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US5246889A
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Glass-ceramic and artificial dental crown formed therefrom
Assignee: Hoya Corp
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Filing: 1992-02-26
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Granted: 1993-09-21
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Expires: 2012-02-26
Abstract
Abstract A glass-ceramic which is excellent in mechanical strength, cutting processability and chemical durability and suitable for the production of an artificial dental crown and a mold, the glass-ceramic containing, by weight percentage, 2 to 17% of CaO, 0 to 5% of K 2 O, 0 to 4% of Na 2 O, the total content of K 2 O and Na 2 O being 0.5-7%, 15 to 35% of MgO, 30 to 49% of SiO 2 , 2 to 15% of ZrO 2 and not more than 14% (calculated as F) of fluorine, and having a zirconia crystal and a mica crystal precipitated.
Inventors
- 👤 Tomoko Kasuga
- 👤 Toshihiro Kasuga
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:00
CPC Classifications
C; C03; C03C; C03C10/00; C03C10/0036; C03C10/0045; A; A61; A61K; A61K6/00; A61K6/80; A61K6/802; A61K6/807; A61K6/816; A61K6/818; A61K6/824; A61K6/831; A61K6/833; C03C10/16
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
61 words
A glass-ceramic containing, by weight percentage, ______________________________________
CaO 2-17%,
K.sub.2 O 0-5%
Na.sub.2 O 0-4%
______________________________________ the total content of K 2 O and Na 2 O being 0.5-7%, ______________________________________
MgO 15-35%
SiO.sub.2 30-49%
Al.sub.2 O.sub.3 5-30%
ZrO.sub.2 2-15%, and
fluorine (calculated as F)
not more than 14%,
______________________________________ and having at least a zirconia crystal and a mica crystal precipitated.
Claim 2
Dependent Claim
61 words
A glass-ceramic containing, by weight percentage, ______________________________________
CaO 2-17%,
K.sub.2 O 0-5%
Na.sub.2 O 0-4%
______________________________________ the total content of K 2 O and Na 2 O being 0.5-7%, ______________________________________
MgO 15-35%
SiO.sub.2 30-49%
Al.sub.2 O.sub.3 5-30%
ZrO.sub.2 2-15%, and
fluorine (calculated as F)
not more than 14%,
______________________________________ and having at least a zirconia crystal and a mica crystal precipitated.
Claim 3
Dependent Claim
20 words
A glass-ceramic according to claim 1, wherein the fluorine is contained in an amount of 1.5 to 14% by weight.
Claim 4
Dependent Claim
139 words
A glass-ceramic according to claim 1, wherein the CaO is contained in an amount of 5 to 15% by weight, the K 2 O is contained in an amount of 1 to 3.5% by weight, the Na 2 O is contained in an amount of 0.5 to 1.8% by weight, the total amount of the K 2 O and the Na 2 O is 1.5 to 5.3% by weight, MgO is contained in an amount of 19 to 30% by weight, the SiO 2 is contained in an amount of 40 to 49% by weight, the Al 2 O 3 is contained in an amount of 7 to 17% by weight, the ZrO 2 is contained in an amount of 3 to 12% by weight, and the fluorine is contained in an amount of 7 to 14% by weight.
Claim 5
Dependent Claim
41 words
A glass-ceramic according to claim 1, which further contains not more than 5% by weight of at least one oxide selected from SrO, TiO 2 , Nb 2 O 5 , Ta 2 O 5 and Y 2 O 3 .
Claim 6
Dependent Claim
35 words
A glass-ceramic according to claim 1, which further has at least one precipitated crystal selected from an enstatite crystal, an akermanite crystal, a diopside crystal, an anorthite crystal, a richterite crystal and a forsterite crystal.
Claim 7
Dependent Claim
14 words
An artificial dental crown, which is formed from the glass-ceramic recited in claim 1.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-09-20 | 1997-03-22 | 1997-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-09-20 | 2001-03-22 | 2001-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-09-20 | 2005-03-22 | 2005-09-21 | $7700.00 | Window Closed / Lapsed |