JP7333998B2 - Manufacturing method for blank for dental processing - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a dental processing blank for cutting and processing a dental prosthesis such as a crown, a partial crown, or a denture.

Dental prostheses used in dental treatment are generally formed by casting metal materials such as gold, silver, titanium, and palladium alloys, or by processing non-metal materials such as ceramics and hybrid resins. Alternatively, the core portion is made of a metallic material, and the surface layer portion such as the veneer portion is made of a non-metallic material. A hybrid resin (hereinafter sometimes abbreviated as "HR") means a composite material in which an inorganic filler (hereinafter also referred to as an "inorganic filler") is dispersed at high density in a resin matrix. Usually, it is obtained by polymerizing and curing a paste-like polymerizable and curable composition containing a polymerizable monomer, an inorganic filler and a polymerization initiator by pressurizing and heating.

Dental prostheses made entirely of non-metallic materials have the advantage of being free from metal allergies and are highly aesthetically pleasing. has become easier, and the demand is growing rapidly. For example, as disclosed in Patent Document 1, using a CAD/CAM device based on computer aided design (CAD: computer aided design) and computer aided manufacturing (CAM: computer aided manufacturing) technology from intraoral photographed images CAD/CAM systems for cutting dental blanks made of non-metallic materials to form dental prostheses have become popular. Here, the dental processing blank means an object to be cut (also called a mill blank) that can be attached to a cutting machine in a CAD/CAM system. a retainer for attachment to the machine. As the part to be cut, a (solid) block formed in the shape of a rectangular parallelepiped or a cylinder, or a (solid) disk formed in the shape of a plate or disc is generally known, and the part to be cut is a hybrid. Also known are those made of resin.

By the way, in dental crown restorative treatment, dental prostheses are sometimes required to have aesthetic properties such as color tone and appearance that are equal to or close to those of natural tissue. In order to ensure such aesthetics, for example, in many cases, it is not sufficient to manufacture from dental processing blanks of a single color tone, and manufacturing from dental processing blanks of different color tones is performed. there is To this end, dental blanks are used which have a multi-layer structure in which multiple layers of different colors are integrated.

For example, in Patent Document 2, it has excellent aesthetic effect, excellent mechanical strength without special processing such as coating treatment, can be used stably for a long period of time, is excellent in workability such as cutting and grinding, and has foaming properties. does not remain inside the block, and when a block is formed by superimposing a plurality of resin layers, the resin layers are firmly bonded without a pressurization process, and the color tone is close to natural and further improved. The following method has been proposed as a method capable of forming a dental prosthesis processing block having an aesthetic effect and a gradation in color tone. That is, a method for manufacturing a dental prosthesis processing block composed of an integral combination of a plurality of block members, comprising the steps of preparing a mold having an inner surface shape corresponding to the outer surface shape of the block; a step of filling a composite resin material containing a resin and an inorganic filler dispersed therein capable of forming the block by curing; and a step of curing the composite resin material after the agitation treatment by polymerization, filling the composite resin material in a plurality of times, and after each filling step, the rotation agitation treatment A method for manufacturing a block for processing a dental prosthesis has been proposed, in which the steps and the curing step are sequentially performed, and after the final curing step, the resulting cured product is further polymerized and cured to form the combined body. there is

In addition, Patent Document 3 describes a resin layer for dentin restoration and a resin layer for enamel restoration as a cutting block for dental CAD/CAM that is said to have excellent versatility and productivity and to reproduce the appearance of natural teeth. A dental CAD/CAM resin block in which at least the dentin restoration resin layer contains light diffusing particles, and the contrast ratio and the diffusion ratio are each adjusted within a specific range. Cutting blocks for CAD/CAM have been proposed. In addition, in Patent Document 3, a composition to be a resin layer for dentin restoration is filled into a mold to a predetermined height so as not to involve air bubbles, the upper surface is smoothed, and after heat and pressure polymerization, It is described that the above block was obtained by additionally filling a composition for a resin layer for repairing enamel into the mold, smoothing the upper surface, and polymerizing under heat and pressure.

In addition, US Pat. No. 5,300,002 discloses a method of manufacturing a laminated mill blank that is both aesthetically pleasing and mechanically strong. In this mill blank manufacturing method, for example, a plurality of pasty polymerizable and curable compositions are sequentially filled into a fluororesin container having a predetermined bottom area and height and serving as a mold so that each has a predetermined thickness. to obtain a laminate before polymerization, and then polymerize the laminate.

Japanese Patent Application Publication No. 2016-535610 WO 2009/154301 pamphlet JP 2017-213394 A JP 2017-113224 A

Patent Documents 2 and 3 disclose a method for manufacturing a multi-layered dental processing blank (a dental prosthesis processing block or a dental CAD/CAM cutting block) in which a curable composition as a raw material for a base layer is placed in a mold. After filling and polymerizing and curing (cured body) to form a base layer, a paste-like curable composition that is a raw material for the upper layer is additionally filled into the mold and polymerized and cured (cured body) to form the upper layer. is formed, and it is necessary to carry out a plurality of polymerization and curing treatments that require heating under pressure and irradiation with light. In addition, since the layers of the pasty polymerizable composition, which are the raw materials of two adjacent layers, do not mix microscopically at the interface, the strength may be lowered at the interface after polymerization.

On the other hand, in the method described in Patent Document 4, a laminate (before polymerization) of a paste-like curable composition as a raw material for each layer (hereinafter also referred to as a "paste laminate") is obtained, and then polymerized. Therefore, only one polymerization and curing treatment is required, and there is an advantage that the interfacial strength between the layers can be increased.

However, especially when the ratio of the mass of the inorganic filler to the total mass of the paste-like curable composition (hereinafter also referred to as "inorganic filler filling rate") is high, filling and lamination in the process of obtaining a paste laminate Not only is there a risk that the boundary between layers will be disturbed during this, resulting in a product with a disturbed interface between each layer, but also filling spots will occur and shape defects will occur, and voids will be present in the resulting blank. As a result, there is a risk that the strength will be reduced and that chipping will easily occur during cutting.

Therefore, the present invention provides a method for producing a dental processing blank having a portion to be cut made of a hybrid resin laminate (HR laminate) in which a plurality of layers made of hybrid resin (HR) are laminated, wherein the hybrid It is possible to reduce the number of times the paste-like curable composition that is the raw material of the resin is polymerized and cured, and even when using the paste-like curable composition with a high inorganic filler filling rate, the hybrid resin that becomes the cut part A first object of the present invention is to provide a method for laminating each layer neatly and reliably so that there is no disorder at the interface between the layers and no decrease in strength or chipping occurs.

On the other hand, when the HR laminate is used as the cut portion, the number of HR layers to be laminated is small and the number of HR layers to be laminated is small, even if each layer is neatly and surely laminated so as not to cause a decrease in strength or chipping. If the color tones of adjacent layers are significantly different, the boundary between the two layers becomes rather conspicuous and unnatural. In order to eliminate such unnaturalness, as shown in Patent Document 2, the number of layers is increased and gradation is applied, or as shown in Patent Document 3, light diffusion is provided and transparency (contrast It is necessary to take measures such as controlling the angle dependence of transmitted light intensity (diffusion ratio) and the like.

For example, it has two layers, an HR layer (for example, a resin layer for dentin restoration) that reproduces the color tone near the cervical portion of a natural tooth and an HR layer (for example, a resin layer for enamel restoration) that reproduces the color tone near the incisal portion. In the case of the HR laminate, when a neutral color layer is provided between the two layers due to the size of the tooth, the thickness of that layer is naturally limited. In the case of forming a neutral color layer, it is necessary to make the thickness of each layer of the corresponding paste-like polymerizable composition (raw material of HR) extremely thin, which is not only complicated but also reduces the production yield. is concerned. In the latter method, since an intermediate layer is not provided, such concerns do not arise. It has been found that if the difference in transparency or light diffusivity between both layers becomes too large, the lamination interface may become conspicuous depending on the degree of incidence of light.

Therefore, the present invention provides an HR laminate in which each layer is neatly and surely laminated, and although it has a layer composed of two types of HR having relatively large color tones as main layers, it is simple and cost-effective. is also an advantageous method, in other words, it does not adversely affect the degree of light incidence without increasing the number of layers interposed between the two layers or finely controlling the transparency of each layer or the angular dependence of the transmitted light intensity. It is a second object of the present invention to provide a dental work blank having a cut portion made of an HR laminate in which the boundaries between layers are naturally visible due to the gradation effect which is difficult to receive.

The present invention is intended to solve the above problems, and a first aspect of the present invention is a multilayer lamination of layers composed of a paste-like polymerizable composition containing a polymerizable monomer, an inorganic filler, and a polymerization initiator. In a method for manufacturing a dental processing blank having a portion to be cut made of a hardened paste laminate,
A: A formwork kit consisting of a first formwork unit and a second formwork unit, each consisting of a cylindrical body with both ends open and a columnar cavity formed therein, wherein these two formwork units are By connecting the cylindrical bodies in the axial direction, a connecting form having a connecting cylindrical body and a connecting columnar cavity formed by connecting the cylindrical bodies and the columnar cavities of both formwork units is formed. preparing the formwork kit to obtain;
B: A first paste-like polymerizable composition and a second paste-like polymerizable composition having different color tones, and one or two types of intermediate-colored pastes having intermediate colors of the color tones of these paste-like polymerizable and hardenable compositions. preparing a polymerizable curable composition;
C: The first mold unit is filled with the first pasty polymerizable composition and one of the one or two intermediate color paste polymerizable compositions to have a uniform thickness. Paste filling filled in the first mold unit in a state in which the first paste-like polymerizable composition layer and the one kind of intermediate color paste-like polymerizable composition layer having a uniform thickness are laminated. While producing the first formwork unit,
When there are two types of the second paste-like polymerizable and curable composition in the second mold unit, or the second paste-like polymerizable and curable composition and the one or two neutral color paste-like polymerizable and curable compositions The paste-filled second mold unit in which the second mold unit is filled with the second paste-like polymerizable composition by filling with the other one in the second mold unit, or the second mold unit having a uniform thickness Paste filled in the second formwork unit in a state in which two paste-like polymerizable composition layers and the other neutral color paste-like polymerizable composition layer having a uniform thickness are laminated. making a filled second formwork unit;
D: The paste-filled first mold unit and the paste-filled second mold unit obtained in the above steps are divided into the first paste polymerizable composition layer and the second paste polymerizable composition layer. are connected so as to be laminated via the one or two intermediate color paste-like polymerizable composition layers to form the connecting form, and in the connecting columnar cavity, each paste filling mold A step of obtaining a paste laminate filling connection formwork by joining the pasty polymerizable composition filled in the frame unit to form a paste laminate;
E: A curing step of curing the paste laminate inside the connecting columnar cavity to form a cured body;
including
In the step C, the thicknesses of the layers of the first paste polymerizable composition and the one neutral color paste polymerizable composition filled in the paste-filled first mold unit are T1 and _T1 , respectively. Let T _M1 be the thickness of the layer of the second paste-like polymerizable composition and the other one kind of intermediate-color paste-like polymerizable composition filled in the paste-filled second mold unit, respectively. ₂ and T _M2 , the following formulas (1) to (3)
T _M1 /(T ₁ +T _M1 )=0 to 0.30 (1)
T _M2 /(T ₂ +T _M2 )=0 to 0.30 (2)
(T _M1 +T _M2 )/(T ₁ +T _M1 +T ₂ +T _M2 )=0.01 to 0.30 (3)
A method of manufacturing a blank for dental processing, characterized in that all the relationships shown in are satisfied.

In the method for manufacturing a dental processing blank of the first embodiment (hereinafter also referred to as "the manufacturing method of the present invention"), in the step C, each of the first mold unit and the second mold unit is and having a flat contact surface that contacts with the paste polymerizable composition filled in the columnar cavity, and the filled paste polymerizable composition is passed through the supply side opening, which is the opening on the other side. A push-out plate for pushing out is inserted into the columnar cavity so as to be movable back and forth and detachable to close the closing side opening which is one end opening of each formwork unit, and then the first mold is inserted into the columnar cavity. In the frame unit, the contact surface is in contact with the first paste polymerizable composition, and in the second mold unit, the contact surface is in contact with the second paste polymerizable composition. By densely filling the pasty polymerizable and curable composition, the closing side opening, which is one side opening, is closed with the extrusion plate, and the supply side opening, which is the other side opening, is planar or substantially preparing the paste-filled first mold unit and the paste-filled second mold unit, each having a planar paste joint surface formed on the surface;
The step D is
Da1: For at least one of the paste-filled first mold unit and the paste-filled second mold unit, the extrusion plate is moved toward the supply side opening to extrude the pasty polymerizable and curable composition, and the a step of projecting a portion of the paste-like polymerizable composition from the supply side opening to form a convex surface on the paste joint surface; and Da2: after the step, the paste of the paste-filled first mold unit. Both paste-filled formwork units are connected so that the joint surface and the paste-joint surface of the paste-filled second formwork unit overlap to form the connection formwork, and both pastes are placed in the connection columnar cavity. The pasty polymerizable composition filled in a filling mold unit is joined to form the paste laminate, and the paste in which the openings at both ends of the connecting mold are substantially closed with an extrusion plate. obtaining a laminate filled and connected formwork;
(This preferred method is hereinafter also referred to as the “convex curved surface joining method of the present invention”).

A second embodiment of the present invention is a hybrid resin in which HR layers are laminated, each having a uniform thickness and having three or four layers of light diffusing hybrid resins (HR) having different color tones. (HR) A dental processing blank having a portion to be cut made of a laminate,
The HR layers at one end and the other end of the HR laminate are the first HR layer and the second HR layer, respectively, and when there is one HR layer interposed between the HR layers at both ends, the HR layer is the first intermediate HR layer, and when there are two HR layers interposed between the HR layers at both ends, the first HR layer side is the first intermediate HR layer, and the second HR layer side is the second intermediate HR layer. when
The first intermediate HR layer and the second intermediate HR layer have a color tone intermediate between the color tone of the first HR layer and the color tone of the second HR layer. The color tone of the second intermediate HR layer has a color tone closer to the color tone of the second HR layer than the color tone of the first intermediate HR layer,
The thickness of each layer of the HR laminate is defined as the thickness of the first HR layer: _T'1 , the thickness of the second HR layer: _T'2 , and the thickness of the first intermediate HR layer: _T'M1. , the thickness of the second intermediate HR zinc layer: _T'M2 , and when the total thickness ( _T'1 + _T'M1 + _T'2 + _T'M2 ) is represented by T', the following formula (1') and (2')
( _T'M1 + _T'M2 )/T' = 0.01 to 0.30 (1')
_T'1 / _T'2 = 0.8 to 1.2 (2')
The blank for dental processing satisfies the relationship shown in .

In the dental processing blank of the second embodiment (hereinafter also referred to as "the dental processing blank of the present invention"), the first HR layer, the second HR layer, the first intermediate HR layer and the second intermediate The following formula, which is an index of the transparency of the HR constituting each layer of the HR layer: Contrast ratio = Yb/Yw
(Wherein, Y means the Y value obtained by spectral reflectance measurement using a spectrophotometer for a sample with a thickness of 0.3 mm ± 0.01 mm, and Yb and Yw are the background color black and the background color, respectively. Represents the above Y value measured for fair skin.)
All the contrast ratios defined by are in the range of 0.20 to 0.30, and the difference is 0.1 or less in all layers,
ΔE ^* ={(ΔL ^* ) ² +(Δa ^* ) ² +(Δb ^* ) ² , which is an index of the difference between the color tone of the HR that constitutes the first HR layer and the color tone of the HR that constitutes the second HR layer. } ^1/2
= {(L1 ^* -L2 ^* ) ²⁺ (a1 ^* -a2 ^* ) ²⁺ (b1 ^* -b2 ^* ) ² } ^1/2
(Wherein, L ^* , a ^* and b ^* are L ^* , a ^* and b obtained by spectral reflectance measurement with a white background using a spectrophotometer for a sample with a thickness of 1.0 ± 0.1 mm ^* , and L1 ^* , a1 ^* and b1 ^* and L2 ^* , a2 ^* and b2 ^* are L ^* and a of HR constituting the first HR layer and HR constituting the second HR layer, respectively. ^* and b ^* values.)
The color difference defined by: ΔE ^* is preferably in the range of 1-6.

In the manufacturing method of the present invention, the hybrid resin layered body to be cut is obtained by polymerizing and curing a paste layered body in which a plurality of layers made of a paste polymerizable composition are laminated, so that the number of times of polymerization and curing is reduced. (usually once). In addition, a formwork kit consisting of a plurality of formwork units, which can be connected to form a connection formwork, is used to prepare a pasty polymerizable and curable composition (hereinafter sometimes referred to as "fluid paste". ) is stacked in a state filled in the formwork unit, so even when a fluid paste with a high inorganic filler filling rate and low fluidity is used, shape defects are unlikely to occur, and each layer Defects such as turbulence and voids are less likely to occur at the interface between the two. Moreover, the fluid paste to be filled in the mold unit is not limited to one type, and even when two types of fluid paste are used, two types of fluid paste can be used without causing defects or disturbances at the lamination interface. It can be filled in the formwork unit so that the layers consisting of are stacked. For this reason, according to the method of the present invention, a layer composed of two types of HR with relatively large color tones is provided as the main layer, and a thin HR intermediate layer is neatly formed between the two layers (defects and disturbances are generated at the lamination interface). without).

Further, in the dental processing blank of the present invention, the HR laminate constituting the portion to be cut has, as main layers, layers composed of two types of HR having relatively large differences in color tone, and the number of layers interposed between the two layers is In spite of the small number of layers, the gradation effect, which is not easily affected by the degree of incidence of light, has the effect of making the boundary between layers look natural. Further, in the dental processing blank of the present invention, in the production method of the present invention, the fluid paste used is substantially different only in color tone without finely controlling the constituent components and composition for each layer. Therefore, it can be easily manufactured, and it can be said that the blank for dental processing is extremely advantageous from the viewpoint of the cost and labor required for manufacturing.

FIG. 2 is a schematic perspective view showing a state in which a blank holding pin for cutting is joined to a dental processing blank having a three-layer structure; 1 is a perspective view showing an outline of a dental prosthesis for a back tooth processed by cutting a dental processing blank; FIG. FIG. 4 is a diagram illustrating a lamination step in a method for manufacturing a dental processing blank having a three-layer structure according to an embodiment of the present invention; Here, FIG. 3A is a diagram showing an example of the first step of the lamination process, FIG. 3B is a diagram showing an example of the second step of the lamination process, and FIG. is a diagram showing an example of the third step of the stacking process, and FIG. 3D is a diagram showing an example of the fourth step of the stacking process. 1 is a perspective view of a mold unit for molding a dental blank; FIG. 1 is a perspective view showing an example of a filling tool used in a filling step in a method for manufacturing a dental processing blank having a three-layer structure according to an embodiment of the present invention, and showing a state before filling with fluid paste. FIG. FIG. 4 is a plan view showing a state in which a filling tool is used to fill fluid paste. FIG. 4 is a plan view showing a state in the middle of removing the formwork unit filled with the fluid paste together with the holding plate of the formwork unit. FIG. 4 is a perspective view showing a state in which the formwork unit filled with the fluid paste is detached together with the holding plate of the formwork unit. FIG. 4 is a schematic cross-sectional view of a filling tool for explaining a state of filling a mold unit with a fluid paste. Here, FIG. 9A is a diagram showing an example of a state in which the mold unit is filled with the fluid paste, and FIG. 9B is a diagram showing another state in which the mold unit is filled with the fluid paste. FIG. 4 is a diagram showing an example; 1 is a perspective view showing an example of a lamination device used in a lamination step when manufacturing a dental processing blank comprising three layers by a method for manufacturing a dental processing blank having a three-layer structure according to an embodiment of the present invention; FIG. FIG. 10 is a view showing a state in which the lowermost layer of the formwork units filled with the adhesive paste is arranged in the lamination device. FIG. 4 is a perspective view showing a state in which the filled fluid paste is protruding from the formwork unit arranged in the stacking device. FIG. 4 is a perspective view showing formwork units stacked by a stacking device; FIG. 5 is a perspective view showing and explaining an example of a formwork unit holder for holding the laminated formwork units when the laminated formwork units are subjected to a curing step.

1. Outline of the production method of the present embodiment In the production method of the present embodiment, when obtaining a hybrid resin laminate (HR laminate) that serves as a cut portion of a blank for dental processing, the number of times of polymerization and curing treatment is small, preferably once. In order to obtain the HR laminate, a paste laminate obtained by laminating a plurality of layers of a paste polymerizable composition containing a polymerizable monomer, an inorganic filler, and a polymerization initiator is polymerized and cured. In addition, the following steps A to D are performed before step E (curing step) in order to prevent shape defects from occurring in the obtained HR laminate, and to make it difficult for defects such as disturbances and voids to occur at the interfaces of each layer. I do.

Step A: A formwork kit comprising a first formwork unit and a second formwork unit, each of which is a cylindrical body with both ends open and a columnar cavity formed therein, wherein these two formwork units are connected in the axial direction of the cylindrical body to form a connecting form having a connecting cylindrical body and a connecting columnar cavity formed by connecting the cylindrical bodies and the columnar cavities of both formwork units, respectively. Prepare the formwork kit as described above.
Step B: A first paste-like polymerizable composition and a second paste-like polymerizable composition having different color tones, and one or two types of neutral-colored pastes having intermediate colors of the color tones of these paste-like polymerizable and hardenable compositions. A polymerizable curable composition is provided.
C: The first mold unit is filled with the first paste polymerizable composition and one of the one or two neutral color paste polymerizable compositions to form a first mold unit having a uniform thickness. 1 paste-like polymerizable composition layer and the above-mentioned intermediate color paste-like polymerizable composition layer having a uniform thickness are laminated and filled in the first mold unit. Along with making a formwork unit,
The second mold unit contains a second paste polymerizable composition, or when there are two types of the second paste polymerizable composition and the neutral color paste polymerizable composition, the other one is added to the second mold unit. A paste-filled second mold unit in which the second mold unit is filled with the second paste polymerizable composition, or a second paste polymerizable composition layer having a uniform thickness; A paste-filled second mold unit is produced in which the second mold unit is filled with the above-mentioned other neutral color pasty polymerizable composition layer having a uniform thickness and the second mold unit in a laminated state.
Step D: The paste-filled first mold unit and the paste-filled second mold unit obtained in the above step are combined with the first paste polymerizable composition layer and the second paste polymerizable composition layer, Paste-like polymerization filled into each paste-filled formwork unit in the connecting columnar cavity part, connected so as to be laminated via the intermediate-color paste-like polymerizable curable composition layer to form the above-mentioned connection formwork A paste laminate-filled connecting mold is obtained by joining the curable composition to form a paste laminate.

Further, in the production method of the present embodiment, in the step C, the first paste-like polymerizable composition layer having a uniform thickness and the one neutral-color paste-like polymerizable composition layer having a uniform thickness When filled in the first mold unit in a state in which the layers are laminated, and the second pasty polymerizable composition layer having a uniform thickness and the other one intermediate color having a uniform thickness In order to prevent defects and disturbances at the lamination interface when filling the second mold unit in a state in which the paste polymerizable composition layer is laminated, and the first paste polymerizable composition In order to use the material layer and the second paste-like polymerizable composition layer as the main layers of the paste laminate, all the relationships represented by the following formulas (1) to (3) are satisfied.

T _M1 /(T ₁ +T _M1 )=0 to 0.30 (1)
T _M2 /(T ₂ +T _M2 )=0 to 0.30 (2)
(T _M1 +T _M2 )/(T ₁ +T _M1 +T ₂ +T _M2 )=0.01 to 0.30 (3)
In the above formula, T ₁ and T _M1 are respectively the thickness of the first paste-like polymerizable composition in the paste-filled first mold unit and the layer of one type of intermediate color paste-like polymerizable composition. and T ₂ and T _M2 are respectively the thickness of the second pasty polymerizable composition in the paste-filled second mold unit and the thickness of the other one neutral paste polymerizable composition It means the thickness of a layer of something. Further, T _M1 /(T ₁ +T _M1 ) is preferably more than 0 and 0.30 or less, more preferably 0.05 to 0.25, and T _M2 /(T ₂ +T _M2 ) is 0 to 0 .25 and (T _M1 +T _M2 )/(T ₁ +T _M1 +T ₂ +T _M2 ) is preferably between 0.02 and 0.25.

2. Overview of the dental processing blank of the present embodiment The dental processing blank of the present embodiment is a hybrid resin (HR) having three or four layers of light diffusing properties each having a uniform thickness and different color tones. It has a cut part made of a hybrid resin (HR) laminate in which layers of are laminated. The HR layers at one end and the other end of the HR laminate are defined as a first HR layer and a second HR layer, respectively, and one or two HR layers interposed between the HR layers at both ends are defined as an intermediate HR layer. When combined, the intermediate HR layer has a tone intermediate between the tone of the first HR layer and the tone of the second HR layer. Furthermore, when there are two intermediate layers, when the first HR layer side is the first intermediate HR layer and the second HR layer side is the second intermediate HR layer, the color tone of the second HR layer is the same as that of the first intermediate HR layer. It has a tone closer to the hue of the second HR layer than the tone of the layer. By providing such an intermediate layer, it is possible to obtain a gradation effect that is less affected by the incidence of light. In addition, since each layer has the same moderate light diffusivity, one layer or two layers, and the layer thickness is easy to control and moderate thinness that does not adversely affect tooth restoration. Even if the thickness satisfies the conditions represented by the following formulas (1') and (2'), an excellent gradation effect can be obtained in which the boundary between layers is inconspicuous.

( _T'M1 + _T'M2 )/T' = 0.01 to 0.30 (1')
_T'1 / _T'2 = 0.8 to 1.2 (2')
In the above formula, _T'1 is the thickness of the first HR layer, _T'2 is the thickness of the second HR layer, _T'M1 is the thickness of the first intermediate HR layer, and _T'M2 is the thickness of the second HR layer. 2 denotes the thickness of the intermediate HR layer and T' denotes the total thickness ( _T'1 + _T'M1 + _T'2 + _T'M2 ), respectively. Further, it is preferable that ( _T'M1 + _T'M2 )/T'=0.02 to 0.25 _{and T'1} / _T'2 =0.9 to 1.1.

Hereinafter, a dental processing blank having a three-layer structure according to a preferred embodiment of the dental processing blank of the present embodiment, a method for manufacturing the dental processing blank, and a manufacturing apparatus used therefor will be described with reference to the drawings. In the dental processing blank 1 having a three-layer structure according to this embodiment, as shown in FIG. The portion to be cut consists of an HR laminate having a three-layer structure provided with a (first) intermediate HR layer 1c′ having (hereinafter also simply referred to as "first layer") 1a, second paste polymerizable composition layer (hereinafter also simply referred to as "second layer") 1b and (first) intermediate color paste polymerizable curable composition layer It corresponds to the cured body of the composition layer (hereinafter also simply referred to as "intermediate layer") 1c. A blank 1 for dental processing is formed by joining a holding pin 2 to a portion to be cut made of this HR laminate. It is fixed to a cutting device of a CAD/CAM system via this blank holding pin 2, and is cut into a dental prosthesis 10 as shown in FIG.

(Formwork unit and process A)
In the manufacturing method of the present embodiment, as the step A, a formwork kit consisting of a first formwork unit and a second formwork unit each comprising a tubular body having both ends opened and a columnar cavity formed therein. By connecting these two formwork units in the axial direction of the tubular body, the tubular body and the columnar hollow part of the two formwork units are respectively connected to form a joint tubular body and a joint columnar body. A formwork kit is provided which is capable of forming an interlocking formwork having a cavity. The formwork unit and formwork kit used here will be described with reference to FIGS.

FIG. 3 is a view for explaining the step D of joining the paste-filled first mold unit and the paste-filled second mold unit when manufacturing the dental processing blank 1 having a three-layer structure. The first layer 1a, the intermediate layer 1c and the second layer 1b are formed by the first formwork unit 3 and the second formwork unit 4, respectively. That is, each of the first mold unit 3 and the second mold unit 4 is filled with a fluid paste P of a different kind of dental curable composition.

In addition, when the total thickness (layer thickness) of the first layer 1a and the intermediate layer 1c and the thickness (layer thickness) of the second layer 1b are equal, the first mold unit 3 and the second mold unit 4 use the same formwork unit. Since the basic structures of these formwork units 3 and 4 are the same even if the wall thicknesses are different, the first formwork unit 3 will be explained below with reference to FIG.

As shown in FIG. 4, the first formwork unit 3 is composed of a cylindrical body having a columnar cavity, and openings at both ends of this cylindrical body are a closing side opening 3b and a supply side opening 3c. Further, the closing-side opening 3b accommodates an ejector plate 3a having a flat contact surface which is slidable in the cavity of the first formwork unit 3 in the axial direction of the cylindrical body. In addition, as shown in FIG. 3(C), the closing side opening 4b of the second formwork unit 4 accommodates the ejector plate 4a. These ejector plates 3a and 4a are positioned at the closing side openings 3b and 4b in a state in which the mold units 3 and 4 are filled with the fluid paste P, and close the closing side openings 3b and 4b. As will be described later, fluid paste P is supplied from supply side openings 3c and 4c on the side opposite to the closing side openings 3b and 4b, and the formwork units 3 and 4 are filled with the paste.

Further, when the generatrices of the columnar cavities of the first formwork unit 3 and the second formwork unit 4 are aligned and connected, a connection columnar cavity is formed. That is, the first formwork unit 3 and the second formwork unit 4 constitute a formwork kit, and this formwork kit is prepared in the preparation process. In addition to the block shape shown in the drawing, it is possible to produce a blank of any shape by forming a formwork unit shape that matches the target blank shape.

In the figure, the columnar cavities of the first formwork unit 3 and the second formwork unit 4 are shown to have the same shape. Any columnar shape may be used as long as the connecting columnar cavities are sometimes formed. For example, one or both of the connecting columnar cavities may be cylindrical, or may be truncated quadrangular pyramids or truncated cones. A structure for fixing and positioning a blank holding pin, a structure for fixing to a cutting device, and a shape for providing other functionality can be provided on the inner surface of the columnar hollow portion.

(Relationship between the paste-like polymerizable composition and step B, and the relationship between the paste-like polymerizable composition and each HR layer in the blank for dental processing according to the present embodiment)
As described above, the HR laminate constituting the portion to be cut of the blank for dental processing includes a first paste polymerizable composition layer (first layer) 1a and a second paste polymerizable composition layer (second layer). Two layers) 1b and (first) neutral color pasty polymerizable composition layer (intermediate layer) 1c are cured. Here, the paste-like polymerizable composition (fluid paste) includes a polymerizable monomer, an inorganic filler, and a polymerization initiator, and is a paste-like composition obtained by kneading these components. be. As these raw materials, those used as raw materials for HR can be used without particular limitation. The filler filling rate of the fluid paste is preferably 60 to 99 wt%, more preferably 65 to 97 wt%, even more preferably 70 to 95 wt%. A filling rate of 60% or more reduces fluidity, but provides a dental blank having excellent physical properties as a dental prosthesis. Moreover, prior to manufacturing the blank 1 for dental processing, it is preferable to subject the fluid paste to a vacuum to deaerate and remove air bubbles.

Further, optional components may be added to the above in order to achieve the desired properties of the blank. Examples include polymerization inhibitors, chain transfer agents, fluorescent agents, ultraviolet absorbers, antioxidants, pigments, antibacterial agents, and X-ray contrast agents. can.

When the dental processing blank of the present embodiment is produced by the production method of the present embodiment, at least a portion of the inorganic filler, preferably the entire dental curable composition, is used to impart light diffusibility to the HR layer. , 30 to 90% by mass must be particles known to have a function of imparting light diffusion. As described in Patent Document 3, a resin matrix (cured polymerizable monomer component) having an average particle size of 1 to 50 μm, the particles themselves being transparent, and having a refractive index of HR at 25° C. Particles differing in refractive index by at least 0.01 are known to impart light diffusing properties to the HR. The inorganic filler having the function of imparting light diffusivity may be blended as it is, or may be blended in the form of an organic-inorganic composite filler. The organic-inorganic composite filler has an average particle diameter of 1 to 20 μm and a refractive index of nF, as described in JP-A No. 2002-138008, for example. The absolute value of nF-nM is 0.01 or more, where nM is the refractive index of the cured body (the portion that becomes the matrix in which the organic-inorganic composite filler is dispersed in the HR obtained by curing the fluid paste). An organic-inorganic composite filler that satisfies the requirements is used. Inorganic fillers and organic-inorganic composite fillers that have the function of imparting light diffusion have an average particle diameter larger than the wavelength of visible light (0.4 to 0.7 μm), so that light refraction and reflection occur effectively, and the matrix Because of the large difference in the refractive index of the hardened body, the light incident on the hardened body is more likely to be refracted and reflected at the interface between the composite filler and the matrix. By diffusing the light, the light diffusibility is enhanced, and the background color and the outline of the adjacent HR can be blurred.

In the manufacturing method of the present embodiment, in order to manufacture the dental processing blank having the three-layer structure, as the step B, a first paste-like polymerizable and curable composition (first fluid paste) having different color tones and a first 2 paste-like polymerizable and curable compositions (second fluid paste), and one type of neutral-colored paste-like polymerizable and curable composition (intermediate-color fluid paste) having an intermediate color tone of these paste-like polymerizable and curable compositions are prepared. However, the color tone can be adjusted at this time by adjusting the type and blending amount of coloring matter components such as pigments and dyes. The type of dye component to be used is not particularly limited. Specific examples include chromates such as yellow lead, zinc lead and barium yellow; ferrocyanides such as Prussian blue; sulfides such as silver vermillion, cadmium yellow, zinc sulfide, antimony white and cadmium red; barium sulfate and zinc sulfate. , Sulfate such as strontium sulfate; Oxides such as zinc oxide, titanium oxide, zirconium oxide, red iron oxide, iron black, and chromium oxide; Hydroxides such as aluminum hydroxide; silicates such as calcium silicate and ultramarine blue; Carbon Carbon such as black and graphite; nitroso pigments such as naphthol green B and naphthol green Y; nitro pigments such as naphthol S and lithol fast yellow 2G; Azo pigments; sparingly soluble azo pigments such as Risol Red, Lake Red C, Lake Red D; soluble azo pigments such as brilliant carmine 6B, permanent red F5R, pigment scarlet 3B, Bordeaux 10B; phthalocyanine blue, phthalocyanine green, sky phthalocyanine pigments such as 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 can be used alone or in combination.

The color tones of the first fluid paste and the second fluid paste may be different from each other. The color difference ΔE ^* , which is an index of the difference in color, is preferably in the range of 1.0 to 6.0, particularly in the range of 2.5 to 5.0. Here, the color difference ΔE ^* refers to L ^* , a*, and L ^* obtained by measuring the spectral reflectance of a sample having a thickness of 1.0±0.1 mm on the first HR and the second HR with a white background using a spectrophotometer. When the values of b ^* are L1 ^{*, a1*} and b1 ^* and L2 ^{* ,} a2 ^* and b2 ^* , respectively, they are values calculated by the following formula.

ΔE ^* = {(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² } ^1/2
= {(L1 ^* -L2 ^* ) ²⁺ (a1 ^* -a2 ^* ) ²⁺ (b1 ^* -b2 ^* ) ² } ^1/2

When the first HR of the dental processing blank of the present embodiment is on the incisal side, the preferred ranges of L1 ^{* ,} a1 ^* , and b1 ^* are exemplified as follows: L1 ^* is 60 to 90; 0, b1 ^* is 0 to 25, and the preferred range of L2 ^* , a2 ^* , b2 ^* of the color tone of the second HR on the cervical side is 50 to 80 for L2 ^* , and -3 for a2 ^* . .0 to 5.0, and b2 ^* is 5 to 30.0. In addition, the intermediate HR layer preferably has a color tone exhibited when a mixture of the first and second fluid pastes is mixed at a ratio ^of 1:3 to 3:1 and cured. The ranges of aM ^* and bM ^* are 52 to 88 for L ^* , -4.5 to 4.5 for a ^* , and 1 to 29 for b*.

When the values of L ^* , a ^* , b ^* of the first HR layer and the second HR layer to be used are known, the values of LM ^* , aM ^* , bM ^* suitable for the intermediate HR layer can be determined from those values. It is also possible to calculate the range as follows.

LM ^* = {(0.25 L1 ^* ) + (0.75 L2 ^* )}
~ {(0.75 L1 ^* ) + (0.25 L2 ^* )}
aM ^* ={(0.25*a1 ^* )+(0.75*a2 ^* )}
~{(0.75·a1 ^* )+(0.25·a2 ^* )}
bM ^* ={(0.25*b1 ^* )+(0.75*b2 ^* )}
˜{(0.75·b1 ^* )+(0.25·b2 ^* )}.

In addition, although related to the following contrast ratio, measurement using a spectrophotometer as a sample of a cured fluid paste with a thickness of 1.0 ± 0.1 mm is performed with a white background (background color: white) and a black background (background color: white). The difference between the lightness of the white background (L ^* w) and the lightness of the black background (L ^* b), which is obtained based on the lightness (L ^* ) obtained when each of the colors is black): ΔL ^* wb Then, the absolute value of the difference between ΔL*wb1 ^, which is ΔL ^* _wb in the first fluid paste, and ΔL ^* wb2, which is ΔL ^* _wb in the second fluid paste: |ΔL ^* _wb1 −ΔL ^* _wb2 | It is preferably 0 or less, more preferably 3.0 or less. Also, each of ΔL ^* _wb1 and ΔL ^* _wb2 is preferably 20 or less, more preferably 15 or less. By making a color tone that satisfies this relationship, conventionally, in order to reproduce the color tone from the incisal portion to the cervical portion of the tooth, the incisal portion is made thin and transparent, and the cervical portion is dark and opaque. It is possible to easily achieve the color tone of each layer that has been designed in advance with a simpler color tone configuration with less difference.

Furthermore, in order to obtain a natural gradation close to that of natural teeth despite the fact that the intermediate HR has an extremely small number of layers (one (or two)) and its thickness is relatively thin, the first HR layer, the second HR layer, and the (first) intermediate HR layer, the contrast ratio (Yb/Yw), which is an indicator of the transparency of the HR constituting each layer, is in the range of 0.20 to 0.30. (i.e., between the first HR layer and the intermediate HR layer, between the second HR layer and the intermediate HR layer, between the first HR layer and the second HR layer, between the first intermediate HR layer and the second intermediate HR layer , is preferably 0.1 or less, particularly 0.08 or less.

Contrast ratio = Yb/Yw
In the above formula, Y means the Y value obtained by spectral reflectance measurement using a spectrophotometer for a sample with a thickness of 0.3 mm ± 0.01 mm, and Yb and Yw are the background color black, respectively. and the above Y values measured on a white background.

The light diffusibility also affects the transparency of the cured HR, and in the case of the same color tone, the higher the light diffusivity, the lower the transparency. If the difference in contrast ratio between layers exceeds 0.1, the lamination interface may stand out depending on how light is incident.

The color difference ΔE ^* , ΔL ^* wb and the contrast ratio are determined by the type and amount of the organic-inorganic composite filler, the difference in refractive index between the polymerizable monomer after curing and the filler to be added, and the colorant such as pigment or dye. The composition of the polymerizable monomer, the organic-inorganic composite filler and the inorganic filler is the same or substantially the same or similar to the fluid paste that is the raw material of each layer. When a material is used, it can be easily controlled by adjusting the type and blending amount of the pigment component. For this reason, the first fluid paste, the second fluid paste, and the intermediate-color fluid paste should have the same or substantially the same composition of the polymerizable monomer, the organic-inorganic composite filler, and the inorganic filler. is preferred.

In addition, the intermediate-color fluid paste is a fluid paste having an intermediate color between the color tone of the first fluid paste and the color tone of the second fluid paste. A two-fluid paste can be easily prepared by mixing at a given mixing ratio, preferably between 1:3 and 3:1. When two kinds of intermediate color fluid pastes are used, the mixing ratio is changed so that the first intermediate color fluid paste is the first intermediate color fluid paste, and the second fluid paste is the second fluid paste. A medium color fluid paste may be used. The mixer used for mixing is not limited, and the method, size, etc. may be appropriately selected according to the properties of the paste so that uniform mixing can be achieved.

(filler)
5 to 9 schematically show a filling tool 5 used in the filling step of filling the mold units 3 and 4 with the fluid paste P. FIG. As shown in FIG. 3, the filling tool 5 comprises a holding plate 5a for holding the formwork units 3 and 4, a substantially U-shaped positioning block 5b for holding and positioning the holding plate 5a, and this positioning block 5b. and a filling platen 5c attached to the support surface 5c1.

Formwork unit housing portions 5d for housing the formwork units 3 and 4 are provided on the holding plate 5a. The mold unit accommodating portion 5d is formed by a through hole provided in the holding plate 5a.

In this embodiment, a structure in which a single formwork unit accommodation portion 5d is formed in the holding plate 5a is described, but the arrangement is not limited to such arrangement, and a plurality of formwork unit accommodation portions 5d are arranged on a straight line or on a circumference. may be aligned or arranged in a matrix. These arrangements can be appropriately designed according to the convenience of the filling device.

In addition, it is preferable to give the holding plate 5a and/or the formwork unit accommodating portion 5d a shape that takes into account the positioning and the convenience of the pre- and post-processes. you should design it.

On the other hand, the positioning block 5b is fixed on the support surface 5c1 of the filling platen 5c, as shown in FIG. The U-shaped inner portion of the positioning block 5b has a structure corresponding to the outer shape of the holding plate 5a, and the holding plate 5a is held in this U-shaped inner portion. In addition. The shape is not limited to the one shown in the drawing, and it is preferable to design the shape according to the shape of the holding plate 5a and the convenience of the device. .

For example, it is not limited to a U-shape, and a V-shape or a slide member such as a rail can also be used. Furthermore, it is also possible to form a plurality of formwork unit accommodating portions 5d on one holding plate 5a and shape the positioning block 5b to hold this holding plate 5a. Also, the positioning block 5b can be divided into a pair, and the mounting position of the positioning block 5b with respect to the filling plate 5c can be changed so that the holding state of the holding plate 5a can be adjusted. is also preferred.

The filling platen 5c is provided with a filling nozzle 5e formed by an opening provided in the support surface 5c1. As shown in FIGS. 5, 8 and 9A, a paste flow path 5c2 is formed toward the opening of this filling nozzle 5e. The shape of the flow path may be straight without a gradient, but as shown in FIG. It is preferable to take into account the properties and the desired blank shape, and design the blank appropriately so as not to cause any inconvenience. The opening of the filling nozzle 5e is not limited to the circular shape shown in the drawing, and both the opening area and shape can be appropriately set. For example, it may have the same shape as the opening of the formwork unit. Further, the filling nozzle 5e is arranged at a position corresponding to the through hole of the mold unit accommodating portion 5d of the holding plate 5a held by the positioning block 5b. For this reason, the fluid paste P of the curable composition extruded from an extrusion device (not shown) flows in the paste flow path 5c2, and the formwork unit 3, which is accommodated in the formwork unit accommodation section 5d from the filling nozzle 5e, 4.

As the fluid paste P is filled, the ejector plate 3a gradually moves upward in FIG. to close.

(Lamination device)
The formwork units 3 and 4 filled with the fluid paste P are aligned with the supply side openings 3c and 4c of the formwork units 3 and 4, and the filled fluid paste P is laminated. 10 to 12 schematically show a lamination device 6 used in the lamination step of laminating the fluid paste P of the curable composition filled in the first formwork units 3 and 4. FIG. It is preferable to appropriately design the structure of the stacking device in consideration of productivity and efficiency. As long as it is possible to stack the formwork units 3 and 4 while holding the positions thereof, the holding structure and arrangement using pins as shown in the figure are not limited. A plurality of them may be aligned on a straight line or on a circle, or more may be arranged in a matrix.

As shown in FIG. 10, the stacking device 6 has, as main components, a holding plate 6a on which the formwork units 3 and 4 are placed and held, and a push-up plate 6b overlapping the lower surface of the holding plate 6a. there is

A set of four positioning pins 6a1 is implanted in the holding plate 6a as a holding structure for each of the formwork units 3 and 4. They face each other and regulate the positions of the first formwork units 3 and 4 . 10 to 12, the positioning pins 6a1 positioned between the adjacent formwork units 3 and 4 are common to the holding structure of the adjacent formwork units 3 and 4. . The holding structure should not be limited to the structure shown in the figure, but should be a structure that can sufficiently hold according to the shape of the formwork units 3 and 4, such as a prism, flat plate, L-shaped angle, rail shape, etc., in addition to pins and cylinders. is preferred.

FIG. 10 shows a state in which the first formwork unit 3 is placed on the holding plate 6a, and the second formwork unit 4 is placed on the first formwork unit 3 as will be described later. be done. Alternatively, the second formwork unit 4 may be placed on the holding plate 6a and the first formwork unit 3 may be layered on the second formwork unit 4 .

In addition, in the central portion of the portion where the formwork units 3 and 4 are positioned and surrounded by the four decision pins 6a1 for positioning the formwork units 3 and 4, a through hole passing through the holding plate 6a is provided. 6a2 is provided.

A push-up rod 6b1 that can be inserted into and removed from the through-hole 6a2 is implanted in the push-up plate 6b. When the holding plate 6a and the push-up plate 6b are superimposed, the tip of the push-up rod 6b1 protrudes from the upper surface of the holding plate 6a by a sufficient degree to achieve the function described later. The size, shape, and arrangement of the through hole 6a2 and the push-up rod 6b1 can be appropriately designed in accordance with the intended shape of the blank, the arrangement of the holding plate 6a, and the like.

(Formwork unit holding device)
The first mold unit 3 and the second mold unit 4 are superimposed, and the filled fluid paste P is hardened to form a multi-layered dental blank 1 . When hardening these fluid pastes P, for example, a mold unit holding device 7 such as an example shown in FIG. 13 can be used. The formwork unit holding device 7 comprises a pair of holding frames 7a, 7b for receiving the formwork units 3, 4. As shown in FIG. The pair of holding frames 7a and 7b each have a cross section formed in a shape capable of holding the outer shape of the formwork unit, and are attached to the bottom plate 7c with their open sides opposed to each other. Formwork units 3 and 4 can be held in a stacked state inside the holding frames 7a and 7b. A pressing block 7d for pressing the formwork units 3 and 4 against the bottom plate 7c is detachably attached to the upper portion of the holding frames 7a and 7b. The pressing block 7d is fixed by a combination of a bolt 7e and a nut 7f or other structural fixing means. As shown in FIG. 13, in addition to fixing a set of formwork units 3 and 4 in an overlapping state, it is also possible to fix a plurality of sets so that they are aligned in a straight line or on a plane. It is sufficient to use a formwork unit holding device designed according to the shape of the blank and the fixing method.

Then, the formwork units 3 and 4 fixed by the formwork unit holding device 7 are subjected to the curing process.

(Process C)
In the manufacturing method of the present embodiment, in the step C, the first mold unit is filled with the first paste polymerizable composition and one of the one or two intermediate color paste polymerizable compositions. Then, a first mold frame is formed in a state in which the first paste-like polymerizable composition layer having a uniform thickness and the one kind of intermediate color paste-like polymerizable composition layer having a uniform thickness are laminated. A paste-filled first mold unit filled in the unit is produced, and a second paste-like polymerizable curable composition or a second paste-like polymerizable curable composition and the intermediate color paste are added to the second mold unit. A paste-filled second formwork unit in which the second formwork unit is filled with the second paste-like polymerizable and curable composition, or , a second mold frame in a state in which the second paste-like polymerizable composition layer having a uniform thickness and the other one kind of intermediate color paste-like polymerizable composition layer having a uniform thickness are laminated A paste-filled second mold unit filled in unit is produced.
That is, in step C, a "paste-filled first mold unit" and a "paste-filled second mold unit" are produced. Regardless, when making a "paste-filled first mold unit", the first mold unit is always filled with one type of neutral fluid paste. Then, in the "paste-filled first mold unit", the first paste-like polymerizable composition layer having a uniform thickness and the one kind of intermediate color paste-like polymerizable composition layer having a uniform thickness The layers are laminated.
On the other hand, regarding the "paste-filled second mold unit", (1) when only one type of intermediate-color fluid paste is used, the second mold unit is not filled with the intermediate-color fluid paste, and the "paste In the "filling second mold unit", the second paste-like polymerizable and curable composition is filled with a uniform thickness. Also, (2) when using two types of intermediate color fluid paste, the other one (other than the one type of intermediate color fluid paste filled in the first mold unit) is the second mold unit In the "paste-filled second mold unit", the second paste-like polymerizable curable composition layer having a uniform thickness and the other one kind of intermediate color paste-like polymerization having a uniform thickness The curable composition layer is laminated.

Process C can be performed as follows using the filling tool 5 described above. That is, first, the first formwork unit 3 is held in the formwork unit accommodating portion 5d of the holding plate 5a of the filling tool 5 . Next, as shown in FIG. 6, the holding plate 5a holding the first formwork unit 3 is placed inside the U-shape of the positioning block 5b and held by the positioning block 5b. In this state, the filling nozzle 5e arranged on the support surface 5c1 is positioned facing the cavity of the first mold unit 3. As shown in FIG. Then, the first fluid paste P is filled into the first formwork unit 3 through the paste flow path 5c2 by an injection device (not shown) connected below the filling platen 5c. As the filling amount of the fluid paste P increases, the ejector plate 3a positioned at the supply side opening 3c of the first mold unit 3 is gradually pushed up as shown in FIG. Move toward the opening 3b. When the ejector plate 3a is moved to the closing side opening 3b, a predetermined amount (layer thickness: T ₁ minute) of the first fluid paste P is applied to the first fluid paste P, leaving a space (layer thickness: T _M1 ) for filling the intermediate paste. 1 formwork unit 3 is filled. Next, the first formwork unit 3 filled with a predetermined amount of the first fluid paste P is once removed from the positioning block 5b together with the holding plate 5a. At this time, as shown in FIGS. 7 and 8, the holding plate 5a is moved so as to be pulled out from the open side of the U-shape while being guided by the inner wall surface of the U-shape of the positioning block 5b. moves so as to scrape the supporting surface 5c1 of the filling board 5c, thereby separating the holding plate 5a from the filling board 5c. By rubbing the support surface 5c1 with the holding plate 5a in this way, a planar paste bonding surface Pa is formed on the surface of the fluid paste P. As shown in FIG. After that, another filling tool equipped with an injection device (not shown) for injecting the intermediate paste {contrary to the filling tool shown in FIG. The opening area of the nozzle 5e is substantially the same as the area of the supply side opening 3c of the first formwork unit 3 (the same or slightly larger, but the size fits inside the outer circumference of the cylindrical body of the first formwork unit). It has a similar structure to filler 5 except that it is adapted to have a structure with shape and area sides. } is prepared, and the first flowable paste P sets the first mold unit 3 to this in a state in which the intermediate paste forms the same plane as the opening surface of the filling nozzle 5e. At this time, the extrusion plate 3a is slightly pushed in so that a part of the first fluid paste P slightly protrudes from the supply side opening 3c of the first mold unit 3 to form a convex curved surface. and gently hang down from above the positioning block 5b. By doing so, both paste layers can be joined within the first formwork unit 3 without disturbing the interface between the first fluid paste P and the intermediate paste. After the setting is completed, a predetermined amount of intermediate paste is filled in the same manner as described above, and the holding plate 5a of the first mold unit 3 after filling with the intermediate paste is removed from the filling platen 5c, thereby forming the intermediate paste. A paste-filled first mold unit with a planar paste-bonding surface Pa can be produced. At this time, the condition of T _M1 /(T ₁ +T _M1 )=0.01 to 0.30 is satisfied.

The method for producing the _paste -filled first formwork unit is not based on the above method. Prepare a sheet left still so as to configure, place the first mold unit 3 filled only with the first fluid paste P on it, and join the paste, and the surplus intermediate paste sheet may be removed. In addition, after holding the intermediate paste at a temperature at which the desired fluidity is obtained, it is joined to the first mold unit, or the filling rate is changed to achieve the desired fluidity. It is also possible to join. The fluidity of the paste may be appropriately adjusted depending on the mode.

For the second mold unit 4, the first fluid paste is added to the first mold unit 3, except that the filling amount of the second fluid paste P is set to an amount that is densely filled in the second mold unit 4. The second fluid paste P is filled in the same manner as in the case of filling, and a paste-filled second formwork unit having a planar paste joint surface Pa as shown in FIG. 3(C), for example, is produced.

Further, in the case of a four-layer structure having a second intermediate layer, the second fluid paste and the second intermediate paste may be filled according to the manufacturing method of the paste-filled first formwork unit.

(Process D)
In step D, the paste-filled first mold unit and the paste-filled second mold unit obtained in step C are combined into a first paste polymerizable composition layer and a second paste polymerizable composition layer. are connected so as to be laminated via the intermediate-color paste-like polymerizable composition layer to form the connecting form, and the paste filled in each paste filling form unit in the connecting columnar cavity part A paste laminate filling connection mold is obtained by bonding the polymerizable curable composition to form a paste laminate.

At this time, in the step D, for at least one of the paste-filled first mold unit and the paste-filled second mold unit, the extrusion plate is moved toward the supply side opening to extrude the paste polymerizable composition. , a step Da1 of projecting a part of the paste-like polymerizable composition from the supply side opening to make the paste joint surface a convex curved surface, and after the above step, the paste joint surface of the paste-filled first mold unit and the paste Both paste filling formwork units are connected so that the paste joint surface of the second filling formwork unit overlaps to form a connection formwork, and both paste filling formwork units are filled in the connection columnar cavity. a step Da2 of joining the pasty polymerizable curable composition to form a paste laminate to obtain a paste laminate filling connection form in which the openings at both ends of the connection form are substantially closed with extrusion plates; , it is preferable to adopt the convex surface method of the present embodiment.

When the convex curved surface method is adopted, the contact starts from the convex curved surface existing in the center of the paste contact surface, and the contact area gradually expands in the circumferential direction along the curved surface, so defects such as air bubbles are eliminated. Not only is it less likely to occur, but even if it does occur, it is pushed out in the circumferential direction, so it does not remain inside. In addition, even if air bubbles or the like remain near the periphery of the contact interface, they are discharged to the outside in the pressurization process, so the effect of preventing defects such as turbulence and voids at the interface of each layer can be extremely high.

The convex curved surface method can be suitably performed using a lamination apparatus shown in FIG. That is, as shown in FIG. 10, the first formwork unit 3 filled with the fluid paste is placed in a position regulated by the positioning pins 6a1 of the holding plate 6a of the stacking device 6, and the opening 3b on the closing side is positioned on the holding plate 6a. placed facing the upper surface of the In this embodiment, the first formwork unit 3 is arranged in the lowermost layer in the vertical direction. Next, as shown in FIG. 3A, the push-up rod 6b1 of the push-up plate 6b is inserted into the through hole 6a2 of the holding plate 6a to bring the push-up plate 6b closer to the holding plate 5a. When the push-up plate 6b overlaps the holding plate 6a, the tip of the push-up rod 6b1 protrudes from the upper surface of the holding plate 6a and pushes up the push-out plate 3a arranged in the first formwork unit 3. As a result, as shown in FIGS. 3B and 11, part of the intermediate fluid paste P filled in the first formwork unit 3 protrudes from the supply side opening 3c, forming a convex curved paste joint surface. Pa is formed. At this time, the amount of protrusion of the push-up rods 6b1 may be determined so that the intermediate fluid paste P protrudes to a position where it does not overflow or spill out of the first formwork unit 3.

As shown in FIG. 3C, the paste-filled first mold unit 3 in which the paste joint surface Pa of the fluid paste P protrudes is placed so that the supply-side opening 4c faces the supply-side opening 3c, and 2 nits of paste is applied. 4 is pressed against the paste-filled first formwork unit 3 . As a result, as shown in FIG. 3(D) and FIG. 12, both paste filling formwork units are superimposed to form a connection formwork, and each paste filling formwork unit is filled in the connection columnar cavity. The pasty polymerizable curable composition is joined to form a paste laminate, thereby obtaining a paste laminate filling connection mold.

At this time, when stacking the paste-filled second mold unit 4, the paste joint surface Pa of the fluid paste P protruding from the supply-side opening 3c of the paste-filled first mold unit 3 is replaced with the paste-filled second mold unit 4. Since the paste joint surface Pa of the fluid paste P in the unit 4 is pushed, the push-up rod 6b1 is previously lowered to a position where it does not protrude from the upper surface of the holding plate 6a. As a result, these fluid pastes P can be smoothly combined when the two paste filling formwork units are stacked. Moreover, since the paste joint surface Pa of the intermediate fluid paste P in the first mold unit 3 protrudes, the air gap between the paste joint surface Pa of the second fluid paste P in the second mold unit 4 and the paste joint surface Pa of the intermediate fluid paste P in the second mold unit 4 is reduced. contamination can be suppressed. Therefore, these fluid pastes can be reliably integrated. As a result, it is possible to form a paste laminate having a three-layer structure in which the interfaces inside the connecting molds are in order.

(Process E)
In the manufacturing method of the present embodiment, the paste laminate inside the connecting columnar cavity is cured to obtain a cured body. The curing can be suitably performed as follows. That is, the paste layered body filling connection formwork in which the first formwork unit 3 and the second formwork unit 4 are integrated is stacked and held by the formwork unit holding device 7 as illustrated in FIG. 13 . At this time, the formwork units 3 and 4 stacked and accommodated in the holding frames 7a and 7b are pressed and fixed by the pressing block 7d. By hardening the fluid paste P filled in the fixed formwork units 3 and 4, these fluid pastes P are integrated and hardened to become a hardened body, and a three-layer dental structure having different color tones is obtained. A working blank 1 is shaped. As a curing method, a known method such as a method of polymerizing and curing with energy such as heat or light can be used for the hybrid resin. A ceramic composition such as glass or zirconia can be hardened into a lump by sintering. Known sintering conditions may be used according to the type of composition.

After that, the cured three-layer fluid paste P is taken out from the formwork units 3 and 4, and if necessary, burrs and the like are removed, and polishing treatment for smoothing the surface, surface smoothing, printing, heat treatment, etc. are performed. A post-treatment is performed to produce a cut portion composed of the HR laminate having a three-layer structure.

Then, if necessary, as shown in FIG. 1, a blank holding pin 2 is adhered to the manufactured part to be cut with an adhesive or the like, and a dental prosthesis 10 as shown in FIG. 2 is cut. It becomes the product of the blank 1 for dental processing for. The blank holding pin is not particularly limited as long as it has a shape that can fix the blank to the cutting machine. Materials such as stainless steel, brass, and aluminum are used for the blank holding pin. The method of fixing the blank holding pin to the resin material for dental cutting is not based on the above-mentioned adhesion, but may be a method such as fitting or screwing, and the above-mentioned adhesion method is not particularly limited. , silicone-based, acrylic-based, and other commercially available adhesives can be used. The adhesive can be appropriately selected according to the manufacturing process, regardless of whether it is one-component curing or two-component or more mixed curing. In addition, the higher the compressive shear bond strength (JIS K 6852-1994) after bonding the retaining pin, the lower the possibility that the retaining pin will come off during processing of the dental prosthesis, but the force that the block receives from the processing machine will decrease. is about 300 N, so if it is set to 500 N or more, it is possible to work without falling off. Existing general knowledge can be used as a method for increasing the adhesive force, and it can be enhanced by roughening the surface, increasing the surface area, and providing a structure such as a groove for holding the adhesive. It is possible as appropriate.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.

Compounds used as raw materials for the paste-like polymerizable composition and their abbreviations are shown below.

[Polymerizable monomer]
· A-1: triethylene glycol dimethacrylate · A-2: 1,6-bis(methacrylethyloxycarbonylamino)trimethylhexane.

[Inorganic filler]
B-1: Spherical silica zirconia with an average particle diameter of 0.2 μm and a refractive index of 1.54 (surface-treated with γ-methacryloyloxypropyltrimethoxysilane)
B-2: Aggregated silica having an average particle size of 0.015 μm and a refractive index of 1.46.

[Organic-inorganic composite filler]
CF-1: average particle size of 12 μm, refractive index of 1.52, inorganic component is silica zirconia (surface treated with γ-methacryloyloxypropyltrimethoxysilane), organic component is 1, An organic-inorganic composite filler comprising a cured product of 6-bis(methacrylethyloxycarbonylamino)trimethylhexane.

[Polymerization initiator]
· C-1: benzoyl peroxide.

[Pigment]
・Red pigment (pigment red)
・Yellow pigment (pigment yellow)
・Blue pigment (pigment blue)
・White pigment (titanium oxide)

Example 1
(1) First paste polymerizable composition (first fluid paste): Preparation of 1-1 A-1: 25 parts by mass and A-2: 75 parts by mass are mixed to form a polymerizable monomer composition ingredients were prepared. Separately, B-1: 50 parts by mass, CF-1: 50 parts by mass, B-2: 0.05 parts by mass and C-1: 0.4 parts by mass are mixed to prepare a filler composition. did. Then, 18% by mass of the polymerizable monomer composition is added to 82% by mass of the filler composition, and red, yellow, blue, and white pigments are added to 0.2 parts by mass of each of these mixtures. , 0.08, 0.17, and 0.02 parts by mass were added and mixed using a planetary mixer until uniform, followed by vacuum defoaming to prepare a first fluid paste: 1-1. B-1 and CF-1 impart light diffusibility to the cured body of the first fluid paste.

(2) Second paste-like polymerizable curable composition (second fluid paste): Preparation of 2-1 Types and amounts of pigments to be added (parts by mass with respect to 100 masses of the mixture) are selected from red, yellow, blue, and white pigments. 0.25, 0.11, 0.19 and 0.01 parts by weight of these mixtures were replaced with 0.25, 0.11, 0.19 and 0.01 parts by weight, respectively.

(3) Intermediate paste-like polymerizable and curable composition (intermediate fluid paste): Preparation of 3-1 First paste-like polymerizable and curable composition: 1-1 and second paste-like polymerizable and curable composition: 2-1 and at a mixing ratio (mass ratio) of 1-1:2-1=1:1 to prepare an intermediate fluid paste.

(4) Production of HR laminate to be cut A formwork kit consisting of a combination of two formwork units having the same shape and an internal columnar cavity of 18.5 mm × 15 mm × 9.5 mm was prepared. , After slidably inserting an extrusion plate of 18.3 mm × 14.8 mm × 2.0 mm into each formwork kit to close the opening on the closing side, one formwork unit (first formwork unit) is filled with the first fluid paste and the intermediate fluid paste to produce a paste-filled first mold unit, and the other mold unit (second mold unit) is filled with the second fluid paste to form a paste-filled second A formwork unit was made. At this time, by adjusting the position of the extrusion plate, the thickness T ₁ of the first paste layer (first layer), the thickness T 1 of the second paste layer (second layer), and the thickness T ₁ of the intermediate paste layer (intermediate layer) The thickness T _M1 was set to T ₁ =T ₂ =6.8 mm and T _M1 =1.5 mm.

Next, the joint surfaces of both filling formwork units are joined by adopting the convex curved surface joining method of the present embodiment to prepare a paste laminate filling connection formwork, and then polymerization and curing are performed to form the HR lamination that will be the cut part. got a body

(5) Evaluation of cured body of each fluid paste and HR laminate Contrast ratio (Y _b /Y _W ) of cured body of each fluid paste, cured body of first paste-like polymerizable curable composition and second paste-like polymerization The color difference of the cured body of the curable composition: ΔE ^* and the appearance evaluation of the HR laminate were performed as follows. Table 3 shows the results.

[Contrast ratio measurement]
Each fluid paste is molded into a cured body sample having a shape of 30 mm in diameter and 1.00 ± 0.01 mm in thickness, and the Y value of the tristimulus value is measured using a color difference meter (manufactured by Tokyo Denshoku, TC-1800MKII). Measured in black and white. A contrast ratio (Y _b /Y _W ) was calculated based on the following formula.
Contrast ratio = Y value for black background (Y _b )/Y value for white background (Y _W ).

[Color difference measurement]
A cured body sample having a shape of 30 mm in diameter and 1.00 ± 0.01 mm in thickness was molded from each of the first and second fluid pastes, and a color difference meter (manufactured by Tokyo Denshoku, TC-1800MKII) was used to measure the background color. Measurements of L ^* , a ^* , and b ^* were performed. Color difference: ΔE ^* was obtained by the following formula based on the obtained difference between each value, ΔL ^* , Δa ^* and Δb ^* .
ΔE ^* = {(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² } ^1/2

[HR Laminate Appearance Evaluation]
The appearance of the HR laminate was visually evaluated and evaluated according to the following four grades.
A: Very natural gradation B: Natural gradation C: Inconspicuous transition layer D: Transition layer looks unnatural.

Examples 2-18 and Comparative Examples 1-2
First fluid pastes: 1-2 and 1-3 were prepared in the same manner as in the preparation of the first fluid paste: 1-1 in Example 1, except that the raw material compositions were changed as shown in Table 1. Intermediate fluid paste: 3 was prepared in the same manner except that the type of the first fluid paste and the mixing ratio of the first fluid paste and the second fluid paste used in the preparation of intermediate fluid paste 3-1 were changed as shown in Table 2. -2 to 3-5 were prepared. Then, in the same manner as in Example 1 except that the combinations and layer thicknesses shown in Table 3 are obtained, the paste-filled first and second formwork units are produced, the paste laminate-filled connection formwork is produced, and polymerization and curing are performed. , to obtain the HR laminate of each example.
The parts by mass of B-1 and CF-1 in Table 1 represent the parts by mass of the filler composition, and the ppm of the pigment is the mass ratio (mass ppm).

In addition, the same evaluation as in Example 1 was performed for each paste-like polymerizable composition cured product and HR laminate. Tables 3 and 4 show the results. Note that "↑" in Tables 2 to 4 means "same as above".

1 dental working block 1a first layer 1a' first HR layer 1b second layer 1b' second HR layer 1c intermediate layer 1c' intermediate HR layer 2 blank retaining pins 3 first formwork unit 3a ejector plate 3b closing side opening 3c supply Side opening 4 Second mold unit 4a Ejection plate 4b Closing side opening 4c Supply side opening 5 Filler 5a Holding plate 5a1 Projection 5b Positioning block 5b1 Step 5c Filling plate 5c1 Support surface 5c2 Paste channel 5c3 Paste channel 5d Mold Frame unit housing part 5e Filling nozzle 6 Stacking device 6a Holding plate 6a1 Positioning pin 6a2 Through hole 6b Push-up plate 6b1 Push-up rod 7 Form unit holding device 7a, 7b Holding frame 7c Bottom plate 7d Pushing block 10 Dental prosthesis P Fluid paste Pa Paste joint surface

Claims (3)

A blank for dental processing having a portion to be cut comprising a hardened body of a paste laminate obtained by laminating a plurality of layers of a paste-like polymerizable composition containing a polymerizable monomer, an inorganic filler and a polymerization initiator. in the method
A: A formwork kit consisting of a first formwork unit and a second formwork unit, each consisting of a cylindrical body with both ends open and a columnar cavity formed therein, wherein these two formwork units are By connecting the cylindrical bodies in the axial direction, a connecting form having a connecting cylindrical body and a connecting columnar cavity formed by connecting the cylindrical bodies and the columnar cavities of both formwork units is formed. preparing the formwork kit to obtain;
B: A first paste-like polymerizable composition and a second paste-like polymerizable composition having different color tones, and one or two types of intermediate-colored pastes having intermediate colors of the color tones of these paste-like polymerizable and hardenable compositions. preparing a polymerizable curable composition;
C: The first mold unit is filled with the first pasty polymerizable composition and one of the one or two intermediate color paste polymerizable compositions to have a uniform thickness. Paste filling filled in the first mold unit in a state in which the first paste-like polymerizable composition layer and the one kind of intermediate color paste-like polymerizable composition layer having a uniform thickness are laminated. While producing the first formwork unit,
When there are two types of the second paste-like polymerizable and curable composition in the second mold unit, or the second paste-like polymerizable and curable composition and the one or two neutral color paste-like polymerizable and curable compositions The paste-filled second mold unit in which the second mold unit is filled with the second paste-like polymerizable composition by filling with the other one in the second mold unit, or the second mold unit having a uniform thickness Paste filled in the second formwork unit in a state in which two paste-like polymerizable composition layers and the other neutral color paste-like polymerizable composition layer having a uniform thickness are laminated. making a filled second formwork unit;
D: The paste-filled first mold unit and the paste-filled second mold unit obtained in the above steps are divided into the first paste polymerizable composition layer and the second paste polymerizable composition layer. are connected so as to be laminated via the one or two intermediate color paste-like polymerizable composition layers to form the connecting form, and in the connecting columnar cavity, each paste filling mold A step of obtaining a paste laminate filling connection formwork by joining the pasty polymerizable composition filled in the frame unit to form a paste laminate;
E: A curing step of curing the paste laminate inside the connecting columnar cavity to form a cured body;
including
In the step C, the thicknesses of the layers of the first pasty polymerizable composition and the one intermediate color paste polymerizable composition filled in the paste-filled first mold unit are each set to _T1 and _TM1 , and the thicknesses of the layers of the second paste polymerizable composition and the other neutral color paste polymerizable composition filled in the paste-filled second mold unit, respectively, When T ₂ and T _M2 , the following formulas (1) to (3)
T _M1 /(T ₁ +T _M1 )=0 to 0.30 (1)
T _M2 /(T ₂ +T _M2 )=0 to 0.30 (2)
(T _M1 +T _M2 )/(T ₁ +T _M1 +T ₂ +T _M2 )=0.01 to 0.30
(3)
satisfies all the relationships shown in
In the step C, each of the first mold unit and the second mold unit has a flat contact surface in contact with the pasty polymerizable and curable composition filled in the columnar cavity, An extruding plate for extruding the pasted polymerizable composition from the supply side opening, which is the opening on the other side, is inserted in the columnar cavity so as to be advanceable and retractable and detachable from one end of each formwork unit. After closing the closing side opening, which is the opening, in the columnar cavity, the contact surface of the first mold unit is brought into contact with the first pasty polymerizable composition, and the second mold unit In the above, the contact surface is in contact with the second paste polymerizable composition, and the paste polymerizable composition is densely filled, so that the closing side opening, which is one side opening, is the extrusion The paste-filled first mold unit and the paste-filled second mold, which are closed with a plate and have a planar or substantially planar paste bonding surface formed in the supply side opening, which is the opening on the other side. Create a frame unit,
The step D is
Da1: For at least one of the paste-filled first mold unit and the paste-filled second mold unit, the extrusion plate is moved toward the supply side opening to extrude the pasty polymerizable and curable composition, and the a step of projecting a portion of the paste-like polymerizable composition from the supply-side opening to form a convex curved surface on the paste joint surface; and
Da2: After the step, both paste-filled formwork units are connected so that the paste-joining surface of the paste-filled first formwork unit and the paste-joint surface of the paste-filled second formwork unit overlap, and A connecting mold is formed, and the pasty polymerizable and curable composition filled in both paste filling mold units is joined in the connecting columnar cavity to form the paste laminate, and the connecting mold is formed. A step of obtaining the paste laminate filling connection formwork in which both end openings of are substantially closed with the extrusion plate;
including
A method for manufacturing a blank for dental processing, characterized by: 2. The method for producing a dental processing blank according to claim 1, wherein T _M1 /(T ₁ +T _M1 ) is greater than 0 and equal to or less than 0.30. 2. The method for manufacturing a dental work blank according to claim 1, wherein T _M1 /(T ₁ +T _M1 ) is between 0.05 and 0.25.

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