Molding tool and production method of dental processing blank

Abstract

To provide a molding tool and a production method of a dental processing blank which prevent occurrence of roughness on a surface of a cured body, even when the cured body is subjected to polymerization and curing at a high temperature increase rate for shortening a polymerization time.SOLUTION: A molding tool comprises: a cylindrical body 3d having openings 3b, 3c on one end and the other end, respectively; and a pair of holding members 3a, 4 for closing the openings 3b, 3c on the one end and the other end of the cylindrical body 3d to hold a fluidity paste P filled in the cylindrical body 3d and having thermal polymerization curing property. The cylindrical body 3d can be divided into one or more cylindrical body units 3d1 forming the cylindrical body 3d in an axial direction of the cylindrical body 3d, and a thickness of the cylindrical body 3d is set to a thickness at which the cylindrical body is deformed while tightly contacting the fluidity paste P, following to polymerization shrinkage of the fluidity paste P filled in the cylindrical body 3d.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to a forming die and a manufacturing method for a dental processing blank.

Background Art

[0002] In the field of dental treatment, in order to repair tooth defect sites, non-metallic dental prostheses that are free from concerns about metal allergies and have excellent aesthetics are used. Dental prostheses can be easily manufactured from dental processing blanks made of non-metallic materials using a CAD / CAM system.

[0003] Patent Document 1 discloses a CAD / CAM system. The CAD / CAM system is a system that cuts a dental processing blank using a CAD / CAM device based on computer-aided design (CAD) and computer-aided manufacturing (CAM) technologies from a captured image inside the oral cavity.

[0004] Also, a dental processing blank is a workpiece (hereinafter, also referred to as a "mill blank") that can be attached to a cutting machine of a CAD / CAM system. The dental processing blank has a cut portion and a holding portion that can attach the cut portion to a cutting machine.

[0005] In recent years, a mill blank (hereinafter, also referred to as an "HR mill blank") having a cut portion made of a "hybrid resin" (hereinafter, also referred to as "HR"), which is a composite material in which inorganic fillers (inorganic fillers) are dispersed at a high density in a polymerizable monomer matrix, has rapidly spread.

[0006] As a method for manufacturing the cut portion of an HR mill blank, an HR raw material paste made of a polymerization-curable composition containing a polymerizable monomer, an inorganic filler, and a polymerization initiator is polymerized and cured by applying pressure and heat in a mold having a shape corresponding to a desired cut portion shape such as a rectangular parallelepiped shape, a cylindrical shape, a plate shape, or a disk shape. This method is generally used.

[0007] Patent Document 1 discloses a manufacturing method as described above. That is, the method for manufacturing a dental resin block disclosed in Patent Document 1 injects a material before curing that will become a dental resin block into a mold equipped with means for equalizing the internal and external pressures formed by a thermoplastic resin or a silicone resin. Next, the mold into which the material before curing that will become a dental resin block is injected is placed in a container capable of applying a predetermined pressure to the whole, and the mold and the material before curing injected into the mold are pressurized at 1.0 MPa or more. Finally, the mold and the material before curing injected into the mold are heated at 60°C or more.

[0008] Patent Document 1 discloses that in this manufacturing method, since the composition before curing is placed in a mold that is not made of metal, placed in a container capable of applying a predetermined pressure to the whole of the mold, pressurized and heated, and polymerized so that the internal and external pressures of the mold become equal, generation of bubbles in the block and generation of cracks during processing can be suppressed.

[0009] However, according to the method described in Patent Document 1, in order to fill the mold with the HR raw material paste without gaps, it is necessary to gently inject the paste using a syringe or the like. Further, when using a HR raw material paste with low fluidity having a high filler filling rate for improving physical properties, the HR raw material paste may not flow into the corner portions of the mold, resulting in filling failure, and quantitative filling into the mold may be difficult.

[0010] On the other hand, a method for satisfactorily filling a mold with a low-fluidity HR raw material paste having a high filler filling rate is known. That is, Patent Document 2 discloses a method for manufacturing a dental processing blank having a multilayer structure without causing defects such as turbulence and voids at the interface of each layer even when using a fluid paste having a high inorganic filler filling rate and low fluidity. That is, "In a method for manufacturing a dental processing blank having a multilayer structure including at least a first layer and a second layer, a first mold unit, which is a mold unit having at least one open surface, is filled with a first fluid paste made of a curable composition and having a desired shape retention property, in which the first layer is formed. At the same time, a second mold unit, which is a mold unit having at least one open surface, is filled with a second fluid paste made of a curable composition and having a desired shape retention property, in which the second layer is formed. A filling step, in which the openings of the first mold unit and the second mold unit are aligned, and the first fluid paste and the second fluid paste are brought into close contact and joined to obtain a laminate having a multilayer structure including at least a first layer made of the first fluid paste and a second layer made of the second fluid paste. And a curing step of curing the laminate having the multilayer structure, a method for manufacturing a dental processing blank having a multilayer structure, characterized by including the above steps." is disclosed.

[0011] The filling method of the HR raw material paste adopted in the above method is such that the lower end opening of the cylindrical body, which is a mold unit, is used as the supply side opening, and a movable plate is inserted into the columnar cavity so as to be movable forward and backward, and the supply side opening is closed by the movable plate. In this state, the mold unit is set on the filling tool, and a predetermined amount of HR raw material paste is filled into the cylindrical body by pushing up the movable bottom plate from below. Thereby, even when using a fluid paste with low fluidity, since the movable plate rises from below in the columnar cavity of the cylindrical body, no filling defect occurs at the corner portion.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0013] The method described in Patent Document 2 relates to a method for manufacturing a dental processing blank having a multilayer structure. However, if the filling method described in the document is adopted, a machined part having a single-layer structure can also be produced. For example, after the above filling operation is completed, the cylindrical body (mold unit) is removed from the filling tool and turned upside down. Subsequently, polymerization is carried out in a bottomed mold composed of a mold unit having the movable bottom plate as the bottom with the HR raw material paste filled therein, whereby a machined part having a single-layer structure can be produced.

[0014] However, if the temperature increase rate is increased for polymerization curing in order to shorten the polymerization time after the HR raw material paste is filled into the bottomed mold, roughness may occur on the surface of the cured body. This is the same even when the method disclosed in Patent Document 2 is adopted.

[0015] The present invention has been made in view of the above circumstances, and an object thereof is to provide a molding die and a manufacturing method for a dental processing blank in which roughness does not occur on the surface of the cured body even when polymerization curing is performed by increasing the temperature increase rate in order to shorten the polymerization time.

Means for Solving the Problems

[0016] A molding die for a dental processing blank according to one aspect of the present invention is a molding die including: a cylindrical body having openings at one end and the other end; and a pair of holding members that hold a fluid paste having thermopolymerization curability filled inside the cylindrical body by closing the openings at one end and the other end of the cylindrical body, wherein the cylindrical body is dividable in the axial direction of the cylindrical body into one or more cylindrical body units, and the thickness of the cylindrical body is set to a thickness that deforms while remaining in close contact with the fluid paste as the fluid paste filled inside the cylindrical body undergoes polymerization shrinkage.

[0017] Further, in the above-described invention, the cylindrical body conforms to JIS K7206 and is composed of a thermoplastic resin having a Vicat softening temperature measured at a load of 5 kgf / cm 2 in the range of 70 to 110°C, and the minimum thickness of the cylindrical body is 0.5 to 1.5 mm.

[0018] Further, in the above-described invention, the cylindrical body has a reinforcing portion that keeps the distance between one end and the other end constant.

[0019] Further, in the above-described invention, the cylindrical body has thickened portions with increased thickness at one end and the other end compared to other regions.

[0020] Further, in the above-described invention, the cylindrical body has a double structure including a first cylindrical portion having a thickened portion and a second cylindrical portion connected only at one end and the other end of the first cylindrical portion on the outer peripheral side of the first cylindrical portion.

[0021] Further, in the above-described invention, at least one of the pair of holding members is a movable plate that is inserted into the opening at the other end and is slidable inside the cylindrical body while remaining in close contact with the fluid paste as the fluid paste polymerizes and shrinks.

[0022] Further, in the above-described invention, one of the pair of holding members is a movable plate that is inserted into the opening at the other end and is slidable inside the cylindrical body while remaining in close contact with the fluid paste as the fluid paste polymerizes and shrinks, and the other is a deformable sheet-like member that remains in close contact with the paste joint surface of the fluid paste exposed at the opening at one end.

[0023] A method for manufacturing a dental processing blank having a machined portion composed of a hybrid resin according to one aspect of the present invention includes a raw material preparation step of preparing a fluid paste having thermopolymerization curability containing a polymerizable monomer, an inorganic filler, and a thermal polymerization initiator, which are raw materials of the hybrid resin; using a filling tool having a filling plate having a flat support surface on the upper surface, an opening as a filling nozzle provided on the support surface, and a paste flow path formed inside the filling plate and guiding the fluid paste toward the opening, placing the mold according to claim 7 with the sheet-like member not attached and the movable plate inserted so as to close the opening at one end of the cylindrical body at a position where the movable plate faces at least the support surface including the opening of the filling tool, holding the mold so as not to move, and then discharging the fluid paste from the filling nozzle and sliding the movable plate upward toward the other end while pushing it up to fill the mold with the fluid paste; a covering step of sliding the mold filled with the fluid paste on the support surface to a region not overlapping with the opening and then removing it from the filling tool, turning the opening at one end of the cylindrical body upward, covering the sheet-like member so as to be in close contact with the fluid paste at the opening at one end, and bringing the paste joint surface of the sheet-like member and the fluid paste into close contact; and a curing step of curing the fluid paste filled in the mold.

[0024] A method for manufacturing a dental processing blank having a machined part composed of a two-layer hybrid resin according to one aspect of the present invention includes a raw material preparation step of preparing a first fluid paste and a second fluid paste having different compositions and thermopolymerization curability, which are raw materials of the hybrid resin forming each layer of the machined part, and containing a polymerizable monomer, an inorganic filler, and a thermal polymerization initiator; a mold unit preparation step of preparing a cylindrical body that can be divided into two cylindrical body units, and a molding die according to claim 6 in which a pair of holding members are both movable plates, dividing the cylindrical body into two cylindrical body units, and inserting one movable plate into the opening at one end of each cylindrical body unit to prepare a first molding die unit and a second molding die unit; a filling step of using a filling tool having a filling plate having a flat support surface on the upper surface, an opening as a filling nozzle provided on the support surface, and a paste flow path formed inside the filling plate and guiding the fluid paste toward the opening, filling the first fluid paste into the first molding die unit and filling the second fluid paste into the second molding die unit. In the filling step, the first molding die unit and the second molding die unit are placed at positions where the movable plate faces at least the support surface including the opening of the filling tool, held so that the first molding die unit and the second molding die unit do not move, and then the first fluid paste and the second fluid paste are respectively discharged from the filling nozzle and slid while pushing up the movable plate toward the other end, filling the first fluid paste into the first molding die unit and filling the second fluid paste into the second molding die unit, and forming a paste joint surface that is planar or convex curved outward in the shape of a cylindrical body on the first fluid paste and the second fluid paste. The manufacturing method further includes a lamination step of laminating the first molding die unit and the second molding die unit having the paste joint surface so that the central axes coincide, and closely adhering the first fluid paste and the second fluid paste by overlapping the paste joint surfaces with each other to form a laminate of the fluid paste, and filling the laminate into a mold composed of a cylindrical body whose both ends are closed by a pair of support members composed of a pair of movable plates; and a curing step of curing the laminate of the fluid paste filled in the mold obtained by the lamination step.

[0025] A method for manufacturing a dental blank having a machined portion composed of a hybrid resin having n layers, where n is an integer of 3 or more, according to one aspect of the present invention, includes a raw material preparation step of preparing n kinds of fluid pastes corresponding to the n layers, which are different in composition from each other and have thermopolymerization curability, and contain a polymerizable monomer, an inorganic filler, and a thermal polymerization initiator, which are raw materials of the hybrid resin forming each layer of the machined portion; a mold unit preparation step of preparing a cylindrical body that can be divided into n cylindrical body units corresponding to the n layers, and an n-layer mold unit composed of a first mold unit to an n-th mold unit, in which one movable plate is inserted into the opening at one end of each divided cylindrical body unit. When the n cylindrical body units are connected to form a cylindrical body, they are numbered and divided so that the cylindrical body unit located at one end becomes the first cylindrical body and the cylindrical body unit located at the other end becomes the n-th cylindrical body. A filling step of filling the inside of the n mold units with one kind of each of the n kinds of fluid pastes different in type from each other using a filling tool having a filling plate having a flat support surface on the upper surface, an opening as a filling nozzle provided on the support surface, and a paste flow path formed inside the filling plate and guiding the fluid paste toward the opening. In the filling step, after placing each of the n mold units at a position where the movable plate faces the support surface including at least the opening of the filling tool and holding each mold unit so that it does not move, the fluid paste to be filled is discharged from the filling nozzle, and the movable plate is slid while being pushed upward toward the other end to fill each mold unit with each fluid paste, and each fluid paste forms a planar or convex curved surface paste joint surface outward of the cylindrical body. The manufacturing method includes laminating the first mold unit and the second mold unit having a paste joint surface so that the central axes coincide, and bringing the paste joint surfaces into contact with each other to closely adhere the fluid pastes to each other to form a laminate of the fluid pastes. After filling the inside of the connection body of the first cylindrical body unit and the second cylindrical body unit, the ends of which are closed by a pair of support members composed of a pair of movable plates, with the laminate,The first lamination step of removing only the movable plate of the second cylindrical body unit to form a paste joint surface that is flat or convexly curved outward from the connected body with the fluid paste, the connected body with the joint surface formed, and the third molding die unit with the connecting surface formed are laminated so that the central axes coincide, and the fluid pastes are brought into close contact with each other by overlapping the paste joint surfaces, forming a laminate of the fluid paste composed of three layers and filling the inside of the connected body of the first to third cylindrical bodies closed at both ends by a pair of support members composed of a pair of movable plates with the laminate, and then only removing the movable plate of the third molding die unit to form a paste joint surface that is flat or convexly curved outward from the connected body with the fluid paste. The operation of repeating this until a laminate of the fluid paste composed of (n - 1) layers is filled in the connected body of the first to (n - 1) molding die units and a connected body with the paste joint surface formed is obtained, the connected bodies of the first to (n - 1) molding die units and the nth molding die unit are laminated so that the central axes coincide, and the fluid pastes are brought into close contact with each other by overlapping the paste joint surfaces, forming a laminate of the fluid paste composed of n layers and filling the inside of the molding die composed of a cylindrical body closed at both ends by a pair of support members composed of a pair of movable plates with the laminate in the final lamination step, and a curing step of curing the laminate of the fluid paste filled in the molding die obtained in the final lamination step are further included.

Effect of the Invention

[0026] According to the present invention, it is possible to provide a molding die and a manufacturing method for a dental processing blank in which the surface of the cured body does not become rough even when polymerization curing is performed by increasing the heating rate to shorten the polymerization time.

Brief Description of the Drawings

[0027]

Figure 1

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Figure 15

Mode for Carrying Out the Invention

[0028] When the present inventors manufacture a dental blank having a multilayer structure by the manufacturing method disclosed in Patent Document 2, or when a single-layer structure dental blank is manufactured by adopting the above-described method using the filling method disclosed in Patent Document 2, the heating rate is increased and polymerization curing is performed. Then, the cause of the gap generated between the HR raw material paste and the inner wall surface of the mold was examined.

[0029] As a result, it was revealed that a smooth surface is obtained on the bottom and top surfaces of the cured body, and surface roughness is a problem peculiar to the side surfaces. Therefore, it was considered that the reason might be that the polymerization shrinkage of the HR raw material paste could not be followed in the polymerization step due to the difference between the cylindrical body constituting the side surface of the molding die and the movable plate or sheet covering the bottom and top surfaces.

[0030] That is, when polymerization shrinkage occurs, the movable plate and the sheet can move or deform following this, while the cylindrical body cannot deform following the polymerization shrinkage. For this reason, a gap is generated between the HR raw material paste and the inner wall surface of the cylindrical body, and it was considered that residual air might invade there, and furthermore, surface roughness might occur due to the accompanying polymerization inhibition.

[0031] Therefore, upon further examination, it was found that by making the wall thickness of the cylindrical body thinner so that it can follow the polymerization shrinkage, the occurrence of the above problem can be prevented, and the present invention was thus completed.

[0032] Hereinafter, the molding die and manufacturing method of the dental processing blank 1 according to the present embodiment will be described with reference to the drawings.

[0033] First, after explaining the raw materials used in the manufacturing method of the dental processing blank 1 using the molding die according to the present embodiment, each step in the embodiment of the present invention will be described with reference to the drawings.

[0034] In this specification, unless otherwise specified, the notation "x to y" using numerical values x and y means "x or more and y or less". In such notation, when a unit is attached only to the numerical value y, the unit is also applied to the numerical value x. Further, in this specification, the term "(meth)acrylic" means both "acrylic" and "methacrylic". Similarly, the term "(meth)acrylate" means both "acrylate" and "methacrylate", and the term "(meth)acryloyl" means both "acryloyl" and "methacryloyl".

[0035] 1. Regarding the raw materials of the fluid paste P In the manufacturing method of this embodiment, as a raw material of a hybrid resin (hereinafter, unless otherwise specified, "HR" refers to a hybrid resin) constituting the work piece portion 1a having a single-layer structure, a curable composition containing a polymerizable monomer, an inorganic filler, and a thermal polymerization initiator is used as a fluid paste P (see FIG. 7 and the like). These components will be described below.

[0036] <Polymerizable monomer> As the polymerizable monomer for coincidence, it can be appropriately selected and used from radical polymerizable monomers such as (meth)acrylic compounds, cationic polymerizable monomers such as epoxy compounds and oxetane compounds, etc., but it is preferable to use (meth)acrylate-based polymerizable monomers. As the (meth)acrylate-based polymerizable monomer, it may be either a monofunctional polymerizable monomer or a polyfunctional polymerizable monomer, and may also have an acidic group or a hydroxyl group in the molecule, and may be either aromatic or aliphatic. Examples of the (meth)acrylate-based polymerizable monomer that can be preferably used for dental polymerizable hardened products include methyl (meth)acrylate, ethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (meth)acrylic acid, N-(meth)acryloylglycine, p-vinylbenzoic acid, 2-(meth)acryloyloxybenzoic acid, 6-(meth)acryloyloxyethylnaphthalene-1,2,6-tricarboxylic anhydride, 13-(meth)acryloyloxytridecane-1,1-dicarboxylic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, N-hydroxyethyl (meth)acrylamide, N,N-(dihydroxyethyl)(meth)acrylamide, 2,2-bis(methacryloyloxyphenyl)propane, 2,2-bis[(3-methacryloyloxy-2-hydroxypropyloxy)phenyl]propane, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1,6-bis(methacryloylethyloxycarbonylamino)trimethylhexane, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, neopentyl glycol dimethacrylate, 4,4-diphenylmethane diisocyanate, etc.

[0037] These (meth)acrylate-based polymerizable monomers may be used in combination of a plurality of types as necessary.

[0038] <Inorganic filler> As the inorganic filler, inorganic particles such as amorphous silica, silica-zirconia, silica-titania, silica-titania-barium oxide, silica-titania-zirconia, quartz, alumina, glass, and organic-inorganic composite fillers using these inorganic particles can be preferably used. For example, in order to obtain a dental polymerizable curable composition, particles of a composite inorganic oxide mainly composed of silica and zirconia, or silica and barium oxide, such as particles of silica-zirconia, silica-titania-barium oxide, silica-titania-zirconia, are preferably used because they have high X-ray contrast. The shape of the inorganic particles is not particularly limited, but when spherical particles are used, the cured body of the resulting paste-like polymerizable curable composition is particularly excellent in abrasion resistance, surface smoothness, and gloss persistence. Examples of the organic-inorganic composite filler include granular organic-inorganic composite fillers obtained by mixing the aforementioned inorganic particles and a polymerizable monomer, followed by polymerization and pulverization.

[0039] In order to improve the mechanical strength and water resistance, the above inorganic particles may be treated with a surface treatment agent typified by a silane coupling agent.

[0040] In order to obtain a dental polymerizable curable composition, the average primary particle diameter of the inorganic particles is preferably 0.001 μm or more and 3 μm or less, and more preferably 0.1 μm or more and 1.0 μm or less from the viewpoints of abrasion resistance, surface smoothness, and gloss persistence of the cured body. Further, it is preferable to contain fine inorganic particles having an average primary particle diameter of 0.1 to 1.0 μm in addition to the powder raw material, and it is preferably contained in an amount of 20 parts by mass or more, more preferably 30 parts by mass or more, based on 100 parts by mass of the total mass of the inorganic filler (including those in the form of organic-inorganic composite fillers). Further, the fine inorganic particles are more preferably spherical fine inorganic particles.

[0041] Such an average primary particle diameter is determined using a scanning electron microscope. Observe the particles with a scanning electron microscope, randomly select 30 or more particles in the unit visual field, and measure the primary particle diameter (maximum diameter) of each particle. The value obtained by dividing the total of the primary particle diameters by the number of selected particles is defined as the average primary particle diameter.

[0042] The compounding amounts of these inorganic fillers may be appropriately determined in consideration of the mechanical properties of the cured body. However, since the fluidity is low, generally, they are used in the range of 300 parts by mass or more and 740 parts by mass or less, preferably 360 parts by mass or more and 560 parts by mass or less, based on 100 parts by mass of the polymerizable monomer.

[0043] <Thermal polymerization initiator> The thermal polymerization initiator is not particularly limited as long as it has the function of polymerizing and curing the polymerizable monomer by heat. For example, peroxides such as benzoyl peroxide, p-chlorobenzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxydicarbonate, diisopropyl peroxydicarbonate; azo compounds such as azobisisobutyronitrile; boron compounds such as tributylborane, tributylborane partial oxide, sodium tetraphenylborate, sodium tetrakis(p-fluorophenyl)borate, triethanolamine salt of tetraphenylboric acid; barbituric acids such as 5-butylbarbituric acid, 1-benzyl-5-phenylbarbituric acid; sulfinates such as sodium benzenesulfinate, sodium p-toluenesulfinate, etc. can be preferably used. These polymerization initiators may be used alone, or two or more of them may be mixed and used. It is also possible to combine a plurality of initiators with different polymerization methods.

[0044] The compounding amount of the polymerization initiator may be selected as an effective amount according to the type, but it is usually in the ratio of 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the polymerizable monomer.

[0045] <Other components> Furthermore, in order to achieve the properties of the target dental processing blank 1, for example, colorants such as pigments, polymerization inhibitors, chain transfer agents, fluorescent agents, ultraviolet absorbers, antioxidants, antibacterial agents, X-ray contrast agents, etc., which are used as additives for HR of the HR mill blank 1, can be appropriately compounded.

[0046] 2. Manufacturing Method of This Embodiment (Single Layer) The manufacturing method of this embodiment is a method for manufacturing a dental processing blank 1 having a machined portion 1a made of a hybrid resin with a single-layer structure, and includes a raw material preparation step, a filling step, a covering step, and a curing step. Hereinafter, the HR mill blank 1 as the manufacturing object and each of the above steps will be described with reference to the drawings as appropriate.

[0047] (1) Regarding the HR mill blank 1 as the manufacturing object FIG. 1 shows a perspective view schematically showing a dental processing blank (HR mill blank) 1 having a machined portion 1a made of a hybrid resin with a single-layer structure, which is the manufacturing object of the manufacturing method of this embodiment. As shown in FIG. 1, a blank holding pin 2 is joined to the machined portion 1a, and by fixing the HR mill blank 1 to a cutting device using a CAD / CAM system using this blank holding pin 2 and performing cutting, for example, a dental prosthesis 10 for molars as shown in FIG. 2 can be manufactured.

[0048] (2) Regarding the raw material preparation step In the raw material preparation step, each material serving as a raw material for the hybrid resin, that is, a polymerizable monomer, an inorganic filler, a thermal polymerization initiator, and optional components blended as necessary are each weighed in a predetermined amount, and these components are kneaded to prepare a fluid paste P. In addition, at the time of preparation, it is preferable to subject the fluid paste P obtained after kneading to vacuum degassing to remove bubbles. The filling rate of the inorganic filler in the fluid paste P {the ratio (mass %) of the mass of the inorganic filler to the total mass of the polymerizable monomer and the inorganic filler contained in the fluid paste P. Hereinafter, also simply referred to as "inorganic filling rate".} is preferably 72 to 99% by mass, more preferably 75 to 95% by mass, and most preferably 78 to 90% by mass because a dental prosthesis having excellent physical properties can be manufactured. When the inorganic filling rate is 72% or more, the fluidity significantly decreases, and it becomes difficult to pour it into a one-sided opening mold using a syringe or the like. However, according to the manufacturing method of this embodiment, good filling can be efficiently performed in a short time.

[0049] From the perspective that the advantages of the effects in the manufacturing method of this embodiment are significant, it is preferable that the fluidity paste P has the following viscosity. That is, the temperature of the sample stage of a rotational viscometer using parallel plates is adjusted to 30°C, 0.7 g of the sample is pressed against a φ20 mm parallel plate so that the paste thickness is 1 mm, and after standing for 1 minute, the shear rate is scanned at 1 rotation per minute, and the measured viscosity: η 1 is preferably 500 Pa·s or more.

[0050] Also, in the filling process, without using special jigs or the like, only by applying and releasing the pressure during filling, when the other opening of the bottomed mold 3 as a molding die faces upward, a part of the fluidity paste P naturally protrudes from the opening. Therefore, the dilatancy index is preferably 2 to 30, more preferably 3 to 28, and particularly preferably 4 to 25.

[0051] Here, the dilatancy index means, for a sample composed of a paste-like composition, the torque: M (Pa·m 3 ) obtained by measuring with a rotational viscometer using parallel plates with a radius of R (mm) at 30°C and a rotational speed of m (rpm). Taking M m as M m , based on this M Equation: τ m ={4M m / (3πR 3 )}×10 6 The τ m obtained by this is used as the shear stress (kPa) at the rotational speed of m (rpm). When the ratio of τ 1 to τ 10 : τ 10 / τ 1 is defined as the value. When the value of the dilatancy index exceeds 1, it means that the paste-like composition sample has dilatancy, and the larger the numerical value, the stronger the dilatancy.

[0052] The viscosity and dilatancy index of the fluid paste P can be controlled by the content of the inorganic filler (inorganic filling rate) and the composition of the inorganic filler to be blended. For example, η 1 In order for it to be 500 Pa·s or more and the dilatancy index to be 2 to 30, the inorganic filling rate should be 70% by mass or more, and spherical fine inorganic particles with an average primary particle diameter of 0.1 μm to 1 μm should be contained in an amount of 20 parts by mass or more with respect to 100 parts by mass of the total mass of the inorganic filler. The closer the particle size is to being single, the more the dilatancy tends to increase.

[0053] (3) Regarding the filling process In the filling process, a cylindrical body 3d having openings at both ends, and a flat contact surface 3a1 that contacts the fluid paste P filled in the cavity of the cylindrical body 3d. A movable bottom plate 3a as a holding member that is inserted into and retracted from the columnar cavity and forms a bottom composed of the contact surface 3a1 by staying at a predetermined position on one opening side of the cylindrical body 3d. The fluid paste P prepared in the raw material preparation process is filled into the cavity of the bottomed mold 3 having the above structure.

[0054] (3-1) Bottomed mold First, referring to FIG. 3 showing the state of the bottomed mold 3 after filling with the fluid paste P (the fluid paste P is not shown), the bottomed mold 3 will be described. The bottomed mold 3 consists of a cylindrical body 3d serving as the mold body and a movable bottom plate 3a serving as the bottom. The cylindrical body 3d has openings at both ends, that is, a closed-side opening 3b as an opening part and a supply-side opening 3c as an opening part. In the filled state, a movable bottom plate 3a having a flat contact surface 3a1 (see FIG. 7) that is slidable in the axial direction of the cylindrical body 3d is accommodated in the closed-side opening 3b with the contact surface 3a1 facing the cavity side of the cylindrical body 3d (the lower side of the drawing in FIG. 3). As also shown in FIGS. 7(B) to (D) described later, before the start of filling, the movable bottom plate 3a is arranged to block the supply-side opening 3c on the side opposite to the closed-side opening 3b (FIG. 7(B)), and as the fluid paste P is supplied and filled, it is pushed up by the fluid paste P to block the closed-side opening 3b (FIG. 7(C)). Then, when the bottomed mold 3 is inverted up and down after filling, the bottom composed of the contact surface 3a1 is formed (FIG. 7(D)). It can also be said that FIG. 3 shows only the bottomed mold 3 in the state of FIG. 7(C) extracted. In order to ensure that the movable bottom plate 3a is smoothly pushed up and the fluid paste P does not leak from the gap between the movable bottom plate 3a and the cylindrical body 3d, the shape of the movable bottom plate 3a (main surface) is preferably substantially the same as the cross-sectional shape of the cavity of the cylindrical body 3d and slightly smaller (for example, the gap between the cross-section of the movable bottom plate 3a and the cylindrical body 3d is 0.2 mm or less).

[0055] Regarding the above bottomed mold 3, for the sake of facilitating the understanding of the effects, the more detailed structure will be specifically described after explaining up to the curing process described later.

[0056] (3-2) Filling tool and filling method In the manufacturing method of the present embodiment, a filling tool 5 having a specific configuration is used in the filling process. That is, a filling plate 5c having a flat support surface 5c1 as a part of the upper surface, a filling nozzle 5e formed by an opening provided in the support surface 5c1, and a paste flow path 5c2 formed inside the filling plate 5c toward the opening of the filling nozzle 5e are used. Then, the bottomed mold 3 is placed at a predetermined position on the support surface 5c1 of the filling plate 5c, specifically, at a position where the contact surface 3a1 of the movable bottom plate 3a of the bottomed mold 3 faces the opening of the filling nozzle 5e and the support surface 5c1 around it, and after holding the cylindrical body 3d of the bottomed mold 3 so as not to move, the fluid paste P is discharged from the filling nozzle 5e and filled into the cavity of the cylindrical body 3d while pushing up the movable bottom plate 3a to a predetermined position on one end side of the cylindrical body 3d.

[0057] Hereinafter, with reference to FIGS. 4 to 6, the case of performing the filling process using the above-described filling tool 5 preferably used will be described. The filling tool 5 shown in FIG. 4 has a filling plate 5c having a flat support surface 5c1 as a part of the upper surface, and a filling nozzle 5e formed by an opening provided in the support surface 5c1. The filling nozzle 5e is connected to a paste supply device such as an injection device or an extruder (not shown) via a paste flow path 5c2 formed inside the filling plate 5c, and the fluid paste P can be supplied from the paste supply device into the cavity of the cylindrical body 3d.

[0058] Further, the filling tool 5 shown in FIG. 4 has a holding plate 5a for holding the bottomed mold 3 and a substantially U-shaped positioning block 5b for accommodating and positioning the holding plate 5a. This positioning block 5b is attached to the flat support surface 5c1 so that the bottomed mold 3 held by the holding plate 5a can be held at a predetermined position. That is, as shown in FIG. 5, by sliding the bottomed mold accommodating portion 5d holding the bottomed mold 3 on the support surface 5c1 and accommodating it in the block 5b, the filling nozzle 5e can be set at a predetermined position (for filling the fluid paste P) such that it is substantially at the center of the contact surface 3a1 of the movable bottom plate 3a. By setting it in this way, the cylindrical body 3d of the bottomed mold 3 can be held so as not to move.

[0059] Then, as shown in FIG. 6, the fluid paste P is discharged from the filling nozzle 5e, and while pushing up the movable bottom plate 3a to a predetermined position on one end side of the cylindrical body 3d, the cavity inside the cylindrical body 3d is filled with the fluid paste P.

[0060] As described above, the filling process has been described with reference to FIGS. 4 to 6. However, the manufacturing method of the present embodiment is not limited to the aspects shown in these figures, and the configuration of the filling tool 5 and the like can be appropriately changed as long as the object can be achieved. For example, in the aspect shown in the figure, the structure in which a single bottomed mold accommodating portion 5d is formed in the holding plate 5a has been described. However, a structure in which a plurality of bottomed mold accommodating portions 5d are formed in the holding plate 5a so that a plurality of bottomed molds 3 can be accommodated may also be used. Further, the shape of the positioning block 5b and the like are not limited to the U shape so that the holding plate 5a can be easily detached and fixed, and may be a V shape or a slide member such as a rail may be used. Further, the positioning block 5b may be formed as a pair of divided blocks, and the mounting position of the positioning block 5b with respect to the filling plate 5c may be changed so that the holding state of the holding plate 5a can be adjusted. Further, it is not necessary to directly fix the positioning block 5b to the filling plate 5c, and it can also be dealt with by preparing another fixing tool that can fix the position of the holding plate 5a.

[0061] Also, regarding the holding plate 5a and the bottomed form accommodating portion 5d, they can be appropriately changed to shapes and structures suitable for them in consideration of specific filling methods, positioning methods, methods of performing the previous and subsequent processes, etc. For example, it is preferable for the holding plate 5a to have a stopper mechanism that prevents it from rising beyond the height at which the movable bottom plate 3a is pushed up when a predetermined amount of the fluid paste P is filled. By having the stopper mechanism, it becomes possible to apply internal pressure to the filled fluid paste P, and in the cover process described later, the fluid paste P can be easily exposed from the supply-side opening 3c. As the stopper mechanism, for example, it is possible to adopt flange-shaped stopper pieces 5a1 and 5a2 that project from the upper ends of the side walls surrounding the periphery of the bottomed form accommodating portion 5d toward the inside of the bottomed form accommodating portion 5d in the holding plate 5a. FIG. 7 schematically shows the state when the bottomed form 3 having such a stopper piece 5a1 or 5a2 is inserted into the holding plate 5a to perform the filling process, the filled bottomed form 3 is removed from the filling tool 5, and its top and bottom are inverted. As shown in FIGS. 7(A) and 7(B), the bottomed form 3 is accommodated inside the bottomed form accommodating portion 5d by covering the holding plate 5a from above the bottomed form 3 in a state where the movable bottom plate 3a is arranged to close the supply-side opening 3c. Then, as shown in FIG. 7(C), the fluid paste P is filled from the supply-side opening 3c by an amount until the movable bottom plate 3a abuts against the stopper pieces 5a1 and 5a2 (this amount becomes the predetermined filling amount). Then, when proceeding to the cover process described later, as shown in FIG. 7(D), the holding plate 5a as a whole may be removed from the filling tool 5 and inverted top and bottom.

[0062] (4) Regarding the cover process In the covering step, first, as shown in Fig. 5, the bottomed mold 3 filled with the fluid paste P is slid on the support surface 5c1 to the area where the filling nozzle 5e does not exist and then removed from the filling tool 5. Next, the bottomed mold 3 is inverted up and down after filling. Then, as schematically shown in Fig. 7(D), the other opening (supply-side opening 3c) of the bottomed mold 3 is directed upward, and the inside of the bottomed mold 3 with the movable bottom plate 3a as the bottom plate is filled with the fluid paste P, and the fluid paste P protrudes from the supply-side opening 3c. At this time, when removing, the paste joint surface Pa of the fluid paste P temporarily exposed from the supply-side opening 3c of the bottomed mold 3 faces downward and is in a released state. However, when the filling rate of the fluid paste P is as high as, for example, 65% or more, since the viscosity is very high, even if it is in such a state for a short time, the movement of the paste in the mold does not substantially occur (even if it occurs, it does not affect the subsequent operations).

[0063] Thereafter, with a part of the fluid paste P protruding from the supply-side opening 3c, a flexible sheet as a holding member is covered from above, and the flexible sheet is brought into close contact with the paste joint surface of the fluid paste P.

[0064] If the flexible sheet is covered from above without a part of the fluid paste P protruding from the supply-side opening 3c, air is often bitten (entrained with bubbles) during covering. In that case, it becomes difficult to obtain the cut portion 1a with the desired shape, not only is a polishing process essential after the curing process, but also the polishing amount and the time required for polishing in the polishing process increase.

[0065] (4-1) Method of protruding the fluid paste P As a method of making the paste joint surface (release surface) Pa of the fluid paste P exposed from the supply-side opening 3c of the bottomed mold 3 protrude in a convex shape, since there is no need to use a special device, an internal pressure (a pressure slightly higher than atmospheric pressure) is applied to the fluid paste P in the filling process to make the fluid paste P in a slightly compressed state. In that state, it is preferable to utilize the phenomenon that the internal pressure is released by removing the bottomed mold 3 from the filling tool 5 and the fluid paste P expands slightly under atmospheric pressure. Since the paste joint surface (release surface) Pa of the fluid paste P can be made into a protruding state suitable for covering with a flexible sheet, in the filling process, as the fluid paste P, the viscosity: η 1 is 500 Pa·s or more, and the dilatancy index: τ 10 / τ 1 is 2 to 30, and it is preferable to perform filling by applying a discharge pressure of about 0.01 to 10.0 (unit: MPa) using a paste supply device such as an injection device or an extruder. The higher the viscosity, the higher the pressure tends to be due to the increase in pressure loss during filling, but it may be appropriately determined according to the paste properties and the discharge state.

[0066] Also, an elevating device that can push up the movable bottom plate 3a, which is the bottom plate of the bottomed mold 3 filled with the fluid paste P, from below may be used. For example, as shown in FIG. 8, a holding plate 6a having a through hole 6a2 into which a push-up rod 6b1 can be inserted in a retractable manner inside, and a push-up plate 6b having a push-up rod 6b1 standing upright and moving up and down in the vertical direction by a lifting device (not shown). The bottomed mold 3 filled with the fluid paste P is placed and held on the through hole 6a2 of the elevating device 6. Then, by raising the push-up plate 6b to a predetermined height and pushing up the movable bottom plate 3a by the push-up rod 6b1, the paste joint surface (release surface) Pa can be made to protrude in a convex shape according to the rising height.

[0067] The protruding state suitable for coating means that, with reference to the position of the contact surface 3a1 of the movable bottom plate 3a, the protruding height h obtained by subtracting the height of the supply-side opening 3c of the bottomed mold 3 from the height of the highest point of the paste joint surface (release surface) Pa is 0.3 to 3 mm, particularly 0.5 to 2 mm.

[0068] (4-2) Flexible Sheet and Coating Method As the flexible sheet to be placed on the convex paste joint surface (release surface) Pa of the fluid paste P from above, for example, in a sheet cut out in a rectangular shape with a main surface shape of 150 mm in length and 10 mm in width, when both sides are held at the same height in the air and the interval is narrowed in the range of 10 mm to 5 mm and then returned, it has flexibility (softness) such that it bends and flexes downward and then returns to its original state. As long as the main surface is smooth and has heat resistance equal to or higher than the polymerization temperature in the curing process, the material and the like are not particularly limited. For example, resin sheets such as PP (polypropylene), polyesters such as PET (polyethylene terephthalate), PVE (polyvinyl chloride), polyimide, polyurethane, cellophane, nylon, HDPE (high-density polyethylene), LDPE (low-density polyethylene), sheets laminated with metal foil thereon, rubber sheets such as silicone rubber and fluorine rubber can be used. From the viewpoints of handleability and heat durability, those made of PP, polyimide, PET, or polyester can be particularly preferably used. The thickness of the sheet is not particularly limited as long as it has flexibility (softness), but it is preferably in the range of 0.015 mm to 0.2 mm because it is difficult to form creases and is easy to handle.

[0069] As a method of covering the convex paste joint surface (release surface) Pa with a flexible sheet from above, as shown in Fig. 9, a flexible sheet 4 having a main surface with a shape and area that can cover the supply-side opening 3c of the bottomed mold 3 with a margin is used. Then, with the flexible sheet 4 bent convexly downward, it is slowly lowered from above until the lowest point thereof contacts the apex of the convex paste joint surface Pa of the fluid paste P filled in the bottomed mold 3 placed on the horizontal base FBa. And after contact, it is preferable to eliminate the bending so that the contact area gradually spreads around and cover it. By taking such a method, the covering can be performed without biting air (entrapping bubbles). After the covering is completed, a pressing plate FBb having a smooth surface is placed on the back surface (the surface that does not contact the fluid paste P) 4a of the flexible sheet 4 and pressed to closely adhere the sheet and the paste-like thermosetting composition and smooth the covered surface of the fluid paste P. At this time, the protruding fluid paste P overflows and adheres to the outside of the bottomed mold 3, but the amount is extremely small, and even if the curing process is performed as it is, it can be easily separated from the mold and the cured body in the mold.

[0070] For the reason that good covering is easily performed by the method described above, the flexible sheet preferably has a "bending width" determined as follows, which is an index of its flexibility, of 3 to 50 mm, more preferably 5 to 45 mm.

[0071] Method for determining the "bending width": Hold up the short sides at both ends of a rectangular sample sheet with a long side of 150 mm and a short side of 10 mm, hold it in the air so that both short sides and the periphery thereof (a region with a width of about 5 mm) are in close contact, and let the sample sheet bend naturally without bending (folding) so that the long side forms a so-called teardrop shape (the shape of a falling water droplet) in the longitudinal cross-sectional shape when viewed from one long side. In such a state, measure the maximum width (mm) of the longitudinal cross-sectional shape of the teardrop shape, and use that value as the "bending width". It can be said that the smaller the "bending width", the greater the flexibility.

[0072] In Fig. 9, the bottomed mold 3 is placed on the horizontal base FBa in a state of being removed from the holding plate 5a. However, it is of course possible to perform the covering process with the bottomed mold 3 placed while being held by the holding plate 5a.

[0073] Also, in the description of the above covering process, the paste joint surface (release surface) Pa of the fluid paste P in the bottomed mold 3 is formed in a convexly protruding state. However, if the fluid paste P and the flexible sheet can be sufficiently adhered to each other, it is not necessarily necessary to protrude the paste joint surface Pa.

[0074] (5) Regarding the curing process In the curing process, the fluid paste P filled in the bottomed mold 3 and having its paste joint surface Pa covered with the flexible sheet 4 is cured. The curing method is a so-called heat and pressure polymerization that is performed by heating at a predetermined temperature for a predetermined time according to the type of thermal polymerization initiator compounded in the fluid paste P. From the viewpoint of gently reducing the degree of polymerization shrinkage of the fluid paste P and suppressing the generation of the gap S as much as possible, the temperature is preferably 50°C to 120°C and the pressure is preferably 0.4 to 1.0 MPa during the polymerization curing. At this time, the entire bottomed mold 3 covered with the flexible sheet 4 (which may be in a state of being held by the holding plate 5a) may be placed in a container capable of applying a predetermined pressure and pressurized.

[0075] After the curing is completed, the cured body of the fluid paste P is taken out from the mold unit, and post-treatments such as removing burrs, polishing for smoothing the surface, sizing, printing, and heat treatment are performed as necessary, whereby the machined portion 1a (made of a single-layer structure HR) of the dental processing blank 1 is manufactured.

[0076] Then, a dental blank 1 can be obtained by adhering a blank holding pin 2 to the machined part to be cut 1a with an adhesive or the like. The blank holding pin 2 is not particularly limited as long as it has a shape that can fix the dental blank 1 to a cutting machine, and may not be provided depending on the shape of the dental blank 1 and the requirements of the machine. Stainless steel, brass, aluminum, etc. are used as the material of the blank holding pin 2. The method of fixing the blank holding pin 2 to the resin material for dental cutting is not limited to adhesion, and methods such as fitting and screwing can be used. There is also no particular limitation on the above adhesion method, and various commercially available adhesives such as isocyanate-based, epoxy-based, urethane-based, silicone-based, and acrylic-based can be used.

[0077] As described above, the manufacturing method of the present embodiment has been described with reference to the drawings. However, the bottomed mold 3, the filling tool 5, etc. are not limited to those shown in the drawings, and the material, shape, etc. can be appropriately changed as long as the purpose can be achieved. Also, for the covering process and the curing process, it is also possible to process a plurality of bottomed molds 3 filled with the fluid paste P together. For example, in the covering process, the bottomed molds 3 filled with the fluid paste P are arranged in a row, covered with a single flexible sheet 4, and a plurality of sets can be cured simultaneously with this as one set.

[0078] (6) Detailed structure of the bottomed mold Regarding the (3-1) bottomed mold 3 used in the above (3) filling process, in order to clarify the structure of the bottomed mold 3 as a molding die used in the present embodiment, it will be described below with reference to the drawings.

[0079] The bottomed mold 3 in Fig. 3 shows the state after filling with the fluid paste P (however, the fluid paste P is not shown in the figure). That is, the movable bottom plate 3a as a movable plate is located at the upper end of the cylindrical body 3d, and the fluid paste P is filled below the movable bottom plate 3a. Fig. 10(A) is a cross-sectional view seen from the direction of arrow A of a cross-section obtained by cutting the bottomed mold 3 in Fig. 3 with a plane B parallel to the short-side surface of the cylindrical body 3d and reversing the top and bottom. In Fig. 3, only the state of filling the bottomed mold 3 with the fluid paste P is shown, but Fig. 10(A) shows the state after covering the upper surface of the bottomed mold 3 with the flexible sheet 4 as a sheet-like member and pressing it with a pressing plate FBb (not shown) having a smooth surface to bring the flexible sheet 4 into close contact with the fluid paste P in the subsequent cover process described above.

[0080] As shown in Fig. 10(A), the bottomed mold 3 as a holding member includes a cylindrical body 3d filled with the fluid paste P, a movable bottom plate 3a located at the lower end of the cylindrical body 3d and in close contact with the fluid paste P, and a flexible sheet 4 located at the upper end of the cylindrical body 3d and in close contact with the fluid paste P. The flexible sheet 4 is preferably, for example, a PET sheet or a PP sheet.

[0081] In this state, when the curing process is performed as described above to heat and pressurize the bottomed mold 3, the fluid paste P polymerizes and shrinks with the start of polymerization, and as shown by the arrow in Fig. 10(B), a shrinkage force acts and its volume decreases. At this time, the movable bottom plate 3a provided at the lower end of the bottomed mold 3 follows the fluid paste P that shrinks as the volume decreases and slides upward inside the cylindrical body 3d (Fig. 10(C)). Thereby, the movable bottom plate 3a is maintained in a state of remaining in close contact with the fluid paste P. Further, the flexible sheet 4 provided at the upper end of the bottomed mold 3 has a portion in close contact with the fluid paste P other than the outer peripheral portion entering the inside of the cylindrical body 3d following the fluid paste P that shrinks as the volume decreases (Fig. 10(C)). Thereby, the flexible sheet 4 is maintained in a state of remaining in close contact with the fluid paste P.

[0082] Here, when polymerization shrinkage occurs, the fluid paste P inside the cylindrical body 3d shrinks toward the center (FIG. 10(B)). However, since the cylindrical body 3d has a certain degree of rigidity, unlike the movable bottom plate 3a and the flexible sheet 4, it may be difficult to follow the fluid paste P. On the other hand, depending on the sliding amount of the movable bottom plate 3a and the deformation amount of the flexible sheet 4, it is also conceivable that no gap S is generated between the cylindrical body 3d and the fluid paste P. If a gap S is generated between the cylindrical body 3d and the fluid paste P, air may enter the fluid paste P due to the residual air in the gap S, resulting in polymerization inhibition, and roughness may occur on the surface of the dental blank 1, which is the finished product. Due to the characteristic that the fluid paste P polymerizes and shrinks toward its center, it is important to prepare for the generation of a gap S between the cylindrical body 3d and the fluid paste P.

[0083] (6-1) Structure 1 FIG. 11 is a cross-sectional view showing an example of the bottomed mold 3 in the present embodiment. The bottomed mold 3 includes a cylindrical body 3d having a supply-side opening 3c as an opening at the upper end and a closing-side opening 3b as an opening at the lower end, and a movable bottom plate 3a provided at the lower end of the cylindrical body 3d for holding the fluid paste P inside the cylindrical body 3d.

[0084] In the present embodiment, the thickness of the cylindrical body 3d is formed thinner than that in FIG. 10(A). Specifically, the thickness of the cylindrical body 3d is set to a thickness that can be deformed while being in close contact with the fluid paste P as the fluid paste P filled inside the cylindrical body 3d polymerizes and shrinks. Thereby, it is possible to suppress the generation of a gap S between the fluid paste P and the cylindrical body 3d due to polymerization shrinkage.

[0085] Since the cylindrical body 3d needs to be made of a material that can deform to such an extent as to follow the polymerization shrinkage of the fluid paste P during heat and pressure polymerization, suitable materials include general-purpose resins such as PP (polypropylene), PE (polyethylene), PET (polyethylene terephthalate), PS (polystyrene), and synthetic resins such as ABS resin and PMMA resin. That is, the thermoplastic resin used for the cylindrical body 3d preferably conforms to JIS K7206 and has a Vicat softening temperature measured under a load of 5 kgf / cm2 of 70 to 110 °C. More preferably, it is 85 to 100 °C. On the other hand, the minimum thickness of the side wall of the cylindrical body 3d is preferably 0.5 to 2.0 mm, more preferably 0.7 to 1.5 mm, and even more preferably 0.9 to 1.2 mm.

[0086] As described above, the cylindrical body 3d needs to allow a certain degree of deformation. The "deformation" here refers to the plastic deformation of the cylindrical body 3d in a direction perpendicular to the central axis direction of the cylindrical body 3d, having flexibility rather than elasticity. This is because if the cylindrical body 3d deforms along the central axis direction, the overall shape of the dental processing blank 1, which is the finished product, will be deformed. Therefore, PET, PP, etc. are suitable, and materials that mainly deform with elasticity, such as silicone rubber, are not suitable.

[0087] As described above, since the bottomed mold 3 shown in FIG. 11 follows the polymerization shrinkage of the fluid paste P on the six outer surfaces of the bottomed mold 3, a gap S is less likely to occur between the bottomed mold 3 and the fluid paste P. However, since it is necessary to hold the fluid paste P in a columnar shape, it is important to prepare for the possibility that the rigidity may decrease depending on the thickness of the cylindrical body 3d and it may be easily deformed by an external force.

[0088] (6-2) Structure 2 FIG. 12(A) is a cross-sectional view showing an example of the bottomed mold 3 in the present embodiment. FIG. 12(B) is a cross-sectional view showing a modified example of the reinforcing portion 7 in FIG. 12(A). FIG. 12(C) is a cross-sectional view showing a modified example of the reinforcing portion 7 in FIG. 12(A). The bottomed mold 3 includes a cylindrical body 3d having a supply-side opening 3c at the upper end and a closed-side opening 3b at the lower end, and a movable bottom plate 3a provided at the lower end of the cylindrical body 3d and holding the fluid paste P inside the cylindrical body 3d. Further, the cylindrical body 3d has reinforcing portions 7 with increased strength at the upper end and the lower end compared to other regions.

[0089] The reinforcing portion 7 at the upper end of the cylindrical body 3d is a thick portion 8 formed so that the outer diameter increases toward the upper end in a direction perpendicular to the central axis of the cylindrical body 3d from the vicinity of the upper end of the cylindrical body 3d. That is, the thick portion 8 at the upper end has a cross-section shown in FIG. 12(A), and when viewed from one side of the central axis of the cylindrical body 3d, it has a right-angled triangular shape with the inner side at the upper end being a right angle. The vertical side of this right-angled triangular portion is flush with the region other than the thick portion 8 of the cylindrical body 3d and holds the fluid paste P. The horizontal side of the right-angled triangular portion is in close contact with the flexible sheet 4. Similarly, the reinforcing portion 7 at the lower end of the cylindrical body 3d is a thick portion 8 formed so that the outer diameter increases toward the lower end in a direction perpendicular to the central axis of the cylindrical body 3d from the vicinity of the lower end of the cylindrical body 3d. That is, the thick portion 8 at the lower end has a cross-section shown in FIG. 12(A), and when viewed from one side of the central axis of the cylindrical body 3d, it has a right-angled triangular shape with the inner side at the lower end being a right angle. The vertical side of this right-angled triangular portion is flush with the region other than the thick portion 8 of the cylindrical body 3d and holds the fluid paste P and the movable bottom plate 3a. The horizontal side of the right-angled triangular portion is placed on the horizontal table used in the curing process.

[0090] By adopting these structures, even if polymerization shrinkage occurs in the fluid paste P filled in the bottomed mold 3, the thickness of the cylindrical body 3d is kept thin in the regions other than the vicinity of the upper end and the lower end of the cylindrical body 3d, so it deforms following the shrinkage of the fluid paste P. Therefore, the adhesion between the cylindrical body 3d and the fluid paste P can be maintained, and it is possible to suppress the occurrence of roughness on the surface of the dental processing blank 1, which is the finished product, due to the formation of a gap S between the cylindrical body 3d and the fluid paste P.

[0091] Note that the structure of the reinforcing portion 7 is not limited to the above-described structure. For example, the reinforcing structure in the region indicated by circle B in FIG. 12(A) may be replaced with the structure shown in FIG. 12(B). In this case, not only the upper end but also the lower end of the cylindrical body 3d may be replaced in the same manner. In the reinforcing structure shown in FIG. 12(B), an L-shaped member 8A is provided at the upper end of the cylindrical body 3d so as to connect the outer surface of the cylindrical body 3d and the lower surface of the flexible sheet 4. The vertical portion of the L-shaped member 8A abuts on the cylindrical body 3d and contributes to holding the fluid paste P, and the horizontal portion is in close contact with the flexible sheet 4. Further, when the lower end of the cylindrical body 3d is replaced, an L-shaped member 8A is provided at the lower end of the cylindrical body 3d so as to abut on the upper surface of the horizontal base FBa on which the bottomed form 3 is placed and which is connected to the outer surface of the cylindrical body 3d. The vertical portion of the L-shaped member 8A abuts on the cylindrical body 3d and contributes to holding the fluid paste P, and the horizontal portion stabilizes the cylindrical body 3d on the upper surface of the horizontal base FBa.

[0092] Also, the reinforcing structure in the region indicated by circle B in FIG. 12(A) may be replaced with the structure shown in FIG. 12(C). In this case, not only the upper end but also the lower end of the cylindrical body 3d may be replaced in the same manner. In the reinforcing structure shown in FIG. 12(C), an angular member 8b is attached to the upper end of the cylindrical body 3d so as to connect the outer surface of the cylindrical body 3d and the lower surface of the flexible sheet 4. The angular member 8b has a structure in which a large portion that does not connect to either the outer surface of the cylindrical body 3d or the lower surface of the flexible sheet 4 is recessed, and it is possible to achieve both high strength and weight reduction. The vertical portion of the angular member 8b contacts the cylindrical body 3d and contributes to holding the fluid paste P, and the horizontal portion is in close contact with the flexible sheet 4. Further, when the angular member 8b is attached to the lower end of the cylindrical body 3d, the angular member 8b is provided at the lower end of the cylindrical body 3d so as to abut on the upper surface of the horizontal base FBa on which the bottomed form 3 is placed and which is connected to the outer surface of the cylindrical body 3d. The vertical portion of the angular member 8b abuts on the cylindrical body 3d and contributes to holding the fluid paste P, and the horizontal portion stabilizes the cylindrical body 3d on the upper surface of the horizontal base FBa.

[0093] (6-2) Structure 3 FIG. 13 is a cross-sectional view showing an example of the bottomed formwork 3 in the present embodiment. The bottomed formwork 3 has a supply-side opening 3c at the upper end and a closed-side opening 3b at the lower end, and has a first cylindrical portion 9a having thick portions 8 with increased thickness at the upper end and the lower end compared to other regions, a movable bottom plate 3a provided at the lower end of the first cylindrical portion 9a and holding the fluid paste P inside the first cylindrical portion 9a, and a second cylindrical portion 9b provided on the outer periphery of the first cylindrical portion 9a and connected to the upper end and the lower end of the first cylindrical portion 9a and having a greater thickness than the first cylindrical portion 9a.

[0094] The structure of the first cylindrical portion 9a is the same as that of the cylindrical body 3d having the reinforcing portion 7 described in the above-mentioned (6-2) structure 2 (FIG. 12(A)). In the present embodiment, the cylindrical body 3d is referred to as the first cylindrical portion 9a. On the outer peripheral side of the first cylindrical portion 9a, there is a second cylindrical portion 9b that is connected only at the upper end and the lower end of the first cylindrical portion 9a and has a greater thickness than the first cylindrical portion 9a. That is, in the present embodiment, the strength is increased by the amount of the second cylindrical portion 9b provided compared to the above-mentioned (6-2) structure 2. The thickness of the second cylindrical portion 9b only needs to be greater than that of the first cylindrical portion 9a, and may be set to a thickness that balances the vertical strength of the bottomed formwork 3 and the weight of the bottomed formwork 3. The upper end of the second cylindrical portion 9b is in close contact with the flexible sheet 4, and the lower end is placed on the horizontal plane of the curing process. That is, since the vertical strength of the bottomed formwork 3 is maintained by the second cylindrical portion 9b, the first cylindrical portion 9a can be made thinner than the cylindrical body of the above-mentioned (6-2) structure 2. The thickness only needs to be ensured to the extent that the fluid paste P filled in the first cylindrical portion 9a can be held in the internal state until it is cured.

[0095] By adopting these structures, since the second cylindrical portion 9b only needs to ensure the vertical strength of the bottomed formwork 3, the first cylindrical portion 9a can be made thinner, and even if polymerization shrinkage occurs in the fluid paste P filled in the bottomed formwork 3, it can deform following the shrinkage of the fluid paste P. Therefore, the adhesion between the cylindrical body 3d and the fluid paste P can be maintained, and it is possible to suppress the occurrence of roughness on the surface of the dental processing blank 1, which is the finished product, due to the formation of a gap S between the cylindrical body 3d and the fluid paste P.

[0096] 3. Manufacturing method of this embodiment (two-layer and multi-layer) In the above embodiments, the method for manufacturing the dental processing blank 1 having the machined portion 1a made of a single-layer hybrid resin has been described. However, the bottomed mold 3 of this embodiment can also be applied to the method for manufacturing the dental processing blank 1 having the machined portion 1a made of a two-layer or multi-layer hybrid resin with three or more layers. Hereinafter, the method for manufacturing the dental processing blank 1 with a two-layer and multi-layer structure will be described. However, the parts overlapping with the method for manufacturing the dental processing blank 1 with a single-layer structure will be omitted from the description as appropriate.

[0097] (Two-layer structure) First, a method for manufacturing the dental processing blank 1 having the machined portion 1a made of a two-layer hybrid resin will be mainly described with reference to FIG. 14. The manufacturing method includes a raw material preparation step, a bottomed mold preparation step, and a filling step.

[0098] In the raw material preparation step, a first fluid paste P1 and a second fluid paste P2 having different compositions from each other and having thermopolymerization curability, which are raw materials of the hybrid resin forming each layer of the machined portion 1a, and containing a polymerizable monomer, an inorganic filler, and a thermal polymerization initiator, are prepared.

[0099] In the bottomed mold preparation step, a cylindrical body 3d that can be divided into two cylindrical body units 3d1 and a bottomed mold 3 in which a pair of holding members are both the movable bottom plates 3a are prepared. The cylindrical body 3d is divided into two cylindrical body units 3d1, and a first bottomed mold 31 as a first molding unit and a second bottomed mold 32 as a second molding unit in which one movable bottom plate 3a is inserted into the supply-side opening 3c of each cylindrical body unit 3d1 are prepared.

[0100] In the filling process, a filling tool 5 is used, which includes a filling plate 5c having a flat support surface 5c1 on the upper surface, an opening as a filling nozzle 5e provided on the support surface 5c1, and a paste flow path 5c2 formed inside the filling plate 5c and guiding the fluid paste P toward the opening. The first bottomed mold 31 is filled with the first fluid paste P1, and the second bottomed mold 32 is filled with the second fluid paste P2 (Fig. 6).

[0101] Furthermore, the first bottomed mold 31 and the second bottomed mold 32 are placed at positions where the movable bottom plate 3a faces at least the support surface 5c1 including the opening of the filling tool 5, and after being held so that the first bottomed mold 31 and the second bottomed mold 32 do not move, the first fluid paste P1 and the second fluid paste P2 are respectively discharged from the filling nozzle 5e and the movable bottom plate 3a is slid while being pushed upward toward the other end.

[0102] Thereby, the first bottomed mold 31 is filled with the first fluid paste P1, the second bottomed mold 32 is filled with the second fluid paste P2, and a paste joint surface Pa that is planar or convex-curved outward of the cylindrical body 3d is formed on the first fluid paste P1 and the second fluid paste P2.

[0103] The manufacturing method further includes a lamination process and a curing process.

[0104] In the lamination process, the first bottomed mold 31 and the second bottomed mold 32 having the paste joint surface Pa obtained in the filling process are laminated so that the central axes coincide, and the fluid pastes P are brought into close contact with each other by overlapping the paste joint surfaces Pa with each other, thereby forming a laminate of the fluid paste P. As a result, the inside of the bottomed mold 3 formed of the cylindrical body 3d whose both ends are closed by a pair of support members composed of a pair of movable bottom plates 3a is filled with the laminate P3.

[0105] In the curing process, the laminate P3 of the fluid paste P filled in the bottomed mold 3 obtained by the lamination process is cured.

[0106] In the above lamination process, more specifically, as shown in FIG. 14, a bottomed mold 3 filled with a fluid paste P is placed and held, and the push-up plate 6b is raised to a predetermined height, and the movable bottom plate 3a is pushed up by the push-up rod 6b1, so that the paste joint surface (release surface) Pa protrudes in a convex shape according to the rising height. Then, similarly, a bottomed mold 3 filled with the fluid paste P is prepared. At this time, when the paste joint surface of one bottomed mold 3 protrudes in a convex shape, it is not necessary to form the paste joint surface of the other bottomed mold 3 in a convex shape. This is because the reason for protruding the paste joint surface of one bottomed mold 3 is to apply an internal pressure (a pressure slightly higher than the atmospheric pressure) to the fluid paste P in one bottomed mold 3 to put the fluid paste P in a slightly compressed state, and to release the internal pressure by removing it from the filling tool 5, and to utilize the phenomenon that the fluid paste P expands slightly under the atmospheric pressure. However, the paste joint surface of the other bottomed mold 3 may be formed in a convex shape.

[0107] Thereafter, one of the two bottomed molds 3 filled with the fluid paste P is turned upside down, and the paste joint surfaces are overlapped and adhered to each other so that the central axes of the bottomed molds 3 coincide. As a result, a laminate P3 of the fluid paste P in which the two bottomed molds 3 are laminated is formed, and when this is cured in the curing process, two dental processing blanks 1 are integrally formed. By laminating these two bottomed molds 3, the cylindrical bodies 3d are also laminated. At this time, since the two bottomed molds 3 are laminated, two cylindrical bodies 3d are laminated. In this way, when two cylindrical bodies 3d are laminated, each cylindrical body 3d is referred to as a cylindrical body unit 3d1. That is, the cylindrical body 3d can be divided in the axial direction of the cylindrical body 3d into two cylindrical body units 3d1 that form the cylindrical body 3d.

[0108] Here, when curing the bottomed mold 3, the fluid paste P undergoes polymerization shrinkage in the same manner as when manufacturing the dental blank 1 with a single-layer structure. When the fluid paste P undergoes polymerization shrinkage, since the paste joint surfaces are overlapped and adhered to each other as described above, the masses of the two fluid pastes P polymerize and shrink integrally. At this time, similar to the dental blank 1 with a single-layer structure, a gap S is generated between the bottomed mold 3 and the fluid paste P due to polymerization shrinkage, which may cause air intrusion into the fluid paste P and polymerization inhibition of the fluid paste P by residual air, and roughness may occur on the surface of the completed dental blank 1. In addition, since the two layers of the fluid paste P are adhered, displacement may occur due to differences in shrinkage rates or the like on the boundary line where the paste joint surfaces contact each other, and roughness may occur on the surface of the completed dental blank 1. Therefore, it is important to prepare for the occurrence of a gap S between the cylindrical body 3d and the fluid paste P.

[0109] Thus, even when manufacturing the dental blank 1 with a two-layer structure, by using the bottomed mold 3 having the features shown in FIGS. 11 to 13 of the present embodiment in the same manner as in the case of the single-layer structure described above, it is possible to suppress the generation of a gap S between the bottomed mold 3 and the fluid paste P and the occurrence of roughness on the surface of the completed dental blank 1.

[0110] (Multi-layer structure) Next, a method for manufacturing a dental blank 1 having a machinable portion 1a made of a hybrid resin with a multi-layer structure having n layers, where n is an integer of 3 or more, will be mainly described with reference to FIG. 15. The manufacturing method includes a raw material preparation step, a bottomed mold preparation step, and a filling step.

[0111] In the raw material preparation step, n types of fluid pastes P corresponding to n layers, which are different in composition from each other and have thermopolymerization curability, including polymerizable monomers, inorganic fillers, and thermal polymerization initiators, which are raw materials of the hybrid resin forming each layer of the machinable portion 1a, are prepared.

[0112] In the bottomed mold preparation process, a cylindrical body 3d that can be divided into n cylindrical body units 3d1 corresponding to n layers, and a bottomed mold 3 in which a pair of holding members are both movable bottom plates 3a are prepared, and the n cylindrical body units 3d1 are numbered and divided. Specifically, when the cylindrical body 3d is formed by connecting, starting from one end of the cylindrical body 3d towards the other end, the cylindrical body unit 3d1 located at one end becomes the first cylindrical body 3d1, and the cylindrical body unit 3d1 located at the other end becomes the nth cylindrical body 3dn.

[0113] Prepare n bottomed molds 3 consisting of the first bottomed mold 31 to the nth bottomed mold 31n as the nth molding die units, with one movable bottom plate 3a inserted into the opening at one end of each of the divided cylindrical body units 3d1.

[0114] In the filling process, as shown in FIG. 6, using a filling tool 5 having a filling plate 5c with a flat support surface 5c1 on the upper surface, an opening as a filling nozzle 5e provided on the support surface 5c1, and a paste flow path 5c2 formed inside the filling plate 5c and guiding the fluid paste P towards the opening, one of the n types of fluid pastes P with different types is filled into the interiors of the n bottomed molds respectively.

[0115] Furthermore, place each of the n bottomed molds 3 at a position where the movable bottom plate 3a faces at least the support surface 5c1 including the opening of the filling tool 5, and hold each bottomed mold 3 so that it does not move. Then, discharge the fluid paste P to be filled from the filling nozzle 5e respectively, and slide while pushing up the movable bottom plate 3a towards the other end, and fill each fluid paste P into the interior of each bottomed mold 3. Thereby, a paste joint surface Pa that is planar or convex curved outward of the cylindrical body 3d is formed for each fluid paste P.

[0116] The above manufacturing method further includes an initial lamination process, an intermediate lamination process, and a curing process.

[0117] In the initial lamination process, the first bottomed mold 31 and the second bottomed mold 32 each having a paste joint surface Pa are laminated so that their central axes coincide, and the paste joint surfaces Pa are overlapped with each other to bring the fluid pastes P into close contact with each other, thereby forming a laminate P3 of the fluid pastes P. Further, the laminate P3 is filled inside a connector C of a first cylindrical body unit 3d11 and a second cylindrical body unit 3d12 whose both ends are closed by a pair of support members each consisting of a pair of movable bottom plates 3a. Thereafter, only the movable bottom plate 3a of the second cylindrical body unit 3d12 is removed to form a paste joint surface Pa of the fluid paste P in a planar shape or a convex curved surface shape outward of the connector.

[0118] In the intermediate lamination process, the connector C having the paste joint surface Pa formed thereon and the third bottomed mold 33 as a third molding die unit having a connection surface Ca formed thereon are laminated so that their central axes coincide, and the paste joint surfaces Pa are overlapped with each other to bring the fluid pastes P into close contact with each other, thereby forming a laminate P3 of the fluid pastes P composed of three layers. Further, the laminate P3 is filled inside a connector of a first cylindrical body 3d1 to a third cylindrical body 3d3 whose both ends are closed by a pair of support members each consisting of a pair of movable bottom plates 3a. Thereafter, only the movable bottom plate 3a of the third bottomed mold is removed to form a paste joint surface Pa of the fluid paste P in a planar shape or a convex curved surface shape outward of the connector. Then, these operations are repeated until a connector C in which a laminate P3 of the fluid pastes P composed of (n - 1) layers is filled and the connector C having the paste joint surface Pa formed thereon is obtained in the connector C of the first bottomed mold 31 to the (n - 1)th bottomed mold 31n1 as the (n - 1)th molding die unit.

[0119] In the final lamination process, the connector C of the first bottomed mold 31 to the (n - 1)th bottomed mold 31n1 and the nth bottomed mold 31n are laminated so that their central axes coincide, and the paste joint surfaces Pa are overlapped with each other to bring the fluid pastes P into close contact with each other, thereby forming a laminate of the fluid paste Pn composed of n layers. Further, the laminate is filled inside a bottomed mold 3 composed of a cylindrical body 3d whose both ends are closed by a pair of support members each consisting of a pair of movable bottom plates 3a.

[0120] In the curing process, the laminate of the fluid paste P filled in the bottomed mold 3 obtained by the final lamination process is cured.

[0121] Here, when curing the bottomed mold 3, the fluid paste P undergoes polymerization shrinkage in the same manner as when manufacturing the single-layer dental blank 1. When the fluid paste P undergoes polymerization shrinkage, since the paste joint surfaces are overlapped and adhered as described above, the masses of n fluid pastes P polymerize and shrink integrally. At this time, similar to the single-layer dental blank 1, a gap S is generated between the bottomed mold 3 and the fluid paste P due to polymerization shrinkage, which may cause air intrusion into the fluid paste P and inhibition of polymerization of the fluid paste P by residual air, and roughness may occur on the surface of the completed dental blank 1. In addition, since the n layers of fluid paste P are adhered, displacement may occur due to differences in shrinkage rates or the like on the boundary line where the paste joint surfaces contact each other, and roughness may occur on the surface of the completed dental blank 1. Therefore, it is important to prepare for the generation of a gap S between the cylindrical body 3d and the fluid paste P.

[0122] Thus, even when manufacturing the multi-layer dental blank 1, by using the bottomed mold 3 having the features shown in FIGS. 11 to 13 of the present embodiment in the same manner as in the case of the single-layer structure described above, it is possible to suppress the generation of a gap S between the bottomed mold 3 and the fluid paste P and roughness on the surface of the completed dental blank 1.

[0123] [Effect] According to the above embodiments, the following effects are achieved.

[0124] (1) The bottomed mold 3 of the dental processing blank 1 includes a cylindrical body 3d having a closed-side opening 3b and a supply-side opening 3c at one end and the other end respectively, and a holding member that holds the fluid paste P having thermopolymerizable curability filled inside the cylindrical body 3d by closing the closed-side opening 3b and the supply-side opening 3c of the cylindrical body 3d. The cylindrical body 3d is dividable in the axial direction of the cylindrical body 3d into one or more cylindrical body units 3d1 that form the cylindrical body 3d, and the thickness of the cylindrical body 3d is set to a thickness that deforms while remaining in close contact with the fluid paste P as the fluid paste P filled inside the cylindrical body 3d polymerizes and shrinks.

[0125] As a result, when the volume of the fluid paste P filled in the cylindrical body 3d decreases due to polymerization shrinkage, the cylindrical body 3d deforms following while remaining in close contact with the fluid paste P, so that it is possible to suppress the occurrence of a gap S between the cylindrical body 3d and the fluid paste P. Therefore, it is possible to suppress the occurrence of air intrusion into the fluid paste P and polymerization inhibition due to the residual air in the gap S, and the occurrence of roughness on the surface of the dental processing blank 1.

[0126] In addition, in order to obtain the dental processing blank 1 as a finished product, additional operations such as grinding and polishing for surface smoothing are not required. Therefore, the time required for the additional operations can be shortened, and the material loss can be reduced.

[0127] (2) In the bottomed mold 3, the cylindrical body 3d is made of a thermoplastic resin that conforms to JIS K7206 and has a Vicat softening temperature measured under a load of 5 kgf / cm 2 in the range of 70 to 110 °C, and the minimum thickness of the cylindrical body 3d is 0.5 to 1.5 mm.

[0128] Accordingly, a thermoplastic resin with high followability to the fluid paste P is selected in the temperature range during the heat and pressure polymerization of the fluid paste P filled in the cylindrical body 3d. Further, the thickness of the cylindrical body 3d can be optimized so as to achieve both followability to the fluid paste P and rigidity of the cylindrical body 3d. Therefore, when the volume of the fluid paste P decreases due to polymerization shrinkage, the followability of the cylindrical body 3d to the fluid paste P can be improved, so that the generation of a gap S between the cylindrical body 3d and the fluid paste P can be suppressed.

[0129] (3) In the bottomed mold 3, the cylindrical body 3d has a reinforcing portion 7 that keeps the distance between one end and the other end constant.

[0130] Thereby, the rigidity in the direction connecting one end and the other end of the cylindrical body 3d can be improved. Therefore, while reducing the thickness of the cylindrical body 3d to improve the followability to the fluid paste P, the rigidity of the entire bottomed mold 3 can be maintained, so that in particular, deformation of the fluid paste P due to deformation of the cylindrical body 3d can be suppressed.

[0131] (4) In the bottomed mold 3, the cylindrical body 3d has thick portions 8 with increased thickness at one end and the other end compared to other regions.

[0132] Thereby, the rigidity of the cylindrical body 3d can be improved in the portions of the cylindrical body 3d where the movable bottom plate 3a is provided and the portion where the flexible sheet 4 is provided. Therefore, the thickness can be reduced in other regions of the cylindrical body 3d, so that the followability of the cylindrical body 3d to the fluid paste P can be improved and the generation of a gap S between the cylindrical body 3d and the fluid paste P can be suppressed.

[0133] (5) In the bottomed mold 3, the cylindrical body 3d has a double structure including a first cylindrical portion 9a having the thick portion 8 and a second cylindrical portion 9b connected only at one end and the other end of the first cylindrical portion 9a from the outer peripheral side of the first cylindrical portion 9a.

[0134] As a result, since the rigidity in the direction connecting one end and the other end of the cylindrical body can be covered by the second cylindrical portion 9b, the first cylindrical portion 9a can have a thinner thickness within a range where it can hold the fluid paste P before curing filled in the cylindrical body 3d. Therefore, the followability of the cylindrical body 3d to the fluid paste P can be improved, and the occurrence of a gap S between the cylindrical body 3d and the fluid paste P can be suppressed.

[0135] (6) At least one of the pair of holding members is a movable bottom plate 3a that is inserted into the opening at the other end and slides into the inside of the cylindrical body 3d while remaining in close contact with the fluid paste P as the fluid paste P polymerizes and shrinks.

[0136] As a result, at least one of the pair of holding members is the movable bottom plate 3a, and the movable bottom plate 3a can slide inside the cylindrical body 3d while remaining in close contact with the fluid paste P in the cylindrical body 3d. Therefore, the close contact state with the fluid paste P can be maintained regardless of the degree of polymerization shrinkage. Thus, the followability of the cylindrical body 3d to the fluid paste P can be improved, and the occurrence of a gap S between the cylindrical body 3d and the fluid paste P can be suppressed.

[0137] (7) The bottomed mold 3 of the dental processing blank 1 according to claim 1 having a pair of holding members, wherein one of the pair of holding members is a movable bottom plate 3a that is inserted into the opening at the other end and can slide into the inside of the cylindrical body 3d while remaining in close contact with the fluid paste P as the fluid paste P polymerizes and shrinks, and the other is a flexible sheet 4 that can be deformed while remaining in close contact with the fluid paste P exposed at the opening at one end. As a result, the flexible sheet 4 is adopted as the other of the pair of holding members, and the flexible sheet 4 can be deformed to follow the fluid paste P even when the fluid paste P in close contact at the opening polymerizes and shrinks. Therefore, the occurrence of a gap S between the cylindrical body 3d and the fluid paste P can be suppressed.

[0138] A method for manufacturing a dental blank 1 having a machined portion 1a composed of a hybrid resin includes a raw material preparation step of preparing a fluid paste P having thermopolymerization curability, which contains a polymerizable monomer, an inorganic filler, and a thermal polymerization initiator, as raw materials of the hybrid resin; a filling tool 5 having a filling plate 5c having a flat support surface 5c1 on the upper surface, an opening as a filling nozzle 5e provided on the support surface 5c1, and a paste flow path 5c2 formed inside the filling plate 5c and guiding the fluid paste P toward the opening. Using the filling tool 5, the bottomed mold 3 according to claim 7 in which the flexible sheet 4 is not attached and the movable bottom plate 3a is inserted so as to close the supply-side opening 3c of the cylindrical body 3d is placed at a position where the movable bottom plate 3a faces at least the support surface 5c1 including the opening of the filling tool 5 and held so that the bottomed mold 3 does not move. Then, the fluid paste P is discharged from the filling nozzle 5e and the movable bottom plate 3a is slid while being pushed upward toward the other end to fill the inside of the bottomed mold 3 with the fluid paste P in a filling step; the bottomed mold 3 filled with the fluid paste P is slid on the support surface 5c1 to a region that does not overlap with the opening and then removed from the filling tool 5. The supply-side opening 3c of the cylindrical body 3d is directed upward, and the flexible sheet 4 is placed so as to be in close contact with the fluid paste P at the supply-side opening 3c, and a covering step of bringing the paste joint surface between the flexible sheet 4 and the fluid paste P into close contact; and a curing step of curing the fluid paste P filled in the bottomed mold 3.

[0139] Thereby, when manufacturing the dental blank 1 composed of a single-layer hybrid resin, since the cylindrical body 3d of the bottomed mold 3 deforms following while remaining in close contact with the fluid paste P, it is possible to suppress the generation of a gap S between the cylindrical body 3d and the fluid paste P. Therefore, it is possible to suppress the occurrence of air intrusion into the fluid paste P and polymerization inhibition due to the residual air in the gap S, and to suppress the occurrence of roughness on the surface of the dental blank 1.

[0140] (9)A method for manufacturing a dental processing blank having a machined portion composed of a two-layer hybrid resin includes a raw material preparation step of preparing a first flowable paste P1 and a second flowable paste P2 having different compositions from each other and having thermopolymerization curability, which are raw materials of the hybrid resin forming each layer of the machined portion 1a, and containing a polymerizable monomer, an inorganic filler, and a thermal polymerization initiator; a bottomed mold preparation step of preparing a bottomed mold 3 as claimed in claim 6, which can be divided into two cylindrical body units 3d1, and preparing a first bottomed mold 31 and a second bottomed mold 32, in which the cylindrical body 3d is divided into two cylindrical body units 3d1, and one movable bottom plate 3a is respectively inserted into the supply-side openings 3c of each cylindrical body unit 3d1; a filling step of using a filling tool 5 having a filling plate 5c having a flat support surface 5c1 on the upper surface, an opening as a filling nozzle 5e provided on the support surface 5c1, and a paste flow path 5c2 formed inside the filling plate 5c and guiding the flowable paste P toward the opening, filling the inside of the first bottomed mold 31 with the first flowable paste P1 and filling the inside of the second bottomed mold 32 with the second flowable paste P2. In the filling step, the first bottomed mold 31 and the second bottomed mold 32 are placed at positions where the movable bottom plate 3a faces at least the support surface 5c1 including the opening of the filling tool 5, and after being held so that the first bottomed mold 31 and the second bottomed mold 32 do not move, the first flowable paste P1 and the second flowable paste P2 are respectively discharged from the filling nozzle 5e and slid while pushing up the movable bottom plate 3a toward the other end, filling the first bottomed mold 31 with the first flowable paste P1 and filling the second bottomed mold 32 with the second flowable paste P2, and forming a paste joint surface Pa that is planar or convex-curved outward of the cylindrical body 3d on the first flowable paste P1 and the second flowable paste P2. The manufacturing method includes laminating the first bottomed mold and the second bottomed mold having the paste joint surface Pa so that the central axes coincide, and bringing the paste joint surfaces Pa into contact with each other to adhere the first flowable paste and the second flowable paste, forming a laminate of the flowable paste P, and a laminating step of filling the inside of the bottomed mold 3 composed of the cylindrical body 3d whose both ends are closed by a pair of support members composed of a pair of movable bottom plates 3a with the laminate; the laminate obtained by the laminating step,It further includes a curing step of curing a laminate of the fluid paste P filled in the bottomed mold 3.

[0141] Accordingly, even when manufacturing the dental processing blank 1 composed of the hybrid resin having a two-layer structure, similar to the single-layer structure, the cylindrical body 3d of the bottomed mold 3 deforms following while remaining in close contact with the fluid paste P, so that it is possible to suppress the generation of a gap S between the cylindrical body 3d and the fluid paste P. Further, even when a shift occurs due to a difference in shrinkage rate at a portion where the fluid pastes P having different compositions are in close contact with each other, the cylindrical body 3d deforms following, so that it is possible to suppress the generation of a gap S between the fluid paste P and the cylindrical body 3d. Therefore, it is possible to suppress the occurrence of air intrusion into the fluid paste P and polymerization inhibition due to the residual air in the gap S, and to suppress the occurrence of roughness on the surface of the dental processing blank 1.

[0142] A method for manufacturing a dental blank 1 having a machined portion 1a composed of a hybrid resin with a multilayer structure having n layers which are integers of 3 or more includes a raw material preparation step of preparing n types of fluid pastes P corresponding to the n layers, which are thermally polymerizable and have different compositions from each other, and contain a polymerizable monomer, an inorganic filler, and a thermal polymerization initiator, which are raw materials of the hybrid resin for forming each layer of the machined portion 1a; a bottomed mold preparation step of preparing a bottomed mold 3 according to claim 6, in which a cylindrical body 3d that can be divided into n cylindrical body units 3d1 corresponding to the n layers, and a pair of holding members are both movable bottom plates 3a, and numbering and dividing the n cylindrical body units 3d1 so that when the n cylindrical body units 3d1 are connected to form the cylindrical body 3d, the cylindrical body unit 3d1 located at one end becomes the first cylindrical body and the cylindrical body unit 3d1 located at the other end becomes the nth cylindrical body as going from one end of the cylindrical body 3d to the other end, and preparing n bottomed molds 3 composed of a first bottomed mold 31 to an nth bottomed mold, in which one movable bottom plate 3a is inserted into the opening at one end of each of the divided cylindrical body units 3d1; a filling step of using a filling tool 5 having a filling plate 5c having a flat support surface 5c1 on the upper surface, an opening as a filling nozzle 5e provided on the support surface 5c1, and a paste flow path 5c2 formed inside the filling plate 5c and guiding the fluid paste P toward the opening, and filling the inside of the n bottomed molds 3 with one type each of the n types of fluid pastes P having different types from each other. In the filling step, after placing the n bottomed molds 3 at positions where the movable bottom plates 3a face at least the support surface 5c1 including the opening of the filling tool 5 and holding the n bottomed molds 3 so as not to move, the fluid pastes P to be filled are respectively discharged from the filling nozzles 5e and the movable bottom plates 3a are slid while being pushed upward toward the other end, and each of the fluid pastes P is filled into the inside of each bottomed mold 3 to form a paste joint surface Pa that is planar or convex curved surface-shaped outward of the cylindrical body 3d. The manufacturing method includes laminating the first bottomed mold 31 and the second bottomed mold 32 having the paste joint surface Pa so that the central axes coincide, and bringing the paste joint surfaces Pa into contact with each other to closely adhere the fluid pastes P to each other.While forming a laminate of the fluid paste P and filling the inside of a connected body of a first cylindrical body unit and a second cylindrical body unit, both ends of which are closed by a pair of support members each consisting of a pair of movable bottom plates 3a, with the laminate, only the movable bottom plate of the second cylindrical body unit is removed to form a paste joint surface Pa of the fluid paste in a planar shape or a convex curved surface shape outward of the connected body. This is the first lamination step. Then, the connected body with the joint surface formed and the third bottomed mold with the joint surface formed are laminated so that their central axes coincide, and the fluid pastes are brought into close contact with each other by overlapping the paste joint surfaces Pa with each other, thereby forming a laminate of the fluid paste consisting of three layers and filling the inside of a connected body of the first to third cylindrical bodies, both ends of which are closed by a pair of support members each consisting of a pair of movable bottom plates 3a, with the laminate. Subsequently, only the movable bottom plate 3a of the third bottomed mold is removed to form a paste joint surface Pa of the fluid paste P in a planar shape or a convex curved surface shape outward of the connected body. This operation is repeated in the intermediate lamination step until a connected body filled with a laminate of the fluid paste P consisting of (n - 1) layers and having the paste joint surface Pa formed therein is obtained. In the final lamination step, the connected body of the first to (n - 1) bottomed molds 31 to the (n - 1)th bottomed mold and the nth bottomed mold are laminated so that their central axes coincide, and the fluid pastes P are brought into close contact with each other by overlapping the paste joint surfaces Pa with each other, thereby forming a laminate of the fluid paste P consisting of n layers and filling the inside of a bottomed mold 3 consisting of a cylindrical body 3d, both ends of which are closed by a pair of support members each consisting of a pair of movable bottom plates 3a, with the laminate. Further included is a curing step of curing the laminate of the fluid paste P filled in the bottomed mold 3 obtained by the final lamination step.

[0143] Thus, even when manufacturing the dental blank 1 composed of a hybrid resin with a multilayer structure, similar to the single-layer structure, the cylindrical body 3d of the bottomed mold 3 follows and deforms while remaining in close contact with the fluid paste P, so that the generation of a gap S between the cylindrical body 3d and the fluid paste P can be suppressed. Further, even when a shift occurs due to a difference in shrinkage rate at a portion where the fluid pastes P having different compositions are in close contact with each other, the cylindrical body 3d follows and deforms, thereby suppressing the generation of a gap S between the fluid paste P and the cylindrical body 3d. Therefore, it is possible to suppress the intrusion of air into the fluid paste P and polymerization inhibition caused by the residual air in the gap S, and suppress the occurrence of roughness on the surface of the dental blank 1.

Example

[0144] Hereinafter, the present embodiment will be described more specifically by way of examples, but the present embodiment is not limited to these examples.

[0145] The compounds used as raw materials for the paste-like polymerizable curable composition and their abbreviations are shown below. ·UDMA: 1,6-bis(methacryloylethyloxycarbonylamino)trimethylhexane ·TEGDMA: triethylene glycol dimethacrylate ·BPO: benzoyl peroxide.

[0146] [Polymerizable monomer mixture] As the polymerizable monomer mixture, it was mixed and used as follows. ·UDMA: 70 parts by mass, TEGDMA: 30 parts by mass, and BPO: 1.0 part by mass.

[0147] [Inorganic filler] As the inorganic filler, the following was used. · Spherical silica zirconia having an average particle size of 0.2 μm and a refractive index of 1.54 (surface-treated with γ-methacryloyloxypropyltrimethoxysilane).

[0148] [Flexible sheet] As the flexible sheet, the following was used. · A sheet made of polypropylene with a thickness of 0.1 mm and a "flexure width" of 30 mm measured by the method described in item (4-2).

[0149] [Pressing plate] · A PP plate-shaped body with a width of 12 mm, a depth of 18 mm, and a thickness of 1 mm.

[0150] Example 1 (1) Raw material preparation step The polymerizable monomer mixture and the inorganic filler were mixed using a planetary mixer until uniform so that the blending amount of the inorganic filler with respect to 100 parts by mass of the polymerizable monomer was 230 parts by mass, and then defoamed under vacuum to prepare a fluid paste P (paste 1) with a filling rate of 70% by mass.

[0151] Viscosity of the prepared fluid paste-based composition: η 1 And when the dilatancy index was measured by the following method, η 1 was 621 Pa·s and the dilatancy index was 19.0.

[0152] <Viscosity measurement> Using a Modular Compact Rheometer MCR302 (manufactured by Anton Paar), a rotational viscometer using parallel plates, the viscosity η 1 (unit: Pa·s) measured under the conditions of temperature: 30°C and rotational speed: 1 rpm was measured. That is, first, an aluminum disposable sample stage was installed on the apparatus main body, and the temperature of the sample stage was adjusted to 30°C. After the temperature of the sample stage became stable, 0.7 g of the paste-like polymerizable and curable composition as the sample was taken on the sample stage and pressed with a parallel plate (φ20 mm, R = 10 mm) connected to the apparatus main body so that the thickness of the paste became 1 mm. After standing in this state for 1 minute, using the measurement software RheoCompass (manufactured by Anton Paar), the shear rate was scanned at 1 rotation per minute to obtain the paste viscosity η 1 (Pa·s) of the thermally polymerizable and curable composition.

[0153] <Measurement of dilatancy index> In the same manner as above, after pressing the sample with a parallel plate (φ20 mm, R = 10 mm) and allowing it to stand for 1 minute, using the measurement software RheoCompass (manufactured by Anton Paar), the shear rate was scanned at 1 rotation per minute and 10 rotations per minute, and the torque measured at 1 rpm: M 1 (unit: Pa·m 3 ) and the torque measured at 10 rpm (unit: Pa·m 3 ): M 10 From the following formula (III) τ m ={4M m / (3πR 3 )}×10 6 ···(III) According to this, the corresponding shear stress (unit: kPa) τ 1 and τ 10 were respectively obtained, and based on the obtained values, the dilatancy index defined by τ 10 / τ 1 was determined.

[0154] (2) Filling process Next, using the cylindrical body 3d made of PP shown in Fig. 3, specifically, having a rectangular shape with an internal cavity having a height of 16.0 mm, a length of 12.0 mm, and a width of 18.0 mm at both ends and a minimum wall thickness of 1.2 mm, and a bottomed mold 3 having a movable bottom plate 3a made of PP with a length of 11.8 mm, a width of 17.8 mm, and a thickness of 2.0 mm (the height of the cavity filled with the fluid paste P is 16.0 mm), and a filling tool 5 having the same structure as shown in Fig. 4 (however, the holding plate 5a used was the one having the stopper piece 5a1 shown in Fig. 7), the paste 1 extruded by an extruder was supplied from the filling nozzle 5e into the inside of the bottomed mold 3 and filled until the movable bottom plate 3a abutted against the stopper piece 5a1.

[0155] (3) Covering process and curing process After that, as shown in Fig. 5, after sliding the bottomed mold 3 to separate it from the filling tool 5 and then turning it upside down, the paste release surface protruded with a protrusion height h; 1 mm.

[0156] Place the bottomed mold 3 with a protruding paste release surface on a horizontal table. As shown in Fig. 9, cover the paste release surface with a PP sheet with a thickness of 0.1 mm from above, and then place a "pressing plate" on the upper surface of the sheet to make the sheet and the paste adhere closely. As a result, no air bubbles were observed. After heating and curing the bottomed mold 3 (filled with paste 1) with the pressing plate placed thereon at 100 °C for 2 hours, a cured body that becomes the cut portion 1a made of a single-layer structure HR was obtained by extracting it from the cured body type.

[0157] (4) Evaluation of the cured body Similarly, 20 cured bodies were produced, and for the 20 obtained cured bodies, the presence or absence of surface roughness due to air intrusion and polymerization inhibition was evaluated. Those with remaining surface roughness were judged as unqualified, and the yield rate of the 20 cured bodies was determined. As a result, the yield rate was 100%.

[0158] Examples 2 to 3 In Example 1, except that the ratio of the polymerizable monomer composition and the inorganic filler used in the raw material preparation step was changed as shown in Table 1 to prepare the fluid paste P of each No., a cured body was created and evaluated in the same manner as in Example 1.

[0159]

Table 1

[0160]

Table 2

[0161]

Table 3

[0162] Examples 16 to 22 Except for changing the bottomed mold 3 used to those with the No. shown in Table 3 and further changing the heating temperature in the curing process to the temperature shown in Table 4, a cured body was created and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

[0163] The evaluation results of Examples 1 to 22 are shown in Table 4. For Examples 1 to 5, the yield rate was 100% in all cases. For Examples 6 to 15, the yield rate was high regardless of the No. of the bottomed mold 3 used. In particular, when the bottomed mold 3 with the minimum side wall thickness of the cylindrical body 3d being 0.9 to 1.2 mm was used, and when the bottomed mold 3 with the Vicat softening temperature of the resin material being 85 to 100 °C was used, the yield rate was 100%. For Examples 14 to 20, the yield rate was high regardless of any bottomed mold 3 and heating temperature. In particular, when cured at a heating temperature corresponding to the Vicat softening temperature of the resin material of the bottomed mold 3, the yield rate was 100%.

[0164] [Table 4]

[0165] Comparative Examples 1 to 8 Except for changing the bottomed mold 3 to be used to those with No. 14 to 19 shown in Table 5, a cured body was created and evaluated in the same manner as in Example 1. Also, for the resin materials, PA (polyacetylene) and POM (polyoxymethylene) used for the bottomed mold 3 No. 18, 19 in Table 5, in accordance with JIS K7206, 5 kgf / cm 2 The Vicat softening temperature (B50 method) measured under the load is shown in Table 6.

[0166] [Table 5]

[0167] [Table 6]

[0168] The evaluation results of Comparative Examples 1 to 8 are shown in Table 7. For Comparative Examples 1 and 2, since the minimum wall thickness of the cylindrical body 3d is smaller than the claimed range and the side wall of the cylindrical body 3d is likely to be deformed by pressure, a gap S is likely to occur, and thus the yield rate is clearly reduced. For Comparative Examples 3 and 4, since the minimum wall thickness of the cylindrical body 3d is larger than the claimed range and the side wall of the cylindrical body 3d is too thick to follow the polymerization shrinkage of the fluid paste P, the yield rate is reduced. For Comparative Examples 5 and 6, when the Vicat softening temperature of the resin material of the bottomed mold 3 is higher than 110°C, the side wall of the cylindrical body 3d fails to follow the polymerization shrinkage of the fluid paste P during curing, and thus the yield rate is reduced. For Comparative Examples 7 and 8, when curing is performed at a heating temperature lower than the Vicat softening temperature of the resin material of the bottomed mold 3, the side wall of the cylindrical body 3d fails to follow the polymerization shrinkage of the fluid paste P during curing, and thus the yield rate is reduced.

[0169]

Table 7

[0170] Each of the above-described embodiments shows a preferred specific example of the present invention. The numerical values, components, arrangement positions of the components, order of connection forms, etc. shown in the above embodiments are merely examples and are not intended to limit the present invention. Also, each figure is not necessarily drawn precisely.

[0171] As described above, the embodiments of the present invention have been explained. However, the above embodiments merely show a part of the application examples of the present invention and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

Explanation of Reference Numerals

[0172] 1 Dental processing blank 1a Cut portion 3 Bottomed mold (molding die) 31 First bottomed mold (first molding die unit) 32 Second bottomed mold (second molding unit) 33 Third bottomed mold (third molding unit) 31n1 (n - 1)th bottomed mold ((n - 1)th molding unit) 31n nth bottomed mold (nth molding unit) 3a Movable bottom plate (holding member, movable plate) 3b Closing side opening (opening) 3c Feeding side opening (opening) 3d Cylindrical body 3d1 First cylindrical body 3d3 Third cylindrical body 3dn nth cylindrical body 3d1 Cylindrical body unit 3d11 First cylindrical body unit 3d12 Second cylindrical body unit 3d1n nth cylindrical body unit 4 Flexible sheet (holding member, sheet - like member) 5 Filler 5c Filling tray 5c1 Support surface 5c2 Paste flow path 5e Filling nozzle 6b Pushing plate 6b1 Pushing rod 7 Reinforcing part 8 Thick part 8a L - shaped member 8b Angular member 9a First cylindrical part 9b Second cylindrical part C Connector Ca Connecting surface P Flowable paste P1 First flowable paste P2 Second flowable paste P3 Laminate Pa Paste joint surface

Claims

1. A cylindrical body having openings at one end and the other end respectively, A pair of holding members for holding a fluid paste having thermopolymerizable curability filled inside the cylindrical body by closing the openings at the one end and the other end of the cylindrical body, A mold comprising: The cylindrical body is divisible in the axial direction of the cylindrical body into one or more cylindrical body units forming the cylindrical body, The thickness of the cylindrical body is set to a thickness that deforms while remaining in close contact with the fluid paste as the fluid paste filled inside the cylindrical body polymerizes and shrinks. A mold for dental blanks, characterized by the above.

2. A mold for dental blanks according to Claim 1, The cylindrical body complies with JIS K7206 and is composed of a thermoplastic resin having a Vicat softening temperature measured at a load of 5 kgf / cm ２ of 70 to 110°C, and the minimum thickness of the cylindrical body is 0.5 to 1.5 mm A mold for dental blanks, characterized by the above.

3. A mold for dental blanks according to Claim 1, The cylindrical body has a reinforcing portion that keeps the distance between the one end and the other end constant. A mold for dental blanks, characterized by the above.

4. A mold for dental blanks according to Claim 3, The cylindrical body has thickened portions with increased thickness at the one end and the other end compared to other regions. A mold for dental blanks, characterized by the above.

5. A mold for dental blanks according to Claim 4, The cylindrical body has a double structure including a first cylindrical portion having the thickened portion and a second cylindrical portion connected only at the one end and the other end of the first cylindrical portion from the outer peripheral side of the first cylindrical portion. A mold for dental blanks, characterized by the above.

6. A mold for dental blanks according to Claim 1, At least one of the pair of holding members is a movable plate that is inserted into the opening at the other end and is slidable inside the cylindrical body while remaining in close contact with the fluid paste as the fluid paste polymerizes and shrinks. A mold for dental blanks, characterized by the above.

7. A mold for dental blanks according to Claim 1 having the pair of holding members, One of the pair of holding members is a movable plate that is inserted into the opening at the other end and is slidable inside the cylindrical body while remaining in close contact with the fluid paste as the fluid paste polymerizes and shrinks, and the other is a sheet-like member that is deformable while remaining in close contact with the fluid paste exposed at the opening at the one end. A mold for dental blanks, characterized by the above.

8. A method for manufacturing a dental blank having a machined portion composed of a hybrid resin, a raw material preparation step of preparing the fluid paste having thermopolymerization curability, which contains a polymerizable monomer, an inorganic filler, and a thermal polymerization initiator, as a raw material of the hybrid resin; using a filling tool having a filling plate having a flat support surface on the upper surface, an opening as a filling nozzle provided on the support surface, and a paste flow path formed inside the filling plate and guiding the fluid paste toward the opening, the mold according to claim 7 in which the sheet-like member is not attached and the movable plate is inserted so as to close the opening at the one end of the cylindrical body, placing the movable plate at a position facing at least the support surface including the opening of the filling tool, holding the mold so as not to move, and then discharging the fluid paste from the filling nozzle and sliding the movable plate while pushing it upward toward the other end to fill the inside of the mold with the fluid paste; a filling step; a covering step of sliding the mold filled with the fluid paste on the support surface to a region not overlapping with the opening and then removing it from the filling tool, turning the opening at the one end of the cylindrical body upward, covering the sheet-like member so as to be in close contact with the fluid paste at the opening at the one end, and bringing the paste joint surface between the sheet-like member and the fluid paste into close contact; a curing step of curing the fluid paste filled in the mold; A method for manufacturing a dental blank, characterized by including the steps.

9. A method for manufacturing a dental blank having a machined portion composed of a hybrid resin having a two-layer structure, a raw material preparation step of preparing a first fluid paste and a second fluid paste having different compositions from each other and having thermopolymerization curability, which contain a polymerizable monomer, an inorganic filler, and a thermal polymerization initiator, as raw materials of the hybrid resin for forming each layer of the machined portion; a mold unit preparation step of preparing a cylindrical body that can be divided into two cylindrical body units and a mold according to claim 6 in which both of the pair of holding members are the movable plate, dividing the cylindrical body into two cylindrical body units, and preparing a first mold unit and a second mold unit in which one movable plate is inserted into the opening at the one end of each cylindrical body unit; A filling tool having a filling plate with a flat support surface on top, an opening as a filling nozzle provided on the support surface, and a paste flow path formed inside the filling plate and guiding the fluid paste toward the opening is used. A filling step of filling the first fluid paste inside the first mold unit and filling the second fluid paste inside the second mold unit is included, In the filling step, the first mold unit and the second mold unit are placed at a position where the movable plate faces at least the support surface including the opening of the filling tool, and after holding the first mold unit and the second mold unit so as not to move, the first fluid paste and the second fluid paste are respectively discharged from the filling nozzle and slid while pushing up the movable plate toward the other end, filling the first mold unit with the first fluid paste and filling the second mold unit with the second fluid paste, and forming a paste joint surface that is planar or convex curved outward of the cylindrical body on the first fluid paste and the second fluid paste. The manufacturing method is a laminating step of laminating the first mold unit and the second mold unit having the paste joint surface obtained by the filling step so that the central axes coincide, and bringing the paste joint surfaces into contact with each other to bring the first fluid paste and the second fluid paste into close contact with each other, forming a laminate of the fluid paste, and filling the inside of the mold composed of the cylindrical body whose both ends are closed by the pair of support members composed of the pair of movable plates with the laminate, a curing step of curing the laminate of the fluid paste filled in the mold obtained by the laminating step is further included, A method for manufacturing a dental blank having a machined portion composed of a two-layer hybrid resin, characterized in that.

10. A method for manufacturing a dental blank having a machined portion composed of a multilayer hybrid resin having n layers which are integers of 3 or more, a raw material preparation step of preparing n types of fluid pastes corresponding to the n layers, which are different in composition from each other and have thermopolymerization curability, including a polymerizable monomer, an inorganic filler, and a thermal polymerization initiator, which are raw materials of the hybrid resin forming each layer of the machined portion Prepare the mold according to claim 6, wherein the cylindrical body that can be divided into n cylindrical body units corresponding to the n layers, and a pair of holding members are both the movable plates. When the n cylindrical body units are connected to form the cylindrical body, number and divide them such that when moving from one end to the other end of the cylindrical body, the cylindrical body unit located at one end becomes the first cylindrical body unit, and the cylindrical body unit located at the other end becomes the nth cylindrical body unit. Prepare n molding die units consisting of a first molding die unit to an nth molding die unit, with one of the movable plates inserted into the opening at one end of each of the divided cylindrical body units. This is the molding die unit preparation step. Using a filling tool having a filling plate with a flat support surface on the upper surface, an opening as a filling nozzle provided on the support surface, and a paste flow path formed inside the filling plate and guiding the fluid paste toward the opening, fill the inside of the n molding die units with one type each of the n types of fluid pastes having different types from each other. This is the filling step. including In the filling step, place the n molding die units at positions where the movable plates face at least the support surface including the opening of the filling tool, hold the molding die units so that they do not move, and then discharge the fluid paste to be filled from the filling nozzle and slide the movable plates upward toward the other end while pushing them, filling the inside of each molding die unit with each fluid paste to form a paste joint surface that is planar or convex curved outward from the cylindrical body. The manufacturing method is Stack the first molding die unit and the second molding die unit having the paste joint surface obtained in the filling step so that the central axes coincide, and bring the paste joint surfaces into contact with each other to closely adhere the fluid pastes to each other, forming a laminate of the fluid pastes. After filling the inside of the connected body of the first cylindrical body unit and the second cylindrical body unit, the both ends of which are closed by the pair of support members composed of the pair of movable plates, with the laminate, remove only the movable plate of the second cylindrical body unit to form a paste joint surface that is planar or convex curved outward from the connected body. This is the first lamination step. Stack the connector with the paste joint surface formed and the third molding die unit with the joint surface formed so that their central axes coincide, and bring the paste joint surfaces into contact with each other to closely adhere the fluid pastes to each other, thereby forming the laminate of the fluid pastes composed of three layers and filling the inside of the connector of the first to third cylindrical bodies closed at both ends by the pair of support members composed of the pair of movable plates with the laminate. Subsequently, remove only the movable plate of the third molding die unit to form the paste joint surface that is planar or convex-curved outward from the connector. Repeat this operation until the inside of the connector of the first to (n - 1) molding die units is filled with the laminate of the fluid pastes composed of (n - 1) layers and the connector with the paste joint surface formed is obtained. This is the intermediate lamination step. Stack the connector of the first to (n - 1) molding die units and the nth molding die unit so that their central axes coincide, and bring the paste joint surfaces into contact with each other to closely adhere the fluid pastes to each other, thereby forming the laminate of the fluid pastes composed of n layers and filling the inside of the molding die composed of the cylindrical bodies closed at both ends by the pair of support members composed of the pair of movable plates with the laminate. This is the final lamination step. A curing step of curing the laminate of the fluid paste filled in the molding die obtained by the final lamination step. Further comprising A method for manufacturing a dental processing blank having a machined portion composed of a hybrid resin having a multilayer structure with n layers, where n is an integer of 3 or more.

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