DE102015103439A1 - Method for increasing the translucency of ceramic dentures - Google Patents

Abstract

The invention relates to a method for increasing the translucency of ceramic dental prostheses, wherein a zirconia-containing porous ceramic is provided, wherein a yttrium-containing solution is applied locally to the ceramic, and wherein the solution is ionic or complex-containing. The invention allows a local increase and thus more flexible adjustment of the translucency of ceramic bodies.

Description

The invention relates to a method for increasing the translucency of ceramic dentures. In particular, the invention relates to a method for increasing the translucency of zirconia-based dental ceramics.

Ceramics are used extensively in dentistry because of their aesthetic properties. Since the introduction of the CAD / CAM technique, the materials used to make ceramic dental prostheses are being further developed with regard to their strength, processability and aesthetics.

One of the essential steps here is the processing of partially sintered ceramics based on zirconium oxide. This material system has meanwhile become established as one of the most important materials for the production of crowns and bridges.

The zirconia, which is used for practically all dental applications, is stabilized in a proportion of 4-6% by weight of Y ₂ O ₃ (Y-TZP). This gives the material an outstanding strength of up to 1500 MPa. However, the material has a pure white color and can not be used without veneering with a less solid material.

For this reason, several methods for coloring dental ceramics have been developed. From the DE 42 07 179 A1 is a method for coloring dental ceramics known in which the raw material is colored. From the DE 199 04 522 C5 For example, a method is known which permits coloring of the presintered ceramic material.

The goal in prosthodontics is the most lifelike reproduction of a natural tooth. A typical feature of a tooth is the change in color over the height of the tooth. This means that the tooth becomes brighter from the cervical edge to the incisal edge, that is, has less color saturation. In dental prosthetics, the color gradient is imaged by stacking different colored layers of Y-TZP in the blank.

In addition to color, another characteristic of natural teeth is that the teeth have high transparency in the area of the cutting edge. This can not be achieved even with colored zirconia. In practice, the higher-transparent parts of the tooth are made more transparent by manual layers of ceramic layers of different translucency, which is associated with a considerable effort.

From the US 2013/0221554 A1 For example, a method is known in which zirconia ceramics of different translucency are layered on top of one another in order to obtain the desired course of the translucency. The course is achieved by a gradual increase in the yttria content. The coloring must then also be done by layering or by coloring the milling body.

It is desirable to increase the translucency in the dental restoration, in principle, where a corresponding translucency course is to be expected even in the natural tooth. With the known methods one is limited production engineering.

Based on the known prior art, the present invention seeks to provide a method for increasing the translucency of ceramic dentures, which allows a more flexible influence on the translucency.

• – dass eine zirkonoxidhaltige poröse Keramik zur Verfügung gestellt wird, und
• – dass auf die Keramik eine yttriumhaltige Lösung lokal aufgebracht wird,
• – wobei die Lösung ionisch oder komplexhaltig ist.

To solve this problem, the method mentioned above is characterized according to the invention by

• - That a zirconia-containing porous ceramic is provided, and
• - that a yttrium-containing solution is applied locally to the ceramic,
• - The solution is ionic or complex.

It is generally known that increasing the yttrium content in the zirconia ceramics increases the translucency. As described above, in the prior art, the yttrium content is determined in the production of the raw material. Here, yttrium and zirconium oxide are precipitated together from the solution (co-precipitation). Thereafter, the proportion of yttrium oxide is no longer changeable. For applications where a certain Y ₂ O ₃ content is required, such. B. lambda probes, this must therefore already be set in the preparation of the Ausgansmaterial. The same applies to the production of dentures.

By contrast, according to the invention, it is possible to change the raw material in its yttrium content at a later time. In this case, the solution is applied locally to the ceramic. The inventive method is compared to conventional solutions much more flexible, since the local order any course of translucency can be created. In particular, the invention allows that the translucency in the overall restoration can be increased even after milling, as proposed in development of the invention. For this purpose, the ceramic is first milled in the form and then applied the solution locally. This has the advantage that the translucency curve can be defined even more precisely.

The solution according to the invention consists in preparing a solution of yttrium ions in a solvent. This is applied locally. By a chemical reaction, the Y ^{3+ transforms} into insoluble Y ₂ O ₃ and is incorporated into the interstitial sites of the ZrO ₂ and achieves the desired effect of increasing the translucency after firing to final density.

For the application of the solution, it is considered preferable if the ceramic is dipped in the solution. The degree of translucency depends on the duration of exposure (immersion time).

Preferably, the exposure time is between 5 seconds and 10 minutes.

Alternatively, it is suggested that the solution be applied with a brush or by spraying. The application by means of a brush allows a fine tuning of the translucency. Spraying is considered to be advantageous in larger-scale courses.

The solution is expediently prepared from the salts of yttrium, the dissolved salts containing yttrium chlorides, yttrium acetates, alkoxides of yttrium or oxo complexes of yttrium.

The concentration of yttrium ions in the solution is of particular importance. In this connection, it is proposed that the concentration of yttrium ions is between 1 mol / liter and 7 mol / liter, preferably between 3 mol / liter and 6.5 mol / liter. Such a concentration has proved to be particularly advantageous.

As water-soluble compounds of yttrium to provide advantageous to salts or complexes of the counter ions Cl ^-, Br ^-, J ^-, SO ₄ ^2-, SO ₃ ^2-, OCN ^-, SCN ^- or, in particular NO ₂ ^- or NO ₃ ^- to.

In the following, the invention is explained by an example, without the example being intended to limit the invention.

Yttrium nitrate is dissolved in deionized water, for example by means of a magnetic stirrer. Other solutions are conceivable, such. B. alcoholic solutions. In addition to yttrium nitrate, yttrium nitride has also provided excellent solubility results. The high solubility also has a positive influence on the translucency.

Y-TZP white compacts having a density of 3.09 g / cm ³ and dimensions of 20 × 20 × 1.5 mm were immersed for 30 minutes each in solutions of various Y (NO ₃ ) ₃ concentrations and then at 120 ° C. for 10 minutes dried.

The sintering took place up to 1550 ° C with a holding time of 2 hours. Subsequently, the samples were ground on one side to a thickness of 0.8 mm with a grain of D126 and burned in the glaze oven. Then, the translucency of the samples was measured. In addition, the Y ₂ O ₃ content was measured with an RFA. This was done on the as-fired and on the ground side so that it could be compared how homogeneous the Y ₂ O ₃ content is in the sample. Part # Concentration mol / l Add yttrium nitrate g / l Thickness mm Translucency% Content Y ₂ O ₃ middle mol% Content Y ₂ O ₃ surface mol% 1.1 0 0 0.8 34.82 3.67 3.61 1.2 0 0 0.8 34.92 3.60 3.61 2.1 2.09 800 0.8 36.86 5.08 6.10 2.2 2.09 800 0.8 36.83 5.00 5.76 3.1 3.66 1400 0.8 37.48 5.59 6.31 3.2 3.66 1400 0.8 37.91 5.84 6.56 4.1 4.7 1800 0.8 38.10 6.08 6.54 4.2 4.7 1800 0.6 41.12 6.32 6.02 5.1 6.53 2500 0.7 39.36 6.52 6.63 5.2 6.53 2500 0.8 37.77 6.52 6.75

As a result, the translucency can be controlled with the concentration of the yttrium-containing solution.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 4207179 A1 [0005]
• DE 19904522 C5 [0005]
• US 2013/0221554 A1 [0008]

Claims (7)

Method for increasing the translucency of ceramic dentures, wherein A zirconia-containing porous ceramic is provided, - On the ceramic, a yttrium-containing solution is applied locally, and wherein - The solution is ionic or complex. A method according to claim 1, characterized in that the ceramic is immersed in the solution. A method according to claim 2, characterized in that the exposure time is between 5 seconds and 10 minutes. A method according to claim 1, characterized in that the solution is applied with a brush or by spraying. Method according to one of claims 1 to 4, characterized in that the solution is prepared from the salts of yttrium and that the dissolved salts yttrium chlorides, yttrium acetates, alkoxides of yttrium or oxo complexes of yttrium. Method according to one of claims 1 to 5, characterized in that the concentration of the yttrium ions is between 1 mol / liter and 7 mol / liter, preferably between 3 mol / liter and 6.5 mol / liter. Method according to one of claims 1 to 4, characterized in that the solution is prepared from the salts of yttrium and that the counterions Cl ^- , Br ^- , J ^- , SO ₄ ^2- , SO ₃ ^2- , OCN ^- , SCN ^- or in particular NO ₂ ^- or NO ₃ ^- , are.