US3966479A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dental investment material
Assignee: Dentsply Research and Development Corp
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Filing: 1973-02-27
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Granted: 1976-06-29
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Expires: 1993-02-27
Abstract
Abstract A dental investment material comprising a modified calcium sulfate which when hydrated possesses unique fracture properties of particular advantage when the material is used as a composition for making molds particularly for use in the lost wax process.
Inventors
- 👤 Francis Frederick Koblitz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:42
CPC Classifications
C; C04; C04B; C04B28/00; C04B28/14
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
109 words
A microscopically foraminous solid dental molding composition having a fracture strength under compression of from between about 100psi to about 500psi comprising uniformly distributed therethrough about 30 to 45% by weight of a substantially completely hydrated calcined gypsum, about 30 to 55% by weight of chemically uncombined water, about 5 to 20% by weight of an extender capable of maintaining the chemically uncombined water evenly distributed throughout the solid, wherein said extender is selected from the group consisting of diatomaceous earth or perlite; and about 3 to 10% by weight of a water swollen glutinous organic binder capable of enhancing the adherence of the hydrated gypsum to the extender.
Claim 2
Dependent Claim
109 words
A microscopically foraminous solid dental molding composition having a fracture strength under compression of from between about 100psi to about 500psi comprising uniformly distributed therethrough about 30 to 45% by weight of a substantially completely hydrated calcined gypsum, about 30 to 55% by weight of chemically uncombined water, about 5 to 20% by weight of an extender capable of maintaining the chemically uncombined water evenly distributed throughout the solid, wherein said extender is selected from the group consisting of diatomaceous earth or perlite; and about 3 to 10% by weight of a water swollen glutinous organic binder capable of enhancing the adherence of the hydrated gypsum to the extender.
Claim 3
Dependent Claim
13 words
The invention of claim 1 wherein the binder is cornstarch or carboxymethyl cellulose.
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) | 1979-06-29 | 1979-12-29 | 1980-06-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-06-29 | 1983-12-29 | 1984-06-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-06-29 | 1987-12-29 | 1988-06-29 | $7700.00 | Window Closed / Lapsed |