Lithium silicate glass ceramic and lithium silicate glass comprising a trivalent metal oxide

Patent metadata

Field	Value
Publication number	US-9402699-B2
Application number	US-201214001184-A
Country	US
Kind code	B2
Filing date	Oct 11, 2012
Priority date	Oct 14, 2011
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

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

First claim

The invention claimed is:

1. Lithium silicate glass ceramic which comprises a trivalent metal oxide selected from Y 2 O 3 , La 2 O 3 , Yb 2 O 3 , Bi 2 O 3 and mixtures thereof, wherein the glass ceramic is substantially free from K 2 O and Na 2 O and has lithium metasilicate as a main crystal phase.

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

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 0.1 wt.-% MgO and ZnO.

5. Glass ceramic according to claim 1 , wherein the trivalent metal oxide is selected from Y 2 O 3 , Yb 2 O 3 , Bi 2 O 3 and mixtures thereof.

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

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

8. Glass ceramic according to claim 1 , which comprises 55.0 to 85.0 wt.-% SiO 2 .

9. Glass ceramic according to claim 1 , which comprises 13.0 to 21.0 wt.-% Li 2 O.

10. Glass ceramic according to claim 1 , which comprises 0 to 8.0 wt.-% P 2 O 5 .

11. Glass ceramic according to claim 1 , which comprises SiO 2 and Li 2 O in a molar ratio of from 1.7 to 3.1.

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

Component
wt.-%

SiO 2
68.0 to 78.0

Li 2 O
13.0 to 20.0

trivalent metal oxide
2.0 to 6.0

and mixtures thereof

Al 2 O 3
  0 to 6.0

Rb 2 O and/or Cs 2 O
  0 to 5.0

P 2 O 5
   0 to 4.5.

13. Lithium silicate glass ceramic according to claim 1 , which has lithium disilicate as main crystal phase and a fracture toughness, measured as K IC value, of at least 1.8 MPa·m 0.5 .

14. 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.

15. Process for the preparation of the glass ceramic according to claim 1 , wherein a starting glass, a glass with nuclei or a glass ceramic with lithium metasilicate as a main crystal phase is subjected to at least one heat treatment in the range of from 450 to 950° C., in particular 450 to 750 and preferably 480 to 720° C.

16. Process according to claim 15 , wherein
(a) the starting glass is subjected to a heat treatment at a temperature of from 480 to 510° 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 630 to 720° C. in order to form the glass ceramic with lithium disilicate as main crystal phase.

17. Method of using the glass ceramic according to claim 1 as a dental material for the preparation of dental restorations.

18. Method of preparing the dental restorations according to claim 17 , wherein the glass ceramic or a starting glass having the components of the glass ceramic is shaped by pressing or machining to the desired dental restoration.

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

20. Lithium silicate glass ceramic which comprises a trivalent metal oxide selected from Y 2 O 3 , La 2 O 3 , Yb 2 O 3 , Bi 2 O 3 and mixtures thereof, wherein the glass ceramic is substantially free from K 2 O and Na 2 O and has lithium disilicate as a main crystal phase and more than 10 vol.-% lithium disilicate crystals.

Assignees

• Ivoclar Vivadent Ag

Inventors

• Ritzberger Christian
• Apel Elke
• Höland Wolfram
• Rheinberger Volker

Classifications

• C03C4/0021

  for dental use · CPC title

• C03C10/00

  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 title

• C03C3/095 Primary

  containing rare earths · CPC title

• C03C3/097

  containing phosphorus, niobium or tantalum · CPC title

• A61C13/20 Primary

  Methods or devices for soldering, casting, moulding or melting {(A61C13/04, A61C13/081 take precedence)} · CPC title