Glass ceramic having SiO
Glass ceramics having SiO 2 as main crystal phase and precursors thereof are described which are characterized by very good mechanical and optical properties and in particular can be used as restoration material in dentistry.
1. Glass ceramic, which comprises the following components
Component
wt.-%
SiO 2
58.0 to 92.0
Li 2 O
2.0 to 10.0
and comprises SiO 2 as main crystal phase and comprises 5.0 to 50.0 wt.-% SiO 2 as crystal phase,
wherein the glass ceramic is a dental restoration, wherein the dental restoration comprises a bridge, veneer, abutment, partial crown, crown or facet.
2. Glass ceramic according to claim 1 , which comprises 60.0 to 90.0 wt.-% SiO 2 .
3. Glass ceramic according to claim 1 , which comprises 2.8 to 9.0 wt.-% Li 2 O.
4. Glass ceramic according to claim 1 , which comprises 0 to 13.0 wt.-% further alkali metal oxide Me I 2 O.
5. Glass ceramic according to claim 1 , which comprises 0 to 11.0 wt.-% oxide of divalent elements Me II O.
6. Glass ceramic according to claim 1 , which comprises 0 to 10.0 wt.-% oxide of trivalent elements Me III 2 O 3 .
7. Glass ceramic according to claim 1 , which comprises 0 to 21.0 wt.-% further oxide of tetravalent elements Me IV O 2 .
8. Glass ceramic according to claim 1 , which comprises 0 to 7.0 wt.-% P 2 O 5 .
9. Glass ceramic according to claim 1 , which comprises 0 to 6.0 wt.-% further oxide of pentavalent elements Me V 2 O 5 .
10. Glass ceramic according to claim 1 , which comprises 0 to 6.0 wt.-% oxide of hexavalent elements Me VI O 3 .
11. Glass ceramic according to claim 1 , which comprises at least one of the following components in the specified amounts:
Component
wt.-%
Me I 2 O
0 to 13.0
Me II O
0 to 11.0
Me III 2 O 3
0 to 10.0
Me IV O 2
0 to 21.0
P 2 O 5
0 to 7.0
MeV 2 O 5
0 to 6.0
Me VI O 3
0 to 6.0
fluorine
0 to 5.0.
12. Glass ceramic according to claim 1 , which comprises low quartz, cristobalite or a mixture thereof as main crystal phase.
13. Glass ceramic, which comprises the following components
Component
wt.-%
SiO 2
58.0 to 92.0
Li 2 O
2.0 to 10.0
and comprises SiO 2 as main crystal phase and comprises lithium phosphate and/or lithium silicate as further crystal phase,
wherein the glass ceramic is a dental restoration, wherein the dental restoration comprises a bridge, veneer, abutment, partial crown, crown or facet.
14. Process for the preparation of the glass ceramic according to claim 1 , in which a starting glass which comprises the following components
Component
wt.-%
SiO 2
58.0 to 92.0
Li 2 O
2.0 to 10.0
is subjected to at least one heat treatment at a temperature of from 700 to 950° C.
15. Process according to claim 14 , wherein
(a) powder of the starting glass, optionally after the addition of further components, is pressed to form a powder compact, and
(b) the powder compact is subjected to a heat treatment at a temperature of 700 to 950° C.; or
(a′) melt of the starting glass is shaped to form a glass blank, and
(b′) the glass blank is subjected to a heat treatment at a temperature of 700 to 900° C.
16. Process for the preparation of the glass ceramic according to claim 1 , in which the glass ceramic is given the shape of the desired dental restoration by pressing, sintering or machining.
17. Glass ceramic according to claim 1 , wherein the dental restoration comprises a bridge or crown.
18. Glass ceramic according to claim 1 , wherein the dental restoration comprises a bridge.