Lithium silicate glass ceramic for fabrication of dental appliances

• US 20120094822A1
• Filed: 12/08/2011
• Published: 04/19/2012
• Est. Priority Date: 04/11/2008
• Status: Active Grant

• Current Assignee: James R Glidewell Dental Ceramics Incorporated
• Original Assignee: James R Glidewell Dental Ceramics Incorporated
• Inventors: Castillo, Rodolfo
• Granted Patent: US 9,241,879 B2
• Time in Patent Office: Days
• US Class Current: 501/59
• CPC Class Codes: A61K 6/78 Pigments
• CPC Class Codes: A61K 6/804 comprising manganese oxide
• CPC Class Codes: A61K 6/807 comprising magnesium oxide
• CPC Class Codes: A61K 6/813 comprising iron oxide
• CPC Class Codes: A61K 6/818 comprising zirconium oxide
• CPC Class Codes: A61K 6/82 comprising hafnium oxide
• CPC Class Codes: A61K 6/833 Glass-ceramic composites
• CPC Class Codes: A61L 27/105 containing Al2O3
• CPC Class Codes: C03B 1/02 Compacting the glass batches, e.g. pelletising
• CPC Class Codes: C03B 19/02 by casting molten glass, e.g. injection moulding
• CPC Class Codes: C03B 32/02 Thermal crystallisation, e.g. for crystallising glass bodies into glass-ceramic articles C03B27/012 takes precedence
• CPC Class Codes: C03C 10/0027 containing SiO2, Al2O3, Li2O as main constituents
• CPC Class Codes: C03C 3/097 containing phosphorus, niobium or tantalum
• CPC Class Codes: C03C 3/118 containing aluminium
• CPC Class Codes: C03C 4/0021 for dental use

Abstract

The present invention relates to a method of fabricating an improved lithium silicate glass ceramic and to that material for the manufacture of blocks for dental appliances using a CAD/CAM process and hot pressing system. The lithium silicate material has a chemical composition that is different from those reported in the prior art with 1 to 10% of germanium dioxide in final composition. The softening points are close to the crystallization final temperature of 800° C. indicating that the samples will support the temperature process without shape deformation.

Claims

1. A lithium silicate ceramic glass made from a composition mixture comprising:

53% to 57% wt of SiO₂;

14 to 17% wt of Li₂O;

0.5 to 8% wt of GeO₂;

3.0 to 5.0% wt of Al₂O₃;

3.0 to 5.0% wt of K₂O;

0.0 to 2.0% wt of B₂O₃;

0.0 to 1.0% wt of CaO;

0.0 to 1.0% wt of Fluoride;

0.0 to 1.0% wt of MgO;

0 to 1.0% wt of CeO₂;

2.0 to 3.0% wt of P₂O₅; and

0 to 10% of coloring oxides.

2. The lithium silicate ceramic glass recited in claim 1 wherein said composition mixture also comprises at least one of the following components:

ZrO₂, TiO₂, Er₂O₃, V₂O₅, MnO₂, Tb₄O₇, Ta₂O₅, Sm₂O₃, Pr₂O₃, Y₂O₃, Nb₂O₅, SnO, and Eu₂O₃.

6. The lithium silicate glass ceramic recited in claim 1 comprising a molar ratio of SiO₂/Li₂O between 1.7 and 1.9

3. A lithium silicate ceramic glass made from a composition mixture comprising:

about 56.0% wt SiO₂;

about 16.0% wt Li₂O;

about 4.5% wt K₂O; and

about 4.2% wt of Al₂O₃;

about 5.0% wt of ZrO₂,

about 5.0% wt of Sm₂O₃

and about % 2.0 wt of GeO₂.

4. The lithium silicate ceramic glass recited in claim 3 wherein said composition mixture also comprises at least 3.0% wt of each of the following components:

P₂O₅, Pr₂O₃ and Y₂O₃.

5. The lithium silicate ceramic glass recited in claim 4 further comprising at least one of the following additional components:

TiO₂, SnO, Eu₂O₃, Er₂O₃, Nb₂O₃ and V₂O₅.

7. A method of fabricating lithium silicate glass;

the method comprising the steps of;

(a) blending a mix of precursors;

(b) ball milling the mix to homogenize the components of the mix for 2 to 4 hours;

(c) calcining the resulting mix of step (b) for about 4 to 5 hours at a temperature of 700 to 800°

C.;

(d) ball-milling the calcined mix of step (c) to homogenize the components of the mix for 2 to 4 hours;

(e) melting the resulting mix of step (d) at a temperature of 1100 to 1200°

C. for 3 to 6 hours; and

(f) pouring the melt of step (e) into graphite molds to form shaped blanks and cooling such blanks to room temperature.

8. The method of fabricating dental restorations of lithium silicate glass ceramic as recited in claim 7;

the method comprising the additional steps of;

(g) heating the blanks from room temperature to 600°

C. at 1°

C./min, and holding the blanks for 40 to 50 min at 600°

C.;

(h) milling the blanks of step (g) into dental restorations; and

(i) heating the restoration of step (h) at temperature of 350°

to 800°

C. for 10 to 15 minutes.

9. The method of fabricating dental restorations of lithium silicate glass ceramic as recited in claim 7;

the method comprising the additional steps of;

(g) heating the blanks from room temperature to 800°

C. at 15°

C./min for 10 to 40 minutes; and

(h) hot pressing the blanks of step (g) into dental restorations at a temperature of 800°

to 840°

C.

10. The method of claim 8 wherein the final crystalline product is lithium silicate.

11. The method of claim 9 wherein the final crystalline product is lithium silicate.

12. The method of claim 7 wherein one of said precursors in step (a) is germanium oxide

13. The method of fabricating lithium silicate glass recited in claim 7 wherein said mix of precursors of step (a) employs a molar ratio of SiO₂/Li₂O which is between 1.7 and 1.9.