Process for Producing a Colored Dental Zirconia Article

Patent metadata

Field	Value
Publication number	US-2022133601-A1
Application number	US-202017310668-A
Country	US
Kind code	A1
Filing date	Mar 2, 2020
Priority date	Mar 4, 2019
Publication date	May 5, 2022
Grant date	—

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

1 . A process of producing a colored dental zirconia article,
the process comprising the sintering of 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, preferably in an amount in the range of 0.005 to 0.70 wt. % with respect to the porous dental zirconia article, calculated on the amount of Tb 4 O 7 ,
the porous dental zirconia article being essentially free of Fe components.

2 . The process according to claim 1 , the porous dental zirconia article being characterized by the following features alone or in combination:
average connected pore diameter of 40 to 150 nm; BET surface: 5 to 15 m 2 /g; density: 2.5 to 4 g/cm 3 ; average grain size: 50 to 200 nm; coefficient of thermal expansion: 8.5*10 −6 K −1 to 11.5*10 −6 K −1 .

3 . The process according to claim 1 , the porous dental zirconia article comprising:
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. %, Al 2 O 3 in an amount of 0.05 to 0.12 wt. %, wt. % with respect to the weight of the porous dental zirconia article.

4 . The process according to claim 1 , the porous dental zirconia article comprising in addition coloring components comprising Mn, Er, Co, Cr, Ni, V, Nd or combinations thereof.

5 . The process according to claim 1 , the porous dental zirconia article comprising in addition a fluorescing component.

6 . The process of producing a dental zirconia article in particular according to claim 1 , the process comprising the following steps:
providing a porous dental zirconia mill blank, machining a porous dental zirconia article from the porous zirconia dental mill blank, the porous zirconia article having an outer and an inner surface, sintering the porous dental 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 at least 1 min,
optionally a heat-treatment segment C with a heating rate of 0 K/sec for at least 1 min,
wherein the heat-treatment segment B is conducted after the heat-treatment segment A and the optional heat-treatment segment C is conducted after the heat-treatment segment B,
cooling down the heat-treated zirconia article to room temperature, the 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, preferably 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 ,
the porous dental zirconia article being essentially free of Fe components.

7 . The process according to claim 1 , the coloring component containing Tb having a particle size below 100 nm.

8 . The process according to claim 1 comprising the additional step of applying a glazing composition to the outer surface of the porous zirconia article before the heat-treatment is conducted.

9 . The process according to claim 8 , the glazing composition comprising a glass being characterized by comprising either of the following compositions:

SiO 2
80 to 98
80 to 98
80 to 98
80 to 98
80 to 98
85 to 98
80 to 98

B 2 O 3
0 to 15
0 to 15
2 to 15

2 to 15

Na 2 O
0 to 5
0 to 5

K 2 O
0 to 5
0 to 5

0.1 to 5
0.1 to 5

5 to 10

Al 2 O 3
0 to 5
0 to 5
0.1 to 5
0.1 to 5
0.1 to 5

8 to 12

La 2 O 3
0 to 1
0 to 1

MgO
0 to 5
0 to 5

0.1 to 5
0.1 to 5

CaO
0 to 2
0 to 2

SrO
0 to 2
0 to 2

BaO
0 to 2
0 to 2

Bi 2 O 3
0 to 0.5
0 to 0.5

Eu 2 O 3
0 to 1
0.05 to 1

0 to 1

wherein the amounts are given in mol % with respect to the glass composition.

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

11 . The process according to claim 1 , the porous dental zirconia article not comprising the following components alone or in combination:
glass; glass ceramic; oxides of Si, Fe, K, Na; in an amount above 1 wt. % with respect to the weight of the material of the porous zirconia dental article.

12 . The process according to claim 1 , the dental zirconia article after sintering being characterized by the following features alone or in combination:
density: at least 98.5% of theoretical density; biaxial flexural strength: 500 to 1,500 MPa determined according to ISO 6872:2015; phase content tetragonal phase: 20 to 80 wt. %; phase content cubic phase: 20 to 80 wt. %; translucency: 25% or more determined on a sample having a thickness of 1 mm in reflection mode at a wave length of 400 to 700 nm.

13 . The process according to claim 1 , the dental zirconia article having the shape a dental bridge, crown, veneer, facing, abutment, inlay, onlay and parts thereof.

14 . Use of the porous dental zirconia article as described in claim 1 for producing a sintered dental zirconia rest

Assignees

• 3M Innovative Properties Co

Inventors

• Jahns Michael
• Goetzinger Martin
• Schmittner Sybille A

Classifications

• C04B2235/762

  Cubic symmetry, e.g. beta-SiC · CPC title

• C04B2235/9607

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

• A61K6/833

  Glass-ceramic composites · CPC title

• C04B2235/612

  Machining · CPC title

• C04B2111/00836

  for medical or dental applications · CPC title