CA2204864A1 - Process for the production of spongiosa bone ceramic having low calcium oxide content - Google Patents
Process for the production of spongiosa bone ceramic having low calcium oxide contentInfo
- Publication number
- CA2204864A1 CA2204864A1 CA 2204864 CA2204864A CA2204864A1 CA 2204864 A1 CA2204864 A1 CA 2204864A1 CA 2204864 CA2204864 CA 2204864 CA 2204864 A CA2204864 A CA 2204864A CA 2204864 A1 CA2204864 A1 CA 2204864A1
- Authority
- CA
- Canada
- Prior art keywords
- bone
- calcium oxide
- ceramic
- production
- oxide content
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 210000000988 bone and bone Anatomy 0.000 title claims abstract description 46
- 239000000919 ceramic Substances 0.000 title claims abstract description 29
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 title claims abstract description 23
- 239000000292 calcium oxide Substances 0.000 title claims abstract description 23
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 title claims abstract description 23
- 238000000034 method Methods 0.000 title claims abstract description 21
- 238000004519 manufacturing process Methods 0.000 title claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 19
- 210000002805 bone matrix Anatomy 0.000 claims abstract description 10
- 238000005406 washing Methods 0.000 claims abstract description 7
- 239000000463 material Substances 0.000 abstract description 15
- 238000005245 sintering Methods 0.000 abstract description 7
- 230000033558 biomineral tissue development Effects 0.000 abstract description 5
- 229940087373 calcium oxide Drugs 0.000 description 18
- 235000012255 calcium oxide Nutrition 0.000 description 18
- 239000002253 acid Substances 0.000 description 6
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 6
- 238000011282 treatment Methods 0.000 description 6
- 229910052588 hydroxylapatite Inorganic materials 0.000 description 5
- XYJRXVWERLGGKC-UHFFFAOYSA-D pentacalcium;hydroxide;triphosphate Chemical compound [OH-].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O XYJRXVWERLGGKC-UHFFFAOYSA-D 0.000 description 5
- 238000002441 X-ray diffraction Methods 0.000 description 4
- 238000010306 acid treatment Methods 0.000 description 3
- 238000000197 pyrolysis Methods 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- 239000012298 atmosphere Substances 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000007943 implant Substances 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 238000002386 leaching Methods 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 235000010755 mineral Nutrition 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 241000283690 Bos taurus Species 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 241000543381 Cliftonia monophylla Species 0.000 description 1
- 244000228957 Ferula foetida Species 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 229910052586 apatite Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000316 bone substitute Substances 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000008239 natural water Substances 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 230000000278 osteoconductive effect Effects 0.000 description 1
- VSIIXMUUUJUKCM-UHFFFAOYSA-D pentacalcium;fluoride;triphosphate Chemical compound [F-].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O VSIIXMUUUJUKCM-UHFFFAOYSA-D 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000008237 rinsing water Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Landscapes
- Compositions Of Oxide Ceramics (AREA)
- Materials For Medical Uses (AREA)
Abstract
The invention concerns a process for producing spongiosa bone ceramics having a low calcium oxide content. Between the mineralization of the bone material and the sintering of the ceramics, a washing step is performed with demineralized water, whereby the calcium oxide portions are eliminated from the mineralized bone matrix.
Description
~ A 02204864 1997-0~-08 Proco~s for the production of ~ oBa bone ceramic having low calcium oxide content The invention relate~ to a process for producing spongiosa bone ceramic with a low calcium oxide content.
It has been known for a relatively long time that mineralized bone which has been sintered to form a ceramic is ideally suited as bone replacement material.
With bone ceramic there is naturally a very great degree of correspondence in chemical composition, structural composition and mechanical strength with natural bone. In addition, sponyiosa bone ceramic is found to be particu-larly osteoconductive. The open, interconnecting, tra-becular structure of spongiosa bone ceramic promotes the growth of new bone matrix onto and into the ceramic, 80 that in the course of incorporation there i~ intensive colonization and therefore integration of the ceramic implant. Bone ceramics produced from bones of ~n;~l origin are therefore being increasingly employed as bone replace~ent materials in osteosynthesis and in the reconstitution of bone defects caused by illness or accident.
The production of bone ceramic from ~n;m~l bone is generally carried out by first of all freeing selected bones or bone pieces mechanically from all adhering soft parts, then cutting these bones or bone pieces roughly to size by sawing, to give pieces of suitable shape and size, which are then mineralized by the removal of all other or~anic components. The mineralization process begins first of all with the bones being boiled out several times in water. Subsequent treatment can be carried out, for instance, with fat-dissolving or protein-dissolving solvents, and/or with the aid of hydrogen peroxide, as described for example in EP 0 141 004. Methods which have proved to be particu-larly simple and effective are those of pyrolyticmineralization, in which the action of heat decomposes the organic component of the bone and the resulting carbon is subsequently burnt to completion in excess CA 02204864 1997-0~-OX
oxygen. For the bone pyrolysi~, temperatures of between 500 and 1000C are common. Following the mineralization of the bone, it is sintered to give the ceramic, with temperatures of between 800 and 1400C being common. It i~ only through sintering that the material acquires the desired ultimate strength. In the course of the pro-cedures mentioned, particular care must be taken to enQure that the porous structure of the original bone i6 retained as far a~ is possible. For the conversion of spongiose bone material to spongiosa bone ceramic, a preferred option iQ to proceed in accordance with a process set out in DE 37 27 606, in which a specific temperature regime and reductive or oxidati~e character of the atmosphere enables particularly gentle pyrolysis.
It has been found that bone ceramic has a ten-dency towards uncontrolled instability if the principal pha~e, hydroxyapatite, existQ alongside notable quantities of calcium oxide, which can be detected, for instance, by X-ray analysis. This i~ the case when the content of calcium oxide is more than 5%. The ingress of water, for example in the form of atmospheric humidity in the courQe of unprotected storage or in the organism after the implant procedure, is accnmp~n;ed by successive transformation o~ calcium oxide to calcium hydroxide, which entail~ a considerable increase in ~olume.
Depending on the proportional content, this process may extend up to complete breakdown of the ceramic.-The proportion of calcium oxide in the bone ceramic is a natural parameter and may vary with the individual nature and breed of ~n;m~l. The calcium oxide is formed by the calcium carbonate which is naturally present in the bone undergoing conver6ion, in the course of pyrolysis and sintering, to calcium oxide.
DE 40 28 683 proposed treating the mineralized bone material, prior to sintering, with an aqueou ~olution of an organic acid, especially citric acid. This B tep leaches calcium oxide components out of the material, BO that the bone ceramic obtained after Qintering has, according to X-ray analysis, a hydroxy-CA 02204X64 1997-0~-08 .
apatite content of more than 99~.
Although this procedure iB highly effecti~e and leads to a useful ~table bone ceramic, it is not without disadvantage~. Thece disadvantages lie firstly in the operative area of the process regime. Thus, in the case of pyrolytic mineralization in particular, the material must first be cooled to room temperature again in order to enable the acid treatment and the necessary rin~ing operations to be carried out. After this, the material must be heated up again from scratch for sintering. These operations are time-consuming and energy-intensi~e. In addition, the preparation and consumption of the acid solution and the consumption of rinsing water for wA~;ng the material to neutrality increase the production costs.
Furthermore, the control and monitoring of the acid treatment step iB not simple. On the one hand, it must be en~ured here that virtually all of the calcium oxide is leached out, while on the other hand little or none of the hydroxyapatite matrix must be attacked by the acid.
The spongiose fine structure has at this point in the proces~ not yet undergone sufficient solidification, and i~ therefore highly sensitive. The object of the present invention wa~ therefore to lessen the abovementioned disadvantages of the prior procedure.
Surprisingly it has now been found that calcium-oxide components present in mineralized bone matrix can readily be removed if the bone matrix is subjected to a wa~hing operation with demineralized water at a tempera-ture of from lO to 80C over a period of from 4 hours to 7 day~. The leaching of calcium oxide using acid, especially aqueous citric acid ~olution, has therefore been found to be unnecessary.
The invention thus provides a process for the production of spongiosa bone ceramic with a low calcium oxide content, in which process spongiose bones cut into pieces are mineralized by the removal of all organic constituents and then the mineral bone matrix is sintered - to the ceramic, which process iB characterized in that, in order to remove calcium oxide components from the CA 02204864 1997-0~-OX
mineralized bone matrix, the latter is subjectQd to extractive washing with demineralized water at a tempera-ture of from 10 to 80C over a period of from 4 hour~ to 7 dayg The process according to the invention is carried out in practice in complete analogy to that known from DE 40 28 683. The only difference here is that the acid treatment step provided between the mineralization of the bone material and the sintering to a ceramic is replaced by a treatment with demineralized water. Demineralized water is known per se and is readily available. It can be prepared in any desired quantity by generally known methods from natural water, for example by single or multiple distillation and/or removal of the dissolved mineral salts using ion exchanges. In general, demineralized water has a slightly acid pH of about 6Ø
It is assumed that this slightly acid character of the demineralized water favours the extractive washing of calcium oxide from the mineralized bone matrix.
For the extractive washing operation it is ~ufficient to con~ey the mineralized bone material, cut into pieces, into an appropriately dimensioned bath of demineralized water and to leave it there for a time which appears to be sufficient and expedient at an appropriate temperat`ure. Circulation or agitation of the water bath may contribute to leaching out the soluble constituents. It has been found adequate and expedient to employ a ratio of 10 1 of water per kg of bone material and a duration of treatment of from 4 hours to 7 day~ at a bath temperature of between 10 and 80C. Changing the washing water one or more times, or continuous flushing with fresh demineralized water, has a beneficial efect on the result and may shorten the treatment time. The procedure indicated enables virtually all of the content of calcium oxide present or to be expected in the bone matrix to be removed, essentially without residue. In general, the natural amount of calcium oxide in the bone varies between 5 and 10%. Through X-ray analysis on the ceramic ultimately obtained, it is found that the ; CA 02204864 1997-05-08 material ha~ a hydroxyapatite content of more than 95%
and in general of 97-99%. Calcium oxide can be detected only in traces if at all.
The procesR according to the invention enables a ~aving of not inconsiderable gua tities of the acid which haR hitherto been required to achieve a comparable result. In addition, after-rinsing operations to wa~h the material to neutrality are dispen~ed with, therefore affording additional savings in cost and time. Moreover, the process according to the invention is substantially more gentle, since the hydroxyapatite matrix is not attacked by the treatment with demineraIized water.
After the end of the extractive washing operation, the pieces are dried and then sintered to ceramic in a conventional manner.
Example Raw heads of bone, freed from soft parts, from newly slaughtered cattle are sawn into rectangular piece~
with ~;~en~ions of roughly 30 x 30 x 100 mm which are boiled out with water three times for about 1 hour.
The bone pieces are then dried at 110C for 6 hours. They are then heated under a nitrogen atmosphere to 450C over the course of 9 hours. During a subsequent 20-hour heating period from 450C to 600C, the atmos-phere is changed over in linear progression to atmos-pheric oxygen, and heating is continued to 900C over the course of 5 hours. After cooling, the pieces are placed into a bath of demineralized water (10 l per kg of bone material) and treated in the agitated bath at a tempera-ture of 20C for a period of 48 hours. After this treat-ment, the pieces are rinsed three times with demineralized water.
For final sintering, the pieces are heated to 1250C over the course of 21 hours, held at this tempera-ture for 3 hours, and then allowed to cool down.
The resulting bone ceramic pieces exhibit theunchanged porou~ Rtructure of the original spongio~e ; CA 02204864 1997-05-08 bone. According to X-ray analysi~ the ceramic has a hydroxyapatite content of about 99~.
It has been known for a relatively long time that mineralized bone which has been sintered to form a ceramic is ideally suited as bone replacement material.
With bone ceramic there is naturally a very great degree of correspondence in chemical composition, structural composition and mechanical strength with natural bone. In addition, sponyiosa bone ceramic is found to be particu-larly osteoconductive. The open, interconnecting, tra-becular structure of spongiosa bone ceramic promotes the growth of new bone matrix onto and into the ceramic, 80 that in the course of incorporation there i~ intensive colonization and therefore integration of the ceramic implant. Bone ceramics produced from bones of ~n;~l origin are therefore being increasingly employed as bone replace~ent materials in osteosynthesis and in the reconstitution of bone defects caused by illness or accident.
The production of bone ceramic from ~n;m~l bone is generally carried out by first of all freeing selected bones or bone pieces mechanically from all adhering soft parts, then cutting these bones or bone pieces roughly to size by sawing, to give pieces of suitable shape and size, which are then mineralized by the removal of all other or~anic components. The mineralization process begins first of all with the bones being boiled out several times in water. Subsequent treatment can be carried out, for instance, with fat-dissolving or protein-dissolving solvents, and/or with the aid of hydrogen peroxide, as described for example in EP 0 141 004. Methods which have proved to be particu-larly simple and effective are those of pyrolyticmineralization, in which the action of heat decomposes the organic component of the bone and the resulting carbon is subsequently burnt to completion in excess CA 02204864 1997-0~-OX
oxygen. For the bone pyrolysi~, temperatures of between 500 and 1000C are common. Following the mineralization of the bone, it is sintered to give the ceramic, with temperatures of between 800 and 1400C being common. It i~ only through sintering that the material acquires the desired ultimate strength. In the course of the pro-cedures mentioned, particular care must be taken to enQure that the porous structure of the original bone i6 retained as far a~ is possible. For the conversion of spongiose bone material to spongiosa bone ceramic, a preferred option iQ to proceed in accordance with a process set out in DE 37 27 606, in which a specific temperature regime and reductive or oxidati~e character of the atmosphere enables particularly gentle pyrolysis.
It has been found that bone ceramic has a ten-dency towards uncontrolled instability if the principal pha~e, hydroxyapatite, existQ alongside notable quantities of calcium oxide, which can be detected, for instance, by X-ray analysis. This i~ the case when the content of calcium oxide is more than 5%. The ingress of water, for example in the form of atmospheric humidity in the courQe of unprotected storage or in the organism after the implant procedure, is accnmp~n;ed by successive transformation o~ calcium oxide to calcium hydroxide, which entail~ a considerable increase in ~olume.
Depending on the proportional content, this process may extend up to complete breakdown of the ceramic.-The proportion of calcium oxide in the bone ceramic is a natural parameter and may vary with the individual nature and breed of ~n;m~l. The calcium oxide is formed by the calcium carbonate which is naturally present in the bone undergoing conver6ion, in the course of pyrolysis and sintering, to calcium oxide.
DE 40 28 683 proposed treating the mineralized bone material, prior to sintering, with an aqueou ~olution of an organic acid, especially citric acid. This B tep leaches calcium oxide components out of the material, BO that the bone ceramic obtained after Qintering has, according to X-ray analysis, a hydroxy-CA 02204X64 1997-0~-08 .
apatite content of more than 99~.
Although this procedure iB highly effecti~e and leads to a useful ~table bone ceramic, it is not without disadvantage~. Thece disadvantages lie firstly in the operative area of the process regime. Thus, in the case of pyrolytic mineralization in particular, the material must first be cooled to room temperature again in order to enable the acid treatment and the necessary rin~ing operations to be carried out. After this, the material must be heated up again from scratch for sintering. These operations are time-consuming and energy-intensi~e. In addition, the preparation and consumption of the acid solution and the consumption of rinsing water for wA~;ng the material to neutrality increase the production costs.
Furthermore, the control and monitoring of the acid treatment step iB not simple. On the one hand, it must be en~ured here that virtually all of the calcium oxide is leached out, while on the other hand little or none of the hydroxyapatite matrix must be attacked by the acid.
The spongiose fine structure has at this point in the proces~ not yet undergone sufficient solidification, and i~ therefore highly sensitive. The object of the present invention wa~ therefore to lessen the abovementioned disadvantages of the prior procedure.
Surprisingly it has now been found that calcium-oxide components present in mineralized bone matrix can readily be removed if the bone matrix is subjected to a wa~hing operation with demineralized water at a tempera-ture of from lO to 80C over a period of from 4 hours to 7 day~. The leaching of calcium oxide using acid, especially aqueous citric acid ~olution, has therefore been found to be unnecessary.
The invention thus provides a process for the production of spongiosa bone ceramic with a low calcium oxide content, in which process spongiose bones cut into pieces are mineralized by the removal of all organic constituents and then the mineral bone matrix is sintered - to the ceramic, which process iB characterized in that, in order to remove calcium oxide components from the CA 02204864 1997-0~-OX
mineralized bone matrix, the latter is subjectQd to extractive washing with demineralized water at a tempera-ture of from 10 to 80C over a period of from 4 hour~ to 7 dayg The process according to the invention is carried out in practice in complete analogy to that known from DE 40 28 683. The only difference here is that the acid treatment step provided between the mineralization of the bone material and the sintering to a ceramic is replaced by a treatment with demineralized water. Demineralized water is known per se and is readily available. It can be prepared in any desired quantity by generally known methods from natural water, for example by single or multiple distillation and/or removal of the dissolved mineral salts using ion exchanges. In general, demineralized water has a slightly acid pH of about 6Ø
It is assumed that this slightly acid character of the demineralized water favours the extractive washing of calcium oxide from the mineralized bone matrix.
For the extractive washing operation it is ~ufficient to con~ey the mineralized bone material, cut into pieces, into an appropriately dimensioned bath of demineralized water and to leave it there for a time which appears to be sufficient and expedient at an appropriate temperat`ure. Circulation or agitation of the water bath may contribute to leaching out the soluble constituents. It has been found adequate and expedient to employ a ratio of 10 1 of water per kg of bone material and a duration of treatment of from 4 hours to 7 day~ at a bath temperature of between 10 and 80C. Changing the washing water one or more times, or continuous flushing with fresh demineralized water, has a beneficial efect on the result and may shorten the treatment time. The procedure indicated enables virtually all of the content of calcium oxide present or to be expected in the bone matrix to be removed, essentially without residue. In general, the natural amount of calcium oxide in the bone varies between 5 and 10%. Through X-ray analysis on the ceramic ultimately obtained, it is found that the ; CA 02204864 1997-05-08 material ha~ a hydroxyapatite content of more than 95%
and in general of 97-99%. Calcium oxide can be detected only in traces if at all.
The procesR according to the invention enables a ~aving of not inconsiderable gua tities of the acid which haR hitherto been required to achieve a comparable result. In addition, after-rinsing operations to wa~h the material to neutrality are dispen~ed with, therefore affording additional savings in cost and time. Moreover, the process according to the invention is substantially more gentle, since the hydroxyapatite matrix is not attacked by the treatment with demineraIized water.
After the end of the extractive washing operation, the pieces are dried and then sintered to ceramic in a conventional manner.
Example Raw heads of bone, freed from soft parts, from newly slaughtered cattle are sawn into rectangular piece~
with ~;~en~ions of roughly 30 x 30 x 100 mm which are boiled out with water three times for about 1 hour.
The bone pieces are then dried at 110C for 6 hours. They are then heated under a nitrogen atmosphere to 450C over the course of 9 hours. During a subsequent 20-hour heating period from 450C to 600C, the atmos-phere is changed over in linear progression to atmos-pheric oxygen, and heating is continued to 900C over the course of 5 hours. After cooling, the pieces are placed into a bath of demineralized water (10 l per kg of bone material) and treated in the agitated bath at a tempera-ture of 20C for a period of 48 hours. After this treat-ment, the pieces are rinsed three times with demineralized water.
For final sintering, the pieces are heated to 1250C over the course of 21 hours, held at this tempera-ture for 3 hours, and then allowed to cool down.
The resulting bone ceramic pieces exhibit theunchanged porou~ Rtructure of the original spongio~e ; CA 02204864 1997-05-08 bone. According to X-ray analysi~ the ceramic has a hydroxyapatite content of about 99~.
Claims
claim Process for the production of spongiosa bone ceramic with a low calcium oxide content, in which process spongiose bones cut into pieces are mineralized by the removal of all organic components and then the mineralized bone matrix is sintered to a ceramic, characterized in that, in order to remove calcium oxide components from the mineralized bone matrix, the latter is subjected to extractive washing with demineralized water at temperatures of from 10 to 80°C over a period of from 4 hours to 7 days.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4440149.3 | 1994-11-10 | ||
| DE4440149A DE4440149A1 (en) | 1994-11-10 | 1994-11-10 | Process for the production of spongiosa bone ceramics low in calcium oxide |
| PCT/EP1995/004285 WO1996014886A1 (en) | 1994-11-10 | 1995-11-02 | Process for producing spongiosa bone ceramics having a low calcium oxide content |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2204864A1 true CA2204864A1 (en) | 1996-05-23 |
Family
ID=29403404
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2204864 Abandoned CA2204864A1 (en) | 1994-11-10 | 1995-11-02 | Process for the production of spongiosa bone ceramic having low calcium oxide content |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2204864A1 (en) |
-
1995
- 1995-11-02 CA CA 2204864 patent/CA2204864A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |