US5470803A
Expired / Lapsed
US
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Method for the preparation of carbonated hydroxyapatite compositions
Assignee: Abonetics Ltd
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Filing: 1994-05-18
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Granted: 1995-11-28
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Expires: 2014-05-18
Abstract
Abstract A method for the preparation of a carbonated hydroxyapatite composition which has a density of at least 95% of the theoretical density, which method comprises sintering at substantially atmosphere pressure a green carbonated hydroxyapatite composition containing up to 20% by weight of CO 3 2- ions and having a green density of from 25 to 60% of the theoretical density at a temperature in the range of from 750° to 1450° C. in carbon dioxide containing from 0.001 to 0.10 grams of water per liter of gas, the sintering temperature being selected within the above range and the green composition being sintered for a period of time sufficient to cause the green composition to densify to at least 95% of the theoretical density.
Inventors
- 👤 William Bonfield
- 👤 Serena M. Best
- 👤 Jake E. Barralet
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 04:56
CPC Classifications
A; A61; A61L; A61L27/00; A61L27/02; A61L27/12; C; C04; C04B; C04B35/00; C04B35/01; C04B35/447; A61F; A61F2310/00; A61F2310/00005; A61F2310/00179; A61F2310/00293
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
132 words
A method for the preparation of a carbonated hydroxyapatite composition which has a density of at least 95% of the theoretical density, which method comprises sintering at substantially atmosphere pressure a dry green carbonated hydroxyapatite compact which contains up to 20% by weight of CO 3 ions but which does not contain any binder and which has a green density of from 25 to 60% of the theoretical density at a temperature in the range of from 750° to 1450° C. in carbon dioxide containing from 0.001 to 0.10 grams of water per liter of gas, the sintering temperature being selected within the above range and the green compact being sintered for a period of time sufficient to cause the green compact to densify to at least 95% of the theoretical density.
Claim 2
Independent Claim
132 words
A method for the preparation of a carbonated hydroxyapatite composition which has a density of at least 95% of the theoretical density, which method comprises sintering at substantially atmosphere pressure a dry green carbonated hydroxyapatite compact which contains up to 20% by weight of CO 3 ions but which does not contain any binder and which has a green density of from 25 to 60% of the theoretical density at a temperature in the range of from 750° to 1450° C. in carbon dioxide containing from 0.001 to 0.10 grams of water per liter of gas, the sintering temperature being selected within the above range and the green compact being sintered for a period of time sufficient to cause the green compact to densify to at least 95% of the theoretical density.
Claim 3
Dependent Claim
21 words
Method as claimed in claim 1 wherein the green composition has a density of 30 to 40% of the theoretical density.
Claim 4
Dependent Claim
20 words
Method as claimed in claim 1 wherein the sintering temperature is in the range of from 750° to 1150° C.
Claim 5
Dependent Claim
22 words
Method as claimed in claim 1 wherein the carbon dioxide contains from 0.01 to 0.02 grams of water per liter of gas.
Claim 6
Dependent Claim
22 words
Method as claimed in claim 1 wherein the sintering is carried out for a period of time of up to 24 hours.
Claim 7
Dependent Claim
22 words
Method as claimed in claim 5 wherein the sintering is carried out for a period of time of up to 4 hours.
Claim 8
Dependent Claim
23 words
Method as claimed in claim 1 wherein the green carbonated hydroxyapatite composition has a carbonate content of from 3 to 10% by weight.
Claim 9
Dependent Claim
23 words
Method as claimed in claim 1 wherein the carbonated hydroxyapatite composition comprises from 4 to 6% by weight of CO 3 2- ions.
Claim 10
Dependent Claim
22 words
Method as claimed in claim 1 wherein the carbonated hydroxyapatite has a density of from 98% to 100% of the theoretical density.
Claim 11
Dependent Claim
12 words
Method as claimed in claim 9 wherein the carbonated hydroxyapatite is translucent.
Claim 12
Independent Claim
102 words
A method for the preparation of a carbonated hydroxyapatite composition which has a density of at least 95% of the theoretical density, which method comprises sintering at substantially atmosphere pressure a dry green carbonated hydroxyapatite compact which contains up to 20% by weight of CO 3 ions but which does not contain any binder at a temperature in the range of from 1000° to 1450° C. in carbon dioxide containing from 0.001 to 0.10 grams of water per liter of gas, for a period of time sufficient to cause the green compact to densify to at least 95% of the theoretical density.
Claim 13
Independent Claim
102 words
A method for the preparation of a carbonated hydroxyapatite composition which has a density of at least 95% of the theoretical density, which method comprises sintering at substantially atmosphere pressure a dry green carbonated hydroxyapatite compact which contains up to 20% by weight of CO 3 ions but which does not contain any binder at a temperature in the range of from 1000° to 1450° C. in carbon dioxide containing from 0.001 to 0.10 grams of water per liter of gas, for a period of time sufficient to cause the green compact to densify to at least 95% of the theoretical density.
Claim 14
Dependent Claim
20 words
Method as claimed in claim 11 wherein the sintering temperature is in the range of from 1100° to 1300° C.
Claim 15
Dependent Claim
22 words
Method as claimed in claim 11 wherein the carbon dioxide contains from 0.01 to 0.02 grams of water per liter of gas.
Claim 16
Dependent Claim
23 words
Method as claimed in claim 11 wherein the carbonated hydroxyapatite composition comprises from 4 to 6% by weight of CO 3 2- ions.
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) | 1998-11-27 | 1999-05-29 | 1999-11-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-11-27 | 2003-05-29 | 2003-11-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-11-27 | 2007-05-29 | 2007-11-28 | $7700.00 | Window Closed / Lapsed |