JP7010469B2 - Materials for denture bases, denture bases and methods for manufacturing them, and dentures with beds and methods for manufacturing them. - Google Patents

Description

The present invention relates to a material for a denture base, a denture base and a method for manufacturing the same, and a denture with a floor and a method for manufacturing the same.

Conventionally, a denture provided with an artificial tooth and a denture base for fixing the artificial tooth has become widespread. As the denture base, a denture base containing a polymer is widely used.
The artificial tooth bed containing a polymer is produced by a method in which a curable resin is poured into a plaster mold composed of an upper mold and a lower mold, and then the curable resin is cured (for example, photopolymerization, thermosetting, etc.). rice field.
In recent years, there is also known a method of producing the artificial tooth bed by cutting a cured polymer (resin) using, for example, a CAD (Computer Aided Design) / CAM (Computer Aided Manufacturing) system (for example). See Patent Documents 1 and 2).

International Publication No. 2010/08822 Pamphlet Japanese Patent Publication No. 2006-521136

By the way, when a denture having a denture base containing a polymer is used for a long period of time, the denture base may break. According to the study of the present inventor, the susceptibility to fracture of the denture base correlates with the durability of the denture base (yield strength of the compression test), and the durability of the denture base (yield strength of the compression test). It was found that the higher the value, the less likely it is that the denture base will break.
On the other hand, considering the workability in producing the denture base and the practicality of the denture having the denture base, it is desirable to use a hard material as the material for the denture base.

The present invention has been made in view of the above, and an object of the present invention is to achieve the following object.
That is, an object of the present invention is to provide a material for a denture base which is excellent in hardness (flexural modulus) and durability when used as a denture base (yield point strength in a compression test).
Another object of the present invention is to provide a denture base which can be manufactured by using a denture base material having excellent hardness (flexural modulus) and which has excellent durability (yield point strength of compression test) and a method for manufacturing the denture base. It is to be.
Further, an object of the present invention is to provide a denture base which can be manufactured by using a denture base material having excellent hardness (flexural modulus) and which has excellent durability (yield point strength of compression test) for a long period of time. It is an object of the present invention to provide a denture having a floor and a method for manufacturing the same, which can suppress the breakage of the denture base due to use.

Specific means for achieving the above-mentioned problems are as follows.

<1> Contains a polymer component including an acrylic resin,
Flexural strength measured by a three-point bending test with a test speed of 2 mm / min and a distance between fulcrums of 64 mm, in accordance with JIS K7171 (2008), when a test piece with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm is used. Is 110 MPa or more,
Maximum stress intensity measured by fracture toughness test by bending test under JIS T6501 (2012) with test speed of 1 mm / min when a notched test piece with a length of 39 mm, a height of 8 mm and a width of 4 mm is used. A material for artificial dentition with a coefficient of 1.9 MPa · m ^1/2 or more and a total destruction work of 900 J / m ² or more.
<2> The material for a denture base according to <1>, wherein the bending strength is 200 MPa or less.
<3> The material for a denture base according to <1> or <2>, wherein the maximum stress intensity factor is 3.5 MPa · m ^1/2 or less and the total fracture work is 2500 J / m ² or less.
<4> When a test piece with a single notch having a length of 80 mm, a width of 10 mm, a remaining width of 8 mm, and a thickness of 4 mm is provided with a notch of shape A specified in JIS K7111-1 (2012), JIS K7111 -1 (2012) is described in any one of <1> to <3>, wherein the impact strength measured by the Charpy impact test under the condition of edgewise impact is 1.6 kJ / m ² or more. Material for prosthesis.
<5> The material for a denture base according to any one of <1> to <4>, wherein the polymer component has a weight average molecular weight of 1.2 million or more.
<6> The material for a denture base according to any one of <1> to <5>, wherein the polymer component further contains rubber.
<7> The material for a denture base according to <6>, wherein the rubber contains a graft polymer obtained by graft-polymerizing a rubber-like polymer having a crosslinked structure with a thermoplastic resin component.
<8> The material for a denture base according to <6> or <7>, wherein the rubber contains a graft polymer obtained by graft-polymerizing a thermoplastic resin component onto a butadiene-based (co) polymer.
<9> The denture base material according to any one of <6> to <8>, wherein the content of the rubber is 1% by mass or more and 10% by mass or less with respect to the total amount of the denture base material.
<10> The material for a denture base according to any one of <1> to <9>, wherein the content of the acrylic resin is 90% by mass or more with respect to the total amount of the material for the denture base.
<11> The material for a denture base according to any one of <1> to <10>, wherein the acrylic resin is a polymer containing 95% by mass or more of a structural unit derived from a monofunctional acrylic monomer. ..
<12> The material for a denture base according to <11>, wherein the monofunctional acrylic monomer is at least one monomer selected from the group consisting of methacrylic acid and methacrylic acid alkyl esters.
<13> The monofunctional acrylic monomer comprises methacrylic acid and methacrylic acid alkyl ester.
The material for a denture base according to <11>, wherein the amount of the methacrylic acid with respect to the total amount of the methacrylic acid and the methacrylic acid alkyl ester is 0.1% by mass or more and 15% by mass or less.
<14> The material for a denture base according to any one of <1> to <13>, wherein the acrylic resin is a copolymer of methacrylic acid and methyl methacrylate.
<15> A denture base containing the material for the denture base according to any one of <1> to <14>.
<16> A denture having a denture including the denture base according to <15> and an artificial tooth fixed to the denture base.
<17> A method for manufacturing a denture base, which comprises a cutting step of cutting the material for the denture base according to any one of <1> to <14> to obtain a denture base.
<18> A cutting process for obtaining a denture base by cutting the material for the denture base according to any one of <1> to <14>.
The fixing step of fixing the artificial tooth to the denture base and
A method for manufacturing a denture with a floor.

In the present specification, the numerical range represented by using "-" means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.
Further, in the present specification, the yield point strength of the compression test may be simply abbreviated as "yield point strength". That is, in the present specification, the term "yield point strength" simply means the yield point strength of the compression test.

According to the present invention, there is provided a material for a denture base which is excellent in hardness (flexural modulus) and durability when used as a denture base (yield point strength in a compression test).
Further, according to the present invention, there is provided a denture base and a method for manufacturing the denture base, which can be manufactured by using a material for a denture base having excellent hardness (flexural modulus) and having excellent durability (yield point strength of compression test). Will be done.
Further, according to the present invention, the denture base can be manufactured by using a material for a denture base having excellent hardness (flexural modulus), and has a denture base having excellent durability (yield point strength of compression test) for a long period of time. Provided are a denture with a floor capable of suppressing breakage of the denture base due to use and a method for manufacturing the denture.

It is a perspective view which conceptually shows an example of the denture with a floor of this invention. It is a graph which shows the relationship between the minute maximum stress intensity factor of a denture base and the maximum stress intensity factor of a material for a denture base in one example of this invention. It is a graph which shows the relationship between the minute total destruction work of a denture base and the total destruction work of a material for a denture base in one example of the present invention.

[Material for denture base]
The material for the artificial tooth bed of the present embodiment contains a polymer component containing an acrylic resin, and when a test piece having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm is used, the test conforms to JIS K7171 (2008). When the bending strength measured by the three-point bending test under the conditions of a speed of 2 mm / min and a distance between fulcrums of 64 mm is 110 MPa or more, and a notched test piece having a length of 39 mm, a height of 8 mm, and a width of 4 mm is used, JIS The maximum stress intensity factor measured by the fracture toughness test by the bending test under the condition of test speed of 1 mm / min according to T6501 (2012) is 1.9 MPa · m ^1/2 or more, and the total fracture work is 900 J. / M ² or more.
According to the material for the denture base of the present embodiment, the hardness (flexural modulus) is excellent. Therefore, it is possible to manufacture a denture base having excellent hardness (bending elastic modulus), and it is good in practicality of a denture having a denture base and workability when manufacturing the denture base.
Further, according to the material for the denture base of the present embodiment, the durability (yield point strength of the compression test) when the denture base is used is improved. This suppresses the breakage of the denture base due to long-term use. The reason for this is not clear, but it is presumed as follows.
That is, the shape of the denture base is a complicated shape that matches the oral cavity of the denture user. Therefore, the force applied to the denture by occlusal is locally concentrated on a part of the denture base, and as a result, even when a hard material (material having a high elastic modulus) is used as the material for the denture base. , It is considered that the denture base may be broken. Further, if a fine crack is generated in the denture base for some reason during use, it is considered that the denture base is likely to break from the crack as a starting point.
Regarding these points, as a material for artificial dentition, it is not only a "hard material" (a material with a high elastic modulus), but also has high durability against a force applied from multiple directions, or a force is applied from multiple directions. By using a material that is less prone to cracking, that is, a material that has high bending strength in a three-point bending test, maximum stress expansion coefficient in a fracture toughness test, and total fracture work, durability when used as a prosthesis base ( It is considered that the yield point strength) can be improved and, by extension, the fracture of the prosthesis base when the bed prosthesis is used for a long period of time can be suppressed.

The material for the denture base of the present embodiment has a test speed of 2 mm / min according to JIS K7171 (2008) when a test piece having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm (80 mm × 10 mm × 4 mm size) is used. The bending strength measured by the three-point bending test under the condition that the distance between the fulcrums is 64 mm is 110 MPa or more.

The test piece can be collected from the material for the denture base of the present embodiment by a method such as cutting. In the following, "flexural strength in a three-point bending test" may be simply referred to as "flexural strength".
When the bending strength of the denture base material is 110 MPa or more, the durability (yield point strength of the compression test) is remarkably improved and the hardness (bending elastic modulus) is excellent when the denture base is used.
The bending strength can be measured by using, for example, a 5-bending tester 2001-5 manufactured by Intesco.

The upper limit of the bending strength in the present embodiment is not particularly limited, but from the viewpoint of machinability, the bending strength is preferably 200 MPa or less.

The denture base material of the present embodiment is subjected to a bending test under a test speed of 1 mm / min according to JIS T6501 (2012) when a notched test piece having a length of 39 mm, a height of 8 mm and a width of 4 mm is used. The maximum stress intensity factor measured by the fracture toughness test is 1.9 MPa · m ^1/2 or more, and the total fracture work is 900 J / m ² or more.

The test piece can be collected from the material for the denture base of the present embodiment by a method such as cutting. In the following, the "maximum stress intensity factor in the fracture toughness test" may be simply referred to as the "maximum stress intensity factor", and the "total fracture work in the fracture toughness test" may be simply referred to as the "total fracture work".
When the maximum stress intensity factor of the denture base material is 1.9 MPa · m ^1/2 or more and the total fracture work is 900 J / m ² or more, the toughness of the denture base is improved and the denture base is improved. Durability (yield point strength of compression test) is improved.
The upper limit of the maximum stress intensity factor is not particularly limited, but from the viewpoint of balancing with hardness (flexural modulus), the upper limit is preferably, for example, 4.0 MPa · m ^1/2 or less, 3 It is more preferably 7. MPa · m ^1/2 or less, and further preferably 3.5 MPa · m ^1/2 or less.
The upper limit of the total fracture work is not particularly limited, but from the viewpoint of balancing with hardness (flexural modulus), the upper limit is preferably, for example, 3000 J / m ² or less, and 2500 J / m ² . It is more preferably less than or equal to 2000 J / m ² or less.
The maximum stress intensity factor and total fracture work can be measured using, for example, a universal testing machine 210X manufactured by Intesco.

The artificial tooth bed material of the present embodiment is a test piece with a single notch having a length of 80 mm, a width of 10 mm, a remaining width of 8 mm, and a thickness of 4 mm, provided with a notch having a shape A specified in JIS K7111-1 (2012). The impact strength measured by the Charpy impact test under the conditions of edgewise impact according to JIS K7111-1 (2012) is preferably 1.6 kJ / m ² or more, and the impact resistance ( From the viewpoint of significantly improving the fracture weight of the falling ball test), it is more preferably 2.64 kJ / m ² or more, and further preferably 2.70 kJ / m ² or more.

The test piece with a single notch can be collected from the material for the denture base of the present embodiment by a method such as cutting.
When the impact strength is 1.6 kJ / m ² or more, the impact resistance (break weight of the falling ball test) when the denture base is used is improved.
In particular, when the impact strength exceeds 2.64 kJ / m ² (preferably 2.70 kJ / m ² or more), the impact resistance (break weight of the falling ball test) when the denture base is used is significantly improved.
The upper limit of the impact strength is not particularly limited, but the upper limit can be, for example, 6.0 kJ / m ² or less.
The impact strength can be measured, for example, by using an impact tester DG-UB type with a constant temperature bath manufactured by Toyo Seiki Seisakusho Co., Ltd.

Further, the material for the denture base of the present embodiment preferably has a flexural modulus of 2700 MPa to 4000 MPa, and more preferably 3000 MPa to 3700 MPa.
Here, the "flexural modulus" refers to the flexural modulus measured by a three-point bending test under the same conditions as the above-mentioned "flexural strength". The method for calculating the flexural modulus is the "secant method".

<Polymer component>
The material for the denture base of the present embodiment contains a polymer component including an acrylic resin.
The weight average molecular weight (Mw) of the polymer component in the present embodiment is preferably 1.2 million or more.
The Mw here means the Mw of the polymer component (whole).
Needless to say, when the polymer component is composed only of the acrylic resin, the Mw of the polymer component and the Mw of the acrylic resin match. Further, when the polymer component is composed of an acrylic resin and rubber, the Mw is the Mw of the entire polymer component (acrylic resin and rubber).
When the Mw of the polymer component is 1.2 million or more, the bending strength of the denture base material is likely to be improved, and the durability (yield point strength) of the denture base is likely to be improved.
Further, the fact that the Mw of the polymer component is 1.2 million or more is also advantageous in terms of machinability when the denture base is manufactured by cutting (for example, in terms of suppressing at least one of cracking and chipping during cutting). be.
As the Mw of the polymer component, 1.3 million or more is more preferable, and 1.4 million or more is further preferable, from the viewpoint of further improving the bending strength. Further, the Mw of the polymer component is usually preferably adjusted to 8 million or less from the viewpoint of productivity.

The polymer component in the present embodiment preferably has a molecular weight distribution (Mw / Mn) of 1.1 to 7.0, more preferably 1.5 to 6.0, and 2.0 to 5 It is more preferably .5.

The weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) in the present specification refer to the values measured by the following GPC measuring method using a gel permeation chromatograph (GPC), respectively.
-GPC measuring device-
LC-10AD manufactured by Shimadzu
-column-
Shodex K-806L 30 cm x 2-Sample preparation-
The polymer component to be measured is dissolved in a solvent (tetrahydrofuran) at room temperature (20 ° C. to 30 ° C.), and a sample solution having a concentration of 0.1% (w / v) is prepared.
-Measurement condition-
100 μL of the sample solution was added to the mobile phase (for example, tetrahydrofuran), the column temperature was 40 ° C., and 1.0 mL / min. Introduce into the column at the flow rate of.
The sample concentration in the sample solution separated by the column is measured with a differential refractometer (RI-101). A universal calibration curve is prepared from the polymethylmethacrylate standard sample, and the weight average molecular weight (Mw), the number average molecular weight (Mn), and the molecular weight distribution (Mw / Mn) of the polymer component are calculated.
For the analysis, for example, data processing software Emper2 (manufactured by Waters) can be used.

Further, the acrylic resin contained in the polymer component is an acrylic resin, an oligomer or a prepolymer obtained by polymerizing a monomer because it is easy to achieve a weight average molecular weight (Mw) of 1.2 million or more of the polymer component. Acrylic resin obtained by polymerizing the above, or an acrylic resin obtained by polymerizing a mixture of an oligomer or a prepolymer and a monomer is preferable. As the oligomer or prepolymer, an oligomer or prepolymer that is fluid at room temperature is particularly suitable.

A normal acrylic resin for dentures is an acrylic resin obtained by polymerizing a mixture of a polymer that is solid at room temperature and a monomer.
However, when an acrylic resin obtained by polymerizing a mixture of a polymer that is solid at room temperature and a monomer is used as the acrylic resin in the present embodiment, the Mw of the polymer component including the acrylic resin is 1.2 million or more. It tends to be difficult to do.
For example, an artificial tooth bed made of an ordinary acrylic resin for artificial teeth is a mixture of an acrylic polymer having a relatively high molecular weight, which is a solid powder at room temperature, a monomer of the acrylic compound, and a polymerization initiator. Then, after polymerizing to a state of fluidity, it is produced by putting it in a plaster mold or the like and curing it by heating or the like. This method for producing a denture base is usually performed by a dental technician, and has an advantage that it is convenient for the dental technician because the polymerization rate is high. However, in this method, since the difference in molecular weight between the powder as a starting material and the monomer is large, it is presumed that the Mw of the acrylic resin is unlikely to increase.
In contrast to the above-mentioned usual method, for example, only the oligomer or prepolymer in a fluid state at room temperature, or the oligomer or prepolymer supplemented with a monomer is added for several days to several days near the polymerization temperature of the oligomer or prepolymer. By polymerizing over a week, the degree of polymerization and the uniformity of polymerization can be improved. As a result, it is considered that the Mw of the acrylic resin can be set to 1.2 million or more, and the Mw of the polymer component can be set to 1.2 million or more.
When the polymer component in the present embodiment contains rubber, the oligomer or prepolymer, or the oligomer or prepolymer to which the monomer is added, and the rubber may be mixed and then polymerized.

(Acrylic resin)
The polymer component includes an acrylic resin.
Since the material for the denture base of the present embodiment contains an acrylic resin having high transparency, it has an advantage that the degree of freedom of coloring is large. Further, since the material for the denture base of the present embodiment contains an acrylic resin, it also has an advantage of being excellent in adhesion to a commercially available acrylic artificial tooth.
The polymer component in the present embodiment may contain only one type of acrylic resin, or may contain two or more types of acrylic resin.

In the present specification, the acrylic resin is composed of a group consisting of a structural unit derived from acrylic acid, a structural unit derived from methacrylic acid, a structural unit derived from an acrylic acid ester, and a structural unit derived from a methacrylic acid ester. Refers to a polymer containing at least one selected.
That is, the acrylic resin in the present specification is at least one selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid ester, and methacrylic acid ester (hereinafter, also referred to as "acrylic monomer"). It is a polymer obtained by polymerizing a monomer component containing it.

The acrylic monomer, which is at least a part of the raw material of the acrylic resin, may be a monofunctional acrylic monomer or a polyfunctional acrylic monomer.
Examples of the monofunctional acrylic monomer include acrylic acid, methacrylic acid, an acrylic acid ester containing one acryloyl group in one molecule, and a methacrylic acid ester containing one methacryloyl group in one molecule.
Examples of the polyfunctional acrylic monomer include an acrylic acid ester containing two or more acryloyl groups in one molecule, a methacrylic acid ester containing two or more methacryloyl groups in one molecule, and the like.

More specifically, as the above acrylic resin,
Acrylic acid homopolymer,
Methacrylic acid homopolymer,
Acrylic acid ester homopolymer,
Methacrylic acid ester homopolymer,
Copolymers of acrylic acid with other monomers (eg, acrylic acid esters, methacrylic acid, methacrylic acid esters, α-olefins (eg ethylene), etc.),
Copolymers of methacrylic acid with other monomers (eg, acrylic acid, acrylic acid esters, methacrylic acid esters, α-olefins (eg ethylene), etc.),
Copolymers of acrylic acid esters with other monomers (eg acrylic acid, methacrylic acid, methacrylic acid esters, α-olefins (eg ethylene), etc.),
Examples include copolymers of methacrylic acid esters with other monomers (eg, acrylic acid, acrylic acid esters, methacrylic acid, α-olefins (eg, ethylene), etc.).

As the acrylic acid ester, an acrylic acid alkyl ester is preferable, a linear alkyl ester of acrylic acid or a branched chain alkyl ester is more preferable, and a linear alkyl ester of acrylic acid is further preferable.
Further, the acrylic acid ester preferably does not contain halogen atoms such as fluorine atoms and chlorine atoms.
As the acrylic acid ester, an acrylic acid alkyl ester having an alkyl group having 1 to 4 carbon atoms contained in the moiety of the alkyl ester is more preferable, methyl acrylate and ethyl acrylate are more preferable, and methyl acrylate is particularly preferable.

As the methacrylic acid ester, a methacrylic acid alkyl ester is preferable, a methacrylic acid linear alkyl ester or a branched chain alkyl ester is more preferable, and a methacrylic acid linear alkyl ester is further preferable.
Further, the methacrylic acid ester preferably does not contain halogen atoms such as fluorine atoms and chlorine atoms.
As the methacrylic acid ester, an alkyl methacrylate ester having 1 to 4 carbon atoms in the alkyl group contained in the moiety of the alkyl ester is more preferable, methyl methacrylate and ethyl methacrylate are more preferable, and methyl methacrylate is particularly preferable.

Further, the acrylic resin is preferably a polymer obtained by polymerizing a monomer component containing a monofunctional acrylic monomer from the viewpoint of reactivity and productivity.
Specifically, the acrylic resin contains 50% by mass or more (preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more) the structural unit derived from the monofunctional acrylic monomer. ) Containing polymer is more preferable.

The monofunctional acrylic monomer is preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid alkyl esters, and methacrylic acid alkyl esters.
From the viewpoint of the material for the denture base and the physical properties (heat resistance) of the denture base, the monofunctional acrylic monomer is more likely to be at least one selected from the group consisting of methacrylic acid and methacrylic acid alkyl ester. preferable.
The preferred ranges of the acrylic acid alkyl ester and the methacrylic acid alkyl ester are as described above.

Preferred forms of the acrylic resin include a form in which the monofunctional acrylic monomer is at least one monomer selected from the group consisting of methacrylic acid and methacrylic acid alkyl esters.
The acrylic resin is preferably derived from a copolymer (that is, a structural unit derived from methacrylic acid and an alkyl methacrylate ester) obtained by polymerizing a monomer component containing methacrylic acid and an alkyl methacrylate ester. It is a copolymer containing a structural unit).
A copolymer of methacrylic acid and an alkyl methacrylate is more preferable, and a copolymer of methacrylic acid and methyl methacrylate (methyl methacrylate) (hereinafter, also referred to as "MMA-MAA copolymer") is more preferable. ).

As a more preferable form of the acrylic resin, the monofunctional acrylic monomer is composed of methacrylic acid and methacrylic acid alkyl ester, and the amount of methacrylic acid with respect to the total amount of methacrylic acid and methacrylic acid alkyl ester is 0.1% by mass. A form of% to 15% by mass (more preferably 1% by mass to 15% by mass, still more preferably 5% by mass to 15% by mass) can also be mentioned.
As the acrylic resin having the preferred form, the monofunctional acrylic monomer is composed of methacrylic acid and methyl methacrylate, and the amount of methacrylic acid with respect to the total amount of methacrylic acid and methyl methacrylate is 0.1% by mass or more. A MMA-MAA copolymer of 15% by mass (more preferably 1% by mass to 15% by mass, even more preferably 5% by mass to 15% by mass) is particularly preferred.
The acrylic resin having the preferred form is advantageous in terms of bending strength of the denture base material and durability of the denture base (yield point strength of the compression test) as compared with, for example, polymethylmethacrylate (PMMA).

The polymer component in the present embodiment may contain only one type of acrylic resin, or may contain two or more types of acrylic resin.
Further, the polymer component in the present embodiment may contain a resin other than the acrylic resin.
However, the content of the acrylic resin in the material for the denture base of the present embodiment (the total content when there are two or more types) may be 60% by mass or more with respect to the total amount of the material for the denture base. It is preferably 80% by mass or more, more preferably 90% by mass or more, preferably 95% by mass or more, and particularly preferably 99% by mass or more.

(Rubber)
The polymer component preferably further contains rubber.
When the polymer component in the present embodiment contains rubber, the impact strength of the material for the denture base is further improved, and the impact resistance (break weight of the falling ball test) when the denture base is used is further improved.
Examples of the type of rubber include acrylic rubber, butadiene rubber, butadiene-acrylic rubber, butadiene-styrene rubber, silicone rubber, and the like.
When the polymer component in the present embodiment contains rubber, the type of rubber may be appropriately selected in consideration of physical properties, but in consideration of the balance of various physical properties such as hardness and impact resistance, butadiene rubber or butadiene -Acrylic rubber is preferable.
When the polymer component in the present embodiment contains rubber, the rubber contained in the polymer component may be only one type or two or more types.

The rubber preferably contains a graft polymer in which a thermoplastic resin component is graft-polymerized on a rubber-like polymer (preferably a rubber-like polymer having a crosslinked structure).

The thermoplastic resin component is not particularly limited as long as it is a monomer component that can be graft-polymerized with a rubber-like polymer, and is, for example, an aromatic vinyl compound, a vinyl cyanide compound, a (meth) acrylic acid ester compound, or (meth). ) Acrylic acid compounds, N-substituted maleimide compounds, α, β-unsaturated carboxylic acid compounds, and anhydrides thereof (for example, maleic anhydride) and the like. These monomer components may be used alone or in combination of two or more.
Here, "(meth) acrylic acid" is a concept that includes both acrylic acid and methacrylic acid (hereinafter, the same applies).

Examples of the rubber-like polymer include an acrylic (co) polymer, a butadiene-based (co) polymer, a silicone-based polymer, and the like, and among them, a butadiene-based (co) polymer is preferable. When the rubber-like polymer is a butadiene-based (co) polymer, the impact strength of the material for the denture base is further improved, and the impact resistance (break weight of the falling ball test) when the denture base is used is further improved.
Here, the "(co) polymer" is a concept that includes both a homopolymer and a copolymer (hereinafter, the same applies).
That is, it is preferable that the rubber contains a graft polymer in which a thermoplastic resin component is graft-polymerized on a butadiene-based (co) polymer.

The acrylic (co) polymer is a copolymer obtained by polymerizing a mixture containing one or more acrylic acid alkyl esters having 2 to 8 carbon atoms and one or more polyfunctional monomers. Polymers are preferred.
The above mixture may be, if necessary, a copolymerizable monomer such as styrene; a styrene derivative such as α-methylstyrene or vinyltoluene; acrylonitrile; methyl methacrylate; etc. (preferably styrene or a styrene and a styrene derivative). May contain a mixture of).
Examples of the acrylic acid alkyl ester in which the alkyl group has 2 to 8 carbon atoms include ethyl acrylate, n-butyl acrylate, and -2-ethylhexyl acrylate, and among these, n-butyl acrylate is more suitable. preferable.
Examples of the polyfunctional monomer include a known acrylic polyfunctional monomer, a known polyvalent aromatic vinyl monomer (for example, divinylbenzene), and the like.

The amount of the components constituting the acrylic (co) polymer is not particularly limited, but the acrylic (co) polymer has an acrylic acid alkyl ester of 50.0% by mass to 99.9% by mass and a polyfunctional single amount. A copolymer obtained by copolymerizing 0.1% by mass to 10% by mass of the body and 0% by mass to 49.9% by mass of a copolymerizable monomer is preferable.
Rubber obtained by graft-polymerizing a thermoplastic resin component on such an acrylic (co) polymer is commercially available, and examples thereof include Mitsubishi Rayon Co., Ltd. "Metabrene (registered trademark) W-450".

Examples of the butadiene-based (co) polymer include a butadiene-n-butyl acrylate copolymer and a butadiene-styrene copolymer.
As the butadiene-based (co) polymer, 1,3-butadiene 5% by mass or more and at least one type of monomer copolymerizable with 1,3-butadiene, 95% by mass or less, are copolymerized. The obtained copolymer is preferable.
Examples of the monomer copolymerizable with 1,3-butadiene include styrene, acrylonitrile, and the above-mentioned acrylic acid alkyl ester having 2 to 8 carbon atoms in the alkyl group.

When copolymerizing 1,3-butadiene and a monomer having copolymerizability with 1,3-butadiene, a polyfunctional monomer may be used in combination.
Here, examples of the polyfunctional monomer include a known acrylic polyfunctional monomer, a known polyvalent aromatic vinyl monomer (for example, divinylbenzene), and the like.

The butadiene-based (co) polymer is a copolymer of butadiene and n-butyl acrylate, from the viewpoint of further improving the impact strength of the material for the artificial tooth bed and further improving the impact resistance of the obtained artificial tooth bed. It is preferably a butadiene-n-butyl acrylate copolymer thus obtained.
Rubber obtained by graft-polymerizing a thermoplastic resin component on such a butadiene-based (co) polymer is commercially available. Trademark) M-521 "and the like.

Examples of the silicone-based polymer include room temperature curable silicone rubber and heat-curable silicone rubber, and specific examples thereof include dimethyl silicone rubber, vinyl methyl silicone rubber, methylphenyl silicone rubber, and fluorosilicone rubber. Be done. As the silicone-based polymer, a known silicone rubber may be used.
Rubber obtained by graft-polymerizing a thermoplastic resin component to a silicone-based polymer is commercially available, and examples thereof include Mitsubishi Rayon Co., Ltd. "Metabrene (registered trademark) S-2001".

The rubber is preferably rubber particles.
When the polymer component in the present embodiment contains rubber particles as rubber, the rubber particles are dispersed in the acrylic resin, so that the impact strength of the denture base material is further improved.
Examples of the rubber particles include rubber particles having a single-layer structure, rubber particles having a multi-layer structure, and the like.
Examples of the rubber particles having a multilayer structure include an inner layer made of a rubber-like polymer such as the above-mentioned acrylic (co) polymer, the above-mentioned butadiene-based (co) polymer, and the above-mentioned silicone-based polymer, and an inner layer. It may be provided with an outer layer made of a resin obtained by polymerizing the above-mentioned thermoplastic resin component.
Further, a rubber-like polymer in which a crosslinkable polyfunctional monomer is copolymerized in a small amount may be used.
As the resin obtained by polymerizing the thermoplastic resin component, a polymer having a glass transition temperature of room temperature or higher is preferable.

For example, the acrylic rubber particles are a single-layer structure made of a rubber-like polymer containing methyl methacrylate as a main component, and an elastic resin layer containing an acrylic acid alkyl ester such as n-butyl acrylate as a main component. It may have a multi-layer structure in which a thermoplastic resin layer containing methyl methacrylate as a main component is provided around the inner layer, or known acrylic rubber particles may be used.

Further, the rubber particles are more preferably rubber particles which are graft polymers in which a thermoplastic resin component is graft-polymerized on a rubber-like polymer (preferably a rubber-like polymer having a crosslinked structure).
Further, as described above, examples of the rubber-like polymer include an acrylic (co) polymer, a butadiene-based (co) polymer, a silicone-based polymer, and the like, and among them, the butadiene-based (co) polymer is preferable. ..

The average particle size of the rubber particles is preferably in the range of 0.03 μm to 2.0 μm. Thereby, the dispersed state of the rubber particles can be suitably maintained in the material for the denture base. Rubber particles having such a particle size can be produced by an emulsion polymerization method.

When the polymer component in the present embodiment contains rubber, the rubber content is preferably 1% by mass or more and 10% by mass or less with respect to the total amount of the denture base material.
When the rubber content is 1% by mass or more, the impact strength of the material for the denture base is further improved, and the impact resistance (breaking weight of the falling ball test) when the denture base is used is further improved.
When the rubber content is 10% by mass or less, the bending strength of the material for the denture base is further improved, and the durability (yield point strength of the compression test) when the denture base is used is further improved. Further, when the rubber content is 10% by mass or less, the flexural modulus of the material for the denture base is further improved, so that it is less likely to be deformed, and the workability when producing the denture base is further improved.
The upper limit of the rubber content is more preferably 8% by mass, further preferably 7% by mass.
The lower limit of the rubber content is preferably 1.5% by mass, more preferably 2% by mass.

That is, the material for the artificial tooth bed of the present embodiment contains a copolymer of methacrylic acid alkyl ester and methacrylic acid (preferably an MMA-MAA copolymer) and rubber as a polymer component to provide bending strength. It is easy to achieve a maximum stress intensity factor of 1.9 MPa · m ^1/2 or more and a total fracture work of 900 J / m ² or more at 110 MPa or more.

<Other ingredients, etc.>
The denture base material of the present embodiment may contain other components, if necessary.
Examples of other components include colorants.
The colorant is not particularly limited, and pigments, dyes, colored fibers and the like can be used, but pigments and dyes are preferable, and pigments are particularly preferable.
When the artificial tooth bed material of the present embodiment contains a colorant, the content of the colorant is preferably 0.001 part by mass to 0.20 part by mass, preferably 0.001 part by mass, based on 100 parts by mass of the polymer component. Parts to 0.15 parts by mass are preferable, and 0.001 parts to 0.10 parts by mass are more preferable.
When the content of the colorant is 0.20 parts by mass or less, it is easier to achieve a bending strength of 110 MPa or more for the denture base material.

Further, the material for the denture base of the present embodiment may contain a material imitating a blood vessel, but the content of the material having a minor axis of 20 μm or more is 0. It is preferably less than 001 parts by mass, more preferably less than 0.0005 parts by mass. By adjusting the content of the material having a minor axis of 20 μm or more within the above range, it becomes easy to adjust the bending strength to 110 MPa or more.
When the material is fibrous, the minor axis is the average diameter of the fibers.

In the denture base of the present embodiment, the uncolored denture base material as the denture base material of the present embodiment is cut to obtain an uncolored denture base, and then a coloring agent is applied to the uncolored denture base. It may be obtained by applying coloring by using. In this case, the denture base material of the present embodiment does not necessarily have to contain a colorant.

In the denture base material of the present embodiment, the content of the polymer component is preferably 90% by mass or more with respect to the total amount of the denture base material. When the rubber particles are contained, it is preferably 90% by mass or more and 99% by mass or less, more preferably 92% by mass or more and 98.5% by mass or less, and 92% by mass or more and 98% by mass or less. Is particularly preferred.
When the content of the polymer component is 90% by mass or more, it is easy to achieve a bending strength of 110 MPa or more for the denture base material.

Further, the size of the material for the denture base of the present embodiment is not particularly limited as long as the size of the material for the denture base can be obtained by cutting.
Further, the shape of the denture base material of the present embodiment is not particularly limited, but from the viewpoint of ease of cutting, a rectangular parallelepiped shape that is easy to fix to a cutting machine and easy to create a cutting program is preferable. A large rectangular parallelepiped shape that can cut a plurality of pieces at once is more preferable.
For example, in the case of a block having a rectangular parallelepiped shape of 230 mm × 190 mm × 30 mm, it is efficient to obtain four all-bed denture beds at one time. Further, from the viewpoint of effective use of the material, if the thickness of the rectangular parallelepiped is too thick, the portion to be discarded increases, so that the thickness of the material for the denture base is preferably 20 mm to 40 mm.
Further, from the viewpoint of cutting a plurality of denture base materials at once, it is preferable to install a changer device capable of automatically exchanging the denture base materials in the cutting machine.

The method for producing the artificial tooth bed material of the present embodiment is not particularly limited, but an oligomer or a prepolymer or a mixture of an oligomer or a prepolymer and a monomer is used as a raw material and is used as a raw material in the vicinity of the polymerization temperature for several days to one week. A method of slowly polymerizing over a certain period of time is preferable. According to such a manufacturing method, it is easy to manufacture a denture base material containing a polymer component having a Mw of 1.2 million or more. That is, it is easy to obtain a material for a denture base having a bending strength of 110 MPa or more.
Further, when the artificial tooth bed material of the present embodiment contains the rubber particles, the rubber particles are mixed with an oligomer or a prepolymer or an oligomer or a prepolymer to which a monomer is added, and then, in the vicinity of the polymerization temperature, It is preferable to slowly polymerize over a period of several days to one week to produce a material for artificial dentition.
The raw material may contain other components (colorant, initiator, chain transfer agent, etc.), if necessary.
As the chain transfer agent, known compounds can be used without any limitation, and for example, n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, 1,4-butanedithiol, 1,6-hexanedithiol and the like can be used. Alkyl mercaptans; aromatic mercaptans; thioglycolic acid esters such as butanediol bisthioglycolate and hexanediol bisthioglycolate, ethylene glycol bisthiopropionate, butanediol bisthiopropionate, trimethyl propanthris Mercaptopropionic acid esters such as thiopropionate and pentaerythritol tetrakisthiopropionate: terpinolene; α-styrene dimer and the like can be mentioned. The chain transfer agent may be only one kind or two or more kinds.

[Denture base, denture with floor]
The denture base of the present embodiment includes the material for the denture base of the above embodiment.
Therefore, the denture base of the present embodiment is excellent in durability (yield point strength).
The denture base of the present embodiment may be a denture base for all dentures (so-called full dentures) or a denture base for partial dentures (so-called partial dentures).
Further, the denture base of the present embodiment may be a denture base for maxillary dentures (hereinafter, also referred to as "maxillary denture base"), or a denture base for lower jaw dentures (hereinafter, "lower denture base"). It may also be a set of a denture base for the maxilla and a denture base for the lower jaw.

Further, the denture base of the present embodiment may be partially composed of the denture base material of the present embodiment, or may be entirely composed of the denture base material of the present embodiment.
As an example of a denture base in which only a part thereof is made of the material for the denture base of the present embodiment, at least a part of the resin portion of the denture base (so-called metal floor) including the metal part and the resin part is the present implementation. A denture base made of a denture base material of the present embodiment; a denture base made of only a part of a denture base made of only a resin portion (so-called resin bed); and the like are made of the denture base material of the present embodiment. Can be mentioned.
An example of a denture base made entirely of the material for the denture base of the present embodiment is a denture base made of only a resin portion.

The denture base of the present embodiment may be a denture base obtained by cutting a denture base material which is a block body having a thickness of 10 mm or more and 40 mm or less, which is a preferable form of the denture base material of the present embodiment. Especially preferable.

The denture with a floor of the present embodiment includes the denture base of the above embodiment and artificial teeth fixed to the denture base.
Therefore, the denture with a floor of the present embodiment is excellent in the durability (yield point strength) of the denture base.
The denture with a floor of the present embodiment may be a partial denture or a full denture. That is, the denture with a floor of the present embodiment may be provided with at least one artificial tooth.
Further, the denture with a floor of the present embodiment may be a maxillary denture, a mandibular denture, or a set of a maxillary denture and a mandibular denture.

Examples of the material of the artificial tooth include acrylic resin. Examples of acrylic resins are as described above. Further, the artificial tooth may contain a filler or the like in addition to the acrylic resin.

FIG. 1 is a perspective view conceptually showing an example of a denture with a floor according to the present embodiment.
As shown in FIG. 1, the maxillary denture 10 which is an example of the denture with a floor of the present embodiment is fixed to the maxillary denture 20 and the maxillary denture 20 which is an example of the denture of the present embodiment. It is provided with an artificial tooth 12. In FIG. 1, only one of the plurality of artificial teeth is designated by reference numeral 12.
The maxillary denture base 20 is manufactured by cutting the material for the denture base of the present embodiment. The maxillary denture 10 is produced by fixing the artificial tooth 12 to the maxillary denture base 20.

Although not shown, the denture base may be divided into a plurality of parts, and only a part thereof may be produced by cutting the material for the denture base of the present embodiment.
Further, the denture base and the denture with a floor of the present embodiment are not limited to the denture base for the maxilla and the denture for the maxilla, and are the denture base for the lower jaw and the denture for the lower jaw. Of course, it is also good.

[Manufacturing method of denture base, manufacturing method of denture with floor]
The method for manufacturing a denture base according to the present embodiment includes a cutting step of cutting the material for the denture base according to the above embodiment to obtain a denture base.
Cutting in the cutting process can be performed according to, for example, a cutting program created by a CAD (Computer Aided Design) / CAM (Computer Aided Manufacturing) system. Further, cutting can be performed using a CNC (Computer Numerical Control) cutting machine.
The cutting program can be created by a known method based on the three-dimensional shape of the patient's oral cavity. If a denture base suitable for the patient has already been prepared, three-dimensional (3D) data is obtained by optically scanning this denture base, and a cutting program is created based on the obtained 3D data. You may.

The method for manufacturing the denture base of the present embodiment may include other steps other than the cutting step, if necessary. Examples of other steps include a coloring step of coloring the denture base.

Further, the method for manufacturing a denture with a floor of the present embodiment includes a cutting step of obtaining a denture base by cutting the material for the denture base of the above embodiment, and a fixing step of fixing an artificial tooth to the denture base. ..
The preferred form of cutting in the cutting process is as described above.
The artificial tooth can be fixed in the fixing step by a usual method using an adhesive. As the adhesive, for example, a dental adhesive resin cement "Super Bond" (registered trademark) manufactured by Sun Medical Co., Ltd. can be used.
Further, prior to fixing the artificial tooth to the denture base using an adhesive, a known surface treatment (easy adhesion treatment) may be applied to at least one surface (adhesive surface) of the denture base and the artificial tooth in advance. good.

The method for manufacturing a denture with a floor of the present embodiment may include other steps other than the cutting step and the fixing step, if necessary. Other steps include a coloring step of coloring the denture base of a denture with a floor.

Hereinafter, embodiments of the present invention will be described in more detail by way of examples, but the present embodiment is not limited to the following examples as long as the gist of the present invention is not exceeded.

[Example 1]
<Manufacturing of materials for denture base>
Liquid A [5 parts by mass of methacrylic acid monomer, 2 parts by mass of MUX-60 (manufactured by UMG BS Co., Ltd .; rubber), 0 with respect to 93 parts by mass of prepolymerized methyl methacrylate syrup that is fluid at room temperature. .03 parts by mass of terpinolene (manufactured by Tokyo Kasei Kogyo Co., Ltd .; chain transfer agent) and 0.002 parts by mass of AIBN (2,2'-Azobis (isobutyronitrile); polymerization initiator) are added and mixed at room temperature to be uniform. Solution] 7.032 parts by mass was added, mixed at room temperature to homogenize, and then defoamed. The defoamed composition was poured into a mold having a gasket interposed between two pieces of inorganic glass, polymerized at 40 ° C. for 48 hours and 120 ° C. for 5 hours, and a rectangular parallelepiped resin block having a thickness of 30 mm ( Material for denture base) was prepared.
Here, MUX-60 (manufactured by UMG ABS Co., Ltd.) is a rubber obtained by graft-polymerizing a thermoplastic resin component to a butadiene-based (co) polymer which is a rubber-like polymer having a crosslinked structure. ..
The material of the obtained resin block is a mixture of a methyl methacrylate-methacrylic acid copolymer (MMA-MAA copolymer) and rubber (MUX-60).

<Preparation of test piece for bending test>
By cutting the resin block which is the material for the denture base obtained as described above, a rectangular parallelepiped bending test test piece having a size of 80 mm × 10 mm × 4 mm was obtained.

<3-point bending test (measurement of bending strength and flexural modulus)>
The bending test piece was subjected to a three-point bending test in accordance with JIS K7171 (2008) using a 5-piece bending tester 2001-5 manufactured by Intesco, and the bending strength and flexural modulus were measured. did.
Here, the test speed was set to 2 mm / min, and the distance between the fulcrums was set to 64 mm. The bending elastic modulus was calculated by the secant method.
The results are shown in Table 1 below.

<Preparation of test piece for Charpy impact test>
A resin piece having the same size as the bending test test piece was produced by the same method, and a notch having a shape A specified in JIS K7111-1 (2012) was formed on the resin piece with a remaining width of 8.0 mm. A test piece for impact test (test piece with a single notch) was obtained.

<Charpy impact test (measurement of impact strength)>
The above impact test piece was subjected to a Charpy impact test under the conditions of edgewise impact using the impact tester DG-UB type with a constant temperature bath manufactured by Toyo Seiki Seisakusho, in accordance with JIS K7111-1 (2012). The impact strength was measured.
Furthermore, in this test, after the pendulum collided with the test piece, the angle (°) at which the pendulum shook was measured. This angle indicates that the smaller the number, the larger the energy absorption at the time of collision, that is, the better the impact resistance.
The above results are shown in Table 1 below.

<Preparation of test piece for fracture toughness test>
By cutting the resin block which is the material for the artificial tooth bed obtained above, a resin piece having a length of 39 mm, a height of 8 mm and a width of 4 mm is produced, and the resin piece is specified in JIS T6501 (2012). A notch was provided to obtain a test piece for fracture toughness test (test piece with notch).

<Fracture toughness test (measurement of maximum stress intensity factor and total fracture work)>
The fracture toughness test piece was subjected to a fracture toughness test by bending test in accordance with JIS T6501 (2012) using a universal testing machine (model number: 210X type) manufactured by Intesco, and the maximum stress intensity factor and total fracture were achieved. Measured work. The test speed was 1 mm / min, and the distance between the fulcrums was 32 mm.
The results are shown in Table 1 below.

<Weight average molecular weight (Mw), number average molecular weight (Mn), molecular weight distribution (Mw / Mn) of polymer>
With respect to the polymer component in the resin block, the weight average molecular weight (Mw), the number average molecular weight (Mn), and the molecular weight distribution (Mw / Mn) were measured according to the above-mentioned GPC measuring method.
The results are shown in Table 1 below.

<Preparation of denture base for compression test>
The 3D data of the maxillary denture base prepared in Comparative Example 1 described later was acquired using a 3D scanner.
From this 3D data, a cutting program was created to obtain the denture base for the upper jaw by cutting the resin block as a material for the denture base using CAD / CAM software.
According to this cutting program, the resin block was cut using a CNC cutting machine to obtain a maxillary denture base.

<Compression test of denture base (measurement of yield point strength)>
A compression test (measurement of yield point strength) of the maxillary denture base was performed using a universal material tester AG-100kNX with a constant temperature bath manufactured by Shimadzu Corporation.
Specifically, the maxillary denture base is placed on a test table so that the mucosal surface (the surface in contact with the ridge and the palate) is on the upper side, and then the central portion of the maxillary denture base is placed in a circle having a diameter of 20 mm. It was compressed at a rate of 1 mm / min by the bottom surface of a columnar rod (material: carbon steel S45C).
In the above compression, the displacement and the strength were recorded, and the maximum point of the strength was defined as the yield point strength.
The results are shown in Table 1 below.

<Preparation of denture base for ball drop test>
Using CAD software, thinned 3D data was created by reducing the thickness of the maxillary palate portion of the 3D data of the maxillary denture base obtained during the preparation of the above-mentioned compression test denture base by 1.2 mm.
From this thinned 3D data, a cutting program for obtaining a thinned denture base by cutting the above resin block as a material for a denture base was created using CAD / CAM software.
According to this cutting program, the resin block was cut using a CNC cutting machine to obtain a thinned maxillary denture base.

<Denture bed drop test (measurement of fracture weight)>
The ball drop test (measurement of fracture weight) of the above-mentioned thinned maxillary denture base was performed.
Specifically, the thinned maxillary denture base is placed on a test table with the mucosal surface (the surface in contact with the ridge and palate) facing up, and then collides with the central part of the thinned maxillary denture base. The steel balls were dropped from a height of 100 cm in order from the lightest one, and the weight when the denture base was cracked was recorded, and this was taken as the breaking weight.
The weight of the dropped steel balls is 6.9 g, 8.4 g, 9.0 g, 10.0 g, 11.2 g, 11.9 g, 13.8 g, 14.0 g, 16.3 g, 16 in order from the lightest one. They were 0.7 g, 18.9 g, 20.0 g, 21.7 g, 23.8 g, 24.8 g, 28.0 g, 28.2 g, 33.2 g and 45.5 g.
The results are shown in Table 1 below.

<Evaluation of machinability of denture base material>
In the process of cutting the above resin block as a material for a denture base to obtain a denture base, the machinability was evaluated based on the following evaluation criteria.
The results are shown in Table 1 below.

-Evaluation criteria for machinability-
A: No cracks or chips were generated during cutting, and the machinability was good.
B: At least one of cracking and chipping occurred during cutting, and the machinability was poor.

[Example 2]
In Example 1, the same operation as in Example 1 was performed except that the amount of methyl methacrylate syrup was changed to 88 parts by mass and the amount of methacrylic acid monomer was changed to 10 parts by mass. A resin block (material for prosthesis bed) was prepared.
The material of the obtained resin block is a mixture of a methyl methacrylate-methacrylic acid copolymer (MMA-MAA copolymer) and rubber (MUX-60).

[Example 3]
In Example 1, the same operation as in Example 1 was performed except that 2 parts by mass of MUX-60 was changed to 2 parts by mass of Kaneace (registered trademark) M-521 (manufactured by Kaneka Corporation; rubber). A rectangular parallelepiped resin block (material for denture base) having a thickness of 30 mm was produced.
Here, "M-521" is a rubber obtained by graft-polymerizing a thermoplastic resin component to a butadiene-based (co) polymer which is a rubber-like polymer having a crosslinked structure.
The material of the obtained resin block is a mixture of a methyl methacrylate-methacrylic acid copolymer (MMA-MAA copolymer) and rubber (M-521).

[Comparative Example 1]
In Example 1, a bending test test piece, an impact test piece test piece, a fracture toughness test test piece, and a compression test denture base (upper jaw denture base) are used for bending test as follows. The same operation as in Example 1 was performed except that the test piece, the test piece for the impact test piece, the test piece for the fracture toughness test, and the denture base for the upper jaw were changed.
The results are shown in Table 2.

<Preparation of test piece for bending test>
(Preparation of plaster mold for test piece for bending test)
First, a flask for making a denture (a set of a lower flask mold and an upper flask mold) was prepared.
Next, a rectangular parallelepiped plate having a length, width, and thickness slightly larger than the size of 80 mm (length) × 10 mm (width) × 4 mm (thickness) was carved from the resin block. NEW ACROSEP (manufactured by GC Corporation), a resin separating agent for denture bases, was applied to the entire machined plate.
Next, a gypsum dental blaster (manufactured by Noritake Co., Ltd.) mixed with a predetermined amount of water was poured into the lower flask mold to the full and left for a while. When the gypsum had hardened, the central part of the gypsum was pushed to form a dent large enough to accommodate the above plate.
After the gypsum had completely hardened, the dental hard gypsum New Diamond Stone Natural Gray (manufactured by Morita Co., Ltd.) mixed with a predetermined amount of water was poured into the above depression and left for a while. When the hard gypsum had hardened, the board coated with the above-mentioned separating agent was buried in the hard gypsum so that only the upper surface of the board was exposed, and the surface of the hard gypsum was smoothed.
After the hard gypsum had completely hardened, the above-mentioned separating agent was applied to the entire surface of the gypsum containing the hard gypsum.
Next, after mounting the upper flask mold on the lower flask mold, hard gypsum new diamond stone natural gray mixed with a predetermined amount of water was piled up so that the above plate was hidden.
The plaster dental blaster mixed with a certain amount of water was then poured from the dental flask to the extent that it overflowed, and then the lid was closed. After the gypsum had hardened, the lower flask mold and the upper flask mold were separated, and the plate was removed.
As described above, a gypsum mold (a set of a gypsum mold upper mold and a gypsum mold lower mold) for a test piece for a bending test was obtained in a flask for making a denture.
Here, the gypsum mold upper mold was made in the flask upper mold, and the gypsum mold lower mold was made in the flask lower mold. In the gypsum mold upper mold and the gypsum mold lower mold, when the two are combined, a space having the shape of the above plate is formed.
Then, the above-mentioned separating agent was applied to the entire gypsum surface of the gypsum mold upper mold and the gypsum mold lower mold.

(Preparation of test piece for bending test)
A plate made of PMMA-based resin is obtained using a flask for producing a denture on which a plaster mold of the test piece for bending test is produced, and the obtained plate is polished to perform a bending test test having a size of 80 mm × 10 mm × 4 mm. Pieces were made. The detailed operation is shown below.
First, the floor resin material Akron Clear No. 5 (manufactured by GC Corporation) was prepared, and 6 g of the powder material and 2.5 g of the liquid material were weighed in a container and mixed. When the obtained mixture was left to stand for a while to form a rice cake, the rice cake-like mixture was placed in a large amount on the dent of the plaster mold lower mold prepared in the flask lower mold to shape it.
Next, the flask upper mold in which the gypsum mold upper mold was produced was placed on the flask lower mold, and pressure was applied by a press machine. Next, the flask upper mold was removed, the resin material for the rice cake-like floor protruding from the depression was removed, the flask upper mold was placed again, and pressure was applied with a press machine. Then, the flask (a flask in which the upper flask mold and the lower flask mold were combined) was fixed with a flask clamp.
This flask was placed in a pan containing water and slowly heated to 100 ° C. for 30 minutes or more in a gas microwave oven. After reaching 100 ° C., the mixture was heated for 30 to 40 minutes, then the heating was terminated and the mixture was cooled to 30 ° C.
Next, the lower flask mold and the upper flask mold were separated, then the gypsum mold was broken, and the finished plate (PMMA-based resin) was taken out. The removed plate was polished to obtain a rectangular parallelepiped plate having a size of 80 mm × 10 mm × 4 mm, which was used as a test piece for bending test (material is PMMA resin).

<Preparation of test pieces for impact test>
A resin piece having the same size as the bending test test piece obtained above was produced by the same method, and a notch having a shape A was provided on the resin piece in the same manner as the impact test piece test piece of Example 1, and the impact was achieved. It was used as a test piece for a test piece.

<Preparation of test piece for fracture toughness test>
By cutting the resin block which is the material for the artificial tooth base obtained above, a resin piece having a length of 39 mm, a height of 8 mm and a width of 4 mm was produced, and the test piece for the fracture toughness test of Example 1 was produced on this resin piece. A notch was provided in the same manner as in the above, and a test piece for fracture toughness test (test piece with a notch) was used.

<Preparation of denture base for compression test>
(Making wax dentures)
The outline impressions of the upper and lower jaws of the patient were taken, a tray having a shape suitable for the patient was prepared from the outline impression, and the precise impression of the patient was obtained using the obtained tray. Based on the precision impressions obtained, a separate upper and lower gypsum model was created to suit the patient.
Next, the upper and lower parts of the gypsum model were connected, and an occlusal bed made of a base plate and wax was prepared to reproduce the upper and lower occlusions.
Next, the patient's oral cavity is observed to observe the state of jaw movement, the jaw movement is reproduced on the occlusal bed, the occlusal state is obtained three-dimensionally, the occlusal position is determined, and the denture bed made of wax is used. (A set of maxillary denture base and mandibular denture base) was prepared.
The obtained wax denture base is lined with artificial teeth to which the wax pattern separating agent SEP (manufactured by Matsufu Co., Ltd.) has been applied in advance, and then trial fitting and adjustment are performed to obtain a wax denture (with a maxillary denture). A set with a mandibular denture) was prepared.

(Making a plaster mold for a denture base)
First, a flask for making a denture composed of a lower flask mold and an upper flask mold was prepared.
Further, the artificial tooth was removed from the wax denture, and a wax denture base was prepared.
Next, the wax denture base and the above-mentioned plaster model were put into a flask lower mold, and a plaster dental blaster mixed with a predetermined amount of water was poured into the flask and left for a while. After the gypsum had hardened, the above-mentioned separating agent was dropped on the gypsum and applied to the whole using a brush. Then, the flask upper mold was placed on the flask lower mold, the plaster was poured into the frame to the full frame, the lid was put on, and the plaster was left until it was completely hardened.
After the gypsum had hardened, the upper flask mold and the lower flask mold were separated, warmed with hot water to dissolve the wax, and the base plate was removed.
From the above, a gypsum mold for a denture base was obtained, which consisted of a gypsum mold upper mold and a gypsum mold lower mold.
Here, the gypsum mold upper mold was made in the flask upper mold, and the gypsum mold lower mold was made in the flask lower mold. In the gypsum mold upper mold and the gypsum mold lower mold, when the two are combined, a space in the shape of the wax denture base is formed.
Then, the above-mentioned separating agent was applied to the entire gypsum surface of the gypsum mold upper mold and the gypsum mold lower mold.

(Preparation of denture base for compression test)
In the preparation of the test piece for bending test of Comparative Example 1, the denture base is the same as the preparation of the test piece for bending test except that the gypsum mold of the test piece for bending test is changed to the gypsum mold for the denture base. (A set of a denture base for the upper jaw and a denture base for the lower jaw; the material is PMMA-based resin) was obtained.
Of these, the maxillary denture base was used for the compression test (measurement of yield point strength).

[Comparative Example 2]
In Comparative Example 1, Akron Clear No. 5 (manufactured by GC Corporation), Akron Live Pink No. The same operation as in Comparative Example 1 was performed except that it was changed to 8 (manufactured by GC Corporation). The material for the denture base and the material of the denture base are PMMA-based resins.
The results are shown in Table 1 below.

[Comparative Example 3]
In Comparative Example 1, Akron Clear No. 5 (manufactured by GC Corporation), Paraexpress Ultra Pink Live No. The same operation as in Comparative Example 1 was performed except that it was changed to 34 (manufactured by Heraeus Kurzer). The material for the denture base and the material of the denture base are PMMA-based resins.
The results are shown in Table 1 below.

[Comparative Example 4]
In Comparative Example 1, Akron Clear No. 5 (manufactured by GC Corporation) is L'accent Live Pink No. Changed to 8 (manufactured by GC Corporation), and its Laxon Live Pink No. The same operation as in Comparative Example 1 was carried out except that the ratio of the powder material and the liquid material (powder material / liquid material) of No. 8 was mixed at 100/50 (g / ml) to obtain a mixture. In addition, L'accent Live Pink No. Reference numeral 8 is a PMMA-based denture base resin that satisfies the additional required characteristics (maximum stress intensity factor and total fracture work) for impact-resistant materials defined by JIS T6501. That is, the material for the denture base and the material of the denture base are PMMA-based resins. The results are shown in Table 1 below.
Further, in Comparative Example 4, a material for a denture base and a denture base for a ball drop test (thinned maxillary denture base) were prepared as follows, and a ball drop test was performed.

<Manufacturing of materials for denture base>
After preparing the denture base for the falling ball test in Example 1, a resin block having a hole slightly larger than the denture base for the falling ball test was prepared in the center, and the resin block was placed on a smooth iron plate slightly larger than the resin block. I put it.
Next, L'accent Live Pink No. The powder material and the liquid material of No. 8 were weighed in a container, and the ratio of the powder material to the liquid material (powder material / liquid material) was mixed at 100/50 (g / ml). When the obtained mixture was left to stand for a while to form a rice cake, the rice cake-like mixture was placed in the hole portion of the resin block placed on the above iron plate so as to fill the hole portion, and then the block was charged. An iron plate of the same size as the above iron plate was placed on top, and pressure was applied with a press machine. After that, it was fixed with a clamp.
The resin block fixed by this clamp was placed in a pan containing water and slowly heated to 100 ° C. for 30 minutes or more in a gas microwave oven. After reaching 100 ° C., the mixture was heated for 30 to 40 minutes, then the heating was terminated and the mixture was cooled to 30 ° C.
Next, remove the clamp and the upper and lower iron plates, and in the center hole part, L'accent Live Pink No. A rectangular parallelepiped resin block (material for a denture base) having a thickness of 30 mm containing the cured product of No. 8 was prepared.

<Preparation of denture base for ball drop test>
According to the cutting program created from the thinning 3D data created in Example 1, the resin block was cut using a CNC cutting machine to obtain a thinning maxillary denture base.

<Denture bed drop test (measurement of fracture weight)>
The ball drop test (measurement of fracture weight) of the thinned maxillary denture base was performed by the same method as in Example 1.
The results are shown in Table 1 below.

[Comparative Example 5]
In Comparative Example 1, Akron Clear No. 5 (manufactured by GC Corporation) Pro Impact Live Pink No. Changed to 8 (manufactured by GC Corporation), and its Pro Impact Live Pink No. The same operation as in Comparative Example 1 was carried out except that the ratio of the powder material and the liquid material (powder material / liquid material) of No. 8 was mixed at 100/50 (g / ml) to obtain a mixture. In addition, Pro Impact Live Pink No. Reference numeral 8 is a PMMA-based denture base resin that satisfies the additional required characteristics (maximum stress intensity factor and total fracture work) for impact-resistant materials defined by JIS T6501. That is, the material for the denture base and the material of the denture base are PMMA-based resins.
The results are shown in Table 1 below.

-Explanation of Table 1-
-The "angle" of the Charpy impact test refers to the angle (°) at which the pendulum swings after the pendulum collides with the test piece.
-"Watt%" indicates the mass% with respect to the total amount of the resin block (material for the denture base).

As shown in Table 1, the implementation satisfying that the bending strength is 110 MPa or more, the maximum stress intensity factor is 1.9 MPa · m ^1/2 or more, and the total fracture work is 900 J / m ² or more. The materials for the prosthesis bed of Examples 1 to 3 were excellent in hardness (flexural modulus). Further, the denture bases of Examples 1 to 3 produced using this denture base material were excellent in durability (yield point strength). Further, since the materials for the denture base of Examples 1 to 3 have high impact strength, they are also excellent in impact resistance. In addition, these materials for denture bases were also excellent in machinability.
On the other hand, the materials for artificial dentition of Comparative Examples 1 to 3 having a bending strength of less than 110 MPa, a maximum stress intensity factor of less than 1.9 MPa · m ^1/2 , or a total fracture work of less than 900 J / m ² . It can be seen that the hardness (flexural modulus) is low and the impact resistance (impact strength) is low. Further, it can be seen that the denture base materials of Comparative Examples 4 and 5 having a bending strength of less than 110 MPa have a low hardness (flexural modulus). Further, it can be seen that the denture bases of Comparative Examples 1 to 5 produced by using these denture base materials have low durability (yield point strength).

[Reference Example 1]
As Reference Example 1, an example of a method for estimating the fracture toughness of the denture base material used as the raw material of the denture base based on the denture base is shown.
It is practically difficult to cut out a test piece having a length of 39 mm, a height of 8 mm, and a width of 4 mm from the denture base.
However, the fracture toughness of the denture base material used as the raw material of the denture base can be estimated by performing the following micro-fracture toughness test on the denture base.

-Micro-fracture toughness test-
A micro test piece having a length of 18.5 mm, a height of 4 mm, and a width of 2 mm was cut out from the denture base, and the depth of the cut was 1.5 mm and the depth of the notch was 50 to 200 μm for the obtained micro test piece. The fracture toughness test was carried out under the same conditions as the fracture toughness test of the denture base material, except that the denture base material was not immersed in water and the distance between fulcrums was set to 16 mm. This fracture toughness test is referred to as "micro fracture toughness test", and the obtained maximum stress intensity factor and total fracture work are referred to as "micro maximum stress intensity factor" and "micro total fracture work", respectively.

For each of the denture bases of Examples 1, 2 and 3, the minute maximum stress intensity factor and the minute total fracture work were measured.
The obtained results are shown in Table 2 below.
Table 2 below also shows the maximum stress intensity factor and total fracture work of the denture base material of each example.

FIG. 2 is a graph showing the relationship between the minute maximum stress intensity factor of the denture base and the maximum stress intensity factor of the denture base material, which was created based on the results in Table 2.
FIG. 3 is a graph showing the relationship between the micrototal destruction work of the denture base and the total destruction work of the material for the denture base, which was created based on the results in Table 2.
As shown in FIGS. 2 and 3, it was found that the maximum stress intensity factor and the total fracture work of the denture base material are directly proportional to the minute maximum stress intensity factor and the total fracture work of the denture base, respectively. Therefore, it was found that the maximum stress intensity factor and total fracture work of the denture base material used as the raw material of the denture base can be estimated by measuring the minute maximum stress intensity factor and the minute total fracture work of the denture base.
From the viewpoint of improving durability (yield point strength of compression test), for example, the micro maximum stress intensity factor of the denture base is preferably 1.6 MPa · m ^1/2 or more, and the micro total fracture work is 340 MPa · m. It is preferably ^1/2 or more.

[Reference Example 2]
As Reference Example 2, an example of a method of estimating the bending strength of the denture base material used as the raw material of the denture base based on the denture base is shown.
It is practically difficult to cut out a test piece having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm from the denture base.
However, by performing the following micro-bending test on the denture base, the bending strength of the denture base material used as the raw material of the denture base can be estimated.

-Micro bending test-
A micro test piece with a length of 25 mm, a width of 2 mm, and a thickness of 2 mm is cut out from the denture base, and a three-point bending test is performed on the obtained micro test piece under the conditions of a test speed of 1 mm / min and a distance between fulcrums of 20 mm. .. This three-point bending test is referred to as a "micro bending test", and the obtained bending strength is referred to as a "micro bending strength".
Among the measurement conditions of the "fine bending test", the conditions other than the above conditions are the same as the conditions of the three-point bending test of the denture base material.
A "micro-bending test" is measured for a plurality of denture beds (for example, 10 samples), and a graph showing the relationship between the micro-bending strength of the denture base and the impact strength of the material for the denture base is created. From this graph, the bending strength of the denture base material used as the raw material of the denture base can be estimated by measuring the minute bending strength of the denture base.

10 Maxillary dentures (bed dentures)
12 Artificial teeth 20 Maxillary denture base (denture base)

Claims (11)

Contains polymer components including acrylic resin and rubber ,
The acrylic resin is a copolymer of methacrylic acid and methyl methacrylate.
The rubber contains a graft polymer obtained by graft-polymerizing a butadiene-based (co) polymer with a thermoplastic resin component.
Flexural strength measured by a three-point bending test with a test speed of 2 mm / min and a distance between fulcrums of 64 mm, in accordance with JIS K7171 (2008), when a test piece with a length of 80 mm, a width of 10 mm, and a thickness of 4 mm is used. Is 110 MPa or more,
Maximum stress intensity measured by fracture toughness test by bending test under JIS T6501 (2012) with test speed of 1 mm / min when a notched test piece with a length of 39 mm, a height of 8 mm and a width of 4 mm is used. A material for artificial dentition with a coefficient of 1.9 MPa · m ^1/2 or more and a total destruction work of 900 J / m ² or more. The material for a denture base according to claim 1, wherein the bending strength is 200 MPa or less. The denture base material according to claim 1 or 2, wherein the maximum stress intensity factor is 3.5 MPa · m ^1/2 or less, and the total fracture work is 2500 J / m ² or less. When a test piece with a single notch having a length of 80 mm, a width of 10 mm, a remaining width of 8 mm, and a thickness of 4 mm is provided with a notch of shape A specified in JIS K7111-1 (2012), JIS K7111-1 ( The artificial tooth bed according to any one of claims 1 to 3, wherein the impact strength measured by the Charpy impact test under the condition of edgewise impact according to 2012) is 1.6 kJ / m ² or more. Material for. The material for a denture base according to any one of claims 1 to 4, wherein the polymer component has a weight average molecular weight of 1.2 million or more. The material for a denture base according to any one of claims 1 to 5 , wherein the content of the rubber is 1% by mass or more and 10% by mass or less with respect to the total amount of the material for the denture base. The material for a denture base according to any one of claims 1 to 6 , wherein the content of the acrylic resin is 90% by mass or more with respect to the total amount of the material for the denture base. A denture base containing the material for the denture base according to any one of claims 1 to 7 . A denture having a denture bed according to claim 8 and an artificial tooth fixed to the denture base. A method for manufacturing a denture base, which comprises a cutting step of cutting the material for the denture base according to any one of claims 1 to 7 to obtain a denture base. A cutting process for obtaining a denture base by cutting the material for the denture base according to any one of claims 1 to 7 .
The fixing step of fixing the artificial tooth to the denture base and
A method for manufacturing a denture with a floor.

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