LITHIUM SILICATE GLASS CERAMIC AND LITHIUM SILICATE GLASS COMPRISING A DIVALENT METAL OXIDE

• US 20140228196A1
• Filed: 10/11/2012
• Published: 08/14/2014
• Est. Priority Date: 10/14/2011
• Status: Active Grant

• Current Assignee: Ivoclar Vivadent AG
• Original Assignee: Ivoclar Vivadent AG
• Inventors: Ritzberger, Christian, Apel, Elke, Hland, Wolfram, Rheinberger, Volker
• Granted Patent: US 9,232,989 B2
• Time in Patent Office: Days
• US Class Current: 501/32
• CPC Class Codes: A61C 13/00 Dental prostheses; Making same tooth crowns for capping teeth A61C5/70; dental implants A61C8/00
• CPC Class Codes: A61C 13/0022 Blanks or green, unfinished dental restoration parts
• CPC Class Codes: A61C 13/082 Cosmetic aspects, e.g. inlays; Determination of the colour A61C19/10 takes precedence
• CPC Class Codes: A61C 13/083 Porcelain or ceramic teeth A61C13/081 takes precedence; preparations A61K6/80
• CPC Class Codes: A61K 6/80 Preparations for artificial teeth, for filling teeth or for capping teeth
• CPC Class Codes: A61K 6/802 comprising ceramics
• 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 10/00 Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition
• CPC Class Codes: C03C 10/0009 containing silica as main constituent
• CPC Class Codes: C03C 10/0027 containing SiO2, Al2O3, Li2O as main constituents
• CPC Class Codes: C03C 3/076 with 40% to 90% silica, by weight C03C3/045 takes precedence
• CPC Class Codes: C03C 3/095 containing rare earths
• CPC Class Codes: C03C 3/097 containing phosphorus, niobium or tantalum
• CPC Class Codes: C03C 4/0021 for dental use
• CPC Class Codes: Y10T 29/49567 Dental appliance making

Abstract

Lithium silicate glass ceramics and glasses containing specific oxides of divalent elements are described which crystallize at low temperatures and are suitable in particular as dental materials.

Claims

1. Lithium silicate glass ceramic which comprises a divalent metal oxide selected from MgO, CaO, SrO, BaO, ZnO and mixtures thereof and comprises at least 12.1 wt.-% Li₂O.

2. Glass ceramic according to claim 1, wherein lithium silicate glass ceramic is excluded which comprises at least 6.1 wt.-% ZrO₂.

3. Glass ceramic according to claim 1, wherein lithium silicate glass ceramic is excluded which comprises at least 8.5 wt.-% transition metal oxide selected from the group consisting of oxides of yttrium, oxides of transition metals with an atomic number from 41 to 79 and mixtures of these oxides.

4. Glass ceramic according to claim 1, which comprises less than 1.0.

5. Glass ceramic according to claim 1, which comprises less than 1.0 wt.-% K₂O, Na₂O and mixtures thereof.

6. Glass ceramic according to claim 1, which comprises less than 1.0 wt.-% further alkali metal oxide.

7. Glass ceramic according to claim 1, which comprises less than 0.1 wt.-% La₂O₃.

8. Glass ceramic according to claim 1, which comprises the divalent metal oxide or mixtures thereof in an amount of from 0.1 to 15 wt.-%.

9. Glass ceramic according to claim 1, wherein the divalent metal oxide is SrO.

10. Glass ceramic according to claim 1, which has lithium metasilicate as a main crystal phase and.

11. Glass ceramic according to claim 1, which has lithium disilicate as a main crystal phase and.

12. Glass ceramic according to claim 1, which comprises 55.0 to 85.0 wt.-% SiO₂.

13. Glass ceramic according to claim 1, which comprises 12.5 to 20.0 wt.-% Li₂O.

14. Glass ceramic according to claim 1, which comprises 0 to 10.0 wt.-% P₂O₅.

15. Glass ceramic according to claim 1, which comprises at least one of the following components:

16. Lithium silicate glass ceramic according claim 1, which has lithium disilicate as a main crystal phase and a fracture toughness, measured as K_IC value, of at least 1.9 MPa·

m^0.5.

17. Lithium silicate glass ceramic according to claim 1, which comprises SiO₂ and Li₂O in a molar ratio of from 1.7 to 3.1.

18. Lithium silicate glass ceramic according to claim 1, which comprises less than 5.0 wt.-% BaO.

19. Starting glass, which comprises the components of the glass ceramic according to claim 1.

20. Lithium silicate glass with nuclei which are suitable for forming lithium metasilicate and/or lithium disilicate crystals, wherein the glass comprises the components of the glass ceramic according to claim 1.

21. Glass ceramic according to claim 1, wherein the glass ceramic is present in the form of a powder, a granular material, a blank or a dental restoration.

22. Process for the preparation of the glass ceramic according to claim 1, wherein a glass ceramic with lithium metasilicate as main crystal phase is subjected to at least one heat treatment in the range of from 450 to 950°

C.

23. Process according to claim 22, wherein

(a) a starting glass is subjected to a heat treatment at a temperature of from 470 to 560°

C. in order to form the glass with nuclei, and

(b) the glass with nuclei is subjected to a heat treatment at a temperature of from 600 to 750°

C. in order to form the glass ceramic with lithium disilicate as main crystal phase.

24. A method of using the glass ceramic according to claim 1 as dental material.

25. The method according to claim 24, wherein the glass ceramic is shaped by pressing or machining to a desired dental restoration.

26. Glass ceramic according to claim 1, which has lithium metasilicate as a main crystal phase and has more than 5 vol. % lithium metasilicate crystals.

27. Glass ceramic according to claim 1, which has lithium disilicate as a main crystal phase and has more than 10 vol. % lithium disilicate crystals.