Translucency improving liquid containing indium for dental zirconia calcined body

Abstract

To provide a light-transmissivity improvement liquid for a dental zirconia calcined body that can give a zirconia sintered body high light-transmissivity comparable to that of natural tooth enamel and a method for use thereof.SOLUTION: A light-transmissive improvement liquid for a dental zirconia calcined body contains a solvent and an indium compound, with the content of the indium compound being 2.0 wt.%-20.0 wt.% in terms of indium relative to the total amount of the light-transmissive improvement liquid.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a solution for improving the translucency of dental zirconia calcined bodies and a method for using the same. [Background technology]

[0002] In recent years, the technology of fabricating prosthetic devices through cutting using dental CAD / CAM systems has rapidly become widespread. This has made it possible to easily fabricate prosthetic devices by processing workpieces made from ceramic materials such as zirconia, alumina, and lithium disilicate, or resin materials such as acrylic resin and hybrid resin.

[0003] Zirconia, in particular, has been used clinically in a variety of cases due to its high strength. However, sintered zirconia that can be used in the oral cavity (hereinafter referred to as zirconia sintered body) is so hard that it cannot be machined using dental CAD / CAM systems. For this reason, zirconia cutting bodies for dental machining are pre-sintered at a low firing temperature without final firing, and are adjusted to a hardness that allows for machining.

[0004] When zirconia first began to be used as a dental material, it was strong but had low translucency, and was mainly used for copings and frames. In recent years, with the development of zirconia with improved translucency (high translucency zirconia), its use has expanded from molars to full crowns in the anterior teeth. However, even highly translucent zirconia is not translucent enough to replicate the enamel of natural teeth. Therefore, in cases where aesthetics are particularly important, natural-looking restorations are created by layering porcelain on zirconia. In such a situation, it is desirable to obtain a more natural restoration using full-count zirconia. Therefore, there is a need to develop zirconia with better translucency.

[0005] Patent Document 1 discloses a translucency improving solution containing yttrium and a method for using the solution. By using the solution on a zirconia calcined body, the translucency of any desired part can be improved. However, even if the translucency is improved by using the solution, the translucency is still insufficient to reproduce the color tone of the enamel layer of natural teeth. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] DE102015103439 A1 Summary of the Invention [Problem to be solved by the invention]

[0007] There was a need for technology to give zirconia sintered bodies high translucency similar to that of natural tooth enamel. [Means for solving the problem]

[0008] The present inventors have investigated a translucency improving liquid for dental zirconia calcined body that can impart high translucency to a zirconia sintered body similar to that of natural tooth enamel.

[0009] The present invention provides a translucency improving liquid for a dental zirconia calcined body, which contains a solvent and an indium compound, and is characterized in that the indium compound is contained in an amount of 2.0 wt % to 20.0 wt % in terms of indium relative to the total amount of the translucency improving liquid for a dental zirconia calcined body. In the translucency improving liquid for dental zirconia calcined body of the present invention, the solvent may be water, alcohol, or a mixture thereof. The translucency improving liquid for dental zirconia calcined body of the present invention may contain a precipitating agent.

[0010] The present invention also provides a method for using the translucency improving liquid for a dental zirconia calcined body of the present invention, which comprises applying the translucency improving liquid for a dental zirconia calcined body to and / or impregnating the dental zirconia calcined body with the translucency improving liquid. The present invention also provides a method for using the translucency improving liquid for a dental zirconia calcined body of the present invention, which is characterized by applying the translucency improving liquid to the occlusal surface or incisal side of a dental zirconia calcined body having a cut tooth shape. In this case, the tooth-shaped dental zirconia calcined body can be in the form of an inlay, laminate, crown or bridge. [Effects of the Invention]

[0011] The translucency improving liquid for dental zirconia calcined body of the present invention can impart high translucency to a zirconia sintered body, similar to that of natural tooth enamel. DETAILED DESCRIPTION OF THE INVENTION

[0012] The translucency improving liquid for a dental zirconia calcined body of the present invention contains a solvent and an indium compound, and is characterized in that the indium compound is contained in an amount of 2.0 wt % to 20.0 wt % in terms of indium relative to the total amount of the translucency improving liquid for a dental zirconia calcined body.

[0013] The indium compound contained in the translucency improving liquid for dental zirconia calcined body of the present invention is more preferably 5.0 wt% to 15.0 wt% in terms of indium. If the indium content is less than 2.0 wt%, the zirconia sintered body cannot be imparted with sufficient translucency. On the other hand, if the indium content exceeds 20.0 wt%, the zirconia sintered body cannot be imparted with sufficient translucency. In the present invention, the amount of indium in the translucency improving liquid for dental zirconia calcined body is most important.

[0014] The indium compound can be any known indium compound that dissolves in a solvent without any limitations. Specifically, the indium compound used in the present invention includes indium oxide, halide, nitrate, sulfate, and organic acid salt. Specific examples include indium oxide, indium nitrate, indium chloride, and indium sulfate. Indium nitrate is preferably used because it is easily available and easily dissolves in a solvent.

[0015] The solvent used in the translucency improving liquid for dental zirconia calcined body of the present invention may be any solvent, but water, organic solvents, etc. can be used. Water, alcohol, or a mixture thereof is particularly preferred because of their ease of availability and handling. A specific example of alcohol is ethanol. The solvent is the base material of the translucency improving liquid for dental zirconia calcined body, and the blending amount is the remainder of the blending components in the translucency improving liquid for dental zirconia calcined body.

[0016] The translucency improving liquid for dental zirconia calcined body of the present invention may contain a precipitant for the purpose of suppressing segregation in the zirconia cutting body for dental cutting. Examples of precipitants include urea and hexamethylenetetramine, but urea is preferred because of its easy availability. There are no particular limitations on the concentration of the precipitant, but it is preferably 5 wt% to 40 wt%.

[0017] The translucency improving liquid for dental zirconia calcined body of the present invention may contain metals other than indium. Specific examples include yttrium, which acts as a stabilizer in zirconia, and erbium, iron, cobalt, and the like, which act as colorants. There are no particular limitations on the concentrations of metals other than indium, but it is preferable that yttrium be 4 wt% or less, and that the metals acting as colorants be 2 wt% or less, and more preferably that the total of the metals acting as colorants be 2 wt% or less. If the yttrium concentration exceeds 4 wt%, the translucency tends to decrease. If the ion concentration of the metals acting as colorants exceeds 2 wt%, it becomes difficult to reproduce the color tone of natural teeth.

[0018] The translucency improving liquid for dental zirconia calcined body of the present invention may contain a thickener. Specific examples include polyols and glycol ethers. There are no particular restrictions on the concentration of the thickener, but it is preferably 5 wt% or less, and more preferably 0.001 wt% to 5 wt%. A thickener concentration exceeding 5 wt% is not preferred because it takes too long for the translucency improving liquid to penetrate.

[0019] The translucency improving liquid for dental zirconia calcined body of the present invention may contain a dye to enhance visibility. This dye is preferably one that is decomposed and removed in the subsequent sintering step. This dye is preferably an organic dye, and specific examples include rhodamine and methylene blue. There are no particular limitations on the concentration of the dye, but a concentration of 0.01 wt% to 1 wt% is preferred.

[0020] The method for preparing the translucency improving liquid for dental zirconia calcined body in the present invention is not particularly limited, and any preparation method can be used without any problem as long as a metal compound is dissolved in a solvent.

[0021] The method of using the translucency improving liquid for dental zirconia calcined body in the present invention is not particularly limited as long as it can be permeated into any desired portion of the zirconia calcined body to support indium in that portion. Specifically, the zirconia calcined body may be partially or entirely immersed in the translucency improving liquid for dental zirconia calcined body, or the translucency improving liquid may be applied to the zirconia calcined body using a brush or the like. Specific portions to be applied include the occlusal surface or incisal side of a dental zirconia calcined body having a cut tooth shape.

[0022] The specific atmosphere in which the translucency improving liquid is permeated into the dental zirconia calcined body is not particularly limited, and any of an atmospheric pressure atmosphere, a reduced pressure atmosphere, and a pressurized atmosphere is acceptable. From the viewpoint of shortening the production time, placing the surrounding environment under a reduced pressure atmosphere or a pressurized atmosphere is preferable because it promotes the permeation of the translucency improving liquid. Furthermore, repeating the operation of returning the pressure to atmospheric pressure after a reduced pressure operation (reduced pressure / atmospheric pressure operation) or the operation of returning the pressure to atmospheric pressure after a pressurized operation (pressurized / atmospheric pressure operation) multiple times is effective in shortening the time required for the step of permeating the translucency improving liquid into spaces inside the dental zirconia calcined body that communicate with the outside of the dental zirconia calcined body.

[0023] The time for immersing the dental zirconia calcined body in the translucency improving liquid is not necessarily determined, but can be adjusted appropriately depending on the relative density and compact size of the dental zirconia calcined body, the penetration level of the translucency improving liquid, the immersion method, etc. For example, the time for immersion is usually 1 to 120 hours, for immersion under reduced pressure it is usually 0.5 to 12 hours, and for contact under pressure it is usually 0.2 to 6 hours.

[0024] There is no limitation on the shape of the zirconia calcined body to be impregnated with the translucency improving liquid for a dental zirconia calcined body of the present invention. It may be in the shape of a disk or block before cutting, or in the shape of an inlay, laminate, crown, bridge, or the like after cutting. Furthermore, in order to obtain a more aesthetic prosthetic device by applying the translucency improving liquid of the present invention, it is more preferable to use a dental zirconia calcined body in the shape of a block or disk having a multilayer structure.

[0025] The relative density of the zirconia calcined body to be impregnated with the translucency improving liquid for dental zirconia calcined body in the present invention is preferably 50 to 70%. A relative density of less than 50% is not preferred because desirable strength and translucency cannot be obtained when the workpiece is sintered. On the other hand, a relative density of more than 70% is not preferred because the translucency improving liquid does not sufficiently penetrate the zirconia calcined body, and desirable translucency cannot be obtained when the zirconia calcined body is sintered. In this specification, the relative density of the zirconia calcined body refers to the apparent density of the zirconia calcined body, which is a semi-sintered body, when the density of a fully sintered body is taken as 100%.

[0026] The specific surface area of ​​the zirconia calcined body to be impregnated with the translucency improving liquid for dental zirconia calcined body in the present invention is 0.5 to 10 m 2 / g. The specific surface area is preferably 0.5m 2 / g or less, and 10m 2 If it exceeds 1 / g, desirable translucency cannot be obtained when the zirconia calcined body is sintered, which is not preferable.

[0027] The zirconia calcined body impregnated with the translucency improving liquid for dental zirconia calcined body of the present invention is preferably dried thereafter. There are no particular limitations on the drying method, but drying in a dryer at 80 to 120°C is preferred because it allows drying in a short time.

[0028] When the light-transmittance improving liquid of the present invention is used as a coating liquid, it is preferable that the light-transmittance improving liquid is produced by mixing all of the components, and is preferably a liquid with fluidity. The light-transmittance improving liquid may be in any state, and examples include a state in which all of the components are uniformly dissolved together, a state in which the liquid is separated into multiple layers, or a state in which a specific component is separated and precipitated. However, there is no particular problem as long as the liquid can be made uniform overall by shaking or other procedures before use. Among these, from the viewpoint of penetration of the light-transmittance improving liquid of the present invention after application to a dental zirconia calcined body, it is preferable that the light-transmittance improving liquid be in a liquid with fluidity and low viscosity in which all of the components are uniformly dissolved together, as described above.

[0029] Furthermore, the method of applying the translucency improving liquid of the present invention to a dental zirconia calcined body is not particularly limited as long as it can be applied uniformly to the surface of the dental zirconia calcined body, and any application method, such as application with a brush, spraying with a spray or the like, or dropping with a pipette, etc., is not particularly limited. Among these, application with a brush or the like is preferred because it can be applied uniformly only to the surface of the dental zirconia calcined body.

[0030] When the translucency improving liquid of the present invention is used as a coating liquid, it is preferable to coat only the surface layer of a dental zirconia calcined body with the translucency improving liquid. In this way, the transparency of only the surface layer can be improved assuming a dental crown shape. For example, by coating only the enamel part of a dental crown shape, the cervical part can be maintained in an opaque state.

[0031] In this manner, a calcined zirconia body to which indium has been added using the translucency improving liquid of the present invention is obtained.

[0032] There are no particular limitations on the method for final firing (sintering) the obtained zirconia calcined body, but a simple and preferred method is firing at normal pressure. There are no particular limitations on the firing temperature, but 1450 to 1600°C is preferred, and 1500 to 1600°C is particularly preferred. There are no particular limitations on the retention time at the firing temperature, but 1 minute to 12 hours is preferred, and 2 to 4 hours is particularly preferred. There are no particular limitations on the temperature rise rate, but 1 to 400°C / min is preferred, and more preferably 3 to 100°C / h is particularly preferred. [Example]

[0033] [Adjustment of the translucency improving liquid] The composition of the translucency improving liquid shown in Table 1 was mixed and then stirred for 1 hour to prepare the liquid. The total amount of each component in Table 1 does not equal 100% because the weights of nitrate ions, chloride ions, etc. contained in the indium source and colorant source are not added. [Table 1]

[0034] [Preparation of zirconia calcined body] Zirconia powder containing 5.5 mol% dissolved yttria (Zpex SMILE: manufactured by Tosoh Corporation, containing 0.05 wt% alumina) was filled into a mold (φ100 mm) and pressed (surface pressure: 50 MPa) to obtain a green body. The green body was then subjected to CIP (maximum load pressure: 200 MPa, load pressure after release: 0 MPa, holding time: 1 minute, number of repetitions: 10). It was then calcined in an electric furnace (1000°C, 30 minutes) to produce a zirconia pre-sintered body.

[0035] [Sintering conditions] The zirconia calcined body was fired in a firing furnace (firing temperature: 1550°C, temperature rise rate: 5°C / min, holding time: 120 min) to produce a zirconia sintered body.

[0036] [Translucency evaluation] Test specimens for evaluating translucency were prepared by cutting calcined zirconia bodies into round plates (φ14 mm × 1.6 mm). Each test specimen was sintered in a firing furnace. The thickness of each test specimen (1.0 mm) was then adjusted using a surface grinder. Translucency was evaluated by measuring the contrast ratio. The contrast ratio was measured using a spectrophotometer (manufactured by Konica Minolta). The Y value measured with a white board placed under each test specimen was defined as Yw, and the Y value measured with a black board placed under the test specimen was defined as Yb. The contrast ratio was calculated using the following formula. The closer the contrast ratio is to 0, the more translucent the material is; the closer the contrast ratio is to 1, the more opaque the material is. Contrast ratio = (Yb / Yw) (formula) Furthermore, the degree of improvement in light transmittance was calculated using the following formula. Translucency improvement rate = (1 - (contrast ratio of test piece) / (contrast ratio of reference piece)) x 100 The reference products were sintered bodies that did not use any light-transmittance improving liquid (Comparative Example 8 in Examples 1 to 12, Comparative Example 9 in Example 13, and Comparative Example 7 in Example 14). The degree of improvement in the translucency of each test specimen was evaluated using the following ABC score. Translucency improvement degree≧5:A 5>Translucency improvement degree≧3:B 3>Translucency improvement degree: C In the case of A, it has a high ability to improve light transmittance. In the case of B, it has a certain degree of ability to improve light transmittance. In case C, the ability to improve the light transmittance is low or not at all.

[0037] Example 1: A zirconia calcined body was machined into a round plate (φ14 mm × 1.6 mm). The obtained test specimen was immersed in Solution 1 (room temperature, 1.5 hours). The test specimen was then removed from Solution 1, and the solution adhering to the surface was wiped off, followed by drying in a dryer (120°C, 1 hour). The dried test specimen was fired in a firing furnace (firing temperature: 1550°C, heating rate: 5°C / min, holding time: 120 minutes) to produce a zirconia sintered body.

[0038] Example 2: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 2 was used instead of Solution 1. Example 3: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 3 was used instead of Solution 1. Example 4: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 4 was used instead of Solution 1. Example 5: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 5 was used instead of Solution 1. Example 6: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 6 was used instead of Solution 1. Example 7: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 7 was used instead of Solution 1. Example 8: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 8 was used instead of Solution 1. Example 9: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 9 was used instead of Solution 1. Example 10: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 10 was used instead of Solution 1. Example 11: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 11 was used instead of Solution 1. Example 12: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 12 was used instead of Solution 1. Example 13: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 13 was used instead of Solution 1.

[0039] Example 14: A test specimen for a maxillary left central incisor (single crown) was prepared by cutting a zirconia calcined body. Solution 3 was applied to the resulting test specimen five times with a brush. The first application was to approximately half of the total length from the incisal edge, the second application to approximately one-third of the total length, the third application to approximately one-quarter of the total length, and the fourth and fifth applications to one-fifth of the total length. The specimen was then dried in a dryer (120°C, 1 hour) and fired in a firing furnace (firing temperature: 1550°C, heating rate: 5°C / min, holding time: 120 minutes) to obtain a restoration for a maxillary left central incisor (single crown).

[0040] Comparative Example 1: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 14 was used instead of Solution 1. Comparative Example 2: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 15 was used instead of Solution 1. Comparative Example 3: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 16 was used instead of Solution 1. Comparative Example 4: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 17 was used instead of Solution 1. Comparative Example 5: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 18 was used instead of Solution 1. Comparative Example 6: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 19 was used instead of Solution 1. Comparative Example 7: A zirconia sintered body was produced in the same manner as in Example 1, except that Solution 20 was used instead of Solution 1. Comparative Example 8: A zirconia sintered body was produced in the same manner as in Example 1, except that immersion in the solution was not performed. Comparative Example 9: A zirconia sintered body was produced in the same manner as in Example 13, except that Solution 21 was used instead of Solution 13. Comparative Example 10: A restoration in the shape of a single crown for the maxillary left central incisor was prepared in the same manner as in Example 14, except that no solution was applied.

[0041] Table 2 shows the results of the property tests on the zirconia workpieces for dental cutting produced in the examples and comparative examples.

[0042] [Table 2]

[0043] In Examples 1 to 13, a solution with an indium concentration of 2.0 to 20.0 wt % was used, and therefore the translucency was sufficiently improved, and translucency similar to that of natural teeth was exhibited.

[0044] In Comparative Examples 1 to 7 and 9, solutions with indium concentrations of less than 2.0 wt% or more than 20.0 wt% were used, so the translucency was not sufficiently improved and translucency similar to that of natural teeth was not obtained.

[0045] The prosthesis of Example 14 had a gradually improved translucency from the middle part of the prosthesis toward the incisal edge, and had an appearance similar to that of natural teeth.

[0046] The prosthesis of Comparative Example 10 had the same insufficient translucency throughout the entire prosthesis, and had an appearance different from that of natural teeth. [Industrial Applicability]

[0047] The present invention relates to a solution for improving the translucency of zirconia dental articles and a method for using the same, and is a technology that can be used in the dental field.

Claims

1. A translucency improving liquid for a dental zirconia calcined body, comprising: a solvent and an indium compound; A translucency improving solution for a dental zirconia calcined body, comprising an indium compound in an amount of 2.0 wt % to 20.0 wt % in terms of indium relative to the total amount of the solution.

2. 2. The translucency improver for dental zirconia calcined bodies according to claim 1, wherein the solvent is water, alcohol, or a mixture thereof.

3. 3. The translucency improver for a dental zirconia calcined body according to claim 1, further comprising a precipitating agent.

4. A method for using the translucency improving liquid for a dental zirconia calcined body according to any one of claims 1 to 3, comprising applying the translucency improving liquid to and / or impregnating a dental zirconia calcined body with the translucency improving liquid.

5. A method for using the translucency improver for a dental zirconia calcined body according to any one of claims 1 to 3, comprising applying the translucency improver to an occlusal surface or an incisal side of a dental zirconia calcined body having a cut tooth shape.

6. 6. A method for using the translucency improving liquid for a dental zirconia calcined body according to claim 5, wherein the tooth-shaped dental zirconia calcined body is in the form of an inlay, a laminate, a crown or a bridge.

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