JP2022055509A - Laminated type resin-based dental cutting blank - Google Patents

Abstract

To provide resin-based dental cutting blanks that can naturally match the color tone of natural teeth of many patients even when a dental prosthesis is made that includes a part where there is no natural tooth in a base in a relatively wide range from the vicinity of the tooth cervix to the cutting-edge part.SOLUTION: A part to be cut of a resin-based dental cutting blank is made up of a hybrid resin laminate having a laminated structure, in which a first layer made of a structural color-based hybrid resin that does not substantially contain a pigment or the like and can be adapted to the surrounding color tone by expressing the structural color of a specific color tone regardless of the incident angle of light and a second layer made of a hybrid resin colored in a different color tone by blending a pigment or the like are joined, the hybrid resin laminate having a color difference between both layers: ΔE* of 2 to 30.SELECTED DRAWING: None

Description

The present invention relates to a laminated dental cutting mill blank having a workpiece to be machined composed of a laminated body in which a plurality of resin-based material layers are laminated.

In dental treatment, the use of digitization technology is advancing in the production of dental restorations (or dental prostheses) such as inlays, onlays, crowns, bridges and implant superstructures. For example, as disclosed in Patent Document 1, a CAD / CAM device using computer-aided design (CAD) (Computer Aided Design) and computer-aided manufacturing (CAM) (Computer Aided Manufacturing) technology can be obtained from an image taken in the oral cavity. A CAD / CAM system for forming a dental restoration by cutting a blank for dental cutting made of a non-metal material has come to be widely used. Here, the blank for dental cutting means a workpiece (also referred to as a mill blank) that can be attached to a cutting machine in a CAD / CAM system, and is formed into a rectangular parallelepiped or a cylindrical shape (solid). ) Blocks or (solid) discs formed in the shape of plates or discs are generally known. A holding pin for fixing this to the cutting machine is often joined to the blank for dental cutting, and in such a form, a blank integrated with the holding pin is called a blank for dental cutting. Sometimes. In the present invention, it is referred to as a blank for dental cutting including a form integrated with such a holding pin. The body to be machined (blank body for dental cutting) may also be referred to as a machined portion.

Various materials such as glass ceramics, zirconia, titanium, and resin are used as the material to be the machined portion of the blank for dental cutting. Among these, a resin-based material (also referred to as a hybrid resin) composed of an inorganic filler such as silica, a polymerizable monomer such as a methacrylate resin, and a cured product of a curable composition containing a polymerization initiator is the work thereof. It is attracting attention because of its high properties (cutting workability), high aesthetics, and strength.

By the way, in dental treatment, it is required to give an appearance as close as possible to the color tone of natural teeth, and in order to satisfy such aesthetic requirements, pigment substances and dye substances are selected in their types and blending amounts. There are single-layered resin-based blanks for dental cutting, which consist of a single component whose color tone has been adjusted by changing the color tone, and multi-layered resin-based blanks for dental cutting, which are composed of laminated components of different color tones. Proposed.

For example, Patent Document 2 describes a resin layer for dentin restoration and a resin layer for enamel restoration as a resin-based blank for dental cutting, which is excellent in versatility and productivity and has high reproducibility of the aesthetic appearance of natural teeth. A resin block for dental CAD / CAM in which and is laminated, and at least the resin layer for dentin restoration contains light-diffusing particles, and a resin block for dental CAD / CAM having a specific diffusion ratio has been proposed. There is. Further, in Patent Document 3, as a dental mill blank capable of providing a dental prosthesis having a color tone and transparency more similar to that of natural teeth by cutting, the laminated body is intermediate between the uppermost layer and at least one layer. Each layer comprising a layer and at least three layers of the bottom layer and constituting the laminate contains a filler (A) and a polymer (B), and the filler (A) of each layer is at least one kind of inorganic material. It contains particles (a) and at least one pigment (C), and the chromaticity difference ΔE * _T between the top layer and the bottom layer is 5.0 or more and 15.0 or less, and the top layer and the bottom layer The transparency difference ΔΔL * _T is 5.0 or more and 15.0 or less, the chromaticity difference ΔE * of all adjacent layers is 1.0 or more and 5.5 or less, and the transparency difference ΔΔL * of all adjacent layers. Is 1.0 or more and 5.0 or less, the transparency ΔL * _H of the uppermost layer is 13.5 or more and 25.0 or less, and the transparency ΔL * _L of the lowermost layer is 7.0 or more and 13.0 or less. There is a dental mill blank proposed.

Further, it is known that a resin-based blank for dental cutting having a single-layer structure can achieve color harmony with natural teeth by expressing a so-called structural color without using a pigment or the like. That is, Patent Document 4 describes a resin-based block for dental cutting that contains a resin matrix (A) and a spherical filler (B) having an average particle size in the range of 230 nm to 1000 nm. More than 90% of the individual particles constituting B) are present within the range of 5% before and after the average particle diameter, and are measured with a color difference meter at a thickness of 10 mm under a black background and under a white background. The brightness (V) of the colorimetric value measured by the Mansell color system of the colored light in the above was less than 5.0, the saturation (C) was less than 2.0, and the measurement was performed using a color difference meter at a thickness of 1 mm. , The lightness (V) of the colorimetric value measured by the Mansell color system of colored light under a black background is less than 5.0, the saturation (C) is 0.05 or more, and coloring under a white background. "Resin-based block for dental cutting, characterized in that the lightness (V) of the colorimetric value measured by the Mansell color system of light is 6.0 or more and the saturation (C) is less than 2.0" is disclosed. Has been done. According to Patent Document 4, 90% or more of the individual particles constituting the spherical filler (B) are present in the range of 5% before and after the average particle diameter in the resin-based block for dental cutting. The resin matrix (A) and the spherical filler (B) have a refractive index of the resin matrix (A) at 25 ° C. of nP and a refractive index of the spherical filler (B) at 25 ° C. of nF. In addition, by satisfying the condition of nP <nF, colored light of a specific color tone is expressed as a structural color according to the particle size of the spherical filler (B), and under a black background, it is peculiar according to the colored light. It is clearly confirmed as a reflection spectrum, but under a white background, it shows a substantially uniform refractive index over substantially the entire range of the visible spectrum, and shows the property that light in the visible spectrum is not confirmed, and various peripherals. It is explained that the effect of being in harmony with the environment is exhibited.

Regarding the composite material in which the inorganic particles are dispersed in the resin matrix, which corresponds to the hybrid resin to be the machined portion of the resin-based block for dental cutting shown in Patent Document 4, the shape of the inorganic particles and the shape of the inorganic particles When the particle size distribution, the relationship between the refractive index of the inorganic particles and the refractive index of the resin matrix, and the dispersed state of the inorganic particles satisfy specific conditions, a structural color with a constant color tone that is not affected by changes in the incident angle of light. It is known to develop color (see Patent Document 5).

Special Table 2016-535610 Japanese Unexamined Patent Publication No. 2017-21334 International Publication No. 2018/074605 International Publication No. 2019/189698 Pamphlet International Publication No. 2020/050123 Pamphlet

In natural teeth, the cervical part is opaque and has a strong reddish-yellowish color, and the color gradually changes to a white transparent color toward the incision. There are individual differences in the overall color tone (sometimes called shade). Therefore, in order to reproduce the color tone of natural teeth to a high degree, in order to reproduce the color tone change from the cervical part to the incisal part for each overall color tone (shade), a multi-layered mill blank (hereinafter, different color tones) , Also called "multi-layer mill blank"), which not only requires labor in manufacturing, but also carefully checks the tooth shade of each individual patient before use, and is suitable for it from among many candidates. It is necessary to select a multi-layer mill blank.

On the other hand, the resin block for dental cutting (hereinafter, also referred to as "structural color resin blank") having a processed portion made of a hybrid resin expressing a structural color described in Patent Document 4 was used. In some cases, the effect makes it possible to harmonize the color of the dental prosthesis produced using it with the color of the underlying natural tooth.

However, when the present inventors have conducted various studies on dental prostheses prepared by using the structural color resin-based blank described in Patent Document 4, depending on the embodiment, highly aesthetic restoration is performed. It turns out that it may not be possible. That is, in a dental prosthesis including a portion where no natural tooth is present in the base in a relatively wide range from the vicinity of the cervical part to the incisal part, for example, an anterior tooth crown which is a dental prosthesis for repairing an anterior tooth. It was found that the structural color was not observed and the color tone adjustment effect could not be obtained, as in the case of under a white background.

Therefore, the present invention makes the best use of the advantage of the structural color resin blank in terms of color tone compatibility even when a dental prosthesis including a portion where natural teeth do not exist in the base is produced, and various surrounding environments. It is an object of the present invention to provide a resin-based blank for dental cutting that can be widely harmonized with each other.

The present inventors have studied to solve the above problems. As a result, when a colored hybrid resin layer is provided as a lower layer of a layer made of a hybrid resin that expresses a structural color, even when a dental prosthesis including a portion where natural teeth do not exist in the base is produced. , The "effect of being widely harmonious with various surrounding environments" of the layer made of hybrid resin that expresses structural color is exhibited, and when the color difference between the two layers is within a specific range, it is natural. We have found that a gradation effect can be obtained, and have completed the present invention.

That is, one embodiment of the present invention is a resin blank for dental cutting, which has a processed portion made of a composite material in which inorganic particles are dispersed in a resin matrix.
The composite material has a laminated structure in which the first layer and the second layer are joined.
The first layer is made of a first composite material which is a composite material that develops a structural color of a predetermined color tone regardless of the incident angle of light.
The second layer is made of a second composite material made of a composite material having a color tone different from that of the first composite material.
The color tone of the composite material having a single color tone is shown by the L ^* value, a ^* value and b ^* value obtained by measuring the sample with a thickness of 1.0 ± 0.1 mm with a fair background using a spectrophotometer. When you do
The following formula ΔE ^* = {(L1 ^* -L2 ^* ) ² + (a1 ^* -a2 ^* ) ² + (b1 ^* -), which is an index of the difference between the color tone of the first composite material and the color tone of the second composite material. b2 ^* } ^1/2
(In the above formula, L1 ^* , a1 ^* and b1 ^* are the L ^* value, a ^* value and b ^* value in the first composite material, and L2 ^* , a2 ^* and b2 ^* are the second composite material. L ^* value, a ^* value and b ^* value in.)
A resin-based blank for laminated dental cutting, characterized in that the color difference defined in the above: ΔE ^* is 2 to 30.

In the resin-based blank for laminated dental cutting of the above form (hereinafter, also referred to as "blank of the present invention"), the first composite material satisfies all the conditions shown in the following (a) to (d). Is preferable.
(A) The inorganic particles are composed of aggregates of inorganic spherical particles having a predetermined average primary particle diameter in the range of 100 nm to 1000 nm, and 90% or more of the total number of particles in the number-based particle size distribution of the aggregates. It contains one or more spherical particle groups (G-PIDs) of the same particle size existing in the range of 5% before and after the predetermined average primary particle diameter.
(B) Let a be the number of the spherical particles having the same particle size contained in the inorganic particles, and G-PIDm (where m is a) for each group of spherical particles having the same particle size in ascending order of the average primary particle diameter. When is 1, it is 1, and when a is 2 or more, it is a natural number from 1 to a.) When a is 2 or more, the average primary particle diameter of each G-PIDm is They differ from each other by 25 nm or more.
(C) The refractive index of the resin matrix with respect to light having a wavelength of 589 nm at 25 ° C. is n (MX), and the refractive index of the inorganic spherical particles constituting each G-PIDm with respect to light having a wavelength of 589 nm at 25 ° C. is n (G-). When PIDm) is set, for any n (G-PIDm),
n (MX) <n (G-PIDm)
The relationship is established.
(D) In the first composite material, it is a function representing the probability that another inorganic spherical particle exists at a point r away from the center of the arbitrary inorganic spherical particle, and is an observation plane of the inner surface of the composite material. The average particle density of the inorganic spherical particles in the observation plane determined based on the scanning electron microscope image: <ρ>, and a circle having a distance r from any inorganic spherical particles in the observation plane. The following equation (1) is based on the number of inorganic spherical particles existing in the region between the circles having a distance r + dr: dn, and the area of the region: da (where da = 2πr · dr).
g (r) = {1 / <ρ>} × {dn / da} ... (1)
Function defined in: When g (r) is a radial distribution function, the inorganic spherical particles constituting all the "spherical particle groups of the same particle size" (G-PID) in the composite material are in the following condition 1. And are dispersed in the matrix material so as to have a short-range ordered structure that satisfies the following condition 2.
[Condition 1]: The standard is obtained by dividing the distance from the center of any inorganic spherical particles dispersed in the composite material by the average particle diameter of all the inorganic spherical particles dispersed in the composite material: _r0 . With the converted non-dimensional number (r / r ₀ ) as the x-axis and the radial distribution function: g (r) as the y-axis, the r / r ₀ and the g (r) corresponding to r at that time In the radial distribution function graph showing the relationship, among the peaks appearing in the radial distribution function graph, the closest particle distance: r ₁ defined as r corresponding to the peak top of the peak closest to the origin is described above. The average particle size of all the inorganic spherical particles dispersed in the composite material: a value of 1 times or more and 2 times or less of _r0 .
[Condition 2]: Among the peaks appearing in the radial distribution function graph, when r corresponding to the peak top of the peak second closest to the origin is the distance between the next closest particles: r ₂ , the closest particles The minimum value of the radial distribution function: g (r) between the distance: r ₁ and the distance between the next adjacent particles: r ₂ is a value of 0.56 or more and 1.10 or less.

Further, the total blending amount of the pigment and the dye in the first composite material is 100% by mass or less with respect to the total mass of the first composite material, and the total blending amount of the pigment and the dye in the second composite material is the first. (2) It is preferably 500 to 7000 mass ppm with respect to the total mass of the composite material.

Further, the transparency of the composite material is obtained when the color difference is measured with a spectrophotometer for a sample with a thickness of 1.0 ± 0.1 mm. Y value on a white background: Y on a black background with respect to Y _W. When the value determined as the value: Y _B / ratio: Y _B / Y _W is expressed using the contrast ratio: CR as an index, the contrast ratio of the first composite material: CR1 is 0.28 to 0.46. The contrast ratio of the second composite material: CR2 is preferably 0.50 to 0.65.

In the laminated dental cutting resin blank of the present invention, even when a dental prosthesis including a portion in which natural teeth do not exist in the underlying layer is produced in a relatively wide range from the vicinity of the cervical region to the incisal portion, the incisal portion is formed. Is composed of the first layer, and the vicinity of the cervical part is composed of the second layer. It will be possible to reproduce the color tone of natural teeth more. Moreover, since the first layer is made of a hybrid resin that expresses a structural color, the color tone naturally matches the color tone of the second layer. Therefore, it is sufficient to adjust the color tone using pigments and dyes only for the second layer near the cervical region. Therefore, as compared with the case where the chromaticity difference and the transparency difference between the three layers are highly adjusted and laminated as in the method disclosed in Patent Document 3, the labor required for the adjustment and the lamination is significantly reduced, and the manufacturing efficiency is improved. Greatly improved. Further, it is possible to reduce the trouble of shade taking at the time of use.

1. 1. About the outline of the blank of the present invention The resin-based blank for laminated dental cutting of the present invention has a machined portion made of a composite material (corresponding to a hybrid resin) in which inorganic particles are dispersed in a resin matrix. In the resin-based blank for dental cutting, the composite material (hybrid resin) constituting the machined portion has a laminated structure in which the first layer and the second layer are joined, and the first layer is light. The second layer is made of a first composite material which is a composite material that expresses a structural color of a predetermined color tone regardless of the incident angle of the above, and the second layer is made of a composite material having a color tone different from that of the first composite material. It is composed of two composite materials, and is characterized in that the color difference: ΔE ^* , which is an index of the difference in color tone between the first composite material and the second composite material, is in a specific range. The second composite material constituting the second layer of the laminated structure may exhibit a structural color having a predetermined color tone regardless of the incident angle of light, and does not exhibit such a structural color. May be.

Further, in the laminated structure, the contrast ratio of the first composite material: CR1 is 0.28 to 0.46, in particular, because the color tone compatibility derived from the structural color of the first composite material becomes remarkable. It is 0.28 to 0.43, and the contrast ratio of the second composite material: CR2 is preferably 0.50 to 0.65, particularly preferably 0.55 to 0.63.

The blank of the present invention is not particularly different from the conventional hybrid resin-based dental cutting blank except that the machined portion has the above-mentioned laminated structure, and is fixed to a cutting machine such as a holding pin as necessary. It may have a holding member for the purpose. Further, the shape and size of the portion to be cut are not particularly limited, and may be a (solid) block formed in the shape of a rectangular parallelepiped or a cylinder, or a plate-shaped or disc-shaped (solid) disk. May be good.

The blank to be machined portion of the present invention may have a two-layer structure consisting of only the first layer and the second layer as long as it has the above-mentioned laminated structure, and may have a three-layer structure to which an additional layer is added. It may have the above laminated structure. The thickness of each layer is not particularly limited, but is usually in the range of 1 to 13 mm, preferably 2 to 12 mm.

When the composite material (hybrid resin) constituting the machined portion has a laminated structure of three or more layers, the side opposite to the side to be joined to the second layer of the first layer and / or the first of the second layer. It is preferable to have a three-layer or four-layer structure in which a layer made of another composite material (hybrid resin) is bonded to the side opposite to the side to be bonded to the layer. At this time, when a layer made of another composite material (hybrid resin) (also referred to as "first layer side additional layer") is bonded to the side opposite to the side to be bonded to the second layer of the first layer, It is preferably made of a composite material (hybrid resin) having a contrast ratio lower than that of CR1 and expressing a structural color having a predetermined color tone regardless of the incident angle of light. Further, when a layer made of another composite material (hybrid resin) (also referred to as "second layer side additional layer") is bonded to the side opposite to the side to be bonded to the first layer of the second layer, the first layer is used. Contrast ratio of the second composite material: It is preferable to use a composite material (hybrid resin) having a contrast ratio higher than that of CR2, particularly a composite material (hybrid resin) that does not develop a structural color. Further, the color difference between the second layer and the second layer side additional layer is preferably 1 to 10, and more preferably 2 to 8.

As described above, when the structural color resin blank described in Patent Document 4 is used to prepare a dental prosthesis for a relatively wide range from the vicinity of the cervical region to the incisal region, a dental prosthesis for dental cavity restoration is produced. Similar to the case under a white background, the expressed structural color may not be observed due to the strong influence of transmitted light, and the color tone adjustment effect may not be obtained. On the other hand, since the machined portion has a laminated structure as described above, the influence of transmitted light can be reduced because the second layer is colored, so that the first layer is a structural color resin system. It will be possible to demonstrate the original characteristics of the blank. Therefore, even when a dental prosthesis including a portion where natural teeth do not exist in the base layer is produced, the vicinity of the cervical part is composed of the second layer and the vicinity of the incisal part is composed of the first layer. By producing the above, the portion composed of the first layer can be matched with the surrounding color tone without particularly performing color tone adjustment using a pigment or a dye. Further, since the color difference between the first layer and the second layer: ΔE ^* is within a certain range, a moderately blurred natural gradation can be seen between the two layers.

The first composite material constituting the first layer and the composite material to be the first layer side additional layer added as needed, and the second composite material and the second layer side additional layer to be added as needed. When the composite material develops a structural color, the second composite material and the composite material have a predetermined average (primary) particle diameter similar to the composite material used in the structural color resin-based blank described in Patent Document 4. And a structural color of a predetermined color that includes inorganic spherical particles having a predetermined particle size distribution and does not depend on the incident angle of light (according to the average particle size of the contained spherical particles of the same particle size) (hereinafter, "specific structural color"). It is also called.). As described above, for a composite material (hybrid resin) that expresses such a specific structural color, the conditions that must be satisfied in order to express the specific structural color are known (see Patent Document 5). The first composite material or the like in the present invention is a composite material that satisfies all of such conditions, specifically, the conditions (a) to (d) described later {conditions (a) to (d) described later. ) Satisfying all of the above and expressing a specific structural color is also hereinafter referred to as “structural color-based hybrid resin”. } Can be used without any particular restrictions.

On the other hand, when the second composite material and the composite material to be the second layer side additional layer added as needed do not develop the structural color, the above conditions are not satisfied {condition (a) described later). Not satisfying at least one of (d)} A hybrid resin or a hybrid resin in which the expression of a specific structural color cannot be visually confirmed due to a large amount of a pigment or the like (hereinafter, collectively referred to as "non-structural color hybrid"). Also called "resin") is used.

In the blank of the present invention, it is extremely important that the first composite material and the second composite material constituting the first layer and the second layer in the laminated structure have specific characteristics, respectively. Therefore, first, these After explaining the characteristics, that is, the structural color, the conditions for the specific structural color and the hybrid resin to develop the specific structural color, and the contrast ratio and the color difference, the raw materials such as the first composite material and the second composite material and their preparation thereof. The method, a method for producing a blank of the present invention, and the like will be described.

In the present specification, unless otherwise specified, the notation "x to y" using the numerical values x and y means "x or more and y or less". When a unit is attached only to the numerical value y in such a notation, the unit shall be applied to the numerical value x as well. Further, in the present specification, the term "(meth) acrylic type" means both "acrylic type" and "methacrylic type". Similarly, the term "(meth) acrylate" means both "acrylate" and "methacrylate", and the term "(meth) acryloyl" means both "acryloyl" and "methacryloyl".

2. 2. Structural color and specific structural color Structural color is a phenomenon in which light incident on an object having a fine structure reflects light of a specific wavelength due to interference, diffraction, refraction, etc. of the light due to the fine structure, and is an opal or an oil film. In such cases, different structural colors are observed depending on the incident angle (or viewing angle) of light. On the other hand, in the resin-based blank for laminated dental cutting of the present invention, as described above, a specific structural color in which a predetermined color is observed without depending on the incident angle of light is used.

It is known that the above-mentioned specific structural color is developed by dispersing fine particles having a uniform particle size so as to have an overall amorphous structure while having a specific short-range ordered structure, and it is a dental material. Also, a single-layer resin-based block for dental cutting (see Patent Document 4), which is composed only of a resin-based material using a specific structural color, specifically, a composite material expressing such a structural color, has been developed. There is. In the hybrid resin, which is a resin-based material in which inorganic particles are dispersed in a resin matrix, the conditions necessary for developing a specific structural color have been clarified.

3. 3. Conditions to be Satisfied with Structural Color Hybrid Resin As disclosed in Patent Document 5, in order for a hybrid resin to express a specific structural color, it is necessary to satisfy all of the following conditions (a) to (d). be.

(A) The inorganic particles are composed of aggregates of inorganic spherical particles having a predetermined average primary particle diameter in the range of 100 nm to 1000 nm, and 90% or more of the total number of particles in the number-based particle size distribution of the aggregates. One or more spherical particle groups (G-PID) having the same particle size existing in the range of 5% before and after the predetermined average primary particle diameter.
(B) Let a be the number of the spherical particles having the same particle size contained in the inorganic particles, and G-PIDm (where m is a) for each group of spherical particles having the same particle size in ascending order of the average primary particle diameter. When is 1, it is 1, and when a is 2 or more, it is a natural number from 1 to a.) When a is 2 or more, the average primary particle diameter of each G-PIDm is They must be 25 nm or more different from each other.
(C) The refractive index of the resin matrix with respect to light having a wavelength of 589 nm at 25 ° C. is n (MX), and the refractive index of the inorganic spherical particles constituting each G-PIDm with respect to light having a wavelength of 589 nm at 25 ° C. is n (G-). When PIDm) is set, the relationship of n (MX) <n (G-PIDm) is established for any n (G-PIDm).
(D) A function representing the probability that another inorganic spherical particle exists at a point r away from the center of the arbitrary inorganic spherical particle in the composite material (hybrid resin), and is an internal surface of the composite material. Average particle density of the inorganic spherical particles in the observation plane: <ρ>, and a distance r from any inorganic spherical particles in the observation plane, which is determined based on a scanning electron microscope image with the observation plane as the observation plane. Based on the number of inorganic spherical particles existing in the region between the circle of the distance r + dr and the area of the region: da (where da = 2πr · dr), the following equation (1) )
g (r) = {1 / <ρ>} × {dn / da} ... (1)
Function defined in: When g (r) is a radial distribution function, the inorganic spherical particles constituting all the "spherical particle groups of the same particle size" (G-PID) in the composite material are in the following condition 1. And it is dispersed in the matrix material so as to have a short-range ordered structure that satisfies the following condition 2.

[Condition 1]: The standard is obtained by dividing the distance from the center of any inorganic spherical particles dispersed in the composite material by the average particle diameter of all the inorganic spherical particles dispersed in the composite material: _r0 . With the converted non-dimensional number (r / r ₀ ) as the x-axis and the radial distribution function: g (r) as the y-axis, the r / r ₀ and the g (r) corresponding to r at that time In the radial distribution function graph showing the relationship, among the peaks appearing in the radial distribution function graph, the closest particle distance: r ₁ defined as r corresponding to the peak top of the peak closest to the origin is described above. The average particle size of all the inorganic spherical particles dispersed in the composite material: a value of 1 times or more and 2 times or less of _r0 .
[Condition 2]: Among the peaks appearing in the radial distribution function graph, when r corresponding to the peak top of the peak second closest to the origin is the distance between the next closest particles: r ₂ , the closest particles The minimum value of the radial distribution function: g (r) between the distance: r ₁ and the distance between the next adjacent particles: r ₂ is a value of 0.56 or more and 1.10 or less.

The radial distribution function: g (r) generally has the distance r on the x-axis (distance axis) and the value of g (r) on the y-axis (vertical axis) {the above formula. A radial distribution function graph with the calculation result from (1)}, or a non-dimensional number normalized by dividing the r by the average particle diameter of the particles on the distance axis, and the x-axis on the y-axis (vertical axis). It is represented by a radial distribution function graph taking the value of g (r) (calculation result of the above equation) in r corresponding to the value of.

Regarding <ρ> and dn, <ρ> and dn, which were determined based on a scanning electron microscope image in which the inner surface of the first composite material is the observation plane, because it is easy and reliable to confirm. Further, it is preferable to adopt g (r) calculated by the above equation (1) based on the value of dr adopted when determining the above dn: da (= 2πr · dr).

The determination of <ρ>, dn and da based on the scanning electron microscope image with the inner surface of the first composite material as the observation plane can be performed as follows. That is, first, a composite material is produced by curing a polymerization curable composition which is a raw material of the first composite material, and then the surface of the obtained composite material is polished by means such as polishing an inorganic spherical shape inside the composite material. A plane (observation plane) in which the dispersed state of particles can be observed is exposed on the surface. Next, the observation plane is observed with a scanning electron microscope, and a microscope image of a region containing at least 500 or more inorganic spherical particles in the plane is acquired. Then, the coordinates of the inorganic spherical particles in the region are obtained from the obtained scanning electron microscope image using image analysis software (for example, "Simple Digitizer ver3.2" free software). Select one of the coordinates of any inorganic spherical particle from the obtained coordinate data, draw a circle with the radius r containing at least 200 or more inorganic spherical particles around the selected inorganic spherical particle, and draw the circle. The average particle density <ρ> (unit: pieces / cm ² ) can be determined by counting the number of inorganic spherical particles contained therein.

For dn, when the average particle size of the inorganic spherical particles is expressed by r ₀ , a dr whose length is about r _0/100 to r _0/10 is set and arbitrarily selected 1. The number of inorganic spherical particles contained in the region between a circle having one inorganic spherical particle as a central particle and a radius r at a distance from the center and a circle having the same center as the circle and having a radius: r + dr. The dn can be determined by counting. Further, da, which is the area of the region between the two circles, is determined as 2πr · dr based on the actually set length of dr.

In the first composite material, the standard is obtained by dividing the distance from the center of any inorganic spherical particles dispersed in the composite material by the average particle diameter of all the inorganic spherical particles dispersed in the composite material: _r0 . The radial distribution function: g (r), which represents the probability that another inorganic spherical particle exists at a point r away from the center of the arbitrary inorganic spherical particle, with the converted non-dimensional number (r / r ₀ ) as the x-axis. ) Is the y-axis, and in the radial distribution function graph showing the relationship between the r / r ₀ and the g (r) corresponding to r at that time, among the peaks appearing in the radial distribution function graph, from the origin. Closest particle distance defined as r corresponding to the peak top of the nearest peak: r ₁ is 1 or more and 2 times or less the average particle size of all the inorganic spherical particles dispersed in the composite material: r ₀ . Must be a value (Condition 1). When r ₁ is less than 1 times r ₀ (r ₁ / r ₀ <1), the overlap of particles in the plane increases, and r ₁ exceeds twice r ₀ (r ₁ ). In the case of / r ₀ > 2), the particles do not exist in the vicinity of the selected central inorganic particles, so that the short-distance order is lost and the structural color is not expressed. That is, from the viewpoint of maintaining order over a short distance and facilitating the development of structural color, r ₁ / r ₀ is 1.0 or more and 2.0 or less, especially 1.0 or more and 1.5 or less. It is preferable to have.

Further, in the first composite material, among the peaks appearing in the radial distribution function graph, when r corresponding to the peak top of the peak _second closest to the origin is set to the next proximity particle distance: r2, the latest The minimum value of the radial distribution function: g (r) between the distance between tangent particles: r1 and the distance between _{next -} order close particles: r2 must be 0.56 or more and 1.10 or less (the value is also required). Condition 2). When the minimum value is less than 0.56, the long-range order of the arrangement structure of the inorganic spherical particles becomes high, and not only the incident angle dependence of the light of the developed structural color increases, but also the saturation of the composite material becomes high. Will be high, and it will be difficult to obtain color tone compatibility when used as a dental filling material. On the other hand, when the minimum value exceeds 1.10, the arrangement structure of the inorganic spherical particles becomes a random structure, it becomes difficult to obtain the desired reflection performance, and it becomes difficult to develop the desired structural color. .. That is, from the viewpoint of expressing the structural color and facilitating the color tone compatibility as a dental filling material, the minimum values are 0.56 or more and 1.10 or less, particularly 0.56 or more and 1.00 or less. It is preferable to have.

3. 3. About color difference: ΔE ^* Color difference: ΔE ^* is an index showing the degree of difference between the two colors, and the larger the value, the different the color tone of the two. The color difference in the present invention: ΔE ^* refers to each coordinate axis in the L ^* a ^* b ^* color space (color system) represented by L ^* for lightness, a ^{* for hue, and b * for} saturation for two color tones to be compared. It means ΔE ^* determined by the following equation using the difference (ΔL ^* , Δa ^* and Δb ^* ) for the numerical values (L ^* value, a ^* value and b ^* value).
ΔE ^* = {(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² } ^1/2
Further, the L ^* value, a ^* value and b ^* value of the composite material (hybrid resin) having a single color tone in the present specification are measured by a spectrophotometer using a sample having a thickness of 1.0 ± 0.1 mm. It shall mean L ^* , a ^* and b ^* obtained by measurement with a fair background. Specifically, the measured area is measured by the reflected light 0 ° d method (JIS Z8722) using a spectrophotometer (manufactured by Tokyo Denshoku, "TC-1800MKII", halogen lamp: 12V100W, measurement wavelength range 380 to 780nm). It is determined by L ^* , a _* and b ^* obtained by measuring the spectral reflectance of a white background (a state in which a standard white plate is superposed on a cured body and light-shielded) at 5 mmφ.

For example, the color difference between the first composite material and the second composite material: ΔE ^* is a spectrophotometer using a sample with a thickness of 1.0 ± 0.1 mm for each of the first composite material and the second composite material. L ^* , a ^* and b ^* in the first composite material are L1 ^* , a1 ^* and b1 ^* , and L ^* , a ^* and b ^* in the second composite material are L2 ^* , when the color difference is measured by If a2 ^* and b2 ^* are used,
ΔL ^* = L1 ^* -L2 ^*
Δa ^* = a1 ^* -a2 ^*
Δb ^* = b1 ^* -b2 ^*
Because it is
ΔE ^* = {(L1 ^* -L2 ^* ) ² + (a1 ^* -a2 ^* ) ² + (b1 ^* -b2 ^* ) ² } ^1/2
Will be.

The color difference can be adjusted mainly by blending a pigment and a dye with the second composite material and adjusting the color tone (L2 ^* , a2 ^* and b2 ^* ) thereof. At this time, even if the pigment and the dye are blended in the second composite material to the extent that the effect of the specific structural color expression of the first composite material is not impaired, the color tone (L1 ^* , a1 ^* and b1 ^* ) is adjusted. good. If the difference in color tone is significantly different, ΔE ^* increases, the laminated interface between layers can be clearly confirmed visually, and the gradation effect that naturally blurs the boundary tends to decrease.

The first composite material and the second composite material can be used because the first layer can exhibit the original characteristics of the structural color resin blank and can express a more natural gradation. Color difference: ΔE ^* needs to be 2 to 30, preferably 2 to 25, and more preferably 2 to 20.

3. 3. Contrast ratio: CR = Y _B / Y _W Contrast ratio: CR is an index of transparency of a composite material (resin-based material) in which inorganic particles are dispersed in a matrix resin. In the present invention, the thickness is 1. Determined as Y value in background color white: Y value in background color black: Y _B / ratio: Y _B / _{Y W obtained} when color difference measurement with a spectrophotometer is performed on a sample of 0 ± 0.1 mm. Means the value to be. The smaller the value of this contrast ratio: CR, the higher the transparency, and the larger the value, the lower the transparency.

Specifically, the contrast ratio is determined by the reflected light 0 ° d method (JIS Z8722) using a spectrophotometer (manufactured by Tokyo Denshoku Co., Ltd., “TC-1800MKII”, halogen lamp: 12V100W, measurement wavelength range 380 to 780 nm). It is determined by measuring the spectral reflectance of the background color black (light shielding state) and the spectral reflectance of the background color white (light shielding state in which a standard white plate is superposed on the cured body) at a measurement area of 5 mmφ.

The contrast ratio can be adjusted by adjusting the amount of an ultrafine particle group (G-SFP) composed of inorganic particles having an average primary particle size of less than 100 nm and a coloring substance such as a pigment or a dye.

In the resin-based blank for laminated dental cutting of the present invention, the value of the contrast ratio of the first composite material and the second composite material constituting the first layer and the second layer in the laminated structure included in the machined portion, respectively. However, it is preferable that each is within a predetermined range. That is, the contrast ratio of the first composite material: CR1 is preferably 0.28 to 0.46, and the contrast ratio of the second composite material: CR2 is preferably 0.50 to 0.65. When the value of CR1 is out of the above range, it tends to be difficult to observe a specific structural color, and it tends to be difficult to harmonize with the surrounding color tone. Further, when the value of CR2 is out of the above range, when a dental prosthesis including a portion where natural teeth do not exist in the underlying layer is produced, the first layer that develops the structural color has "various surrounding environments". It tends to make it difficult to exert the effect of being a widely harmonious area.

From the viewpoint of the effect, CR1 is preferably 0.28 to 0.46, particularly 0.28 to 0.43, and CR2 is preferably 0.50 to 0.65, particularly 0.55 to 0.63. Further, the difference from the contrast ratio: CR2-CR1 = ΔCR = ΔY _B / Y _W is preferably 0.10 or more, particularly preferably 0.12 to 0.27.

5. Regarding the raw materials of the structural color hybrid resin and its manufacturing method As described above, the first composite material constituting the first layer, the composite material to be the first layer side additional layer added as necessary, and the second composite When the material and the composite material to be the second layer side additional layer to be added as needed develop a structural color, the second composite material and the above composite material are structural color-based hybrid resins, and the second composite material is The second composite material that does not develop a structural color and the composite material that becomes the second layer side additional layer to be added as needed are non-structural color-based hybrid resins.

The structural color hybrid resin used in the present invention is described in claim 1 of Patent Document 5, except that an ultrafine particle group (G-SFP) is not essential from inorganic particles having an average primary particle diameter of 100 nm unfinished. There is no particular difference from the above-mentioned composite material, and the raw materials and the preparation method thereof are not particularly different from the raw materials and the preparation method described in claim 9 of Patent Document 5, except for the above points.

That is, a curable composition containing a polymerizable monomer, inorganic particles satisfying specific conditions, and a polymerization initiator is referred to as a raw material composition (hereinafter referred to as "structural color-based raw material composition"), and the structure thereof. A structural color-based hybrid resin such as a first composite material can be produced by setting the dispersed state of the inorganic particles in the color-based raw material composition to a specific dispersed state and then curing the mixture.

Here, the conditions that the inorganic particles should be satisfied with are as shown in the following (i) to (iii).
(I) It consists of an aggregate of inorganic spherical particles having a predetermined average primary particle size in the range of 100 nm to 1000 nm, and 90% or more of the total number of particles in the number-based particle size distribution of the aggregate is the predetermined average primary particle. The number of the same particle size spherical particle group (G-PID) existing in the range of 5% before and after the particle size is included, and the number of the same particle size spherical particle group is one or more.
(Ii) Let a be the number of the spherical particles having the same particle size contained in the inorganic particles, and G-PID _m (where m is) for each group of spherical particles having the same particle size in ascending order of the average primary particle diameter. When a is 1, it is 1, and when a is 2 or more, it is a natural number from 1 to a.) The average primary particle diameters of each G-PID _m differ from each other by 25 nm or more. That you are.
(Iii) The refractive index of the cured product of the polymerizable monomer at 25 ° C. is n _(MX) , and the refractive index of the inorganic spherical particles constituting each G-PID _m at 25 ° C. is n _{(G-PID m)} . When you do, for any n _(G-PIDm)
n _(MX) <n _(G-PIDm)
The relationship is established.

Further, the conditions of the dispersed state to which the structural color-based raw material composition is satisfactory are as shown in the following (I) and (II).
(I) The distance r from the center of any inorganic spherical particles dispersed in the cured body of the structural color-based raw material composition is the average particle diameter r of the entire inorganic spherical particles dispersed in the cured body of the raw material composition. The x-axis is a non-dimensional number (r / r ₀ ) standardized by dividing by ₀ , and the radius represents the probability that another inorganic spherical particle exists at a point r away from the center of the arbitrary inorganic spherical particle. In a radial distribution function graph showing the relationship between r / r ₀ and g (r) corresponding to r at that time, with the distribution function g (r) as the y-axis, the peaks appearing in the radial distribution function graph. Of these, the closest particle distance r ₁ defined as r corresponding to the peak top of the peak closest to the origin is 1 times the average particle diameter r ₀ of all the inorganic spherical particles dispersed in the cured body of the mixture. It should be double the value.
(II) Among the peaks appearing in the radial distribution function graph, when r corresponding to the peak top of the peak _second closest to the origin is the _next proximity particle distance r2, the closest particle distance r1 The minimum value of the radial distribution function g (r) between the above and the distance r ₂ between the next adjacent particles is a value of 0.56 to 1.10.

The above conditions (i) to (iii) correspond to the conditions (a) to (c) that the structural color hybrid resin should be satisfied with, and the curing of the polymerizable monomer contained in the structural color raw material composition. The body corresponds to the resin matrix of the structural color hybrid resin (for example, the resin matrix in the first composite material), and the inorganic particles contained in the structural color raw material composition are dispersed in the resin matrix of the structural color hybrid resin. (For example, inorganic particles dispersed in the resin matrix in the first composite material). Regarding the above condition (iii), the difference between n _(G-PIDm) and n _(MX) from the viewpoint of visibility and sharpness of structural color and color tone compatibility when used as a blank for dental cutting. Δn (= n _(G—PIDm) −n _(MX) ) is preferably 0.001 or more and 0.1 or less, and more preferably 0.002 or more and 0.1 or less. Most preferably, it is 0.005 or more and 0.05 or less.

Further, satisfying the above conditions (I) and (II) corresponds to the condition (a) that the structural color hybrid resin should be satisfied with.

The following are the raw materials for the structural color-based raw material composition that is the raw material for the structural color-based hybrid resin such as the first composite material (in other words, the cured product becomes the structural color-based hybrid resin for the first composite material and the like). Will be explained.

5-1. Polymerizable monomer as a raw material of the structural color-based raw material composition The polymerized monomer in the structural color-based raw material composition is a cured product of which is a resin matrix of a structural color-based hybrid resin. As the polymerizable monomer, a radically polymerizable monomer can be preferably used. The radically polymerizable monomer is not particularly limited, and can be appropriately selected and used from (meth) acrylic compounds, cationically polymerizable monomers such as epoxies and oxetane, and the like. For example, in order to obtain a dental polymerization curable composition, it is preferable to use a (meth) acrylic compound. Examples of suitable (meth) acrylic compounds include methyl (meth) acrylate, ethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth) acrylic acid, N- (meth) acryloylglycine, p-. Vinyl benzoic acid, 2- (meth) acryloyloxybenzoic acid, 6- (meth) acryloyloxyethyl naphthalene-1,2,6-tricarboxylic acid anhydride, 13- (meth) acryloyloxytridecane-1,1-dicarboxylic Acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, N-hydroxyethyl (meth) acrylamide, N, N- (dihydroxyethyl) ) (Meta) acrylamide, 2,2-bis (methacryloyloxyphenyl) propane, 2,2-bis [(3-methacryloyloxy-2-hydroxypropyloxy) phenyl] propane, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate , 1,6-bis (methacrylicethyloxycarbonylamino) trimethylhexane, trimethylolpropanetrimethacrylate, pentaerythritol tetramethacrylate, neopentylglycoldimethacrylate, 4,4-diphenylmethanediisocyanate and the like.

A plurality of types of these (meth) acrylate-based polymerizable monomers may be used in combination, if necessary.

As the polymerizable monomer, generally, a plurality of types of polymerizable monomers are used to adjust the physical properties (mechanical properties and adhesiveness to the dentin in dental applications) of the cured product which is the resin matrix of the structural color-based hybrid resin. At this time, the type and amount of the polymerizable monomer are adjusted so that the refractive index of the polymerizable monomer composition (mixture) at 25 ° C. is in the range of 1.38 to 1.55. It is desirable to set it from the viewpoint that the condition regarding the refractive index can be easily satisfied. That is, when a silica-titanium group element oxide-based composite oxide whose refractive index can be easily adjusted is used as the inorganic spherical particles, the refractive index at 25 ° C. is 1.45 to 1.58 depending on the content of the silica content. By setting the refractive index of the polymerizable monomer composition in the range of 1.38 to 1.55, the refractive index of the obtained cured product can be about 1.40 to 1.57. It can be adjusted within the range of, and it becomes easy to satisfy the above conditions. The refractive index of the polymerizable monomer or the cured product of the polymerizable monomer can be determined at 25 ° C. using an Abbe refractive index meter.

5-2. Inorganic particles used as a raw material for the structural color-based raw material composition The structural color-based raw material composition is usually 100 to 900 parts by mass, preferably 150 to 700 parts by mass of inorganic particles with respect to 100 parts by mass of the polymerizable monomer. Contains particles. The inorganic particles contained in the structural color-based raw material composition are also inorganic particles dispersed in the resin matrix of the structural color-based hybrid resin, and include one or a plurality of "spherical particle groups having the same particle size" (G-PID). .. In addition, in order to disperse the inorganic spherical particles constituting the G-PID in the matrix material so as to have a short-range ordered structure satisfying the above conditions, the inorganic particles have an average primary particle diameter other than the G-PID. It is preferable that the particle does not contain inorganic particles (regardless of its shape) in the range of 100 to 1000 nm. However, the ultrafine particle group (G-SFP) having an average primary particle diameter of less than 100 nm is unlikely to affect the short-range ordered structure, and the viscosity and structural color of the structural color-based raw material composition depend on the blending amount. Since it has a function of controlling the contrast ratio of the hybrid resin, it is preferably blended in the range of 0.1 to 40 parts by mass, particularly 0.2 to 30 parts by mass with respect to 100 parts by mass of the polymerizable monomer. ..

The structural color-based raw material composition is substantially free of coloring substances such as dyes and pigments (for example, when the concentration of the coloring substances is 100% by mass or less, preferably 50% by mass or less), and the G-SFP. By setting the blending amount in this range, the contrast ratio of the obtained structural color-based hybrid resin can be set to 0.28 to 0.46.

The compounding amount of the same particle size spherical particles: G-PID is usually the total amount of all G-PIDs contained (that is, the total amount of inorganic spherical particles), and is 100 to 100 parts by mass of the polymerizable monomer. It is 900 parts by mass. Since the structural color hybrid resin has appropriate transparency and the effect of expressing the structural color is high, the amount of the G-PID blended is such that the structural color raw material composition is an ultrafine particle group (G-SFP). When is not contained, it is preferably 100 to 900 parts by mass with respect to 100 parts by mass of the polymerizable monomer, and particularly preferably 150 to 700 parts by mass. When G- SFP is contained, it is preferable that the amount is obtained by subtracting the amount of G- SFP from the above-mentioned blending amount.

When a plurality of types of G-PIDs are contained, the total amount of each G-PID is the above in consideration of the color tone of the structural color of each G-PID and the desired color tone of the blank for dental cutting. The amount may be appropriately distributed within the range.

The details of the inorganic spherical particles, G-PID, G-SFP and the like constituting the inorganic particles will be described below.

(1) Inorganic Spherical Particles The inorganic spherical particles constituting the G-PID are not particularly limited as long as they satisfy the above-mentioned conditions for forming the G-PID. Examples of materials that can be preferably used are amorphous silica, silica / titanium group element oxide-based composite oxide particles (silica / zirconia, silica / titania, etc.), quartz, alumina, barium glass, strontium glass, and lanthanum glass. , Fluoroamorphous silicate glass, itterbium fluoride, zirconia, titania, colloidal silica and the like. Among these, since the refractive index can be easily adjusted, it is composed of a silica-titanium group element oxide-based composite oxide which is a composite oxide of silica and a titanium group element (group 4 element of the periodic table) oxide. It is preferable to use particles. In the silica-titanium group element oxide-based composite oxide, the refractive index at 25 ° C. can be changed in the range of about 1.45 to 1.58 depending on the content of the silica content. Specific examples of the silica / titanium group element oxide-based composite oxide particles include silica / titania, silica / zirconia, silica / titania / zirconia, and the like.

The inorganic spherical particles may be surface-treated with a silane coupling agent.

(2) Spherical particle group with the same particle size: G-PID
Group of spherical particles having the same particle size: G-PID is composed of an aggregate of inorganic spherical particles having a predetermined average primary particle diameter in the range of 100 to 1000 nm, and the individual inorganic spherical particles constituting the aggregate are. The aggregate is composed of substantially the same substance, and 90% or more of the total number of particles is present in the range of 5% before and after the predetermined average primary particle diameter in the number-based particle size distribution of the aggregate. Means.

The average primary particle size of the inorganic spherical particles referred to here is a photograph of G-PID taken with a scanning electron microscope, 30 or more particles observed in the unit field of view of the photograph are selected, and each primary particle is selected. It means the average value obtained by calculating the particle diameter (maximum diameter). Further, the spherical shape may be a substantially spherical shape, and does not necessarily have to be a perfect true sphere. Take a picture of G-PID with a scanning electron microscope, measure the maximum diameter of each particle (30 or more) in the unit field of view, and divide the particle diameter in the direction orthogonal to the maximum diameter by the maximum diameter. The average uniformity may be 0.6 or more, more preferably 0.8 or more.

In structural color hybrid resins such as the first composite material, each constituent particle of G-PID, which is an aggregate of inorganic particles in which the constituent inorganic particles are spherical and the particle size distribution (number-based particle size distribution) is narrow, is specific. By having a short-range ordered structure and dispersing in the resin matrix, diffraction interference occurs according to Bragg conditions, light of a specific wavelength is emphasized, and colored light having a color tone corresponding to the average primary particle size is generated ( Structural color appears). That is, in order for the structural color to appear, 90% (number basis) or more of the inorganic spherical particles constituting the G-PID must be present in the range of 5% before and after the average primary particle diameter. Further, in order to develop a structural color having a specific color tone in a wide range of blue to yellow to red, the average primary particle diameter of the inorganic spherical particles constituting G-PID is in the range of 100 to 1000 nm. There is a need. When the average primary particle size is 230 to 800 nm, a yellow to red structural color (colored light) is likely to appear, and when the average primary particle size is 150 nm to less than 230 nm, a bluish structural color (colored light) is likely to appear. Colored light) is likely to appear.

The average primary particle size of G-PID is preferably 230 to 800 nm, more preferably 240 to 500 nm, because it develops a yellow to red structural color (colored light) that is preferable as a restoration treatment for natural teeth. 260-350 nm is particularly suitable. When G-PID with an average primary particle diameter in the range of 230 nm to 260 nm is used, the obtained colored light is yellowish, and it falls into the category of B-based (red-yellow) in the shade guide (“VITAClasical”, manufactured by VITA). Useful for repairing certain teeth. Further, when G-PID having an average primary particle diameter in the range of 260 nm to 350 nm is used, the obtained colored light is red-based, and is in the category of A-based (reddish brown) in the shade guide (“VITAC Classic”, manufactured by VITA). It is useful for repairing teeth in. Since most of the hues of dentin are reddish, in the embodiment where only G-PID having an average primary particle diameter in the range of 260 nm to 350 nm is used, compatibility with various color tones of restored teeth is improved and the most. preferable. On the other hand, when only G-PID having a particle size in the range of 150 nm to less than 230 nm is used, as described above, the obtained colored light is bluish, with respect to the cavities formed from enamel to dentin. Is apt to have poor color compatibility with dentin, but is useful for repairing enamel, especially for repairing incisions.

The number of G-PIDs contained in the inorganic particles contained in the structural color-based raw material composition (dispersed in the resin matrix in the structural color-based hybrid resin such as the first composite material) may be one or more. good. The number of G-PIDs contained: a is preferably 1 to 5, particularly preferably 1 to 3, and most preferably 1 or 2.

However, when the inorganic particles contain a plurality of types of G-PID, the average primary particle diameter of each G-PID _m needs to be different from each other by 25 nm or more. That is, each G-PID when the number of G-PIDs contained in the inorganic particles is "a" (for example, "3") is G-PID _m (however, m) in ascending order of the average primary particle diameter. Is 1 when a is 1, and is a natural number from 1 to a when a is 2 or more.) Each G-PID _m (for example, G when a = 3) -The substances constituting the individual particles in PID ₁ , G-PID ₂ and G-PID ₃ ) may be different from each other, but in that case, the average primary particle diameter of each G-PID _m is _dm . , Each dm is 25 nm or more different from each other (for example, when a = 3, | _{d 1} − d ₂ | ≧ 25 nm, | d ₂ − d ₃ | ≧ 25 nm, and of course | d. ₁ -d ₃ | ≧ 25 nm) is required. By satisfying this condition, for example, each G-PID is dispersed in the form of an agglomerate in which a small number of inorganic spherical particles that do not exceed about 20 are aggregated with a very loose binding force. , It seems that it became possible to disperse with a short-range ordered structure that can express the structural color for each G-PID, but as a result, the structure peculiar to each G-PID (according to the average primary particle size). It is possible to develop color. On the other hand, if this condition is not satisfied, the particle size distribution of the entire inorganic spherical particles becomes broad, and the inorganic spherical particles constituting each G-PID are probably interchanged and dispersed, and the number reference It seems that the same phenomenon as when using an aggregate of a single inorganic spherical particle that does not satisfy the condition of particle size distribution occurs, but it becomes difficult to develop the structural color.

When a plurality of G-PIDs are used, the average primary particle diameter _dm of each G-PID _m differs from each other by 30 nm or more, particularly 40 nm or more (that is, the difference between _dm and dm _-1 is 30 nm or more). In particular, it is preferably 40 nm or more). The difference between _dm and dm _-1 is preferably 100 nm or less, particularly preferably 60 nm or less.

When a plurality of G-PIDs are contained in the structural color-based raw material composition and the structural color-based hybrid resin such as the first composite material, each G-PID has an extremely sharp particle size distribution. Moreover, since the average primary particle size has the above-mentioned difference, the particle size distribution of each G-PID is unlikely to overlap, and it is possible to confirm the particle size distribution of each G-PID even if they partially overlap. That is, the particle size distribution of the inorganic particles is such that the particle size distribution of each G-PID has the same number of independent peaks as the number of G-PIDs contained in the range of 100 nm to 1000 nm, and a part of each peak overlaps. Even in this case, the average primary particle size and the number-based particle size distribution of each G-PID can be confirmed by performing waveform processing. Further, the particle size distribution of the inorganic particles contained in the structural color-based hybrid resin such as the first composite material can be confirmed by, for example, image processing an electron micrograph of the inner surface thereof.

(3) Organic-Inorganic Composite Filler At least a part of each of the above-mentioned one or more "same particle size spherical particle group" (G-PID) is combined with one kind of "same particle size spherical particle group" (G-PID). , A resin having a refractive index at 25 ° C. smaller than the refractive index of the inorganic spherical particles constituting the one type of “same particle size spherical particle group” (G-PID) is included, and the above-mentioned one type of “same particle”. Organic-Inorganic Hybrid Filler that does not contain "same particle size spherical particle group" (G-PID) other than "diaspherical particle group" (G-PID), in other words, "single G" -It is preferable to blend it as an "organic-inorganic composite filler containing only PID". Here, the organic-inorganic composite filler is composed of a powder composed of a composite in which the inorganic filler is dispersed in the (organic) resin matrix, or an aggregate in which the primary particles of the inorganic filler are bound by the (organic) resin. Means a filler.

For example, when three types of G-IDPs having different average primary particle diameters, namely G-PID ₁ , G-PID ₂ and G-PID ₃ , are included, all or part of at least one of them is "single G". -It is preferable to blend it as an "organic-inorganic composite filler containing only PID". When all of G-PID ₁ is blended into the structural color-based raw material composition as an organic-inorganic composite filler (composite filler 1) containing only G-PID ₁ , only G-PID ₁ is contained in the composite filler 1. Since the short-range ordered structure that expresses the structural color of G-PID ₁ is realized, the structural color system such as the first composite material obtained by curing the structural color system raw material composition is realized. The structural color of G-PID ₁ is surely expressed even in the hybrid resin. From the viewpoint that such an effect can be expected and the viscosity of the structural color-based raw material composition can be easily adjusted, 10% to 90% of each G-PID, particularly 20% to 80%, and further 30% to 70%. Is preferably blended with an "organic-inorganic composite filler containing only a single G-PID".

When G-PID is blended in a form other than "organic-inorganic composite filler containing only a single G-PID", it is blended in the form of a powder (G-PID itself as an aggregate of inorganic spherical particles). However, it can also be blended as an organic-inorganic composite filler containing a plurality of types of G-PID.

When blended as an organic-inorganic composite filler, the refractive index of the resin constituting the (organic) resin matrix at 25 ° C. is smaller than the refractive index of the inorganic spherical particles contained in the organic-inorganic composite filler. is important. The resin is not particularly limited as long as it satisfies such conditions, but is preferably a cured product of the polymerizable monomer in the raw material composition. At this time, the composition does not have to be exactly the same as that of the polymerizable monomer component of the raw material composition, but the refractive index at 25 ° C. is equivalent to the refractive index of the polymerizable monomer component at 25 ° C. It is preferable to use. Further, when the refractive index of the resin (Resin) at 25 ° C. is n _(R) and the refractive index of the inorganic spherical particles at 25 ° C. is n _(F) , any organic-inorganic composite filler can be used.
n _(R) <n _(F)
It is necessary that the relationship of is established. When the organic-inorganic composite filler contains inorganic spherical particles having different refractive indexes at 25 ° C., this relationship needs to be established for all the inorganic spherical particles. Δn (= n _(F) −n _(R) ), which is the difference between n _(F) and n _(R) , is preferably 0.001 or more and 0.01 or less, and 0.001 or more and 0. It is more preferably .005 or less.

The average particle size of the organic-inorganic composite filler is not particularly limited, but is preferably 2 to 100 μm from the viewpoint of improving the mechanical strength of the cured product and the operability of the curable paste. It is preferably 50 μm, particularly preferably 5 to 30 μm.

The blending amount of the organic-inorganic composite filler in the raw material composition is the total amount contained in the raw material composition in consideration of the blending amount of the same particle size spherical particles: G-PID which is not formed into the organic-inorganic composite filler. The total amount of G-PID (that is, the total amount of inorganic spherical particles) may be determined by converting from the amount of inorganic spherical particles contained in the organic-inorganic composite filler so as to be the above-mentioned amount.

(4) Hyperfine particle group: G-SFP
The ultrafine particle group (G-SFP), which may be contained in the inorganic particles, is a particle aggregate composed of inorganic particles having an average primary particle diameter of less than 100 nm, and is a precursor (cured) of the first composite material. It is blended for the purpose of adjusting the viscosity of the curable composition (a material for obtaining a blank for dental cutting) or for the purpose of adjusting the contrast ratio of the blank for this dental cutting. However, the average primary particle diameter of G-SFP is 25 nm or more smaller than the average primary particle diameter (d ₁ ) of G-PID ₁ , which has the smallest average primary particle diameter among the G-PIDs blended in the inorganic particles. There is a need. If such a condition is not satisfied, the dispersed state of the inorganic spherical particles is adversely affected, and it becomes difficult to develop a specific structural color. The shape of the inorganic particles constituting the G-SFP is not particularly limited, and may be amorphous or spherical. The lower limit of the average primary particle diameter is usually 2 nm.

The average primary particle size of G-SFP is preferably 3 nm or more and 75 nm or less, particularly preferably 5 nm or more and 50 nm or less, because it has little effect on the expression of structural color. Further, for the same reason, it is preferable that it is 30 nm or more, particularly 40 nm or more smaller than the average primary particle diameter (d ₁ ) of G-PID ₁ .

As the material of the inorganic particles constituting the G-SFP, the same materials as those of the inorganic spherical particles can be used without particular limitation. Further, the surface treatment with a silane coupling agent can also be performed in the same manner as the inorganic spherical particles. The preferred embodiment is basically the same as that of the inorganic spherical particles, except for the average primary particle diameter and shape.

5-3. Polymerization Initiator as a Raw Material of Structural Color Raw Material Composition The polymerization initiator used as a raw material of a structural color raw material composition is not particularly limited as long as it has a function of polymerizing and curing a polymerizable monomer. Polymerization methods for curable compositions include reactions with light energy such as ultraviolet rays and visible light (hereinafter referred to as photopolymerization), chemical reactions between peroxides and accelerators, and thermal energy (hereinafter referred to as thermal polymerization). ) Etc., and any method may be used. Photopolymerization and thermal polymerization are preferable because the timing of polymerization can be arbitrarily selected by the energy given from the outside such as light and heat, and the operation is simple. Thermal polymerization is particularly preferred because it can be performed.

Examples of the photopolymerization initiator include benzoin alkyl ethers such as benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether, benzyl ketals such as benzyl dimethyl ketal and benzyl diethyl ketal, benzophenone, 4,4'-dimethylbenzophenone and 4-. Benzophenones such as methacryoxybenzophenone, diacetyl, 2,3-pentadionebenzyl, camphorquinone, 9,10-phenanthraquinone, α-diketones such as 9,10-anthraquinone, 2,4-diethoxythioxane Thioxanson compounds such as son, 2-chlorothioxanson, methylthioxanson, bis- (2,6-dichlorobenzoyl) phenylphosphine oxide, bis- (2,6-dichlorobenzoyl) -2,5-dimethylphenylphosphine oxide , Bis- (2,6-dichlorobenzoyl) -4-propylphenylphosphine oxide, bis- (2,6-dichlorobenzoyl) -1-naphthylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine Bisacylphosphine oxides such as oxide can be used.

A reducing agent is often added to the photopolymerization initiator, and examples thereof include tertiary amines such as 2- (dimethylamino) ethyl methacrylate, ethyl 4-dimethylaminobenzoate, and N-methyldiethanolamine. Examples include aldehydes such as lauryl aldehyde, dimethylaminobenzaldehyde and terephthalaldehyde, and sulfur-containing compounds such as 2-mercaptobenzoxazole, 1-decanthyl, thiosartyl acid and thiobenzoic acid.

Further, there are often examples of using a photoacid generator in addition to the photopolymerization initiator and the reducing compound. Examples of such a photoacid generator include diaryliodonium salt compounds, sulfonium salt compounds, sulfonic acid ester compounds, halomethyl-substituted-S-triazine derivatives, pyridinium salt compounds and the like.

Examples of the thermal polymerization initiator include benzoyl peroxide, p-chlorobenzoyl peroxide, tert-butylperoxy-2-ethylhexanoate, tert-butylperoxydicarbonate, diisopropylperoxydicarbonate and the like. Azo compounds such as peroxides and azobisisobutyronitrile, tributylborane, tributylboran partial oxides, sodium tetraphenylborate, sodium tetrakis (p-floroolophenyl) borate, triethanolamine tetraphenylborate. Examples thereof include boron compounds such as 5-butylbarbituric acid, barbituric acids such as 1-benzyl-5-phenylbarbituric acid, and sulfinates such as sodium benzenesulfinate and sodium p-toluenesulfinate.

These polymerization initiators may be used alone, but two or more of them may be mixed and used. It is also possible to combine a plurality of initiators having different polymerization methods.

The amount of the polymerization initiator to be blended may be selected as an effective amount according to the purpose, but is usually 0.01 to 10 parts by mass with respect to 100 parts by mass of the polymerizable monomer, more preferably 0.1. It is used in a proportion of up to 5 parts by mass.

When the thermal polymerization initiator is used, the polymerization temperature is preferably 60 to 200 ° C, more preferably 70 to 150 ° C, still more preferably 80 to 130 ° C. When the polymerization is carried out at a temperature of 60 ° C. or lower, the polymerization reaction becomes insufficient, the strength of the blank for dental cutting is weakened, and cracks occur. On the other hand, when the polymerization is carried out at a temperature of 200 ° C. or higher, the structural color-based hybrid resin is exposed to a high temperature during production, so that the resin component is discolored, and the color tone compatibility with the natural tooth, which is the effect of the present invention, is obtained. It becomes difficult.

5-4. Other Additives Used as Raw Materials for Structural Color Raw Material Compositions The structural color raw material composition may contain other additives such as polymerization inhibitors and UV absorbers as long as the effects are not impaired. can.

The cured product of the structural color-based raw material composition is a structural color-based hybrid resin including the first composite material, and as described above, it develops a specific structural color without using a coloring substance such as a pigment. .. Therefore, it is not particularly necessary to add a coloring substance such as a dye or a pigment that may change color with time to the structural color hybrid resin, and the coloring substance should not be contained from the viewpoint of preventing discoloration and transparency. Is preferable. However, the blending of these coloring substances itself is not excluded, and the blending can be performed as long as the effect of the specific structural color is not impaired. Although it depends on the amount of inorganic particles and the like contained in the structural color-based raw material composition that is the raw material of the first composite material, the total mass of the structural color-based raw material composition (which is also the total mass of the first composite material) is used as a reference. The (allowable) amount of the coloring substance to be blended is usually 100% by mass or less, preferably 50% by mass or less. However, with respect to the structural color-based raw material composition that is the raw material of the second composite material and the composite material that becomes the second layer side additional layer formed as needed, the effect of coloring is greater than the effect of the specific structural color. Since it is prioritized, it is necessary to add the coloring substance so that the color difference from the first composite material is within a predetermined range as described later.

5-5. Method for preparing raw material composition The raw material composition can be prepared by kneading and defoaming a predetermined amount of each of the above components. In order to surely satisfy the conditions (I) and (II) of the dispersed state, it is preferable to make adjustments as follows. That is, as for the kneading method, it is possible to knead using a kneading device such as a planetary motion type stirrer because the above dispersion conditions can be satisfied in a short time and scale-up production is easy. preferable. Further, as the defoaming treatment, it is preferable to adopt a method of defoaming under reduced pressure because bubbles can be removed from the highly viscous composition in a short time.

In the method, in the kneading and defoaming treatment, the dispersed state of the inorganic particles (b) in the cured product obtained by curing the kneaded product satisfies the conditions (I) and (II). It is necessary to adopt the kneading and defoaming treatment conditions that have been confirmed to be used.

For such conditions, (1) a plurality of kneading conditions and defoaming treatment conditions are changed in advance by using a curable composition having the same or substantially the same composition as the raw material composition actually produced. The conditions (I) and (II) are satisfied by examining the radial radial distribution function: g (r) in the cured product of the curable composition prepared under each condition. It is preferable to determine and adopt the same conditions as the determined conditions. Since the desired first polymerization curable composition can be reliably produced only by setting predetermined kneading conditions, the same (same composition and same amount) first polymerization curable composition can be produced each time. It is possible to improve work efficiency in that it is not necessary to change the conditions each time during manufacturing and excessive kneading (kneading for an unnecessarily long time) can be prevented.

6. Non-structural color-based hybrid resin and its raw materials, etc. The non-structural color-based hybrid resin is a specific structural color because it contains a large amount of hybrid resin or pigment that does not satisfy at least one of the above conditions (a) to (d). It is a hybrid resin whose expression can no longer be visually confirmed, and it is used as these composite materials when the second composite material and the composite material to be the second layer side additional layer added as needed do not develop the structural color. To.

As described above, the second composite material has a different color tone from the first composite material, and the color difference needs to be in a specific range. Further, the contrast ratio of the second composite material: CR2 is preferably 0.50 to 0.65. Since the first composite material obtains the effect of a specific structural color, it is not usually colored by adding a coloring material such as a dye or a pigment. Therefore, the second composite material and the raw material composition as a raw material thereof are usually colored. The substance is mixed. This point also applies to the composite material serving as the additional layer on the second layer side and the raw material composition thereof, which are added as needed.

That is, in the non-structural color-based hybrid resin which is the second composite material and the composite material which becomes the second layer side additional layer added as needed, the inorganic particles are dispersed in the resin matrix and the first composite is formed. A composite material to which a coloring material such as a dye or a pigment is added so that the color difference from the material is within a specific range, and a polymerization curable composition containing a polymerizable monomer, an inorganic particle, a polymerization initiator and a coloring material. It is obtained by curing a substance (hereinafter, also referred to as "non-structural color-based raw material composition"). The non-structural color-based raw material composition may be a structural color-based raw material composition to which a coloring material is added (in an amount such that a specific structural color cannot be visually confirmed), and is a polymerizable monomer and a polymerization initiator. The same as the structural color-based raw material composition can be used. The inorganic particles are not particularly limited as in the structural color-based raw material composition, and those that can be used in the conventional resin-based blank for dental cutting can be used without particular limitation. The total amount of the inorganic particles to be blended is usually 100 to 900 parts by mass, preferably 150 to 700 parts by mass, based on 100 parts by mass of the polymerizable monomer. The amount of the coloring substance contained in the non-structural color-based raw material composition is usually 500 to 7000 mass based on the total mass of the non-structural color-based raw material composition (which is also the total mass of the composite material which is the cured product thereof). It is ppm, preferably 600 to 6500 mass ppm. Further, it may contain an ultrafine particle group (G-SFP) for adjusting the color tone and contrast ratio of the cured product, and other additives such as a polymerization inhibitor and an ultraviolet absorber.

In the blank of the present invention, the second composite material and the non-structural color-based hybrid resin to be the second layer side additional layer added as needed are materials constituting the vicinity of the cervical region of the dental prosthesis. In addition, there are large individual differences in the color tone of the cervical part of the tooth, and it is necessary to prepare a color tone that suits each individual patient. By adding a coloring substance, such a requirement can be met. Is possible.

The coloring substance (coloring agent) may be a pigment or a dye. Typical pigments are inorganic pigments, and such inorganic pigments include titanium oxide, zinc oxide, zinc oxide, zinc sulfide, aluminum silicate, calcium silicate, carbon black, iron oxide, and copper chromate black. Examples include zinc oxide green, chrome green, violet, chrome yellow, lead chromate, lead molybdate, cadmium titanate, nickel titanium yellow, ultramarine blue, cobalt blue, bismus vanadate, cadmium yellow, cadmium red and the like. can. In addition, in the present invention, the inorganic pigment also corresponds to an inorganic filler. Further, organic pigments such as monoazo pigments, diazo pigments, diazo condensed pigments, perylene pigments and anthraquinone pigments can also be used. The dyes include red dyes such as KAYASET RED G (Nippon Kayaku) and KAYASET REDB (Nippon Kayaku); yellow dyes such as KAYASET Yellow 2G and KAYASET Yellow GN; Blue dyes such as; Considering the color stability in the oral cavity, it is preferable to use a water-insoluble pigment rather than a water-soluble dye.

7. Method for Manufacturing a Blank of the Present Invention The blank of the present invention can be manufactured by appropriately processing a laminated body of a hybrid resin having the laminated structure to form a machined portion.

The above-mentioned hybrid resin laminate can be suitably produced by cast polymerization using a curable raw material composition as a raw material for the hybrid resin (complex) constituting each layer. Here, the casting polymerization means that a molding mold having a predetermined shape is filled with the polymerization curable composition and then polymerized and cured. The volume of the molding die may be appropriately selected according to the desired shape. Similarly, the shape of the molding die may be a prismatic shape, a columnar shape, a square plate shape, a disc shape, or any other irregular shape, and is not particularly limited. At the time of polymerization, if necessary, the pressure may be applied with an inert gas such as nitrogen. A molding die having the same or substantially the same shape as the part to be machined is prepared, and the curable raw material composition to be each layer is sequentially filled therein so as to have a predetermined thickness, and then polymerized and cured. The obtained bulk body (laminated body of hybrid resin) may be used as it is as a part to be machined, or it may be filled in a mold having a larger size to manufacture a bulk body, which may be punched or cut. It may be used as a machined portion. A known technique can be used for filling, and the filling method is not particularly limited. For example, the molding die can be filled by injection, extrusion, pressing, or the like.

As the material of the molding die, metal, ceramics, resin or the like can be used depending on the purpose, and it is preferable to use a material having higher heat resistance than the polymerization temperature to be carried out. Examples of the material of the mold include SUS, high-speed tool steel, aluminum alloy, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polystyrene (PS) and the like.

Further, the obtained bulk body can be subjected to post-processes such as heat treatment, polishing, cutting, attachment of a holder, and printing, if necessary. Further, if necessary, a holding pin for fixing the dental cutting blank to the cutting machine may be joined. The shape of the holding pin is not particularly limited as long as it can fix the dental cutting blank to the cutting machine, and may not be provided depending on the shape of the dental cutting blank and the requirements of the processing machine. .. Examples of the material of the holding pin include stainless steel, brass, and aluminum. The method of fixing the holding pin to the machined portion (blank body for dental cutting) is not limited to adhesion, and may be a method such as fitting or screwing. The bonding method is also not particularly limited, and various commercially available adhesives such as isocyanate-based, epoxy-based, urethane-based, silicone-based, and acrylic-based can be used.

Next, the multilayer mill blank of the present invention will be specifically described with reference to Examples. In each Example and Comparative Example described later, various structural color-based raw material compositions and non-structural color-based raw material compositions are prepared, and the obtained compositions and their cured products are evaluated and these compositions are used. By laminating objects in a predetermined combination and then curing them, a hybrid resin laminate to be a machined portion of a blank for dental cutting is obtained and evaluated.

1. 1. About the raw materials of the structural color-based raw material composition and the non-structural color-based raw material composition The raw materials of the structural color-based raw material composition and the non-structural color-based raw material composition used in Examples and Comparative Examples, and their physical properties are described below. do.

1-1. Polymerizable Monomer Component As the polymerizable monomer component in the structural color-based raw material composition and the non-structural color-based raw material composition, a polymerizable monomer mixture having the composition shown in Table 1: M1 was used. The abbreviations in the polymerizable monomer column of Table 1 represent the compounds shown below, and the numbers in parentheses after the abbreviations represent the parts by mass used.
-UDM: 1,6-bis (methacrylethyloxycarbonylamino) trimethylhexane-3G: triethylene glycol dimethacrylate In addition, the viscosity of M1 and the refractive index of M1 (before curing) and its cured product are measured as follows. bottom. The results are also shown in Table 1. That is, the viscosity was measured in a constant temperature room at 25 ° C. using an E-type viscometer (Tokyo Seiki: VISCONIC ELD). The refractive index of M1 (before curing) and the cured product thereof was measured in a constant temperature room at 25 ° C. using an Abbe refractive index meter (manufactured by Atago Co., Ltd.). At this time, the cured product sample contains 0.2% by mass of camphorquinone (CQ) (as a photopolymerization initiator) per 100 parts by mass of the polymerizable monomer, and ethyl (DMBE) p-N, N-dimethylaminobenzoate. 0.3% by mass and 0.15% by mass of hydroquinone monomethyl ether (HQME) were added and mixed uniformly, and the mixture was placed in a mold having a through hole of 7 mmφ × 0.5 mm, and polyester films were pressure-welded on both sides. Later, it was prepared by irradiating with light for 30 seconds using a halogen type dental light irradiator (Demethron LC, manufactured by Cybron) having a light amount of 500 mW / cm ² to cure the mixture, and then removing the light from the mold. When setting the cured sample in the Abbe refractive index meter, bromonaphthalene, which is a solvent that does not dissolve the sample and has a higher refractive index than the sample, is used as the sample for the purpose of bringing the cured sample into close contact with the measurement surface. Dropped.

1-2. Spherical particle group with the same particle size: G-PID
As G-PID, G-PID1 and G-PID2 shown in Table 2 were used. G-PID1 and G-PID2 were prepared in the same manner as the method disclosed in Patent Document 5 (sol-gel method), and both were surface-treated with γ-methacryloyloxypropyltrimethoxysilane. Further, for G-PID1 and G-PID2, as in the method described in the examples of Patent Document 5, the average primary particle size and the particle ratio within ± 5% [in the number-based particle size distribution] are as follows. The ratio (%) of the number of particles existing in the range of 5% before and after the average primary particle size to the total number of particles], the average uniformity and the refractive index were measured. The results are shown in Table 2. As shown in Table 2, it can be said that G-PID1 and G-PID2 are both spherical particles having the same particle size and satisfy the above condition (a).

(1) Average primary particle size Take a picture of the powder with a scanning electron microscope ("XL-30S" manufactured by Philips) at a magnification of 5000 to 100,000 times, and image analysis software ("IP-1000PC", trade name; Using Asahi Kasei Engineering Co., Ltd.), the photographed image is processed, and the number of particles (30 or more) and the primary particle diameter (maximum diameter) observed in the unit field of view of the photograph are measured and used as the measured value. Based on this (the value obtained by dividing the total by the number of particles), the number average primary particle diameter was calculated.

(2) ± 5% inner particle ratio Of all the particles (30 or more) in the unit field of view in the above photograph, the primary particle diameter (maximum diameter) outside the particle diameter range of 5% before and after the average primary particle diameter obtained above. ) Is measured, and the value is subtracted from the total number of particles to obtain the number of particles within the particle size range of 5% before and after the average primary particle size in the unit field of view of the above photograph. Calculated according to.

± 5% particle ratio (%) = [(number of particles within the particle size range of 5% before and after the average primary particle size in the unit field of scanning electron micrograph) / (within the unit field of scanning electron micrograph) Total number of particles in)] × 100

(3) Average uniformity Take a picture of the powder with a scanning electron microscope, and the number (n: 30 or more) of particles of the same particle size spherical particle group (G-PID) observed in the unit field of view of the picture. ), The ratio (Bi / Li) of the maximum diameter of the particles is the major axis (Li) and the diameter in the direction orthogonal to the major axis is the minor axis (Bi), and the sum of the ratios divided by the number of particles is averaged. The degree of uniformity was set.

(4) Refractive index Measured by the immersion method using an Abbe refractive index meter (manufactured by Atago). That is, in a constant temperature room at 25 ° C., the same particle size spherical particle group (G-PID) is dispersed in 50 ml of anhydrous toluene in a 100 ml sample bottle. While stirring this dispersion with a stirrer, 1-bromotoluene is added dropwise little by little, the refractive index of the dispersion at the time when the dispersion becomes the most transparent is measured, and the obtained value is the same particle size spherical particle group ( It was defined as the refractive index of G-PID).

1-3. Organic-Inorganic Composite Filler (CF)
The organic-inorganic composite filler (CF) was also prepared as follows using G-PID2 shown in Table 2 in the same manner as in the examples of Patent Document 5. That is, first, a dispersion liquid in which G-PID 2: 100 g was dispersed in 200 g of water was obtained using a circulation type crusher SC mill (manufactured by Nippon Coke Industries, Ltd.). Next, a separately prepared mixed solution (pH 4) of γ-methacryloyloxypropyltrimethoxysilane: 4 g, acetic acid: 0.003 g and water: 80 g was added to the above dispersion, mixed until uniform, and then the dispersion was added. While being lightly mixed, it was supplied onto a disk rotating at high speed, granulated by a spray drying method, and then vacuum dried at 60 ° C. to obtain a substantially spherical aggregate. Then, 1:10 g of the polymerizable monomer component M, 0.025 g of azobisisobutyronitrile (AIBN) as a thermal polymerization initiator, and 5.0 g of methanol as an organic solvent were mixed into a polymerizable monomer solution. The above-mentioned polymerizable monomer component is polymerized and cured by immersing 50 g of the above-mentioned aggregate, stirring sufficiently, removing the organic solvent, and then heating under the conditions of a reduced pressure of 10 hectopascals and 100 ° C. for 1 hour. Obtained an organic-inorganic composite filler (CF) having a substantially spherical shape and an average particle size of 12 μm.

1-4. Hyperfine particles (G-SFP)
As G-SFP, Leorosea QS-102 (average primary particle diameter 12 nm, manufactured by Tokuyama Corporation) was used.

1-5. Polymerization Initiator A thermal polymerization initiator composed of benzoyl peroxide (BPO) was used.

1-6. Pigment ・ Red pigment (Pigment Red 166)
-Yellow pigment (Pigment Yellow 95)
-Blue pigment (Pigment Blue 60).

2. 2. Preparation of structural color-based raw material composition and non-structural color-based raw material composition and evaluation of cured product 2-1. Preparation of Structural Color Raw Material Compositions (P1 to P6) Structural color raw material composition: P1 was prepared as shown below. That is, after mixing 100 parts by mass of M1: 100 parts by mass of BPO and 1.0 part by mass of BPO, the mass ratio of G-PID1 and G-SFP is G-PID1: G-SFP = 95: 5, and the structural color system. Add so that the inorganic filling ratio defined by the ratio of the total mass of the inorganic particles to the total mass of the raw material composition is 72% by mass, and mix until uniform using a planetary mixer to form a paste and structure. Color-based raw material composition: P1 was prepared.

Further, structural color-based raw material compositions: P2 to P6 were prepared by the same method as above except that the inorganic filling factor was set to the inorganic filling factor shown in Table 3.

The refractive index of the cured product of M1: n _(MX) is 1.509, and the refractive index of G-PID1 is n (G-PID1) = 1.515, respectively, which is larger than n _(MX) . Therefore, the above condition (c) is satisfied. Therefore, the hybrid resin composed of these structural color-based raw material compositions: cured products of P1 to P6 all satisfy the above conditions (a) to (c) {G-PID blended in P1 to P6 is It is said that there is only one type and the above condition (b) is also satisfied. }.

2-2. Preparation of non-structural color-based raw material composition (L1 to L6) After mixing M1: 100 parts by mass and BPO 1.0 part by mass, G-PID2: 50% by mass and CF (organic-inorganic composite filler): 50% by mass. % Of the mixture was added so that the inorganic filling ratio was 76%, and various pigments were added in the addition amounts shown in Table 4, except that the composition of the non-structural color-based raw material was the same as in the preparation of P1. Object: L1 to L6 were prepared.

2-3. Evaluation of cured product of each raw material composition 2-3-1. Confirmation that the cured product of the structural color-based raw material compositions (P1 to P6) is a structural color-based hybrid resin, according to the method described in Patent Document 5, by the methods shown in the following (1) to (3). For the cured product of each structural color-based raw material composition (P1 to P6), visual evaluation of colored light, measurement of peak wavelength of colored light, and evaluation of dynamic diameter distribution function of inorganic spherical particles were performed. The results are shown in Table 5.

(1) Visual evaluation method of colored light After vacuum defoaming the structural color-based raw material compositions (P1 to P6), filling them in a mold of 10 mm × 12 mm × 14 mm, filling them, and smoothing the upper surface, Using a heat-pressurized polymerizer, heat-pressurization polymerization was performed under the conditions of a pressure of 0.4 MPa, 100 ° C., and 12 hours under nitrogen pressurization. A solid sample having a size of 1 mm × 12 mm × 14 mm was cut out from the taken-out cured product, and a solid sample for measuring colored light prepared by gloss polishing was prepared. A solid sample for measuring colored light was placed so as to be perpendicular to the adhesive surface of a black tape (carbon tape) having a size of about 10 mm square, and the color tone of the colored light was visually evaluated.

(2) Method for measuring peak wavelength of colored light With respect to a solid sample for colored light measurement to which a black tape prepared in the same manner as in (1) is attached, a spectrophotometer (manufactured by Tokyo Denshoku Co., Ltd., "TC-1800MKII", halogen lamp: 12V100W) , The measurement wavelength range (380 to 780 nm) was used to measure the spectral reflectance with a black background, and the maximum point of the reflectance was defined as the wavelength of the colored light.

(3) Evaluation method of radial distribution function of inorganic spherical particles A cured product was prepared by the same method as in (1) except that the structural color-based raw material compositions (P1 to P6) were filled in a mold of 5 mmφ × 10 mm. The radial distribution function was obtained and evaluated by observing the dispersed state of the spherical particles in the cured product with a scanning electron microscope (“XL-30S” manufactured by Phillips). Specifically, an ion milling apparatus (“IM4000” manufactured by Hitachi, Ltd.) was used to perform cross-sectional milling of the cured product under the conditions of 2 kV for 20 minutes to obtain an observation plane. A scanning electron microscope is used to acquire a microscope image of a region containing 1000 spherical particles in the plane of the observation surface, and the obtained scanning electron microscope image is used as an image analysis software (“Simplifier Digitizer ver3.2””. The analysis was performed by free software), and the coordinates of the spherical particles in the above region were obtained. Select one coordinate of any spherical particle from the obtained coordinate data, draw a circle with a radius r containing at least 200 or more spherical particles around the selected spherical particle, and include it in the circle. The number of spherical particles was calculated, and the average particle density <ρ> (unit: pieces / cm ² ) was calculated. dr is a value of about r _0/100 to r _0/10 (r ₀ indicates the average particle diameter of spherical particles), and is between a circle at a distance r and a circle at a distance r + dr from the central spherical particle. The number of particles dn contained in the region and the area da of the region (however, da = 2πr · dr) were determined. Using the values of <ρ>, dn, and da thus obtained,
Equation: g (r) = {1 / <ρ>} × {dn / da}
The radial distribution function g (r) defined in is obtained. Then, a graph showing the relationship between the radial distribution function and r / r ₀ (r indicates an arbitrary distance from the center of the circle, and r ₀ indicates the average particle diameter of spherical particles) is created, and the radial diameter is generated. Regarding the conditions 1 and 2 of the distribution function, those satisfying the conditions were evaluated as "S", and those not satisfying the conditions were evaluated as "N".

As shown in Table 5, it was confirmed that in the cured product of the structural color-based raw material compositions (P1 to P6), the dispersed state of the spherical inorganic particles satisfied the above condition (d) and developed a specific structural color. ..

2-3-2. Lightness of each raw material composition is L ^* , hue is a ^* and saturation b ^* , and contrast ratio (CR) evaluation. Structural color raw material compositions (P1 to P6) and non-structural color raw material compositions (L1 to). For the cured product of L6), L ^* , a ^* and b ^* and CR were measured by the methods shown in (4) and (5) below. The results are shown in Table 6.

(4) Measurement of brightness L ^* , hue a ^* and saturation b ^* Each raw material composition was vacuum defoamed, filled in a mold of 10 mm × 12 mm × 14 mm, filled, and the upper surface was smoothed. Then, using a heat-pressurized polymerizer, heat-pressurization polymerization was performed under the conditions of a pressure of 0.4 MPa, 100 ° C., and 12 hours under nitrogen pressurization. A solid sample having a size of 14 mm × 12 mm × 1 mm was cut out from the removed cured product to prepare a solid sample for color difference measurement. This solid sample is measured by the reflected light 0 ° d method (JIS Z8722) using a spectrophotometer (manufactured by Tokyo Denshoku Co., Ltd., "TC-1800MKII", halogen lamp: 12V100W, measurement wavelength range 380 to 780 nm). Measure the spectral reflectance of the background color black (light shielded state) and the spectral reflectance of the background color white (light shielded by overlaying a standard white plate on the cured body) at an area of 5 mmφ, and measure the L ^* value and a ^* value. And b ^* values were calculated.

(5) Measurement of contrast ratio (CR) Contrast ratio CR = Y _B / Y based on Y _B , which is the Y value in the background color black, and Y _W , which is the Y value in the background color white, using the above color difference meter for the above sample. _W was calculated.

3. 3. Examples and Comparative Examples The above P1 to 6 and L1 to 6 pastes are used in the combinations shown in Table 7, and the hybrid resin layer and the second layer are made of a cured product of the raw material composition for the first layer as follows. A hybrid resin laminated body having a two-layer structure in which a hybrid resin layer made of a cured product of the raw material composition of No. 1 was joined to have the same layer thickness was produced.

That is, after filling the raw material composition for the first layer in the mold to half the height (5 mm) of the mold and allowing it to stand until the surface becomes flat, care not to disturb the interface. Except for filling the raw material composition for two layers so as to fill the inside of the mold, curing is performed in the same manner as for preparing the samples for L ^* , a ^* and b ^* measurements to prepare the machined portion to be machined. bottom.

The laminated interface of the obtained machined part to be machined is evaluated, and a holding pin is adhered to the machined part to be machined to form a resin blank for dental cutting, and a dental restoration (crown) produced using this. ) Laminated interface state and natural tooth approximation were evaluated. The specific evaluation method is shown below. The evaluation results are shown in Table 7 together with the color difference between the first layer and the second layer: ΔE ^* and the contrast ratio difference: ΔCR (= CR2-CR1).

(1) Evaluation of the laminated interface It was visually observed to confirm whether the laminated interface could be seen. The evaluation criteria are shown below.
5: The laminated interface between the upper layer and the lower layer is completely invisible.
4: The laminated interface between the upper layer and the lower layer cannot be seen.
3: The laminated interface between the upper layer and the lower layer is almost invisible.
2: The laminated interface between the upper layer and the lower layer is slightly visible.
1: The laminated interface between the upper layer and the lower layer is clearly visible.

(2) Evaluation of laminated interface of simulated dental restoration After making a dental restoration (restoration) by cutting the crown on the upper right with a cutting machine (Roland, "DWX-50") , Estesem II (adhesive resin cement manufactured by Tokuyama Dental Co., Ltd.) was used to adhere to the resin abutment tooth (equivalent to A3 color), polished, and simulated restoration was performed. The state of the laminated interface after restoration was visually confirmed. The evaluation criteria are shown below.
5: The laminated interface between the upper layer and the lower layer is not visible at all, and the color tone is natural.
4: The laminated interface between the upper layer and the lower layer is almost invisible, and the color tone is natural.
3: It is difficult to see the laminated interface between the upper layer and the lower layer.
2: The laminated interface between the upper layer and the lower layer can be seen faintly.
1: The laminated interface between the upper layer and the lower layer is clearly visible, and the color tone is unnatural.

(3) Evaluation of closeness to natural teeth of simulated dental restorations It was visually confirmed whether the color tone of the simulated restorations prepared in the same manner as in (2) from the cervical part to the incisal part was close to that of natural teeth. .. The evaluation criteria are shown below.
5: Natural color tone, such as natural teeth.
4: The color tone is similar to that of natural teeth.
3: The color tone is a little similar to natural teeth.
2: The color tone is not very similar to that of natural teeth and feels a little strange.
1: An unnatural color tone that does not resemble natural teeth at all.

As shown in Table 7, "Comparative Example 1" which is a single-layer structural color resin blank (of P1 cured product) and Comparative Example 2 which is a single-layer non-structural color resin blank (of L1 cured product) ""Natural tooth closeness evaluation" is "1". That is, in Comparative Example 1, although the color tone in which the cervical portion was dark and the incisal portion was thin and transparent was expressed, the color of the crown was white, so that the evaluation was low in the visual evaluation of approximation to natural teeth. Further, in Comparative Example 2, since the entire crown was a non-structural color system, the color tone in which the cervical portion was dark and the incisal portion was light was not reproduced, and the approximation to the natural tooth was low in the visual evaluation. On the other hand, the "natural tooth closeness evaluations" of Examples 1 to 11 are all highly evaluated as compared with the evaluations of Comparative Example 1 and Comparative Example 2, although the degree is different. Among them, ΔE ^* , CR1, CR2 and ΔCR are all in a suitable range (ΔE ^* = 2 to 20, CR1 = 0.28 to 0.43, CR1 = 0.55 to 0.63, ΔCR = 0.12 to 0). For Examples 1, 2, 8 to 10 of .27), "4" in all the evaluations of "evaluation of laminated interface", "evaluation of laminated interface of simulated dental restoration" and "evaluation of natural tooth approximation". The evaluation is higher than that.

Claims (4)

In a resin-based blank for dental cutting, which has a processed portion made of a composite material in which inorganic particles are dispersed in a resin matrix.
The composite material has a laminated structure in which the first layer and the second layer are joined.
The first layer is made of a first composite material which is a composite material that develops a structural color of a predetermined color tone regardless of the incident angle of light.
The second layer is made of a second composite material made of a composite material having a color tone different from that of the first composite material.
The color tone of the composite material having a single color tone is shown by the L ^* value, a ^* value and b ^* value obtained by measuring the sample with a thickness of 1.0 ± 0.1 mm with a fair background using a spectrophotometer. When you do
The following formula ΔE ^* = {(L1 ^* -L2 ^* ) ² + (a1 ^* -a2 ^* ) ² + (b1 ^* -), which is an index of the difference between the color tone of the first composite material and the color tone of the second composite material. b2 ^* } ^1/2
(In the above formula, L1 ^* , a1 ^* and b1 ^* are the L ^* value, a ^* value and b ^* value in the first composite material, and L2 ^* , a2 ^* and b2 ^* are the second composite material. L ^* value, a ^* value and b ^* value in.)
Color difference defined by: ΔE ^* is 2 to 30,
A resin-based blank for laminated dental cutting that is characterized by this. The resin-based blank for laminated dental cutting according to claim 1, wherein the first composite material satisfies all the conditions shown in the following (a) to (d).
(A) The inorganic particles are composed of aggregates of inorganic spherical particles having a predetermined average primary particle diameter in the range of 100 nm to 1000 nm, and 90% or more of the total number of particles in the number-based particle size distribution of the aggregates. It contains one or more spherical particle groups (G-PIDs) of the same particle size existing in the range of 5% before and after the predetermined average primary particle diameter.
(B) Let a be the number of the spherical particles having the same particle size contained in the inorganic particles, and G-PIDm (where m is a) for each group of spherical particles having the same particle size in ascending order of the average primary particle diameter. When is 1, it is 1, and when a is 2 or more, it is a natural number from 1 to a.) When a is 2 or more, the average primary particle diameter of each G-PIDm is They differ from each other by 25 nm or more.
(C) The refractive index of the resin matrix with respect to light having a wavelength of 589 nm at 25 ° C. is n (MX), and the refractive index of the inorganic spherical particles constituting each G-PIDm with respect to light having a wavelength of 589 nm at 25 ° C. is n (G-). When PIDm) is set, for any n (G-PIDm),
n (MX) <n (G-PIDm)
The relationship is established.
(D) In the first composite material, it is a function representing the probability that another inorganic spherical particle exists at a point r away from the center of the arbitrary inorganic spherical particle, and is an observation plane of the inner surface of the composite material. The average particle density of the inorganic spherical particles in the observation plane determined based on the scanning electron microscope image: <ρ>, and a circle having a distance r from any inorganic spherical particles in the observation plane. The following equation (1) is based on the number of inorganic spherical particles existing in the region between the circles having a distance r + dr: dn, and the area of the region: da (where da = 2πr · dr).
g (r) = {1 / <ρ>} × {dn / da} ... (1)
Function defined in: When g (r) is a radial distribution function, the inorganic spherical particles constituting the all-same particle size spherical particle group (G-PID) in the composite material are the following condition 1 and the following. It is dispersed in the matrix material so as to have a short-range ordered structure that satisfies the condition 2.
[Condition 1]: The standard is obtained by dividing the distance from the center of any inorganic spherical particles dispersed in the composite material by the average particle diameter of all the inorganic spherical particles dispersed in the composite material: _r0 . With the converted non-dimensional number (r / r ₀ ) as the x-axis and the radial distribution function: g (r) as the y-axis, the r / r ₀ and the g (r) corresponding to r at that time In the radial distribution function graph showing the relationship, among the peaks appearing in the radial distribution function graph, the closest particle distance: r ₁ defined as r corresponding to the peak top of the peak closest to the origin is described above. The average particle size of all the inorganic spherical particles dispersed in the composite material: a value of 1 times or more and 2 times or less of _r0 .
[Condition 2]: Among the peaks appearing in the radial distribution function graph, when r corresponding to the peak top of the peak second closest to the origin is the distance between the next closest particles: r ₂ , the closest particles The minimum value of the radial distribution function: g (r) between the distance: r ₁ and the distance between the next adjacent particles: r ₂ is a value of 0.56 or more and 1.10 or less. The total blending amount of the pigment and the dye in the first composite material is 100% by mass or less with respect to the total mass of the first composite material, and the total blending amount of the pigment and the dye in the second composite material is the second composite. 500-7000 mass ppm with respect to the total mass of the material,
The resin-based blank for laminated dental cutting according to claim 1 or 2. The transparency of the composite material is obtained when the color difference is measured with a spectrophotometer for a sample with a thickness of 1.0 ± 0.1 mm. Y value on a white background: Y value on a black background with respect to Y _W : When the value determined as Y _B / ratio: Y _B / Y _W is expressed using the contrast ratio: CR as an index,
The contrast ratio of the first composite material: CR1 is 0.28 to 0.46, and the contrast ratio of the second composite material: CR2 is 0.50 to 0.65.
The resin-based blank for laminated dental cutting according to any one of claims 1 to 3.