Method to manufacture a colored blank, and blank

Patent metadata

Field	Value
Publication number	US-10441391-B2
Application number	US-201715464316-A
Country	US
Kind code	B2
Filing date	Mar 20, 2017
Priority date	Mar 23, 2016
Publication date	Oct 15, 2019
Grant date	Oct 15, 2019

Abstract

The invention relates to a method for manufacturing a colored blank, which contains zirconium dioxide and is intended for the manufacture of a dental restoration, whereby raw materials in powder form, at least some of which contain one coloring substance each, are mixed with, zirconium dioxide as the main ingredient, the resulting mixture is pressed and subsequently subjected to at least one thermal treatment. To generate the desired fluorescence, it is intended that in the raw materials in powder form one uses as coloring substances at least terbium, erbium, cobalt, as well as one substance that generates a fluorescence effect in the dental restoration, however not iron, aside from naturally occurring impurities.

First claim

The invention claimed is:

1. A method for manufacturing a colored blank comprising zirconium dioxide that is intended for the production of a dental restoration, the method comprising the steps of:
introducing into a mold a layer of a first ceramic material, which includes at least one coloring element, with zirconium dioxide as the main constitute to form a first mixture, wherein a first open cavity is formed in the layer;
introducing at least into the first open cavity a second ceramic material define a second layer, which includes a second mixture with a composition that is different from that of the first mixture;
pressing the first mixture and the second mixture, and subsequently subject the pressed first and second mixtures to at least one thermal treatment,
wherein the at least one coloring element in the raw materials in powder form is selected from the group consisting of terbium, erbium, cobalt, one element that generates a fluorescent effect in the dental restoration, and mixtures thereof,
wherein iron, apart from natural impurities, is not present.

2. The method of claim 1 , wherein bismuth is used as the element that generates the fluorescent effect.

3. The method of claim 1 , wherein disregarding naturally occurring impurities, the raw materials include at least one of the following:
a first raw material in powder form that includes bismuth as the element that generates the fluorescent effect;
a second raw material in powder form that includes exclusively terbium, or terbium and praseodymium;
a third raw material in powder form that includes exclusively erbium;
a fourth raw material in powder form that includes exclusively cobalt, or cobalt and manganese, and/or cerium; and
combination thereof.

4. The method of claim 1 , wherein one of the raw materials in powder form is free of coloring elements, apart from natural impurities.

5. The method of claim 1 , wherein raw materials in powder form includes yttrium-stabilized zirconium dioxide of the following composition:
HfO 2 <3.0% by wt;
Al 2 O 3 <0.3% by wt;
Unavoidable impurities due to technical limitations ≤0.2% by wt;
Y 2 O 3 4.5 to 9.5% by wt;
ZrO 2 =100%−(Y 2 O 3 +Al 2 O 3 +HfO 2 +unavoidable impurities) % by wt.

6. The method of claim 1 , wherein after introduction of the second ceramic material, a second open cavity is created in the mold.

7. The method of claim 6 , wherein into the second open cavity is filled a third ceramic material, which possesses a composition that is different from those of the first and/or second ceramic material.

8. The method of claim 1 , wherein in the layer formed of the first ceramic material are formed several first open cavities and into these is filled the second ceramic material.

9. The method of claim 8 , wherein at least some of the several open first cavities possess differing inside geometries.

10. The method of claim 1 , wherein after sintering to full density, the second ceramic material possesses a thermal expansion coefficient that is 0.2 to 0.8 μm/m*K greater than that of the first ceramic material.

11. The method of claim 1 , wherein the interior geometry of the first open cavity is geometrically matched to the shape of a dental jaw region that is to be provided with a restoration or to that of an abutment originating from a jaw region.

12. The method of claim 1 , wherein when working the dental restoration out of the blank, a dentine region of the dental restoration is at least partially composed of the second ceramic material and an incisal region of the first ceramic material.

13. The method of claim 1 , wherein the yttrium oxide content in the first ceramic material is 7.0% by weight to 9.5% by weight; and/or the yttrium content in the second and/or third ceramic material is 4.5% by weight to 7.0% by weight, whereby the yttrium oxide content in the first ceramic material is higher than that of the second or third material.

14. The method of claim 1 , wherein in the first ceramic material or the second ceramic material, the quotient of the tetragonal crystal phase and the cubic crystal phase of the zirconium dioxide after pre-sintering is ≥1.

15. A method for the manufacture of a blank of a ceramic material, whereby at least two layers are introduced by filling into a mold ceramic material, which includes mixtures that were created in accordance with claim 1 and possess different compositions, and that after introduction of the layers, these are pressed and subsequently sintered, after introduction of a first layer comprising of a first mixture, the surface of this layer is structured in such a way that the surface of the first layer, viewed along the surface, possesses regions of different heights, and subsequently a second layer comprising of a mixture with a composition different from that of the first mixture is filled into the mold, or in that after introduction of the first layer, a further layer is filled on top of it into the mold, which includes of a mixture that is different from that of the first layer, in that the material of the first layer is intermixed with the material of the further layers to form an intermediate layer, and that subsequently the second layer is filled into the mold.

16. The method of claim 15 , wherein the surface of the first layer is being structured in a way so that depressions and elevations are created whereby the latter confine the former.

17. The method of claim 15 , wherein in a top view of the surface the created structure has an annular pattern, which comprises the depressions and the elevations bordering them.

18. The method of claim 1 , wherein a structure is created by an element, which moves-relative to the first layer, and which structures a surface region of the first layer with a segment that is embodied with a wave-like, comb-like or serrated shape.

19. The method of claim 18 , wherein the structure is created by a pressure element that acts along a direction perpendicular to the surface region of the first layer.

20. The method of claim 19 , wherein the pressure element imprints into the surface region of the first layer elevations that extend concentrically or in parallel, and depressions extending in between the elevations.

21. The method of claim 15 , wherein the structure is formed in such a way that the volume of the elevations is equal or approximately equal to the volume of the depressions.

22. The method of claim 15 , wherein the material of the mixture of the additional layer is intermixed with the material of the mixture of the first layer downward from the free surface of the additional layer along a height that corresponds to twice or approximately twice the height of the additional layer.

23. The method of claim 22 , wherein the mixture used for the additional layer is identical to that of the second layer.

24. The method of claim 1 , wherein that contacting regions of the first layer and the second layer are mixed over a height that corresponds to ⅕ H to ¼ H, where H is the total height H of the first and second layer.

25. The method of claim 1 , wherein that the first layer in an unstructured state possesses a height that corresponds to half or approximately half the height of the total height H of the first and second layer.

26. The method of claim 1 , wherein the first and second ceramic mixtures used for the first layer and the second layer are such that the quotient of the tetragonal crysta

Assignees

• Dentsply Sirona Inc

Inventors

• Volkl Lothar
• Fecher Stefan
• Kutzner Martin
• Oefner Tanja

Classifications

• A61C13/09

  {Composite teeth, e.g. front and back section (A61C13/0835, A61C13/1023 take precedence)}; Multilayer teeth · CPC title

• A61K6/824

  comprising transition metal oxides · CPC title

• A61K6/15

  Compositions characterised by their physical properties · CPC title

• A61K6/78

  Pigments · CPC title

• A61K6/822

  comprising rare earth metal oxides · CPC title