Process for producing a colored dental zirconia article

Patent metadata

Field	Value
Publication number	US-12502337-B2
Application number	US-202017310668-A
Country	US
Kind code	B2
Filing date	Mar 2, 2020
Priority date	Mar 4, 2019
Publication date	Dec 23, 2025
Grant date	Dec 23, 2025

Abstract

The invention relates to a process of producing a dental zirconia article, the process comprising the step of sintering a porous dental zirconia article, the sintering comprising a heat-treatment segment A characterized by a heating rate of at least 3 K/sec up to a temperature of at least 1,200° C., the porous dental zirconia article being composed of a zirconia material containing 6.0 to 8.0 wt. % yttria, 0.05 to 0.12 wt. % alumina and comprising a coloring component containing Tb, the porous dental zirconia article being essentially free of Fe components. The invention also relates to a process comprising the additional step of applying a glazing composition to the outer surface of the porous zirconia article before the heat-treatment or sintering is conducted.

First claim

The invention claimed is:

1 . A process of producing a colored dental zirconia article, the process comprising:
applying a glazing composition to an outer surface of a porous dental zirconia article before conducting a heat-treatment segment A, the glazing composition comprising a glass comprising at least 80 mol % SiO 2 , wherein the amount is given in mol % with respect to the glass; and sintering the porous dental zirconia article, the sintering comprising:
the heat-treatment segment A with a heating rate of at least 3 K/sec up to a temperature of at least 1,200° C., and
a heat-treatment segment B with a heating rate that is lower than the heating rate of heat-treatment segment A and is conducted after the heat-treatment segment A for at least 1 minute,
wherein the porous dental zirconia article comprises a zirconia material containing 6.0 to 8.0 wt. % yttria, 0.05 to 0.12 wt. % alumina, and a coloring component containing Tb in an amount of 0.005 to 0.70 wt. % with respect to the porous dental zirconia article calculated on the amount of Tb 4 O 7 , and
wherein the porous dental zirconia article is essentially free of Fe components.

2 . The process according to claim 1 , wherein the porous dental zirconia article comprises at least one of:
an average connected pore diameter of 40 to 150 nm; a surface area of 5 to 15 m 2 /g, determined by nitrogen adsorption analysis; a density of 2.5 to 4 g/cm 3 ; an average grain size of 50 to 200 nm; or a coefficient of thermal expansion of 8.5*10 −6 K −1 to 11.5*10 −6 K −1 .

3 . The process according to claim 1 , wherein the porous dental zirconia article comprises at least one of:
ZrO 2 in an amount of 88.8 to 93.9 wt. %, HfO 2 in an amount of 0 to 3 wt. %, Y 2 O 3 in an amount of 6.0 to 8.0 wt. %, or Al 2 O 3 in an amount of 0.05 to 0.12 wt. %, each wt. % with respect to a total weight of the porous dental zirconia article.

4 . The process according to claim 1 , wherein the porous dental zirconia article includes at least one additional coloring component comprising one or more of: Mn, Er, Co, Cr, Ni, V, or Nd.

5 . The process according to claim 1 , wherein the porous dental zirconia article comprises a fluorescing component.

6 . The process according to claim 1 , further comprising:
providing a porous dental zirconia mill blank, machining a porous dental zirconia article from the porous zirconia dental mill blank, the porous dental zirconia article having an outer surface and an inner surface, sintering the porous dental zirconia article to provide a heat-treated zirconia article, the sintering comprising:
a heat-treatment segment A with a heating rate of at least 3 K/sec to a temperature of at least 1,200° C.,
a heat-treatment segment B with a heating rate of 0 to 1 K/sec for a duration of no more than 10 minutes up to a temperature of at least 1,300° C., and
optionally, a heat-treatment segment C with a heating rate of 0 K/sec for at least 1 min, wherein the optional heat-treatment segment C is conducted after the heat-treatment segment B; and
cooling down the heat-treated zirconia article to room temperature,
wherein the porous dental zirconia article comprises the coloring component in an amount of 0.005 to 0.50 wt. % with respect to the porous dental zirconia article calculated on the amount of Tb 4 O 7 .

7 . The process according to claim 1 , wherein the glazing composition comprises a glass comprising at least one of the following compositions:
i) Composition 1: SiO 2 : 80 to 98 mol % B 2 O 3 : 0 to 15 mol % Na 2 O: 0 to 5 mol % K 2 O: 0 to 5 mol % Al 2 O 3 : 0 to 5 mol % La 2 O 3 : 0 to 1 mol % MgO: 0 to 5 mol % CaO: 0 to 2 mol % SrO: 0 to 2 mol % BaO: 0 to 2 mol % Bi 2 O 3 : 0 to 0.5 mol % Eu 2 O 3 : 0 to 1 mol % ii) Composition 2: SiO 2 : 80 to 98 mol % B 2 O 3 : 0 to 15 mol % Na 2 O: 0 to 5 mol % K 2 O: 0 to 5 mol % Al 2 O 3 : 0 to 5 mol % La 2 O 3 : 0 to 1 mol % MgO: 0 to 5 mol % CaO: 0 to 2 mol % SrO: 0 to 2 mol % BaO: 0 to 2 mol % Bi 2 O 3 : 0 to 0.5 mol % Eu 2 O 3 : 0.05 to 1 mol % iii) Composition 3: SiO 2 : 80 to 98 mol % B 2 O 3 : 2 to 15 mol % Al 2 O 3 : 0.1 to 5 mol % iv) Composition 4: SiO 2 : 80 to 98 mol % K 2 O: 0.1 to 5 mol % Al 2 O 3 : 0.1 to 5 mol % MgO: 0.1 to 5 mol % v) Composition 5: SiO 2 : 80 to 98 mol % K 2 O: 0.1 to 5 mol % Al 2 O 3 : 0.1 to 5 mol % MgO: 0.1 to 5 mol % Eu 2 O 3 : 0 to 1 mol % vi) Composition 6: SiO 2 : 85 to 98 mol % B 2 O 3 : 2 to 15 mol % vii) Composition 7: SiO 2 : 80 to 98 mol % K 2 O: 5 to 10 mol % Al 2 O 3 : 8 to 12 mol % wherein the amounts are given in mol % with respect to the glass.

8 . The process according to claim 1 , wherein the glazing composition comprises a glass comprising at least one of:
a viscosity of at least 10 4 Pa*s at a temperature range of 1,300° C.; a coefficient of thermal expansion of 1*10 −6 K −1 to 10*10 −6 K −1 ; a surface tension of 210 to 300 mN/m at 1,300° C.; a Littleton softening point viscosity at a temperature of 1,100° C. to 1,350° C.; or a flow point viscosity at a temperature of 1,300° C. to 1,650° C.

9 . The process according to claim 1 , wherein the porous dental zirconia article, after sintering, comprises at least one of:
a density of at least 98.5% of the corresponding theoretical density; a biaxial flexural strength of 500 to 1,500 MPa, determined according to ISO 6872:2015; a phase content of tetragonal phase of 20 to 80 wt. %; a phase content of cubic phase of 20 to 80 wt. %; or a translucency of 25% or more, determined on a sample having a thickness of 1 mm in reflection mode at a wavelength of 400 to 700 nm.

10 . The process according to claim 1 , wherein the porous dental zirconia article comprises a shape of at least one of: a dental bridge, crown, veneer, facing, abutment, inlay, onlay, or parts thereof.

11 . The process according to claim 1 , further comprising:
utilizing the porous dental zirconia article to produce a sintered dental zirconia restoration, the process of producing the sintered dental zirconia restoration comprising heat-treating the porous dental zirconia article with the glazing composition located on the outer surface of the porous dental zirconia article, wherein the glazing composition comprises the glass in combination with a liquid.

12 . The process according to claim 1 , wherein the porous dental zirconia article comprises:
Zr oxide calculated as ZrO 2 : from about 88.8 to about 93.9 wt. %, Y oxide calculated as Y 2 O 3 : from about 6.0 to about 8.0 wt. %, Al oxide calculated as Al 2 O 3 : from about 0.05 to about 0.12 wt. %, or Tb oxide calculated as Tb 2 O 3 : from about 0.01 to about 0.50 wt. %, wt. % with respect to a weight of the porous dental zirconia article.

13 . The process according to claim 1 , wherein the coloring component containing Tb is incorporated into the zirconia material by co-precipitation of zirconia and the coloring component from a solution.

14 . The process according to claim 1 , wherein the porous dental zirconia article further comprises
a fluorescing component selected from oxides of Bi, present in an amount of 0.005 to 0.50 wt. % with respect to the weight of the porous dental zirconia article calculated on the amount of Bi 2 O 3 .

15 . The process according to claim 1 , wherein the coloring component is uniformly distributed within the zirconia material using a fluidized-bed reactor.

16 . A process of producing a colored dental zirconia article, the process comprising:
providing a porous dental

Assignees

• Solventum Intellectual Properties Company

Inventors

• Jahns Michael
• Goetzinger Martin
• Schmittner Sybille A

Classifications

• C04B2235/9661

  Colour · CPC title

• C04B2235/9653

  Translucent or transparent ceramics other than alumina · CPC title

• C04B2235/9607

  Thermal properties, e.g. thermal expansion coefficient · CPC title

• C04B2235/785

  Submicron sized grains, i.e. from 0,1 to 1 micron · CPC title

• C04B2235/765

  Tetragonal symmetry · CPC title