Process for producing a blank, and a blank

Patent metadata

Field	Value
Publication number	US-9737465-B2
Application number	US-201414892369-A
Country	US
Kind code	B2
Filing date	Apr 30, 2014
Priority date	May 3, 2013
Publication date	Aug 22, 2017
Grant date	Aug 22, 2017

Abstract

The invention relates to a blank for producing a dental molded part such as an inlay, onlay, crown or bridge, and to a method for producing the blank. To be able to machine a dental molded part, in particular one having thin wall thicknesses, from the blank without difficulty, the blank is designed to consist of a glass ceramic having a density of between 30 and 60% of theoretical density, and of glass-ceramic powder particles with a particle size distribution d 90 ≦80 μm, lithium silicate crystals being present in an amount of 10 to 90% by volume.

First claim

The invention claimed is:

1. A blank for producing a dental molded part, the blank comprising:
pre-crystalized glass-ceramic powder particles having lithium silicate crystals; and
wherein the blank has a density between 30% and 60% of a theoretical density of a fully-sintered blank; and
wherein the blank is formed from the pre-crystalized glass-ceramic powder particles having a grain size distribution d 50 ≦25 μm; and
wherein a fraction of lithium silicate crystals is between 10% by volume and 90% by volume and wherein: the blank possesses a disk-, cube-, or rod-shaped geometry, and means for arrangement in a milling machine originating from the circumferential surface of the blank and extending diametrically relative to the center of gravity.

2. The blank of claim 1 , wherein: the blank possesses an open porosity between 5% by volume and 60% by volume.

3. A blank for producing a dental molded part, the blank comprising:
pre-crystalized glass-ceramic powder particles having lithium silicate crystals;
wherein the blank has a density between 30% and 60% of a theoretical density of a fully-sintered blank; and
the pre-crystalized glass-ceramic powder particles having a grain size distribution d 90 ≦80 μm;
wherein a fraction of lithium silicate crystals is between 10% by volume and 90% by volume and wherein the pre-crystalized glass-ceramic powder particles possess a composition in % by weight:

SiO 2 46.0-72.0;
Li 2 O 10.0-25.0;
ZrO 2 6.5-14.0;
P 2 O 5 1.0-10.0;
Al 2 O 3 0.1-8.0;
K 2 O 0.1-5.0;
CeO 2 0.1-4.0;
B 2 O 3 0.0-4.0;
Na 2 O 0.0-4.0;
Tb 4 O 7 0.0-2.5; and
0.0 to 4.0 of at least one additive.

4. The blank of claim 1 , wherein the pre-crystalized glass-ceramic powder particles possess a composition in % by weight:
SiO 2 49.0-69.0;
Li 2 O 11.5-24.0;
ZrO 2 7.0-13.5;
P 2 O 5 1.5-9.0;
Al 2 O 3 0.2-7.5;
K 2 O 0.2-4.5;
CeO 2 0.2-3.5;
B 2 O 3 0.0-3.5;
Na 2 O 0.0-3.5;
Tb 4 O 7 0.0-2.0; and
0.0 to 4.0 of at least one additive.

5. The blank of claim 4 , wherein the pre-crystalized glass-ceramic powder particles possess a composition in % by weight:
SiO 2 52.0-66.0;
Li 2 O 12.0-22.5;
ZrO 2 7.5-13.0;
P 2 O 5 2.0-8.5;
Al 2 O 3 0.3-7.0;
K 2 O 0.3-4.0;
CeO 2 0.3-3.5;
B 2 O 3 0.0-3.0;
Na 2 O 0.0-3.0;
Tb 4 O 7 0.0-2.0; and
0.0 to 4.0 of at least one additive.

6. The blank of claim 3 , wherein the pre-crystalized glass-ceramic powder particles possess a composition in % by weight of:
SiO 2 55.0-63.0;
Li 2 O 12.5-21.5;
ZrO 2 8.0-12.0;
P 2 O 5 2.5-8.0;
Al 2 O 3 0.4-6.5;
K 2 O 0.4-4.0;
CeO 2 0.5-3.0;
B 2 O 3 0.0-3.0;
Na 2 O 0.0-3.0;
Tb 4 O 7 0.0-2.0; and
0.0 to 4.0 of at least one additive.

7. The blank of claim 1 , wherein the pre-crystalized glass-ceramic powder particles possess a composition in % by weight:
SiO 2 58-60;
Li 2 O 13.5-20.5;
ZrO 2 8.5-11.5;
P 2 O 5 3.0-7.5;
Al 2 O 3 0.5-6.0;
K 2 O 0.5-3.5;
CeO 2 0.5-2.5;
B 2 O 3 0-3;
Na 2 O 0-3;
Tb 4 O 7 0-1.5; and
0.0 to 4.0 of at least one additive.

8. The blank of claim 3 , wherein: the additive is selected from the group consisting of: color pigment, and fluorescent agent.

9. The blank of claim 3 , wherein: the additive comprises at least one oxide selected from the group consisting of BaO, CaO, MgO, MnO, Er 2 O 3 , Gd 2 O 3 , Pr 6 O 11 , Sm 2 O 3 , TiO 2 , V 2 O 5 , and Y 2 O 3 .

10. The blank of claim 1 , wherein: the fraction of lithium silicate crystals is between 40% by volume and 60% by volume.

11. A method for producing a dental molded part, the method comprising the steps of:
producing a molten mass with a composition (in % by weight):
SiO 2 46.0-72.0;

Li 2 O 10.0-25.0;
ZrO 2 6.5-14.0;
P 2 O 5 1.0-10.0;
Al 2 O 3 0.1-8.0;
K 2 O 0.1-5.0;
CeO 2 0.1-4.0;
B 2 O 3 0.0-4.0;
Na 2 O 0.0-4.0;
Tb 4 O 7 0.0-2.5; and
0.0 to 4.0 of at least one additive,
producing a glass frit by atomizing the molten mass and quenching the molten mass in a medium,
generating glass powder particles from the glass frit with a grain size distribution d 90 <80 μm,
crystallizing lithium silicate crystals with a volume fraction between 10% and 90% by a first thermal treatment of either the glass frit or the glass powder particles in a first temperature range at a temperature T 1 with 500° C.≦T 1 ≦750° C. for a duration t 1 with 5 min≦t 1 ≦120 min, whereby, glass-ceramic powder particles with a grain size distribution d 90 ≦80 μm are produced from a heat-treated glass frit,
pressing the glass-ceramic powder particles to form a blank,
machining the blank by milling to produce a pre-form part corresponding to the dental molded part, taking into consideration the shrinkage characteristics of the blank, and
sintering the pre-form part at a temperature T 2 with 800° C.≦T 2 ≦1050° C. for a duration t 2 with 5 min≦t 2 ≦60 min.

12. The method of claim 11 , wherein the molten mass comprises (in % by weight):
SiO 2 49.0-69.0;
Li 2 O 11.5-24.0;
ZrO 2 7.0-13.5;
P 2 O 5 1.5-9.0;
Al 2 O 3 0.2-7.5;
K 2 O 0.2-4.5;
CeO 2 0.2-3.5;
B 2 O 3 0.0-3.5;
Na 2 O 0.0-3.5;
Tb 4 O 7 0.0-2.0; and
0.0 to 4.0 of at least one additive.

13. The method of claim 11 , wherein the molten mass comprises (in % by weight):
SiO 2 52.0-66.0;
Li 2 O 12.0-22.5;
ZrO 2 7.5-13.0;
P 2 O 5 2.0-8.5;
Al 2 O 3 0.3-7.0;
K 2 O 0.3-4.0;
CeO 2 0.3-3.5;
B 2 O 3 0.0-3.0;
Na 2 O 0.0-3.0;
Tb 4 O 7 0.0-2.0; and
0.0 to 4.0 of at least one additive.

14. The method of claim 11 , wherein the molten mass comprises (in % by weight):
SiO 2 55.0-63.0;
Li 2 O 12.5-21.5;
ZrO 2 8.0-12.0;
P 2 O 5 2.5-8.0;
Al 2 O 3 0.4-6.5;
K 2 O 0.4-4.0;
CeO 2 0.5-3.0;
B 2 O 3 0.0-3.0;
Na 2 O 0.0-3.0;
Tb 4 O 7 0.0-2.0; and
0.0 to 4.0 of at least one additive.

15. The method of claim 11 , wherein the molten mass comprises (in % by weight):
SiO 2 58-60;
Li 2 O 13.5-20.5;
ZrO 2 8.5-11.5;
P 2 O 5 3.0-7.5;
Al 2 O 3 0.5-6.0;
K 2 O 0.5-3.5;
CeO 2 0.5-2.5;
B 2 O 3 0-3;
Na 2 O 0-3;
Tb 4 O 7 0-1.5; and
0.0 to 4.0 of at least one additive.

16. The method of claim 11 , wherein: prior to machining and after the first thermal treatment, the blank is tempered at a temperature T 3 with 750° C.≦T 3 ≦900° C. for a duration t 3 with 5 min≦t 3 ≦30 min.

17. The method of claim 11 , wherein: to produce a blank with a disk geometry, the glass-ceramic powder particles are first axial pressed and subsequently, upon insertion into an encasing element such as a pouch coated with polyethylene on its inside, are subjected to isostatic re-compression, whereby the re-compression in particular is performed at a pressure p n with 250 MPa≦p n ≦350 MPa for a time t 4 with 5 sec≦t 4 ≦30 sec.

18. The method of claim 11 , wherein: for the production of a blank with a cube geometry, the glass-ceramic powder particles are axially pressed successively and in particular continuously with increasing pressure for a duration t 5 with 10 sec≦t 5 ≦20 sec, whereby the maximum pressure is p 5 , with 50 MPa≦p 5 ≦400 MPa.

19. The method of claim 11 , wherein: for the production of a rod-shaped blank, the glass-ceramic powder is introduced into a tubular press mould and subsequently is subjected to quasi-isostatic pressing.

20. The method of claim 11 , wherein:
the blank is subjected to at least a coarse machining by mill

Assignees

• Dentsply Int Inc

Inventors

• Fecher Stefan
• Hörhold Heiner
• Schusser Udo
• Vollmann Markus
• Kutzner Martin

Classifications

• A61K6/833 Primary

  Glass-ceramic composites · CPC title

• A61C13/0022 Primary

  Blanks or green, unfinished dental restoration parts · CPC title

• A61K6/818

  comprising zirconium oxide · CPC title

• C03C4/0021

  for dental use · CPC title

• C03C3/097

  containing phosphorus, niobium or tantalum · CPC title