METHOD TO MANUFACTURE A COLORED BLANK, AND BLANK

• US 20170273764A1
• Filed: 03/20/2017
• Published: 09/28/2017
• Est. Priority Date: 03/23/2016
• Status: Active Grant

• Current Assignee: Dentsply Sirona INC. (Astrazeneca PLC)
• Original Assignee: Dentsply Sirona INC. (Astrazeneca PLC)
• Inventors: VOLKL, Lothar, FECHER, Stefan, KUTZNER, Martin, OEFNER, Tanja
• Granted Patent: US 10,441,391 B2
• Time in Patent Office: Days
• CPC Class Codes: A61C 13/0022 Blanks or green, unfinished dental restoration parts
• CPC Class Codes: A61C 13/082 Cosmetic aspects, e.g. inlays; Determination of the colour A61C19/10 takes precedence
• CPC Class Codes: A61C 13/083 Porcelain or ceramic teeth A61C13/081 takes precedence; preparations A61K6/80
• CPC Class Codes: A61C 13/09 Composite teeth, e.g. front and back section A61C13/0835, A61C13/1023 take precedence; Multilayer teeth
• CPC Class Codes: A61K 6/15 Compositions characterised by their physical properties
• CPC Class Codes: A61K 6/78 Pigments
• CPC Class Codes: A61K 6/818 comprising zirconium oxide
• CPC Class Codes: A61K 6/822 comprising rare earth metal oxides
• CPC Class Codes: A61K 6/824 comprising transition metal oxides
• CPC Class Codes: A61K 6/84 comprising metals or alloys
• CPC Class Codes: B32B 18/00 Layered products essentially comprising ceramics, e.g. refractory products
• CPC Class Codes: C04B 2235/3224 Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3244 Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3275 Cobalt oxides, cobaltates or cobaltites or oxide forming salts thereof, e.g. bismuth cobaltate, zinc cobaltite
• CPC Class Codes: C04B 2235/40 Metallic constituents or additives not added as binding phase
• CPC Class Codes: C04B 2235/608 Green bodies or pre-forms with well-defined density
• CPC Class Codes: C04B 2235/612 Machining
• CPC Class Codes: C04B 2235/72 Products characterised by the absence or the low content of specific components, e.g. alkali metal free alumina ceramics
• CPC Class Codes: C04B 2235/728 Silicon content
• CPC Class Codes: C04B 2235/75 : Products with a concentration gradient
• CPC Class Codes: C04B 2235/945 : Products containing grooves, cuts, recesses or protusions
• CPC Class Codes: C04B 2235/96 : Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
• CPC Class Codes: C04B 2235/9607 : Thermal properties, e.g. thermal expansion coefficient
• CPC Class Codes: C04B 2235/9646 : Optical properties
• CPC Class Codes: C04B 2235/9653 : Translucent or transparent ceramics other than alumina
• CPC Class Codes: C04B 2235/9661 : Colour
• CPC Class Codes: C04B 2237/348 : Zirconia, hafnia, zirconates or hafnates
• CPC Class Codes: C04B 35/48 : based on zirconium or hafnium oxides, zirconates, zircon or hafnates
• CPC Class Codes: C04B 35/486 : Fine ceramics

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.

Claims

1. A method for manufacturing a colored blank comprising zirconium dioxide that is intended for the production of a dental restoration, whereby raw materials in powder from, at least several of which contain one coloring element each, are mixed with zirconium dioxide as the main constituent, the resulting mixture is pressed, and subsequently subjected to at least one thermal treatment, wherein as the coloring elements in the raw materials in powder form one uses at least terbium, erbium, cobalt, as well as one element that generates a fluorescent effect in the dental restoration, while 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, a first raw material in powder form contains bismuth as the element that generates the fluorescent effect and/or a second raw material in powder from contains exclusively terbium or terbium and praseodymium and/or a third, raw material in powder form contains exclusively erbium and/or a fourth raw material in powder form contains exclusively cobalt or cobalt and manganese and/or cerium.

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 contains yttrium-stabilized zirconium dioxide of the following composition:

HfO₂<

3.0

Al₂O₃<

0.3

Unavoidable impurities due to technical limitations ≦

0.2 (such as SiO₂, Fe₂O₃, Na₂O)

Y₂O₃ 4.5 to 9.5

ZrO₂=100%−

(Y₂O₃+Al₂O₃+HfO₂+unavoidable impurities)

in particular

HfO₂<

3.0

Al₂O₃<

0.3

Unavoidable impurities due to technical limitations ≦

0.2 (such as SiO₂, Fe₂O₃, Na₂O)

Y₂O₃ 4.5 to 9.5

ZrO₂=100%−

(Y₂O₃+Al₂O₃+HfO₂+unavoidable impurities)

or

HfO₂<

3.0

Al₂O₃<

0.3

Unavoidable impurities due to technical limitations ≦

0.2 (such as SiO₂, Fe₂O₃, Na₂O)

Y₂O₃ 4.5 to 9.5

ZrO₂=100%−

(Y₂O₃+Al₂O₃+HfO₂+unavoidable impurities)

6. The method for manufacturing a blank (28, 48) of claim 1, wherein introduced into a mold (10) is a layer of a first ceramic material (14), which consists of a first mixture, in that a first open cavity (18) is formed in the layer, in that at least into the first open cavity is introduced a second ceramic material (20), which consists a second mixture with a composition that is different from that of the first mixture, and in that the materials are together subjected to<

pressing and a subsequent thermal treatment.

7. The method of claim 1, wherein after introduction of the second ceramic material (18), a second open cavity (26, 36) is created in it.

8. The method of claim 1, wherein into the second open cavity (36) is filled a third ceramic material (38), which possesses a composition that is different from those of the first and/or second ceramic material (20).

9. The method of claim 1, wherein in the layer formed of the first ceramic material (14) are formed several first open cavities (18) and into these is filled a ceramic material (18) in particular the second ceramic material.

10. The method of claim 1, wherein at least some of the several open first cavities (18) possess differing inside geometries.

11. The method of claim 1, wherein as the second ceramic material (20) one uses a material that after the sintering, to full density possesses a thermal expansion coefficient that is 0.2 to 0.8 μ

m/m*K greater than that of the first ceramic material (14).

12. The method of claim 1, wherein the interior geometry of the first open cavity (18) is geometrically matched'"'"'to the shape of a dental jaw region that is to be provided with a restoration, such as a tooth stump, or to that of an abutment originating from a jaw region.

13. The method of claim 1, wherein when working the dental restoration out of the blank (28, 48), the dentine region of the dental restoration is at least partially composed of the second ceramic material (20) and the incisal region of the first ceramic material (14),

14. The method of claim 1, wherein as the first and/or second ceramic material (14, 20) one choses the materials so that the yttrium oxide content in the first material is 7.0% by weight to 9.5% by weight and/or the content in the second and/or third 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.

15. The method of claim 1, wherein in the chosen ceramic materials the quotient of the tetragonal crystal phase and the cubic crystal phase of the zirconium dioxide in the materials (14, 20) after pre-sintering is 1.

16. A method for the manufacture of a blank (133) of a ceramic material, whereby at least two layers (114, 124) are introduced by filling into a mold (110) 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 (114) comprising of a first mixture, the surface of this layer is structured in such a way that the surface (118) of the first layer, viewed along the surface, possesses regions of different heights, and subsequently a second layer (124) 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 (214), a further layer (227) is filled on top of it into the mold (110), which consists 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 (228), and that subsequently the second layer (224) is filled into the mold (110).

17. The method of claim 16, wherein the surface (118) of the first layer (114) is being structured in a way so that depressions and elevations are created whereby the latter confine the former.

18. The method of claim 16, wherein in a top view of the surface (118) the created structure has an annular pattern, which comprises the depressions and the elevations bordering them.

19. The method of claim 1, wherein the structure is created by an element (116), which moves, in particular rotates, relative to the first layer (114), and which in particular structures the surface region of the first layer (114) with a segment that is embodied with a wave-like, comb-like or serrated shape.

20. The method of claim 1, wherein the structure is created by a pressure element that acts along a direction perpendicular to the surface (118) of the first layer (114).

21. The method of claim 1, wherein the employed pressure element imprints into the surface (118) of the first layer (114) elevations that extend concentrically or in parallel, and depressions extending in between the elevations.

22. The method of claim 16, 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.

23. The method of claim 16, wherein the material of the mixture of the additional layer (227) is intermixed with the material of the mixture of the first layer (214) 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.

24. The method of claim 23, wherein the mixture used for the additional layer (227) is identical to that of the second layer (124, 224).

25. The method of claim 1, wherein that the contacting regions of the first layer (114) and the second layer (124) are mixed over a height that corresponds to ⅕

H to ¼

H, in particular 1/10 H to ⅕

H, where H is the total height H of the first and second layer.

26. The method of claim 1, wherein that the first layer (114) in its 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 (114, 124),

27. The method of claim 1, wherein the mixtures used for the first layer (114) and the second layer (124) are such that the quotient of the tetragonal crystal phase to the cubic crystal phase of the zirconium dioxide in both the first layer and the second layer will be a ≧

1 after pre-sintering.

28. A pre-sintered or fully sintered blank (28, 48, 133) that is manufactured in accordance with claim 1.

29. A pre-sintered or fully sintered blank (28, 48) to be used in the manufacture of a dental restoration (42), such as a dental framework, crown, partial crown, bridge, coping, veneer, abutment, post and core, in particular a crown or partial crown, comprising of a ceramic material that in particular contains zirconium dioxide, and possesses regions of different compositions, whereby a first region (28) includes of a first ceramic material (14) and at least a second region (34) includes of a second ceramic material (20) of a different composition, and the regions adjoin each other, whereby in particular the first ceramic material and/or the second ceramic material include of a mixture according to claim 1, wherein the second region (34, 52, 54, 56) extends within the first region (32) and possesses an outside geometry that narrows as the distance from a base region (35) or base surface increases.

30. The blank of claim 28, wherein the base region (35) or rather the base surface of the second region (34) extends in the area of an outer surface (33) of the first region (32), and preferably merges flushly with this surface.

31. The blank of claim 28, wherein that the second region (34) has a cavity (26) that originates from its base region (35), or rather base surface.

32. The blank of claim 28, wherein the second region (34) possesses a cone-like exterior geometry.

33. The blank of claim 28, wherein within the second region (34) extends a third region (38), which includes of a third ceramic material with a composition that is different from that of the first and/or second ceramic material (14, 20).

34. The blank of claim 28, wherein a first region (32, 50) encompasses several second regions (52, 54, 56).

35. The blank of claim 28, wherein at least a few of the several second regions (52, 54, 56) have differing exterior geometries.

36. The blank of claim 28, wherein the blank (28, 48) contains zirconium dioxide doped with yttrium oxide.

37. The blank of claim 28, wherein the yttrium oxide content in the second or third ceramic material (20) is between 4.5% by weight and 7.0% by weight, while it is between 7.0% by weight and 9.5% by weight in the first ceramic material (14), whereby the yttrium oxide content in the first ceramic material is greater than in the second ceramic material.

38. The blank of claim 28, wherein the second ceramic material (20) is colored differently from the first ceramic material (14).

39. The blank of claim 28, wherein the content of the element generating the;

fluorescent effect in the first ceramic material (14) is different from that in the second ceramic material (20).

40. The blank of claim 28, wherein after sintering to full density, the restoration (42) produced from the blank (28) possesses a higher strength on the dentine side than on the incisal side and/or a higher translucency on the incisal side than on the dentine side and/or in the dentine region a higher content of the element generating the fluorescence effect than in the incisal region.

41. The blank of claim 28, wherein the thermal expansion coefficient of the first region (32, 50) is 0.2 μ

m/m*K to 0.8 μ

m/m*K lower than the thermal expansion coefficient of the second and/or third region (34, 38).

42. The blank (133) of claim 28, wherein the blank (133) comprises at least three layers, one of which is a middle layer (128), which extends over at least 1/10 H to ⅕

H of the total height H of the blank, and which includes of a material of the first layer (114) and the second layer (124).

43. The blank of claim 42, wherein in the middle layer (128) the fraction of the material of the first layer (114) decreases along the direction from the first layer towards the_second layer (124) in a continuous or largely continuous manner.

44. The blank of claim 42, wherein the yttrium oxide content in the middle layer (128) increases from the first layer (114) towards the second layer (124) preferably in a continuous or largely continuous manner.

45. The blank of claim 42, wherein the first layer (114) is colored differently than the second layer (124) and/or contains different, amounts of the element generating the fluorescent effect.

46. The blank of claim 42, wherein after the sintering to completeness of the blank (133), the restoration (134) produced from the former exhibits, viewed along the tooth axis, a higher rigidity on the root side than on the incisal side and/or exhibits a higher translucency on the incisal side than on the root side.

47. A dental restoration (42), in particular a crown or partial crown, manufactured in accordance with claim 1, wherein the restoration (42) is embodied monolithically and includes at least of a first layer (32), which includes of a first ceramic material (14) and extends on the incisal side, and a second layer (34), which includes of a second ceramic material (20) and extends on the dentine side, whereby the first layer possesses a higher translucency and/or lower rigidity and/or a lower degree of fluorescence than the second layer.

48. The dental restoration of claim 47, wherein the thermal expansion coefficient of the first layer (32) is 0.2 μ

m/m*K to 0.8 μ

m/m*K lower than the thermal expansion coefficient of the second layer (34).

49. A dental restoration (134), in particular a crown, partial crown, or bridge, produced from a blank of claim 28, wherein the restoration (134), viewed along the axial direction of the tooth, includes of at least a first layer (140) extending on the root side, a second layer (124) extending on the incisal side, and, extending in between these, a middle layer (128) or intermediate layer (228), in which the strength decreases from the first layer towards the second layer in a continuous or largely continuous manner and/or in which the translucency increases continuously or largely continuously and/or in which the fluorescence characteristic decreases.