US4492777A
Expired / Lapsed
US
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Heat treated barium or strontium glass
Assignee: Dentsply Research and Development Corp
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Filing: 1982-11-26
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Granted: 1985-01-08
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Expires: 2002-11-26
Abstract
Abstract The affinity for water of acid-washed barium or strontium glass powder is reduced by a heat treatment.
Inventors
- 👤 Robert K. Denton, Jr.
- 👤 Narayan G. Kumar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 09:47
CPC Classifications
C; C03; C03C; C03C23/00; C03C23/0075; A; A61; A61K; A61K6/00; A61K6/80; A61K6/884; A61K6/887; C08; C08K; C08K3/00; C08K3/40
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
81 words
A single phase barium or strontium glass powder produced by a process that comprises subjecting acid-washed single phase barium or strontium glass powder to an elevated temperature sufficient to cause a significant reduction in the specific surface area of said glass powder, but below the sintering temperature of said glass powder, wherein said glass is hydrophobic as is evidenced by its absorbing less than 0.1 weight percent water, as determined by a differential scanning calorimeter, when exposed to normal ambient conditions.
Claim 2
Dependent Claim
81 words
A single phase barium or strontium glass powder produced by a process that comprises subjecting acid-washed single phase barium or strontium glass powder to an elevated temperature sufficient to cause a significant reduction in the specific surface area of said glass powder, but below the sintering temperature of said glass powder, wherein said glass is hydrophobic as is evidenced by its absorbing less than 0.1 weight percent water, as determined by a differential scanning calorimeter, when exposed to normal ambient conditions.
Claim 3
Dependent Claim
22 words
The glass powder of claim 1 wherein said powder is a barium glass containing up to about 20 mole percent barium oxide.
Claim 4
Dependent Claim
19 words
A resinous dental restorative composition containing a polymerizable composition, a polymerization initiator, and the glass powder of claim 1.
Claim 5
Dependent Claim
19 words
A resinous dental restorative composition containing a polymerizable composition, a polymerization initiator, and the glass powder of claim 2.
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) | 1988-01-08 | 1988-07-09 | 1989-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-08 | 1992-07-09 | 1993-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-08 | 1996-07-09 | 1997-01-08 | $7700.00 | Window Closed / Lapsed |