RU2783641C2 - Resin-based block for milling processing in dentistry - Google Patents

Abstract

FIELD: dentistry.

SUBSTANCE: group of inventions relates to a resin block for milling processing in dentistry for obtainment of dentures and a method for its production. The resin block for milling processing in dentistry contains a resinous matrix (A), a spherical filler (B), an average particle size of which is in the range from 240 nm to 500 nm, and which is such that, with a thickness of 10 mm and when measured with a colorimeter, lightness (V) is less than 5.0, and saturation (C) is less than 2.0, wherein these values are measured in the Mansell color system for colored light on a black background and on a white background, (C) inorganic particles with an average particle size of less than 100 nm, and which are such that, with a thickness of 1 mm and when measured with a colorimeter, lightness (V) is less than 5.0, and saturation (C) is 0.05 or more, wherein these values are measured in the Mansell color system for colored light on a black background, but on a white background, lightness (V) is 6.0 or more, and saturation (C) is less than 2.0, wherein these values are measured in the Mansell chromaticity color system for colored light. In this case, the amount of the spherical filler (B) is from 10 parts by weight to 1500 parts by weight per 100 parts by weight of the resinous matrix (A), the amount of inorganic particles (C) is from 0.1 to 50 parts by weight per 100 parts by weight of the resinous matrix (A), in which 90% or more of individual particles composing the spherical filler (B) are in the range of the specified average particle size ± 5%, and each of the resinous matrix (A) and the spherical filler (B) is selected in such a way that to meet the requirement (X1) expressed by the following inequality (1): nP<nF (1), where nP is a refractive index of the resinous matrix (A) at 25°C, and nF is a refractive index of the spherical filler (B) at 25°C. A method for the production of a resin block is also disclosed.

EFFECT: group of inventions provides a resin block for milling processing in dentistry, using which the restoration of teeth is carried out in such a way that the appearance of dentures obtained from the block, without the use of pigment or dye, is consistent with a color tone of patient’s teeth, while the color tone compatibility between dentures obtained from the block and patient’s teeth is maintained for a long time.

5 cl, 6 tbl, 18 ex

Description

The field of technology to which the invention belongs

The present invention relates to a dental milling resin block for producing dental prostheses that is simple and excellent in aesthetic appearance.

State of the art

In dental treatment, as a method for producing dental prostheses such as an inlay, an onlay, a crown, a bridge, and an implant top, a milling method is known that uses a dental computer-aided design and programming system (CAM system). CAD/CAM). The CAD/CAM system uses a computer to design dentures based on 3D data and uses a milling machine to produce dentures. Various materials such as glass ceramics, zirconia, titanium and resins are used as milling material. As a dental resin material for milling, cured block or disc-shaped products are provided, which are obtained by curing a curable composition containing an inorganic filler such as silicon dioxide, a polymerizable monomer such as methacrylate resin, and a polymerization initiator. Dental resin milling materials have attracted attention due to their high workability, esthetics, and strength, and various materials have been proposed.

In the treatment of teeth, it is required to give them an appearance that is as close as possible to the color tone of the patient's teeth, however, in order to meet this aesthetic requirement, in many cases it is not always enough to obtain a block body consisting of a single component by milling, and still many block bodies have been proposed for milling, with each body consisting of many hue layers.

For example, PTL 1 describes an invention related to a block of resin for milling in dentistry, which is composed of a plurality of layers having different color tones and transparency (contrast ratio), that is, specifically indicating that when two or three layers are made in a block in order to match the specific relationship between hue and transparency (contrast ratio), the resulting block may have the same ivory and enamel color as the patient's teeth, and the boundary layer between the layer components may not be visible.

Document PTL 2 describes an invention relating to a curable composition used as a dental filler and restorative material that has excellent compatibility with the color tone of a patient's teeth without the use of pigment or dye; specifically describes a dental filler and restorative material that uses a spherical filler having a particle size within a given range, and which forms a cured product, the appearance of which is in harmony with the patient's teeth, and the specified harmony with the patient's teeth is maintained for a long time. However, in the case of treating a large cavity, which requires the installation of an inlay or the like in the portion of the molar tooth in which bite pressure is applied, there is a problem with said curable composition in terms of mechanical strength.

Citation list

Patent Literature

PTL 1: Japanese Patent Application JP 2017-105764 A

PTL 2: WO2017/069274

Disclosure of invention

Technical problem

The above document PTL 1 refers to the color tone and layer structure of the block used in the dental CAD/CAM system. However, since there are individual differences in the color tone of the patient's teeth, it is necessary in the prior art to produce a block consisting of a plurality of layers having different color tones and transparency (contrast ratio), and furthermore, in order to accommodate the difference in color tone due to individual differences , it is necessary to produce numerous types of blocks with different color tones, which makes the block production technology complex and difficult. In addition, since the hue and transparency of the block and each layer structure are adjusted using pigment and dye, discoloration or fading may occur over time, so another problem arises, namely, the hue of the block will no longer match the color of the patient's teeth.

Document PTL 2 refers to a curable composition that does not discolor or fade over time and can provide a cured product having good color tone compatibility with a patient's teeth. The curable composition described in PTL 2 is a dental filler and restorative material, with the color tone compatibility of the composition assessed when the thickness is 2 mm or less, however, it is not described and it is not clear whether there is (or not) color tone compatibility for a thicker product, such as a milled prosthesis.

Therefore, it is an object of the present invention to provide a block of resin for milling in dentistry that is not required to be composed of blocks having different color tones or is not required to have a layered structure having multiple different color tones, which enables restoration of teeth. in such a way that the appearance of block-made dentures without the use of pigment or dye is compatible with the patient's tooth shade, and which produces continuous color tone harmony between the block-made denture and the patient's teeth.

Solution

In discussing the aforementioned problems, the inventors of the present invention made laborious studies. As a result, the inventors have found that dentures made from a dental milling resin block which contain spherical particles having a specific particle size and which exhibit specific color tone characteristics such that when the resin block has a thickness of 10 mm, then a reddish color tone appears on a black background and a white background, and has the same color tone; however, at a thickness of 1 mm, a reddish color tone appears on a black background and no color appears on a white background, and is almost white, has excellent color tone compatibility with the patient's teeth, and can solve the above problems; and the inventors have completed the present invention.

Specifically, the dental milling resin block of the present invention is a dental milling resin block which contains a resin matrix (A) and a spherical filler (B) whose average particle size ranges from 230 nm to 1000 nm, which is such that, at a thickness of 10 mm, the lightness (V) measured with a colorimeter is less than 5.0 and the saturation (C) is less than 2.0, this value being measured in the Munsell color system for colored light on a black background and on a white background, and is such that, at a thickness of 1 mm, the lightness (V) measured with a colorimeter is less than 5.0 and the saturation (C) is 0.05 or more, and this value is measured in the Munsell color system for colored light on a black background, but on a white background, lightness (V) is 6.0 or more and saturation (C) is less than 2.0, and this value is measured in the Munsell color system for colored Sveta.

To obtain a resin block for milling in dentistry, 90% or more of the individual particles constituting the spherical filler (B) are in the range of an average particle size of ± 5%, and

each of the resin matrix (A) and the spherical filler (B) is chosen so as to meet the requirement (X1) expressed by the following inequality (1):

nP<nF (one)

where nP is the refractive index of the resinous matrix (A) at 25°C, and nF is the refractive index of the spherical filler (B) at 25°C.

In a dental milling resin block, preferably the average particle size of the spherical filler (B) is in the range of 240 nm to 500 nm. Dental milling resin block is suitable for processing a cavity in which the dentin part of the tooth is located on a deep surface. Here, the expression "deep surface" means the bottom of the treated cavity and the side walls below the surface where the enamel is located.

More preferably, the dental milling resin block contains inorganic particles (C) having an average particle size of less than 100 nm.

In addition, the present invention provides a method for producing a resin block for dental milling, which contains a resin matrix (A) and a spherical filler (B), the average particle size of which is in the range of 230 nm to 1000 nm; this method involves polymerizing a curable composition that contains a polymerizable monomer, a spherical filler (B) whose average particle size is in the range of 230 nm to 1000 nm, and a polymerization initiator, and in which 90% or more of the individual particles constituting the spherical filler ( B) are in the range of an average particle size of ± 5%, with each of the polymerizable monomer and the spherical filler (B) being chosen to meet the requirement (X2) expressed by the following inequality (2):

nPm<nF (2)

where nPm is the refractive index at 25°C of the polymer obtained by polymerization of the polymerizable monomer, and nF is the refractive index of the spherical filler (B) at 25°C; and wherein the dental milling resin block is such that, at a thickness of 10 mm, as measured by a colorimeter, lightness (V) is less than 5.0 and saturation (C) is less than 2.0, wherein these values are measured in the Munsell color system for colored light on a black background and on a white background, and are such that at a thickness of 1 mm and when measured with a colorimeter, the lightness (V) is less than 5.0 and the saturation (C) is 0 .05 or more, and these values are measured in the Munsell color system for colored light on a black background, however, on a white background, the lightness (V) is 6.0 or more, and the saturation (C) is less than 2.0, and these values are measured in the Munsell color system for colored light.

Benefits of the Invention

The resin block of the present invention for milling in dentistry is such that a dental prosthesis made therefrom can have a different color according to the color tone of the patient's teeth, which varies depending on the individual and the area to be restored, and therefore it is not required that the block The resin had a layered structure of multiple layers having different color tones, and a dental milling resin block can be obtained in a simplified manner. In addition, the denture of the present invention, made from a block of dental milling resin, can be repaired so that its appearance is consistent with the color tone of the patient's teeth, regardless of the size and depth of the restored cavity, and in addition, since optical interference is used. , the resin block is not subject to discoloration or fading, and therefore the harmony between the resulting cured product and the patient's teeth can continue when repaired using the resin block.

Implementation of the invention

The resin block of the present invention for cutting in dentistry is a block having as one component a resin matrix, which is used in the production of dental prostheses using a milling machine based on three-dimensional data stored in a computer. The shape and size are not limited, and any block having the shape and size according to the intended purpose may be selected. The shape is chosen arbitrarily from the shape of a rectangular parallelepiped, a cylindrical shape, a disk, and the like, in accordance with the intended purpose and the milling device used. For example, with regard to size, in the case of a cuboid shape, the length of one side is usually selected in the range of 5 mm to 150 mm, and preferably

10 mm to 150 mm. The volume is usually chosen in the range from 1.8 cm3 to 200 cm3.

The resin block of the present invention for dental milling (hereinafter, sometimes simply referred to as a block) contains a resin matrix (A) and a spherical filler (B) having an average particle size in the range of 230 nm to 1000 nm. The term average particle size of the spherical filler (B) means the average size of the primary particles.

The resin block of the present invention for dental milling has such specific color tone characteristics that when a block of 10 mm in thickness is measured with a colorimeter, the lightness (V) is less than 5.0 and the saturation (C) is less than 2.0 , and these values are measured in the Munsell color system for colored light on a black background (base with lightness 1 according to the Munsell color system) and on a white background (base with lightness 9.5 according to the Munsell color system), and such characteristics that when measuring a block 1 mm thick using a colorimeter, the lightness (V) is less than 5.0 and the saturation (C) is 0.05 or more, and these values are measured in the Munsell color system for colored light on a black background, however, on a white background, lightness (V) is 6.0 or more, and saturation (C) is less than 2.0, and these values are measured in the Munsell color system for colored light.

By adjusting the measured values of colored light for a dental milled resin block on a black background and a white background in the Munsell color system at 10 mm thick and 1 mm thick as above, the color tone compatibility of the resin block with the patient's teeth is improved. The dental milling resin block of the present invention can be used to repair cavities of various sizes, and even when used to repair a relatively large cavity, the color tone compatibility of the resin block is still satisfactory.

When measuring a block with a thickness of 1 mm, when the lightness on a black background is greater than 5.0 and when the saturation is less than 0.05, the resin block is opaque and white without staining, and therefore, when this type of resin block is put on the tooth having a high light intensity (A4 or the like), good color tone compatibility cannot be achieved. By measuring a 1 mm thick block, when the lightness on the white background is less than 6.0 and the saturation is 2.0 or more, the staining on the white background can be confirmed visually, and therefore, when this type of resin block is put on a tooth having low light intensity (A1 or the like), good color tone compatibility cannot be achieved.

Preferably, the lightness (V) of colored light on a black background of a block of dental milling resin that is cut with a thickness of 1 mm is 4.5 or less, more preferably 4.0 or less. Preferably, the saturation (C) of colored light on a black background of a dental milling resin block that is cut with a thickness of 1 mm is 0.07 or more, more preferably 0.09 or more. Preferably, the lightness (V) of the colored light on the white background of the dental milling resin block that is cut in 1 mm thickness is 6.5 or more, more preferably 7.0 or more. Preferably, the saturation (C) of colored light on a white background of a block of dental milling resin that is cut with a thickness of 1 mm is 1.5 or less, more preferably 1.2 or less.

The average particle size of the spherical filler (B) to be injected is from 230 nm to 1000 nm, and therefore the colored light on a black background has a yellow to reddish color, and specifically the shade (H) of the measured values of the colored light, which is measured according to the color Munsell system at a thickness of 1 mm, is in the range of 0 P or more and less than 10 P, 0 RP or more and less than 10 RP, 0 R or more and less than 10 R, 0 YR or more and less, than 10 YR, 0 Y or more and less than 10 Y, and 0 GY or more and less than 10 GY. Preferably, the hue is in the range of 0 P or greater and less than 10 P, 0 RP or greater and less than 10 RP, 0 R or greater and less than 10 R, 0 YR or greater and less than 10 YR, and 0 Y or more and less than 10 Y, more preferably in the range of 0 RP or more and less than 10 RP, 0 R or more and less than 10 R, 0 YR or more and less than 10 YR, and 0 Y or more and less than 10 Y.

With regard to the hue characteristic of a reddish color on a black background, all lightness, saturation, and hue values can be in good harmony even when the color of the environment varies in various ways from reddish yellow to reddish brown, as much as the area around a dental milled dental prosthesis. of the resin block of the present invention is in an environment where it presents a reddish color. Specifically, in the case where the chroma (hue and saturation) of the background (basic environment) is high, external light such as emitted light is absorbed by the background having high chroma and other light other than colored light from a block (or denture) obtained by processing the block) is slowed down, and therefore colored light can be observed. On the other hand, in the case where the chromaticity of the background tooth (basic environment) is low, external light such as emitted light is scattered by the background having low chromaticity, and the scattered light intensity is higher than the colored light from the block (or denture, obtained by processing the block), and therefore the attenuation of the colored light stops. Accordingly, the dental milling resin block of the present invention generates a strong colored light for a base environment having a high chroma, but produces a weak colored light for a base environment having a low chroma, and hence the resin block exhibits an effect largely in accordance with with different reddish environment light.

A dental milling resin block having the specified specific color tone characteristic can be obtained by using a spherical filler (B) having a specific average particle size and having a narrow particle size distribution, and by selecting a resin matrix (A) and a spherical filler ( B) in such a way that their refractive indices can meet the requirement (X1) expressed by the following inequality (1):

nP<nF (one)

where nP is the refractive index of the resin matrix (A) at 25°C, and nF is the refractive index of the spherical filler (B) at 25°C, as described in the following.

As can be seen from expression (1), the resin block of the present invention for milling in dentistry is such that the relationship between the refractive index of the resin matrix (A) and the spherical filler (B) in the block is described by the inequality nP < nF. In the case where the refractive index of the spherical filler (B) is high and the refractive index of the resin matrix is low, colored light can be expressed by interference or scattering, but otherwise, light having a short wavelength can easily interfere or scatter, so that the resulting colored light will have a shortened wavelength and become bluish, that is, this type of resin block will have poor color tone compatibility with processing sites having different color tones.

The resin block of the present invention for milling processing in dentistry is characterized by expressing colored light by the phenomenon of interference and scattering, and the fact that the colored light of the resin block can be expressed can be confirmed by measuring the spectral reflectance characteristics of the block under two conditions: on a black background and on a white background, using a colorimeter. On a black background, in the case where the above requirement (X1) is met, light having a specific visible spectrum (380 to 780 nm) can be clearly confirmed as a specific reflectance spectrum corresponding to colored light, but on a white background, almost uniform reflectivity is observed. in fact, in the entire range of the visible spectrum, that is, the light of the visible spectrum is not confirmed, and the resin block is practically colorless. The reason is that against a black background, external light (eg, illuminant C, illuminant D65) is absorbed or blocked, and the colored light is accentuated by interference. On the other hand, against a white background, it is believed that the scattered reflected light from an external source is strong, and interference-colored light can hardly be observed.

The components included in the resin block of the present invention for milling in dentistry are described below.

Resinous matrix (A)

The resinous matrix (A) of the present invention is a component that plays the role of a dispersion medium for dispersing the spherical filler (B). Without particular limitation, the resinous matrix may be any resin meeting the above requirement (X1), and any thermoplastic resin and thermosetting resin are applicable. From the point of view of the aesthetics of dentures, a resin having a high transparency is preferable. Specifically, it is desirable to use acrylic resins such as polymethyl methacrylate, polyester resins such as polystyrene, polyamide, polycarbonate and polyethylene terephthalate, methyl methacrylate butadiene styrene resins, acrylonitrile butadiene styrene resins, cycloolefin resins, epoxy resins, oxetane resins, or copolymers thereof. . From the viewpoint of safety, high transparency, and ease of refractive index adjustment, it is particularly desirable to use acrylic resins, epoxy resins, and oxetane resins.

Spherical filler (B)

The dental restorative material contains various fillers such as inorganic and organic powders. The dental milling resin block of the present invention contains a spherical filler (B) having an average primary particle size of 230 to 1000 nm for the purpose of expressing colored light by interference. The dental milling resin block of the present invention is characterized in that the constituent filler is spherical and that its particle size distribution is narrow. The interference-colored light is generated in the part in which the constituent spherical filler is accumulated relatively uniformly, and the light colored by scattering is generated in the portion in which the constituent spherical filler is randomly dispersed. Therefore, when the spherical filler (B) constituting the dental milling resin block of the present invention has a uniform spherical shape and its particle size distribution is narrow, colored light is generated by interference. On the contrary, when irregular-shaped filler particles obtained by milling are used, the particle shape is not uniform and the particle size distribution is wide, and therefore the filler cannot be uniformly accumulated and interference-colored light cannot be generated.

As used in the present invention, "the spherical filler is relatively uniformly accumulated" means that the spherical filler is uniformly dispersed in the resin matrix component, in a state that has an isotropic structure oriented according to a certain fixed order.

As described above, it is important that the spherical filler (B) has an average primary particle size of 230 to 1000 nm, and that 90% (by number) or more of the individual particles constituting the spherical filler (B) are in the average particle size range ± 5%. This specifically means that the spherical filler (B) consists of multiple primary particles, with 90% (by number) or more of all primary particles are in the range of average particle size ± 5% of the multiple primary particles. The expression "in the range of average particle size ± 5%" means the range of particle size from 0.95×d to 1.05×d, where d is the average particle size. When 90% (by number) or more of the individual particles constituting the spherical filler (B) are in the average particle size range of ±5%, the intensity of the colored light can be strong and the color tone compatibility with the patient's teeth is improved. The expression of colored light by interference is a consequence of diffraction interference according to the Bragg condition to emphasize light having a specific wavelength, and when particles having the above particle size are mixed, the dental milling resin block can result in the expression of yellow to reddish colored light. according to the size of the particles mixed in the block.

From the point of view of achieving excellent color tone compatibility with tooth substance, for a cavity formed from enamel to dentine, the wavelength of the colored light is preferably 550 to 770 nm, more preferably 580 to 760 nm. Within this range, colored light from a dental milling resin block can be yellow to reddish in color, and therefore the resin block has good color tone compatibility with the patient's teeth. The wavelength of colored light is the wavelength of colored light from a resin block (for dental milling) having a thickness of 1 mm against a black background. The wavelength of the colored light represents the maximum reflectance when measuring the spectral reflectance with a colorimeter, and can be measured according to the method which is described in detail in the Examples section.

From the viewpoint of further enhancing the effect of expressing colored light by interference, the average primary particle size of the spherical filler (B) is preferably 230 to 800 nm, more preferably 240 to 500 nm, even more preferably 260 to 350 nm, most preferably 260 up to 290 nm, and even more preferably from 260 to 275 nm. In the case where the spherical filler particles have a size within the range of 150 nm or more and less than 230 nm, the resulting colored light is blue, and the hue compatibility with the tooth substance is often poor, and furthermore, in the case when a spherical filler with particles smaller than 100 nm is used, the phenomenon of visible light interference hardly occurs. On the other hand, in the case where a spherical filler with particles larger than 1000 nm is used, a phenomenon of light interference may be observed, however, in the resin block of the present invention for dental milling, such large filler particles are undesirable since the polishing performance or milling a block of resin during its processing in dentistry.

The resin block of the present invention for dental milling produces a different colored light on a black background depending on the particle size of the spherical filler (B). Therefore, the average size of the primary particles of the spherical filler (B) can be determined in the range of 230 to 1000 nm so that the light of the desired color can be obtained. When spherical particles with a size ranging from 230 nm to 260 nm are used, a yellowish colored light is obtained, which is used for restoring teeth of the B-type category (red-yellow) of the "VITAPAN Classical" (registered trademark) artificial teeth set. When spherical fillers with a particle size in the range of 260 nm to 350 nm are used, a reddish colored light is obtained, which is used to restore teeth of the A-type category (red-brown) of the "VITAPAN Classical" (registered trademark) artificial teeth set. Because the dentin shade often has such a reddish tint, in the method of the present invention using spherical fillers having an average primary particle size of 260 nm to 350 nm as mentioned above, the resin block most preferably provides such broad and good compatibility with the restoration of teeth of various color tones.

It is important that the size of the primary particles of the spherical filler (B) is in the above average range.

In the present invention, the average particle size of the spherical filler (B) is an average value calculated as follows. The spherical filler powder is imaged using a scanning electron microscope, and the number of all particles (30 particles or more) visible in a single field of view of the image and the size of all primary particles (maximum diameter) are measured, and from the resulting measurement values, calculate the average value according to the following equation:

In the present invention, the proportion (%) of particles within the average particle size range of ±5% of the spherical filler (B) is calculated as follows. Among all particles (30 particles or more) visible in a single image field of view, the number of particles having a primary particle size (maximum diameter) not within the mean particle size range of ±5% as defined above is counted, and the counted value is subtracted from the number of all particles, giving the number of particles within the mean particle size range of ±5% per unit image field of view, and the intended proportion of particles is calculated by the following equation:

The proportion (%) of particles of spherical filler (B) that are within the average particle size range of ± 5% = [(number of particles within the particle size in the average particle size range of ± 5% in a single image field of view in a scanning electron microscope) / (number of all particles in a single field of view of an image in a scanning electron microscope)] × 100.

With regard to particles of a spherical shape, here the spherical filler can be almost spherical, and it is not always necessary that the particles be truly spherical. Usually, particles are imaged using a scanning electron microscope, and the maximum diameter of individual particles (30 particles or more) is measured in a single field of view of the microscope, and the average uniformity is calculated by dividing the particle size in the direction perpendicular to the maximum diameter by the maximum diameter. Thus measured, the average uniformity of the spherical filler, which is relevant to the present invention, may be 0.6 or more, preferably 0.8 or more.

The dental milling resin block of the present invention may contain a spherical filler (B) in any shape as long as the above requirement is met. For example, the spherical filler (B) may be a powdered spherical filler (B) consisting of a spherical filler (B), or may be a composite organic-inorganic filler (B2) containing an inorganic spherical filler (B). A combination of fillers is also used. The organic-inorganic filler (B2) can be obtained, for example, by mixing an aggregate prepared by aggregating the inorganic spherical filler (B) and a polymerizable monomer, followed by polymerizing and curing the resulting mixture, and grinding the cured product.

The spherical filler (B) using the above powder as such may be referred to as the spherical filler (B1), and the organic-inorganic composite filler containing the inorganic spherical filler (B) may be referred to as the organic-inorganic composite filler (B2).

The resin block of the present invention for milling in dentistry may contain a powdered spherical filler (B1) consisting of a spherical filler (B) and an organic-inorganic composite filler (B2). This type of resin block for dental milling is preferred because its mechanical strength can be quite effective.

In the case where the powdered spherical filler (B1) and the organic-inorganic composite filler (B2) are used together, the powdered spherical filler (B1) and the inorganic spherical filler (B) in the organic-inorganic composite filler (B2) may be the same spherical fillers or may be different spherical fillers, but from the viewpoint of improving color tone compatibility, preferably both are the same spherical fillers.

As the spherical filler (B), any filler used as a component of a conventional curable composition in dentistry can be used without limitation. The spherical filler (B) may be an organic spherical filler, or may be an inorganic spherical filler, however, in terms of the fact that by mixing in the block of the present invention, the resulting block can have increased mechanical strength and acquire a glossiness close to that of teeth patient, an inorganic spherical filler is preferred. Specifically, the inorganic spherical filler includes inorganic amorphous silica powders, silica-titanium element oxide composite particles (e.g., silica-zirconia, silica-titanium dioxide), quartz, alumina, barium glass, strontium glass , lanthanum glass, fluoroaluminosilicate glass, ytterbium fluoride, zirconia, titanium dioxide, or colloidal silicon dioxide.

Among these, silica-titanium oxide composite particles are preferable because the refractive power of the filler can be easily controlled.

In the present invention, the silica-titanium element oxide composite particles are a composite silica and an oxide of a titanium group element (Group IV of the Periodic Table of the Elements), and include silica-titanium dioxide, silica-zirconium dioxide, and silica - titanium dioxide - zirconium dioxide. Among them, silica-zirconia is preferable from the viewpoint of being able to adjust the refractive index of the filler and that the filler can provide high X-ray opacity. Although the compounding ratio is not particularly limited, from the viewpoint of providing sufficient X-ray opacity and adjusting the refractive index to be in the preferred range below, it is preferable that the silica content is 70 to 95 mol%, and the oxide content of the group titanium is from 5 to 30 mol.%. In the case of silica-zirconium dioxide, the refractive index of the composition can be varied in any way by changing the compounding ratio.

In addition, the silica-titanium element oxide composite particles can only be compounded with a small amount of any metal oxide other than silica and oxides of the titanium group elements. Specifically, alkali metal oxides such as sodium oxide and lithium oxide can be introduced in an amount of 10 mol% or less.

The production method of said silica-titanium element oxide composite particles is not particularly limited. In order to obtain a specific spherical filler for use in the present invention, for example, it is advantageous to apply the so-called sol-gel method, in which a mixed solution of a hydrolysable organic silicon compound and a hydrolysable organic metal compound from the titanium group is added to an alkaline solvent, and hydrolyzed to precipitate the product. reactions.

The surface of the silica-titanium element oxide composite particles can be treated with a silane coupling agent. By treating the surface with a silane coupling agent, the strength of the interface between the powder particles and the resin matrix (A) can be improved. Examples of typical silane coupling agents include organic silicon compounds such as γ-methacryloyloxyalkyltrimethoxysilane and hexamethyldisilazane. The amount of the silane coupling agent for surface treatment is not particularly limited, and the optimum amount of the agent can be determined by preliminary experimental confirmation of the mechanical properties of the resulting dental milling resin block. An example of a preferred range for the amount of the agent is 0.1 to 15 parts by weight relative to 100 parts by weight of the spherical filler (B).

As mentioned above, colored light due to interference or scattering, which expresses good color tone compatibility with the patient's teeth, can be obtained when the resin matrix (A) and the spherical filler (B) correspond to the following expression (1):

nP<nF (one)

where nP is the refractive index of the resinous matrix (A) at 25°C, and nF is the refractive index of the spherical filler (B) at 25°C.

Specifically, the refractive index of the spherical filler (B) is higher than that of the resinous matrix (A). Preferably, the difference between the refractive index nF (25°C) of the spherical filler (B) and the refractive index nP (25°C) of the resin matrix (A) (nF - nP) is 0.001 or more, more preferably 0.002 or more, most preferably 0.005 or more. With regard to the refractive index, when the transparency of the dental milling resin block is high, the colored light is expressed more sharply, and therefore it is preferable to select and use components such that the difference between the refractive indices (nF - nP) of the spherical filler (B) and the resinous matrix (A) was 0.1 or less, more preferably 0.05 or less, and such that, as far as possible, does not reduce transparency.

In the present invention, the mixing amount of the spherical particles (B) is 10 parts by mass to 1500 parts by mass relative to 100 parts by mass of the resin matrix (A). When the spherical particles (B) are mixed in an amount of 10 parts by mass or more, colored light can be better expressed by interference and scattering. In the case where spherical particles (B) are used such that the difference between the refractive indices of the particles and the resin matrix (A) is larger than the above-mentioned value of 0.1, the transparency of the dental milling resin block is lowered, and the color light expression effect is not may be sufficient. With these considerations in mind, the mixing amount of the spherical particles (B) is preferably 50 parts by weight to 1500 parts by weight relative to 100 parts by weight of the resin matrix (A), more preferably 100 parts by weight to 1500 parts by weight.

Among the spherical fillers (B), the refractive index of the silica-titanium element oxide composite oxide, the refractive index of which is easily controlled, is in the range of about 1.45 to 1.58, depending on the relative content of silica in the filler. . Specifically, in the case where a silica-titanium element oxide composite oxide is used as the spherical filler (B), the refractive index nP of the resin matrix (A) can be adjusted to be in the range of about 1.40 to 1, 57 by adjusting the refractive index of the polymerizable monomer which is the raw material for the resin matrix (A) so that the refractive index is in the range to be indicated below (in the range of 1.38 to 1.55), and therefore, the spherical filler (B) to meet the above requirement (X1). Specifically, a silica-titanium element oxide composite oxide (eg, silica-titanium dioxide or silica-zirconia) which contains an appropriate relative amount of silica can be used.

Organic-inorganic composite filler (B2)

In the present invention, as mentioned above, the spherical filler (B) can be used as a powdered spherical filler (B1) as such, or an organic-inorganic composite filler (B2) can also be used. A dental milling resin block containing an organic-inorganic composite filler (B2) can have improved mechanical strength, and its properties as dentures can be easily improved.

The organic-inorganic composite filler (B2) contains an organic resinous matrix and an inorganic spherical filler (B) dispersed in an organic resinous matrix. Hereinafter, the organic resinous matrix contained in the organic-inorganic composite filler (B2) is called the organic resinous matrix (b1), and the inorganic spherical filler (B) contained in the organic-inorganic composite filler is called the spherical inorganic filler (b2 ).

In the case where the spherical filler (B) is used as a form of the organic-inorganic composite filler (B2), and also in the case where the organic-inorganic composite filler (B2) is added to the dental milling resin block so that the difference between the refractive indices of the spherical inorganic filler (b2) and the organic resinous matrix (b1) constituting the organic-inorganic composite filler (B2), and the difference between the refractive indices of the spherical inorganic filler (b2) and the resinous matrix (A) would satisfy, respectively, the expressions ( 3) and (4) to be mentioned below, diffraction interference of light occurs according to the Bragg diffraction condition, and thus colored light having the same wavelength as when only a spherical filler (B1) having such same average size of primary particles as spherical inorganic th filler (b2).

The spherical inorganic filler (b2) included in the organic-inorganic composite filler (B2) may be the same or different from the spherical filler (B1) used in powder form, but similar to the spherical filler (B1) used in powder form, the filler (b2) is spherical and has an average primary particle size ranging from 230 nm to 1000 nm, it being important that 90% (or more) of the individual particles constituting the spherical inorganic filler (b2) are in the range the average size of the primary particles ± 5%, and in addition, the refractive index nFb2 of the spherical inorganic filler (b2) satisfies the relationship between the refractive index nMb1 of the organic resinous matrix (b1) and the refractive index nFb2 of the spherical inorganic filler (b2) expressed by the following inequality (3) , and the relationship between the refractive index nP of the resin matrix (A) and the index refraction nFb2 of a spherical inorganic filler (b2), expressed by the following inequality (4).

nMb1 < nFb2 (3)

where nMb1 is the refractive index at 25°C of the organic resinous matrix (b1) constituting the organic-inorganic composite filler (B2), and nFb2 is the refractive index at 25°C of the spherical inorganic filler (b2).

nP < nFb2 (four)

where nP is the refractive index at 25°C of the resinous matrix (A), and nFb2 is the refractive index at 25°C of the spherical inorganic filler (b2) constituting the organic-inorganic composite filler (B2).

Specifically, the refractive index nFb2 of the spherical inorganic filler (b2) is higher than the refractive index nP of the resin matrix (A) and higher than the refractive index nMb1 of the organic resin matrix (b1) constituting the organic-inorganic composite filler (B2).

Each refractive index difference (nFb2-nP) between the refractive index nFb2 of the spherical inorganic filler (b2) and the refractive index nP of the resin matrix (A), and the refractive index difference (nFb2-nMb1) between the refractive index nFb2 of the spherical inorganic filler (b2) and the refractive index the refractive index nMb1 of the organic resin matrix (b1) is preferably 0.001 or more, more preferably 0.002 or more, most preferably 0.005 or more.

In addition, each refractive index difference (nFb2-nP) between the refractive index nFb2 of the spherical inorganic filler (b2) and the refractive index nP of the resin matrix (A), and the refractive index difference (nFb2-nMb1) between the refractive index nFb2 of the spherical inorganic filler (b2 ) and the refractive index nMb1 of the organic resin matrix (b1) is preferably 0.1 or less, more preferably 0.05 or less, so as not to reduce transparency as much as possible. The content of the spherical inorganic filler (b2) in the organic-inorganic composite filler (B2) is preferably 30% by mass or more and 95% by mass or less. When its content in the organic-inorganic composite filler (B2) is 30% by mass or more, the block can effectively express colored light, and its mechanical strength can be greatly increased. On the other hand, introducing the spherical inorganic filler (b2) into the organic-inorganic composite filler (B2) in an amount of more than 95% by mass is technically difficult, and in such a case, it is hardly possible to form a uniform filler. A more preferred content of the spherical inorganic filler (b2) in the organic-inorganic composite filler (B2) is 40 to 90% by weight.

Similarly, for the spherical filler (B1) used in powder form, the refractive index of the silica-oxide composite oxide of a titanium group element whose refractive index can be easily controlled among the spherical inorganic fillers (b2) can be in the range of about 1 .45 to 1.58, depending on the relative content of silicon dioxide in the filler. Specifically, in the case where the silica-titanium element oxide composite oxide is used as the spherical inorganic filler (b2), the refractive index nP of the resin matrix can be adjusted to fall in the range of about 1.40 to 1.57 by pre-adjusting the refractive index of the polymerizable monomer which is the raw material for the resin matrix (A) to fall within the above range (1.38 to 1.55), and therefore the spherical inorganic filler (b2) can thus be it is easy to choose to meet the above requirement (expression (4)). Specifically, a silica-titanium oxide composite oxide containing a suitable relative amount of silica (eg, silica-titanium dioxide or silica-zirconium dioxide) can be used.

In the organic-inorganic composite filler (B2), any homopolymer prepared using the same polymerizable monomer as described as the polymerizable starting material monomer for the resin matrix (A) as described below, or any copolymer of numerous kinds of such monomers, can be used, no limitation for organic resin matrix (b1). As described above in the invention, in the case where a silica-titanium element oxide composite oxide whose refractive index is easily controlled is used as a spherical inorganic filler (b2), its refractive index is in the range of about 1.45 up to 1.58, depending on the relative content of silica in the filler, and therefore the above requirement (expression (3)) can be satisfied by adjusting the refractive index nMb1 of the organic resin matrix (b1) to be in the range of about 1.40 up to 1.57.

The organic resin matrix (b1) may be the same as (or different from) the resin matrix (A), but the difference between the refractive index nMb1 of the organic resin matrix (b1) and the refractive index nP of the resin matrix (A) is preferably 0.005 or less , in terms of the transparency of the resulting dental milling resin block. When the difference between said refractive indices is greater than 0.005, the resin block may be opaque and the interference-colored light may be weak. In addition, from the point of view that the diffusing ability of light can be ensured by the difference in refractive index, in order to improve the compatibility of the color tone between the dental milling resin block and the teeth, it is more preferable that the difference between the refractive indices is in the range of 0.001 to 0.005.

In the present invention, the method for producing the organic-inorganic composite filler (B2) is not particularly limited, and the conventional method for producing the organic-inorganic composite filler can be used, which includes: mixing predetermined amounts of each component - spherical inorganic filler (b2), organic resinous matrix ( b1) and polymerization initiator, polymerization of the components in accordance with the methods of heating or photo-irradiation, followed by grinding the resulting product. As described in documents WO2011/115007 and WO2013/039169, the filler can be obtained according to a method for producing an organic-inorganic composite filler, which includes immersing aggregated inorganic particles formed by aggregating a spherical inorganic filler (b2) into a polymerizable monomer solution that contains a polymerizable a monomer, a polymerization initiator and an organic solvent, then removing the organic solvent, polymerizing and curing the polymerizable monomer according to heating or photo-irradiation methods; thus, an organic-inorganic composite filler is obtained which has an organic resin phase covering the surface of each inorganic primary particle of aggregated inorganic particles formed by aggregating the inorganic primary particles, and mutually bonding the inorganic primary particles to each other, and in which aggregation voids are formed between an organic resin phase that coats the surface of each inorganic primary particle. As the polymerization initiator in the invention, the same polymerization initiator as described in the following as the polymerization initiator can be used without limitation, however, from the viewpoint of obtaining a cured product having a reduced yellowness, a thermal polymerization initiator is preferably used, and mainly more preferable is the use of an initiator that includes a compound in the structure of which there is no aromatic ring.

The average particle size of the organic-inorganic composite filler (B2) in the present invention is not particularly limited, but from the viewpoint of improving the mechanical strength of the dental milling resin block, the particle size is preferably 2 to 100 µm, more preferably 5 to 50 µm. , even more preferably from 5 to 30 µm. The average particle size of the organic-inorganic composite filler (B2) can be measured using a laser diffraction scattering technique. Also without particular limitation, the shape of the filler includes randomly shaped particles obtained by mixing predetermined amounts of each component - spherical inorganic filler (b2), organic resin matrix (b1) and polymerization initiator, then polymerizing the component in accordance with methods of heating or photoirradiation, and milling the resulting product, and spherical or almost spherical particles obtained by the method described in documents WO2011/115007 or WO2013/039169.

The organic-inorganic composite filler (B2) may contain any known additive as long as it does not impair its beneficial effect. Specifically, the additive includes a pigment, a polymerization inhibitor and a fluorescent bleach. Generally, these additives can be used in an amount of generally 0.0001 to 5 parts by weight relative to 100 parts by weight of the organic-inorganic composite filler.

The organic-inorganic composite filler (B2) may be washed or its surface may be treated with a silane coupling agent.

In the present invention, the amount of the organic-inorganic composite filler (B2) to be mixed in the case where the powdered spherical filler (B1) is not used as the spherical filler (B) and the organic-inorganic composite filler (B2) alone is used is 50 to 1000 parts by weight relative to 100 parts by weight of the resinous matrix (A); and in order to improve the mechanical strength of the dental milling resin block, the organic-inorganic composite filler (B2) may be admixed preferably in an amount of 70 to 800 parts by mass, more preferably 100 to 600 parts by mass. The amount of miscible spherical inorganic filler (b2) in the organic-inorganic composite filler is as described above in the invention, preferably 30% by mass or more and 95% by mass or less, more preferably 40 to 90% by mass. Accordingly, the mixing amount of the spherical inorganic filler (b2) that contributes to the expression of colored light by interference is 10% by mass ((50/150) × 30%) or more and 86.4% by mass ((1000/1100) × 95%) or less. In the case where the spherical filler (B1), which is used in the form of a powder, and the organic-inorganic composite filler (B2) are used together, both components can be combined so that the total amount of spherical filler (B1) and spherical inorganic filler (b2) to be mixed ) in the organic-inorganic composite filler (B2) can be from 10 to 86% by weight in the dental milling resin block, to improve the expression of colored light through interference. The total mixing amount of the spherical filler (B1) and the spherical inorganic filler (b2) in the organic-inorganic composite filler (B2) is more preferably 15% by mass to 86% by mass in a dental milling resin block, even more preferably from 20% by weight to 86% by weight. To further improve the mechanical strength of the dental milling resin block, the mixing ratios (by weight) of the spherical filler (B1) and the organic-inorganic composite filler (B2) are preferably 90/10 to 10/90, more preferably 80/20 up to 20/80, even more preferably from 70/30 to 30/70.

Specifically, the amount of miscible spherical filler (B) in the dental milling resin block is preferably 10 to 86% by mass, more preferably 15 to 86% by mass, even more preferably 20 to 86% by mass. Here, the mixing amount of the spherical filler (B) when the powdered spherical filler (B1) is used as the spherical filler (B) means the mixing amount of the powdered spherical filler (B1) when the spherical filler (B) is used as an organic-inorganic composite filler ( B2) means the mixing amount of the spherical inorganic filler (b2) in the organic-inorganic composite filler (B2), and when the powdered spherical filler (B1) and the organic-inorganic composite filler (B2) are used together, means the total amount of the spherical filler (B1) and a spherical inorganic filler (b2) in an organic-inorganic composite filler (B2).

Inorganic particles (C)

In the resin block of the present invention for dental milling, it is possible to further mix inorganic particles (C) having an average primary particle size of less than 100 nm, in addition to a spherical filler (B) whose average primary particle size is in the range of 230 to 1000 nm, in order to effectively express the colored light of the cured product through interference in order to further improve the color tone compatibility of the product.

The inorganic particles (C) have an average primary particle size of less than 100 nm, which almost does not cause the visible light interference phenomenon as described above, and therefore does not inhibit the expression of colored light by interference in the present invention. Therefore, by incorporating inorganic particles (C) into the dental milling resin block, its transparency can be adjusted according to the mixing amount of inorganic particles (C) while maintaining the desired colored light expression.

The average primary inorganic particle size (C) in the present invention is preferably 1 to 99 nm, more preferably 10 to 90 nm, even more preferably 10 to 70 nm.

As the inorganic particles (C), the particles used in the present invention as the spherical filler (B) can be used without any limitation. Specifically, inorganic powders of amorphous silicon dioxide, composite particles based on silicon dioxide-oxide of an element from the titanium group (for example, silicon dioxide-zirconium dioxide, silicon dioxide-titania), quartz, alumina, barium glass, strontium glass, lanthanum glass, fluoroaluminosilicate glass, ytterbium fluoride, zirconia, titanium dioxide, or colloidal silicon dioxide.

Among these, amorphous silica particles and silica-titanium element oxide composite particles are preferable because the refractive power of the filler can be easily controlled.

The surface of these silica-titanium element oxide composite particles can be treated with a silane coupling agent, similar to the spherical filler (B). By surface treatment with a silane coupling agent, the interface strength of the resin matrix (A) in the dental milling resin block of the present invention can be improved. Examples of typical silane coupling agents include organic silicon compounds such as γ-methacryloyloxyalkyltrimethoxysilane and hexamethyldisilazane. The amount of the silane coupling agent for surface treatment is not particularly limited, and its optimum amount can be determined by preliminary experimental confirmation of the mechanical properties of the resulting dental milling resin block. An example of a preferred range for the amount of the agent is 0.1 to 15 parts by weight relative to 100 parts by weight of the inorganic particles (C).

In the present invention, the mixing amount of the inorganic particles (C), from the viewpoint of color tone compatibility with the patient's teeth, is preferably 0.1 to 50 parts by mass relative to 100 parts by mass of the resin matrix (A), more preferably 0.2 to 30 parts by weight, even more preferably 1 to 20 parts by weight.

As a typical method for restoring teeth, for example, a method of filling a cavity with a paste-like curable composition containing a (meth)acrylate-based polymerizable monomer and inorganic particles and curing it in the cavity is known. However, when a relatively large amount of inorganic particles (C) having a small average particle size like those used in the present invention are mixed in said paste-like curable composition, the viscosity of the resulting composition increases, which deteriorates its workability. However, in the present invention, not a paste composition but a pre-cured block is used, and therefore its workability is not impaired. Therefore, the block of the present invention containing mixed inorganic particles (C) retains good workability in restoring teeth, and as mentioned above, the color tone compatibility of the block with the patient's teeth is good.

In addition, since the block does not have the risk of deterioration in workability mentioned above, a relatively large amount of inorganic particles (C) can be mixed therein, and therefore the amount of the resin component can be small, which easily prevents polymerization cracking in block production.

Other additives

Any known additives other than the above-mentioned components (A) to (C) can be mixed into the resin block of the present invention for dental milling in a range that does not impair the beneficial effects of the resin block. Specifically, a polymerization inhibitor and a UV absorber may be added to the block.

In the present invention, as described above, a dental milling resin block can be obtained that achieves good restoration with a single-layer block and has good color tone compatibility with the patient's teeth even if coloring agents such as pigments are not used. Therefore, an embodiment of the invention without the addition of a pigment, which creates a risk of discolouration over time, is preferred. However, the present invention does not renounce the admixture of the pigment itself, which can be added in such an amount as not to interfere with the formation of colored light by interference from the spherical filler. Specifically, the pigment may be added in an amount of about 0.0005 to 0.5 parts by weight relative to 100 parts by weight of the resin matrix (A), preferably about 0.001 to 0.3 parts by weight.

Method for obtaining a block of resin for milling in dentistry

The production method of the dental milling resin block of the present invention is not particularly limited, and suitable production methods can be creatively used according to the materials used. For example, in the case where the resinous matrix (A) is a thermoplastic resin, the method of heating and melting a pasty mixture that contains the resinous matrix (A) and spherical filler (B) can be used (if necessary, any other components can be added to the mixture, such as as the aforementioned inorganic particles (C)), then successively inject the obtained melt into the interior of the mold and form a block, or a method for successively pressing the melt into the interior of the mold in the same manner. The spherical filler (B) to be in the dough mixture may be a powdered spherical filler (B1), or may be in the form of an organic-inorganic composite filler (B2), or may be a combination of a spherical filler (B1) and an organic-inorganic composite filler (B2).

By preparing a curable composition containing a polymerizable monomer which is a starting material for a resin matrix (A), a spherical filler (B) and a polymerization initiator (and any other components such as the aforementioned inorganic particles (C) can be added to the composition if necessary) , polymerization and curing of the composition, it is also possible to obtain a resin block for milling in dentistry.

The spherical filler (B) to be in the curable composition may be a powdered spherical filler (B1), or may be in the form of an organic-inorganic composite filler (B2), or may be a combination of a spherical filler (B1) and an organic-inorganic composite filler (B2). In such a case, during the manufacturing process, the materials are dosed, filled in a mold, molded and defoamed inside the mold, and optionally heat or light prepolymerized, and then finally heat or light polymerized to obtain a block. In addition, if desired, the resulting block can be further processed by polishing or heat treated.

polymerizable monomer

In the case where a curable composition containing a polymerizable monomer that can be a raw material for a resin matrix (A), a spherical filler (B), and a polymerization initiator is polymerized and cured to form a dental milling resin block, the polymerizable monomer that will resin matrix starting material is not specifically limited as long as it meets, with respect to the spherical filler (B), the requirement (X2) expressed by the following inequality (2)

nPm < nF (2)

where nPm is the refractive index at 25°C of a polymer obtained by polymerization of a polymerizable monomer, and nF is the refractive index of a spherical filler (B) at 25°C, and includes a radically polymerizable monomer, and a cationic polymerizable monomer such as epoxy and oxetane connections. The (meth)acrylate monomer is preferably used as the radically polymerizable monomer due to its good polymerizability. Examples of (meth)acrylate polymerizable monomers include the following (a) to (c).

(a) Difunctional polymerizable monomers:

(i) Aromatic type monomers:

2,2-bis (methacryloyloxyphenyl) propane,

2,2-bis[(3-methacryloyloxy-2-hydroxypropyloxy)phenyl]propane,

2,2-bis(4-methacryloyloxyphenyl)propane,

2,2-bis(4-methacryloyloxypolyethoxyphenyl)propane,

2,2-bis(4-methacryloyloxydiethoxyphenyl)propane,

2,2-bis(4-methacryloyloxytetraethoxyphenyl)propane,

2,2-bis(4-methacryloyloxypentaethoxyphenyl)propane,

2,2-bis(4-methacryloyloxydipropoxyphenyl)propane,

2-(4-methacryloyloxydiethoxyphenyl)-2-(4-methacryloyloxytriethoxyphenyl) propane,

2-(4-methacryloyloxydipropoxyphenyl)-2-(4-methacryloyloxytriethoxyphenyl)propane,

2,2-bis(4-methacryloyloxypropoxyphenyl)propane,

2,2-bis(4-methacryloyloxyisopropoxyphenyl)propane,

and acrylates corresponding to said methacrylates;

and diadducts derived from an adduct of a vinyl monomer having an -OH group, such as methacrylate, for example,

2-hydroxyethyl methacrylate,

2-hydroxypropyl methacrylate, and

3-chloro-2-hydroxypropyl methacrylate or acrylate corresponding to said methacrylate, and a diisocyanate compound having an aromatic group such as methylbenzene diisocyanate and 4,4'-diphenylmethane diisocyanate.

(ii) Aliphatic type monomers:

ethylene glycol dimethacrylate,

diethylene glycol dimethacrylate,

triethylene glycol dimethacrylate,

tetraethylene glycol dimethacrylate,

neopentyl glycol dimethacrylate,

1,3-butanediol-dimethacrylate,

1,4-butanediol-dimethacrylate,

1,6-hexanediol-dimethacrylate,

and acrylates corresponding to said methacrylates;

diadducts prepared from an adduct of a vinyl monomer having an -OH group, such as methacrylate, e.g.

2-hydroxyethimethacrylate,

2-hydroxypropyl methacrylate, and

3-chloro-2-hydroxypropyl methacrylate, or acrylates corresponding to said methacrylates, and diisocyanate compounds such as

hexamethylene diisocyanate,

trimethylhexamethylene diisocyanate,

methylcyclohexane diisocyanate, isophorone diisocyanate, methylene bis(4-cyclohexyl isocyanate);

1,2-bis(3-methacryloyloxy-2-hydroxypropyl)ethyl,

1,6-bis(methacrylethyloxycarbonylamino)trimethylhexane.

(b) Trifunctional polymerizable monomers:

methacrylates such as trimethylolpropane trimethacrylate,

trimethylolethane trimethacrylate,

pentaerythritol-trimethacrylate,

trimethylolmethane-trimethacrylate,

and acrylates corresponding to said methacrylates;

(c) Tetrafunctional polymerizable monomers:

pentaerythritol-tetramethacrylate,

pentaerythritol tetraacrylate; and

diadducts derived from the adduct of a diisocyanate compound, such as

methylbenzene diisocyanate,

methylcyclohexane diisocyanate,

isophron diisocyanate,

hexamethylene diisocyanate,

trimethylhexamethylene diisocyanate,

methylenebis(4-cyclohexyl-isocyanate),

4,4-diphenylmethane-diisocyanate,

toluene-2,4-diisocyanate, and glycidol-dimethacrylate.

If necessary, multiple kinds of said polyfunctional polymerizable monomers of the (meth)acrylate type can be used, in combination.

In addition, any polymerizable monomers other than the aforementioned (meth)acrylate type monomers can also be used if necessary.

In the present invention, with respect to the polymerizable monomers that can be the starting material for the resin matrix (A), multiple types of polymerizable monomers are generally used to control the characteristics (mechanical properties and tooth adhesion for dental use) of a dental milling resin block, and In this case, preferably, the type and amount of the polymerizable monomer is determined so that the refractive index of the resin matrix (A) at 25°C can fall in the range of 1.38 to 1.55 in terms of the difference between the refractive indices of the resin matrix and the spherical filler (B). Specifically, in the case where a silica-titanium element oxide composite oxide whose refractive index is easily controlled is used as a spherical filler (B), its refractive index nF may be in the range of about 1.45 to 1. 58, depending on the relative content of silica, and in such a case that the refractive index of the polymerizable monomer that can be the raw material for the resin matrix (A) is adjusted to be in the range of 1.38 to 1.55, then the refractive index nP of the resinous matrix (A) may be such as to be in the range of approximately 1.40 to 1.57, which is quite consistent with expression (1). Depending on the circumstances, multiple types of polymerizable monomers are used for the resinous matrix (A), and the refractive index of the resinous material (A) in this case is the refractive index of the cured mixture of these multiple types of polymerizable monomers, and it is good that the refractive index falls within the above-mentioned range , that is, it is not always required that the refractive index of each cured polymerizable monomer be in this range.

The refractive index of the resinous matrix (A) and polymerizable monomer can be measured at 25°C using an Abbe refractometer.

polymerization initiator

In the case where the polymerizable monomer is used as a raw material for the resin matrix (A), a polymerization initiator is preferably used to polymerize and cure the polymerizable monomer. As a polymerization method of the curable composition, the invention uses any method of interaction with light energy, such as UV radiation or visible radiation (hereinafter referred to as photopolymerization), or chemical interaction with peroxide and an accelerator, or interaction with thermal energy (hereinafter referred to as thermal polymerization) . From the viewpoint that the calculation of the polymerization time can be arbitrarily selected according to external energy such as light or heat, and that the operation is simple, photopolymerization or thermal polymerization is preferable. The various polymerization initiators mentioned below may be appropriately selected and used, depending on the polymerization method used.

Examples of useful photoinitiators 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; benzophenones such as benzophenone, 4,4'-dimethylbenzophenone and 4-methacryloxybenzophenone; α-diketones such as diacetyl, 2,3-pentadione-benzyl, camphor quinone, 9,10-phenanthraquinone, and 9,10-anthraquinone; thioxanthone compounds such as 2,4-diethoxythioxanthone, 2-chlorothioxanthone, and methylthioxanthone; and acylphosphine oxides such as 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, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

Often a reducing agent is added to the photoinitiator, and examples thereof include tertiary amines such as 2-(dimethylamino)ethyl methacrylate, 4-dimethylaminobenzoic acid ethyl ester, and N-methyldiethanolamine; aldehydes such as lauryl aldehyde, dimethylaminobenzaldehyde, and terephthalic acid aldehyde; and compounds containing sulfur such as 2-mercaptobenzoxazole, 1-decanethiol, thiosalicylic acid, and thiobenzoic acid.

Examples of thermal polymerization initiators include peroxides such as benzoyl peroxide, p-chlorobenzoyl peroxide, t-butyl peroxy-2-ethyl hexanoate, t-butyl peroxy dicarbonate, and diisopropyl peroxy dicarbonate; azo compounds such as azobisisobutyronitrile; boron compounds such as tributylborane, tributylborane partial oxide, sodium tetraphenylborate, sodium tetrakis(p-fluorophenyl)borate, and triethanolamine tetraphenylboronic acid salt; barbituric acids such as 5-butylbarbituric acid and 1-benzyl-5-phenylbarbituric acid; sulfinates such as sodium benzenesulfinate and sodium p-toluenesulfinate.

Only one or two or more types of said polymerization initiators may be used either alone or in combination. The amount of polymerization initiators to be mixed is preferably 0.01 to 5 parts by weight relative to 100 parts by weight of the polymerizable monomer.

Application Method of Resin Block for Milling in Dentistry

The block thus obtained as above, optionally after attaching a plug to it to secure the block to a CAD/CAM device, is suitable for use as a CAD/CAM block. The block can be connected to a CAD/CAM device and cut as designed to form a dental prosthesis such as an inlay, onlay, crown, bridge, or top of an implant structure.

The dental milling resin block of the present invention can be used to repair a cavity of any size, and is successfully used to repair even a large cavity. Therefore, the dental milling resin block of the present invention is advantageously used as a dental prosthesis such as the aforementioned inlay, onlay, crown, bridge, and top of an implant structure.

Examples

Hereinafter, the present invention is described more specifically with reference to the Examples, however, the present invention is in no way limited to these Examples.

Methods for determining various characteristics in the present invention are listed below.

(1) Average size of primary particles of spherical filler (B) and inorganic particles (C)

Using a scanning electron microscope (from Philips N.V., "XL-30S"), an image of the analyzed powder is obtained at 5,000 to 100,000 times magnification, and using an image analysis software (product name "IP-1000PC", from Asahi Kasei Engineering Corporation), manipulate the image, and count the number of particles (30 or more particles) visible in a single field of view of the image, and measure the primary particle size (maximum diameter) of the powder. From the measured data, calculate the number average primary particle size according to the following equation:

(среднечисленный)

(average)

(n: number of particles, xi: primary particle size (maximum diameter) of the i-th particle)

(2) Fraction of particles falling within the average particle size range in the spherical filler (B)

The proportion (in %) of particles within the ±5% average primary particle size range in the spherical filler (B) is calculated as follows. Among all particles (30 particles or more) in a single image field of view, count the number of particles having a primary particle size (maximum diameter) not within the range of average primary particle size ± 5% by the method above, and subtract this number from the number of all particles, obtaining the number of particles that are within the range of the average size of primary particles ± 5% in a single field of view of the image, and the proportion (%) of particles that are within the range of the average size of primary particles ± 5%, in the spherical filler (B) is calculated from following equation:

Percentage (%) of particles within ±5% average primary particle size range in spherical filler (B) = [(number of particles within particle size within ±5% average particle size range, per single SEM image field) /(number of all particles in a single field of view of an image in a scanning electron microscope)] × 100.

(3) Average uniformity of spherical filler (B)

Using a scanning electron microscope, an image of the particles of the analyzed powder is obtained, and in this image, the number of particles (n = 30 or more) visible in a single field of view is determined, and the maximum particle diameter is measured as the main diameter (Li), and the particle diameter in the direction perpendicular to the main diameter as the minor diameter (Bi), and calculate the average uniformity of the spherical filler (B) using the following equation.

(4) Average particle size (granularity) of organic-inorganic composite filler

0.1 g of organic-inorganic composite filler is dispersed in 10 ml of ethanol and treated with ultrasonic waves for 20 minutes. Using a particle size analyzer ("LS230", from Beckman Coulter Inc.) according to the laser diffraction scattering method, and in addition using the optical model "Fraunhofer", the average particle diameter in the volume statistics of the filler is determined.

(5) Refractive index measurements

Refractive index (nP) resin matrix (A)

The refractive index of the resin matrix (A) used is the refractive index of the polymer obtained by polymerization of the polymerizable monomer starting material for the resin matrix (A). Specifically, the refraction of the polymer obtained by polymerization under the same conditions as the production of a dental milling block was measured in a temperature-controlled room at 25°C using an Abbe refractometer (from Atago Co., Ltd.).

Specifically, a homogeneous mixture of polymerizable monomer, with addition of 0.5% by mass of benzoyl peroxide (BPO), is introduced into a mold having a through hole of 7 mmφ×0.5 mm, and a polyester film is pressure-bonded on both surfaces of the mold. Subsequently, the mixture is polymerized and solidified by heating under nitrogen pressure for 1 hour, and then the resulting resin matrix (A) is removed from the mold. When placing the resin matrix in an Abbe refractometer (manufactured by Atago Co., Ltd.), the sample is not melted, and a solvent (bromonaphthalene) having a higher refractive index than the sample is added dropwise to the measured sample to hermetically bond the matrix and the measured surfaces.

Refractive index nMb1 of the organic resin matrix (b1)

The refractive index of the organic resin matrix (b1) is the refractive index of a polymer obtained by polymerizing a polymerizable monomer starting material for the organic resin matrix (b1). Specifically, the polymer obtained by polymerization under substantially the same conditions as those for the production of the organic-inorganic composite filler was analyzed in a temperature-controlled room at 25°C using an Abbe refractometer (from Atago Co., Ltd.).

Specifically, a homogeneous polymerizable monomer (or a homogeneous mixture of polymerizable monomer) mixed with azobisisobutyronitrile (AIBN, 0.5% by mass) is introduced into a mold having a through hole of 7 mmφ × 0.5 mm, and a polyester film is pressure-bonded onto both surfaces of the form. Subsequently, the mixture is polymerized and solidified by heating under nitrogen pressure for 1 hour, and then the organic resinous matrix (b1) is removed from the mold. When placing the organic resin matrix in an Abbe refractometer (manufactured by Atago Co., Ltd.), the sample is not melted, and a solvent (bromonaphthalene) having a higher refractive index than the sample is added dropwise to the sample to be measured to seal the matrix and measured surface.

Refractive index of spherical filler (B) and inorganic particles (C)

The refractive index of the applied spherical filler (B) and inorganic particles was measured according to the immersion method using an Abbe refractometer (manufactured by Atago Co., Ltd.).

Specifically, in a thermostated room at 25° C., 1 g of spherical filler (B) (or inorganic particles (C) or a surface-treated sample thereof) is dispersed in 50 ml of anhydrous toluene in a 100 ml sample flask. While stirring the resulting dispersion with a stirrer, 1-bromotoluene is gradually added to the mixture dropwise, and the refractive index of the dispersion is measured at the moment when the dispersion becomes most transparent, and the value thus measured is called the refractive index of the inorganic filler.

(6) Visual evaluation of colored light

A cured sample having a length of 7 mm, a width of 7 mm, and a thickness of 1 mm was cut from a dental milling resin block obtained in the Examples and Comparative Examples, and laid out on the adhesive surface of a black adhesive tape (graphite tape) having a square side of approximately 10 mm so that the thickness direction of the cured sample is vertical to the adhesive surface and the color tone of the colored light of the sample can be visually judged.

(7) Wavelength of colored light

A cured sample having a length of 7 mm, a width of 7 mm, and a thickness of 1 mm was cut from the dental milling resin block obtained in the Examples and Comparative Examples, and using a colorimeter (from Tokyo Denshoku Co., Ltd., "TC- 1800MKII") measure the spectral reflectance of the sample on a black background (base with a lightness of 1 according to the Munsell color system) and on a white background (base with a lightness of 9.5 according to the Munsell color system), and the point of maximum reflectivity on a black background is called the wavelength colored light. The cured sample is placed so that the thickness direction of the sample is vertical to the base surface.

(8) Hue, Lightness, Saturation

In the same manner as above, each cured sample having a thickness of 1 mm or 10 mm is cut from a block of dental milling resin. Using a colorimeter (manufactured by Tokyo Denshoku Co., Ltd., "TC-1800MKII"), for each cured sample having a different thickness, hue (H), lightness (V) and saturation (C) were measured according to the Munsell color system on black. background (base with lightness 1 according to the Munsell color system) and against a white background (base with lightness 9.5 according to the Munsell color system), according to JIS Z8722. In addition, in the same manner as above, the cured sample is placed so that the thickness direction of the sample is vertical with respect to the surface of the base.

(9) Color tone compatibility evaluation

To assess shade compatibility, a model restoration tooth (hard resin tooth) consisting of a dentin part and an enamel part, in which the dentin part is covered by the enamel part, is used. Specifically, the dental milling resin block prepared in the Examples and Comparative Examples was cut out to obtain a denture (for restoration) so that the denture thus obtained would be compatible with the lost part of the model tooth for restoration, which is to reproduce a cavity. Class II (Diameter: 5 mm, Depth: 3 mm) lower right, number 6 (transverse diameter 10 mm: abutment/cavity-forming model tooth [A55AN-465], right mandible 6, second class cavity MOD, from the company NISSIN Corporation), and then using Estecem II (cement with adhesive resin, from Tokuyama Dental Corporation), the model is bonded and polished to visually confirm color tone compatibility. As a model for tooth restoration in the invention, a model tooth with high saturation and high chroma (corresponding to A4) and a model tooth with low saturation and low chromaticity (corresponding to A1) ranging from A category (red-brown) in an artificial tooth set "VITAPAN Classical (registered trademark)", and a model tooth with high saturation and high chroma (corresponding to B4) and a model tooth with low saturation and low chroma (corresponding to B1), ranging from B category (red-yellow) in the headset artificial teeth "VITAPAN Classical (registered trademark)".

Criteria for evaluating color tone compatibility:

A. The color tone of the restoration is well matched with the restoration model.

Depending on the degree of compatibility, samples are evaluated in more detail in two classes A1 > A2. This score means that A1 is much better in color tone compatibility than A2.

B. The color tone of the restoration is similar to that of the restoration model.

Depending on the degree of similarity, samples are evaluated in more detail in two classes B1 > B2. This score means that B1 is much better in color tone compatibility than B2.

C: The color tone of the restoration is similar to that of the restoration model, but its compatibility is not satisfactory.

D: The shade of the restoration is not compatible with the shade of the restoration model.

(10) Changing color tone over time

A cured sample of 7 mmφ×1 mm was cut out from the dental milling resin block prepared in the Examples and Comparative Examples and stored in water at 37°C for 4 months. Then, using a colorimeter (manufactured by Tokyo Denshoku Co., Ltd., "TC-1800MKII"), the hue of each sample was measured, and the hue difference before and after storage was expressed as ΔE* according to CIE Lab.

ΔE*={(ΔL*)2+(Δa*)2+(Δb*)2}1/2

∆L*=L1*- L2*

∆a*=a1*- a2*

∆b*=b1*-b2*

where L1* means the lightness index of the cured sample after storage; a1* and b1* are color quality values after storage; L2* means the lightness index of the cured sample before storage; a2* and b2* are color quality values before storage; and ΔE* means the degree of change in hue.

(11) Evaluation of bending strength

A test specimen having a width of 2 mm and a length of 25 mm was cut from a dental milling resin block prepared in the Examples and Comparative Examples, and polished with No. 1500 waterproof sandpaper in the longitudinal direction of the test specimen thus cut, which had a thickness 2 ± 0.1 mm.

Using a universal tensile tester with a chart recorder (manufactured by Shimadzu Corporation), the specimen was examined in a three-point bending test under conditions of 20 mm distance between support points and 1 mm/min traverse speed, at room temperature in air. Five test specimens were examined to determine their flexural strength, and these data were averaged to obtain the average flexural strength of the test specimens.

In the Examples and Comparative Examples, polymerizable monomer, polymerization initiator and organic particles are used.

Polymerizable monomer

1,6-bis(methacrylethyloxycarbonylamino)trimethylhexane (hereinafter the abbreviation "UDMA" is used)

Triethylene glycol dimethacrylate (hereinafter the abbreviation "3G" is used)

2,2-bis[(3-methacryloyloxy-2-hydroxypropyloxy)phenyl]propane (hereinafter referred to as "bis-GMA")

polymerization initiator

Benzoyl peroxide (hereinafter the abbreviation "BPO" is used)

Azobisisobutyronitrile (hereinafter the abbreviation "AIBN" is used)

Inorganic particles (C)

Reoroseal QS-102 (average primary particle size 12 nm, from Tokuyama Corporation)

Dyes

Titanium dioxide (white pigment)

Pigment yellow (yellow pigment)

Pigment red (red pigment)

Pigment blue (blue pigment)

As shown in Table 1, polymerizable monomers are mixed to prepare matrices M1, M2 and M3.

Table 1

Monomer Components of the polymerizable monomer Refractive index before curing after curing M1 UDMA(60)/3G(40) 1.474 1.509 M2 bis-GMA(50)/3G(50) 1.506 1,540 M3 bis-GMA(30)/3G(70) 1.488 1.528

In Table 1, the values in parentheses are parts by weight.

Obtaining a spherical filler and an irregularly shaped filler

The spherical filler is prepared according to the method described in JP 58-110414 A or JP 58-156524 A, in which the precipitated reaction product is obtained by the so-called sol-gel process - adding a mixed solution that contains a hydrolysable organic silicon compound (for example, tetraethyl silicate ) and a hydrolysable organic compound of a metal from the titanium group (for example, tetrabutyl zirconate or tetrabutyl titanate) into an alcohol containing ammonia (for example, methanol, ethanol, isopropyl alcohol or isobutyl alcohol), into which aqueous ammonia is introduced, and subsequent hydrolysis of the solution gives a precipitate of the reaction product , and then the precipitate is dried and optionally crushed and calcined.

An irregularly shaped filler is prepared according to the method described in JP 2-132102 A or JP 3-197311 A, in which an alkoxysilane compound is dissolved in an organic solvent, then water is added to the solution to partially hydrolyze the compound, and in addition, any other metal alkoxide is added or an alkali metal compound to form a complex to hydrolyze the compound to form a gel product, and then the gel product is dried and optionally crushed and calcined.

The spherical filler (B) and the irregular filler used in the Examples are silica-zirconia composite particles based on silica-titanium oxide element, and the details of the particles are shown in Table 2.

The spherical filler (B) listed in Table 2 is used as the starting material (spherical inorganic filler (b2)) to prepare the organic-inorganic composite filler (B2) or as the powdered spherical filler (B1) to be mixed in the Examples.

table 2

The composition and form of the filler Average
the size
particles (nm) Show-
body refraction
leniya Proportion (%) of particles in the range of average particle size (%)* Average uniformity Composition (mol.%) The form PF1 SiO2 / ZrO2 /Na2O=
89.8 / 9.0 / 1.2 spherical 178 1.515 91 0.98 PF2 SiO2 / ZrO2 /Na2O=
89.8 / 9.0 / 1.2 spherical 230 1.515 92 0.97 PF3 SiO2 / ZrO2 /Na2O=
89.8 / 9.0 / 1.2 spherical 303 1.515 90 0.92 PF4 SiO2 / ZrO2 /Na2O=
89.8 / 9.0 / 1.2 spherical 80 1.515 92 0.94 PF5 SiO2 / ZrO2 /Na2O=
89.8 / 9.0 / 1.2 spherical 280 1.515 94 0.94 PF6 SiO2 / ZrO2 /Na2O=
88.7 / 10.1 / 1.2 spherical 282 1.522 93 0.92 PF7 SiO2 / ZrO2 /Na2O=
83.9 / 14.3 / 1.8 spherical 286 1.542 91 0.90 PF8 SiO2 / TiO2 /Na2O=
90.1 / 8.7 / 1.2 spherical 280 1.522 95 0.95 PF9 SiO2 / ZrO2 /Na2O=
88.7 / 10.1 / 1.2 spherical 340 1.522 88 0.93 PF10 SiO2 / ZrO2 /Na2O=
88.7 / 10.1 / 1.2 spherical 260 1.522 93 0.94 PF11 SiO2 / ZrO2 /Na2O=
89.8 / 9.0 / 1.2 wrong-
naya form 500 1.515 fifty -

* The proportion of particles in the range of average particle size means the proportion of particles in the range of average particle size ± 5%.

Obtaining an organic-inorganic composite filler of irregular shape

The thermal polymerization initiator (AIBN) is pre-dissolved in the matrix shown in Table 1 in an amount of 0.5% by weight, and a predetermined amount (Table 3) of the spherical inorganic filler or the irregularly shaped inorganic filler shown in Table 2 is added thereto, and stirred in a mortar to prepare a paste which polymerizes and cures by heating under nitrogen pressure at 95° C. for 1 hour. The cured product is pulverized with a vibrating ball mill, and subjected to a surface treatment with γ-methacryloyloxypropyltrimethoxysilane (0.02% by mass) by boiling in ethanol at 90°C for 5 hours to obtain organic-inorganic composite fillers CF1 - CF13 of irregular shape, which are listed in Table 3.

Obtaining an organic-inorganic composite filler of almost spherical shape

200 g of water was added to 100 g of the spherical inorganic filler listed in Table 2 and processed using an SC mill (from Nippon Coke & Engineering Co., Ltd.) to obtain an aqueous dispersion (spherical inorganic filler dispersion).

On the other hand, 4 g (0.016 mol) of γ-methacryloyloxypropyl-trimethoxysilane and 0.003 g of acetic acid are added to 80 g of water, and stirred for 1 hour and 30 minutes to obtain a homogeneous solution having a pH of 4. This solution is added to the above dispersion of spherical inorganic filler and mix until homogeneous. Subsequently, with weak agitation, the dispersion is applied to a disk rotating at high speed and granulated according to the spray drying method.

Spray drying was carried out using a TSR-2W spray dryer (manufactured by Sakamoto Giken Co., Ltd.) equipped with a rotating disk for centrifugal spraying. The rotation speed of the disk is 10,000 rpm and the temperature of the dry air is 200°C. Subsequently, the powder thus obtained by spray-drying granulation was vacuum-dried at 60° C. for 18 hours to obtain 73 g of nearly spherical aggregated particles.

Then, to the matrix indicated in Table 1, add the thermal polymerization initiator - AIBN in the amount of 0.5% by weight and, in addition, add a given amount (Table 3) of the above aggregated particles to a solution of the polymerizable monomer mixed with an organic solvent - methanol ( contains 36 parts by weight of polymerizable monomer relative to 100 parts by weight of organic solvent), and the particles are impregnated. After confirming that the suspension is fully mixed, the resulting mixture is kept statically for 1 hour.

The mixture is transferred to a rotary evaporator. With constant stirring, the mixture was dried under reduced pressure of 10 hPa at 40° C. (using a hot water bath) for 1 hour to remove the organic solvent. After removal of the organic solvent, a powder with high fluidity is obtained.

While stirring in a rotary evaporator, the resulting powder was heated for 1 hour under a reduced pressure of 10 hPa at a temperature of 100° C. (using an oil bath), so as to polymerize and solidify the polymerizable monomer in the powder. As a result of drying, the surface of the aggregates of the spherical inorganic filler is coated with an organic polymer, and almost spherical particles of organic-inorganic composite fillers CF1 - CF16 (each in the amount of 9 g) are obtained, as indicated in Table 3 below.

Table 3

Composition and form of organic-inorganic composite filler The degree of addition of filler (wt.%) Average particle size (µm) Matrix (b1) Inorganic filler (b2) The form CF1 M1(100) PF1(300) wrong 75 thirty CF2 M1(100) PF2(300) wrong 75 28 CF3 M1(100) PF3(300) wrong 75 31 CF4 M1(100) PF4(300) wrong 75 24 CF5 M1(100) PF5(300) wrong 75 29 CF6 M1(100) PF5(233) wrong 70 28 CF7 M1(100) PF5(150) wrong 60 33 CF8 M1(100) PF5(400) wrong 80 31 CF9 M2(100) PF7(300) wrong 75 32 CF10 M1(100) PF8(300) wrong 75 29 CF11 M1(100) PF9(300) wrong 75 thirty CF12 M1(100) PF10(300) wrong 75 34 CF13 M1(100) PF11(300) wrong 75 28 CF14 M1(100) PF5(300) almost spherical 75 thirty CF15 M3(100) PF6(300) almost spherical 75 25 CF16 M2(100) PF7(300) almost spherical 75 32

In Table 3, the values in parentheses are parts by weight.

Examples 1 - 18

Add BPO at 0.5% by weight to the M1 or M2 matrices shown in Table 1 and mix to prepare a uniform polymerizable monomer composition. Then, the filler and inorganic particles (C) indicated in Table 2 and Table 3 are weighed and mixed with the matrix at the mixing ratio indicated in Table 4 and well dispersed using a planetary mixer to prepare a curable composition. The foam is removed from the composition under vacuum and filled into a mold (14 × 18 mm) to a height of 150 mm so as not to trap the foam, then the upper side is smoothed and, using a thermal pressure polymerization chamber, the composition is thermally polymerized under conditions of: pressure 3 kgf /cm2, temperature 120°C for 30 minutes. The cured composition is removed from the mold to form a resin block for dental milling. The characteristics of the resulting dental milling resin block were evaluated according to the above methods. Compositions and results are shown in Table 4, Table 5, and Table 6.

Comparative Examples 1 - 7, 9 and 10

Add BPO at 0.5% by weight to the M1, M2 or M3 matrices and mix to prepare a uniform polymerizable monomer composition. Then, the filler and inorganic particles (C) indicated in Table 2 and Table 3 are weighed and mixed with the matrix at the mixing ratio indicated in Table 4, and well dispersed using a planetary mixer to prepare a curable composition. The foam is removed from the composition under vacuum and filled into a mold (14 × 18 mm) to a height of 150 mm so as not to trap the foam, then the upper side is smoothed and, using a thermal pressure polymerization chamber, the composition is thermally polymerized under conditions of: pressure 3 kgf /cm2, temperature 120°C for 30 minutes. The cured composition is removed from the mold to form a resin block for dental milling. The characteristics of the resulting dental milling resin block were evaluated according to the above methods. Compositions and results are shown in Table 4, Table 5, and Table 6.

Comparative Example 8

Add BPO at 0.5% by weight to the M1 matrix and mix to prepare a uniform polymerizable monomer composition. Then the filler indicated in Table 2 and Table 3 is weighed and mixed with the matrix at the mixing ratio indicated in Table 4, then titanium dioxide (white pigment) is added to the composition in an amount of 0.04% by mass, pigment yellow (yellow pigment ) in the amount of 0.1% by mass, the pigment red (red pigment) in the amount of 0.09% by mass, and the pigment blue (blue pigment) in the amount of 0.06% by mass, and are well dispersed using a planetary mixer to prepare a curable compositions. The foam is removed from the composition under vacuum and filled into a mold (14 × 18 mm) to a height of 150 mm so as not to trap the foam, then the upper side is smoothed and, using a thermal pressure polymerization chamber, the composition is thermally polymerized under conditions of: pressure 3 kgf /cm2, temperature 120°C for 30 minutes. The cured composition is removed from the mold to form a resin block for dental milling. By visual evaluation, it is confirmed that the resin block has a hue (corresponding to A4) compatible with category A of high saturation hard resin teeth. Subsequently, the characteristics of the resin block are evaluated in accordance with the above methods. Compositions and results are shown in Table 4, Table 5 and Table 6.

In Table 4, the values in brackets for the resin matrix (A), spherical filler (B1), and organic-inorganic composite filler (B2), and the numerical value for organic particles (C) are parts by weight.

Table 6

Example No. Color tone compatibility Category A Category B low chroma model tooth high chroma model tooth low chroma model tooth high chroma model tooth Example 1 B2 B2 A2 A2 Example 2 B2 B1 A2 A1 Example 3 A1 A2 B1 B2 Example 4 A1 A1 B1 B1 Example 5 A1 A1 B1 B1 Example 6 A1 A1 B1 B1 Example 7 A1 A2 B1 B2 Example 8 A1 A1 B1 B1 Example 9 A1 A1 B1 B1 Example 10 A2 A2 B2 B2 Example 11 A1 A1 B1 B1 Example 12 A1 A2 A1 A2 Example 13 A1 A1 B1 B1 Example 14 A1 A1 B1 B1 Example 15 A1 A1 B1 A2 Example 16 A1 A2 A1 A2 Example 17 A1 A1 B1 B1 Example 18 A1 A1 B1 A1 comparative example 1 D D C C comparative example 2 D D C C Comparative Example 3 D D D D Comparative Example 4 B2 C C D Comparative Example 5 D D D D Comparative Example 6 B2 C C D Comparative Example 7 D D D D Comparative Example 8 C B1 D D Comparative Example 9 D D D D Comparative Example 10 D D D D

As understood from the results of Examples 1 to 18, the block of dental milling resin that satisfies the requirements of the present invention can exhibit colored light on a black background and has good color tone compatibility, and furthermore, it is shown that in the present invention there is a slight change over time in the color tone of the dental milling resin block.

As understood from the results of Comparative Examples 1 to 7, 9, and 10, it is known that the colored light from a dental milling resin block not meeting the requirements defined in the present invention is bluish on a black background (Comparative Examples 1 and 2: medium particle size of spherical filler < 230nm, Comparative Examples 9 and 10: resin matrix refractive index > refractive index of spherical filler) that the resin block does not express colored light (Comparative Example 3: Average particle size of spherical filler 80nm, Comparative Examples 5 and 7 : the filler has an irregular shape), that the colored light from the resin block is weak (Comparative Examples 4 and 6: the proportion of particles in the range of the average particle size of the spherical filler ± 5% is 88%), and that all such resin blocks have poor compatibility color tone with model teeth.

As understood from the results of Comparative Example 8, it is observed that when the spectral reflectance of a dental milling resin block that was obtained by adding a pigment to the composition of Comparative Example 3 in order to have an adjustable hue (hue compatible with category A of high chromaticity model teeth), measured on a black background and a white background using a colorimeter (from Tokyo Denshoku Co., Ltd., "TC-1800MKII"), the resin block exhibits spectral reflectance characteristics on a black background as well as on a white background. background, depending on the added pigment. The hue compatibility of the resin block with the hue corresponding to category A of high chroma model teeth is high, but the hue compatibility of the block with other model teeth is poor. In addition, the change in color tone of the resin block over time is large.

Claims (15)

1. A dental milling resin block containing a resin matrix (A), a spherical filler (B) whose average particle size ranges from 240 nm to 500 nm, and (C) inorganic particles having an average particle size of less than 100 nm, and which is such that at a thickness of 10 mm and when measured with a colorimeter, the lightness (V) is less than 5.0 and the saturation (C) is less than 2.0, these values being measured in the Munsell color system for colored light on black background and white background, and is such that at a thickness of 1 mm and when measured with a colorimeter, lightness (V) is less than 5.0 and saturation (C) is 0.05 or more, and these values are measured in the Munsell color system for colored light on a black background, but on a white background, lightness (V) is 6.0 or more and saturation (C) is less than 2.0, and these values are measured in the Munsell color system for colored light, in which the amount of spherical filler (B) is from 10 parts by weight to 1500 parts by weight relative to 100 parts by weight of the resin matrix (A), the amount of inorganic particles (C) is from 0.1 to 50 parts by weight relative to 100 parts by weight of the resin matrix (A) and in which 90% or more of the individual particles constituting the spherical filler (B) are in the range of the specified average particle size ± 5%, and the resin matrix (A) and the spherical filler (B) are each chosen to meet the requirement (X1) expressed by the following inequality (1): nP<nF (1), where nP is the refractive index of the resin matrix (A) at 25°C and nF is the refractive index of the spherical filler (B) at 25°C. 2. The dental milling resin block of claim 1, wherein the spherical filler (B) is an inorganic spherical filler (B). 3. Dental milling resin block according to claim 2, comprising an organic-inorganic composite filler (B2) which contains said inorganic spherical filler (B). 4. Dental milling resin block according to claim 3, comprising a powdered spherical filler (B1) consisting of said spherical filler (B) and said organic-inorganic composite filler (B2). 5. A method for producing a resin block for dental milling, which contains a resin matrix (A), a spherical filler (B) whose average particle size is in the range of 240 nm to 500 nm, and (C) inorganic particles having an average particle size particles smaller than 100 nm; the method includes polymerizing a curable composition that contains a polymerizable monomer, a spherical filler (B) having an average particle size in the range of 240 nm to 500 nm, (C) inorganic particles having an average particle size of less than 100 nm, and a polymerization initiator, and in which 90% or more of the individual particles constituting the spherical filler (B) are in the range of the specified average particle size ± 5%, and each of the polymerizable monomer and the spherical filler (B) is selected so as to meet the requirement (X2) expressed the following inequality (2): nPm<nF (2), where nP is the refractive index at 25°C of the polymer obtained by polymerizing the polymerizable monomer, and nF is the refractive index of the spherical filler (B) at 25°C; and wherein the dental milling resin block is such that, at a thickness of 10 mm and as measured by a colorimeter, the lightness (V) is less than 5.0 and the saturation (C) is less than 2.0, these values being measured in the color system Munsell for colored light on a black background and on a white background, and is such that at a thickness of 1 mm and when measured with a colorimeter, the lightness (V) is less than 5.0 and the saturation (C) is 0.05 or more, and these values measured in the Munsell color system for colored light on a black background, but on a white background, the lightness (V) is 6.0 or more and the saturation (C) is less than 2.0, and these values are measured in the Munsell color system for colored light, wherein the amount of the spherical filler (B) is from 10 parts by weight to 1500 parts by weight relative to 100 parts by weight of the resin matrix (A), and the amount of inorganic particles (C) is from 0.1 to 50 parts by weight relative to 100 parts by weight of the resinous matrix (A).