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US5545254A Expired / Lapsed US ⏱️ 0.0 years remaining

Calcium phosphate hydroxyapatite precursor and methods for making and using the same

Assignee: American Dental Association
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Filing: 1994-12-09
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Granted: 1996-08-13
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Expires: 2014-12-09
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Abstract

Abstract Calcium phosphate compositions that are particularly useful and unique as orthopedic and dental cements and remineralizers, as well as methods and kits for their use, and the resulting products are disclosed. The compositions comprise tetracalcium phosphate which has been prepared from a mixture with a calcium to phosphorous ratio of less than 2, or prepared and maintained under substantially anhydrous conditions prior to use or, preferably, both. The novel compositions are converted substantially to hydroxyapatite upon setting, are substantially gradually resorbable and replaced by bone when implanted in contact with living bony tissue, and offer distinct advantages in terms of cement strength, setting time and reliability and other properties.

Inventors

  • 👤 Laurence C. Chow
  • 👤 Shozo Takagi

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-23 01:46
CPC Classifications
A; A61; A61Q; A61Q11/00; A61K; A61K6/00; A61K6/50; A61K6/54; A61K6/80; A61K6/831; A61K6/838; A61K6/849; A61K6/864; A61K6/876; A61K8/00; A61K8/18; A61K8/19; A61K8/24; A61L; A61L24/00; A61L24/02; A61L27/00; A61L27/02; A61L27/12; A61F; A61F2310/00; A61F2310/00005; A61F2310/00179; A61F2310/00293

Claims Analysis

Total Claims: 4
Claim 1
Independent Claim 39 words
An improved method for preparing a tetracalcium phosphate based calcium phosphate-containing composition comprising combining tetracalcium phosphate and at least one other sparingly soluble calcium phosphate, wherein the improvement comprises employing tetracalcium phosphate which is substantially free of calcium oxide.
Claim 2
Dependent Claim 39 words
An improved method for preparing a tetracalcium phosphate based calcium phosphate-containing composition comprising combining tetracalcium phosphate and at least one other sparingly soluble calcium phosphate, wherein the improvement comprises employing tetracalcium phosphate which is substantially free of calcium oxide.
Claim 3
Dependent Claim 43 words
An improved method for preparing a tetracalcium phosphate based calcium phosphate-containing composition comprising combining tetracalcium phosphate and at least one other sparingly soluble calcium phosphate compound wherein the improvement comprises employing tetracalcium phosphate which is substantially free of surface hydroxyapatite prior to use.
Claim 4
Dependent Claim 43 words
An improved method for preparing a tetracalcium phosphate based calcium phosphate-containing composition comprising combining tetracalcium phosphate and at least one other sparingly soluble calcium phosphate compound wherein the improvement comprises employing tetracalcium phosphate which is substantially free of surface hydroxyapatite prior to use.

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1999-08-13 2000-02-12 2000-08-13 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 2003-08-13 2004-02-12 2004-08-13 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2007-08-13 2008-02-12 2008-08-13 $7700.00 Window Closed / Lapsed

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