Process for producing a blank, and a blank

Patent metadata

Field	Value
Publication number	US-2016113845-A1
Application number	US-201414892369-A
Country	US
Kind code	A1
Filing date	Apr 30, 2014
Priority date	May 3, 2013
Publication date	Apr 28, 2016
Grant date	—

Abstract

The invention relates to a blank for producing a dental moulded part such as an inlay, onlay, crown or bridge, and to a method for producing the blank. To be able to machine a dental moulded 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

1 . A blank for producing a dental molded part, the blank comprising:
lithium silicate crystals; glass ceramics with a density between 30% and 60% of a theoretical density of a fully-sintered blank; and glass-ceramic powder particles with a grain size distribution d 90 ≦80 μm; wherein a fraction of lithium silicate crystals is between 10% by volume and 90% by volume.

2 . The blank of claim 1 , wherein:
the glass-ceramic powder particles exhibit a grain size distribution d 50 ≦25 μm.

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

4 . The blank of claim 1 , wherein:
the blank possesses a disk-, cube-, or rod-shaped geometry, for arrangement in a milling machine originating from the circumferential surface of the blank and extending diametrically relative to the center of gravity.

5 . The blank of claim 1 , wherein the 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.

6 . The blank of claim 1 , wherein the 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.

7 . The blank of claim 1 , wherein the 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.

8 . The blank of claim 1 , wherein the 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.

9 . The blank of claim 1 , wherein the 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.

10 . The blank of claim 5 , wherein:
the additive is selected from the group consisting of: color pigment and fluorescent agent.

11 . The blank of claim 5 , 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 .

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

13 . 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.

14 . The method of claim 13 , 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.

15 . The method of claim 13 , 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.

16 . The method of claim 13 , 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.

17 . The method of claim 13 , 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.

18 . The method of claim 13 , 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.

19 . The method of claim 13 , 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.

20 . The method of claim 13 , 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.

21 . The method of claim 13 , 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.

22 . The method of claim 13 , wherein:
the blank is subjected to at least a coarse machining by milling and subsequent precision machining, whereby milling parameters for the coarse machining comprise: Cutter diameter: 2 to 5 mm, Feed: 500 to 4000 mm/min, Lateral feed ae: 0.2 to 3 mm, Depth feed ap: 0.1 to 2 mm, Cutter speed: 10.000 to 50.000 l/min, and the milling parameters for the precision machining comprise: Cutter diameter: 0.3 to 1.5 mm, Feed: 300 to 2000 mm/min, Lateral feed ae: 0.2 to 0.6 mm, Depth feed ap: 0.05 to 0.3 mm, Cutter speed: 20,000 to 60,000 l/min.

23 . Th

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

• C03C3/097

  containing phosphorus, niobium or tantalum · CPC title

• C03B19/06

  by sintering, {e.g. by cold isostatic pressing of powders and subsequent sintering, by hot pressing of powders, by sintering slurries or dispersions not undergoing a liquid phase reaction} · CPC title