US4797431A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Glass/poly(carboxylic acid) cement compositions
Assignee: Dentsply Ltd
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Filing: 1987-04-06
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Granted: 1989-01-10
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Expires: 2007-04-06
Abstract
Abstract A process for producing a radiopaque cement comprises reacting a polymer containing free carboxyl groups (generally a homo or copolymer of acrylic acid) with a particulate acid-leachable source of polyvalent metal ions (such as an acid-leachable glass) in the presence of water and strontium fluoride.
Inventors
- 👤 Richard W. Billington
- 👤 Jill A. Williams
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:06
CPC Classifications
A; A61; A61K; A61K6/00; A61K6/80; A61K6/884; A61K6/887; A61K6/889
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
106 words
A substantially optically translucent dental restorative material comprising a polymerized matrix containing an acid or an alkali-leachable source of polyvalent metal ions, said matrix consisting essentially of a homopolymer or copolymer of acrylic acid having a molecular weight of 20,000 to 125,000 and said leachable source consisting essentially of by weight about 15-33% SrF 2 , not more than 25% CaO, 28-38% Al 2 O 3 , 25-30% SiO 2 , 0-9% P 2 O 5 , the ratio of said homopolymer to said leachable source being between 0.15 to 1 and 0.5 to 1 whereby the strontium fluoride provides essentially all of the radiopaque properties.
Claim 2
Dependent Claim
106 words
A substantially optically translucent dental restorative material comprising a polymerized matrix containing an acid or an alkali-leachable source of polyvalent metal ions, said matrix consisting essentially of a homopolymer or copolymer of acrylic acid having a molecular weight of 20,000 to 125,000 and said leachable source consisting essentially of by weight about 15-33% SrF 2 , not more than 25% CaO, 28-38% Al 2 O 3 , 25-30% SiO 2 , 0-9% P 2 O 5 , the ratio of said homopolymer to said leachable source being between 0.15 to 1 and 0.5 to 1 whereby the strontium fluoride provides essentially all of the radiopaque properties.
Claim 3
Dependent Claim
22 words
The dental restorative material of claim 1 in which said homopolymer comprises ethylenically unsaturated compounds, said leachable source comprises a particulate filler.
Claim 4
Dependent Claim
27 words
The dental restorative material of claim 2 in which the polymerized matrix is formed from a composite composition comprising ethylenically unsaturated compounds, particulate filler and polymerization initiator.
Claim 5
Dependent Claim
12 words
The restorative material of claim 3 which is a polyacrylate dental cement.
Claim 6
Dependent Claim
21 words
A structure as claimed in claim 1 having a radiopacity of at least 1.0 mm of aluminium per mm of structure.
Claim 7
Dependent Claim
20 words
A structure as claimed in claim 1 having a radiopacity of at least 1.5 mm aluminium per mm of structure.
Claim 8
Dependent Claim
20 words
A structure as claimed in claim 1 having a radiopacity of at least 2.0 mm aluminium per mm of structure.
Claim 9
Dependent Claim
14 words
The homopolymer of claim 1 having a molecular weight of from 35,000 to 70,000.
References Cited (Backward Citations)
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Cited
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-01-10 | 1992-07-11 | 1993-01-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-01-10 | 1996-07-11 | 1997-01-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-01-10 | 2000-07-11 | 2001-01-10 | $7700.00 | Window Closed / Lapsed |