: 120 m²) 2 (Manufactured by Aerosil)

[0066] [Surface treatment material] γ-MPS: γ-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)

[0067] [polymerizable monomers] UDMA: 2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl ) Dimethacrylate BP-2EM: Dimethacrylate, an EO adduct of bisphenol A. TEGDMA: Triethylene glycol dimethacrylate

[0068] [Polymerization catalyst] BPO: Benzoyl peroxide DMBH: 2,5-dimethyl-2,5-di(t-butylperoxy)hexane

[0069] [Chain transfer material] α-Terpinene:p-Mentha-1,3-diene (manufactured by Tokyo Chemical Industry Co., Ltd.) γ-Terpinene:p-Mentha-1,4-diene (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0070] A binder resin was prepared using the above polymerizable monomer, polymerization catalyst, and chain transfer agent.

[0071] [Preparation of Binder Resin 1] Binder resin (B1) was prepared by mixing 70 parts by weight of UDMA, 30 parts by weight of TEGDMA, 0.5 parts by weight of BPO, and 0.1 parts by weight of α-terpinene. The viscosity of binder resin (B1) was 0.3 Pa·s (23℃).

[0072] [Preparation of Binder Resin 2] Binder resin (B2) was prepared by mixing 100 parts by weight of BP-2EM, 0.5 parts by weight of DMBH, and 0.3 parts by weight of γ-terpinene. The viscosity of binder resin (B2) was 1.4 Pa·s (23℃).

[0073] [Preparation of Binder Resin 3] Binder resin (B3) was prepared by mixing 100 parts by weight of BP-2EM, 5 parts by weight of DMBH, and 1 part by weight of α-terpinene. The viscosity of binder resin (B3) was 1.2 Pa·s (23℃).

[0074] [Preparation of Binder Resin 4] Binder resin (B4) was prepared by mixing 100 parts by weight of UDMA and 0.5 parts by weight of DMBH. The viscosity of binder resin (B4) was 10.8 Pa·s (23℃).

[0075] [Example 1] A porous inorganic filler (PF-1) (100 parts by weight) was surface-treated with γ-MPS (6 parts by weight). 78 parts by weight of the surface-treated filler and 22 parts by weight of binder resin (B1) were mixed and dispersed using a double planetary mixer. The mixing tank was then subjected to a vacuum atmosphere (vacuum level: -700 mmHg) and stirred (rotation speed: 5 m / min) until a granular powder (particle size: 572 μm) was obtained. The obtained granular powder was filled into a mold (14.5 mm × 14.5 mm × 18.0 mm) and polymerized and cured by uniaxial press molding (surface pressure: 50 MPa, temperature: 130 °C) to obtain a resin blank for dental cutting.

[0076] [Example 2] A porous inorganic filler (PF-2) (100 parts by weight) was surface-treated with γ-MPS (20 parts by weight). 70 parts by weight of the surface-treated filler, 5 parts by weight of Aerosil R-972, and 25 parts by weight of binder resin (B1) were mixed and dispersed using a double planetary mixer. The mixing tank was then subjected to a vacuum atmosphere (vacuum level: -650 mmHg) and stirred (rotation speed: 10 m / min) until a granular powder (particle size: 236 μm) was obtained. A resin blank for dental cutting was then obtained in the same manner as in Example 1.

[0077] [Example 3] A porous inorganic filler (PF-3) (100 parts by weight) was surface-treated with γ-MPS (6 parts by weight). 80 parts by weight of the surface-treated filler and 20 parts by weight of binder resin (B1) were mixed and dispersed using a double planetary mixer. The mixing tank was then subjected to a vacuum atmosphere (vacuum degree: -730 mmHg) and stirred (rotation speed: 10 m / min) until a granular powder (particle size: 452 μm) was obtained. A resin blank for dental cutting was then obtained in the same manner as in Example 1.

[0078] [Example 4] A porous inorganic filler (PF-4) (100 parts by weight) was surface-treated with γ-MPS (25 parts by weight). 60 parts by weight of the surface-treated filler, 8 parts by weight of NF-1, and 32 parts by weight of binder resin (B1) were mixed and dispersed using a double planetary mixer. The mixing tank was then subjected to a vacuum (vacuum level: -600 mmHg) and stirred (rotation speed: 10 m / min) until a granular powder (particle size: 942 μm) was obtained. A dental cutting resin blank was then obtained in the same manner as in Example 1.

[0079] [Example 5] A porous inorganic filler (PF-4) (100 parts by weight) was surface-treated with γ-MPS (25 parts by weight). The surface-treated filler (8 parts by weight), NF-1 (71 parts by weight), and binder resin (B1) (21 parts by weight) were mixed and dispersed using a double planetary mixer. The mixing tank was then subjected to a vacuum atmosphere (vacuum level: -600 mmHg) and stirred until a granular powder (particle size: 628 μm) was obtained. The obtained granular powder was filled into a mold (14.5 mm × 14.5 mm × 18.0 mm) and polymerized and cured by uniaxial press molding (surface pressure: 1 MPa, temperature: 150 °C) to obtain a resin blank for dental cutting.

[0080] [Example 6] A porous inorganic filler (PF-1) (100 parts by weight) was surface-treated with γ-MPS (6 parts by weight). 55 parts by weight of the surface-treated filler, 23 parts by weight of NF-1, and 22 parts by weight of binder resin (B2) were mixed and dispersed using a double planetary mixer. The mixing tank was then subjected to a vacuum atmosphere (vacuum level: -700 mmHg) and stirred (rotation speed: 9 m / min) until a granular powder (average particle size: 292 μm) was obtained. The obtained granular powder was filled into a mold (14.5 mm × 14.5 mm × 18.0 mm) and polymerized and cured by uniaxial press molding (surface pressure: 50 MPa, temperature: 150 °C) to obtain a resin blank for dental cutting.

[0081] [Example 7] A porous inorganic filler (PF-2) (100 parts by weight) was surface-treated with γ-MPS (20 parts by weight). 75 parts by weight of the surface-treated filler and 25 parts by weight of binder resin (B2) were mixed and dispersed using a double planetary mixer. The mixture was then stirred in an air atmosphere (rotation speed: 12 m / min) until a granular powder (average particle size: 1492 μm) was obtained. A resin blank for dental cutting was then obtained in the same manner as in Example 6.

[0082] [Example 8] A porous inorganic filler (PF-1) (100 parts by weight) was surface-treated with γ-MPS (6 parts by weight). 55 parts by weight of the surface-treated filler, 23 parts by weight of NF-1, and 22 parts by weight of binder resin (B2) were mixed and dispersed using a double planetary mixer. The mixing tank was then subjected to a vacuum atmosphere (vacuum level: -700 mmHg) and stirred (rotation speed: 5 m / min) until a granular powder (average particle size: 292 μm) was obtained. A resin blank for dental cutting was then obtained in the same manner as in Example 6.

[0083] [Example 9] A porous inorganic filler (PF-2) (100 parts by weight) was surface-treated with γ-MPS (20 parts by weight). 75 parts by weight of the surface-treated filler and 25 parts by weight of binder resin (B2) were mixed in a mixing tank using a rotary-orbit mixer (Awatori Rentaro) in an atmospheric environment (rotation speed: 188 m / min) until a granular powder (average particle size: 855 μm) was obtained. After that, a resin blank for dental cutting was obtained in the same manner as in Example 6.

[0084] [Example 10] A porous inorganic filler (PF-5) (100 parts by weight) was surface-treated with γ-MPS (10 parts by weight). 75 parts by weight of the surface-treated filler and 25 parts by weight of binder resin (B2) were mixed and dispersed using a double planetary mixer. The mixing tank was then subjected to a vacuum atmosphere (vacuum level: -700 mmHg) and stirred (rotation speed: 10 m / min) until a granular powder (average particle size: 650 μm) was obtained. The obtained granular powder was filled into a mold (14.5 mm × 14.5 mm × 18.0 mm) and polymerized and cured by uniaxial press molding (surface pressure: 10 MPa, temperature: 150 °C) to obtain a resin blank for dental cutting.

[0085] [Example 11] A porous inorganic filler (PF-6) (100 parts by weight) was surface-treated with γ-MPS (1 part by weight). 90 parts by weight of the surface-treated filler and 10 parts by weight of binder resin (B4) were mixed and dispersed using a double planetary mixer. The mixing tank was then subjected to a vacuum (vacuum level: -700 mmHg) and stirred (rotation speed: 10 m / min) until a granular powder (average particle size: 650 μm) was obtained. A resin blank for dental cutting was then obtained in the same manner as in Example 6.

[0086] [Example 12] A porous inorganic filler (PF-7) (100 parts by weight) was surface-treated with γ-MPS (20 parts by weight). 65 parts by weight of the surface-treated filler and 35 parts by weight of binder resin (B1) were mixed and dispersed using a double planetary mixer. The mixing tank was then subjected to a vacuum (vacuum level: -700 mmHg) and stirred (rotation speed: 3 m / min) until a granular powder (average particle size: 2100 μm) was obtained. A resin blank for dental cutting was then obtained in the same manner as in Example 1.

[0087] [Example 13] A porous inorganic filler (PF-8) (100 parts by weight) was surface-treated with γ-MPS (6 parts by weight). 75 parts by weight of the surface-treated filler and 25 parts by weight of binder resin (B3) were mixed and dispersed using a double planetary mixer. The mixing tank was then subjected to a vacuum (vacuum level: -700 mmHg) and stirred (rotation speed: 30 m / min) until a granular powder (average particle size: 90 μm) was obtained. A resin blank for dental cutting was then obtained in the same manner as in Example 6.

[0088] [Comparative Example 1] Other inorganic filler material (NF-1) (100 parts by weight) was surface-treated with γ-MPS (6 parts by weight). 75 parts by weight of the surface-treated filler and 25 parts by weight of binder resin (B1) were mixed and dispersed using a double planetary mixer to obtain a paste. The obtained paste was filled into a mold (14.5 mm × 14.5 mm × 18.0 mm) and polymerized and cured by uniaxial press molding (surface pressure: 50 MPa, temperature: 100 °C) to obtain a resin blank for dental cutting.

[0089] [Comparative Example 2] A porous inorganic filler (PF-4) (100 parts by weight) was surface-treated with γ-MPS (25 parts by weight). 60 parts by weight of the surface-treated filler, 8 parts by weight of NF-1, and 32 parts by weight of binder resin (B1) were mixed and dispersed using a double planetary mixer to obtain a paste. The obtained paste was filled into a mold (14.5 mm × 14.5 mm × 18.0 mm) and polymerized and cured by uniaxial press molding (surface pressure: 50 MPa, temperature: 100 °C) to obtain a resin blank for dental cutting.

[0090] [Table 1]

[0091] The results above demonstrate that the dental cutting resin blank of the present invention is free from cracks, fissures, and air bubbles, and provides high mechanical strength. Therefore, the dental cutting resin blank of the present invention is considered to be a method for manufacturing a dental cutting resin blank that is excellent in versatility and productivity, and can also provide high mechanical strength.

[0092] In this specification, where a component of the invention is described as either one or more, or without being limited to either one or more, such component may be either one or more, unless the context should be otherwise interpreted.

[0093] Although the present invention has been described with reference to detailed embodiments, those skilled in the art will understand that various changes or modifications are possible based on the matters disclosed herein. Accordingly, the scope of embodiments of the present invention is intended to include any changes or modifications. [Industrial applicability]

[0094] According to the present invention, it is possible to manufacture a resin blank for dental cutting that is highly versatile and productive, and also possesses high mechanical strength.

Claims

1. A method for manufacturing a resin blank for dental cutting, wherein the manufacturing method is: A step (1) of contacting a polymerizable monomer with at least one porous inorganic filler, (2) A step of impregnating the porous inorganic filler with a polymerizable monomer to obtain granular powder, The process (3) involves placing the granular powder into a mold and hardening it by applying pressure and heating, A method for manufacturing a dental cutting resin blank, characterized by including [a specific component].

2. The specific surface area of ​​the porous inorganic filler is 10 to 300 m². ２ A method for manufacturing a dental cutting resin blank according to claim 1, characterized in that the amount is / g.

3. The method for producing a dental cutting resin blank according to claim 1, characterized in that the pore volume of the porous inorganic filler is 0.01 to 0.20 cc / g.

4. The method for producing a dental cutting resin blank according to claim 2, characterized in that the pore volume of the porous inorganic filler is 0.01 to 0.20 cc / g.

5. A method for producing a dental cutting resin blank according to any one of claims 1 to 4, characterized in that the step (2) of impregnating the porous inorganic filler with a polymerizable monomer to produce a granular powder is performed under a vacuum atmosphere.

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