JP7405909B2 - dental mill blank - Google Patents

Description

The present invention relates to a dental mill blank, a method for manufacturing the same, and a method for manufacturing a dental prosthesis using the same. In more detail, for example, inlays, onlays, veneers, crowns, bridges, abutment teeth, dental posts, dentures, denture bases, implant parts (fixtures, abutments) are manufactured by cutting using a dental CAD/CAM system. The present invention relates to a dental mill blank that can be suitably used for manufacturing dental prostheses such as, a method for manufacturing the same, and a method for manufacturing a dental prosthesis using the same.

In recent years, CAD/CAM systems have become popular, in which dental prostheses such as inlays and crowns are designed using a computer and manufactured by cutting using a milling device. The mill blank, which is the material to be cut used in the CAD/CAM system, consists of a prismatic mill blank part (block body) that is used for cutting, and a part that protrudes from the mill blank part and is used to fix the mill blank to the milling device. There are some that include a supporting part.

In crown orthodontic restoration treatment, it is required to provide an appearance as close to the color tone of natural teeth as possible. However, mill blanks having a mill blank portion made of a single component often cannot fully satisfy the above aesthetic requirements. In order to solve such problems, a mill blank having a mill blank portion having a laminated structure in which layers of different colors are laminated has been proposed.

If a mill blank part with a laminated structure is simply laminated with each layer, the difference in color tone between the layers may become noticeable and it may not be possible to provide an appearance close to the color tone of natural teeth. Therefore, techniques for making the layer shape of the mill blank part specific have been known (see Patent Documents 1 to 3, etc.).

Special Publication No. 2011-528597 Special table 2016-535610 publication Special table 2014-534018 publication

However, conventional mill blanks with a specified layer shape contain many single layer parts that do not have a laminated structure, so the parts that will become the dental prosthesis with a laminated structure are cut out from a wide range of parts. On the other hand, if the part that will become the dental prosthesis is cut out to include a single layer part, there are problems such as limitations in milling and waste of material at the periphery. There was a problem that the compressive strength decreased in the single layer portion. In addition, there is room for improvement in the appearance of the resulting dental prosthesis, especially when the conventional mill blank has a layered shape as in Patent Document 2, which provides a natural appearance when viewed from multiple directions. There was a problem that it was difficult to reproduce color changes. Furthermore, the conventional mill blank having a mill blank portion having a laminated structure has a problem that it is complicated to industrially manufacture and tends to lead to high costs.

Therefore, the present invention makes it possible to manufacture a dental prosthesis that has an appearance closer to the color tone of natural teeth and has excellent mechanical strength, and can be cut out into a desired shape from a wide range of parts, making it easy to process. An object of the present invention is to provide a dental mill blank that has excellent properties and can be easily manufactured, a method for manufacturing the mill blank, and a method for manufacturing a dental prosthesis using the mill blank.

The present invention includes the following.
[1] A dental mill blank having a prismatic mill blank portion having a laminated structure of two or more layers, the mill blank portion having a plurality of side surfaces (P) having at least one curved interface, A mill blank, wherein at least two of the sides (P) are not parallel to each other.
[2] The mill blank according to [1], wherein the mill blank portion has four or more of the side surfaces (P).
[3] The mill blank according to [1] or [2], wherein the prismatic shape is a quadrangular prism.
[4] The mill blank according to any one of [1] to [3], wherein the two side surfaces (P) that are not parallel to each other are orthogonal to each other.
[5] Any one of [1] to [4], wherein the mill blank portion has a virtual first symmetry plane that equally divides the laminated structure, and the virtual first symmetry plane has at least one curved interface. Mill blank described in one.
[6] The mill blank portion has a virtual second symmetry plane that is perpendicular to the virtual first symmetry plane and equally divides the laminated structure, and the virtual second symmetry plane has at least one curved surface. The mill blank according to [5], which has an interface.
[7] The shape of the curvature at the interface of the side surface (P) is selected from the group consisting of a circular arc, an elliptical arc, a parabola, a catenary, and a combination of multiple of these shapes. The mill blank according to any one of [1] to [6].
[8] The mill blank according to any one of [1] to [7], wherein the adjacent layers in the laminated structure have different color tone and/or transparency.
[9] The mill blank according to any one of [1] to [8], wherein the mill blank portion has a laminated structure of four or more layers.
[10] The mill blank according to any one of [1] to [9], wherein all layers contain the inorganic filler (a).
[11] The method for producing a mill blank according to any one of [1] to [10], wherein the curved interface of the side surface (P) is formed by mechanical pressure.
[12] A method for manufacturing a dental prosthesis, comprising the step of cutting the mill blank according to any one of [1] to [10].

According to the present invention, it is possible to manufacture a dental prosthesis that has an appearance closer to the color tone of natural teeth and has excellent mechanical strength, and it is also possible to cut out a desired shape from a wide range of parts, making it easy to process. A dental mill blank that is excellent in quality and can be easily manufactured, a method for manufacturing the mill blank that allows the mill blank to be manufactured more easily, and has an appearance closer to the color tone of natural teeth. Provided is a method for manufacturing a dental prosthesis that can manufacture a dental prosthesis that also has excellent mechanical strength.

1 is a schematic diagram showing an example of an embodiment of a mill blank part according to the present invention. 1 is a perspective view schematically showing various examples of layer shapes in a mill blank part and a corresponding molded body for forming the same according to the present invention; FIG. FIG. 2 is a cross-sectional view (schematic diagram) of the mill blank part according to the present invention cut along a virtual first plane of symmetry 2. FIG. FIG. 3 is a cross-sectional view (schematic diagram) when the mill blank part according to the present invention is cut along a virtual second plane of symmetry 3; It is a schematic diagram showing the cutout position of the test piece for compressive strength measurement and the cutout position of the chromaticity plate for chromaticity measurement in Examples and Comparative Examples. FIG. 5 also shows the measurement results of compressive strength. 2 is a measurement result of chromaticity of mill blank part (1) of Example 1. 3 shows the measurement results of chromaticity of the mill blank part (2) of Example 2. 3 shows the measurement results of chromaticity of the mill blank part (3) of Example 3. It is a measurement result of the chromaticity about the mill blank part (4) of Example 4. It is a measurement result of the chromaticity about the mill blank part (5) of Example 5. It is a measurement result of the chromaticity about the mill blank part (6) of the comparative example 1. It is a measurement result of the chromaticity about the mill blank part (7) of the comparative example 2. It is a measurement result of the chromaticity about the mill blank part (8) of the comparative example 3.

The dental mill blank of the present invention has a prismatic mill blank portion having a laminated structure of two or more layers. The mill blank portion has a plurality of side surfaces (P) having at least one curved interface (interface between layers of a laminated structure), and at least two of the side surfaces (P) are not parallel to each other. Typically said curved interface forms a curve on the side surface (P).

[Mill blank part]
An example of an embodiment of a mill blank part according to the present invention is shown in FIG. 1 as a schematic diagram. The rectangular parallelepiped mill blank portion 5 shown in FIG. 1 has a four-layer laminated structure. The mill blank part 5 has interfaces based on the layers of the laminated structure on all of its four side surfaces, and all of these interfaces are curved. Therefore, the mill blank part 5 has four side surfaces (P). In the mill blank portion 5 shown in FIG. 1, adjacent side surfaces (P) are not parallel to each other, and therefore, at least two of the four side surfaces (P) are not parallel to each other.

By having the side surface (P) of the mill blank part 5 having the curved interface 4, it is possible to manufacture a dental prosthesis having an appearance closer to the color tone of natural teeth, and in the resulting dental prosthesis, When force is applied from the direction in which the layers are laminated, the force can be dispersed to the surroundings, improving the compressive strength. In addition, by having a plurality of such side surfaces (P) and at least two of them being not parallel to each other, it is possible to cut out a desired shape for a dental prosthesis from a wide area and process it. The resulting dental prosthesis has a color tone closer to that of natural teeth, and it is possible to easily manufacture a mill blank having such a mill blank portion.

The shape of the curve at the interface of the side surface (P) is not particularly limited, and examples thereof include a circular arc, an elliptical arc, a parabola, a catenary, and a combination of a plurality of these shapes. The shape that is a combination of a plurality of shapes includes, for example, a shape that is a combination of a plurality of different arcuate shapes. Note that the curved interface of the side surface (P) can be formed by mechanical pressure such as pressing. Specifically, it can be easily formed by the method described below.

The mill blank part according to the present invention has a prismatic shape, and examples thereof include a triangular prism shape, a quadrangular prism shape, a pentagonal prism shape, a hexagonal prism shape, and the like. Among these, from the viewpoint of ease of manufacture and handling, a quadrangular prism shape is preferred, and a rectangular parallelepiped shape is more preferred.

As long as the number of side surfaces (P) that the mill blank part according to the present invention has is two or more, there is no particular restriction on the number within the range allowed by the shape of the prismatic mill blank part, but The mill blank part itself can be manufactured more easily. The number of side surfaces (P) is preferably three or more, particularly preferably four or more. It is particularly preferable that the mill blank part has a quadrangular columnar shape (preferably a rectangular parallelepiped shape), and that all four side surfaces thereof are side surfaces (P).

In the mill blank part according to the present invention, it is preferable that the two side surfaces (P) that are not parallel to each other are orthogonal to each other. That is, since the mill blank has at least two side surfaces that are orthogonal to each other, and both of those side surfaces are the side surfaces (P) having curved interfaces, it has an appearance that is closer to the color tone of natural teeth and is machine-friendly. A portion that will become a dental prosthesis with excellent mechanical strength can be cut out from a wider area, and the mill blank itself can be manufactured more easily. It is preferable that the two mutually orthogonal side surfaces (P) are adjacent to each other.

It is preferable that the mill blank part according to the present invention has an imaginary first plane of symmetry that equally divides the laminated structure, and that the first imaginary plane of symmetry has at least one curved interface. In this case, the mill blank further has a virtual second symmetry plane that is perpendicular to the virtual first symmetry plane and equally divides the laminated structure, and the virtual second symmetry plane is Preferably it has at least one curved interface. Here, typically the curved interface forms a curve on the virtual first symmetry plane or the virtual second symmetry plane.

The schematic diagram of FIG. 1 shows a virtual first symmetry plane 2 and a virtual second symmetry plane 3. In FIG. 1, both a virtual first symmetry plane 2 and a virtual second symmetry plane 3 perpendicular thereto have at least one curved interface (not shown). With a mill blank having such a layered mill blank part, it is possible to cut out from a wider area a part that will become a dental prosthesis that has an appearance closer to the color tone of natural teeth and has excellent mechanical strength. In addition, the mill blank itself can be manufactured more easily, and the strength of the mill blank itself and the dental prosthesis obtained from it is improved due to the symmetry. There is no particular restriction on the shape of the curvature at the interface of the virtual first symmetry plane and the virtual second symmetry plane, for example, a circular arc shape, an elliptical arc shape, a parabola shape, a catenary shape, a shape that is a combination of multiple of these shapes. Examples include. The shape that is a combination of a plurality of shapes includes, for example, a shape that is a combination of a plurality of different arcuate shapes.

The number of layers in the laminated structure of the mill blank part according to the present invention is not particularly limited as long as it is two or more layers, but in order to have a more natural gradation and achieve color harmony corresponding to a natural tooth crown. is preferably three or more layers, particularly preferably four or more layers. Further, in the laminated structure, the color tone and/or transparency of each adjacent layer is preferably different from each other. As a scale indicating the color tone, for example, L ^{* ,} a ^* , b ^* in the L*a ^* b ^* color system can be used. As a measure indicating transparency, for example, ΔL ^* in the L ^* a ^* b ^* color system can be used.

In the laminated structure of the mill blank part according to the present invention, it is preferable that all layers contain the inorganic filler (a). With such a configuration, a dental prosthesis with superior mechanical strength can be obtained. Note that the mill blank portion having such a configuration can be manufactured by a method described later.

A preferred embodiment of the mill blank part according to the present invention includes, for example, one composed of a resin block. A mill blank portion composed of a resin block typically contains an inorganic filler (a) and a polymer obtained by polymerizing a polymerizable monomer (b). In yet another embodiment, the mill blank part according to the present invention may be constructed from a ceramic block such as zirconia or glass.

The mill blank part composed of a resin block is formed into a molded article (X) containing the inorganic filler (a) and having a desired layer shape, which is obtained by, for example, press-molding the inorganic filler (a). It can be manufactured by impregnating the composition (Y) containing the polymerizable monomer (b) and then polymerizing and curing it. It is preferable that the composition (Y) further contains a polymerization initiator (c) for polymerizing the polymerizable monomer (b).

In addition, the mill blank part composed of the resin block is prepared by kneading the inorganic filler (a) and the composition (Y) containing the polymerizable monomer (b). After preparing a paste (Z) containing the polymerizable monomer (b), this paste (Z) is press-molded or extruded to form the desired layer shape, and then polymerized. It can also be produced by curing. In this case, a curved mold may be used to form the desired layer shape. The paste (Z) also preferably contains a polymerization initiator (c) for polymerizing the polymerizable monomer (b).

There is no particular restriction on the method for obtaining the molded article (X) having the desired layered shape, but it may contain the inorganic filler (a) alone or be blended with other components such as the pigment (d). Preferably, a method can be employed in which a plurality of powders (powders containing the inorganic filler (a)) are prepared and press-molded using a punch in a mold. By employing such a method, the mill blank part according to the present invention can be obtained more easily.

By appropriately adjusting the type and amount of other components such as pigment (d) for the powders used, the color tone of each powder and, by extension, the color tone of each layer in the resulting mill blank and dental prosthesis can be adjusted. It can be adjusted. Furthermore, by preparing two types of powder and mixing them at different blending ratios, it is also possible to obtain a plurality of powders with different color tones. For example, when manufacturing a mill blank part having a laminated structure of four or more layers, the powder for the two outermost layers is prepared by changing the amounts of other components such as the inorganic filler (a) and the pigment (d). Powder for each intermediate layer can be obtained by preparing and then mixing these two powders while changing the blending ratio.

As a method for forming a curved interface when press-molding using a punch in a mold, for example, after filling the mold with the first powder, a punch with a convex or concave shape is used. A method in which the filling process and the pressing process are alternately repeated, in which the filling process and the pressing process are performed by press-forming using a powder and then filling the second powder; after filling each powder in turn, a punch (preferably a flat punch) is used. Examples include a method of press molding to form a curved interface. In order to achieve a more natural gradation, the latter method, in which the powders are easily mixed together at the interface, is more preferable.

An example of a method of forming a curved interface by press-forming with a punch after sequentially filling each of the powders will be described in detail below. First, a plurality of prepared powders containing the inorganic filler (a) are sequentially filled into a mold to form a laminate. The layer formed from each powder can be planar. Next, this laminate is pressed with a punch to form curved interfaces on the sides of the laminate. At this time, based on the press equipment, punching speed, etc., the pressure from the press is prioritized to be higher in the center of the mold, and the air released due to the press is directed from the center to the periphery. It is possible to form a curved interface. The direction of the curve formed tends to depend on the moving direction of the punch in the press, and in many cases, a curve having a convex shape tends to be formed in the direction in which the punch moves.

Specifically, if the mold frame used is fixed to a support stand and the relative position between the mold frame and the lower punch is not changed and press forming is performed only by relative movement of the upper punch, the curve will be convex downward. The interface between the layers tends to curve into a dome shape from the central vertex toward the periphery. For example, when a two-layer laminate is press-molded only by relative movement of the upper punch, the layered shape is likely to be as shown schematically in FIG. 2A. On the other hand, when press forming is performed by changing the relative positions of the upper punch and the lower punch with respect to the mold frame (preferably changing at the same speed), such as by not fixing the mold frame used to a support, the interface between the layers The upper half of the laminate tends to curve downward in a convex dome shape, and the lower half tends to curve upward in a dome shape. For example, if a three-layer laminate is press-molded by changing the relative positions of the upper punch and lower punch with respect to the mold frame at the same speed, the layered shape is likely to be as shown schematically in Figure 2B. . By selecting the number of layers in the laminate and the punches to be moved, it is possible to create a layer shape as shown in the schematic diagrams in Figures 2C and 2D, or it is possible to create a layered structure in which the curvature of the interfaces is all in the same direction (all convex upward). It may also have a layer shape of a certain four-layer structure (E; having a layer shape as shown in FIG. 1). For the mill blank parts obtained from the molded product (X) having the layer shape (E) of a four-layer structure in which the layer shapes and interface curvatures are all in the same direction (all convex upward) in FIGS. 2A to 2D, hypothetical The cross-sectional views taken when cut along the first symmetry plane 2 are shown as schematic diagrams in FIGS. 3A to 3E, respectively, and the cross-sectional views taken when cut along the virtual second symmetry plane 3 are shown as schematic diagrams shown in FIGS. 4A to 4A, respectively. Shown in Figure 4E.

Even in the case of press molding using the paste (Z), the desired layer shape can be obtained in the same manner as in the case of obtaining the molded body (X). For example, after filling the first paste into the mold, A method in which the filling process and the pressing process are alternately repeated, in which press molding is performed using a punch provided with a convex or concave shape, and then a second paste is filled; after filling each paste in sequence, A method such as press forming with a punch (preferably a flat punch) to form a curved interface can be adopted.

・Inorganic filler (a)
The type of inorganic filler (a) is not particularly limited, and known inorganic particles can be used. Inorganic particles include, for example, various glasses (for example, silicon dioxide (quartz, quartz glass, silica gel, etc.), silicon-based materials containing boron and/or aluminum along with various heavy metals), alumina, and various ceramics. , diatomaceous earth, kaolin, clay minerals (montmorillonite, etc.), activated clay, synthetic zeolite, mica, silica, calcium fluoride, ytterbium fluoride, calcium phosphate, barium sulfate, zirconium dioxide (zirconia), titanium dioxide (titania), hydroxyapatite, etc. can be mentioned. Further, the inorganic filler (a) may be organic-inorganic composite particles (organic-inorganic composite filler) obtained by adding a polymerizable monomer to the inorganic particles, polymerizing and curing the particles, and then crushing the particles. In addition, the inorganic filler (a) may be used alone or in combination of two or more.

The shape of the inorganic particles used as the inorganic filler (a) is not particularly limited, and is, for example, crushed, plate-like, scale-like, fibrous (short fiber, long fiber), needle-like, whisker, or spherical. The inorganic particles may be an agglomeration of primary particles having the above-mentioned shapes, or may be a mixture of a plurality of primary particles having different shapes. Moreover, the inorganic particles may be subjected to some kind of treatment (for example, pulverization, etc.) so as to have the above shape.

・Pigment (d)
By including the pigment (d) in at least one of the molded body (X), the composition (Y), and the paste (Z), a desired type and/or amount of pigment is added to each layer constituting the mill blank part. By including (d), the chromaticity, tone, transparency, etc. of each of these layers can be adjusted. In the case where a mill blank part is produced by impregnating the molded body (X) with the composition (Y) and then polymerizing and curing it, the pigment (d) is preferably included in the molded body (X).

As the pigment (d), known pigments used in dental compositions can be used. The pigment (d) may be either an inorganic pigment or an organic pigment.

Inorganic pigments include, for example, chromates such as yellow lead, zinc yellow, and barium yellow; ferrocyanides such as navy blue; sulfides such as silver vermilion, cadmium yellow, zinc sulfide, antimony white, and cadmium red; barium sulfate and sulfuric acid. Sulfates such as zinc and strontium sulfate; oxides such as zinc white, titanium oxide, red iron oxide (red iron oxide), black iron oxide, yellow iron oxide, and chromium oxide; hydroxides such as aluminum hydroxide; calcium silicate, Examples include silicates such as ultramarine; carbon such as carbon black and graphite.

Examples of organic pigments include nitroso pigments such as Naphthol Green B and Naphthol Green Y; nitro pigments such as Naphthol S and Lysol Fast Yellow 2G; and insoluble azo pigments such as Permanent Red 4R, Brilliant Fast Scarlet, Hansa Yellow, and Benzidine Yellow. Pigments; poorly soluble azo pigments such as Lysol Red, Lake Red C, and Lake Red D; soluble azo pigments such as Brilliant Carmine 6B, Permanent Red F5R, Pigment Scarlet 3B, and Bordeaux 10B; Phthalocyanine Blue, Phthalocyanine Green, and Sky Blue Basic dye pigments such as rhodamine lake, malachite green lake, and methyl violet lake; Acid dye pigments such as peacock blue lake, eosin lake, and quinoline yellow lake.

These pigments (d) may be used alone or in combination of two or more. Among these pigments (d), inorganic pigments are preferred because they have excellent heat resistance, light resistance, etc., and titanium oxide, red iron oxide, iron oxide black, and iron oxide yellow are more preferred.

The amount of pigment (d) to be used can be adjusted as appropriate depending on the desired chromaticity, tone, transparency, etc. of each layer, and is not particularly limited, but the amount of pigment (d) in the final mill blank part In the blended layer, the content of pigment (d) is preferably 0.000001 to 5 parts by mass, more preferably 0.00001 to 1 part by mass, relative to 100 parts by mass of inorganic filler (a). It is best to use it for

When the molded article (X) contains the pigment (d), it is preferable that the inorganic filler (a) and the pigment (d) contained in the molded article (X) are uniformly dispersed. There is no particular restriction on the mixing method for uniformly dispersing the inorganic filler (a) and pigment (d) in the molded body (X), and a known mixing method for mixing and dispersing powder may be appropriately adopted. be able to. The mixing method may be either a dry method or a wet method, but inorganic filler (a) and pigment (d) can be mixed and dispersed more uniformly in the presence of a solvent. A preferred method is to disperse the filler (a) and the pigment (d) and then remove the solvent by distilling off or the like. The dispersion can be carried out by appropriately adopting a known method, and for example, a dispersing machine such as a sand mill, bead mill, attritor, colloid mill, ball mill, ultrasonic crusher, homomixer, dissolver, or homogenizer can be used. . Preferred dispersion conditions vary depending on the particle size and usage amount of the inorganic filler (a) and the pigment (d); the type and usage amount of the solvent; the type of dispersion machine, etc. Dispersion conditions such as dispersion time, stirring tool, rotation speed, etc. may be appropriately selected depending on the dispersion situation. The solvent is preferably water and/or a solvent compatible with water. Examples of the solvent include organic solvents such as alcohols (e.g., ethanol, methanol, isopropanol, etc.), ethers, ketones (e.g., acetone, methyl ethyl ketone, etc.), and inorganic acids (e.g., hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, etc.). etc.) and other inorganic solvents.

・Polymerizable monomer (b)
As the polymerizable monomer (b), known polymerizable monomers used in dental composite resins and the like can be used, and in general, radically polymerizable monomers are preferably used. Specific examples of radically polymerizable monomers include carboxylic acids such as α-cyanoacrylic acid, (meth)acrylic acid, α-halogenated acrylic acid, crotonic acid, cinnamic acid, sorbic acid, maleic acid, and itaconic acid. Examples include acid esters; (meth)acrylamide; (meth)acrylamide derivatives; vinyl esters; vinyl ethers; mono-N-vinyl derivatives; styrene derivatives. Among these, carboxylic acid esters and (meth)acrylamide derivatives are preferred, (meth)acrylic esters and (meth)acrylamide derivatives are more preferred, and (meth)acrylic esters are even more preferred. In this specification, the expression "(meth)acrylic" is used to include both methacrylic and acrylic. Examples of (meth)acrylic acid esters and (meth)acrylamide derivatives are shown below.

(i) Monofunctional (meth)acrylic esters and (meth)acrylamide derivatives, such as methyl (meth)acrylate, isobutyl (meth)acrylate, benzyl (meth)acrylate, lauryl (meth)acrylate, 2-(N, N-dimethylamino)ethyl (meth)acrylate, 2,3-dibromopropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, propylene Glycol mono(meth)acrylate, glycerin mono(meth)acrylate, erythritol mono(meth)acrylate, N-methylol(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, N-dihydroxyethyl(meth)acrylamide, (meth) Examples include acryloyloxydodecylpyridinium bromide, (meth)acryloyloxydodecylpyridinium chloride, (meth)acryloyloxyhexadecylpyridinium chloride, (meth)acryloyloxydecyl ammonium chloride, and 10-mercaptodecyl (meth)acrylate.

(ii) Difunctional (meth)acrylic acid ester For example, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1 , 6-hexanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 2,2-bis[4-(3-acryloyloxy-2-hydroxypropoxy)phenyl]propane, 2,2- Bis[4-[3-methacryloyloxy-2-hydroxypropoxy]phenyl]propane (commonly known as Bis-GMA), 2,2-bis[4-(meth)acryloyloxyethoxyphenyl]propane, 2,2-bis[4 -(meth)acryloyloxypolyethoxyphenyl]propane, 1,2-bis[3-(meth)acryloyloxy2-hydroxypropoxy]ethane, pentaerythritol di(meth)acrylate, [2,2,4-trimethylhexamethylene Bis(2-carbamoyloxyethyl)] dimethacrylate (commonly known as UDMA), 2,2,3,3,4,4-hexafluoro-1,5-pentyl di(meth)acrylate, and the like.

(iii) Trifunctional or higher functional (meth)acrylic acid ester For example, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate , dipentaerythritol hexa(meth)acrylate, N,N'-(2,2,4-trimethylhexamethylene)bis[2-(aminocarboxy)propane-1,3-diol]tetra(meth)acrylate, 1, Examples include 7-diacryloyloxy-2,2,6,6-tetra(meth)acryloyloxymethyl-4-oxyheptane.

In addition, as the polymerizable monomer (b), in addition to the above-mentioned radically polymerizable monomers, cationically polymerizable monomers such as oxirane compounds and oxetane compounds can also be used.

The polymerizable monomer (b) may be used alone or in combination of two or more. Further, although it is preferable that the polymerizable monomer (b) is in a liquid state, it is not necessarily required to be in a liquid state at room temperature. It can be used by mixing and dissolving it with a monomer.

The viscosity (25° C.) of the polymerizable monomer (b) is preferably 10 Pa·s or less, more preferably 5 Pa·s or less, and even more preferably 2 Pa·s or less. On the other hand, when using a mixture of two or more polymerizable monomers (b) or diluting them in a solvent, the viscosity of each individual polymerizable monomer (b) must be within the above range. It is preferable that the viscosity is within the above range in the state of use (mixed/diluted state).

・Polymerization initiator (c)
As the polymerization initiator (c), polymerization initiators used in general industry can be used, and in particular, polymerization initiators used in dental applications can be preferably used. As the polymerization initiator (c), for example, at least one selected from the group consisting of a thermal polymerization initiator (c-1), a photopolymerization initiator (c-2), and a chemical polymerization initiator (c-3). Can be used.

(Heating polymerization initiator (c-1))
Examples of the thermal polymerization initiator (c-1) include organic peroxides and azo compounds.

Examples of the organic peroxides include ketone peroxides, hydroperoxides, diacyl peroxides, dialkyl peroxides, peroxyketals, peroxyesters, peroxydicarbonates, and the like.

Examples of the ketone peroxide include methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, methyl cyclohexanone peroxide, and cyclohexanone peroxide.

Examples of the hydroperoxide include 2,5-dimethylhexane-2,5-dihydroperoxide, diisopropylbenzene hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, etc. can be mentioned.

Examples of the diacyl peroxide include acetyl peroxide, isobutyryl peroxide, benzoyl peroxide, decanoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, 2,4-dichlorobenzoyl peroxide, and lauroyl peroxide.

Examples of the dialkyl peroxide include di-t-butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and 1,3-bis( Examples include t-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne, and the like.

Examples of peroxyketals include 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, and 2,2-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane. (peroxy)butane, 2,2-bis(t-butylperoxy)octane, 4,4-bis(t-butylperoxy)valeric acid n-butyl ester, and the like.

Examples of peroxyesters include α-cumylperoxyneodecanoate, t-butylperoxyneodecanoate, t-butylperoxypivalate, 2,2,4-trimethylpentylperoxy-2-ethylhexanoate, t-Amylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, di-t-butylperoxyisophthalate, di-t-butylperoxyhexahydroterephthalate, t-butylperoxy-3, Examples include 3,5-trimethylhexanoate, t-butylperoxyacetate, t-butylperoxybenzoate, and t-butylperoxymaleate.

Examples of peroxydicarbonates include di-3-methoxyperoxydicarbonate, di-2-ethylhexylperoxydicarbonate, bis(4-t-butylcyclohexyl)peroxydicarbonate, diisopropylperoxydicarbonate, di-n-propylperoxy Examples include dicarbonate, di-2-ethoxyethyl peroxydicarbonate, diallyl peroxydicarbonate, and the like.

Among these organic peroxides, diacyl peroxide is preferably used from the viewpoint of a comprehensive balance of safety, storage stability, and radical generation ability, and among these, benzoyl peroxide is more preferably used.

Examples of azo compounds include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 4,4'-azobis(4-cyanovaleric acid), Examples include 1,1'-azobis(1-cyclohexanecarbonitrile), dimethyl-2,2'-azobis(isobutyrate), and 2,2'-azobis(2-aminopropane) dihydrochloride.

(Photopolymerization initiator (c-2))
As the photopolymerization initiator (c-2), those widely used in dental curable compositions can be preferably used, such as (bis)acylphosphine oxides, α-diketones, and coumarins. Examples include.

Among the (bis)acylphosphine oxides, examples of the acylphosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,6-dimethoxybenzoyldiphenylphosphine oxide, and 2,6-dichlorobenzoyldiphenylphosphine. oxide, 2,4,6-trimethylbenzoylmethoxyphenylphosphine oxide, 2,4,6-trimethylbenzoylethoxyphenylphosphine oxide, 2,3,5,6-tetramethylbenzoyldiphenylphosphine oxide, benzoyl di-(2,6- dimethylphenyl)phosphonate, salts thereof, and the like.

Among the (bis)acylphosphine oxides, examples of bisacylphosphine oxides include bis(2,6-dichlorobenzoyl)phenylphosphine oxide, bis(2,6-dichlorobenzoyl)-2,5-dimethylphenyl Phosphine oxide, bis(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis(2,6-dimethoxybenzoyl)phenylphosphine oxide, bis (2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl) Examples include phenylphosphine oxide, bis(2,3,6-trimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide, and salts thereof.

Among these (bis)acylphosphine oxides, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylmethoxyphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine The sodium salt of the oxide, 2,4,6-trimethylbenzoylphenylphosphine oxide, is preferred.

Examples of α-diketones include diacetyl, benzyl, camphorquinone, 2,3-pentadione, 2,3-octadione, 9,10-phenanthrenequinone, 4,4'-oxybenzyl, acenaphthenequinone, etc. . Among these, camphorquinone is preferred.

Examples of coumarins include 3,3'-carbonylbis(7-diethylaminocoumarin), 3-(4-methoxybenzoyl)coumarin, 3-thienylcoumarin, 3-benzoyl-5,7-dimethoxycoumarin, and 3-benzoylcoumarin. -7-methoxycoumarin, 3-benzoyl-6-methoxycoumarin, 3-benzoyl-8-methoxycoumarin, 3-benzoylcoumarin, 7-methoxy-3-(p-nitrobenzoyl)coumarin, 3-(p-nitrobenzoyl) ) Coumarin, 3,5-carbonylbis(7-methoxycoumarin), 3-benzoyl-6-bromocoumarin, 3,3'-carbonylbiscoumarin, 3-benzoyl-7-dimethylaminocoumarin, 3-benzoylbenzo[f ] Coumarin, 3-carboxycoumarin, 3-carboxy-7-methoxycoumarin, 3-ethoxycarbonyl-6-methoxycoumarin, 3-ethoxycarbonyl-8-methoxycoumarin, 3-acetylbenzo[f]coumarin, 3-benzoyl- 6-Nitrocoumarin, 3-benzoyl-7-diethylaminocoumarin, 7-dimethylamino-3-(4-methoxybenzoyl)coumarin, 7-diethylamino-3-(4-methoxybenzoyl)coumarin, 7-diethylamino-3-( 4-diethylamino)coumarin, 7-methoxy-3-(4-methoxybenzoyl)coumarin, 3-(4-nitrobenzoyl)benzo[f]coumarin, 3-(4-ethoxycinnamoyl)-7-methoxycoumarin, 3 -(4-dimethylaminocinnamoyl)coumarin, 3-(4-diphenylaminocinnamoyl)coumarin, 3-[(3-dimethylbenzothiazol-2-ylidene)acetyl]coumarin, 3-[(1-methylnaphtho[1 ,2-d]thiazol-2-ylidene)acetyl]coumarin, 3,3'-carbonylbis(6-methoxycoumarin), 3,3'-carbonylbis(7-acetoxycoumarin), 3,3'-carbonylbis (7-dimethylaminocoumarin), 3-(2-benzothiazoyl)-7-(diethylamino)coumarin, 3-(2-benzothiazoyl)-7-(dibutylamino)coumarin, 3-(2-benzimidazo yl)-7-(diethylamino)coumarin, 3-(2-benzothiazoyl)-7-(dioctylamino)coumarin, 3-acetyl-7-(dimethylamino)coumarin, 3,3'-carbonylbis(7- dibutylaminocoumarin), 3,3'-carbonyl-7-diethylaminocoumarin-7'-bis(butoxyethyl)aminocoumarin, 10-[3-[4-(dimethylamino)phenyl]-1-oxo-2-propenyl ]-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H,11H-[1]benzopyrano[6,7,8-ij]quinolidin-11one, 10-( 2-benzothiazoyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H,11H-[1]benzopyrano[6,7,8-ij]quinolidine-11 - On, etc.

Among these coumarin compounds, 3,3'-carbonylbis(7-diethylaminocoumarin) and 3,3'-carbonylbis(7-dibutylaminocoumarin) are preferred.

(Chemical polymerization initiator (c-3))
Examples of the chemical polymerization initiator include redox polymerization initiators. As the redox polymerization initiator, organic peroxide-amine type, organic peroxide-amine-sulfinic acid (or salt thereof) type, etc. can be preferably used. When using a redox polymerization initiator, it is preferable to package the oxidizing agent and reducing agent separately and mix them immediately before use.

Examples of the oxidizing agent for the redox polymerization initiator include organic peroxides. As the organic peroxides, known ones can be used, and specifically, the organic peroxides exemplified in the thermal polymerization initiator (c-1) can be used. As the organic peroxides, diacyl peroxide is preferably used from the viewpoint of overall balance of safety, storage stability, and radical generation ability, and among these, benzoyl peroxide is more preferably used.

As a reducing agent for a redox polymerization initiator, a tertiary aromatic amine that does not have an electron-withdrawing group in its aromatic ring is usually used. Examples of tertiary aromatic amines having no electron-withdrawing group on the aromatic ring include N,N-dimethylaniline, N,N-dimethyl-p-toluidine, N,N-dimethyl-m-toluidine, N, N-diethyl-p-toluidine, N,N-dimethyl-3,5-dimethylaniline, N,N-dimethyl-3,4-dimethylaniline, N,N-dimethyl-4-ethylaniline, N,N-dimethyl -4-isopropylaniline, N,N-dimethyl-4-t-butylaniline, N,N-dimethyl-3,5-di-t-butylaniline, N,N-bis(2-hydroxyethyl)-3, 5-dimethylaniline, N,N-bis(2-hydroxyethyl)-p-toluidine, N,N-bis(2-hydroxyethyl)-3,4-dimethylaniline, N,N-bis(2-hydroxyethyl) )-4-ethylaniline, N,N-bis(2-hydroxyethyl)-4-isopropylaniline, N,N-bis(2-hydroxyethyl)-4-t-butylaniline, N,N-bis(2-hydroxyethyl)-4-t-butylaniline, N,N-bis(2-hydroxyethyl)-4-t-butylaniline, -hydroxyethyl)-3,5-diisopropylaniline, N,N-bis(2-hydroxyethyl)-3,5-di-t-butylaniline, and the like.

The polymerization initiator (c) may be used alone or in combination of two or more. In particular, as the polymerization initiator (c), it is preferable to use a thermal polymerization initiator (c-1) and a photopolymerization initiator (c-2) in combination, and to use diacyl peroxide and (bis)acylphosphine oxides in combination. It is more preferable.

The amount of the polymerization initiator (c) used is not particularly limited, but from the viewpoint of curability etc., it is preferably 0.001 parts by mass or more with respect to 100 parts by mass of the polymerizable monomer (b), and 0. It is more preferably .05 parts by mass or more, and even more preferably 0.1 parts by mass or more. By using the amount of the polymerization initiator (c) equal to or higher than the above lower limit value, even if the polymerization performance of the polymerization initiator itself is low, the mill blank obtained by sufficiently proceeding with polymerization and the mill blank obtained therefrom. The strength of the dental prosthesis is improved. On the other hand, the amount of the polymerization initiator (c) used is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, based on 100 parts by mass of the polymerizable monomer (b). When the amount of the polymerization initiator (c) used is at most the above upper limit, precipitation of the polymerization initiator (c) can be suppressed.

・Polymerization accelerator (e)
When using the polymerization initiator (c), a polymerization accelerator (e) may be used in combination. As the polymerization accelerator (e), polymerization accelerators used in general industry can be used, and in particular, polymerization accelerators used in dental applications can be preferably used. The polymerization accelerator (e) may be used alone or in combination of two or more.

Examples of the polymerization accelerator (e) suitable for the photopolymerization initiator (c-2) include tertiary amines, aldehydes, thiols, sulfinic acids and salts thereof. By using a polymerization accelerator (e) together with the photopolymerization initiator (c-2), photopolymerization can be carried out more efficiently in a shorter time.

Examples of the tertiary amine used as the polymerization accelerator (e) of the photopolymerization initiator (c-2) include N,N-dimethylaniline, N,N-dimethyl-p-toluidine, and N,N-dimethyl. -m-Toluidine, N,N-diethyl-p-toluidine, N,N-dimethyl-3,5-dimethylaniline, N,N-dimethyl-3,4-dimethylaniline, N,N-dimethyl-4-ethyl Aniline, N,N-dimethyl-4-isopropylaniline, N,N-dimethyl-4-t-butylaniline, N,N-dimethyl-3,5-di-t-butylaniline, N,N-bis(2 -hydroxyethyl)-3,5-dimethylaniline, N,N-bis(2-hydroxyethyl)-p-toluidine, N,N-bis(2-hydroxyethyl)-3,4-dimethylaniline, N,N -bis(2-hydroxyethyl)-4-ethylaniline, N,N-bis(2-hydroxyethyl)-4-isopropylaniline, N,N-bis(2-hydroxyethyl)-4-t-butylaniline, N,N-bis(2-hydroxyethyl)-3,5-diisopropylaniline, N,N-bis(2-hydroxyethyl)-3,5-di-t-butylaniline, 4-(N,N-dimethyl n-butoxyethyl amino)benzoate, (2-methacryloyloxy)ethyl 4-(N,N-dimethylamino)benzoate, ethyl 4-(N,N-dimethylamino)benzoate, 4-(N,N- butyl dimethylamino)benzoate, N-methyldiethanolamine, 4-(N,N-dimethylamino)benzophenone, trimethylamine, triethylamine, N-methyldiethanolamine, N-ethyldiethanolamine, Nn-butyldiethanolamine, N-lauryldiethanolamine, Examples include triethanolamine, 2-(dimethylamino)ethyl methacrylate, N-methyldiethanolamine dimethacrylate, N-ethyldiethanolamine dimethacrylate, triethanolamine monomethacrylate, triethanolamine dimethacrylate, and triethanolamine trimethacrylate.

Examples of aldehydes used as the polymerization accelerator (e) for the photopolymerization initiator (c-2) include dimethylaminobenzaldehyde and terephthalaldehyde.

Examples of the thiol group compound used as the polymerization accelerator (e) of the photopolymerization initiator (c-2) include 2-mercaptobenzoxazole, decanethiol, 3-mercaptopropyltrimethoxysilane, and thiobenzoic acid. It will be done.

Examples of the sulfinic acid and its salt used as the polymerization accelerator (e) of the photopolymerization initiator (c-2) include benzenesulfinic acid, sodium benzenesulfinate, potassium benzenesulfinate, calcium benzenesulfinate, and benzenesulfin. Lithium acid, p-toluenesulfinic acid, sodium p-toluenesulfinate, potassium p-toluenesulfinate, calcium p-toluenesulfinate, lithium p-toluenesulfinate, 2,4,6-trimethylbenzenesulfinic acid, 2, Sodium 4,6-trimethylbenzenesulfinate, potassium 2,4,6-trimethylbenzenesulfinate, calcium 2,4,6-trimethylbenzenesulfinate, lithium 2,4,6-trimethylbenzenesulfinate, 2,4, 6-triethylbenzenesulfinic acid, sodium 2,4,6-triethylbenzenesulfinate, potassium 2,4,6-triethylbenzenesulfinate, calcium 2,4,6-triethylbenzenesulfinate, 2,4,6-triethylbenzenesulfinate Examples include isopropylbenzenesulfinic acid, sodium 2,4,6-triisopropylbenzenesulfinate, potassium 2,4,6-triisopropylbenzenesulfinate, and calcium 2,4,6-triisopropylbenzenesulfinate.

Examples of the polymerization accelerator (e) suitable for the chemical polymerization initiator (c-3) include amines, sulfinic acids and salts thereof, copper compounds, and tin compounds.

The amines used as the polymerization promoter (e) of the chemical polymerization initiator (c-3) are classified into aliphatic amines and aromatic amines having an electron-withdrawing group in the aromatic ring.
Examples of the aliphatic amines include primary aliphatic amines such as n-butylamine, n-hexylamine, and n-octylamine; secondary aliphatic amines such as diisopropylamine, dibutylamine, and N-methylethanolamine; ; N-methyldiethanolamine, N-ethyldiethanolamine, Nn-butyldiethanolamine, N-lauryldiethanolamine, 2-(dimethylamino)ethyl methacrylate, N-methyldiethanolamine dimethacrylate, N-ethyldiethanolamine dimethacrylate, triethanolamine mono Examples include tertiary aliphatic amines such as methacrylate, triethanolamine dimethacrylate, triethanolamine trimethacrylate, triethanolamine, trimethylamine, triethylamine, and tributylamine. Among these, from the viewpoint of curability and storage stability, tertiary aliphatic amines are preferred, and N-methyldiethanolamine and triethanolamine are more preferred.

Examples of the aromatic amine having an electron-withdrawing group on the aromatic ring include N,N-bis(2-hydroxyethyl)-p-toluidine, 4-(N,N-dimethylamino)ethyl benzoate, 4- Methyl (N,N-dimethylamino)benzoate, n-butoxyethyl 4-(N,N-dimethylamino)benzoate, 2-(methacryloyloxy)ethyl 4-(N,N-dimethylamino)benzoate, 4 Examples include tertiary aromatic amines such as -(N,N-dimethylamino)benzophenone and butyl 4-(N,N-dimethylamino)benzoate. Among these, N,N-bis(2-hydroxyethyl)-p-toluidine, ethyl 4-(N,N-dimethylamino)benzoate, 4-(N,N At least one selected from the group consisting of n-butoxyethyl -dimethylamino)benzoate and 4-(N,N-dimethylamino)benzophenone is preferred.

Examples of sulfinic acids and salts thereof used as the polymerization accelerator (e) for the chemical polymerization initiator (c-3) include those exemplified as the polymerization accelerator (e) for the photopolymerization initiator (c-2) described above. Among them, sodium benzenesulfinate, sodium p-toluenesulfinate, and sodium 2,4,6-triisopropylbenzenesulfinate are preferred.

Examples of the copper compound used as the polymerization accelerator (e) of the chemical polymerization initiator (c-3) include copper acetylacetone, cupric acetate, copper oleate, cupric chloride, cupric bromide, etc. Can be mentioned.

Examples of the tin compound used as the polymerization accelerator (e) of the chemical polymerization initiator (c-3) include di-n-butyltin dimaleate, di-n-octyltin dimaleate, di-n-octyltin dilaurate, Examples include di-n-butyltin dilaurate. Particularly preferred tin compounds are di-n-octyltin dilaurate and di-n-butyltin dilaurate.

There is no particular restriction on the method of impregnating the molded article (X) having the desired layer shape with the composition (Y), and it can be carried out by bringing the two into contact. Although the impregnation may be performed under normal pressure, impregnation can be performed more effectively by performing it under reduced pressure. After impregnating, it can be dried using a hot air dryer, if necessary.

After impregnating the molded body (X) with the composition (Y) as described above, the mill blank part according to the present invention can be formed by polymerizing and curing the molded body (X). Also, when forming a mill blank part using paste (Z), the mill blank part according to the present invention can be formed by polymerizing and curing after forming the desired layer shape.

There is no particular restriction on the method of polymerization curing, and polymerization methods such as thermal polymerization, photopolymerization, chemical polymerization, etc. can be appropriately employed depending on the type of polymerization initiator (c) used. In the case of heating polymerization, there is no particular restriction on the heating temperature, and it can be set within the range of 40 to 150°C, for example. Further, the heating time is not particularly limited, and can be set within the range of 1 to 70 hours, for example. On the other hand, in the case of photopolymerization, the light used is not particularly limited, and may be visible light, ultraviolet light, or other light. There is no particular restriction on the photopolymerization time either, and it can be, for example, within a range of 1 to 20 minutes.

[Mill blank]
It is preferable that the mill blank of the present invention has the mill blank part, and has the mill blank part and a support part. The support allows the mill blank to be fixed to the milling device. There is no particular restriction on the method of attaching the support part to the mill blank part, and for example, the mill blank part and the support part can be bonded together using an adhesive or the like.

The mill blank of the present invention is used for dental applications, such as inlays, onlays, veneers, crowns, bridges, abutment teeth, dental posts, dentures, denture bases, and implants by cutting with a dental CAD/CAM system. It can be suitably used for producing dental prostheses such as members (fixtures, abutments), etc. There are no particular limitations on the method for producing a dental prosthesis from the mill blank of the present invention, and any known method can be employed as appropriate.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to examples, but the present invention is not limited to the following examples.

[Production Example 1] Preparation of composition (Y) 70 parts by mass of [2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)]dimethacrylate (UDMA) as the polymerizable monomer (b) and A composition (Y) containing the polymerizable monomer (b) is prepared by dissolving 1 part by mass of benzoyl peroxide, which is a thermal polymerization initiator (c-1), in 30 parts by mass of triethylene glycol dimethacrylate (TEGDMA). was prepared.

[Production Example 2] Preparation of powder containing inorganic filler (a) Commercially available inorganic ultrafine particles (manufactured by Nippon Aerosil Co., Ltd., Aerosil (registered trademark) OX 50, average primary particle diameter 40 nm, BET specific surface area 50 m ² /g ) was dispersed in 500 mL of water, 7 g of γ-methacryloxypropyltrimethoxysilane and a trace amount of pigment were added thereto, and the mixture was stirred at room temperature for 2 hours. As pigments, Japanese titanium oxide, iron oxide black, iron oxide red (red iron oxide), and iron oxide yellow were used. This was spray-dried using a spray dryer (Mini Spray Dryer B290 manufactured by Nippon Buchi Co., Ltd.) and then dried at 90°C for 3 hours to obtain a powder containing the surface-treated inorganic filler (a). . Powder (1) corresponding to the enamel layer and powder (2) corresponding to the dentin layer were obtained by varying the minute amount of the pigment. The obtained two powders (1) and powder (2) are powder (1):powder (2) (mass ratio) of 60:40, 20:80, and 50:50, respectively. The mixture was dry mixed to obtain powder (3), powder (4), and powder (5) for the intermediate layer, respectively.

[Example 1] Production of a mill blank part (vertically curved) having a 4-layer laminated structure 1.09 g each of powder (1), powder (3), powder (4), and powder (2) The mixture was sequentially filled in this order onto the lower punch rod of a rectangular press mold of 14.7 mm x 18.2 mm to form a laminate. At this stage, each layer was made into a planar shape. Each powder was leveled by tapping. Next, set the upper punch rod at a predetermined position, and operate the press machine so that the relative positions of the upper punch and lower punch with respect to the mold frame change at the same speed without fixing the mold frame to the support stand. A uniaxial press (press pressure: 60 MPa, time: 1 minute) was performed using the same. Thereafter, the upper punch and the lower punch were removed from the mold, and a molded product (X-1) having a four-layered shape was taken out.
Thereafter, the molded body (X-1) was placed inside a polyethylene bag, and the composition (Y) containing the polymerizable monomer (b) obtained in Production Example 1 was placed inside the bag. The molded article (X-1) was impregnated with the composition (Y) by introducing the composition and reducing the pressure inside the bag. This was left standing at room temperature under reduced pressure for 1 day, and then heated at 55° C. for 18 hours using a hot air dryer.
Thereafter, this was heat-treated at 110° C. for 3 hours to polymerize and harden the polymerizable monomer (b), thereby obtaining the desired mill blank part (1). This mill blank part (1) had a rectangular parallelepiped shape and had a four-layer laminated structure, and its size was 14.9 mm x 18.4 mm x 15.5 mm. Moreover, this mill blank part (1) has a virtual first symmetry plane and a virtual second symmetry plane perpendicular to this, and in both of these planes, curved interfaces as shown in FIGS. 3C and 4C are formed. It had

[Example 2] Manufacture of a mill blank part (unidirectionally curved) having a four-layer laminated structure In Example 1, the mold frame was fixed to the support stand and the relative position between the mold frame and the lower punch was not changed. A molded product (X-2) having a four-layer shape was obtained in the same manner as in Example 1, except that uniaxial pressing was performed only by relative movement of the upper punch. Using this molded body (X-2), the desired mill blank part (2) was obtained in the same manner as in Example 1. This mill blank part (2) had a rectangular parallelepiped shape and had a four-layer laminated structure, and its size was 14.9 mm x 18.4 mm x 15.5 mm. Moreover, this mill blank part (2) has a virtual first symmetry plane and a virtual second symmetry plane perpendicular to this, and in both of these planes, curved interfaces as shown in FIGS. 3E and 4E are formed. It had

[Example 3] Production of a mill blank part (vertically curved) having a three-layer laminated structure Powder (1), powder (5), and powder (2) were each 1.45 g each, 14.7 mm× The mixture was sequentially filled in this order onto the lower punch bar of a 18.2 mm rectangular press mold to form a laminate. At this stage, each layer was made into a planar shape. Each powder was leveled by tapping. Next, set the upper punch rod at a predetermined position, and operate the press machine so that the relative positions of the upper punch and lower punch with respect to the mold frame change at the same speed without fixing the mold frame to the support stand. A uniaxial press (press pressure: 60 MPa, time: 1 minute) was performed using the same. Thereafter, the upper punch and the lower punch were removed from the mold, and a molded article (X-3) having a three-layer shape was taken out.
Using the obtained molded body (X-3), the desired mill blank part (3) was obtained in the same manner as in Example 1. This mill blank part (3) had a rectangular parallelepiped shape and a three-layer laminated structure, and its size was 14.9 mm x 18.4 mm x 15.5 mm. Moreover, this mill blank part (3) has a virtual first symmetry plane and a virtual second symmetry plane perpendicular to this, and in both of these planes, curved interfaces as shown in FIGS. 3B and 4B are formed. It had

[Example 4] Manufacturing a mill blank part (unidirectionally curved) having a three-layer laminated structure In Example 3, the mold frame was fixed to the support stand and the relative position between the mold frame and the lower punch was not changed. A molded product (X-4) having a three-layer shape was obtained in the same manner as in Example 3, except that uniaxial pressing was performed using only relative movement of the upper punch. Using this molded body (X-4), the desired mill blank part (4) was obtained in the same manner as in Example 1. This mill blank part (4) had a rectangular parallelepiped shape and a three-layer laminated structure, and its size was 14.9 mm x 18.4 mm x 15.5 mm. Moreover, this mill blank part (4) has a virtual first symmetry plane and a virtual second symmetry plane perpendicular to this, and in both of these planes, curved interfaces as shown in FIGS. 3D and 4D are formed. It had

[Example 5] Production of a mill blank part (unidirectionally curved) having a two-layer laminated structure Powder (1) and powder (2) were each 2.18 g each in a rectangular shape of 14.7 mm x 18.2 mm. They were sequentially filled in this order onto the lower punch rod of the press mold to form a laminate. At this stage, each layer was made into a planar shape. Each powder was leveled by tapping. Next, the upper punch rod was installed in a predetermined position, and the mold frame was fixed to the support base. In this state, using a press machine, uniaxial pressing was performed (press pressure: 60 MPa, time: 1 minute) by only relative movement of the upper punch without changing the relative position of the mold frame and the lower punch. Thereafter, the upper punch and the lower punch were removed from the mold, and a molded product (X-5) having a two-layer shape was taken out.
Using the obtained molded body (X-5), a desired mill blank part (5) was obtained in the same manner as in Example 1. This mill blank part (5) had a rectangular parallelepiped shape and a two-layer laminated structure, and its size was 14.9 mm x 18.4 mm x 15.5 mm. Moreover, this mill blank part (5) has a virtual first symmetry plane and a virtual second symmetry plane perpendicular to this, and in both of these planes, curved interfaces as shown in FIGS. 3A and 4A are formed. It had

[Comparative Example 1] Production of a mill blank having a 4-layer laminated structure 1.09 g of powder (1) was filled onto the lower punch rod of a 14.7 mm x 18.2 mm rectangular press mold. , the powder was leveled by tapping. Next, the upper punch rod was installed at a predetermined position, and uniaxial pressing was performed using a press machine (press pressure: 15 MPa). After that, the upper punch rod was removed, and 1.09 g of powder (3) was filled on top of the powder (1) that had been uniaxially pressed. Next, the upper punch rod was placed in a predetermined position, and the A uniaxial press (press pressure: 15 MPa) was performed using a machine. Thereafter, the upper punch rod was removed, and 1.09 g of powder (4) was filled onto the powder (3) that had been uniaxially pressed in the same manner. Next, the upper punch rod was placed in a predetermined position. A uniaxial press (press pressure: 15 MPa) was performed using a press machine. Thereafter, the upper punch rod was removed, and 1.09 g of powder (2) was filled onto the powder (4), which had been uniaxially pressed in the same manner, and then the upper punch rod was placed in a predetermined position. A uniaxial press (press pressure: 60 MPa, time: 1 minute) was performed using a press machine. Thereafter, the upper punch and the lower punch were removed from the mold, and a molded product (X-6) having a four-layer shape was taken out.
Using the obtained molded body (X-6), a desired mill blank part (6) was obtained in the same manner as in Example 1. This mill blank part (6) had a rectangular parallelepiped shape and had a four-layer laminated structure, and its size was 14.9 mm x 18.4 mm x 15.5 mm.

[Comparative Example 2] Production of a mill blank having a three-layer laminated structure 1.45 g of powder (1) was filled onto the lower punch rod of a 14.7 x 18.2 mm rectangular press die. , the powder was leveled by tapping. Next, the upper punch rod was installed at a predetermined position, and uniaxial pressing was performed using a press machine (press pressure: 15 MPa). After that, the upper punch rod was removed, and 1.45 g of powder (5) was filled on top of the powder (1) that had been uniaxially pressed. Next, the upper punch rod was placed in a predetermined position, and the A uniaxial press (press pressure: 15 MPa) was performed using a machine. Thereafter, the upper punch rod was removed, and 1.45 g of powder (2) was filled onto the powder (5) that had been uniaxially pressed in the same manner. Next, the upper punch rod was placed in a predetermined position. A uniaxial press (press pressure: 60 MPa, time: 1 minute) was performed using a press machine. Thereafter, the upper punch and the lower punch were removed from the mold, and a molded article (X-7) having a three-layer shape was taken out.
Using the obtained molded body (X-7), a desired mill blank part (7) was obtained in the same manner as in Example 1. This mill blank part (7) had a rectangular parallelepiped shape and a three-layer laminated structure, and its size was 14.9 mm x 18.4 mm x 15.5 mm.

[Comparative Example 3] Production of a mill blank having a two-layer laminated structure 2.18 g of powder (1) was filled onto the lower punch rod of a 14.7 x 18.2 mm rectangular press mold. , the powder was leveled by tapping. Next, the upper punch rod was installed at a predetermined position, and uniaxial pressing was performed using a press machine (press pressure: 15 MPa). After that, the upper punch rod was removed, and 2.18 g of powder (2) was filled on top of the powder (1) that had been uniaxially pressed. Next, the upper punch rod was placed in a predetermined position and the press A uniaxial press (press pressure: 60 MPa, time: 1 minute) was performed using a machine. Thereafter, the upper punch and the lower punch were removed from the mold, and a molded article (X-8) having a two-layer shape was taken out.
Using the obtained molded body (X-8), a desired mill blank part (8) was obtained in the same manner as in Example 1. This mill blank part (8) had a rectangular parallelepiped shape and a two-layer laminated structure, and its size was 14.9 mm x 18.4 mm x 15.5 mm.

[Measurement of compressive strength]
The compressive strength of the mill blank parts obtained in each Example and Comparative Example was measured by the following method. First, from the center of the 14.9 mm x 18.4 mm x 15.5 mm rectangular parallelepiped mill blank (the part indicated by the broken line in the column of compressive strength in Figure 5), a 3 mm x 3 mm x 3 mm cube was tested. Pieces were cut out using a diamond cutter. The compressive strength of the test piece was measured using an Autograph (manufactured by Shimadzu Corporation) at a crosshead speed of 2 mm/min. Note that the above measurements were performed with the test piece set so that force was applied from the direction in which the layers were laminated. Measurements were performed on each test piece obtained from 10 similarly prepared mill blank sections, and the average value was determined. The results are shown in Figure 5.

A mill blank with a laminated structure of two or more layers is an assembly of each layer, so the force from the direction in which the layers are laminated (typically the force from the occlusal surface in a dental prosthesis) is transferred from layer to layer. However, if the interface between the layers is curved, it will be transmitted in the direction of the curvature, that is, toward the outside of the mill blank and, ultimately, toward the outside of the dental prosthesis such as a crown obtained from the mill blank. Power can be dispersed. In addition, since it has a plurality of side surfaces (P) having curved interfaces, and at least two of the side surfaces (P) are not parallel to each other, a force is exerted not only in one direction but also in the other direction (preferably in a direction perpendicular thereto). can be dispersed. Therefore, it is thought that the mill blank having the structure of the present invention, and by extension the dental prosthesis obtained therefrom, exhibits high compressive strength and can improve mechanical strength in occlusion. In addition, it is thought that the force distribution due to the curvature of the interface between the layers can work more effectively as the three-dimensional symmetry of the interface increases. (5) showed higher compressive strength, and this effect was particularly remarkable in mill blank parts (1) and (3) of Examples 1 and 3, which had a layered shape curved from both the upper and lower sides. . The compressive strength is preferably 600 MPa or more, more preferably 620 MPa or more, and even more preferably 640 MPa or more. Although there is no particular limit to the upper limit of the compressive strength, the compressive strength can be, for example, 800 MPa or less.

[Measurement of chromaticity]
A position 7 mm from one end in the long side direction of a rectangular parallelepiped mill blank measuring 14.9 mm x 18.4 mm x 15.5 mm obtained in each example and comparative example (in Fig. 5, the chromaticity A chromaticity plate measuring 14.9 mm x 15.5 mm and 1.6 mm thick was cut out using a diamond cutter (ISOMET-1000) from the part indicated by the broken line in the column, and cut out using water-resistant abrasive paper (#1000, #2000, #3000) was used to make a thickness of 1.2 mm. Using the prepared chromaticity plate as a test piece, 11 points arranged linearly at 1.4 mm intervals across the interface were selected as measurement points (1st measurement point to 11th measurement point). Each chromaticity was measured using a color difference meter (Nippon Denshoku Kogyo Co., Ltd., spectrophotometer SE 6000, optical fiber φ4 mm), and the values of ΔL ^* , a ^* , and b ^* at each measurement point were determined. In addition, a ^* and b ^* are chromaticnesses in the CIE 1976 color system (L ^* a ^* b ^* color space; hereinafter referred to as "L ^* a ^* b ^* color system") measured with a spectrophotometer. and L ^* is the lightness index. △L ^* represents transparency, and the following formula;
△L ^* = L ^* W-L ^* B
(In the formula, L ^* W represents the lightness index L ^* in the L ^* a ^* b ^* color system measured on a white background, and L ^* B represents the lightness index L* in the L ^* a ^* b ^* color system measured on a black background. Represents the lightness index L ^* in the color system.)
This is the value calculated by Furthermore, the chromaticity change (ΔE ^* ) between two adjacent measurement points was determined using the values of ΔL ^* , a ^* , and b ^* at each measurement point. In addition, ΔE ^* is the following formula;
ΔE ^* = [(ΔΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² ] ^1/2
Calculated by.

The chromaticity measurement results for mill blank parts (1) to (8) of Examples 1 to 5 and Comparative Examples 1 to 3 are shown in FIGS. 6 to 13, respectively. Note that Figure A in Figures 6 to 10 schematically shows the measurement points, and the horizontal axis of each graph in Figures B to E in Figures 6 to 13 is the number of the 11 measurement points (Figure E indicates the smaller number of the two measurement points).
The chromaticity measurement results shown in FIGS. 6 to 10 for Examples 1 to 5 show no change in chromaticity compared to the chromaticity measurement results shown in FIGS. 11 to 13 for Comparative Examples 1 to 3. It can be seen that by using the mill blank having the mill blank parts (1) to (5) according to Examples 1 to 5, it is possible to manufacture a dental prosthesis having an appearance closer to the color tone of natural teeth.

Further, like the mill blank parts (1) to (5) of Examples 1 to 5, it has a plurality (4) of side surfaces (P) having curved interfaces, and at least two of the side surfaces (P) have a curved interface. Since they are not parallel to each other, a desired shape can be cut out from a wide range of parts, and a mill blank with excellent workability can be obtained. Furthermore, the mill blank having such a configuration is easy to manufacture, and the mill blank itself can be easily manufactured.

1 Chromaticity measurement start position (first measurement point)
11 Chromaticity measurement end position (11th measurement point)
2 Virtual first symmetry plane 3 Virtual second symmetry plane 4 Curved interface 5 Mill blank part

Claims (10)

A dental mill blank having a prismatic mill blank part having a laminated structure of two or more layers, the mill blank part having four side surfaces (P) having at least one curved interface,
The curvature of the interface on the four side surfaces (P) is unidirectional,
A mill blank in which the bottom surface perpendicular to the four side surfaces (P) does not include an interface . The mill blank according to claim 1 , wherein the prismatic shape is a quadrangular prism shape. The mill blank according to claim 1 or 2 , wherein the mill blank portion has an imaginary first plane of symmetry that equally divides the laminated structure, and the imaginary first plane of symmetry has at least one curved interface. The mill blank portion has a virtual second symmetry plane that is perpendicular to the virtual first symmetry plane and equally divides the laminated structure, and the virtual second symmetry plane has at least one curved interface. , the mill blank according to claim 3 . 1 . The shape of the curvature at the interface of the side surface (P) is selected from the group consisting of a circular arc shape, an elliptical arc shape, a parabola shape, a catenary shape, and a shape that is a combination of a plurality of these shapes. - The mill blank according to any one of 4 . The mill blank according to any one of claims 1 to 5 , wherein the adjacent layers in the laminated structure have different color tone and/or transparency. The mill blank according to any one of claims 1 to 6 , wherein the mill blank portion has a laminated structure of four or more layers. The mill blank according to any one of claims 1 to 7 , wherein all layers contain an inorganic filler (a). The method for manufacturing a mill blank according to any one of claims 1 to 8 , wherein the curved interface of the side surface (P) is formed by mechanical pressure ,
The mill blank is a dental mill blank having a prismatic mill blank portion having a laminated structure of two or more layers,
The mill blank part has four side surfaces (P) having at least one curved interface,
The curvature of the interface on the four side surfaces (P) is unidirectional,
The bottom surface perpendicular to the four side surfaces (P) does not include an interface;
How to manufacture mill blanks . A method for manufacturing a dental prosthesis, comprising the step of cutting the mill blank according to any one of claims 1 to 8 .

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