Patent US2896086A successfully refreshed from Google Patents.
US5149368A
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Resorbable bioactive calcium phosphate cement
Assignee: Ceramedical Inc
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Filing: 1991-01-10
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Granted: 1992-09-22
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Expires: 2011-01-10
Abstract
Abstract This invention provides a calcium phosphate cement with relatively high surface pH which is very beneficial from the biocompatibility point of view. When calcium phosphate salts react with an acidic reagent to form cement, it normally involves the dissolution and recrystallization process. The acidity of the setting cements depends strongly on the nature of the calcium phosphate salt used, the acidity of the setting reagent, and the reaction rate. The present invention uses high alkaline calcium phosphate ceramics such as tetracalcium phosphate alone or together with calcium phosphate ceramics such as α-tricalcium phosphate as base cementing powder to increase the surface pH of the setting cement.
Inventors
- 👤 Sung-Tsuen Liu
- 👤 Harvey H. Chung
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:00
CPC Classifications
C; C04; C04B; C04B28/00; C04B28/34; C04B28/344; A; A61; A61K; A61K6/00; A61K6/60; A61K6/69; A61K6/80; A61K6/831; A61K6/838; A61K6/849; A61K6/864; A61K6/873; A61L; A61L24/00; A61L24/02; A61L27/00; A61L27/02; A61L27/12; A61F; A61F2310/00; A61F2310/00005; A61F2310/00179; A61F2310/00293; C04B2111/00; C04B2111/00474; C04B2111/00836
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
58 words
A cementitious paste for orthopaedic, dental and maxillofacial applications comprising: a cementing powder of tetracalcium phosphate; a setting reagent consisting essentially of an acidic citrate, wherein the weight ratio of cementing powder to setting reagent lies between 2:1 and 15:1; and sufficient water to form said paste, and which paste, after setting has a pH greater than 5.
Claim 2
Dependent Claim
58 words
A cementitious paste for orthopaedic, dental and maxillofacial applications comprising: a cementing powder of tetracalcium phosphate; a setting reagent consisting essentially of an acidic citrate, wherein the weight ratio of cementing powder to setting reagent lies between 2:1 and 15:1; and sufficient water to form said paste, and which paste, after setting has a pH greater than 5.
Claim 3
Dependent Claim
20 words
The paste of claim 1, wherein said cementing powder is fully decomposed hydroxyapatite which contains tetracalcium phosphate and α-tricalcium phosphate.
Claim 4
Dependent Claim
45 words
The paste of claim 1, wherein said acidic citrate is selected from the group consisting of citric acid, NaH 2 citrate, Na 2 H citrate, KH 2 citrate, K 2 H citrate, (NH 4 ) 2 H citrate and NH 4 H 2 citrate salt.
Claim 5
Dependent Claim
11 words
The paste of claim 1, further comprising soluble pH adjusting reagents.
Claim 6
Dependent Claim
54 words
The paste of claim 4 wherein the soluble pH adjusting reagents are selected from the group consisting of NaOH, KOH, NH 4 OH, Na 3 citrate, K 3 citrate, (NH 4 ) 3 citrate, Na 3 PO 4 , Na 2 HPO 4 , K 3 PO 4 or K 2 HPO 4 .
Claim 7
Dependent Claim
20 words
The paste of claim 5 wherein the soluble pH adjusting reagents are premixed with said cementing powder and setting reagent.
Claim 8
Dependent Claim
16 words
The paste of claim 5 wherein the soluble pH adjusting reagents are dissolved in the water.
Claim 9
Dependent Claim
17 words
The paste of claim 1 further including up to approximately 85% by weight of an inert filler.
Claim 10
Dependent Claim
48 words
The paste of claim 8 wherein the inert filler is selected from the group consisting of α-tricalcium phosphate, calcium phosphate, dicalcium phosphate, octacalcium phosphate, calcium carbonate, calcium sulfate dihydrate, calcium sulfate hemihydrate, calcium sulfate anhydrous, calcium oxide, calcium hydroxide, calcium fluoride, calcium citrate, magnesium oxide, and magnesium hydroxide.
Claim 11
Dependent Claim
21 words
The paste of claim 9 wherein the inert filler is of a particle size ranging from 1 micron to 20 mesh.
Claim 12
Dependent Claim
10 words
The paste of claim 1, wherein said water is saline.
Claim 13
Dependent Claim
14 words
The paste of claim 1 further including up to approximately 30% of an antibiotic.
Claim 14
Dependent Claim
14 words
The paste of claim 1 further including up to approximately 30% bone morphological protein.
Claim 15
Dependent Claim
31 words
The paste of claim 1 wherein the cementing powder contains partially decomposed hydroxyapatite which contains α-tricalcium phosphate and tetracalcium phosphate as a major component and undecomposed hydroxyapatite as a minor component.
References Cited (Backward Citations)
US4668295A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-09-22 | 1996-03-23 | 1996-09-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-09-22 | 2000-03-23 | 2000-09-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-09-22 | 2004-03-23 | 2004-09-22 | $7700.00 | Window Closed / Lapsed |