US4808228A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Glass ionomer cement powder
Assignee: 3M Co
•
Filing: 1987-02-20
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Granted: 1989-02-28
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Expires: 2007-02-20
Abstract
Abstract Carboxylic acids are comminuted with fluoroaluminosilicate glass frit to form a cement powder containing carboxylate salt. The cement powder can be used to prepare glass ionomer dental cements with extended work times.
Inventors
- 👤 Ronald M. Randklev
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 22:46
CPC Classifications
A; A61; A61K; A61K6/00; A61K6/50; A61K6/54; A61K6/30; A61K6/80; A61K6/884; A61K6/887; A61K6/889
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
67 words
A process for making a dental cement powder, comprising the step of comminuting together fluoroaluminosilicate glass and carboxylic acid under sufficiently vigorous, substantially anhydrous pulverization conditions to form carboxylate salt in said powder wherein the presence of said salt in said powder is detectable by a diffuse reflectance Fourier transform infrared spectrum that exhibits distinct absorption peaks between 1610-1550 cm - or at 1400 cm - .
Claim 2
Dependent Claim
67 words
A process for making a dental cement powder, comprising the step of comminuting together fluoroaluminosilicate glass and carboxylic acid under sufficiently vigorous, substantially anhydrous pulverization conditions to form carboxylate salt in said powder wherein the presence of said salt in said powder is detectable by a diffuse reflectance Fourier transform infrared spectrum that exhibits distinct absorption peaks between 1610-1550 cm - or at 1400 cm - .
Claim 3
Dependent Claim
17 words
A process according to claim 1, wherein said pulverization conditions comprise impact comminution means that employ media.
Claim 4
Dependent Claim
20 words
A process according to claim 2, wherein said impact comminution means comprise a tumbling mill, attrition mill or vibration mill.
Claim 5
Dependent Claim
15 words
A process according to claim 2, wherein said impact comminution means comprise a ball mill.
Claim 6
Dependent Claim
19 words
A process according to claim 1, wherein said carboxylic acid comprises a solid mono-, di-, tri-, or tetra-carboxylic acid.
Claim 7
Dependent Claim
13 words
A process according to claim 1, wherein said carboxylic acid comprises tartaric acid.
Claim 8
Dependent Claim
13 words
A process according to claim 6, wherein said tartaric acid comprises d-tartaric acid.
Claim 9
Dependent Claim
37 words
A process according to claim 1, wherein the amount of said carboxylic acid is sufficient to extend by at least 15 seconds the work time of a cement made by combining said glass with aqueous poly(carboxylic acid).
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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) | 1992-02-28 | 1992-08-29 | 1993-02-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-28 | 1996-08-29 | 1997-02-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-28 | 2000-08-29 | 2001-02-28 | $7700.00 | Window Closed / Lapsed |