JP2017128466A - Zirconia sintered body and dental product, and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zirconia sintered body and a dental product having uniform translucency up to the inside, and a method for producing the same.SOLUTION: There is provided a sintered body of partially stabilized zirconia comprising 5 mol% to 8 mol% of yttria as a stabilizer. When a translucency ΔL of the outside of the sintered body is defined as ΔL, and a translucency ΔL of the inside of the sintered body is defined as ΔL, and a change rate from ΔLto ΔLis expressed by the following formula: [ΔL change rate]=(ΔL-ΔL)/ΔL×100, the ΔL change rate is -15% or more. For an Lvalue of chromaticity (color space) of the inside and the outside in Labcolor system (JISZ8781), using F11 as a light source, with the background of a sample to be white, the Lvalue is measured and set as a first Lvalue. For the same sample, for which the first Lvalue has been measured, with the sample background changed to black, an Lvalue is measured and set as a second Lvalue, where ΔL is a value obtained by subtracting the second Lvalue from the first Lvalue.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a zirconia sintered body and a method for producing the same. Moreover, this invention relates to the dental product containing a zirconia sintered compact, and its manufacturing method.

  In recent years, sintered products of zirconium oxide (zirconia) particles (zirconia) instead of metal as dental products (coated crowns, crowns, crowns, dentures and other prosthetics) from the viewpoint of aesthetics and safety A ceramic material such as a sintered body is used.

  Patent Document 1 discloses a block member for producing a dental prosthesis. The block member described in Patent Document 1 is a ceramic pre-sintered (calcined) at a temperature of 900 ° C. to 1000 ° C. When producing a prosthesis using the block member described in Patent Document 1, after producing a molded body from the block member by cutting, the molded body is finish-sintered in order to obtain the required dimensions and final hardness. The

JP 2007-314539 A

  The following analysis is given from the perspective of the present invention.

  When making a prosthesis with a sintered body of a ceramic material that can be directly machined, such as a glass ceramic material, the prosthesis creates a block of a sintered body of glass ceramic material and then blocks the block. It is formed into a predetermined shape by direct machining (for example, cutting). In this case, sintering after molding may be unnecessary.

  On the other hand, the conventional zirconia sintered bodies have high strength, and if the zirconia sintered bodies are machined directly, the cutting tool is immediately damaged, which is not profitable. For this reason, when producing a prosthesis with a conventional zirconia sintered body, first, a block in a state where the zirconia particles have not been sintered (calcined body), such as the block member described in Patent Document 1, is produced. Has been. Next, the prosthesis is formed by machining the block. And the prosthesis as a zirconia sintered compact is produced by baking the molded object of the calcined body produced in this way on sintering conditions.

  However, the method for producing a zirconia sintered prosthesis as described above has the following problems. When treating a patient with a zirconia sintered prosthesis, a dentist first examines the patient and determines the shape of the prosthesis. Next, after the dental technician forms the zirconia calcined body into the shape, the shaped body is fired to produce a prosthesis of the zirconia sintered body. However, in order to make a zirconia calcined body into a zirconia sintered body, for example, it is necessary to fire the calcined body at a temperature of 1400 ° C. or higher. Such high temperature firing requires time and equipment. For this reason, it is difficult to perform from molding to sintering in a dental clinic within a few hours. Therefore, it takes several days from the examination for determining the shape of the prosthesis to the examination for treatment using the completed prosthesis. That is, with this method, the patient cannot complete treatment within the day of the visit and must return to the hospital after a few days.

  When the zirconia calcined body becomes a zirconia sintered body, the calcined body usually contracts by about 20%. The calcined body is formed on the assumption of this shrinkage, but there may be a case where the shape of the sintered body serving as the prosthesis cannot be accurately matched with the originally planned shape.

  Therefore, in order to shorten the production time of the prosthesis and to produce the prosthesis with high accuracy, instead of processing the zirconia calcined body, the zirconia sintered body is directly processed to form the prosthesis. It is hoped to do.

  Therefore, when an attempt was made to produce a block of a zirconia sintered body that could be processed directly, a new problem was found. The size of the block for making a dental product needs to be larger than at least one tooth. However, it has been found that when a block of a zirconia sintered body having a certain size is produced, it cannot be sufficiently sintered to the inside of the block under general sintering conditions. Usually, the zirconia calcined body does not have transparency, but the zirconia sintered body has higher transparency than the calcined body. However, if the inside of the block is not sufficiently sintered, the transparency inside the block is lowered. When a dental product is molded using such a poorly sintered block, the dental product will be made in an interior region where this sintering is insufficient. In this case, for example, a dental product with low transparency is obtained, and it becomes difficult to reproduce transparency like natural teeth. Therefore, there is a need for a zirconia sintered body that is sufficiently sintered to the inside of the block and a manufacturing method thereof.

According to the 1st viewpoint of this invention, the sintered compact of the partially stabilized zirconia containing 5 mol%-8 mol% yttria as a stabilizer is provided. An external light-transmitting [Delta] L of the sintered body is expressed as [Delta] L _1, the inside of the translucent [Delta] L of the sintered body is represented as [Delta] L _2, the change rate following equation from [Delta] L ₁ to ΔL _2: [ΔL Change rate] = (ΔL ₂ −ΔL ₁ ) / ΔL ₁ × 100, the change rate of ΔL is −15% or more. However, the outside is a portion from the outer surface during sintering to a depth of 4 mm. The inside is a portion deeper than 4 mm from the outer surface. For ^{L *} value of the internal and external ^L * ^a * ^{b *} chromaticity in the color system (JISZ8781) (color space) using the F11 as the light source, the ^{L *} value of the background of the sample were measured in the white first and 1 L ^* value, the same samples were measured first in the L ^* value, when the L ^* value of the background of the sample were measured in the black and the second L ^* value, [Delta] L is first This is a value obtained by subtracting the second L ^* value from the L ^* value.

  According to the 2nd viewpoint of this invention, a dental product provided with the zirconia sintered compact which concerns on a 1st viewpoint is provided.

  According to a third aspect of the present invention, there is provided a method for producing a zirconia sintered body including a sintering step in which a zirconia composition containing 5 mol% to 8 mol% of yttria as a stabilizer is fired into a sintered body. Provided. In the sintering step, the rate of temperature increase from 1000 ° C. to the maximum temperature is 5 ° C./min or less.

  According to the 4th viewpoint of this invention, the manufacturing method of a dental product including the process process which shape | molds the zirconia sintered body produced by the manufacturing method of the zirconia sintered body which concerns on a 3rd viewpoint is provided.

  According to the method for producing a zirconia sintered body of the present invention, for example, even a zirconia sintered body having a size suitable for a dental product can obtain a zirconia sintered body sufficiently sintered to the inside. it can. For example, according to the method for producing a zirconia sintered body of the present invention, a zirconia sintered body having the same transparency as the outside can be obtained. According to this zirconia sintered body, since a dental product can be directly produced from the zirconia sintered body, the shape and dimensions of the dental product are determined as compared with the case of producing a dental product from a calcined body. Then, a dental product can be produced in a short time. Further, since it is not necessary to consider shrinkage during sintering, a dental product with high dimensional accuracy can be produced.

  According to the zirconia sintered body of the present invention, a dental product can be produced with sufficiently sintered zirconia. Therefore, for example, even if a dental product is formed from a zirconia sintered body by machining, a dental product having the same transparency as the outside of the sintered body, that is, a highly transparent dental product can be produced.

  According to the dental product of the present invention, a patient can be treated with a dental product having high transparency and high strength. Patients can also receive treatment with dental products that are more adapted to their oral environment.

The schematic perspective view of a zirconia sintered compact. The schematic diagram which shows the measuring method of chromaticity (color space). The schematic perspective view of a dental product.

  In the following description, reference numerals of the drawings are added for understanding of the invention and are not intended to be limited to the illustrated embodiments. Further, the illustrated shapes, dimensions, scales, and the like do not limit the invention to the forms shown in the drawings. In each embodiment, the same elements are denoted by the same reference numerals.

  The preferable form of each said viewpoint is described below.

  According to a preferred form of the first aspect, the change rate of ΔL is −10% or more.

  According to a preferred form of the first aspect, the change rate of ΔL is −5% or more.

According to a preferred embodiment of the first aspect, the zirconia sintered body has a cross section with a cross-sectional area of 900 mm ² or less. The shortest passing length in the cross section is 30 mm or less.

  According to a preferred form of the first aspect, the zirconia sintered body has an average crystal grain size of 5 μm or more.

  According to a preferred embodiment of the first aspect, the zirconia sintered body has a hexahedral or cylindrical shape.

  According to a preferred form of the second aspect, the dental product further includes an attachment for attaching to the processing apparatus. The fixture is joined to the zirconia sintered body.

  According to the preferable form of the second viewpoint, the zirconia sintered body has a hexahedral shape or a cylindrical shape.

  According to a preferred form of the second aspect, the zirconia sintered body has a crown shape.

  According to a preferred embodiment of the third aspect, the temperature raising rate is 3 ° C./min or less.

  According to a preferred embodiment of the third aspect, the maximum temperature is 1550 ° C. or higher.

  According to the preferred form of the third aspect, the method for manufacturing a zirconia sintered body further includes a forming step of forming into a hexahedral or cylindrical shape.

  According to a preferred embodiment of the third aspect, the method for producing a zirconia sintered body further includes a calcining step of producing a calcined body by firing the composition at a temperature that does not result in sintering. In the sintering step, the calcined body is fired.

  According to the preferable form of the third viewpoint, the sintering is performed in an atmosphere having an oxygen concentration higher than that of air.

  According to a preferred embodiment of the fourth aspect, the method for manufacturing a dental product further includes a step of joining an attachment for attaching to the processing apparatus to the zirconia sintered body. In the processing step, the zirconia sintered body is formed by a processing apparatus.

  According to the preferred form of the fourth aspect, in the processing step, the zirconia sintered body is formed into a crown shape.

The zirconia sintered body according to the first embodiment of the present disclosure will be described. The zirconia sintered body of the present disclosure is a sintered body in which partially stabilized zirconia crystal particles containing zirconium oxide (ZrO ₂ ; zirconia) and a stabilizer thereof are mainly sintered, and the partially stabilized zirconia is used as a matrix phase. Have as. In the zirconia sintered body of the present disclosure, the main crystal phase of zirconia is at least one of a tetragonal system and a cubic system. Zirconia may contain both tetragonal and cubic systems. It is preferable that the zirconia sintered body does not substantially contain a monoclinic system in a stage where the hydrothermal treatment test is not performed.

  The zirconia sintered body of the present disclosure includes not only a sintered body obtained by sintering molded zirconia particles under normal pressure or non-pressurization, but also HIP (Hot Isostatic Pressing) treatment, etc. A sintered body densified by high-temperature pressure treatment is also included.

Examples of the stabilizer in partially stabilized zirconia include calcium oxide (CaO), magnesium oxide (MgO), yttrium oxide (Y ₂ O ₃ ) (hereinafter referred to as “yttria”), cerium oxide (CeO ₂ ), and the like. The oxide of this is mentioned. In order to increase the transparency of the zirconia sintered body, it is more preferable to use yttria. When using yttria as a stabilizer, the content of yttria is preferably 4 mol% to 8 mol% with respect to partially stabilized zirconia, for example. According to this content rate, the phase transition to the monoclinic crystal can be suppressed and the transparency of the zirconia sintered body can be increased. The yttria content is more preferably 5.5 mol% or more with respect to partially stabilized zirconia in order to increase transparency. In order to maintain the strength, the yttria content is more preferably 7.5 mol% or less with respect to the partially stabilized zirconia. The content of the stabilizer in the zirconia sintered body can be measured by, for example, inductively coupled plasma (ICP) emission spectroscopy, fluorescent X-ray analysis, or the like. Note that zirconia partially stabilized by adding a stabilizer is called partially stabilized zirconia (PSZ).

  In the zirconia sintered body, it is preferable that the stabilizer is uniformly distributed. That is, in the zirconia sintered body, the content of the stabilizer is preferably constant. For example, in the zirconia sintered body, it is preferable that the content of the stabilizer is not changed stepwise or partially. This is because when the content of the stabilizer is partially different, the shrinkage rate during sintering is different, and a defect occurs in the zirconia sintered body. The variation of the stabilizer is preferably 1 mol% or less, and more preferably 0.5 mol% or less.

The zirconia sintered body preferably contains components other than the colorant and the fluorescent agent to such an extent that the transparency described later is not impaired. For example, the content of the components other than the colorant and the fluorescent agent is preferably less than 1 part by mass and less than 0.5 parts by mass with respect to 100 parts by mass of the total mass of zirconia and the stabilizer. More preferably, it is more preferable if it is less than 0.1 mass part, and it is still more preferable if it does not contain substantially. For example, the zirconia sintered body may be substantially free of aluminum oxide (Al ₂ O ₃ ; alumina) (for example, 0 part by mass).

The zirconia sintered body preferably has a cross section of 28 mm ² or more, more preferably a cross section of 50 mm ² or more, and further preferably a cross section of 78 mm ² or more. The shortest span length in the cross section is preferably 6 mm or more, more preferably 8 mm or more, and further preferably 10 mm or more. When a cylindrical sintered body having a cross section with a diameter of 6 mm or more is manufactured by a conventional manufacturing method (for example, a manufacturing method including a firing step with a temperature increase rate of 10 ° C./min or more), the internal translucency is Although it becomes lower than the translucency of the surface, it is because the fall of internal translucency can be suppressed according to the manufacturing method of this indication.

The zirconia sintered body preferably has a cross section of 900 mm ² or less, more preferably has a cross section of 625 mm ² or less, and more preferably has a cross section of 400 mm ² or less. The shortest span length in the cross section is preferably 30 mm or less, more preferably 25 mm or less, and further preferably 20 mm or less. This is because in a sintered body having a square cross section (cross-sectional area 900 mm ² ) having a side of 30 mm or more, a phenomenon occurs in which the translucency inside becomes lower than the translucency on the surface.

The zirconia sintered body of the present invention can have, for example, a cylindrical body, a polygonal column, a hexahedron, or the like. The cylindrical body includes not only a circular bottom surface but also an elliptical shape and circular and elliptical similar shapes. FIG. 1 shows a schematic perspective view of a zirconia sintered body having a rectangular parallelepiped shape. When the shape of the zirconia sintered body 1 is a rectangular parallelepiped, the dimensions are, for example, length d ₁ 13 mm to 17 mm, width (depth) d ₂ 15 mm to 19 mm, and height (thickness) d ₃ 18 mm to 32 mm. be able to.

  In the zirconia sintered body of the present invention, it is preferable that the difference between the internal translucency and the external translucency is small. In the present specification, the outside of the zirconia sintered body refers to a portion within a depth of 4 mm from a non-processed as-sintered surface after sintering. Moreover, the inside of a zirconia sintered compact means the part deeper than 4 mm in depth from the unprocessed outer surface after sintering. The outer surface is preferably a surface that intersects the above-described cross section.

  The translucency inside and outside the zirconia sintered body can be expressed by ΔL described below. A large ΔL indicates that the transparency of the zirconia sintered body is high, and a small ΔL indicates that the transparency of the zirconia sintered body is low.

The above ΔL will be described. Translucent zirconia sintered body (transparency) ^can be expressed using the ^{L *} values of chromaticity (color space) in the L ^* a * ^{b *} color system (JISZ8781). FIG. 2 is a schematic diagram for explaining a chromaticity measurement method. L ^* a ^* b ^* L ^{* of the} color system was measured with the background (underlay) 22 of the sample (for example, zirconia sintered body) 20 made white (the side opposite to the measurement device 21 was white with respect to the sample 20) ^. Let the value be the first L ^* value. For the same sample 20 measured a first L ^* value, the background of the sample 20 (underlayment) 22 in the black (the measuring device 21 opposite to the black with respect to the sample 20) measured L ^* a ^* The L ^* value of the b ^* color system is the second L ^* value. In the present disclosure, the difference between the first L ^* value and the second L ^* values (first L ^* value value obtained by deducting the second L ^* value from) is denoted by [Delta] L. For the black and white used as the background (underlay) 22 in the chromaticity measurement, a concealment ratio measuring sheet used for measurement relating to the paint can be used.

The rate of change from ΔL outside the zirconia sintered body (denoted as “ΔL ₁ ”) to ΔL inside the zirconia sintered body (denoted as “ΔL ₂ ”) can be expressed by the following equation.
[Change rate of ΔL (%)] = (ΔL ₂ −ΔL ₁ ) / ΔL ₁ × 100

In the zirconia sintered body, the change rate of ΔL when F11 is used as a light source and a masking mask having a hole diameter of 8 mm is used is preferably −15% or more, more preferably −14% or more, It is more preferably -13% or more, more preferably -10% or more, more preferably -5% or more, more preferably -3% or more, and further preferably -1% or more. By reducing the difference in translucency between the inside and the outside, a highly translucent prosthesis can be cut out from the inside of the sintered body. According to the test in the present invention, the fact that the internal translucency of the zirconia sintered body is higher than the external translucency (that is, the rate of change becomes a positive value) is not a measurement error. It is considered difficult to occur. ΔL ₁ and ΔL ₂ are values when the zirconia sintered body does not contain a colorant, a fluorescent agent, and an opaque agent.

  In the zirconia sintered body, the crystal grain size of zirconia is preferably 1.5 μm or more, preferably 3 μm or more, more preferably 5 μm or more, more preferably 7 μm or more, and 8 μm or more. More preferably, it is more preferably 9 μm or more. The crystal grain size of zirconia is preferably 40 μm or less, more preferably 30 μm or less, and further preferably 20 μm or less. By setting the crystal grain size within the above range, it is considered that cutting with respect to the zirconia sintered body can be facilitated and transparency and strength described later can be maintained.

  The crystal grain size of zirconia can be calculated, for example, as an average particle size obtained by observing a cross section of the zirconia sintered body with a scanning electron microscope (SEM). For example, on the SEM cross-sectional image, all zirconia particles in which all the contours appear (the contours are not interrupted) are picked up. Next, the cross-sectional area on the SEM photograph is calculated for each picked up particle. Then, the particle diameter (diameter) when the zirconia particles are assumed to be circular on the SEM cross-sectional image is calculated based on the cross-sectional area of each particle. The average crystal grain size can be calculated based on the calculated grain size. In addition, said preferable particle size is a numerical value of a state without a hydrothermal treatment test.

In the zirconia sintered body, the density measured in accordance with JIS R1634 can be set to, for example, 5.8 g / cm ³ or more. Moreover, the said density can be made into 6.1 g / cm < ³ > or less, for example.

  The bending strength measured according to JISR1601 in the zirconia sintered body of the present invention is preferably 200 MPa or more, more preferably 300 MPa or more, and further preferably 400 MPa or more. The bending strength is preferably 1200 MPa or less, more preferably 1000 MPa or less, and further preferably 800 MPa or less. By making bending strength into the said range, while being able to make the cutting process with respect to a zirconia sintered compact easy, the intensity | strength as a dental prosthesis can be maintained. In addition, said preferable bending strength is a numerical value of a state without a hydrothermal treatment test.

  The workability of the zirconia sintered body is preferably 5 times or higher, more preferably 8 times or higher, more preferably 9 times or higher compared to the zirconia sintered body made from the zirconia powder ZpexSmile manufactured by Tosoh Corporation. Preferably, 12 times or more is more preferable, and 16 times or more is more preferable. The workability can be measured, for example, by using a processing apparatus with a single processing amount in which the zirconia sintered body can be processed with a processing tool (bar) (used simultaneously). By improving the workability, the processing cost of the dental product can be suppressed and the processing time can be shortened.

Also, the workability of the zirconia sintered body is determined by using two cutting tools simultaneously used with the CERON MC XL made by sirona, the Celec step bar 12S (for MCXL) and the Celec cylinder pointed bar 12S (for MCXL). preferably the cuttable volume is 2 mm ³ or more, more preferably 4 mm ³ or more, more preferably 5 mm ³ or more and further preferably 8 mm ³ or more.

The zirconia sintered body can contain at least one of a colorant (pigment) and a fluorescent agent. Examples of the colorant include P, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Y, Zr, Sn, Sb, Bi, Ce, Pr, Sm, Eu, Gd, Tb, and Er. An oxide of at least one element selected from Examples of the fluorescent agent include Y ₂ SiO ₅ : Ce, Y ₂ SiO ₅ : Tb, (Y, Gd, Eu) BO ₃ , Y ₂ O ₃ : Eu, YAG: Ce, ZnGa ₂ O ₄ : Zn, BaMgAl ₁₀ O ₁₇ : Eu and the like can be mentioned.

  In the case where the zirconia sintered body is insufficiently or difficult to be specified due to the structure or characteristics depending on the crystal grain size, composition, etc., the zirconia sintered body may be specified in addition to the structure or characteristics, or by the manufacturing method alone described below. This is useful for specifying the zirconia sintered body of the present invention. For example, the zirconia sintered body according to the present invention includes a zirconia sintered body produced by firing at a firing temperature of 1000 ° C. or higher and a heating rate of 5 ° C./min or less, a zirconia sintered body fired at 1550 ° C. or higher, It can be specified as a zirconia sintered body or the like fired at a temperature for 1 hour or more.

  According to the first embodiment, even a prosthesis manufactured by directly cutting a zirconia sintered body, it is possible to manufacture a prosthesis having the same translucency as the outside of the block of the zirconia sintered body. it can. For example, according to the first embodiment, a highly translucent prosthesis can be produced by direct processing of a zirconia sintered body.

  By allowing direct processing of the zirconia sintered body, for example, a prosthesis can be produced in a dental clinic where a patient has been hospitalized. Thereby, the patient can complete the treatment in a short time, for example, within the hospital day.

  In addition, by allowing direct processing of the zirconia sintered body, the shape and dimensions of the prosthesis can be determined without considering sintering shrinkage. Thereby, the prosthesis suitable for a patient's oral cavity environment can be produced.

  Next, a dental product according to the second embodiment of the present disclosure will be described. FIG. 3 shows a schematic perspective view of the dental product of the present disclosure. The dental product 10 is, for example, set in a processing apparatus (not shown) to produce a dental prosthesis or the like. The dental product 10 includes a zirconia sintered body 1 and an attachment 11 attached to the zirconia sintered body 1. The zirconia sintered body 1 can be a zirconia sintered body according to the first embodiment of the present disclosure. The attachment 11 is a component for setting the zirconia sintered body 1 to a processing apparatus. The attachment 11 is in accordance with the specifications of the processing apparatus. Any form of joining the zirconia sintered body 1 and the fixture 11 can be adopted as long as it does not hinder the production of the prosthesis. For example, the zirconia sintered body 1 and the fixture 11 can be joined with an adhesive.

  According to the second embodiment, a prosthesis using the zirconia sintered body according to the first embodiment can be easily manufactured.

  Next, a dental product according to the third embodiment of the present disclosure will be described. The dental product according to the third embodiment can be manufactured from the zirconia sintered body according to the first embodiment or the dental product according to the second embodiment. Dental products include, for example, prosthetics such as ceramic frames and full cantour crowns. The zirconia sintered body can have a crown shape. The dental product may further include porcelain (for example, glass material) (not shown) laminated on the zirconia sintered body. Further, the dental product can be, for example, an orthodontic product (for example, an orthodontic bracket) or a dental implant product (for example, an abutment for a dental implant).

  According to the third embodiment, the zirconia sintered body has high transparency and can be more adapted to the oral environment of the patient.

  Next, the composition and calcined body for producing the zirconia sintered body of the present disclosure will be described. The composition and the calcined body serve as a precursor (intermediate product) of the above-described zirconia sintered body of the present invention. The calcined body is obtained by firing (that is, calcining) the composition at a temperature that does not lead to sintering. In addition, the calcined body includes a molded product. For example, a dental product (for example, a crown-shaped prosthesis) obtained by processing a calcined zirconia disk with a CAD / CAM (Computer-Aided Design / Computer-Aided Manufacturing) system is also included in the calcined body.

  The composition of the present disclosure includes a powder, a fluid obtained by adding the powder to a solvent, and a molded body obtained by molding the powder into a predetermined shape. That is, the composition may be in the form of a powder, or a paste or a wet composition (that is, it may be in a solvent or may contain a solvent). The composition may contain additives such as a binder and a pigment. In addition, in the calculation of the content rate, the mass of additives such as a solvent and a binder is not considered. When the composition of the present disclosure is a molded body, it may be molded by any molding method, for example, may be molded by press molding, injection molding, stereolithography, It may be molded. For example, the composition of the present invention may be subjected to press molding and further subjected to CIP (Cold Isostatic Pressing) treatment.

  The molded product can be molded so as to have a shape and a dimension corresponding to the sintered body to be produced in consideration of shrinkage during sintering.

  The composition and calcined body of the present disclosure contain partially stabilized zirconia. The kind and content of the stabilizer in the composition and calcined body can be the same as described above. In the composition and the calcined body, the variation in the content of the stabilizer (for example, yttria) is preferably small. For example, the variation in the content of the stabilizer is preferably 1 mol% or less, more preferably 0.5 mol%, and even more preferably when a significant difference cannot be detected.

  The molded composition (molding composition) and calcined body of the present disclosure have the same configuration as the zirconia sintered body to be produced.

  The composition of the present disclosure becomes the calcined body of the present disclosure by firing the composition of the present invention at, for example, 800 ° C. to 1200 ° C. under normal pressure.

  The composition and calcined body of the present disclosure become the zirconia sintered body of the present disclosure by firing at 1400 ° C. to 1700 ° C., for example, under normal pressure.

  According to the composition and calcined body of the present disclosure, the zirconia sintered body of the present disclosure can be produced.

  Next, the manufacturing method of a zirconia sintered compact, a zirconia calcined body, a zirconia composition, and the manufacturing method of a dental product are demonstrated.

  First, zirconia and a stabilizer are wet mixed in water to form a slurry. Next, the slurry is dried and granulated. Next, the granulated product is calcined to produce a primary powder. Next, the primary powder is pulverized and mixed in water until a desired particle size is obtained to form a zirconia slurry. Next, the slurry is dried and granulated to produce a secondary powder to be a composition.

  Next, the secondary powder is press-molded to produce a molded product as a composition having a predetermined shape. The molded product may be further subjected to CIP treatment.

  When producing a calcined body, a molded object can be baked at 800 to 1000 degreeC, for example, and a calcined body can be produced. The molding may be performed by cutting or the like at the stage of the calcined body. Molding can be performed with a CAD / CAM system.

  Next, the zirconia powder can be sintered by firing the molded product or calcined body at, for example, 1400 ° C. to 1650 ° C., preferably 1450 ° C. to 1600 ° C., to produce the zirconia sintered body of the present invention. it can. At the time of firing the molded product or calcined body for producing the sintered body, the temperature rise rate from the temperature at which the calcined body is formed, for example, 1000 ° C. to the sintering temperature (for example, the maximum firing temperature) is 5 It is preferably at most 0 ° C / minute, more preferably at most 3 ° C / minute, more preferably at most 2 ° C / minute, further preferably at most 1 ° C / minute. By producing a sintered body at such a temperature rising rate, a sintered body with improved translucency can be produced up to the inside of the sintered body. The maximum temperature is preferably 1500 ° C. or higher, more preferably 1550 ° C. or higher, and further preferably 1600 ° C. or higher. It is considered that the crystal grain size can be grown by increasing the maximum temperature. The holding time at the maximum temperature is preferably 1 hour or longer, and more preferably 2 hours or longer. It is considered that the crystal grain size can be grown by increasing the holding time to some extent. Then, by increasing the crystal grain size, it is possible to improve the translucency and workability of the sintered body.

  Firing for sintering can also be performed in an air (air) atmosphere. Further, the firing for sintering can be performed in an atmosphere having an oxygen concentration higher than that of air, for example, under aeration of oxygen gas. The flow rate of oxygen gas can be set as appropriate. Sintering can be promoted by aeration of oxygen gas.

  A dental product can be produced by joining a fixture to the produced zirconia sintered body. The fixture can be joined to the zirconia sintered body using, for example, an adhesive.

  In addition, a dental product having an attachment can be set in a processing apparatus such as a CAD / CAM system, and a zirconia sintered body can be formed into a predetermined shape such as the shape of a prosthesis using the processing apparatus. After the zirconia sintered body is formed, the fixture can be removed.

[Examples 1 to 11 and Comparative Examples 1 to 4]
A zirconia sintered body was produced, and the translucency of the inside and outside of the sintered body was compared. Further, the density, crystal grain size and machinability of the zirconia sintered body were measured. As Comparative Examples 1 to 3, the same measurement was performed on the zirconia sintered bodies produced by changing the heating rate. Moreover, in the comparative example 4, the same measurement was performed about the sintered compact which has a different dimension.

  A partially stabilized zirconia powder containing yttria having a content shown in Table 1 was prepared as a stabilizer. The raw materials of Examples 1 to 4 and 8 to 11 and Comparative Examples 1 to 4 are zirconia powders manufactured by Kuraray Noritake Dental Co., Ltd. The raw material of Example 5 is zirconia powder ZpexSmile manufactured by Tosoh Corporation. The raw material of Example 6 is Tosoh Corporation zirconia powder TZ-6YS. The raw material of Example 7 is Tosoh Corporation zirconia powder TZ-8YS. Table 1 shows the average particle diameter of the raw material powder. Next, the zirconia powder was formed into a rectangular parallelepiped shape, and fired under the atmosphere and normal pressure under the firing conditions shown in Table 1, to produce a zirconia sintered body having a rectangular parallelepiped shape having the dimensions shown in Table 2. The heating rate shown in Table 1 is a heating rate from 1000 ° C. to the maximum temperature.

  Next, a sample of 10 mm × 10 mm × 1.2 mm was cut out as the outside of the zirconia sintered body so that the outer surface during sintering was a large surface. Similarly, a 10 mm × 10 mm × 1.2 mm sample was cut out so as to include the center of the height (longer direction) as the inside of the zirconia sintered body. And the mirror surface processing was performed with respect to both surfaces (large surface) of the sample.

Next, chromaticity was measured for both the external and internal samples. Chromaticity, by using the chromaticity measuring machine (KONIKA MINOLTA Co. SPECTROPHOTOMETER CM-3610A) and analysis software (Spectra Magic NX), measuring a first ^{L *} value and the second ^{L *} value of the above, the It was calculated 1 ^{L *} value and a [Delta] L ₁ and [Delta] L ₂ is the difference of the second ^{L *} value. F11 was used as a light source, and a masking mask having a hole diameter of 8 mm was used. For black and white backgrounds (underlays), concealment ratio measuring paper used for measurement relating to paint was used. Based on the above equation, the change rate of ΔL was calculated from ΔL ₁ and ΔL ₂ . The results are shown in Table 2.

  About each zirconia sintered compact, the density was measured based on JISR1634. Table 3 shows the measurement results.

  About each zirconia sintered compact, based on the SEM image of the sintered compact cross section image | photographed using the scanning electron microscope, the particle size of the crystal | crystallization in an image was measured and the average value was computed. As the electron microscope, a field emission scanning electron microscope (FE-SEM) (S-4700) manufactured by Hitachi High-Tech Fielding Co., Ltd. was used. Table 3 shows the measurement results.

  About each zirconia sintered compact, volume which can be cut with two cutting tools used simultaneously, CEREC step bar 12S (for MCXL) and SEREC cylinder pointed bar 12S (for MCXL), using CERON MC XL made by sirona Was measured. The volume that can be cut is the amount of machining cut from the start of machining until the machining device automatically stops due to the inability to machine. Table 3 shows the measurement results.

  About Comparative Examples 1-4 whose temperature increase rate is 10 degree-C / min, the translucency change rate became -15% or less. On the other hand, in Examples 1 to 9 where the rate of temperature increase was 1 ° C./min, 3 ° C./min, and 5 ° C./min, the translucency change rate could be higher than −15%. In particular, when the rate of temperature increase was 1 ° C./min, there was a tendency that the translucency change rate could be increased. In Examples 2, 6 and 7, the translucency change rate can be set to -5% or more, and in Examples 3 and 4, the translucency change rate can be set to -1% or more. did it. Accordingly, by setting the rate of temperature rise in the region of 1000 ° C. or higher in the firing for sintering to less than 10 ° C./min, preferably 5 ° C./min or less, 3 ° C./min or less, or 1 ° C./min or less. It was found that the transparency inside the sintered body can be improved.

In Comparative Example 4 in which the size of the sample was 10 mm × 10 mm × 10 mm (cross-sectional area 100 mm ² , the shortest passing length 10 mm), the internal translucency was reduced. On the other hand, in Examples 1-10, even if it is a sample of 11 mm x 14 mm x 18 mm (cross-sectional area 154mm < ² >, shortest passing length 11mm) larger than the sample of the comparative example 4, the fall of internal translucency is suppressed. We were able to. Moreover, in Example 11, even if it was a sample of 30 mm x 30 mm x 30 mm (cross-sectional area 900mm < ² >, the shortest passing length 30mm), the fall of internal translucency could be suppressed.

Comparing the external translucency ΔL ₁ , in Examples ₁ to 4, 8, 9, and 11, ΔL ₁ is 19 or more, which can improve translucency more than other Examples and Comparative Examples. did it. This is considered to be influenced by the yttria content rate, the heating rate, and the maximum temperature.

In Examples 1-4 and 8-11, the zirconia sintered compact with high machinability was able to be obtained compared with Comparative Examples 1-4. For example, in Examples 1-4 and 8-11, 3 mm ³ or more could be cut, whereas in Comparative Examples 1-4, the cutting amount was less than 3 mm ³ .

  When Table 3 is seen, the tendency which can improve workability is seen when the crystal grain diameter of a sintered compact is enlarged. The crystal grain size is considered to be influenced by the zirconia raw material, the yttria content, the heating rate, and the maximum temperature. That is, according to Tables 1 and 3, using a zirconia raw material manufactured by Kuraray Noritake Dental Inc., increasing the yttria content (for example, 6 mol% or more), and decreasing the temperature rising rate at 1000 ° C or more (for example, 5 ° C / min It is considered that the crystal grain size can be increased by increasing the maximum firing temperature (1550 ° C. or higher).

  In Examples 1 to 4 and 8 to 11, zirconia sintered bodies having high machinability could be obtained. This is considered to be because the crystal grain size of the sintered body could be increased by using a zirconia raw material manufactured by Kuraray Noritake Dental Co., Ltd. and by setting the heating rate to less than 10 ° C./min. According to Examples 1-4, 8 and 9, a dental prosthesis having high translucency can be more easily produced from a block of a zirconia sintered body.

  Each disclosure of the above patent document is incorporated herein by reference. The zirconia sintered body and the manufacturing method thereof, and the dental product and the manufacturing method thereof according to the present invention have been described based on the above embodiment. Various disclosure elements (including each element of each claim, each element of each embodiment or example, each element of each drawing, etc.) within the frame and based on the basic technical idea of the present invention It goes without saying that modifications, changes and improvements of the above can be included. Various combinations and replacements of various disclosed elements (including each element of each claim, each element of each embodiment or example, each element of each drawing, etc.) within the scope of the entire disclosure of the present invention. Selection is possible.

  Further problems, objects, and developments of the present invention will become apparent from the entire disclosure of the present invention including the claims.

  Regarding the numerical ranges described in this document, any numerical values (including decimal places) or small ranges included in the range should be construed as being specifically described even if not otherwise stated. is there.

  A part or all of the above embodiment may be described as in the following supplementary notes, but is not limited to the following description.

  The zirconia sintered body of the present invention includes dental materials such as prostheses, optical fiber connection parts such as ferrules and sleeves, various tools (for example, grinding balls and grinding tools), various parts (for example, screws, bolts and nuts). ), Various sensors, electronic parts, ornaments (for example, watch bands), and the like. When using a zirconia sintered body as a dental material, for example, coping, framework, crown, crown bridge, abutment, implant, implant screw, implant fixture, implant bridge, implant bar, bracket, denture base, inlay, It can be used for onlays, onlays, straightening wires, laminate veneers and the like.

DESCRIPTION OF SYMBOLS 1 Zirconia sintered compact 10 Dental product 11 Attachment tool 20 Sample 21 Measuring apparatus 22 Underlay

Claims (19)

A partially stabilized zirconia sintered body containing 5 mol% to 8 mol% yttria as a stabilizer,
The translucent ΔL outside the sintered body is expressed as ΔL ₁ ,
The translucent ΔL inside the sintered body is expressed as ΔL ₂ ,
The rate of change from ΔL ₁ to ΔL ₂ is expressed as:
[Change rate of ΔL] = (ΔL ₂ −ΔL ₁ ) / ΔL ₁ × 100
When expressed by
The rate of change of ΔL is −15% or more,
However, the outside is a portion from the outer surface during sintering to a depth of 4 mm,
The inside is a portion deeper than 4 mm from the outer surface,
For the ^{L *} value of chromaticity (color space) in the internal and the external ^L * ^a * ^{b *} color system (JISZ8781), using the F11 as a light source, ^{L *} value measured background samples in the white Is the first L ^* value,
The same samples were measured first in the L ^* value, when the L ^* value of the background of the sample were measured in the black and the second L ^* value,
ΔL is a value obtained by deducting the second L ^* value from the first L ^* value, the zirconia sintered body.   The zirconia sintered body according to claim 1, wherein a change rate of ΔL is -10% or more.   The zirconia sintered body according to claim 1 or 2, wherein a change rate of ΔL is -5% or more. The cross-sectional area has a cross section of 900 mm ² or less,
The zirconia sintered body according to any one of claims 1 to 3, wherein a shortest passing length in the cross section is 30 mm or less.   The zirconia sintered body according to any one of claims 1 to 4, which has an average crystal grain size of 5 µm or more.   The zirconia sintered body according to any one of claims 1 to 5, which has a hexahedral or cylindrical shape.   A dental product comprising the zirconia sintered body according to any one of claims 1 to 5. It further includes an attachment for attaching to the processing device,
The dental product according to claim 7, wherein the fixture is joined to the zirconia sintered body.   The dental product according to claim 7 or 8, wherein the zirconia sintered body has a hexahedral shape or a cylindrical shape.   The dental product according to claim 7 or 8, wherein the zirconia sintered body has a crown shape. Including a sintering step of firing a zirconia composition containing 5 mol% to 8 mol% yttria as a stabilizer to form a sintered body,
The manufacturing method of the zirconia sintered compact whose temperature increase rate from 1000 degreeC to the maximum temperature is 5 degrees C / min or less in the said sintering process.   The manufacturing method of the zirconia sintered compact of Claim 11 whose said temperature increase rate is 3 degrees C / min or less.   The manufacturing method of the zirconia sintered compact of Claim 11 or 12 whose said maximum temperature is 1550 degreeC or more.   The manufacturing method of the zirconia sintered compact as described in any one of Claims 11-13 which further includes the shaping | molding process which shape | molds the said composition in a hexahedron or a cylindrical body shape. A calcining step of calcining the composition at a temperature that does not lead to sintering to produce a calcined body;
The method for producing a zirconia sintered body according to any one of claims 11 to 14, wherein the calcined body is fired in the sintering step.   The manufacturing method of the zirconia sintered compact as described in any one of Claims 11-15 which performs baking in the atmosphere whose oxygen concentration is higher than air in the said sintering process.   The manufacturing method of a dental product including the process process which shape | molds the zirconia sintered compact produced by the manufacturing method of the zirconia sintered compact as described in any one of Claims 11-16. The zirconia sintered body further includes a step of joining an attachment for attaching to a processing apparatus,
The method for manufacturing a dental product according to claim 17, wherein in the processing step, the zirconia sintered body is formed by the processing device.   The method for manufacturing a dental product according to claim 17 or 18, wherein, in the processing step, the zirconia sintered body is formed into a crown shape.

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