US4747876A
Expired / Lapsed
US
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Dental crown material
Assignee: Olympus Corp
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Filing: 1986-09-15
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Granted: 1988-05-31
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Expires: 2006-09-15
Abstract
Abstract A dental crown formed of a dental crown material comprising crystallized glass containing 40 to 45% by weight of SiO 2 , 11 to 15% by weight of Al 2 O 3 , 16 to 23% by weight of MgO, 6.5 to 8% by weight of F, 4.0 to 7.0% by weight of Na 2 O, 5 to 9% by weight of Li 2 O, not more than 1% by weight of TiO 2 , 2 to 4% by weight of ZrO 2 , and at least one oxide selected from the group consisting of Fe 2 O 3 , MnO, CeO 2 and NiO, and having a bending strength of at least 2000 Kg/cm 2 .
Inventors
- 👤 Yasuharu Hakamatsuka
- 👤 Kazuhiro Watanabe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 10:51
CPC Classifications
C; C03; C03C; C03C10/00; C03C10/16; A; A61; A61K; A61K6/00; A61K6/70; A61K6/78; A61K6/80; A61K6/802; A61K6/807; A61K6/816; A61K6/818; A61K6/822; A61K6/831; A61K6/836
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
117 words
A dental crown formed of a dental crown material comprising crystallized glass containing 40 to 45% by weight of SiO 2 , 11 to 15% by weight of Al 2 O 3 , 16 to 23% by weight of MgO, 6.5 to 8% by weight of F, 4.0 to 7.0% by weight of Na 2 O, 5 to 9% by weight of Li 2 O, not more than 1% by weight of TiO 2 , 2 to 4% by weight of ZrO 2 , and at least one oxide selected from the group consisting of Fe 2 O 3 , MnO, CeO 2 and NiO, and having a bending strength of at least 2000 Kg/cm 2 .
Claim 2
Dependent Claim
117 words
A dental crown formed of a dental crown material comprising crystallized glass containing 40 to 45% by weight of SiO 2 , 11 to 15% by weight of Al 2 O 3 , 16 to 23% by weight of MgO, 6.5 to 8% by weight of F, 4.0 to 7.0% by weight of Na 2 O, 5 to 9% by weight of Li 2 O, not more than 1% by weight of TiO 2 , 2 to 4% by weight of ZrO 2 , and at least one oxide selected from the group consisting of Fe 2 O 3 , MnO, CeO 2 and NiO, and having a bending strength of at least 2000 Kg/cm 2 .
Claim 3
Dependent Claim
24 words
The crown according to claim 1 wherein the crystallized glass contains a mica crystal phase, a β-eucryptite crystal phase, and a β-spodumene crystal phase.
Claim 4
Dependent Claim
47 words
The crown according to claim 1 wherein Fe 2 O 3 is in an amount up to 0.5%, said MnO is in an amount up to 0.05%, said NiO is in an amount up to 0.1% and said CeO 2 is in an amount up to 0.1%.
Claim 5
Dependent Claim
46 words
The crown according to claim 2 wherein Fe 2 O 3 is in an amount up to 0.5%, said MnO is in an amount up to 0.05%, said NiO is in an amount up to 0.1% and said CeO 2 is in amount up to 0.1%.
Claim 6
Dependent Claim
19 words
The crown according to claim 4, wherein the crown material further comprises 1 to 7% by weight of ZnO.
Claim 7
Dependent Claim
19 words
The crown according to claim 1 which contains Fe 2 O 3 , MnO, NiO and CeO 2 .
Claim 8
Dependent Claim
19 words
The crown according to claim 5 which contains Fe 2 O 3 , MnO, NiO and CeO 2 .
Claim 9
Dependent Claim
23 words
The crown according to claim 1 which contains 0.1% Fe 2 O 3 , 0.01% MnO, 0.005% NiO and 0.1% CeO 2 .
Claim 10
Dependent Claim
23 words
The crown according to claim 5 which contains 0.1% Fe 2 O 3 , 0.1% MnO, 0.005% NiO and 0.1% CeO 2 .
Claim 11
Dependent Claim
40 words
The crown according to claim 8 which contains 42% SiO 2 , 12% Al 2 O 3 , 18% MgO, 3% ZnO, 4.4% Na 2 O, 8.1% Li 2 O, 1% TiO 2 , 2% ZrO 2 and 7.5% F.
Claim 12
Dependent Claim
40 words
The crown according to claim 9 which contains 42% SiO 2 , 12% Al 2 O 3 , 18% MgO, 3% ZnO, 4.4% Na 2 O, 8.1% Li 2 O, 1% TiO 2 , 2% ZrO 2 and 7.5% F.
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) | 1991-05-31 | 1991-11-30 | 1992-05-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-05-31 | 1995-11-30 | 1996-05-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-05-31 | 1999-11-30 | 2000-05-31 | $7700.00 | Window Closed / Lapsed |