Dental block material and dental block

Abstract

Provided is a dental block material containing poly(ether ether ketone) and an inorganic filler. The content ratio of the inorganic filler in the dental block material is not less than 10 mass% but less than 30 mass%, and the melt viscosity of the dental block material at a temperature of 380°C and a shear rate of 1216 (sec-1) is 450-690 Pa·sec.

Description

Dental block materials and dental blocks

[0001] The present disclosure relates to dental blocking materials and dental blocks.

[0002] Conventionally, dental blocks have been made using a metal base and thermosetting resin, and dental blocks made using this dental block material have been machined using CAD / CAM. CAD / CAM machining is a process that combines CAD (Computer Aided Design), a system that uses a computer to design structures, and CAM (Computer Aided Manufacturing), a system that converts the shape data obtained by CAD into data for machining. However, dental blocks made using thermosetting resin have been difficult to machine using CAD / CAM. Another issue is that CAD / CAM-machined products obtained from dental blocks made using this dental block material are hard but brittle and easily chipped.

[0003] To address these issues, Patent Document 1 discloses a dental block material made of a thermoplastic resin having a Vickers hardness, flexural strength, and flexural modulus within a predetermined range. Patent Document 2 discloses a resin composite material characterized by containing 100 parts by volume of a polyaryl ether ketone resin having a melt viscosity of 210 to 350 Pa·sec at a temperature of 370°C and a shear rate of 1220 (1 / s), and 20 to 60 parts by volume of inorganic particles.

[0004] JP 2022-119683 A International Publication No. 2015 / 170649

[0005] However, Patent Documents 1 and 2 did not consider a dental block that combines both machinability and toughness. Machinability refers to the property of producing small chips when machining a dental block. Machinability of a dental block allows for smooth surfaces of dental block workpieces, such as dental block molded products. Furthermore, if a dental block has high toughness, the dental block workpiece is less likely to break when attached to a patient's teeth, allowing for long-term use.

[0006] An object of the present disclosure is to provide a dental block material that can provide a dental block that is both easy to cut and tough.

[0007] The present disclosure relates to the following: [1] A dental block material containing polyether ether ketone and an inorganic filler, wherein the content of the inorganic filler in the dental block material is 10% by mass or more and less than 30% by mass, and the dental block material is subjected to a temperature of 380°C and a shear rate of 1216 (sec －１ ) is 450 to 690 Pa·sec. [2] The dental block material according to [1], wherein the inorganic filler is inorganic particles. [3] The dental block material according to [1] or [2], wherein the inorganic filler is one or more selected from the group consisting of titanium oxide, barium sulfate, barium titanate, and yellow iron oxide. [4] The dental block material according to any one of [1] to [3], wherein the content of the polyether ether ketone in the dental block material is 70 to 80 mass %. [5] The polyether ether ketone is melted at a temperature of 380°C, a shear rate of 1216 (sec) －１ [6] A dental block according to any one of [1] to [4], wherein the melt viscosity at 2000 kJ / min is 370 to 530 Pa·sec. [6] A dental block comprising a block portion and a pin portion, wherein the block portion and the pin portion comprise the dental block material according to any one of [1] to [5]. [7] The dental block according to [6], wherein, when the dental block is notched to obtain a test piece having a notch, the line roughness of the notch in the notch direction of the test piece is 0.030 or less. [8] The dental block according to [6] or [7], wherein, in a tensile strength test of the dental block, the breaking strain is 7.0 or more.

[0008] According to the present disclosure, a dental block material can be provided that can provide a dental block that has both free-cutting properties and toughness.

[0009] 1 is a perspective view of a dental block according to one aspect of the present disclosure; FIG.

[0010] The present disclosure will be described below based on specific embodiments. In this specification, when a numerical range is described with a lower limit and an upper limit separately, the numerical range can be a combination of any lower limit and any upper limit. In this disclosure, a numerical range expressed using "A to B" means a numerical range that includes the lower and upper limits, which are the endpoints.

[0011] As used herein, dental blocks refer to blocks containing resin for use in CAD / CAM processing. By subjecting dental blocks to CAD / CAM processing, dental prostheses called dental block molded products (also called crowns) can be manufactured. These dental block molded products can be used, for example, to treat caries in patients by drilling out the decayed portion and then placing the dental block molded product in the area of ​​the tooth to be restored, and are therefore primarily used for dental treatment. As used herein, dental block materials refer to materials used in the production of dental blocks. Dental block materials can also be referred to as dental block material compositions.

[0012] The dental block material of the present disclosure contains polyetheretherketone (PEEK) and an inorganic filler. The content of the inorganic filler in the dental block material (hereinafter simply referred to as the inorganic filler content) is 10% by mass or more and less than 30% by mass. The dental block material is then heated at a temperature of 380°C and a shear rate of 1216 (sec －１ When the content of the inorganic filler and the melt viscosity of the dental block material are within the above ranges, the dental block material can provide a dental block that is both easy to cut and tough.

[0013] Although it is unclear why the melt viscosity and inorganic filler content of the dental block material within the above ranges enable the provision of a dental block material that combines easy-to-cut properties with toughness, the inventors speculate as follows: If the inorganic filler content is less than 10% by mass, the resin block becomes soft, reducing the machinability of the dental block. If the inorganic filler content is 30% by mass or more, the dental block becomes brittle and its toughness becomes insufficient. If the melt viscosity of the dental block material is less than 450 Pa·sec, the compressive strength of the dental block decreases and its toughness becomes insufficient. If the melt viscosity of the dental block material exceeds 690 Pa·sec, the fluidity decreases, reducing the manufacturability of the dental block. Therefore, it is believed that the inorganic filler content and melt viscosity of the dental block material within the above ranges enable the provision of a dental block that combines easy-to-cut properties with toughness.

[0014] As described above, the temperature of the dental block material was 380°C, and the shear rate was 1216 (sec －１ ) is 450 to 690 Pa·sec. Also, 500 to 670 Pa·sec is preferable, and 550 to 620 Pa·sec is more preferable. By keeping the viscosity within the above range, a dental block material that can provide dental blocks that are both easy to cut and tough is likely to be obtained. Here, a melt viscosity measurement temperature of 380°C facilitates stable melt viscosity measurement. The melt viscosity of the dental block material can be adjusted by changing the melt viscosity of the PEEK used or by changing the inorganic filler content in the dental block material. The method for measuring the melt viscosity of the dental block material will be described later.

[0015] Polyether ether ketone temperature 380°C, shear rate 1216 (sec －１) is preferably 370 to 530 Pa·sec. Furthermore, 375 to 500 Pa·sec is more preferable, and 380 to 480 Pa·sec is even more preferable. By keeping the viscosity within the above range, the melt viscosity of the dental block material is likely to fall within the above range. Here, a melt viscosity measurement temperature of 380°C facilitates stable melt viscosity measurement. The melt viscosity of PEEK can be adjusted by changing the molecular weight of the polyether ether ketone. An example of a PEEK having a melt viscosity within the above range is VESTAKEEP (registered trademark) L4000G (manufactured by EVONIK). The method for measuring the melt viscosity of PEEK will be described later.

[0016] The content of polyether ether ketone in the dental block material is not particularly limited, but is preferably 70 to 90% by mass, more preferably 75 to 85% by mass, and even more preferably 75 to 80% by mass.

[0017] As described above, the inorganic filler content in the dental block material is 10% by mass or more and less than 30% by mass. It is preferably 15 to 25% by mass, and more preferably 20 to 25% by mass. This range makes it easier to provide a dental block material with improved machinability. When the dental block material contains multiple types of inorganic fillers, the inorganic filler content refers to the total content of the multiple types of inorganic fillers. The inorganic filler content in the dental block material can be adjusted by changing the amount of inorganic filler added when producing the dental block material. The inorganic filler content can be measured by thermogravimetry (TG).

[0018] The inorganic filler is not particularly limited, but is preferably an inorganic oxide such as silica, alumina, aluminosilicate glass, silica fiber, praseodymium oxide, erbium oxide, manganese oxide, titanium oxide, barium titanate, or yellow iron oxide. Sulfates such as calcium sulfate or barium sulfate are also preferred. Among these, one or more selected from the group consisting of titanium oxide, barium titanate, barium sulfate, and yellow iron oxide are more preferred, as they provide a suitable color for the dental block.

[0019] The inorganic filler may contain inorganic substances other than those mentioned above. Examples of inorganic substances other than those mentioned above include praseodymium salts such as praseodymium (III) chloride; erbium salts such as erbium chloride, erbium nitrate, erbium fluoride, and erbium oxalate; and manganese pink, a solid solution of manganese in aluminum oxide. Furthermore, the inorganic filler is preferably inorganic particles. When the inorganic filler is inorganic particles, a dental block material that can provide a dental block that combines easy-to-cut properties and toughness is likely to be obtained. The aspect ratio of the inorganic filler is not particularly limited, but is preferably 5 or less. The lower limit is not particularly limited, and examples include a range from 1 to 5. Within the above range, a dental block material that can provide a dental block that combines easy-to-cut properties and toughness is likely to be obtained.

[0020] The dental block material may contain known additives, such as antioxidants and ultraviolet absorbers.

[0021] The method for producing the dental block material is not particularly limited, but the dental block material can be produced, for example, by mixing the above-mentioned polyether ether ketone and inorganic filler in a container while heating. That is, the method for producing the dental block material preferably includes a step of heating and mixing the polyether ether ketone and inorganic filler. Other known methods can also be used to produce the dental block material.

[0022] A dental block according to one embodiment of the present disclosure will be described with reference to the drawings. Dental block 80 includes a block portion 81 and a pin portion 82 (FIG. 1). The dental block is preferably a molded product of the dental block material of the present disclosure. That is, the block portion 81 and the pin portion 82 preferably include the dental block material of the present disclosure.

[0023] The block portion 81 is a portion that will become a molded block portion product through CAD / CAM processing. The shape of the block portion 81 is not particularly limited and can be, for example, a rectangular parallelepiped, a cube, a cylinder, or a sphere. For example, when the shape of the block portion is a rectangular parallelepiped, the height X in FIG. 1 is preferably 10 mm to 20 mm, the vertical length Y is preferably 10 mm to 20 mm, and the horizontal length Z is preferably 15 mm to 65 mm. The method of using the molded block portion is not particularly limited, but for example, it can be used by drilling a cavity in a patient's oral cavity to prepare an abutment tooth and then placing the block portion over the abutment tooth. Alternatively, the molded block portion can be used as a dental filling or bridge.

[0024] The pin portion 82 is a portion used when attaching the dental block to a CAD / CAM processing machine. By providing the dental block 80 with the pin portion 82, the dental block can be fixed to the CAD / CAM processing machine and its position can be adjusted when processing the dental block. The shape of the pin portion is not particularly limited, and any known shape such as a cylindrical shape can be used.

[0025] From the viewpoint of productivity, the dental block is preferably an integrally molded product of the block portion and pin portion using the dental block material of the present disclosure.

[0026] In a tensile strength test of the dental block, the breaking strain is preferably 7.0 or more, more preferably 8.0 or more, and even more preferably 10.0 or more. Within the above range, the dental block is likely to have favorable toughness. If it is less than 7.0, the toughness is likely to be low. The upper limit of the breaking strain is not particularly limited, but it can be, for example, preferably 7.0 to 17.0, 8.0 to 16.0, or 10.0 to 15.0. If the breaking strain exceeds 17.0, the accuracy during cutting may decrease. The breaking strain can be adjusted by the inorganic filler content. Specifically, as the inorganic filler content increases, the breaking strain tends to decrease. Furthermore, as the inorganic filler content decreases, the breaking strain tends to increase. The method for measuring the breaking strain of a dental block will be described later.

[0027] When a dental block is notched to obtain a test specimen having a notch, the line roughness (Rz) of the notch in the direction of the notch is preferably 0.030 or less. To perform the notching, a Toyo Seiki NOTCHING TOOL A is used. The dental block is then notched to obtain a test specimen conforming to JIS K 7111-1 / 1eA. The notching of the dental block is performed by placing a notching cutting blade (model number 7505269, a standard accessory of the NOTCHING TOOL A) on the dental block so that it is perpendicular to the length of the dental block and parallel to the thickness direction, and then moving the cutting blade along the length of the dental block to cut the dental block into a V-shape, forming a notch. That is, the notch extends along the length of the test specimen, and the shape of the notch is V-shaped when viewed along the length of the test specimen. When the test piece is viewed in the thickness direction, the deepest part extending in the length direction of the test piece (the valley bottom when the test piece is viewed in the length direction) can be said to be the tip of the notch.

[0028] The linear roughness of the notch portion in the direction of the notch processing is then measured. Linear roughness is a standard for surface roughness and is defined in JIS B 0601-2001. In other words, a large linear roughness in the direction of the notch processing at the notch portion indicates a rough surface at the notch portion. This indicates that notch processing is difficult and that free-cutting is likely to be poor. Conversely, the smaller the linear roughness, the more likely it is that the free-cutting is excellent. Specific measurement methods will be described later. The linear roughness is more preferably 0.025 or less, even more preferably 0.020 or less, and particularly preferably 0.014 or less. Within the above range, the dental block has good free-cutting properties. If it exceeds 0.030, free-cutting properties may be reduced. While there is no particular lower limit for the linear roughness, preferred examples include 0.000 to 0.030, 0.000 to 0.025, 0.005 to 0.020, and 0.005 to 0.014. The line roughness value can be adjusted by the content ratio of the inorganic filler. Specifically, as the content ratio of the inorganic filler increases, the line roughness value tends to decrease. On the other hand, as the content ratio of the inorganic filler decreases, the line roughness value tends to increase. The method for measuring line roughness will be described later.

[0029] The method for manufacturing the dental block is not particularly limited, but the dental block can be manufactured, for example, by molding the dental block material of the present disclosure using a known molding method such as injection molding or extrusion molding. That is, the method for manufacturing the dental block preferably includes a step of molding the dental block material of the present disclosure.

[0030] The dental block material and the method for measuring the physical properties of the dental block will be described below.

[0031] <Method for measuring the melt viscosity of dental block material and polyether ether ketone> Measurement was performed using a capillary rheometer manufactured by Toyo Seiki Co., Ltd., based on JIS K7199. The test temperature for the measurement sample was 380°C, and the apparent shear rate was 1216 (sec －１ The apparent viscosity at this temperature is measured and used as the melt viscosity. Dental block material or polyether ether ketone is used as the measurement sample.

[0032] <Method for measuring the strain at break of a dental block> The toughness of a dental block can be evaluated by measuring the tensile strength of the dental block. The tensile strength of a dental block is measured using the following procedure. Measurements are made using an autograph AG-X Plus manufactured by Shimadzu Corporation based on JIS K7161. The test speed is 50 mm / min. A measurement sample is prepared from the dental block material, which is the raw material for the dental block, to obtain a multipurpose test piece (Type A1), which is a dumbbell-shaped tensile test piece as described in JIS K7139, with a test piece thickness of 4 mm. The measurement result obtained from this measurement sample is the tensile strength of the dental block.

[0033] <Method for Measuring Line Roughness> Line roughness is measured using the following procedure. 1. A multipurpose test piece (Type A1), which is a dumbbell-shaped tensile test piece as specified in JIS K 7139, is obtained as a measurement sample from a dental block material, which is the raw material for dental blocks. 2. The dumbbell test piece is notched using a Toyo Seiki Notching Tool A to prepare a test piece with a notch corresponding to JIS K 7111-1 / 1eA. 3. A Keyence One-Shot 3D Shape Measuring Instrument VR-3000 is used to obtain a topographical image including the notch. 4. From the obtained topographical image, the line roughness of the notch in the direction of the notch is determined. Specifically, when the topographical image is viewed from the thickness direction of the test piece, a straight line is drawn along the tip of the notch and extending in the length direction of the test piece. When the unevenness image is viewed from the thickness direction of the test piece, five straight lines are drawn on each side of the straight line along the tip of the notch at 0.06 mm intervals, for a total of 11 straight lines. The line roughness of the notch on each straight line is then measured. A 0.5 mm range from each end of the notch in the notch processing direction is excluded from the line roughness measurement, and the remaining area is used as the measurement target. The arithmetic mean value of the obtained line roughness is taken as the line roughness of the notch in the notch processing direction.

[0034] The evaluation criteria for machinability are as follows: A: Line roughness value is 0.014 or less. B: Line roughness value is greater than 0.014 and less than 0.030. C: Line roughness value is greater than 0.030 and less than 0.050. D: Line roughness value is greater than 0.050.

[0035] The configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible as appropriate within the scope of the spirit of the present invention. The present disclosure is not limited to the embodiments, but is limited only by the scope of the claims.

[0036] The present disclosure will be specifically described below with reference to examples, but the present disclosure is not limited to the aspects of the following examples.

[0037] [Example 1] 100 parts by mass of polyether ether ketone (VESTAKEEP (registered trademark) L4000G, manufactured by EVONIK) as a base resin was pulverized to an average particle size d50 of 10 μm to obtain a PEEK pulverized material. Subsequently, 10 parts by mass of titanium oxide as an inorganic filler was mixed with the PEEK pulverized material by biaxial kneading to obtain a dental block material. The obtained dental block material was injection-molded by thermal melting to obtain a dental block with a rectangular block portion and a cylindrical pin portion. The processing time was as shown in Table 1. The above-mentioned measurements were performed on the dental block. The obtained physical properties are shown in Table 1.

[0038] [Examples 2 to 6] Dental block materials and dental blocks were obtained in the same manner as in Example 1, except that the type and content of the inorganic filler were changed to those shown in Table 1. The physical properties of the obtained dental blocks are shown in Table 1.

[0039] Comparative Examples 1 to 3 Dental block materials and dental blocks were obtained in the same manner as in Example 1, except that the type of base resin and the type and content of the inorganic filler were as shown in Table 1. The physical properties of the obtained dental blocks are shown in Table 1. In the table, 2000G indicates VESTAKEEP (registered trademark) 2000G, manufactured by EVONIK.

[0040] According to the present disclosure, a dental block material can be provided that can provide dental blocks that have both free-machining ability and toughness. That is, the dental block material of the present disclosure can be used to manufacture dental blocks.

Claims

1. A dental block material containing polyetheretherketone and an inorganic filler, wherein the content ratio of the inorganic filler in the dental block material is 10% by mass or more and less than 30% by mass, and the melt viscosity of the dental block material at a temperature of 380 ° C and a shear rate of 1216 (sec －１ -1) is 450 to 690 Pa·sec.

2. The dental block material according to claim 1, wherein the inorganic filler is inorganic particles.

3. The dental block material according to claim 1 or 2, wherein the inorganic filler is one or more selected from the group consisting of titanium oxide, barium sulfate, barium titanate, and yellow iron oxide.

4. The dental block material according to any one of claims 1 to 3, wherein the content ratio of the polyetheretherketone in the dental block material is 70 to 80% by mass.

5. The melt viscosity of the polyetheretherketone at a temperature of 380°C and a shear rate of 1216 (sec －１ -1) is 370 to 530 Pa·sec. The dental block material according to any one of claims 1 to 4.

6. A dental block comprising a block portion and a pin portion, wherein the block portion and the pin portion contain the dental block material according to any one of claims 1 to 5.

7. The dental block according to claim 6, when a test piece having a notch portion is obtained by notch processing the dental block, the line roughness in the notch portion of the test piece with respect to the notch processing direction is 0.030 or less.

8. The dental block according to claim 6 or 7, wherein the breaking point strain is 7.0 or more in the tensile strength test of the dental block.

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