Abrasive blank and dental prosthesis, and method for producing same

Abstract

The invention relates to an abrasive blank and a dental prosthesis, and a method for preparing the same. The invention provides a grinding blank with a multi-layer structure and excellent aesthetics and a preparation method thereof. The present invention pertains to a dental polishing blank having a polishing blank part having a laminated structure of two or more layers, in which a main body layer (3) is present on the inside of an enamel layer (1), the main body layer (3) has a bottom surface and a side surface, and the side surface has a shape having a portion perpendicular to the bottom surface.

Description

[0001] This application is a divisional application of PCT patent application PCT / JP2018 / 047912, the title of which is "Abrasive blank and dental prosthesis, and method for producing the same", the parent application of which entered the Chinese application No. 201880083770.3. TECHNICAL FIELD

[0002] The present application relates to an abrasive blank and a method for producing the same. BACKGROUND

[0003] In the past, as a dental product (for example, a representative prosthesis such as a covering crown, a crown, a crown body, a denture, a product for orthodontic treatment, a product for dental implantation), a metal has been often used. However, the metal is significantly different in color from a natural tooth, has a disadvantage of lacking aesthetic appearance, and also has a problem of causing an allergic disease due to elution of the metal at times. Therefore, in order to solve the problems associated with the use of the metal, a ceramic material such as alumina (aluminum oxide), zirconia (zirconium oxide) is used for a dental product as a substitute material for the metal. In particular, zirconia is excellent in strength and also excellent in aesthetic appearance, and thus the demand has increased particularly with the recent reduction in price.

[0004] On the other hand, in order to further improve the aesthetic appearance in the oral cavity, it is necessary to make the appearance of the dental product similar to that of a natural tooth. However, it is difficult to reproduce the same appearance (particularly, transparency, luster (glossiness)) as that of a natural tooth with zirconia (sintered body) itself.

[0005] In Patent Literature 1, a resin-based dental abrasive blank in which a layer is laminated to form a curved surface is disclosed.

[0006] Further, Patent Literature 2 discloses a blank in which the inside of a block is composed of a material having ivory color and low light transmittance, and a material having high light transmittance corresponding to enamel surrounds the same.

[0007] PRIOR ART DOCUMENTS PATENT LITERATURE Patent Literature 1: Japanese Patent Application Laid-Open No. 2016-535610 Patent Literature 2: Japanese Patent Application Laid-Open No. 2014-534018. SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION A restoration prepared from a mill blank prepared by the preparation method according to Patent Document 1 is a structure like a fish cake having a gradient only in the front-rear direction (as a front tooth). In the case where a restoration having such a structure is used particularly for a front tooth, a portion having low light transmittance is formed inside the left and right ends of the tooth, the transparency and the color tone of the incisal edge portion cannot be reproduced, and the aesthetic property is poor. In addition, as a restoration, it is a restoration of the resin system, and there are problems in strength and durability. In addition, in terms of the preparation method, it is a preparation method using joining such as co-extrusion, sequential extrusion, sequential pressurization, or an additive structure, and it is not a simple preparation method.

[0009] In Patent Document 2, it is described that the material of the blank is ceramic or acrylate, but the specific preparation method is not described, and there is no description related to the specific name of the ceramic, the pre-calcination, the calcination, and the like.

[0010] According to the above, as the problem to be solved by the present application, the object is to provide a mill blank having a multi-layer structure with excellent aesthetic property and a preparation method thereof.

[0011] Means for solving the problem As a result of repeated and intensive research by the present inventors in order to solve the above problem, it was found that the above problem can be solved by having a specific multi-layer structure, and based on this insight, further research was conducted, thereby completing the present application.

[0012] That is, the present application relates to the following inventions.

[0013] [1] A mill blank for dental use, which is a mill blank having a mill blank portion, the mill blank portion having a laminated structure of 2 or more layers, in which a main body layer (3) is present inside an enamel layer (1), the main body layer (3) has a bottom surface and a side surface, and the side surface is a shape having a portion perpendicular to the bottom surface.

[0014] [2] The mill blank according to the preceding [1], in which the mill blank portion is a quadrangular prism shape.

[0015] [3] The mill blank according to the preceding [1] or [2], in which at least one cross section of the main body layer (3) parallel to the bottom surface is a shape having a profile obtained by combining at least 2 selected from a circular arc, an elliptical arc, a parabola, and a catenary.

[0016] [4] The mill blank according to any one of the preceding [1] to [3], in which at least one cross section of the main body layer (3) perpendicular to the bottom surface is a shape of a canister.

[0017] [5] The mill blank according to any one of the preceding [1] to [3], in which at least one cross section of the bottom surface perpendicular to the main body layer (3) is a convex shape.

[0018] [6] The mill blank according to any one of the preceding [1] to [5], wherein the mill blank portion has 1 or more intermediate layers (2) between the enamel layer (1) and the main body layer (3).

[0019] [7] The mill blank according to the preceding [6], wherein the intermediate layer (2) has a bottom surface and a side surface, and the side surface is a shape having a portion perpendicular to the bottom surface.

[0020] [8] The mill blank according to the preceding [7], wherein at least one cross section of the intermediate layer (2) parallel to the bottom surface is a cross-sectional shape obtained by combining at least 2 selected from a circular arc, an elliptical arc, a parabola, and a catenary.

[0021] [9] The mill blank according to the preceding [7] or [8], wherein at least one cross section of the intermediate layer (2) perpendicular to the bottom surface is a shape of a canister.

[0022]

[10] The mill blank according to the preceding [7] or [8], wherein at least one cross section of the intermediate layer (2) perpendicular to the bottom surface is a convex shape.

[0023]

[11] The mill blank according to any one of the preceding [1] to

[10] , wherein the hue and / or the light transmittance of each of the adjacent layers in the layered structure are different from each other.

[0024]

[12] The mill blank according to any one of the preceding [1] to

[11] , wherein the chroma in the L*a*b* color system of the main body layer (3) is L* = 60 to 85, a* = -2 to 7, and b* = 4 to 28.

[0025]

[13] The mill blank according to any one of the preceding [1] to

[12] , wherein the light transmittance of the main body layer (3) is ΔL* = 2 to 13.

[0026]

[14] The mill blank according to any one of the preceding [1] to

[13] , wherein the chroma in the L*a*b* color system of the enamel layer (1) is L* = 62 to 90, a* = -3 to 5, and b* = 3 to 22.

[0027]

[15] The mill blank according to any one of the preceding [1] to

[14] , wherein the light transmittance of the enamel layer (1) is ΔL* = 4 to 20.

[0028]

[16] The mill blank according to any one of the preceding [6] to

[15] , wherein the chroma in the L*a*b* color system of the intermediate layer (2) is L* = 62 to 86, a* = -2 to 7, and b* = 4 to 27.

[0029]

[17] The mill blank according to any one of the preceding [6] to

[16] , wherein the intermediate layer (2) has a light transmittance of ΔL* = 4 to 18.

[0030]

[18] The mill blank according to any one of the preceding [1] to

[17] , wherein the mill blank portion comprises a zirconia precalcined body.

[0031]

[19] A dental restoration comprising the mill blank according to any one of the preceding [1] to

[18] .

[0032]

[20] A method for producing the mill blank according to any one of the preceding [1] to

[18] , comprising the steps of pre-forming the main layer (3) by a powder pressing method, covering the main layer (3) forming a pre-formed body with the enamel layer (1), and performing a final pressing molding.

[0033]

[21] The method for producing the mill blank according to the preceding

[20] , comprising the step of forming the main layer (3) so as to have a bottom surface and a side surface, and the side surface is in a shape having a portion perpendicular to the bottom surface, and at least one cross section perpendicular to the bottom surface forms a shape of a canister.

[0034]

[22] The method for producing the mill blank according to any one of the preceding [6] to

[17] , comprising the steps of pre-forming the main layer (3) and the intermediate layer (2) by a powder pressing method, covering the main layer (3) and the intermediate layer (2) forming a pre-formed body with the enamel layer (1), and performing a final pressing molding.

[0035]

[23] The method for producing the mill blank according to the preceding

[22] , comprising the step of forming the main layer (3) and / or the intermediate layer (2) so as to have a bottom surface and a side surface, and the side surface is in a shape having a portion perpendicular to the bottom surface, and at least one cross section perpendicular to the bottom surface forms a shape of a canister.

[0036]

[24] A method for producing a dental restoration, comprising the step of subjecting the mill blank according to any one of the preceding [1] to

[18] to cutting processing.

[0037] Effects of the Invention By the present invention, a mill blank having a multi-layer structure, a dental restoration, and a method for producing the same, which are excellent in appearance, can be provided. That is, by the present invention, a mill blank having a multi-layer structure, a dental restoration, and a method for producing the same, which have a color tone and a light transmittance close to natural teeth, can be provided. Furthermore, by the present invention, a mill blank having a multi-layer structure, a dental restoration, and a method for producing the same, which are excellent in strength and durability, can be provided. Further, by the method for producing the present invention, a mill blank and a dental restoration can be easily produced. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a schematic view showing an example of an embodiment of the grinding blank portion to which the present application is applied.

[0039] Figure 2A is a cross-sectional view (schematic view) of the grinding blank portion to which the present application is applied when cut with an imaginary first cutting plane.

[0040] Figure 2B is a cross-sectional view (schematic view) of the grinding blank portion to which the present application is applied when cut with an imaginary first cutting plane.

[0041] Figure 2C is a cross-sectional view (schematic view) of the grinding blank portion to which the present application is applied when cut with an imaginary first cutting plane.

[0042] Figure 2D is a cross-sectional view (schematic view) of the grinding blank portion to which the present application is applied when cut with an imaginary first cutting plane.

[0043] Figure 3A is a cross-sectional view (schematic view) of the grinding blank portion to which the present application is applied when cut with an imaginary second cutting plane.

[0044] Figure 3B is a cross-sectional view (schematic view) of the grinding blank portion to which the present application is applied when cut with an imaginary second cutting plane.

[0045] Figure 3C is a cross-sectional view (schematic view) of the grinding blank portion to which the present application is applied when cut with an imaginary second cutting plane.

[0046] Figure 3D is a cross-sectional view (schematic view) of the grinding blank portion to which the present application is applied when cut with an imaginary second cutting plane.

[0047] Figure 4 is a schematic view showing an example of an embodiment of the grinding blank portion to which the present application is applied.

[0048] Figure 5A is a cross-sectional view (schematic view) of the grinding blank portion to which the present application is applied when cut with an imaginary first cutting plane.

[0049] Figure 5B is a cross-sectional view (schematic view) of the grinding blank portion to which the present application is applied when cut with an imaginary first cutting plane.

[0050] Figure 5C is a cross-sectional view (schematic view) of the grinding blank portion to which the present application is applied when cut with an imaginary first cutting plane.

[0051] Figure 5Dis a cross-sectional view (schematic view) when the grinding blank portion related to the present application is cut with an imaginary first cut surface.

[0052] Figure 6A is a cross-sectional view (schematic view) when the grinding blank portion related to the present application is cut with an imaginary second cut surface.

[0053] Figure 6B is a cross-sectional view (schematic view) when the grinding blank portion related to the present application is cut with an imaginary second cut surface.

[0054] Figure 6C is a cross-sectional view (schematic view) when the grinding blank portion related to the present application is cut with an imaginary second cut surface.

[0055] Figure 6D is a cross-sectional view (schematic view) when the grinding blank portion related to the present application is cut with an imaginary second cut surface.

[0056] Figure 7 is a cross-sectional view (schematic view) when the grinding blank portion related to the present application is cut with an imaginary second cut surface.

[0057] Figure 8 is a cross-sectional view (schematic view) when the grinding blank portion related to the present application is cut with an imaginary second cut surface.

[0058] Figure 9 is a cross-sectional view (schematic view) when the grinding blank portion related to the present application is cut with an imaginary second cut surface.

[0059] Figure 10 is a cross-sectional view (schematic view) when the grinding blank portion related to the present application is cut with an imaginary second cut surface.

[0060] Figure 11 is a cross-sectional view (schematic view) when the grinding blank portion related to the present application is cut with an imaginary second cut surface. DETAILED DESCRIPTION

[0061] The grinding blank of the present application is a dental grinding blank having a grinding blank portion having a laminated structure of two or more layers, characterized in that, in the laminated structure, a body layer (3) is present on the inner side of an enamel layer (1), the body layer (3) has a bottom surface and a side surface, and the side surface is in a shape having a portion perpendicular to the bottom surface.

[0062] [Grinding blank portion] The grinding blank portion in the present application has a laminated structure of two or more layers including an enamel layer (1) and a body layer (3). An example of the grinding blank portion is shown in Figure 1 .

[0063] The main body layer (3) is a color-masking layer to prevent the color of the base tooth from showing in the polishing blank, and needs to be formed inside the enamel layer. The main body layer (3) has a bottom surface and a side surface, and the side surface has a shape with a portion perpendicular to the bottom surface, thereby forming a structure (enamel) that is closer to that of a natural tooth, thus obtaining the same color as a natural tooth. In addition, the aforementioned side surface has a shape with a portion perpendicular to the bottom surface, thereby allowing the internal structure of the polishing blank to be measured and easily reflected in CAD software. That is, in CAD software, the alignment of the dental restoration within the hypothetical polishing blank becomes easier. The side surface of the main body layer (3) in the polishing blank, with the portion perpendicular to the bottom surface, has a desired height to be closer to the enamel. It should be noted that the bottom surface of the main body layer (3) can be covered by the enamel layer (1), the intermediate layer (2) described later, or exposed to the surface of the polishing blank.

[0064] The suitable shape for the main body layer (3) will be explained below.

[0065] In the main body layer (3), at least one cross-section parallel to the bottom surface is preferably a shape having a profile obtained by combining at least two of the following: circular arc, elliptical arc, parabola, and pendant. This profile may be a combination of straight lines, in addition to curves selected from circular arc, elliptical arc, parabola, and pendant; more preferably, it may be a profile obtained by combining only curves selected from circular arc, elliptical arc, parabola, and pendant. Examples of such shapes include circles and ellipses. Figures 2A-2D The shape described herein. It should be noted that, as the aforementioned cross-section, for example, includes... Figure 1 The imaginary first cutting surface (4) is the cross section during cutting.

[0066] In the main body layer (3), at least one cross-section perpendicular to the bottom surface is preferably in the shape of a projectile. A projectile shape refers to, for example, in a cross-section... Figure 1 In the case where the imaginary second cut surface (5) cuts the grinding blank, representing the shape of a quadrilateral with one side bent outward, the main body layer (3) can be illustrated. Figures 3A-3D The main body layer described in the figure (the diagonally lined part in Figure 3) (A~D in Figure 3 correspond to A~D in Figure 2 respectively). Furthermore, the main body layer (3) may have... Figures 7-11 The shape described in the text. For example, as... Figures 7-10 As shown, the main body layer (3) can be in the shape of having steps (shoulder 6). Furthermore, in addition to having steps, in... Figure 1 In the hypothetical second cutting surface (5), the cross-section (at least one cross-section of the main body layer (3) perpendicular to the bottom surface) during cutting can also be a main body layer with multiple portions perpendicular to the bottom surface on the side and a convex shape. In other words, as Figures 7-10 As shown, the main body layer (3) can partially have a cylindrical or other columnar shape. The aforementioned columnar shape is as follows...Figure 8 and Figure 10 As shown in FIG. 1, the convex shape of the corner of the column can have a circular arc when the cross section (at least one cross section of the body layer (3) perpendicular to the bottom surface) at the time of cutting by the imaginary second cutting plane (5) in FIG. 1 is cut. Figure 1 The body layer (3) has the above-described shape, and thus can be closer to the structure of a natural tooth. Note that, as the aforementioned cross section, for example, a cross section at the time of cutting by the imaginary second cutting plane (5) in FIG. 1 is included. Figure 1 The body layer (3) has the above-described shape, and thus can be closer to the structure of a natural tooth. Note that, as the aforementioned cross section, for example, a cross section at the time of cutting by the imaginary second cutting plane (5) in FIG. 1 is included.

[0067] The polishing blank of the present application preferably has one or more intermediate layers (2) between the enamel layer (1) and the body layer (3). By having one or more intermediate layers (2), the color tone of the body layer can be prevented from appearing on the surface. An example of the polishing blank is shown in FIG. 2. Figure 4

[0068] The intermediate layer (2) needs to cover at least a part of the side surface of the body layer (3), and as a preferred embodiment, the intermediate layer (2) covers the entire side surface of the body layer (3). In addition, the intermediate layer (2) can cover the entire or at least a part of the bottom surface of the body layer (3).

[0069] The suitable shape of the intermediate layer (2) is described below.

[0070] The intermediate layer (2) preferably has a bottom surface and a side surface, and the side surface is a shape having a portion perpendicular to the bottom surface. Thereby, the same structure (tooth enamel) as a natural tooth is obtained, and thus the same color tone as a natural tooth is obtained. In addition, the aforementioned side surface is a shape having a portion perpendicular to the bottom surface, and thus the internal structure of the polishing blank can be measured, and can be easily reflected in the CAD software. That is, in the CAD software, the alignment of the dental prosthesis within the polishing blank becomes easy.

[0071] In the intermediate layer (2), at least one cross section parallel to the bottom surface is preferably a shape having a profile obtained by combining at least two selected from a circular arc, an elliptical arc, a parabola, and a catenary. The profile can be a profile obtained by combining straight lines in addition to the curves selected from a circular arc, an elliptical arc, a parabola, and a catenary, and is more preferably a profile obtained by combining only the curves selected from a circular arc, an elliptical arc, a parabola, and a catenary. As the aforementioned shape, shapes described in the above-mentioned cross section can be exemplified. Figures 5A-5D In the intermediate layer (2), at least one cross section parallel to the bottom surface is preferably a shape having a profile obtained by combining at least two selected from a circular arc, an elliptical arc, a parabola, and a catenary. The profile can be a profile obtained by combining straight lines in addition to the curves selected from a circular arc, an elliptical arc, a parabola, and a catenary, and is more preferably a profile obtained by combining only the curves selected from a circular arc, an elliptical arc, a parabola, and a catenary. As the aforementioned shape, shapes described in the above-mentioned cross section can be exemplified. Figure 4 In the intermediate layer (2), at least one cross section parallel to the bottom surface is preferably a shape having a profile obtained by combining at least two selected from a circular arc, an elliptical arc, a parabola, and a catenary. The profile can be a profile obtained by combining straight lines in addition to the curves selected from a circular arc, an elliptical arc, a parabola, and a catenary, and is more preferably a profile obtained by combining only the curves selected from a circular arc, an elliptical arc, a parabola, and a catenary. As the aforementioned shape, shapes described in the above-mentioned cross section can be exemplified.

[0072] In the intermediate layer (2), at least one cross section perpendicular to the bottom surface is preferably a shape of a shell. As the intermediate layer (2) of the shape of a shell, shapes described in the above-mentioned cross section can be exemplified. Figures 6A-6D ​The intermediate layer described in the figure (A~D in Figure 6 correspond to A~D in Figure 5). Furthermore, it can be... Figure 7 , 8 The portion of the enamel layer (1) inside the main body layer (3) has one or more intermediate layers (2). The intermediate layers (2) have the aforementioned shape, thereby more closely resembling the structure of a natural tooth. It should be noted that, for example, the aforementioned cross-section includes... Figure 4 The imaginary second cutting surface (5) is the cross section during cutting.

[0073] The shape of the intermediate layer (2) may be the same as or different from that of the main layer (3), but from the viewpoint of shielding the base teeth, the same shape is preferred.

[0074] The shape of the grinding blank portion of the present invention is not particularly limited as long as the fixture is installed. In both embodiments with and without the intermediate layer (2), it can be, for example, prism-shaped. From a manufacturing point of view, it is preferred to be quadrangular prism-shaped.

[0075] Suitable embodiments for hue and translucency in each layer will be described below. It should be noted that, as a measure of hue in this invention, chromaticity values ​​such as L*, a*, and b* in the L*a*b* color system can be used. As a measure of translucency, chromaticity values ​​such as ΔL* in the L*a*b* color system can be used. It should be noted that, as described later, when the grinding blank of this invention is a zirconia pre-calcined body, the aforementioned hue (chromaticity) and translucency refer to values ​​after sintering. Details of their measurement methods are described in the embodiments described later.

[0076] The preferred chromaticity of the L*a*b* color system in the main layer (3) is L*=60~85, a*=-2~7, b*=4~28, and more preferably L*=64~77, a*=-1~4, b*=11~27.

[0077] The light transmittance ΔL* of the main layer (3) is preferably 2 to 13, more preferably 2 to 10, and even more preferably 3 to 7. By improving the hue opacity by satisfying the aforementioned range of light transmittance, a hue equivalent to that of natural teeth can be obtained.

[0078] In the glaze layer (1), the preferred chromaticity of the L*a*b* color system is L*=62~90, a*=-3~5, b*=3~22, more preferably L*=62~72, a*=-2~2, b*=5~19, and even more preferably L*=68~72, a*=-2~2, b*=5~19.

[0079] The light transmittance ΔL* of the enamel layer (1) is preferably 4 to 20, more preferably 7 to 20. Further, in an embodiment, the light transmittance ΔL* of the enamel layer (1) is more preferably 4 to 18, further preferably 7 to 18, particularly preferably 8 to 16. By making the light transmittance satisfy the aforementioned range, a mill blank portion with excellent aesthetic properties can be produced.

[0080] In the intermediate layer (2), the chromaticity in the L*a*b* color system is preferably L* = 62 to 86, a* = -2 to 7, b* = 4 to 27, more preferably L* = 63 to 76, a* = -1 to 4, b* = 10 to 26.

[0081] The light transmittance ΔL* of the intermediate layer (2) is preferably 4 to 18, more preferably 5 to 17, further preferably 6 to 11. By making the light transmittance satisfy the aforementioned range, the hue of the body layer (3) can be appropriately brought to the surface.

[0082] The mill blank portion of the present application is preferably such that the hue and / or light transmittance of each layer adjacent to each other in the layered structure are different from each other from the viewpoint of closeness to the appearance of a natural tooth. For example, as shown in Figure 1 In the embodiment (x-1) having no intermediate layer (2), the light transmittance is preferably such that the mill blank portion satisfies the relationship of the light transmittance ΔL* of the body layer (3) < the light transmittance ΔL* of the enamel layer (1) from the viewpoint of closeness to the appearance of a natural tooth. As another suitable embodiment (x-2), in the aforementioned embodiment (x-1), the difference between the light transmittance ΔL* of the enamel layer (1) and the light transmittance ΔL* of the body layer (3) is preferably 1 to 9, more preferably 2 to 8, further preferably 3 to 7. As another suitable embodiment (x-3), in the aforementioned embodiment (x-1), the mill blank portion is preferably such that the L* value, a* value, and b* value of the enamel layer (1) < the L* value, a* value, and b* value of the body layer (3) are satisfied from the viewpoint of closeness to the appearance of a natural tooth.

[0083] Further, as shown in Figure 4In the embodiment (y-1) having the intermediate layer (2) in addition to the enamel layer (1) and the main body layer (3), from the viewpoint of closeness to the appearance of a natural tooth, it is preferable that the ground blank satisfy the relationship of the light transmittance ΔL* of the main body layer (3) < the light transmittance ΔL* of the intermediate layer (2) < the light transmittance ΔL* of the enamel layer (1) with respect to the light transmittance. As another suitable embodiment (y-2), in the aforementioned embodiment (y-1), from the viewpoint of closeness to the appearance of a natural tooth, it is preferable that the ground blank satisfy the relationship of the L* value, the a* value, and the b* value of the enamel layer (1) < the L* value, the a* value, and the b* value of the main body layer (3). Further, as another suitable embodiment (y-3), in the aforementioned embodiment (y-1) or (y-2), from the viewpoint of closeness to the appearance of a natural tooth, it is preferable that the ground blank satisfy the relationship of the L* value, the a* value, and the b* value of the enamel layer (1) < the L* value, the a* value, and the b* value of the intermediate layer (2). As another suitable embodiment (y-4), in the aforementioned embodiment (y-1) to (y-3), from the viewpoint of closeness to the appearance of a natural tooth, it is preferable that the ground blank satisfy the relationship of the L* value of the enamel layer (1) < the L* value of the main body layer (3) < the L* value of the intermediate layer (2) with respect to the L* value. In addition, as another suitable embodiment (y-5), in the aforementioned embodiment (y-1) to (y-4), from the viewpoint of closeness to the appearance of a natural tooth, it is particularly preferable that the ground blank satisfy the relationship of the L* value of the enamel layer (1) < the L* value of the main body layer (3) < the L* value of the intermediate layer (2) with respect to the L* value, the relationship of the a* value of the enamel layer (1) < the a* value of the intermediate layer (2) < the a* value of the main body layer (3) with respect to the a* value and the b* value, the relationship of the b* value of the enamel layer (1) < the b* value of the intermediate layer (2) < the b* value of the main body layer (3) with respect to the b* value, and the relationship of the light transmittance ΔL* of the main body layer (3) < the light transmittance ΔL* of the intermediate layer (2) < the light transmittance ΔL* of the enamel layer (1) with respect to the light transmittance. In the aforementioned embodiment (y-1) to (y-5), the difference between the light transmittance ΔL* of the enamel layer (1) and the light transmittance ΔL* of the intermediate layer (2) is preferably 1 to 9, more preferably 2 to 8, and further preferably 3 to 7. In addition, in the aforementioned embodiment (y-1) to (y-5), the difference between the light transmittance ΔL* of the intermediate layer (2) and the light transmittance ΔL* of the main body layer (3) is preferably 1 to 9, more preferably 2 to 8, and further preferably 3 to 7.

[0084] The ground blank portion of the present application can be composed of a ceramic such as zirconia or glass, or a resin. From the viewpoint of strength and durability, it is preferable that the ground blank portion be composed of zirconia. From the viewpoint of ease of processing, it is more preferable that the ground blank portion be composed of a zirconia pre-calcined body.

[0085] The aforementioned zirconia pre-calcined body preferably contains a pigment or an additive in order to satisfy the suitable color tone and light transmittance of each layer.

[0086] As the aforementioned pigments, publicly known pigments (inorganic pigments, composite pigments, fluorescent pigments, etc.) used in dental compositions can be used. As the inorganic pigments, oxides such as nickel oxide, red iron oxide, chromium oxide, aluminum oxide, titanium oxide, etc. can be given. Further, as the composite pigments, Zr-V, Fe(Fe, Cr)2O4, (Ni, Co, Fe)(Fe, Cr)2O4-ZrSiO4, (Co, Zn)Al2O4, etc. can be given. As the fluorescent pigments, Y2SiO5:Ce, Y2SiO5:Tb, (Y, Gd, Eu)BO3, Y2O3:Eu, YAG:Ce, ZnGa2O4:Zn, BaMgAl 10 O 17 :Eu, etc. can be given.

[0087] The aforementioned zirconia pre-calcine in terms of the breakage resistance and the crack resistance, which are required to be able to withstand the degree of repeated mastication movements as a dental product, and the bending strength, it is preferable to contain a stabilizer. That is, it is preferable to contain a stabilizer in the zirconia before calcination. Thereby, the zirconia sintered body after calcination, which becomes a base material of a dental product, can have at least one of partially stabilized zirconia and fully stabilized zirconia as a matrix phase. In the aforementioned zirconia sintered body, the main crystal phase of the zirconia is at least one of tetragonal crystal and cubic crystal, and both of the tetragonal crystal and the cubic crystal can be contained. Further, the aforementioned zirconia sintered body is preferably substantially free of monoclinic crystal. Substantially free of monoclinic crystal means that the content of the monoclinic crystal in the zirconia sintered body is less than 5.0 mass%, preferably less than 1.0 mass%. It should be noted that the zirconia which is partially stabilized by adding a stabilizer is referred to as partially stabilized zirconia (PSZ; Partially Stabilized Zirconia), and the zirconia which is fully stabilized is referred to as fully stabilized zirconia.

[0088] As the aforementioned stabilizer, it is preferable to be at least one kind of oxide selected from yttrium oxide (Y2O3) (hereinafter referred to as "yttrium oxide"), titanium oxide (TiO2), calcium oxide (calcium oxide; CaO), magnesium oxide (magnesium oxide; MgO), cerium oxide (cerium oxide; CeO2), aluminum oxide (aluminum oxide; Al2O3), scandium oxide (Sc2O3), lanthanum oxide (La2O3), erbium oxide (Er2O3), praseodymium oxide (Pr6O 11 ), samarium oxide (Sm2O3), europium oxide (Eu2O3), and thulium oxide (Tm2O3). In particular, from the viewpoint of high light transmittance and strength improvement, as the stabilizer, yttrium oxide is preferable. They can be used alone as one kind, or two or more kinds in combination.

[0089] In the case where the stabilizer contains yttria, the content of yttria is preferably 2 to 8 mol%, more preferably 3 to 6 mol% in 100 mol% in total of the zirconia and the stabilizer. If it is this content, it is possible to increase the transparency of the zirconia sintered body while suppressing the phase transition to monoclinic crystal.

[0090] In the case where the stabilizer contains titania, the content of titania is preferably 0.1 to 1 mol%, more preferably 0.1 to 0.3 mol% in 100 mol% in total of the zirconia and the stabilizer.

[0091] In the case where the stabilizer contains calcium oxide, the content of calcium oxide is preferably 2 to 15 mol%, more preferably 2.1 to 12 mol% in 100 mol% in total of the zirconia and the stabilizer.

[0092] In the case where the stabilizer contains magnesium oxide, the content of magnesium oxide is preferably 2 to 12 mol%, more preferably 2.1 to 10 mol% in 100 mol% in total of the zirconia and the stabilizer.

[0093] In the case where the stabilizer contains ceria, the content of ceria is preferably 2 to 18 mol%, more preferably 2.1 to 12 mol% in 100 mol% in total of the zirconia and the stabilizer.

[0094] In the case where the stabilizer contains alumina, the content of alumina is preferably 0.1 to 1 mol%, more preferably 0.1 to 0.3 mol% in 100 mol% in total of the zirconia and the stabilizer.

[0095] In the case where the stabilizer contains scandia, the content of scandia is preferably 0.1 to 1 mol%, more preferably 0.1 to 0.3 mol% in 100 mol% in total of the zirconia and the stabilizer.

[0096] In the case where the stabilizer contains lanthana, the content of lanthana is preferably 1 to 10 mol%, more preferably 2 to 7 mol% in 100 mol% in total of the zirconia and the stabilizer.

[0097] In the case where the stabilizer contains erbium oxide, the content of erbium oxide is preferably 0.1 to 1 mol%, more preferably 0.1 to 0.3 mol% in 100 mol% in total of the zirconia and the stabilizer.

[0098] In the case where the stabilizer contains praseodymia, the content of praseodymia is preferably 0.1 to 1 mol%, more preferably 0.1 to 0.3 mol% in 100 mol% in total of the zirconia and the stabilizer.

[0099] In the case where the samarium oxide is contained as the stabilizer, the content of the samarium oxide is preferably 0.1 to 1 mol%, more preferably 0.1 to 0.3 mol% in 100 mol% in total of the zirconia and the stabilizer.

[0100] In the case where the europium oxide is contained as the stabilizer, the content of the europium oxide is preferably 0.1 to 1 mol%, more preferably 0.1 to 0.3 mol% in 100 mol% in total of the zirconia and the stabilizer.

[0101] In the case where the thulium oxide is contained as the stabilizer, the content of the thulium oxide is preferably 0.1 to 1 mol%, more preferably 0.1 to 0.3 mol% in 100 mol% in total of the zirconia and the stabilizer.

[0102] Note that the content of the stabilizer in the zirconia sintered body can be measured by, for example, inductively coupled plasma (ICP) emission spectrometry, fluorescence X-ray analysis, or the like.

[0103] The production method of the abrasive blank according to the present application will be described below.

[0104] The production method of the abrasive blank according to the present application includes the steps of pre-forming the main layer (3) by a powder press method, covering the main layer (3) forming a pre-formed body with the vitreous layer (1), and performing a final press forming.

[0105] The aforementioned powder press method refers to a method of preparing a powder in which a powder (for example, zirconia powder in the case of producing the main layer (3)) constituting a layer, and a pigment, an additive, or the like are mixed, and performing press forming using a punch in a mold.

[0106] The pressurization at the pre-forming can use conventionally known conditions, and the pressurization pressure needs to be set to a condition lower than that of the subsequent final press forming. The density of the obtained formed body (abrasive blank portion) is preferably 2.0 to 4.0 g / cm 3 The device and the conditions of the final press forming are not limited as long as the density can be achieved.

[0107] In the present application, in the case where the intermediate layer (2) is provided in the abrasive blank portion, it is preferable to include the steps of pre-forming the main layer (3) and the intermediate layer (2) by a powder press method, covering the main layer (3) and the intermediate layer (2) forming a pre-formed body with the vitreous layer (1), and performing a final press forming. It is more preferable to include the steps of pre-forming the main layer (3) by a powder press method, pre-forming the obtained main layer (3) with the intermediate layer (2), covering the main layer (3) and the intermediate layer (2) forming a pre-formed body with the vitreous layer (1), and performing a final press forming.

[0108] The pressing pressure at the pre-molding of the main layer (3) is set to a lower condition than at the pre-molding of the intermediate layer (2), and the pressure at the pre-molding of the intermediate layer (2) is set to a lower condition than at the subsequent formal press molding.

[0109] The density of the obtained molded body (milling blank portion) is preferably 2.0 to 4.0 g / cm 3 The device and conditions of the formal press molding are not limited as long as the density can be achieved.

[0110] In the milling blank portion of the present application, in order to obtain the main layer (3) having a specific shape, the pressing can be performed using a mold having the shape in the pre-molding of the main layer (3), or the pre-molded body can be finished to the shape by cutting after the pressing using a general mold. As the shape, as described above, the main layer (3) has a bottom surface and a side surface, and the side surface has a shape having a portion perpendicular to the bottom surface, and at least one cross section perpendicular to the bottom surface in the main layer (3) is preferably a shape of a canister, and in the method for producing the milling blank of the present application, a step of molding the main layer (3) to the shape is preferably included.

[0111] In order to also obtain the intermediate layer (2) having a specific shape, the pressing can be performed using a mold having the shape in the pre-molding of the intermediate layer (2), or the pre-molded body can be finished to the shape by cutting after the pressing using a general mold. As the shape, as described above, the intermediate layer (2) has a bottom surface and a side surface, and the side surface has a shape having a portion perpendicular to the bottom surface, and at least one cross section perpendicular to the bottom surface in the intermediate layer (2) is preferably a shape of a canister, and in the method for producing the milling blank of the present application, a step of molding the intermediate layer (2) to the shape is preferably included.

[0112] [Mill blank] The mill blank of the present application has the aforementioned milling blank portion, and preferably has the milling blank portion and a support portion. By the support portion, the mill blank can be fixed to a milling device. The method of mounting the support portion on the milling blank portion is not particularly limited, and the milling blank portion and the support portion can be bonded, for example, by an adhesive or the like.

[0113] The mill blank of the present application is used for dental applications, and for example, can be suitably used for dental prostheses such as inlays, onlays, veneers, crowns, bridges, abutments, dental posts, dentures, denture beds, implant members (fixing members, abutments), and the like, which are produced by cutting processing using a dental CAD / CAM system. The method for producing a dental prosthesis from the mill blank of the present application is not particularly limited, and a publicly known method can be appropriately used, and preferably includes a step of cutting processing the mill blank.

[0114] As long as the effects of the present invention are achieved, within the scope of the technical concept of the present invention, the present invention includes various embodiments obtained by combining the above-described components. Example

[0115] Next, embodiments will be given to further illustrate the present invention. However, the present invention is not limited by these embodiments in any way. Within the scope of the technical concept of the present invention, those skilled in the art can make various modifications.

[0116] [Example 1] Zirconia powder containing 6 mol% yttrium oxide as a stabilizer was prepared and added to a cylindrical mold with a diameter of approximately 11 mm, such that the height of the pressurized main body layer (3) reached 8 mm, along with the amount of pigment listed in Table 1. Next, the zirconia powder was pre-formed under pressure of 3 kN, and the resulting pre-formed main body layer (3) was cut to form... Figure 4 The shell shape described in the text. Then, a preform of the aforementioned main body layer (3) was placed in a cylindrical mold with a diameter of approximately 14 mm. The same zirconium oxide powder used in the main body layer (3) was added around the preform of the aforementioned main body layer (3) along with the amount of pigment described in Table 1, so that the height of the intermediate layer (2) after pressure reached 12 mm. Next, the zirconium oxide powder was preformed under pressure of 5 kN, and the resulting preforms of the main body layer (3) and intermediate layer (2) were cut to form... Figure 4 The cannonball shape described in the text. Subsequently, a preform of the aforementioned main body layer (3) and intermediate layer (2) was placed in a 18.4mm × 20.3mm quadrangular prism mold. The same zirconia powder used in the main body layer (3) and intermediate layer (2) was added around the preform of the aforementioned main body layer (3) and intermediate layer (2) along with the amount of pigment described in Table 1, so that the height of the glaze layer (1) after pressure is 14mm. Next, the zirconia powder was formally pressurized at 30kN and then subjected to CIP (Cold Isostatic Pressing) treatment at 170MPa for 1 minute to produce a polished blank. Next, using the calcination furnace "Noritakekatana (registered trademark) F-1" manufactured by SK Medial Electronics Co., Ltd., the grinding blank was calcined at 1,025°C for 2 hours to produce a grinding blank containing a zirconia pre-calcined body.

[0117] A method for producing a zirconia sintered body frame will be described. First, an impression material called an impression material is used to take a negative mold of a base tooth, its opposing tooth, and the dentition around the base tooth. Next, plaster is flowed into the negative mold to produce a plaster model of the positive mold, reproducing the base tooth, its opposing tooth, and the dentition around the base tooth. Next, a wax crown having the same occlusion, shape, size, and the like as the base tooth of the plaster model is formed using wax. This wax crown becomes the basis for the frame. Next, the base tooth of the plaster model and the wax crown are optically scanned using a "Cattana (registered trademark) Dental Scanner D750" manufactured by Kureha Noritake Dental Corp. to obtain digitized three-dimensional data of the base tooth and the wax crown. Note that in this embodiment, the plaster model is optically scanned, but the inside of the mouth can also be optically scanned directly using an intraoral scanner. Alternatively, the plaster model can be optically scanned without using a wax crown, and three-dimensional data can be produced based on an assumed frame shape using three-dimensional CAD software.

[0118] Next, the ground blank portion containing the zirconia pre-sintered body produced is machined into a frame shape for anterior teeth using a grinding machine "DWX-50N" manufactured by Kureha Noritake Dental Corp. based on the aforementioned three-dimensional data using a φ2.0 mm and φ0.8 mm superhard drill. Thereafter, the frame for anterior teeth containing a zirconia sintered body is produced by sintering at 1550°C for 2 hours using a sintering furnace "Noritake Cattana (registered trademark) F-1" manufactured by SK Medical Electronics Co., Ltd.

[0119] The remaining portion remaining on the surface of the resulting frame for anterior teeth is removed using an electric cutting tool with an axial diamond abrasive. Next, the surface of the frame for anterior teeth is subjected to a sandblasting treatment using 50 μm alumina at a pressure of 0.2 MPa to set the surface in a matte state. Thereafter, the surface of the frame for anterior teeth is polished using "Pearl Surface (registered trademark)" manufactured by Kureha Noritake Dental Corp. to impart a gloss to the surface, thereby producing a dental restoration of the present application.

[0120] [Example 2] A dental restoration of the present application was produced in the same manner as in Example 1 except that the pigments at the time of producing each layer were changed to the amounts described in Table 1.

[0121] [Comparative Example 1] As a raw material of the frame, a commercially available "NORITAKE KATANA (registered trademark) Zirconia" disc of 98.5 mm x 14.0 mm manufactured by NORITAKE DENTAL CORPORATION, which is a parallel 4-layer laminated structure and does not have a portion perpendicular to the bottom surface on the side of the main body layer (3), was prepared. Next, based on the three-dimensional data obtained in Example 1, the disc was processed into a frame shape by φ 2.0 mm and φ 0.8 mm superhard drills using a processing machine "DWX-50N" manufactured by NORITAKE DENTAL CORPORATION. Using the processed frame as a precursor, a sintering was performed by firing at 1550°C for 2 hours using a calcination furnace "NORITAKE KATANA (registered trademark) F-1" manufactured by SK MEDICAL ELECTRONICS CO., LTD., and a front tooth frame was produced.

[0122] The remaining portions remaining on the surface of the obtained front tooth frame were removed using an electric cutting tool with an axial diamond abrasive. Next, the surface of the front tooth frame was subjected to a sandblasting treatment using 50 μm alumina at a pressure of 0.2 MPa to set the surface of the front tooth frame in a matte state. Thereafter, the surface of the front tooth frame was polished using "PEARL SURFACE (registered trademark)" manufactured by NORITAKE DENTAL CORPORATION to have a gloss, and a dental prosthesis was produced.

[0123] 〔Measurement of color tone〕 For the color tone, each layer of the dental prosthesis produced in each of the examples and comparative examples was used individually to produce a single-layer zirconia sintered body, which was processed in a manner to form a circular plate having a diameter of 14 mm and a thickness of 1.2 mm (both sides #600 polishing), and then the chromaticity in the L*a*b* color system (JIS Z 8781-4:2013 Colorimetry - Part 4: CIE 1976 L*a*b* color space) was measured using a spectrophotometer CM-3610A manufactured by Konica Minolta, Inc. under the conditions of D65 light source, measurement mode SCI, measurement diameter / illumination diameter = φ 8 mm / φ 11 mm, white background.

[0124] 〔Measurement of light transmittance〕 For light transmittance, each layer of the dental prosthesis produced in each of the examples and comparative examples was individually used, a single layer of zirconia sintered body was produced, and after processing in a manner to form a round plate having a diameter of 14 mm and a thickness of 1.2 mm (both sides #2000 polishing), using a spectrophotometer CM-3610A manufactured by Konica Minolta, Inc., measurement was performed using a D65 light source, and the L* value of the lightness (color space) in the L*a*b* color system (JIS Z 8781-4:2013) obtained was calculated as follows. The L* value obtained by measuring the sample with the background set to white was denoted as the 1st L* value, the L* value obtained by measuring the same sample with the background set to black was denoted as the 2nd L* value, and the value obtained by subtracting the 2nd L* value from the 1st L* value (ΔL*) was set as the value indicating the light transmittance.

[0125] [Table 1] 1) indicates the content of each pigment with respect to the total amount of zirconia and all pigments. However, Comparative Example 1 is a commercially available disc, and the content of the pigment was not measured.

[0126] The results of evaluation by visual observation were that the dental prosthesis of Examples 1 and 2 had a shape similar to the layer structure of a natural tooth, and thus a front tooth frame having excellent aesthetic properties and close to a natural tooth could be produced compared to Comparative Example 1 having a laminated structure of four layers in parallel.

[0127] Industrial Applicability The ground blank of the present application can be used as a dental prosthesis having high aesthetic properties.

[0128] Explanation of Reference Signs 1 Enamel layer 2 Intermediate layer 3 Main body layer 4 Imaginary first cut layer 5 Imaginary second cut layer 6 Shoulder

Claims

1. A mill blank, which is a mill blank for dental use, having a mill blank portion with a laminated structure of 2 or more layers, In the laminated structure, a body layer (3) is present on the inner side of the enamel layer (1), the body layer (3) has a bottom surface and a side surface, and the side surface is a shape having a portion perpendicular to the bottom surface, The mill blank portion has 1 or more intermediate layers (2) between the enamel layer (1) and the body layer (3), At least one cross section of the intermediate layer (2) perpendicular to the bottom surface is a shape of a canister, The light transmittance ΔL* of the body layer (3) < the light transmittance ΔL* of the intermediate layer (2) < the light transmittance ΔL* of the enamel layer (1) is satisfied, The light transmittance ΔL* is a value obtained by individually using the zirconia powder of each layer, producing a single layer of zirconia sintered body, machining in a manner to form a round plate of 14 mm in diameter and 1.2 mm in thickness, measuring using a spectrophotometer CM-3610A manufactured by Konica Minolta, Inc. with a D65 light source, using the L* value of the lightness in the L*a*b* color system according to JIS Z 8781-4:2013, and calculating as follows: the L* value obtained by measuring with the background of the sample set to white is referred to as the 1st L* value, the L* value obtained by measuring with the background of the sample set to black is referred to as the 2nd L* value, and the value obtained by subtracting the 2nd L* value from the 1st L* value, i.e., ΔL*, is set as the value indicating the light transmittance, Further, the L* value in the L*a*b* color system satisfies the relationship of the L* value of the enamel layer (1) < the L* value of the body layer (3) < the L* value of the intermediate layer (2).

2. The mill blank of claim 1, wherein, The mill blank portion is a quadrangular prism shape.

3. The grinding blank according to claim 1 or 2, wherein, At least one cross section of the body layer (3) parallel to the bottom surface is a shape having a profile obtained by combining at least 2 selected from a circular arc, an elliptical arc, a parabola, and a catenary.

4. The mill blank according to any one of claims 1 to 3, wherein, At least one cross section of the body layer (3) perpendicular to the bottom surface is a shape of a canister.

5. The mill blank according to any one of claims 1 to 3, wherein, At least one cross section of the body layer (3) perpendicular to the bottom surface is a convex shape.

6. The mill blank according to any one of claims 1 to 5, wherein, The intermediate layer (2) has a bottom surface and a side surface, and the side surface is a shape having a portion perpendicular to the bottom surface.

7. The mill blank according to any one of claims 1 to 6, wherein, At least one cross section of the intermediate layer (2) parallel to the bottom surface is a cross-sectional shape obtained by combining at least 2 selected from a circular arc, an elliptical arc, a parabola, and a catenary.

8. The mill blank according to claim 6 or 7, wherein At least one cross section of the intermediate layer (2) perpendicular to the bottom surface is a shape of a canister.

9. The mill blank according to claim 6 or 7, wherein, At least one cross section of the intermediate layer (2) perpendicular to the bottom surface is a convex shape.

10. The mill blank according to any one of claims 1 to 9, wherein, The hue and / or the light transmittance of each layer adjacent to each other in the laminated structure are different from each other.

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