Dental blocks and dental blocks

Abstract

A dental block material containing polyether ether ketone and an inorganic filler, the inorganic filler being contained in the dental block material at a proportion of 10 mass% or more and less than 30 mass%, the dental block material having a melt viscosity of 450 to 690 Pa-sec at a temperature of 380°C and a shear rate of 1216 (sec ‑1 ).

Description

Technical Field

[0001] This disclosure relates to dental blocks and dental materials. Background Technology

[0002] Previously, dental blocks using thermosetting resin in a metal base could be CAD / CAM machined. CAD / CAM machining refers to machining using CAD (Computer-Aided Design) and CAM (Computer-Aided Manufacturing). CAD is a system for designing structures using computers, and CAM is a system for generating machining data based on shape data obtained from CAD. However, dental blocks using thermosetting resin are difficult to machine using CAD / CAM. Furthermore, CAD / CAM machined products obtained from dental blocks using these materials are hard, brittle, and easily scratched.

[0003] To address this issue, Patent Document 1 discloses a dental block formed from a thermoplastic resin with a Vickers hardness, flexural strength, and flexural modulus within a specified range.

[0004] Patent document 2 discloses a resin composite material, characterized in that it contains 100 parts by volume of polyaryletherketone resin with a melt viscosity of 210 to 350 Pa·sec at a temperature of 370 degrees and a shear rate of 1220 (1 / s) and 20 to 60 parts by volume of inorganic particles.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2022-119683

[0008] Patent Document 2: International Publication No. 2015 / 170649 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, neither Patent Document 1 nor Patent Document 2 explored the concept of balancing machinability and toughness in dental blocks. Machinability refers to the property of producing fine, scattered chips during the machining of dental blocks. By ensuring machinability, the surface of machined dental blocks, such as dental block molded products, can be made smooth.

[0011] Furthermore, if the dental block has high toughness, the processed dental block will not easily break when worn on the patient's teeth, and the processed dental block can be used for a long time.

[0012] The problem of this disclosure is to provide a dental block that provides both machinability and toughness.

[0013] Solution for solving the problem

[0014] This disclosure covers the following content.

[0015] [1] A dental block comprising polyetheretherketone and inorganic filler, wherein the inorganic filler comprises 10% by mass or more and less than 30% by mass, and the dental block is subjected to a temperature of 380°C and a shear rate of 1216 sec. -1 The melt viscosity at ) is 450–690 Pa·sec.

[0016] [2] The dental block according to [1], wherein the inorganic filler is inorganic particles.

[0017] [3] The dental block 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.

[0018] [4] The dental block according to any one of [1] to [3], wherein the proportion of the polyether ether ketone in the dental block is 70 to 80 by mass.

[0019] [5] The dental block according to any one of [1] to [4], wherein the polyetheretherketone is subjected to a temperature of 380°C and a shear rate of 1216 sec. -1 The melt viscosity at ) is 370–530 Pa·sec.

[0020] [6] A dental block having a block portion and a pin portion, the block portion and the pin portion comprising dental block material according to any one of [1] to [5].

[0021] [7] According to the dental block of [6], when the dental block is cut to obtain a test piece with a cut portion, the linear roughness of the cut portion of the test piece relative to the direction of the cut processing is 0.030 or less.

[0022] [8] The dental block according to [6] or [7], wherein the fracture strain is 7.0 or more in the tensile strength test of the dental block.

[0023] Invention Effects

[0024] According to this disclosure, a dental block material can be provided that provides both machinability and toughness. Attached Figure Description

[0025] Figure 1 This is a perspective view of a dental block as one embodiment of the present disclosure. Detailed Implementation

[0026] The present disclosure will now be described based on specific embodiments. It should be noted that, in this specification, when the lower limit and upper limit of a numerical range are described separately, the numerical range can be set as a combination of any lower limit and any upper limit. In this disclosure, the numerical range represented by "A~B" refers to a numerical range that includes both the lower and upper limits as endpoints.

[0027] In this specification, a dental block refers to a resin-containing block used in CAD / CAM processing. By processing the dental block using CAD / CAM, dental restorations known as dental block molded articles (also called dental crowns) can be manufactured. These dental block molded articles are used, for example, to treat cavities by repairing the affected area of ​​the tooth after the decayed portion has been removed. Their primary purpose is for dental treatment.

[0028] In this specification, dental block refers to the material used in the manufacture of dental blocks. Additionally, dental block may also be referred to as a dental block composition.

[0029] The dental block disclosed herein contains polyetheretherketone (PEEK) and inorganic filler. The proportion of inorganic filler in the dental block (hereinafter also referred to as the inorganic filler content) is 10% by mass or more and less than 30% by mass. Furthermore, the dental block is subjected to a temperature of 380°C and a shear rate of 1216 sec. -1 The melt viscosity at this temperature is 450–690 Pa·sec. If the content ratio of inorganic filler and the melt viscosity of the dental block are within the above range, then a dental block that can provide a dental block that balances machinability and toughness is obtained.

[0030] The reason why a dental block can provide a dental block that balances machinability and toughness is not yet clear, but the inventors speculate as follows.

[0031] If the inorganic filler content is less than 10% by mass, the resin block becomes soft, and the machinability of the dental block decreases. If the inorganic filler content is 30% by mass or more, the dental block becomes brittle, and its toughness becomes insufficient. Furthermore, if the melt viscosity of the dental block is less than 450 Pa·sec, the compressive strength of the dental block becomes low, and its toughness becomes insufficient. In addition, if the melt viscosity of the dental block exceeds 690 Pa·sec, its fluidity decreases, and the manufacturability of the dental block decreases.

[0032] Therefore, it is believed that by controlling the content ratio of inorganic fillers and the melt viscosity of the dental block within the above range, a dental block that can provide both easy machinability and toughness can be achieved.

[0033] As mentioned above, dental blocks are subjected to a temperature of 380°C and a shear rate of 1216 sec. -1 The melt viscosity at this temperature is 450–690 Pa·sec. More preferably, it is 500–670 Pa·sec, and more preferably 550–620 Pa·sec. Within this range, it is easy to produce dental blocks that provide both machinability and toughness. Furthermore, if the melt viscosity is measured at 380°C, stable melt viscosity measurements can be easily performed.

[0034] The melt viscosity of dental blocks can be adjusted by changing the melt viscosity of the PEEK used and by changing the proportion of inorganic fillers in the dental blocks. Furthermore, the method for determining the melt viscosity of dental blocks is described later.

[0035] Polyetheretherketone (PEEK) at 380°C and a shear rate of 1216 sec -1 The melt viscosity at the specified temperature is preferably 370–530 Pa·sec. More preferably, it is 375–500 Pa·sec, and even more preferably, it is 380–480 Pa·sec. By using these ranges, the melt viscosity of the dental block can easily be within these ranges. Furthermore, if the melt viscosity is measured at 380°C, stable melt viscosity measurements can be easily performed.

[0036] The melt viscosity of PEEK can be adjusted by changing the molecular weight of polyetheretherketone. Furthermore, an example of PEEK with a melt viscosity within the aforementioned range is VESTAKEEP (registered trademark) L4000G (manufactured by EVONIK). The method for determining the melt viscosity of PEEK will be described later.

[0037] The proportion of polyetheretherketone in dental blocks is not particularly limited, but is preferably 70-90% by mass, more preferably 75-85% by mass, and even more preferably 75-80% by mass.

[0038] As described above, the inorganic filler content in the dental block is 10% by mass or more and less than 30% by mass. Furthermore, 15% to 25% by mass is preferred, and 20% to 25% by mass is more preferred. Within the above range, it is easy to obtain a dental block that provides further improved machinability. When the dental block contains multiple inorganic fillers, the above-mentioned inorganic filler content is the total content of the multiple inorganic fillers.

[0039] The proportion of inorganic fillers in dental blocks can be adjusted by changing the amount of inorganic fillers added during the manufacturing process. The proportion of inorganic fillers can be determined by thermogravimetric analysis (TG).

[0040] 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, and yellow iron oxide. Additionally, sulfates such as calcium sulfate and barium sulfate are also preferred.

[0041] From the perspective of making the color of the dental block appropriate, it is more preferable to select one or more of the group consisting of titanium oxide, barium titanate, barium sulfate, and yellow iron oxide.

[0042] Inorganic fillers may contain inorganic substances other than those mentioned above. Examples of inorganic substances other than those mentioned above include praseodymium salts such as praseodymium chloride (III); erbium salts such as erbium chloride, erbium nitrate, erbium fluoride, and erbium oxalate; and manganese pink, which contains manganese dissolved in alumina.

[0043] Furthermore, inorganic fillers are preferably inorganic particles. If the inorganic filler is inorganic particles, it is easy to produce dental blocks that can provide both machinability and toughness.

[0044] The aspect ratio of the inorganic filler is not particularly limited, but is preferably 5 or less. The lower limit is not particularly limited, but examples include 1 or more and 5 or less. Within this range, it is easy to produce dental block materials that provide both machinability and toughness.

[0045] Dental blocks may contain known additives. Examples of additives include, for instance, antioxidants and UV absorbers.

[0046] There is no particular limitation on the manufacturing method of dental blocks. For example, dental blocks can be manufactured by mixing the aforementioned polyetheretherketone (PEEK) and inorganic filler in a container while heating. That is, the manufacturing method of dental blocks preferably includes a step of heating and mixing the PEEK and inorganic filler.

[0047] Alternatively, well-known methods can be used to manufacture dental blocks.

[0048] A dental block of one embodiment of this disclosure is illustrated using the accompanying drawings.

[0049] Dental block 80 has a block portion 81 and a pin portion 82 ( Figure 1 The dental block is preferably a molded product of the dental block material of this disclosure. That is, preferably the block portion 81 and the pin portion 82 comprise the dental block material of this disclosure.

[0050] Block 81 is a part of a molded product that is formed through CAD / CAM processing. The shape of block 81 is not particularly limited; for example, it can be a cuboid, cube, cylinder, or sphere. For example, if the block shape is a cuboid... Figure 1 The height X is preferably 10mm to 20mm, the longitudinal length Y is preferably 10mm to 20mm, and the transverse length Z is preferably 15mm to 65mm.

[0051] There are no particular limitations on the use of block-shaped molded products. For example, they can be used to create bridge abutment teeth by cutting away caries in the patient's mouth, or to cover the abutment teeth from above. Furthermore, block-shaped molded products can also be used as fillings or bridges for teeth.

[0052] The pin 82 is used to mount the dental block onto a CAD / CAM machine. By having the pin 82 on the dental block 80, the dental block can be fixed to the CAD / CAM machine, and its position can be adjusted during machining. The shape of the pin is not particularly limited and can be a known shape such as a cylinder.

[0053] From a productivity point of view, dental blocks are preferably integrally molded articles using the dental block material of this disclosure, including the block portion and the pin portion.

[0054] In the tensile strength test of the dental block, the fracture strain is preferably 7.0 or higher, more preferably 8.0 or higher, and even more preferably 10.0 or higher. Within this range, the toughness of the dental block tends to be appropriate. If it is less than 7.0, the toughness tends to decrease. There is no particular upper limit to the fracture strain; for example, it can preferably be set to 7.0–17.0, 8.0–16.0, or 10.0–15.0. If the fracture strain exceeds 17.0, the accuracy during machining may sometimes decrease.

[0055] Fracture strain can be adjusted by the proportion of inorganic filler. Specifically, a higher proportion of inorganic filler tends to result in a lower fracture strain, while a lower proportion tends to result in a higher fracture strain. The method for determining the fracture strain of dental blocks is described later.

[0056] When a dental block is cut to obtain a test piece with a cut portion, the linear roughness (Rz) of the cut portion of the test piece relative to the direction of the cut portion is preferably 0.030 or less.

[0057] The incision machining was performed using NOTCHING TOOL A from Toyo Seiki. The dental block was then incised to obtain a test piece conforming to JIS K 7111-1 / 1eA. The incision machining of the dental block was performed as follows: a cutting edge (a standard accessory of NOTCHING TOOL A, model 7505269) was placed against the dental block at a right angle to its length and parallel to its thickness direction. The cutting edge was moved along the length of the dental block, cutting it into a V-shape to form the incision. That is, the incision extends along the length of the test piece, and the shape of the incision is V-shaped when viewed from the length direction of the test piece. When viewing the test piece from the thickness direction, the deepest part extending along the length direction of the test piece (the valley portion when viewing the test piece from the length direction) can be considered the apex of the incision.

[0058] Next, the linear roughness of the cut portion relative to the cutting direction is measured. Linear roughness is a specification of surface roughness, defined by JIS B 0601-2001. That is, a large linear roughness at the cut portion relative to the cutting direction indicates a rough surface at the cut portion. In other words, it indicates that cutting is difficult and that machinability is easily reduced. Conversely, it can be said that the smaller the linear roughness, the better the machinability. The specific measurement method is described later.

[0059] The linear roughness is more preferably 0.025 or less, further preferably 0.020 or less, and particularly preferably 0.014 or less. Within this range, the machinability of the dental block becomes suitable. If it exceeds 0.030, the machinability may sometimes decrease. The lower limit of the linear roughness is not particularly limited; for example, 0.000–0.030, 0.000–0.025, 0.005–0.020, and 0.005–0.014 are preferably listed. The value of the linear roughness can be adjusted by the content ratio of the inorganic filler. Specifically, if the content ratio of the inorganic filler increases, the value of the linear roughness tends to decrease. Conversely, if the content ratio of the inorganic filler decreases, the value of the linear roughness tends to increase.

[0060] The method for determining line roughness will be described later.

[0061] There is no particular limitation on the manufacturing method of the dental block. The dental block can be manufactured by molding the dental block material of this disclosure using known molding methods such as injection molding and extrusion molding. That is, the manufacturing method of the dental block preferably includes a step of molding the dental block material of this disclosure.

[0062] The following describes the methods for determining the physical properties of dental blocks and dental materials.

[0063] <Methods for determining the melt viscosity of dental blocks and polyetheretherketone>

[0064] The measurements were performed using a capillary rheometer from Toyo Seiki Co., Ltd., based on JIS K7199. For the test samples, the test temperature was 380℃ and the apparent shear rate was 1216 sec. -1 The apparent viscosity at which the sample is obtained is taken as the melt viscosity. Dental blocks or polyetheretherketone (PEEK) are used as the test specimens.

[0065] <Methods for determining fracture strain of dental blocks>

[0066] The toughness of a dental block can be evaluated by measuring its tensile strength. The tensile strength of a dental block is determined according to the following steps.

[0067] Based on JIS K7161, measurements were performed using the Autograph AG-X Plus manufactured by Shimadzu Corporation. The test speed was set to 50 mm / min. Regarding the test specimen, a multi-purpose test piece (Type A1) with a thickness of 4 mm was obtained from dental block material used as the raw material for the dental block. This multi-purpose test piece was the dumbbell-shaped tensile test piece described in JIS K7139. The test results obtained from this test specimen were taken as the tensile strength of the dental block.

[0068] <Methods for determining line roughness>

[0069] The determination of line roughness is carried out according to the following steps.

[0070] 1. A multipurpose test piece (Type A1) is obtained from dental blocks used as raw materials for dental blocks as a test specimen. The multipurpose test piece is the dumbbell-shaped tensile test piece described in JIS K 7139.

[0071] 2. Use Toyo Seiki NOTCHING TOOL A to cut the dumbbell test pieces to produce test pieces with cut sections that conform to JIS K7111-1 / 1eA.

[0072] 3. Use the KEYENCE VR-3000 one-step 3D shape measuring machine to acquire concave and convex images including the cut area.

[0073] 4. Based on the acquired convex-concave image, calculate the line roughness of the cut portion relative to the cutting direction. Specifically, when observing the convex-concave image from the thickness direction of the test piece, a straight line extending along the length direction of the test piece is set along the top of the cut portion. Then, when observing the convex-concave image from the thickness direction of the test piece, five straight lines are set at 0.06 mm intervals on each side of the straight line along the top of the cut portion, for a total of 11 straight lines. Then, the line roughness of the cut portion on each straight line is measured. At this time, the range of the cut portion 0.5 mm from each end in the cutting direction is removed from the line roughness measurement object, and the remaining part is used as the measurement object. The arithmetic mean of the obtained line roughness is taken as the line roughness of the cut portion relative to the cutting direction.

[0074] In addition, the evaluation criteria for machinability are as follows.

[0075] A: The line roughness value is below 0.014.

[0076] B: The line roughness value is greater than 0.014 and less than 0.030.

[0077] C: The line roughness value is greater than 0.030 and less than 0.050.

[0078] D: The line roughness value exceeds 0.050.

[0079] The various components and combinations in each embodiment are merely examples, and appropriate additions, omissions, substitutions, and other modifications to the components can be made without departing from the spirit of the invention. This disclosure is not limited to the embodiments but only to the claims.

[0080] Example

[0081] The present disclosure will now be described in detail with reference to embodiments. However, the present disclosure is not limited to the embodiments described below.

[0082] [Example 1]

[0083] 100 parts by weight of polyetheretherketone (VESTAKEEP (registered trademark) L4000G, manufactured by EVONIK) as the base resin were pulverized to an average particle size d50 = 10 μm to obtain PEEK pulverized material. Then, 10 parts by weight of titanium dioxide as an inorganic filler were mixed into the PEEK pulverized material through biaxial mixing to produce dental blocks.

[0084] The obtained dental block was thermally melted and then injection molded to obtain a dental block with a cuboid shape for the block portion and a cylindrical shape for the pin portion. The processing time is shown in Table 1. The above-mentioned measurements were performed on the dental block. The resulting physical properties are shown in Table 1.

[0085] [Examples 2-6]

[0086] The types and proportions of inorganic fillers are listed in Table 1. Otherwise, dental blocks and dental materials were obtained in the same manner as in Example 1. The physical properties of the obtained dental blocks are shown in Table 1.

[0087] [Comparative Examples 1-3]

[0088] The types of matrix resin, inorganic fillers, and their proportions are listed in Table 1. Otherwise, dental blocks and dental materials were obtained in the same manner as in Example 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.

[0089] [Table 1]

[0090]

[0091] Industrial availability

[0092] According to this disclosure, a dental block material can be provided that provides both machinability and toughness. That is, the dental block material of this disclosure can be used in the manufacture of dental blocks.

Claims

1. A dental block comprising polyetheretherketone (PEEK) and inorganic fillers, The inorganic filler in the dental block contains more than 10% by mass and less than 30% by mass. The dental block was subjected to a temperature of 380°C and a shearing speed of 1216 seconds. -1 The melt viscosity is 450–690 Pa·sec.

2. The dental block according to claim 1, wherein, The inorganic filler is composed of inorganic particles.

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

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

5. The dental block according to any one of claims 1 to 4, wherein, The polyetheretherketone was subjected to a temperature of 380°C and a shear rate of 1216 sec. -1 The melt viscosity is 370–530 Pa·sec.

6. A dental block, said dental block having a block portion and a pin portion, The block portion and the pin portion comprise dental blocks according to any one of claims 1 to 5.

7. The dental block according to claim 6, wherein, When a test piece with an incision is obtained by making an incision in the dental block, the linear roughness of the incision of the test piece relative to the direction of the incision is 0.030 or less.

8. The dental block according to claim 6 or 7, wherein, In the tensile strength test of the dental block, the fracture strain was 7.0 or higher.

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