US5522893A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Calcium phosphate hydroxyapatite precursor and methods for making and using the same
Assignee: American Dental Association
•
Filing: 1993-03-12
•
Granted: 1996-06-04
•
Expires: 2013-03-12
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: 79
Claim 1
Independent Claim
64 words
A calcium phosphate-containing composition, which self-hardens substantially to hydroxyapatite at ambient temperature when in contact with an aqueous medium, comprising tetracalcium phosphate and at least one other sparingly soluble calcium phosphate compound, wherein the tetracalcium phosphate is prepared from a starting mixture of one or more sources of calcium, phosphorous and oxygen which mixture has a calcium to phosphorous ratio of less than 2.
Claim 2
Dependent Claim
64 words
A calcium phosphate-containing composition, which self-hardens substantially to hydroxyapatite at ambient temperature when in contact with an aqueous medium, comprising tetracalcium phosphate and at least one other sparingly soluble calcium phosphate compound, wherein the tetracalcium phosphate is prepared from a starting mixture of one or more sources of calcium, phosphorous and oxygen which mixture has a calcium to phosphorous ratio of less than 2.
Claim 3
Dependent Claim
40 words
A calcium phosphate-containing composition as in claim 1 wherein the other sparingly soluble calcium phosphate is selected from the group consisting of monocalcium phosphate, dicalcium phosphate anhydrous, dicalcium phosphate dihydrate, alpha-tricalcium phosphate, beta-tricalcium phosphate, octacalcium phosphate, and amorphous calcium phosphate.
Claim 4
Dependent Claim
29 words
A calcium phosphate-containing composition as in claim 2, wherein the other sparingly soluble calcium phosphate is selected from the group consisting of dicalcium phosphate anhydrous and dicalcium phosphate dihydrate.
Claim 5
Dependent Claim
62 words
A calcium phosphate-containing composition, which self-hardens substantially to hydroxyapatite at ambient temperature when in contact with an aqueous medium, comprising tetracalcium phosphate and at least one other sparingly soluble calcium phosphate compound, wherein the tetracalcium phosphate is prepared and maintained under substantially anhydrous conditions prior to its contact with the aqueous medium in combination with the other sparingly soluble calcium phosphate compound.
Claim 6
Dependent Claim
62 words
A calcium phosphate-containing composition, which self-hardens substantially to hydroxyapatite at ambient temperature when in contact with an aqueous medium, comprising tetracalcium phosphate and at least one other sparingly soluble calcium phosphate compound, wherein the tetracalcium phosphate is prepared and maintained under substantially anhydrous conditions prior to its contact with the aqueous medium in combination with the other sparingly soluble calcium phosphate compound.
Claim 7
Dependent Claim
39 words
A calcium phosphate-containing composition as in claim 4 wherein the sparingly soluble calcium phosphate is selected from the group consisting of monocalcium phosphate, dicalcium phosphate anhydrous, dicalcium phosphate dihydrate, alpha-tricalcium phosphate, beta-tricalcium phosphate, octacalcium phosphate, and amorphous calcium phosphate.
Claim 8
Dependent Claim
29 words
A calcium phosphate-containing composition as in claim 5, wherein the other sparingly soluble calcium phosphate is selected from the group consisting of dicalcium phosphate anhydrous and dicalcium phosphate dihydrate.
Claim 9
Dependent Claim
41 words
A calcium phosphate-containing composition, which self-hardens substantially to hydroxyapatite at ambient temperature when in contact with an aqueous medium, comprising tetracalcium phosphate and at least one other sparingly soluble calcium phosphate compound, wherein the tetracalcium phosphate is free of calcium oxide.
Claim 10
Dependent Claim
41 words
A calcium phosphate-containing composition, which self-hardens substantially to hydroxyapatite at ambient temperature when in contact with an aqueous medium, comprising tetracalcium phosphate and at least one other sparingly soluble calcium phosphate compound, wherein the tetracalcium phosphate is free of calcium oxide.
Claim 11
Dependent Claim
29 words
A calcium phosphate-containing composition as in claim 7, wherein the other sparingly soluble calcium phosphate is selected from the group consisting of dicalcium phosphate anhydrous and dicalcium phosphate dihydrate.
Claim 12
Dependent Claim
44 words
A calcium phosphate-containing composition, which self-hardens substantially to hydroxyapatite at ambient temperature when in contact with an aqueous medium, comprising tetracalcium phosphate and at least one other sparingly soluble calcium phosphate compound, wherein the tetracalcium phosphate is free of surface hydroxyapatite prior to use.
Claim 13
Dependent Claim
44 words
A calcium phosphate-containing composition, which self-hardens substantially to hydroxyapatite at ambient temperature when in contact with an aqueous medium, comprising tetracalcium phosphate and at least one other sparingly soluble calcium phosphate compound, wherein the tetracalcium phosphate is free of surface hydroxyapatite prior to use.
Claim 14
Dependent Claim
29 words
A calcium phosphate-containing composition as in claim 9, wherein the other sparingly soluble calcium phosphate is selected from the group consisting of dicalcium phosphate anhydrous and dicalcium phosphate dihydrate.
Claim 15
Dependent Claim
94 words
A calcium phosphate-containing composition, which self-hardens substantially to hydroxyapatite at ambient temperature when in contact with an aqueous medium, comprising tetracalcium phosphate and at least one other sparingly soluble calcium phosphate compound, wherein the tetracalcium phosphate is prepared from a starting mixture of one or more sources of calcium, phosphorous and oxygen which has a calcium to phosphorous ratio of less than 2; and wherein the tetracalcium phosphate is prepared and maintained under substantially anhydrous conditions prior to its contact with the aqueous medium in combination with the other sparingly soluble calcium phosphate compound.
Claim 16
Dependent Claim
94 words
A calcium phosphate-containing composition, which self-hardens substantially to hydroxyapatite at ambient temperature when in contact with an aqueous medium, comprising tetracalcium phosphate and at least one other sparingly soluble calcium phosphate compound, wherein the tetracalcium phosphate is prepared from a starting mixture of one or more sources of calcium, phosphorous and oxygen which has a calcium to phosphorous ratio of less than 2; and wherein the tetracalcium phosphate is prepared and maintained under substantially anhydrous conditions prior to its contact with the aqueous medium in combination with the other sparingly soluble calcium phosphate compound.
Claim 17
Dependent Claim
29 words
A calcium phosphate-containing composition as in claim 11, wherein the other sparingly soluble calcium phosphate is selected from the group consisting of dicalcium phosphate anhydrous and dicalcium phosphate dihydrate.
Claim 18
Dependent Claim
30 words
The composition of claim 11 further comprising up to approximately 10% by weight of additional calcium or phosphate-containing compounds in an amount sufficient to alter the pH of the composition.
Claim 19
Dependent Claim
28 words
The composition of claim 11 further comprising an additive selected from the group consisting of proteins, medicaments, filler materials, crystal growth adjusters, viscosity modifiers and pore forming agents.
Claim 20
Dependent Claim
70 words
A calcium phosphate-containing composition, which self-hardens substantially to hydroxyapatite at ambient temperature when in contact with an aqueous medium, comprising tetracalcium phosphate and at least one other sparingly soluble calcium phosphate compound, wherein the tetracalcium phosphate is comminuted tetracalcium phosphate having an average particle size for at least about 10% of the particles of about 15μ or less and which is free of both impurity calcium oxide and surface hydroxyapatite.
Claim 21
Dependent Claim
70 words
A calcium phosphate-containing composition, which self-hardens substantially to hydroxyapatite at ambient temperature when in contact with an aqueous medium, comprising tetracalcium phosphate and at least one other sparingly soluble calcium phosphate compound, wherein the tetracalcium phosphate is comminuted tetracalcium phosphate having an average particle size for at least about 10% of the particles of about 15μ or less and which is free of both impurity calcium oxide and surface hydroxyapatite.
Claim 22
Dependent Claim
29 words
A calcium phosphate-containing composition as in claim 15, wherein the other sparingly soluble calcium phosphate is selected from the group consisting of dicalcium phosphate anhydrous and dicalcium phosphate dihydrate.
Claim 23
Dependent Claim
14 words
A dental restorative having as a calcium phosphate component the composition of claim 1.
Claim 24
Dependent Claim
14 words
A remineralizing dentifrice comprising as a calcium phosphate abrasive the composition of claim 1.
Claim 25
Dependent Claim
15 words
A remineralizing chewing gum comprising as a calcium phosphate additive the composition of claim 1.
Claim 26
Dependent Claim
12 words
The dental restorative of claim 17, wherein the aqueous medium is saliva.
Claim 27
Dependent Claim
14 words
A dental restorative having as a calcium phosphate component the composition of claim 4.
Claim 28
Dependent Claim
14 words
A remineralizing dentifrice comprising as a calcium phosphate abrasive the composition of claim 4.
Claim 29
Dependent Claim
15 words
A remineralizing chewing gum comprising as a calcium phosphate additive the composition of claim 4.
Claim 30
Dependent Claim
12 words
The dental restorative of claim 21 wherein the aqueous medium is saliva.
Claim 31
Dependent Claim
15 words
A dental desensitization agent having as a calcium phosphate component the composition of claim 1.
Claim 32
Dependent Claim
15 words
A dental desensitization agent having as a calcium phosphate component the composition of claim 4.
Claim 33
Dependent Claim
17 words
A calcium phosphate tissue substitute precursor having as a calcium phosphate component the composition of claim 1.
Claim 34
Dependent Claim
17 words
A calcium phosphate tissue substitute precursor having as a calcium phosphate component the composition of claim 4.
Claim 35
Dependent Claim
65 words
A calcium phosphate bone cement which self-hardens substantially at ambient temperature and is substantially resorbable when implanted in contact with living bone comprising tetracalcium phosphate and at least one other sparingly soluble calcium phosphate wherein the tetracalcium phosphate is prepared from a starting mixture of one or more sources of calcium, phosphorous and oxygen which has a calcium to phosphorous ratio of less than 2.
Claim 36
Dependent Claim
65 words
A calcium phosphate bone cement which self-hardens substantially at ambient temperature and is substantially resorbable when implanted in contact with living bone comprising tetracalcium phosphate and at least one other sparingly soluble calcium phosphate wherein the tetracalcium phosphate is prepared from a starting mixture of one or more sources of calcium, phosphorous and oxygen which has a calcium to phosphorous ratio of less than 2.
Claim 37
Dependent Claim
26 words
The cement of claim 29, wherein the other sparingly soluble calcium phosphate is selected from the group consisting of dicalcium phosphate dihydrate and dicalcium phosphate anhydrous.
Claim 38
Dependent Claim
64 words
A calcium phosphate bone cement which self-hardens substantially at ambient temperature and is substantially resorbable when implanted in contact with living bone comprising tetracalcium phosphate and at least one other sparingly soluble calcium phosphate wherein the tetracalcium phosphate is prepared and maintained under substantially anhydrous conditions prior to its contact with the aqueous medium in combination with the other sparingly soluble calcium phosphate compound.
Claim 39
Dependent Claim
64 words
A calcium phosphate bone cement which self-hardens substantially at ambient temperature and is substantially resorbable when implanted in contact with living bone comprising tetracalcium phosphate and at least one other sparingly soluble calcium phosphate wherein the tetracalcium phosphate is prepared and maintained under substantially anhydrous conditions prior to its contact with the aqueous medium in combination with the other sparingly soluble calcium phosphate compound.
Claim 40
Dependent Claim
26 words
The cement of claim 31, wherein the other sparingly soluble calcium phosphate is selected from the group consisting of dicalcium phosphate dihydrate and dicalcium phosphate anhydrous.
Claim 41
Dependent Claim
96 words
A calcium phosphate bone cement which self-hardens substantially at ambient temperature and is substantially resorbable when implanted in contact with living bone comprising tetracalcium phosphate and at least one other sparingly soluble calcium phosphate wherein the tetracalcium phosphate is prepared from a starting mixture of one or more sources of calcium, phosphorous and oxygen which has a calcium to phosphorous ratio of less than 2; and wherein the tetracalcium phosphate is prepared and maintained under substantially anhydrous conditions prior to its contact with the aqueous medium in combination with the other sparingly soluble calcium phosphate compound.
Claim 42
Dependent Claim
96 words
A calcium phosphate bone cement which self-hardens substantially at ambient temperature and is substantially resorbable when implanted in contact with living bone comprising tetracalcium phosphate and at least one other sparingly soluble calcium phosphate wherein the tetracalcium phosphate is prepared from a starting mixture of one or more sources of calcium, phosphorous and oxygen which has a calcium to phosphorous ratio of less than 2; and wherein the tetracalcium phosphate is prepared and maintained under substantially anhydrous conditions prior to its contact with the aqueous medium in combination with the other sparingly soluble calcium phosphate compound.
Claim 43
Dependent Claim
26 words
The cement of claim 33, wherein the other sparingly soluble calcium phosphate is selected from the group consisting of dicalcium phosphate dihydrate and dicalcium phosphate anhydrous.
Claim 44
Dependent Claim
40 words
The cement of claim 33, wherein the cement converts in major part to hydroxyapatite having a diametral tensile strength of at least 10 MPa, and is substantially resorbable and replaced by bony tissue when implanted in contact with living bone.
Claim 45
Dependent Claim
18 words
The cement of claim 35 wherein the cement sets reliably and reproducibly in less than about 30 minutes.
Claim 46
Dependent Claim
22 words
The calcium phosphate cement of claim 33 wherein the tetracalcium phosphate to dicalcium phosphate ratio is between about 1:1 and about 1:4.
Claim 47
Dependent Claim
16 words
A biological implant comprised of the cement of claim 31 inserted into contact with living tissue.
Claim 48
Dependent Claim
16 words
A biological implant comprised of the cement of claim 33 inserted into contact with living tissue.
Claim 49
Dependent Claim
18 words
A biological implant comprised of the tissue substitute precursor of claim 27 inserted into contact with living tissue.
Claim 50
Dependent Claim
18 words
A biological implant comprised of the tissue substitute precursor of claim 28 inserted into contact with living tissue.
Claim 51
Dependent Claim
25 words
A method of bonding living tissue comprising inserting the tissue substitute precursor of claim 27 as a bridging agent between the tissues to be bonded.
Claim 52
Dependent Claim
25 words
A method of bonding living tissue comprising inserting the tissue substitute precursor of claim 28 as a bridging agent between the tissues to be bonded.
Claim 53
Dependent Claim
18 words
A method of augmenting bony tissue comprising inserting in contact with that tissue the cement of claim 31.
Claim 54
Dependent Claim
18 words
A method of augmenting bony tissue comprising inserting in contact with that tissue the cement of claim 33.
Claim 55
Dependent Claim
16 words
A method of repairing bony defects comprising filling the defect with the cement of claim 31.
Claim 56
Dependent Claim
16 words
A method of repairing bony defects comprising filling the defect with the cement of claim 33.
Claim 57
Dependent Claim
57 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 prepared from a mixture of one or more sources of calcium, phosphorus and oxygen which has a calcium to phosphorous ratio of less than 2.
Claim 58
Dependent Claim
57 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 prepared from a mixture of one or more sources of calcium, phosphorus and oxygen which has a calcium to phosphorous ratio of less than 2.
Claim 59
Dependent Claim
37 words
The method of claim 48 wherein the other sparingly soluble calcium phosphate is selected from the group consisting of monocalcium phosphate, dicalcium phosphate anhydrous, dicalcium phosphate dihydrate, alpha-tricalcium phosphate, beta-tricalcium phosphate, octacalcium phosphate, and amorphous calcium phosphate.
Claim 60
Dependent Claim
26 words
The method of claim 49, wherein the other sparingly soluble calcium phosphate is selected from the group consisting of dicalcium phosphate anhydrous and dicalcium phosphate dihydrate.
Claim 61
Dependent Claim
56 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 preparing and maintaining the tetracalcium phosphate under substantially anhydrous conditions prior to its contact with the aqueous medium in combination with the other sparingly soluble calcium phosphates.
Claim 62
Dependent Claim
56 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 preparing and maintaining the tetracalcium phosphate under substantially anhydrous conditions prior to its contact with the aqueous medium in combination with the other sparingly soluble calcium phosphates.
Claim 63
Dependent Claim
37 words
A method as in claim 51 wherein the sparingly soluble calcium phosphate is selected from the group consisting of monocalcium phosphate, dicalcium phosphate anhydrous, dicalcium phosphate dihydrate, alpha-tricalcium phosphate, beta-tricalcium phosphate, octacalcium phosphate, and amorphous calcium phosphate.
Claim 64
Dependent Claim
27 words
A method as in claim 52 wherein the other sparingly soluble calcium phosphate is selected from the group consisting of dicalcium phosphate anhydrous and dicalcium phosphate dihydrate.
Claim 65
Dependent Claim
89 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 prepared from a mixture of one or more sources of calcium, phosphorous and oxygen which has a calcium to phosphorous ratio of less than 2; and wherein the tetracalcium phosphate is prepared and maintained under substantially anhydrous conditions prior to its contact with the aqueous medium in combination with the other sparingly soluble calcium phosphate compounds.
Claim 66
Dependent Claim
89 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 prepared from a mixture of one or more sources of calcium, phosphorous and oxygen which has a calcium to phosphorous ratio of less than 2; and wherein the tetracalcium phosphate is prepared and maintained under substantially anhydrous conditions prior to its contact with the aqueous medium in combination with the other sparingly soluble calcium phosphate compounds.
Claim 67
Dependent Claim
91 words
An improved method for preparing a calcium phosphate cement which self-hardens substantially at ambient temperature comprising combining tetracalcium phosphate and at least one other sparingly soluble calcium phosphate compound wherein the improvement comprises employing tetracalcium phosphate prepared from a starting mixture of one or more sources of calcium, phosphorous and oxygen which has a calcium to phosphorous ratio of less than 2; and preparing and maintaining the tetracalcium phosphate under substantially anhydrous conditions prior to its contact with the aqueous medium in combination with the other sparingly soluble calcium phosphate compound.
Claim 68
Dependent Claim
91 words
An improved method for preparing a calcium phosphate cement which self-hardens substantially at ambient temperature comprising combining tetracalcium phosphate and at least one other sparingly soluble calcium phosphate compound wherein the improvement comprises employing tetracalcium phosphate prepared from a starting mixture of one or more sources of calcium, phosphorous and oxygen which has a calcium to phosphorous ratio of less than 2; and preparing and maintaining the tetracalcium phosphate under substantially anhydrous conditions prior to its contact with the aqueous medium in combination with the other sparingly soluble calcium phosphate compound.
Claim 69
Dependent Claim
25 words
A formulation for increasing the remineralization potential of saliva comprising a tetracalcium phosphate based calcium phosphate-containing composition prepared according to the method of claim 54.
Claim 70
Dependent Claim
12 words
A self-hardenable industrial cement prepared according to the method of claim 55.
Claim 71
Dependent Claim
60 words
A paste comprising an aqueous mixture of tetracalcium phosphate and at least one other sparingly soluble calcium phosphate which aqueous mixture hardens into a cement at an ambient temperature wherein the tetracalcium phosphate is prepared from a starting mixture of one or more sources of calcium, phosphorous and oxygen which has a calcium to phosphorous ratio of less than 2.
Claim 72
Dependent Claim
60 words
A paste comprising an aqueous mixture of tetracalcium phosphate and at least one other sparingly soluble calcium phosphate which aqueous mixture hardens into a cement at an ambient temperature wherein the tetracalcium phosphate is prepared from a starting mixture of one or more sources of calcium, phosphorous and oxygen which has a calcium to phosphorous ratio of less than 2.
Claim 73
Dependent Claim
59 words
A paste comprising an aqueous mixture of tetracalcium phosphate and at least one other sparingly soluble calcium phosphate which aqueous mixture hardens into a cement at an ambient temperature wherein the tetracalcium phosphate is prepared and maintained under substantially anhydrous conditions prior to its contact with the aqueous medium in combination with the other sparingly soluble calcium phosphate compounds.
Claim 74
Dependent Claim
59 words
A paste comprising an aqueous mixture of tetracalcium phosphate and at least one other sparingly soluble calcium phosphate which aqueous mixture hardens into a cement at an ambient temperature wherein the tetracalcium phosphate is prepared and maintained under substantially anhydrous conditions prior to its contact with the aqueous medium in combination with the other sparingly soluble calcium phosphate compounds.
Claim 75
Dependent Claim
72 words
A slurry comprising an aqueous mixture of tetracalcium phosphate and at least one other sparingly soluble calcium phosphate, both calcium phosphates being present in the slurry in excess such that hydroxyapatite is substantially continuously precipitated from the slurry at ambient temperature, wherein the tetracalcium phosphate is prepared from a starting mixture of one or more sources of calcium, phosphorous and oxygen which has a calcium to phosphorous ratio of less than 2.
Claim 76
Dependent Claim
72 words
A slurry comprising an aqueous mixture of tetracalcium phosphate and at least one other sparingly soluble calcium phosphate, both calcium phosphates being present in the slurry in excess such that hydroxyapatite is substantially continuously precipitated from the slurry at ambient temperature, wherein the tetracalcium phosphate is prepared from a starting mixture of one or more sources of calcium, phosphorous and oxygen which has a calcium to phosphorous ratio of less than 2.
Claim 77
Dependent Claim
72 words
A slurry comprising an aqueous mixture of tetracalcium phosphate and at least one other sparingly soluble calcium phosphate, both calcium phosphates being present in the slurry in excess such that hydroxyapatite is substantially continuously precipitated from the slurry at an ambient temperature, wherein the tetracalcium phosphate is prepared and maintained under substantially anhydrous conditions prior to its contact with the aqueous medium in combination with the other sparingly soluble calcium phosphate compounds.
Claim 78
Dependent Claim
72 words
A slurry comprising an aqueous mixture of tetracalcium phosphate and at least one other sparingly soluble calcium phosphate, both calcium phosphates being present in the slurry in excess such that hydroxyapatite is substantially continuously precipitated from the slurry at an ambient temperature, wherein the tetracalcium phosphate is prepared and maintained under substantially anhydrous conditions prior to its contact with the aqueous medium in combination with the other sparingly soluble calcium phosphate compounds.
Claim 79
Dependent Claim
31 words
The slurry of claim 61 further comprising up to approximately 10% by weight of additional calcium or phosphate containing compounds in an amount sufficient to alter the pH of the slurry.
References Cited (Backward Citations)
DE2008010A1
Cited
US3679360A
Cited
US3787900A
Cited
US3929971A
Cited
US3913229A
Cited
US4097935A
Cited
US4599085A
Cited
US4497075A
Cited
JPS5858041A
Cited
USRE33221E
Cited
USRE33161E
Cited
US4612053A
Cited
JPS62275007A
Cited
US4897250A
Cited
US4880610A
Cited
US5047031A
Cited
US5053212A
Cited
US5129905A
Cited
US5238491A
Cited
US5034059A
Cited
DE4016135A1
Cited
US5037639A
Cited
EP0416761A1
Cited
JPH03193615A
Cited
EP0520690A2
Cited
US5342441A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-06-04 | 1999-12-04 | 2000-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-06-04 | 2003-12-04 | 2004-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-06-04 | 2007-12-04 | 2008-06-04 | $7700.00 | Window Closed / Lapsed |