Patent US3973972A successfully refreshed from Google Patents.
US3973972A
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Glass ceramic as filler in polymerizable dental filling compositions
Assignee: Schott AG
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Filing: 1974-09-11
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Granted: 1976-08-10
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Expires: 1994-09-11
Abstract
Abstract Transparent, colorless, particulate glass ceramic having a low coefficient of expansion, a high absorptivity for X-rays and which is useful in dental filling compositions, has the following ingredients, expressed as percent by weight of oxides: SiO2 40-55%, Al2O3 15-25%, Li2O 3-5%, P2O5 3-10%, MgO 0-3%, ZnO 0-5%, ZrO2 2-7%, Ta2O5 0-7% and La2O3 >12-20%.
Inventors
- 👤 Gerd Muller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:23
CPC Classifications
C; C03; C03C; C03C10/00; C03C10/0018; C03C10/0027; A; A61; A61K; A61K6/00; A61K6/80; A61K6/884; A61K6/887
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
94 words
Particulate colorless, transparent glass ceramic having a particle size of 5-100 microns, having about 30-70% crystallinity by weight, a thermal expansion of less than 20 .sup.. 10.sup. -7 °.sup. -1 (0° - 50° C.) and exhibiting absorption for X-rays, said glass ceramic consisting essentially of, in percent by weight based on oxides: SiO.sub.2 40 - 55
Al.sub.2 O.sub.3 15 - 25
P.sub.2 O.sub.5 3 - 10
Li.sub.2 O [5] 3 - 5
MgO 0 - 3
ZnO 0- 5
ZrO.sub.2 2 - 7
Ta.sub.2 O.sub.5 0 - 7
La.sub.2 O.sub.3 [10] >12 - 20.
Claim 2
Dependent Claim
94 words
Particulate colorless, transparent glass ceramic having a particle size of 5-100 microns, having about 30-70% crystallinity by weight, a thermal expansion of less than 20 .sup.. 10.sup. -7 °.sup. -1 (0° - 50° C.) and exhibiting absorption for X-rays, said glass ceramic consisting essentially of, in percent by weight based on oxides: SiO.sub.2 40 - 55
Al.sub.2 O.sub.3 15 - 25
P.sub.2 O.sub.5 3 - 10
Li.sub.2 O [5] 3 - 5
MgO 0 - 3
ZnO 0- 5
ZrO.sub.2 2 - 7
Ta.sub.2 O.sub.5 0 - 7
La.sub.2 O.sub.3 [10] >12 - 20.
Claim 3
Dependent Claim
21 words
Particulate glass ceramic according to claim 1, containing more than 15% La 2 O 3 to not more than about 20%.
Claim 4
Dependent Claim
60 words
Particulate glass ceramic according to claim 1, having the following composition in percent by weight: SiO.sub.2 40 - 50
Al.sub.2 O.sub.3 16 - 20
Li.sub.2 O 3.3 - 4.7
P.sub.2 O.sub.5 4 - 7
MgO 0 - 2
ZnO 0 - 5
ZrO.sub.2 3 - 6
Ta.sub.2 O.sub.5 2 - 6
La.sub.2 O.sub.3 13 - 18
MgO+ZnO 1 - 7.
Claim 5
Dependent Claim
14 words
Particulate glass ceramic according to claim 3, having a particle size of 5-60 microns.
Claim 6
Dependent Claim
19 words
Particulate glass ceramic according to claim 1, having an X-ray mass absorption coefficient (0.2-0.3A) of about 3 to 7.
Claim 7
Dependent Claim
19 words
Particulate glass ceramic according to claim 4, having an X-ray mass absorption coefficient (0.2-0.3A) of about 3 to 7.
Claim 8
Dependent Claim
14 words
Particulate glass ceramic according to claim 1, having about 40-50 percent crystallinity by weight.
Claim 9
Dependent Claim
14 words
Particulate glass ceramic according to claim 6, having about 40-50 percent crystallinity by weight.
Claim 10
Dependent Claim
20 words
Particulate glass ceramic according to claim 1 having not more than about 17% by weight La 2 O 3 .
Claim 11
Dependent Claim
20 words
Particulate glass ceramic according to claim 2, having not more than about 17% by weight La 2 O 3 .
References Cited (Backward Citations)
US3801344A
Cited
US3808170A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-08-10 | 1980-02-09 | 1980-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-10 | 1984-02-09 | 1984-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-10 | 1988-02-09 | 1988-08-10 | $7700.00 | Window Closed / Lapsed |