JP7018257B2 - How to make a hardened dental resin - Google Patents

Description

The present invention relates to a method for producing a cured dental resin. More specifically, the present invention relates to a hardened dental resin used for producing dental prostheses such as inlays, onlays, crowns, bridges, molar / anterior tooth veneers, and implant superstructures by cutting with a CAD / CAM device. It is related to the manufacturing method.

Dental prostheses such as inlays that are manually produced by dental technicians may have variations in the quality of the finished dental prostheses depending on the skills and proficiency of the dental technicians. Instead of manually producing a dental prosthesis by a dental technician, a block-shaped or other hardened dental resin has been cut into a dental prosthesis using a CAD / CAM device. Therefore, the dental prosthesis suitable for the patient can be quickly provided without any variation in quality.
In Patent Document 1, a paste-like uncured material to be a dental resin block is injected into a concave mold made of polypropylene or the like, and the concave mold and the uncured material are placed in a container capable of having a predetermined pressure as a whole. A method has been proposed in which a dental resin block that can be cut by a CAD / CAM device with few cracks and bubbles is manufactured by pressurizing at 1.0 MPa or more and heating at 60 ° C. or higher in that state to polymerize and cure. ing.

JP-A-2015-97854

According to this method, a dental resin block having few cracks and bubbles can be obtained, but color unevenness related to the aesthetics of a dental prosthesis cannot be solved.
Such a paste-like material before curing has a (meth) acrylate-based polymerizable monomer as a liquid component and an inorganic filler as a powder component (inorganic filler), and the inorganic filler is covered with the liquid component. The paste-like pre-cured material that is in a state and when injected is the inside where the liquid component and the inorganic filler are uniformly mixed, and the past-like pre-cured material in which the liquid component has exuded. Form a membranous surface that encloses.
When injecting a significant amount of paste-like uncured material into an acceptable sized concave mold, the paste-like uncured material to be injected accompanies the injection of the paste-like uncured material in the concave mold. It is sequentially injected until a predetermined amount is reached, while being folded, spread laterally, and further injected on top of it. At this time, as described above, the paste-like material before curing when injected is the inside where the liquid component and the inorganic filler are uniformly mixed, and the paste-like material before curing in which the liquid component is exuded. Because it forms a membranous surface that encloses the material of the material, it remains as a complex trace of injection (ie, non-uniformity of liquid components and inorganic fillers), which in turn leads to uneven coloration of the hardened dental resin. it is conceivable that. This can be more pronounced when the inorganic filler imparts thixotropic properties to the paste-like uncured material.
Therefore, a uniform dental resin cured product used for producing a dental prosthesis by cutting with a CAD / CAM device is desired without bubbles or color unevenness.

This invention was devised as a result of diligent research in view of the above circumstances, and a large number of dental prostheses are machined by a CAD / CAM device while maintaining a uniform disc-like form without bubbles or color unevenness. It is an object of the present invention to provide a manufacturing method capable of obtaining a disc-shaped dental resin cured product having a size capable of being obtained.

In order to solve the above problems, the present invention is (1) a method for producing a dental resin cured product before cutting out a shape, in which an inorganic filler is added to a liquid component to be the dental resin cured product. The stirring comprises a step of injecting and stirring the paste-like material before curing into a concave container and a step of heating the material before curing together with the concave container in an atmosphere of 90 ° C. or higher and curing the material. Stirring is performed by giving the concave container at least a rotation about an inclined axis toward an obliquely upward direction, and the concave container is kept in a disk shape, and a large number of dental prostheses are formed by a CAD / CAM device. It is characterized by being a bottomed cylindrical container for molding a disk-shaped dental resin cured product having a size that can be machined .
(2) In the above (1), the step of injecting and stirring the paste-like uncured material to be the dental resin cured product into the concave container is agitated while injecting the uncured material into the concave container. It may be a process.
Here, "stirring while injecting the material before curing into the concave container" means that the injection and stirring of the material before curing are started at the same time and the stirring is continued even after the injection is completed. It means that stirring is started from the middle of injection and stirring is continued even after the injection is completed.
(3) In the above (1), the step of injecting and stirring the paste-like uncured material to be the dental resin cured product into the concave container is completed by injecting the uncured material into the concave container. It may be a step of stirring later.
(4) In the above (3), it is preferable that the stirring is performed by giving rotation and revolution to the concave container.
(5) In the above (1), (2), (3) or (4), the liquid component is a methacrylate compound or an acrylate compound, and the average particle size of the inorganic filler is 0.01 μm or more and 2 μm or less. Is preferable .
Therefore , the "disc-shaped dental resin cured product" here means a size that can cut a large number of dental prostheses with a CAD / CAM device while maintaining the disc-shaped form.

Since the present invention is configured as described above, it has the effects described below.
That is, it is possible to cut a large number of dental prostheses with a CAD / CAM device while keeping the paste-like uncured material in which an inorganic filler is mixed with a liquid component to be a dental resin cured product in a disk-like form. In the process of injecting and stirring into a bottomed concave container for molding a disk-shaped dental resin cured product of a size , stirring is performed by giving the concave container at least a rotation around an inclined axis toward diagonally upward. Therefore, even if air bubbles are entrained or color unevenness occurs due to injection, the air bubbles entrained by stirring will be defoamed and the color unevenness will be eliminated. By heating and curing in an atmosphere of 90 ° C. or higher, a homogeneous dental resin cured product without bubbles or color unevenness can be obtained quickly, reliably and easily.
A dental resin cured product having uneven color is inferior in aesthetics, and the residual air bubbles not only impairs aesthetics but also causes a decrease in strength. For example, a high-strength dental resin cured product can be obtained that is homogeneous, has no bubbles or uneven color.
More specifically, the hardened dental resin in which air bubbles remain cannot obtain the strength required for the dental prosthesis due to a decrease in strength and the like, and when cutting with a CAD / CAM device, chipping is performed. If a machined dental prosthesis is used in the oral cavity, it may cause chipping or breakage. The required strength for the prosthesis is obtained and no chipping or cracking occurs when cut by a CAD / CAM device and therefore the machined dental prosthesis is chipped for a long time even when used in the oral cavity. Do not break or break.
In addition, the hardened dental resin having uneven color is not only inferior in aesthetics when used as a dental prosthesis, but also the residual air bubbles impairs the aesthetics when used as a dental prosthesis. Since the dental resin cured product obtained by the invention is uniform without color unevenness and air bubbles, it is possible to obtain a dental prosthesis with good aesthetics.

It is a conceptual diagram which shows an example of the stirring method in this invention, and (a) is the explanation that the paste-like material before hardening is agitated by rotating about the inclined axis which the concave container goes diagonally upward. Yes, (b) is an explanation from the opening side of the concave container. It is a conceptual diagram which shows the other example of the stirring method in this invention, and (a) is (B) is an explanation from the opening side of the concave container. In order to mount the concave container used in the examples and comparative examples of the present invention on a rotating and revolving stirrer that rotates and revolves around an inclined axis extending diagonally upward, the concave container is incorporated between the lower adapter and the upper adapter. , It is a conceptual diagram explaining that the material before curing is agitated in the form of a paste, which is attached in that state.

Hereinafter, embodiments for carrying out the present invention will be described in more detail. Of course, the present invention is not limited to the following embodiments.
As the paste-like non-curing material that becomes the dental resin cured product, a methacrylate compound or an acrylate compound that has been widely used in dental materials can be used (hereinafter, these are referred to as "liquid component" or "monomer"). Sometimes.).
Examples of the methacrylate compound or acrylate compound include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxy-1,3-dimethacryloxypropane, n-butyl methacrylate, and isobutyl methacrylate. Tetrahydrofurfuryl methacrylate, glycidyl methacrylate, 2-methoxyethyl methacrylate, 2-ethylhexyl methacrylate, benzyl methacrylate, phenyl methacrylate, phenoxyethyl methacrylate, 2,2-bis (methacryloxyphenyl) propane, 2,2-bis [4- ( 2-Hydroxy-3-methacryloxypropoxy) phenyl] propane, 2,2-bis (4-methacryloxydiethoxyphenyl) propane, 2,2-bis (4-methacryloxypolyethoxyphenyl) propane, ethylene glycol dimethacrylate , Diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, butylene glycol dimethacrylate, neopentyl glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, tri Methylolethane trimethacrylate, trimethylolethanetrimethacrylate, pentaerythritol trimethacrylate, trimethylolmethanetrimethacrylate, pentaerythritol tetramethacrylate, di-2-methacryloxyethyl-2,2,4-trimethylhexamethylene dicarbamate, 1,3 , 5-Tris [1,3-bis (methacryloyloxy) -2-propoxycarbonylaminohexane] -1,3,5- (1H, 3H, 5H) triazine-2,4,6-trione and acrylates thereof. It can be exemplified. These methacrylates and acrylates can be used alone or in admixture as needed.

Further, as the catalyst for polymerizing the compound, an organic peroxide, an azo compound or the like can be used.
Specifically, benzoyl peroxide, ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxyester, peroxydicarbonate, 2,2'-azobisisobutyronitrile, 2,2'-Azobis-2,4-dimethylvaleronitrile, 4,4'-azobis-4-cyanovaleric acid, 1,1'-azobis-1-cyclohexanecarbonitrile, dimethyl-2,2'-azo Examples thereof include bisisobutyrate, 2,2'-azobis- (2-aminopropane) dihydrochloride, and these can be used alone or in combination.

A filler is added to the paste-like material before curing . As the filler, an inorganic filler having an average particle size of 0.01 μm or more and 2 μm or less can be adopted. Colloidal silica is generally used as an inorganic filler having an average particle size of 0.01 μm or more and 0.04 μm or less. An average particle size of 0.016 μm) or the like can be used. Silica beads and crushed glass powder are generally used as the inorganic filler having an average particle size of 0.04 μm or more and 2 μm or less, and the composition thereof is not particularly limited, but quartz glass, aluminosilicate glass, and X. Glass containing alkaline earth metal atoms such as calcium, strontium, and barium, which is a glass having line contrast properties, zinc glass, lead glass, and the like are suitable. It is desirable that the surface of these inorganic fillers be treated with silane treatment, and usually, an organosilicon compound such as γ-methacryloxypropyltrimethoxysilane is used as a surface treatment agent and silaneized by a usual method.
The content of the inorganic filler having an average particle size of 0.01 μm or more and 0.04 μm or less is preferably 0.1 part by weight to 2 parts by weight with respect to 100 parts by weight of the liquid component. If it is less than 0.1 part by weight, it is difficult to obtain a sufficient thickening effect, and if it exceeds 2 parts by weight, the paste-like material before curing at the time of producing the dental resin cured product becomes hard, and bubbles are formed in the dental resin cured product. Is not preferable because it is easy to mix. The content of the inorganic filler having an average particle size of 0.04 μm or more and 2 μm or less is preferably 1 part by weight to 400 parts by weight with respect to 100 parts by weight of the liquid component. If it is less than 1 part by weight, it is difficult to obtain sufficient wear resistance, and if it exceeds 400 parts by weight, the paste-like material before curing at the time of producing the cured dental resin becomes hard, and air bubbles are mixed in the cured dental resin. It becomes easy and is not preferable.

For the paste-like material before curing, an inorganic filler having an average particle size of 0.01 μm or more and 2 μm or less is mixed with at least one unsaturated double bond-containing methacrylate or acrylate monomer, cured, and pulverized to obtain an average. An organic-inorganic composite filler adjusted to have a particle size of 5 μm or more and 50 μm or less can be contained in place of a part of the above-mentioned inorganic filler.
When the organic-inorganic composite filler is contained, the content is preferably 1 part by weight to 67 parts by weight with respect to 100 parts by weight of the liquid component. If it is less than 1 part by weight, the effect of improving the surface smoothness and the wear resistance is not recognized, and if it exceeds 67 parts by weight, the mechanical strength is lowered, which is not preferable.
The average particle size here is measured by a laser diffraction / scattering type particle size distribution measuring device (trade name; Partica LA-950V2) manufactured by HORIBA, Ltd.

In addition, a trace amount of an ultraviolet absorber, a colorant, a polymerization inhibitor and the like may be used, if necessary.

As a concave container for stirring the paste-like material before curing, there is no problem in rotating around the inclined axis toward diagonally upward, and the paste-like material before curing is smoothly agitated in the concave container. It is preferable that the paste-like uncured material is polymerized and cured in the concave container after stirring to obtain a dental resin cured product, and a bottomed cylindrical container is exemplified. It is not limited to this.
The concave container may have no lid and may be open upward, or may have a lid.
The concave container has a size in which a paste-like uncured material is polymerized and cured in the concave container to obtain a disk-shaped dental resin cured product .
According to the disk-shaped dental resin cured product, a large number of dental prostheses can be continuously cut by a CAD / CAM device while maintaining the disk-shaped form, which has advantages such as improvement in productivity. ..
As the material of the concave container, a thermoplastic resin or a silicone resin can be adopted. Of course, it may be metal.

In order to stir the paste-like uncured material in the concave container, for example, a method of giving the concave container 1 a rotation about an inclined axis 2 diagonally upward can be adopted as shown in FIG. 1 (a). ..
According to this, when the concave container 1 is given a rotation about the inclined axis 2 upward, as shown in FIG. 1 (b), the concave container is connected to the concave container from the lower retention portion with the rotation of the concave container 1. It is lifted upward along the inner surface of 1, a part of which descends from the middle toward the lower retention part as shown by arrow A, and the rest is shown by arrow B with the rotation of the concave container 1. By returning to the retention portion as described above, the paste-like material 3 before curing is stirred. As a result, the non-uniform parts of the liquid component and the inorganic filler in the paste-like uncured material disappear with the injection to eliminate the color unevenness, and the entrained air bubbles burst on the surface or the wall surface of the concave container. Then, it disappears and the paste-like material before curing is homogenized.
As a device for rotating the concave container 1 by a motor or the like around an inclined axis 2 diagonally upward, for example, a tube rotator manufactured by AS ONE Corporation may be adopted and the concave container 1 may be attached to the rotating shaft thereof. ..
Needless to say, the concave container 1 may be manually rotated about the inclined axis toward the diagonally upward direction.
According to the method of giving the concave container 1 a rotation centered on the inclined axis 2 diagonally upward as shown in FIG. 1, the paste-like material before curing can be stirred while being injected into the concave container 1.
The angle of the inclined axis 2 diagonally upward is preferably 45 to 80 ° so that the paste-like material before curing easily descends in the concave container 1 due to gravity.
The rotation speed of the concave container 1 is preferably 10 to 60 rpm.
The stirring by rotation may be performed under reduced pressure.

In order to stir the paste-like material before curing in the concave container, the concave container 11 as shown in FIG. 2 (a) is given rotation around the inclined axis 12 diagonally upward, and the concave container 11 is placed. A method of revolving may be adopted.
According to this, when the concave container 11 is given a rotation about the inclined axis 12 upward and the concave container 11 is revolved, the paste-like material 13 before curing is accompanied by the rotation of the concave container 11. The generated centrifugal force and the centrifugal force generated by the revolution work, and as shown in FIG. 2A, the flow descends along the wall surface of the concave container 11 and the flow from the bottom to the top along the inclined axis direction moves up and down. Along with the generation of the convection C, the vortex flow E is also generated as shown in FIG. 2 (b), and the paste-like material before curing is efficiently stirred. As a result, non-homogeneous parts of the liquid component and the inorganic filler in the paste-like uncured material generated by the injection disappear and the color unevenness is eliminated, and the entrained air bubbles are discharged on the surface or the wall surface of the concave container. It ruptures and disappears, and the paste-like material before curing is homogenized.
The stirring by rotation and revolution may also be performed under reduced pressure.
As a device for rotating the concave container by a motor or the like around an inclined axis diagonally upward, for example, a rotating and revolving stirrer (trade name; Hi-Major series) manufactured by Sugino Machine Limited can be adopted.
Needless to say, the concave container may be rotated around the inclined axis toward diagonally upward and revolved manually.
The angle of the inclined axis 12 toward diagonally upward, the rotation speed and the revolution speed of the concave container 11 are appropriately selected depending on the injection amount and viscosity of the paste-like material before curing, the revolution radius, etc., but the angle of the inclined axis Is preferably 40 to 50 °, a rotation speed of 300 to 1000 rpm, and a revolution speed of 700 to 1200 rpm.

After stirring is completed, the paste-like uncured material is heated together with the concave container in an atmosphere of 90 ° C. or higher and cured to obtain a homogeneous dental resin cured product without bubbles or color unevenness.
If the heating temperature is less than 90 ° C., the polymerization rate is remarkably lowered, so that unpolymerized monomers tend to remain, and the desired mechanical strength cannot be obtained, which is not preferable.
In order to shorten the polymerization time and improve the productivity, it is preferable to heat at 100 ° C. or higher.
The heating atmosphere may be a heating atmosphere under atmospheric pressure, or may be a heating atmosphere under pressure exceeding atmospheric pressure.
Incubators, electric furnaces, dryers, etc. can be used for heating under atmospheric pressure.
An autoclave or the like can be used for heating under pressure exceeding atmospheric pressure.
Furthermore, an electric furnace that can control the atmosphere under atmospheric pressure, or an autoclave under pressure exceeding atmospheric pressure is used to significantly reduce the oxygen concentration in the heating atmosphere and in a heating atmosphere of 100 ° C or higher before curing the paste. When the material is polymerized and cured, polymerization inhibition by oxygen does not occur, so that the residual unpolymerized monomer can be further reduced.

Next, an example will be shown together with a comparative example and will be described in more detail. Of course, the present invention is not limited to the following examples.
(Example 1)
Urethane dimethacrylate (UDM) 50% by weight, 2,2-bis (4-methacryloxypolyethoxyphenyl) propane (Bis) in a concave container having a diameter of 100 mm and a depth of 30 mm obtained by vacuum forming a polypropylene sheet having a thickness of 1 mm. -Average granules treated with a monomer consisting of 30% by weight of MEPP and 20% by weight of triethylene glycol dimethacrylate (TEGDMA), benzoyl peroxide (BPO) as a polymerization initiator, and γ-methacryloxypropyltrimethoxysilane as an inorganic filler. Using a glass filler having a diameter of 0.7 μm, 250 g of the prepared paste-like material before curing was injected into 100 parts by weight of the monomer, 0.4 parts by weight of the polymerization initiator, and 200 parts by weight of the inorganic filler.
The average particle size of the glass filler here is measured by a laser diffraction / scattering type particle size distribution measuring device (trade name; Partica LA-950V2) manufactured by HORIBA, Ltd.
When the paste-like uncured material poured into the concave container was visually observed from above, bubbles and color unevenness were observed.
As shown in FIG. 3, the concave container 21 in which the paste-like material 20 before curing is injected is incorporated between the lower adapter 22 and the upper adapter 23, and in this state, it is used in a rotating and revolving stirrer manufactured by Sugino Machine Limited. The material was attached and the paste-like material before curing was stirred for 120 seconds at a revolution speed of 1090 rpm and a rotation speed of 970 rpm.
The lower adapter 22 and the upper adapter 23 are made of polypropylene.
When the paste-like material before curing after stirring was visually observed from above, no bubbles or color unevenness were observed.
After the stirring was completed, the upper adapter was removed, and the concave container containing the paste-like material before curing was taken out from the lower adapter.
In the case of the concave container shown in FIG. 3, the upper adapter and the lower adapter are adopted, but in the case of the concave container shown in FIG. 2, the upper adapter and the lower adapter are not always required.
The paste-like uncured material stirred together with the concave container was placed in an autoclave manufactured by Kyoshin Engineering Co., Ltd., and the pressure in the furnace was increased to 4.0 MPa with nitrogen having a concentration of 99.9%, and the pressure inside the furnace was increased to 4.0 MPa. The temperature was raised to 120 ° C. and held for 60 minutes for polymerization and curing. Then, the temperature in the furnace was lowered to 45 ° C. or lower, the pressure was lowered to atmospheric pressure, the cured product was taken out from the autoclave together with the concave container, and then the cured product was taken out from the concave container. The obtained cured product had a disk shape having a diameter of 100 mm and a thickness of 16 mm.
The obtained cured product could be processed into a dental CAD / CAM disc shape having a thickness of 14 mm and a grip portion diameter of 98 mm that could be gripped by a dental milling machine manufactured by GC Corporation using an NC lathe. ..

(Example 2)
In Example 1, the equipment required for polymerization curing was a blower constant temperature dryer manufactured by Yamato Kagaku Co., Ltd., and a cured product was prepared under the same conditions as in Example 1 except that the atmosphere for polymerization curing was air and the pressure was atmospheric pressure. did. The obtained cured product had a disk shape having a diameter of 100 mm and a thickness of 16 mm.

(Comparative Example 1)
A cured product was prepared under the same conditions as in Example 1 except that the stirring step was not performed in Example 1. The obtained cured product had a disk shape having a diameter of 100 mm and a thickness of 16 mm.

(Comparative Example 2)
A cured product was prepared under the same conditions as in Example 1 except that the polymerization temperature was set to 80 ° C. in Example 1. The obtained cured product had a disk shape having a diameter of 100 mm and a thickness of 16 mm.

Table 1 shows the manufacturing conditions of the above Examples and Comparative Examples.

The following tests were performed on the cured products obtained in Examples and Comparative Examples.
<Color unevenness, bubbles>
The color unevenness on the surface of the cured product taken out from the concave container and the presence or absence of air bubbles were visually observed.
<Bending strength>
In accordance with JIS T6120, the cured product was cut into 14 mm x 4 mm x 1.2 mm, and the surface was polished with # 1000 SiC abrasive paper to obtain a test piece, and an autograph (model; AG-5KNXplus, Shimadzu Corporation) was obtained. A 3-point bending test was performed with a distance between fulcrums of 12 mm and a crosshead speed of 1 mm / min.
The number of sample pieces of the test piece in the bending test was 5, and the strength was an average value.
The results are shown in Table 2.

1,11,21 Concave container

Claims (5)

It is a method of manufacturing a dental resin cured product before cutting out the shape.
A step of injecting and stirring a paste-like uncured material in which an inorganic filler is mixed with a liquid component to be a dental resin cured product into a concave container.
A step of heating the uncured material together with the concave container in an atmosphere of 90 ° C. or higher to cure the material.
Including
The stirring is performed by giving the concave container a rotation about at least an inclined axis toward an obliquely upward direction .
The concave container is a bottomed cylindrical container for molding a disk-shaped dental resin cured product having a size capable of cutting a large number of dental prostheses with a CAD / CAM device while maintaining the disk-shaped form. A method for producing a hardened dental resin. The claim is characterized in that the step of injecting and stirring the paste-like uncured material to be the dental resin cured product into the concave container is a step of stirring while injecting the uncured material into the concave container. 1. The method for producing a hardened dental resin according to 1. The step of injecting and stirring the paste-like uncured material to be the dental resin cured product into the concave container is a step of injecting the uncured material into the concave container and stirring after the injection is completed. The method for producing a cured dental resin according to claim 1. The method for producing a cured dental resin according to claim 3, wherein the stirring is performed by giving rotation and revolution to the concave container. The liquid component is a methacrylate compound or an acrylate compound, and the liquid component is
The method for producing a cured dental resin according to claim 1, 2, 3 or 4 , wherein the average particle size of the inorganic filler is 0.01 μm or more and 2 μm or less .

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