Dental prosthesis and manufacturing method thereof, dental prosthesis manufacturing kit, and ceramic article manufacturing method

Abstract

To provide a zirconia prosthesis capable of easily applying an adhesion system including a combination of a pretreatment agent containing a silane coupling agent and a dental adhesion such as dental resin cement without a need to make a sandblast treatment essential to bond it to a target such as a tooth well, and usable for a long time in an environment in an oral cavity which becomes high in temperature and humidity.SOLUTION: The zirconia prosthesis in which only a surface layer part of an adhesive surface is selectively conjugated with a silicon dioxide is obtained by impregnating a front surface of a surface which becomes an adhesive surface after cutting a zirconia dental mill blank having a cut part made of, for example, a partially stabilized zirconia slightly porous calcined body by using a CAD / CAM system with a treatment liquid containing an aqueous solution or a suspension of alkali metal silicate such as sodium silicate to sinter it.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a dental prosthesis and a method for manufacturing the same, a kit for manufacturing a dental prosthesis, and a method for manufacturing a ceramic article. [Background technology]

[0002] In particular, in recent years, advances in information and communication technology (ICT) have led to the widespread adoption of computer-aided design (CAD) and computer-aided manufacturing (CAM) technologies in the dental field. For example, when fabricating dental prostheses, CAD / CAM systems are increasingly being used. These systems use intraoral images to machine dental blanks made of nonmetallic materials. Here, a dental blank refers to a workpiece (also called a mill blank) that can be attached to a milling machine in a CAD / CAM system. It typically includes a workpiece to be machined and a holder for attaching it to the milling machine. Commonly known workpieces include solid blocks shaped like rectangular parallelepipeds or cylinders, or solid disks shaped like plates or plates.

[0003] Zirconia-based ceramic materials are often used as non-metallic materials because of their excellent strength and toughness, allowing for the fabrication of aesthetic dental prostheses. Because fully sintered zirconia-based ceramic materials are difficult to machine due to their strength, when using a CAD / CAM system to fabricate dental prostheses (hereinafter referred to as "zirconia prostheses") made of zirconia-based ceramics, a zirconia-based ceramic pre-sintered body pre-sintered at a relatively low sintering temperature is generally used as the machining target for dental zirconia mill blanks (also simply referred to as "zirconia mill blanks"). Based on CAD, which takes into account shrinkage that occurs during high-temperature sintering, the blank is then machined to a shape corresponding to the final prosthesis shape obtained by CAM, and then sintered to produce a dense, high-strength zirconia prosthesis.

[0004] Regarding zirconia-based ceramics, pure zirconia (zirconium oxide) undergoes a phase transition accompanied by a volume change depending on the temperature. Therefore, stress caused by the volume change during the cooling process after sintering can cause cracks and lead to a decrease in strength. To prevent this phase transition, stabilizers such as yttrium oxide, calcium oxide, and magnesium oxide have been added to stabilize zirconia or partially stabilized zirconia, which can exist as a tetragonal or mixed crystal system of tetragonal and cubic crystals stable at high temperatures without transitioning to a monoclinic crystal stable at low temperatures even upon cooling. Such stabilized zirconia or partially stabilized zirconia is also used as the zirconia raw material powder used in zirconia mill blanks, and alumina (an additive) is commonly added to further increase strength. For example, Patent Document 1 describes a raw material powder that can be pressure-sintered to produce a zirconia sintered body that is particularly suited to anterior dentures and has both translucency and strength, and that contains "4.0 mol % to 6.5 mol % of yttria and less than 0.1 wt % of alumina, and has a BET specific surface area of ​​8 to 15 m. 2 / g」。

[0005] Zirconia prostheses, including those made of stabilized zirconia or partially stabilized zirconia, are generally treated with a pretreatment agent containing a silane coupling agent and then bonded using a dental adhesive, such as a dental resin cement, that contains a component that reacts with the silane coupling agent (e.g., a silica component or a polymerizable monomer) or a component with high affinity (an organic component). However, because the amount of Zr-O-Si bonds formed by the silane coupling agent, which contribute to improving adhesive strength, is small, sandblasting (to increase the number of surface Zr-OH groups) is required to achieve practical adhesive strength (see Non-Patent Document 1).

[0006] In addition, a method has been proposed in which, instead of a pretreatment agent containing a silane coupling agent, a dental adhesive composition containing a phosphonic acid group-containing (meth)acrylate monomer, such as an acetone solution of 6-methacryloxyhexyl-phosphonoacetate, is used (see Patent Document 2). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-143178 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-045179 [Patent Document 3] Japanese Patent Application Publication No. 02-21858 [Non-patent literature]

[0008] [Non-Patent Document 1] Kimura et al., "Development of a new primer and a new surface treatment method for zirconia dental adhesion," Journal of the Adhesion Society of Japan, 2019, Vol. 55, No. 3, pp. 10-17 Summary of the Invention [Problem to be solved by the invention]

[0009] The combination of a pretreatment agent containing a silane coupling agent and a dental adhesive, such as dental resin cement, which contains a component that reacts with the silane coupling agent (e.g., a silica component or a polymerizable monomer) or a component with high affinity (an organic component) is an adhesive system that is widely used in the dental field, but there is currently no known technology for easily applying this system to effectively bond zirconia prostheses.

[0010] That is, as described in Non-Patent Document 1, in order to apply the above system to a zirconia prosthesis, prior sandblasting is required, and not only is it affected by this, but it has also been reported that the tensile bond strength of the hardened hybrid resin composition after immersion in water at 37°C for 24 hours in a sandblasted system as shown in Non-Patent Document 1 was 18.8 MPa, but that the bond strength significantly decreased when sandblasted zirconia was left in the air for several hours, and it cannot be said that it has sufficient adhesive properties.

[0011] Furthermore, the method of using a dental adhesive composition described in Patent Document 2 may be effective for specific adherends such as zirconia ceramics, but is not only inconvenient because it cannot be used with other adherend systems, but also requires that a specific photocurable composition be applied to the margin with the resin cement and then photocured when used.

[0012] Therefore, an object of the present invention is to provide a technology for effectively bonding zirconia prostheses, and in particular articles made of ceramics made of inorganic oxides that are substantially free of silicon dioxide components, by simply applying an adhesive system consisting of a combination of a pretreatment agent containing a silane coupling agent and the above-mentioned dental adhesive, such as a dental resin cement, without the need for sandblasting. [Means for solving the problem]

[0013] The present invention solves the above-mentioned problems, and a first aspect of the present invention is a composition containing zirconium oxide and at least one stabilizer selected from the group consisting of yttrium oxide, calcium oxide, magnesium oxide, cerium oxide, and erbium oxide, and is substantially free of silicon dioxide components. 「 Stabilized zirconia sintered body or partially stabilized zirconia sintered body "; and a "composite" obtained by combining the "stabilized zirconia sintered body or partially stabilized zirconia sintered body" with "silicon dioxide"; A dental prosthesis having a body consisting of: the surface of the body has an adhesive surface to be adhered to an adherend and an exposed surface exposed to the surface; When the surface layer is defined as a range of 5 to 300 μm in depth from the surface, the surface layer of the adhesive surface in is present in the surface layer 「 silicon dioxide 」 and The "stabilized zirconia sintered body or partially stabilized zirconia sintered body" and By compounding The "complex" is formed. , The portion of the main body other than the surface layer portion is made of the "stabilized zirconia sintered body or partially stabilized zirconia sintered body", The dental prosthesis (hereinafter also referred to as "the dental prosthesis of the present invention") is characterized by the above.

[0014] A second aspect of the present invention is a method for producing the dental prosthesis of the present invention, comprising: a cutting process step of cutting a zirconia dental mill blank having a cuttable portion made of a microporous calcined body of stabilized zirconia or a microporous calcined body of partially stabilized zirconia, the microporous calcined body containing zirconium oxide and at least one stabilizer selected from the group consisting of yttrium oxide, calcium oxide, and magnesium oxide, and substantially no silicon dioxide component, using a CAD / CAM system to obtain a semi-finished product made of the microporous calcined body, the semi-finished product having a shape corresponding to the shape of a desired dental prosthesis; A water-based solution of alkali metal silicate is applied to the surface of the semi-finished product corresponding to the adhesive surface. mosquito A processing solution consisting of Apply this a treatment step of infiltrating the surface to retain an alkali metal silicate on the surface; and a sintering step of sintering the semi-finished product that has undergone the above-mentioned treatment step at a temperature of 1200 to 1800°C; a method for producing the dental prosthesis, comprising:

[0015] In the manufacturing method of the above form (hereinafter also referred to as "the manufacturing method of the dental prosthesis of the present invention"), it is preferable that the microporous calcined body constituting the cutting processing portion of the zirconia dental mill blank is a microporous calcined body having a relative density of 45 to 65% and pores open to the outside, the treatment liquid is a sodium silicate aqueous solution having a sodium silicate concentration of 15 to 70 mass %, and in the treatment step, sodium silicate is retained in the surface layer portion up to a depth of 5 to 300 μm on the surface.

[0016] A third aspect of the present invention is A dental prosthesis manufacturing kit for manufacturing the dental prosthesis of the present invention by the dental prosthesis manufacturing method of the present invention, comprising: The kit for manufacturing a dental prosthesis (hereinafter also referred to as "the kit of the present invention") comprises: a zirconia dental mill blank having a cutting portion made of a microporous calcined body of stabilized zirconia or a microporous calcined body of partially stabilized zirconia, which contains zirconium oxide and at least one stabilizer selected from the group consisting of yttrium oxide, calcium oxide, and magnesium oxide, and is substantially free of silicon dioxide; and a treatment liquid made of an aqueous sodium silicate solution having a sodium silicate concentration of 15 to 70 mass %. [Effects of the Invention]

[0018] Although the dental prosthesis of the present invention is a zirconia prosthesis, it maintains the same level of aesthetics, mechanical strength, and other physical properties as conventional zirconia prostheses, and can be easily bonded to adherends such as teeth, metals, and hybrid resins with adhesive strength sufficient to withstand use in the oral environment (high temperature, high humidity) by simply applying an adhesive system consisting of a combination of a pretreatment agent containing a silane coupling agent and a dental adhesive such as a dental resin cement. Furthermore, sandblasting can be omitted during bonding, and even if sandblasting is performed, the bonding is less affected by the conditions.

[0019] Furthermore, according to the method for manufacturing a dental prosthesis of the present invention, it is possible to efficiently manufacture the dental prosthesis of the present invention having the above-mentioned excellent characteristics, for example, by using the kit of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] Although the present invention is not bound by any theory, the reason why the dental prosthesis of the present invention exhibits the above-mentioned excellent effects is believed to be as follows. Specifically, the adhesive system provides good adhesive strength because the surface layer of the adhesive surface is composited with silicon dioxide, increasing the number of surface silanol groups (Si-OH groups) on the adhesive surface. When the adhesive system is applied, these silanol groups react with a silane coupling agent, forming chemical bonds with components of dental adhesives, such as dental resin cements, via Si-O-Si bonds, improving affinity. In this case, the silicon dioxide in the surface layer penetrates into the main body in a complex manner with a predetermined thickness, firmly integrating with the main body through an anchoring effect, thereby ensuring that adhesive strength does not decrease even with long-term use in the oral cavity. Furthermore, because the composite layer is not exposed on the surface after adhesion but is limited to the very surface, it does not adversely affect aesthetics or overall mechanical strength.

[0022] Such a composite in a limited region, such as the surface layer of a specific region on the surface, can be realized by employing the method for manufacturing a dental prosthesis of the present invention. For example, when a general coating method is employed in which a silicon dioxide precursor is applied to the surface of a zirconia (present) sintered body and heat-treated at a relatively low temperature, as described in Patent Document 3, the strong integration due to the anchor effect and chemical bonding described above does not occur, and there is always a concern of a decrease in adhesive strength due to peeling, etc.

[0023] The present invention will be described in detail below. In this specification, unless otherwise specified, the expression "x to y" using numerical values ​​x and y means "greater than or equal to x and less than or equal to y." In such an expression, when a unit is assigned only to the numerical value y, the unit also applies to the numerical value x.

[0024] 1. Dental prosthesis of the present invention Dental prostheses are artificial objects used to replace missing or chipped teeth, and examples thereof include inlays, onlays, crowns, bridges, implant superstructures, denture bases, etc. During prosthetic treatment, these are used by adhering them to teeth or adherends such as metals or organic-inorganic composite materials using dental adhesives such as dental resin cement. Therefore, the main body of the dental prosthesis has an adhesive surface that is adhered to the adherend and an exposed surface that is exposed to the surface.

[0025] The main body of the dental prosthesis of the present invention is essentially a zirconia prosthesis made of a stabilized zirconia sintered body or a partially stabilized zirconia sintered body. Here, the stabilized zirconia sintered body or the partially stabilized zirconia sintered body is a sintered body of a crystalline zirconium oxide powder (raw material powder) containing a stabilizer, and the raw material powder preferably further contains aluminum oxide as an additive. However, silicon dioxide components such as silica are not typically blended. In the present invention, the stabilized zirconia sintered body or the partially stabilized zirconia sintered body constituting the adhesive surface of the main body of the dental prosthesis, excluding the surface layer, is substantially free of silicon dioxide components. "Substantially free of silicon dioxide components" means that the silicon dioxide component is not contained, or if it is contained, the silicon dioxide component content is 0.030% by mass or less, preferably 0.025% by mass or less, based on the total mass of the main body.

[0026] To explain the raw material powder in more detail, the stabilizer may be any of those conventionally used as stabilizers for zirconium oxide, such as yttrium oxide, calcium oxide, magnesium oxide, cerium oxide, and erbium oxide, without any restrictions. However, yttrium oxide is particularly preferred, and since it becomes stabilized zirconia or partially stabilized zirconia after sintering, the content of yttrium oxide is preferably 5 to 14 parts by mass per 100 parts by mass of zirconium oxide (0.027 to 0.076 mol per 1 mol of zirconium oxide).

[0027] Aluminum oxide functions as a sintering aid for zirconium oxide, and its content is preferably 0.005 to 0.3 parts by weight per 100 parts by weight of zirconium oxide. If the content of aluminum oxide is less than 0.005 part by weight, it may not be effective as a sintering aid, and if the content is more than 0.3 part by weight, the difference in refractive index with zirconium oxide may result in a decrease in translucency, making it unsuitable for dental prostheses.

[0028] The raw material powder is not particularly limited as long as it is easy to handle as a powder, but the average crystallite size is preferably 0.001 μm to 50 μm, particularly 0.003 μm to 20 μm, because phase transformation of the oxide crystal is unlikely to occur and grain growth does not proceed excessively by sintering. Examples of such raw material powder that can be used include ZpexSmile (manufactured by Tosoh Corporation), Zpex4 (manufactured by Tosoh Corporation), and Zpex (manufactured by Tosoh Corporation).

[0029] The raw material powder may contain a pigment. There are no particular limitations on the pigment, and known pigments can be used in any combination, such as erbium oxide, cobalt oxide, iron oxide, etc. Furthermore, pigments that are white before sintering but can be colored after sintering and used as a pigment can also be used.

[0030] The stabilized zirconia sintered body or partially stabilized zirconia sintered body that constitutes the main body of the dental prosthesis of the present invention means a body in which pore shrinkage and grain growth occur during the sintering process, and which ultimately has "a dense structure in which alumina grains are dispersed in a polycrystalline structure in which tetragonal zirconia grains and cubic zirconia grains, each containing a stabilizer dissolved at a different concentration, are randomly dispersed and adjacent to each other."

[0031] The dental prosthesis of the present invention is characterized in that the surface layer of the adhesive surface of the main body, specifically the surface layer extending from the surface to a depth of 5 to 300 μm, preferably 10 to 200 μm, is selectively composited with silicon dioxide. This composite in the surface layer can be confirmed by analysis using X-ray diffraction (hereinafter sometimes abbreviated as XRD) or electron probe microanalyzer (hereinafter sometimes abbreviated as EPMA). These analyses reveal the formation of an amorphous silicon dioxide phase that at least partially covers the surface of the main body, with a portion of the silicon dioxide (on the main body side) immobilized within complexly shaped pores. No alkali metal oxides are detected in the surface layer. Such a composite structure can also be understood from the method of formation (specifically, the treatment and sintering steps in the dental prosthesis of the present invention). That is, during the sintering process, alkali metals with melting points lower than the sintering temperature disappear by sublimation or other processes, forming amorphous silicon dioxide within the pores and on the surface. It is possible that some of the silicon dioxide (especially near the interface) may have formed a complex oxide with the (partially) stabilized zirconia components. Cooling after sintering then forms a silicon dioxide phase that at least partially covers the surface of the body, with some of that silicon dioxide (on the body side) immobilized within the complex-shaped pores. In this way, the silicon dioxide (with Si-OH groups) exposed on the surface of the body is firmly integrated with the body through the anchoring effect (and, in some cases, chemical bonding due to the complex oxide formation). Therefore, the silane coupling treatment effectively acts on the adhesive surface, resulting in the aforementioned effects.

[0032] 2. Manufacturing method of dental prosthesis of the present invention The method for manufacturing a dental prosthesis of the present invention is a method for manufacturing a dental prosthesis of the present invention, and is characterized by including the cutting step, the treatment step, and the sintering step. Each step will be described below.

[0033] 2-1. About the cutting process In the cutting process, a zirconia dental mill blank has a cuttable portion made of a microporous calcined body of stabilized zirconia or a microporous calcined body of partially stabilized zirconia, which contains zirconium oxide and at least one stabilizer selected from the group consisting of yttrium oxide, calcium oxide, and magnesium oxide, and is substantially free of silicon dioxide components. The cuttable portion is cut using a CAD / CAM system to obtain a semi-finished product made of the microporous calcined body, which has a shape corresponding to the shape of the desired dental prosthesis.

[0034] As described below, the above-mentioned zirconia dental mill blank is also a commonly available zirconia dental mill blank, and therefore the cutting process in the method for manufacturing a dental prosthesis of the present invention is not particularly different from the process of cutting the zirconia mill blank using a CAD / CAM system to obtain a semi-finished product (machined body) corresponding to the shape of the zirconia prosthesis (before sintering) when manufacturing a zirconia prosthesis using a conventional common zirconia mill blank. Therefore, here, we will first explain the raw materials and manufacturing methods of commonly available zirconia dental mill blanks, and then explain the cutting process.

[0035] (1) Zirconia dental mill blanks A zirconia dental mill blank refers to a mill blank having a portion to be machined and a holder for attaching the portion to a machine, wherein the portion to be machined is a microporous calcined body of stabilized zirconia or a microporous calcined body of partially stabilized zirconia that contains zirconium oxide and at least one stabilizer selected from the group consisting of yttrium oxide, calcium oxide, and magnesium oxide, and is substantially free of silicon dioxide. The portion to be machined is generally a (solid) block formed into a rectangular or cylindrical shape, or a (solid) disk formed into a plate or plate shape.

[0036] The term "calcined body" (also referred to as "preliminary sintered body") refers to a state before the material is sintered in the sintering process. During the sintering process, necks are formed where the constituent particles of the raw material powder are partially joined together, and as these necks grow, open pores (i.e., pores open to the outside) originating from the voids between the particles are formed. In the present invention, the term "microporous calcined body" refers to a body in which a large number of these open pores remain.

[0037] The microporous calcined body in the present invention is preferably a microporous calcined body having a relative density of 45 to 65% and pores that are open to the outside. The cutting portion of a commonly available zirconia dental mill blank is made of a microporous calcined body of stabilized zirconia or partially stabilized zirconia having a relative density of 45 to 65% and pores that are open to the outside, so in the present invention, a general zirconia dental mill blank having such a cutting portion can be used without any particular restrictions.

[0038] The relative density is the ratio of actual density to theoretical density (calculated as relative density = (actual density / theoretical density) × 100(%)), and can be adjusted by controlling the temperature and time of pre-sintering. Furthermore, if pre-sintering is performed to achieve this relative density, the pre-sintered body will typically be microporous, with pores open to the outside. The average pore diameter of these pores is typically within the range of 50 to 200 nm. Here, the average particle diameter refers to the median diameter determined from the pore volume distribution in the pore diameter range of 5 nm to 250 μm obtained by mercury intrusion porosimetry, i.e., measurement using a mercury porosimeter.

[0039] For example, the theoretical density of zirconium oxide varies depending on the type and content of stabilizer and the content of alumina additive, and is 6.10 g / cm, which is the theoretical density of tetragonal zirconia. 3 As the content of these elements increases, the density tends to decrease slightly. For example, Table 1 of Patent Document 1 shows the theoretical density of zirconia containing yttria and alumina, which is reproduced below for reference. The actual density can be determined by density measurement such as the Archimedes method.

[0040] [Table 1]

[0041] (2) Manufacturing method of zirconia dental mill blanks Zirconia dental mill blanks are generally produced by molding the raw material powder into a predetermined shape and then calcining it. The raw material powder may optionally contain binders, fine fillers, light-shielding agents, fluorescent agents, etc., and then calcined to produce a microporous calcined body. When a binder component is added, for example, an acrylic binder, an olefin binder, or wax may be used.

[0042] The raw material composition containing such raw material powders is molded by obtaining a compression molded body or green body of a predetermined shape using methods such as press molding, extrusion molding, injection molding, and casting. Multi-stage molding may also be used. For example, the raw material powders may be uniaxially pressed and then further subjected to CIP (Cold Isostatic Pressing). In addition, multiple types of mixed powders may be stacked and molded in the molding process. The shape of the compression molded body or green body may be determined appropriately depending on the shape of the desired mill blank, but is usually a disk-shaped body (disk type) or a rectangular or approximately rectangular parallelepiped shape (block type).

[0043] The resulting molded body can be calcined (preliminary sintered) to produce a microporous calcined body. The calcination (preliminary sintering) involves calcining (firing) the compression molded body or green body, after optionally degreasing, at a temperature lower than that for the main sintering. Here, degreasing refers to a process for volatilizing or decomposing and removing moisture, solvents, binders, and the like contained in the compression molded body or green body. Calcination refers to a process for heating metal oxide powder particles to cause molecular and atomic diffusion (adhesion and fusion) on the surface, transforming them into a polycrystalline body and improving the strength of the resulting microporous preliminarily sintered body to a level that makes it easy to handle and process. The calcination temperature is typically between 600°C and 1200°C, preferably between 800°C and 1000°C.

[0044] The degreasing and / or calcination treatment may be carried out by any conventionally known method without any particular limitations, and may be carried out continuously or in multiple stages. Furthermore, in order to efficiently remove organic substances, it is preferable to carry out the treatment in an oxygen-containing air atmosphere. The degreasing and / or calcination treatment may also be carried out continuously by a method using the same equipment as the preceding molding step, such as the SPS (Spark Plasma Sintering) method or the HP (Hot Press) method.

[0045] (3) Cutting method In the cutting process, the portion to be cut of the zirconia dental mill blank is cut using a CAD / CAM system to obtain a semi-finished product made of the microporous calcined body having a shape corresponding to the shape of the desired dental prosthesis.

[0046] A CAD / CAM system is a system that uses computer-aided design (CAD) to design desired three-dimensional shape data and then performs computer-aided manufacturing (CAM). As mentioned above, CAD is performed taking into account shrinkage that occurs during high-temperature sintering. The shape of the semi-finished product is similar to the main body, but is larger by the amount of the shrinkage (rate), so it has a surface that corresponds to the bonding surface and a surface that corresponds to the exposed surface.

[0047] Since the zirconia dental mill blank is machined while being joined via a support rod during cutting, after cutting using a CAD / CAM system, the support rod may be removed and the shape may be further modified using a dental laboratory engine or the like, or the surface may be polished. Furthermore, if necessary, the color tone may be adjusted using a penetrating colorant or a clarifying liquid, etc.

[0048] 2-2. Treatment process In the treatment step, a treatment liquid consisting of an aqueous solution or suspension of an alkali metal silicate is impregnated into the surface of the semi-finished product corresponding to the bonding surface, so that the alkali metal silicate is retained on the surface layer of the surface.

[0049] The alkali metal silicate may be one having a SiO2 / M2O (M represents an alkali metal element) molar ratio of 1.0 to 5.0, either singly or in combination. Sodium silicate and / or potassium silicate are preferred due to their water solubility and availability, and sodium silicate is particularly preferred due to its sintering temperature and melting point. The SiO2 / M2O molar ratio is preferably 2.0 to 4.0.

[0050] The treatment liquid may be a suspension or colloidal dispersion of fine particles of an alkali metal silicate in a dispersion medium, preferably water, but is preferably an aqueous solution from the viewpoint of penetrability into the micropores of the semi-finished product. When the treatment liquid is an aqueous solution, the concentration of the alkali metal silicate is preferably 15 to 70 mass %, particularly 25 to 60 mass %, from the viewpoint of penetrability of the treatment liquid. When the treatment liquid is an aqueous sodium silicate solution, various concentrations of water glass are commercially available, so a solution of an appropriate concentration can be used as is, or a high concentration solution can be diluted and used.

[0051] When applying the treatment liquid to the adhesive surface of the main body, general application methods, such as application with a coating brush or paintbrush, or spraying, can be used without any particular restrictions. The amount of application is 1 cm per 1 cm of the application surface. 2 The amount of alkali metal silicate per unit mass is 0.001 to 0.07 g / cm2 in terms of silicon dioxide. 2 , especially 0.003 to 0.06 g / cm 2 It is preferable to set the density to 0.005 to 0.05 g / cm 2 By applying such an amount, the treatment solution can be permeated to a depth from the surface layer in the range of 5 to 300 μm, preferably 10 to 200 μm.

[0052] After the treatment step is completed and before proceeding to the sintering step, it is preferable to carry out a drying treatment to remove the dispersion medium and solvent. The drying treatment can be carried out, for example, by leaving it at atmospheric pressure and room temperature.

[0053] 3-3. About the sintering process The sintering process in the method for producing a dental prosthesis of the present invention is not particularly different from the conventional process of sintering a semi-finished product (machined body) when producing a zirconia prosthesis using a general zirconia mill blank, except that the semi-finished product (machined body) to be sintered has undergone the above-mentioned treatment process, and the semi-finished product is sintered at a temperature of 1200 to 1800° C. If the sintering temperature is less than 1200° C., the structure may not be sufficiently densified, and if the sintering temperature is more than 1800° C., the silicon dioxide may disappear. The sintering temperature is preferably 1250 to 1750°C, more preferably 1300 to 1700°C, because this is expected to result in densification of the zirconia structure and efficient compounding of zirconia and silicon dioxide. Sintering is typically carried out in the atmosphere using a furnace such as a dental firing furnace. The sintering time varies depending on the sintering temperature, but is typically about 10 minutes to 6 hours, preferably about 30 minutes to 4 hours. For example, a good sintered body can be obtained by sintering for 2 hours at 1450°C. In this way, the dental prosthesis of the present invention, which has the excellent adhesiveness described above, can be obtained.

[0054] 4. Kit of the Present Invention When manufacturing the dental prosthesis of the present invention by the manufacturing method of the dental prosthesis of the present invention, it is preferable to use a kit including the zirconia dental mill blank and the treatment liquid so that the cutting process and the treatment process can be carried out smoothly.

[0055] 5. Method for using (bonding) the dental prosthesis of the present invention As described above, the dental prosthesis of the present invention is used by adhering it to an adherend, such as a tooth, that has adhesive properties with respect to the dental adhesive, using an adhesive system consisting of a combination of a pretreatment agent containing a silane coupling agent and a dental adhesive, such as dental resin cement, that contains a component that reacts with or has high affinity with the silane coupling agent.

[0056] As the pretreatment agent in the adhesive system, one containing a silane coupling agent having a polymerizable group can be preferably used from the viewpoints of adhesion to dental resin cement, which is a general-purpose dental adhesive, and ease of handling. As such silane coupling agents, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltri(trimethylsiloxy)silane, ω-methacryloxydecyltrimethoxysilane, and γ-methacryloxypropylpentamethyldisiloxane are particularly preferably used.

[0057] In addition, as a dental adhesive, a dental adhesive composition such as dental resin cement containing 100 parts by mass of a polymerizable monomer such as bisphenol A dimethacrylate or triethylene glycol dimethacrylate, 100 to 400 parts by mass of an inorganic filler such as silica and / or a silicon-based composite oxide, and 0.001 to 10 parts by mass of a polymerization initiator such as a chemical polymerization initiator formed by a combination of benzoyl peroxide and an amine compound and / or a photopolymerization initiator formed by a combination of camphorquinone and an amine compound is preferably used.

[0058] 6. A ceramic article (hereinafter referred to as "a ceramic article") in which a part of the surface layer region of a body made of ceramics consisting of inorganic oxides that does not substantially contain silicon dioxide is composited with silicon dioxide. Articles of the Invention " (also called ") About the manufacturing method The adhesiveness problems of conventional zirconia prostheses are not limited to zirconia prostheses, but are also observed in ceramics made of inorganic oxides substantially free of silicon dioxide. It is believed that the adhesiveness of these ceramics can be improved by the composite bonding surface layer obtained by the dental prosthesis manufacturing method of the present invention. The method for manufacturing an article of the present invention was conceived based on this concept and is a method for manufacturing a ceramic article having a main body made of ceramics made of inorganic oxides substantially free of silicon dioxide, the surface layer region of which is composited with silicon dioxide. The method includes the steps of: (1) manufacturing a semi-finished product having a shape corresponding to the main body; (2) processing, as necessary, a microporous molded body made of a molded body of a raw material composition containing an inorganic powder serving as a raw material for the ceramic constituting the main body, or a heat-treated microporous molded body obtained by heat-treating the microporous molded body; (3) infiltrating a predetermined surface layer region of the semi-finished product with a treatment liquid consisting of an aqueous solution of alkali metal silicate; and (4) sintering the semi-finished product after the treatment step.

[0059] The raw material composition containing the inorganic powder serving as the ceramic raw material may be an inorganic powder raw material composition consisting solely of inorganic components, or an organic component-containing raw material composition obtained by adding an organic component such as a binder to the inorganic powder raw material composition. Examples of the microporous molded body include a microporous molded body obtained by compression molding the inorganic powder raw material composition. Examples of the heat-treated microporous molded body include a green body obtained by molding the organic component-containing raw material composition and then degreasing it (a microporous degreased body), and a pre-green body that is calcined either directly or after degreasing (a microporous calcined body). The degree of microporosity is not particularly limited as long as it allows a treatment solution applied to the surface to penetrate into the interior and retain the treatment solution to a predetermined depth from the surface, specifically, a range of 5 to 300 μm, preferably a range of 10 to 200 μm. Typically, the average pore diameter is within a range of 50 to 200 nm.

[0060] In the method for manufacturing an article of the present invention, examples of the inorganic oxide constituting the main body include stabilized zirconia, partially stabilized zirconia, alumina, titania, etc. When a microporous pre-sintered body is used in the semi-finished product manufacturing process, the pre-sintering can be performed at a temperature lower than the sintering temperature of the inorganic oxide, as described in Section 2-1, "(2) Regarding the Manufacturing Method of Zirconia Dental Mill Blanks." The processing step can be performed similarly to the processing step in the method for manufacturing a dental prosthesis of the present invention, and the sintering step can be performed at a sintering temperature that produces a dense sintered body, depending on the type of inorganic oxide. For example, to manufacture a ceramic article composed of alumina, alumina powder (Taimicron TM-DAR, manufactured by Taimei Chemical Industry Co., Ltd.) with an average particle size of 0.12 μm and a purity of 99.99% is molded and pre-sintered at 800°C for 1 hour to obtain a pre-sintered body with a relative density of 63%. Next, the same treatment steps as in the method for producing a dental prosthesis of the present invention are carried out, and the resultant product is sintered at 1400° C. for 2 hours, thereby producing a ceramic article made of the alumina. [Example]

[0061] The present invention will be specifically described below with reference to examples and comparative examples, although the present invention is not limited to these examples.

[0062] Example 1 [Production of zirconia-based ceramic articles] As the mill blank, "Katana Zirconia UTML (manufactured by Kuraray Noritake Dental)," a zirconia mill blank having a cutting portion made of a partially stabilized zirconia microporous calcined body, was used. Data was created so that a disk-shaped body of a predetermined size of 11 mm in diameter and 4 mm in thickness (specifically, a 1 cm x 1 cm x 3 mm plate-shaped body or a disk-shaped body of 11 mm in diameter and 4 mm in thickness) would be obtained after sintering, and cutting was performed to produce plate-shaped semi-finished products 1 and 2 of different sizes (corresponding to simulated semi-finished products of zirconia prostheses). Next, for each of these plate-shaped semi-finished products 1 and 2, one surface was used as a simulated bonding surface, and a treatment solution consisting of "No. 3 sodium silicate (manufactured by Toso Sangyo, an aqueous solution of 28 to 30 mass% silicon dioxide and 9 to 10 mass% sodium oxide: SiO2 / Na2O = 3.05)" was applied to the simulated bonding surface using a disposable sponge. 2 0.02 g was applied per sample. The sample was then dried at room temperature for 5 minutes and sintered. Sintering was performed by increasing the temperature from 25°C to 1550°C at a rate of 10°C / min, holding the temperature at 1550°C for 2 hours, and then decreasing the temperature from 1550°C to 25°C at a rate of 10°C / min. Using this method, a zirconia-based ceramic article 1 for analysis samples was produced, consisting of a 1 cm x 1 cm x 3 mm plate (corresponding to a simulated zirconia prosthesis), and a zirconia-based ceramic article 2 for physical property evaluation samples was produced, consisting of a disk-shaped object with a diameter of 11 mm and a thickness of 4 mm.

[0063] [Analysis of zirconia-based ceramic product 1] One surface layer of the zirconia-based ceramic article 1 was measured using X-ray diffraction (XRD) to confirm the presence of a silicon dioxide layer. Furthermore, measurement using an electron probe microanalyzer (EPMA) confirmed that the penetration depth of the silicon dioxide was 54 μm, and that no alkali metal oxides derived from alkali metal silicates were detected.

[0064] [Adhesion evaluation of zirconia-based ceramic article 2] The bonding surface of the zirconia-based ceramic article 2 was polished with #800 waterproof abrasive paper. Then, a double-sided tape with a 4 mm diameter hole was attached to the polished surface. The bonding surface exposed through the hole in the double-sided tape was then treated with "Tokuyama Universal Primer (manufactured by Tokuyama Dental)," a pretreatment agent containing a silane coupling agent, according to the manufacturer's instructions. A SUS304 round bar (diameter 8 mm, height 18 mm) that had been polished in advance using dental resin cement "Estecem II (manufactured by Tokuyama Dental)" was then bonded to the bonding surface.

[0065] After bonding, the dental resin cement was left in a thermostatic bath maintained at 37°C and 100% humidity for approximately one hour to allow chemical polymerization.The test piece was then immersed in 37°C water and removed after 24 hours to serve as the initial sample.The test piece removed after 24 hours was then immersed alternately in a water bath with a water temperature of 5°C and then in a water bath with a water temperature of 55°C for 30 seconds each, completing one set of immersion treatments.This immersion treatment was repeated 10,000 times, and the test piece was then used as the durability sample.

[0066] The tensile adhesive strength of these samples was measured using an autograph (crosshead speed 1 mm / min) manufactured by Shimadzu Corporation. For each example and comparative example, the measured values ​​of four samples were averaged to obtain the measurement results. As a result of the measurement, the adhesive strength of the initial sample was 30 MPa, and that of the durable sample was 20 MPa.

[0067] Comparative Example 1 A disk-shaped semi-finished product was prepared in the same manner as for zirconia-based ceramic article 2 described in Example 1 using "Katana Zirconia UTML (manufactured by Kuraray Noritake Dental)," and zirconia-based ceramic article 3 was produced in the same manner as for zirconia-based ceramic article 2 described in Example 1, except that the treatment with the treatment liquid (coating and drying) was not carried out, and an adhesive strength evaluation was carried out. The measurement results showed that the adhesive strength of the initial sample was 20 MPa, and that of the durability sample was 10 MPa.

Claims

1. A dental prosthesis having a main body comprising a "stabilized zirconia sintered body or partially stabilized zirconia sintered body" which contains zirconium oxide and at least one stabilizer selected from the group consisting of yttrium oxide, calcium oxide, magnesium oxide, cerium oxide, and erbium oxide, and which is substantially free of silicon dioxide; and a "composite" in which the "stabilized zirconia sintered body or partially stabilized zirconia sintered body" is combined with "silicon dioxide," the surface of the body has an adhesive surface to be adhered to an adherend and an exposed surface exposed to the surface; When the range of a depth from the surface to 5 to 300 μm is defined as the surface layer portion, in the surface layer portion of the adhesive surface, the “silicon dioxide” present in the surface layer portion and the “stabilized zirconia sintered body or partially stabilized zirconia sintered body” are combined to form the “composite”, The portion of the main body other than the surface layer portion is made of the "stabilized zirconia sintered body or partially stabilized zirconia sintered body", A dental prosthesis characterized by:

2. A method for producing a dental prosthesis according to claim 1, comprising the steps of: a cutting process step of cutting a zirconia dental mill blank having a cuttable portion made of a microporous calcined body of stabilized zirconia or a microporous calcined body of partially stabilized zirconia, the microporous calcined body containing zirconium oxide and at least one stabilizer selected from the group consisting of yttrium oxide, calcium oxide, and magnesium oxide, and substantially no silicon dioxide component, using a CAD / CAM system to obtain a semi-finished product made of the microporous calcined body, the semi-finished product having a shape corresponding to the shape of a desired dental prosthesis; a treatment step of applying a treatment liquid consisting of an aqueous solution of alkali metal silicate to a surface of the semi-finished product corresponding to the adhesive surface and allowing the treatment liquid to penetrate the surface, thereby retaining the alkali metal silicate on the surface layer of the surface; and a sintering step of sintering the semi-finished product that has been subjected to the treatment step at a temperature of 1200 to 1800°C; a method for producing the dental prosthesis, comprising:

3. the microporous calcined body constituting the cutting portion of the zirconia dental mill blank is a microporous calcined body having a relative density of 45 to 65% and pores that are open to the outside, the treatment liquid is a sodium silicate aqueous solution having a sodium silicate concentration of 15 to 70 mass %, In the treatment step, sodium silicate is retained in a surface layer portion of the surface up to a depth of 5 to 300 μm. A method for manufacturing a dental prosthesis according to claim 2.

4. A dental prosthesis manufacturing kit for manufacturing the dental prosthesis according to claim 1 by the method according to claim 2, comprising: a zirconia dental mill blank having a cutting portion made of a microporous calcined body of stabilized zirconia or a microporous calcined body of partially stabilized zirconia, which contains zirconium oxide and at least one stabilizer selected from the group consisting of yttrium oxide, calcium oxide, and magnesium oxide, and is substantially free of silicon dioxide; a treatment liquid comprising an aqueous sodium silicate solution having a sodium silicate concentration of 15 to 70 mass %; A dental prosthesis manufacturing kit comprising:

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