Inorganic resorbable bone substitute material
Abstract
The invention relates in particular to a hydroxyl apatite/silica granular material of defined morphology, a highly porous bone substitute material based on this granular material and a glass ceramic material based in turn thereon as bone substitute material which is characterized by a variable mechanical strength, and shaped bodies of this material, materials of different mechanical strength being preferably used in the shaped body. The bone substitute materials according to the invention are characterized by a high resorbability in vivo.
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61 claims: 16 independent, 45 dependent
- 1Patent claims Zastrzeżenia patentowe 1. Calcium phosphate based granulate, characterized in that the crystalline calcium phosphate is embedded in a silica xerogel matrix, which material is obtained by obtaining calcium phosphate in a precipitation reaction, the solution with the precipitated calcium phosphate being homogenized by stirring, a silicic acid solution is added high concentration wherein the mixture sets due to the onset of gel formation and the mixture moves into the xerogel matrix as a result of solvent removal, the calcium phosphate crystallites lying in the xerogel matrix having a size from about 10 nm to about 2000 nm and the granule grains having a size of 1 ąm up to 1000 am, and the silica fraction is in the range from 2 to 80% by weight, preferably in the range from 4 to 50% by weight based on the total weight of the granulate grains. 1. Granulat oparty na fosforanie wapnia, znamienny tym, że krystaliczny fosforan wapnia jest osadzony w krzemionkowej matrycy kserożelowej, który to materiał uzyskuje się przez otrzymywanie fosforanu wapnia w reakcji wytrącania, przy czym roztwór z wytrąconym fosforanem wapnia homogenizuje się przez mieszanie, dodaje się roztwór kwasu krzemowego o dużym stężeniu, przy czym mieszanina ulega związaniu w następstwie rozpoczynającego się tworzenia żelu i mieszaninę przemieszcza się do matrycy kserożelowej w wyniku usunięcia rozpuszczalnika, przy czym krystality fosforanu wapnia leżące w matrycy kserożelowej mają wielkość od około 10 nm do około 2000 nm i ziarna granulatu mają wielkość od 1 ąm do 1000 ąm, a udział krzemionki mieści się w zakresie od 2 do 80% wagowo, korzystnie w zakresie od 4 do 50% wagowo w odniesieniu do całkowitej masy ziaren granulatu.
- 11A high porous bone replacement material, characterized in that it comprises granule grains as defined in claim 1. 1 to 10, which creates a three-dimensional structure that, in addition to the pores present in the granulate grains, has pores of a size similar to the granule grain size. 11. Wysokoporowaty materiał zastępujący kość, znamienny tym, że obejmuje on ziarna granulatu jak określono w zastrz. 1 do 10, który tworzy trójwymiarową strukturę, która poza porami obecnymi w ziarnach granulatu, wykazuje pory o wielkości zbliżonej do wielkości ziaren granulatu.
- 18A bone replacement material, characterized in that it comprises a glass matrix in which crystalline calcium phosphate is embedded, which material is obtained by obtaining calcium phosphate in a precipitation reaction, whereby the solution with the precipitated calcium phosphate is homogenized by stirring, an acid solution is added high concentration silicon wherein the mixture sets due to the onset of gel formation and the mixture moves to the xerogel matrix as a result of removal of the solvent and then the xerogel matrix is transformed into a glassy state using a network modifier, with crystallites ranging from 10 nm to 2000 nm silicas is in the range of 2 to 80% by weight, preferably in the range of 4 to 50% by weight based on the total weight of the bone replacement material. 18. Materiał zastępujący kość, znamienny tym, że zawiera on matrycę szklaną, w której osadzony jest krystaliczny fosforan wapnia, który to materiał uzyskuje się przez otrzymywanie fosforanu wapnia w reakcji wytrącania, przy czym roztwór z wytrąconym fosforanem wapnia homogenizuje się przez mieszanie, dodaje się roztwór kwasu krzemowego o dużym stężeniu, przy czym mieszanina ulega związaniu w następstwie rozpoczynającego się tworzenia żelu i mieszaninę przemieszcza się do matrycy kserożelowej w wyniku usunięcia rozpuszczalnika i następnie matrycę kserożelową przekształca się w stan szklisty za pomocą modyfikatora sieci, przy czym krystality mają wielkość od 10 nm do 2000 nm, a udział krzemionki mieści się w zakresie od 2 do 80% wagowo, korzystnie w zakresie od 4 do 50% wagowo w odniesieniu do całkowitej masy materiału zastępującego kość.
- 22Bone replacement material according to claim The process of any one of claims 18 to 21, characterized in that it is obtained from bone replacement material as defined in claim 1. 11 to 17, wherein the silica xerogel matrix is partially or completely transformed into a glassy state, the proportion of the glassy phase in the matrix is in the range from 0 to 100% by volume, preferably from 10 to 80% by volume, in particular from 60% by volume to 80 % by volume. 22. Materiał zastępujący kość według zastrz. 18 do 21, znamienny tym, że uzyskuje się go z materiału zastępującego kość jak określono w zastrz. 11 do 17, w którym krzemionkową matrycę kserożelową przekształca się częściowo lub całkowicie w stan szklisty, udział fazy szklistej w matrycy mieści się w zakresie od 0 do 100% objętościowo, korzystnie od 10 do 80% objętościowo, a zwłaszcza od 60% objętościowo do 80% objętościowo.
- 27A shaped body from bone replacement material as defined in claim 11. A method as claimed in any one of claims 11 to 17, characterized in that it comprises on at least one side a layer of bone replacement material as defined in claim 1. 18 to 24, holes present in this layer with a diameter of 0.5 to 5 mm, whose volume proportion is from 5 to 80%, relative to the total volume of the layer, and these holes in turn are filled with granules as defined in claim 1 to 10 and / or bone replacement material as defined in claim 1. 11 until 17. 27. Kształtka z materiału zastępującego kość jak określono w zastrz. 11 do 17, znamienna tym, że zawiera ona na co najmniej jednej stronie warstwę materiału zastępującego kość jak określono w zastrz. 18 do 24, otwory obecne w tej warstwie o średnicy od 0,5 do 5 mm, których udział objętościowy wynosi od 5 do 80%, w odniesieniu do całkowitej objętości warstwy i te otwory z kolei wypełnione są granulatem jak określono w zastrz. 1 do 10 i/lub materiałem zastępującym kość jak określono w zastrz. 11 do 17.
- 32The use of granules as defined in claim 1 to 10, for the manufacture of a medicament or medicinal product for osteoporotic bone reconstruction, to stimulate bone reconstruction in the transient range for loose metal implants, or to stimulate the treatment of paradontic defects. 32. Zastosowanie granulatu jak określono w zastrz. 1 do 10, do wytwarzania leku lub produktu leczniczego dla odbudowy osteoporotycznych kości, do stymulowania odbudowy kości w zakresie przejściowym do luźnych metalowych implantów lub do stymulowania wyleczenia defektów paradontalnych.
- 34A medicament or medicinal product, characterized in that it comprises granules as defined in claim 1. 1 to 10, which mixes with the patient's bone marrow or blood. 34. Lek lub produkt leczniczy, znamienny tym, że obejmuje on granulat jak określono w zastrz. 1 do 10, który miesza się ze szpikiem kostnym lub krwią pacjenta.
- 35The method of producing granules as defined in claim 1 to 10, characterized in that the hydroxylapatite precipitates in an aqueous solution, wherein the apatite has a Ca / P ratio of 1.50 to 1.67 due to a fixed concentration of ions in the solution, pH, homogeneity of the mixture of starting products and the temperature determined by known methods in such a way that crystallites with a size of 10 nm to 2000 nm and granules with a size of 1 μη to 1000 pm are formed, the precipitated hydroxylapatite is homogeneously deposited in a silica hydrogel without agglomerates formed in an aqueous solution, by supplying silicic acid, preferably orthosilicic acid, to the aqueous solution and adjusting the pH in the range from 2 to 8, preferably from 5 to 6.5, so that gel, the amount of silicic acid used is selected in such a way that the silica content is in the range from 2 to 80% by weight, preferably in the range from 4 to 50% by weight, based on the total mass of granulate grains formed and the resulting hydrogel is subjected to granulation followed by a drying process to form xerogel as a result of which calcium phosphate crystallites are present in the xerogel matrix. 35. Sposób wytwarzania granulatu jak określono w zastrz. 1 do 10, znamienny tym, że hydroksyloapatyt wytrąca się w roztworze wodnym, przy czym apatyt wykazuje, wskutek ustalonego stężenia jonów w roztworze, stosunek Ca/P od 1,50 do 1,67, pH, jednorodność mieszaniny wyjściowych produktów i temperaturę ustaloną za pomocą znanych sposobów w taki sposób, że powstają krystality o wielkości 10 nm do 2000 nm i ziarna granulatu o wielkości od 1 μη do 1000 pm, wytrącony hydroksyloapatyt w sposób jednorodny jest osadzony w hydrożelu krzemionkowym bez aglomeratów powstających w roztworze wodnym, przez dostarczenie kwasu krzemowego, korzystnie kwasu ortokrzemowego, do wodnego roztworu i ustalenie pH w zakresie od 2 do 8, korzystnie od 5 do 6,5 tak, że powstaje żel, ilość użytego kwasu krzemowego dobiera się w taki sposób, że udział krzemionki mieści się w zakresie od 2 do 80% wagowo, korzystnie w zakresie od 4 do 50% wagowo, w odniesieniu do całkowitej masy utworzonych ziaren granulatu i powstały hydrożel poddaje się granulacji i następnie procesowi suszenia dla utworzenia kserożelu w wyniku czego krystality fosforanu wapnia są obecne w matrycy kserożelu.
- 38The method of producing granules as defined in claim 1 to 10, characterized in that the hydroxylapatite precipitates in an aqueous solution, wherein the apatite has a Ca / P ratio of 1.50 to 1.67 due to a fixed concentration of ions in the solution, pH, homogeneity of the mixture of starting products and the temperature determined by known methods in such a way that crystallites with a size of about 10 nm to about 2000 nm and granules with a size of about 1 μη to about 1000 pm are formed, the precipitated hydroxylapatite is homogeneously deposited in a silica hydrogel without agglomerates formed in an aqueous solution, by supplying silicic acid, preferably orthosilicic acid, to the aqueous solution and adjusting the pH in the range from 2 to 8, preferably from 5 to 6.5, so that gel, the amount of silicic acid used is selected in such a way that the silica content is in the range from 2 to 80% by weight, preferably in the range from 4 to 50% by weight, based on the total weight of the granulate grains formed, spray drying is carried out prior to gel formation. 38. Sposób wytwarzania granulatu jak określono w zastrz. 1 do 10, znamienny tym, że hydroksyloapatyt wytrąca się w roztworze wodnym, przy czym apatyt wykazuje, wskutek ustalonego stężenia jonów w roztworze, stosunek Ca/P od 1,50 do 1,67, pH, jednorodność mieszaniny wyjściowych produktów i temperaturę ustaloną za pomocą znanych sposobów w taki sposób, że powstają krystality o wielkości około 10 nm do około 2000 nm i ziarna granulatu o wielkości od około 1 μη do około 1000 pm, wytrącony hydroksyloapatyt w sposób jednorodny jest osadzony w hydrożelu krzemionkowym bez aglomeratów powstających w roztworze wodnym, przez dostarczenie kwasu krzemowego, korzystnie kwasu ortokrzemowego, do wodnego roztworu i ustalenie pH w zakresie od 2 do 8, korzystnie od 5 do 6,5 tak, że powstaje żel, ilość użytego kwasu krzemowego dobiera się w taki sposób, że udział krzemionki mieści się w zakresie od 2 do 80% wagowo, korzystnie w zakresie od 4 do 50% wagowo, w odniesieniu do całkowitej masy utworzonych ziaren granulatu, przeprowadza się suszenie rozpyłowe przed utworzeniem żelu.
- 39The method of producing granules as defined in claim 1 to 10, characterized in that hydroxylapatite precipitates in an aqueous solution, with apatite exhibiting;as a result of a fixed concentration of ions in the solution;a ratio of Ca / P from 1.50 to 1.67, pH, homogeneity of the mixture of starting products and a fixed temperature by known methods in such a way that crystallites with a size of 10 nm to 2000 nm and granulate grains with a size of 1 μη to 1000 μπι are formed, the precipitated hydroxylapatite is homogeneously deposited in a silica hydrogel without agglomerates formed in an aqueous solution, by supplying silicic acid, preferably orthosilicic acid, to the aqueous solution and adjusting the pH in the range from 2 to 8, preferably from 5 to 6.5, so that gel, the amount of silicic acid used is selected in such a way that the silica content is in the range from 2 to 80% by weight, preferably in the range from 4 to 50% by weight, based on the total weight of the granulate grains formed and the resulting hydrogel is cooled to below the freezing point of the solvent and the silica / hydroxylapatite granulate is filtered off after thawing. 39. Sposób wytwarzania granulatu jak określono w zastrz. 1 do 10, znamienny tym, że hydroksyloapatyt wytrąca się w roztworze wodnym, przy czym apatyt wykazuje;, wskutek ustalonego stężenia jonów w roztworze;, stosunek Ca/P od 1,50 do 1,67, pH, jednorodność mieszaniny wyjściowych produktów i temperaturę ustaloną za pomocą znanych sposobów w taki sposób, że powstają krystality o wielkości 10 nm do 2000 nm i ziarna granulatu o wielkości od 1 μη do 1000 μπι, wytrącony hydroksyloapatyt w sposób jednorodny jest osadzony w hydrożelu krzemionkowym bez aglomeratów powstających w roztworze wodnym, przez dostarczenie kwasu krzemowego, korzystnie kwasu ortokrzemowego, do wodnego roztworu i ustalenie pH w zakresie od 2 do 8, korzystnie od 5 do 6,5 tak, że powstaje żel, ilość użytego kwasu krzemowego dobiera się w taki sposób, że udział krzemionki mieści się w zakresie od 2 do 80% wagowo, korzystnie w zakresie od 4 do 50% wagowo, w odniesieniu do całkowitej masy utworzonych ziaren granulatu i powstały hydrożel ochładza się do temperatury poniżej temperatury zamarzania rozpuszczalnika i granulat krzemionka/ hydroksyloapatyt odsącza się po rozmrożeniu.
- 45A method of producing bone replacement material as defined in claim A process as claimed in any one of claims 1 to 17, characterized in that a method as defined in claim 1 is carried out initially. 35 to 44 and the resulting granulate is mixed with water to form a thick, preferably about 100 to 300 ml of water is added to 100 g of granulate, then the pH is adjusted preferably in the range of from about 2 to about 8, particularly preferably from about 5 to 6.5 , the layer is poured into any desired form and dried, drying preferably takes place at a temperature from room temperature to 200ABOUTC, particularly preferably at a temperature between 80ABOUTC and 130ABOUTC. 45. Sposób wytwarzania materiału zastępującego kości jak określono w zastrz. 1 do 17, znamienny tym, że początkowo prowadzi się sposób jak określono w zastrz. 35 do 44 i uzyskany granulat miesza się z wodą do wytworzenia gęstwy, korzystnie około 100 do 300 ml wody dodaje się do 100 g granulatu, następnie ustala się pH korzystnie w zakresie od około 2 do około 8, szczególnie korzystnie od około 5 do 6,5, gęstwę wylewa się do dowolnej żądanej formy i suszy się, suszenie korzystnie przebiega w temperaturze od temperatury pokojowej do 200OC, szczególnie korzystnie w temperaturze pomiędzy 80OC i 130OC.
- 58The use of a high porous bone replacement material as defined in claim 11 to 17 for the manufacture of a medicament or medicinal product for filling small bone defects. 58. Zastosowanie wysokoporowatego materiału zastępującego kości jak określono w zastrz. 11 do 17 dla wytwarzania leku lub produktu leczniczego dla wypełniania małych defektów kości.
- 61A medicament or medicinal product which contains a high porous bone replacement material as defined in claim 1. 11 to 17 or bone replacement material as defined in claim 18 to 26, the pores of which are filled with bone marrow or blood of the patient being treated. 61. Lek lub produkt leczniczy, znamienny tym, że zawiera on wysokoporowaty materiał zastępujący kość jak określono w zastrz. 11 do 17 lub materiał zastępujący kość jak określono w zastrz. 18 do 26, którego pory są wypełnione szpikiem kostnym lub krwią leczonego pacjenta. Artoss GmbH Pełnomocnik:Artoss GmbH Representative: FIG. 1 FIG. 1 FIG. 2 FIG. 2 FIG. 3 FIG. 3 FIG. 4 FIG. 4 FIG. 5 FIG. 5 Granule grain size (nm) Wielkość ziarna granulatu (nm) FIG. 6 FIG. 6 FIG. 7 FIG. 7 FIG. 8 FIG. 8 FIG. 9 FIG. 9 FIG. 10 FIG. 10 FIG. 11 FIG. 11 FIG. 12 FIG. 12 FIG. 13 FIG. 13 FIG. 14 FIG. 14 FIG. 15 FIG. 15 FIG 16 FIG 16 FIG. 17 FIG. 17 FIG. 18 FIG. 18
Independent claims16
154 paragraphs, as filed
The subject of the invention is therefore granules and a group of bone replacement materials based thereon which are described below. The granulate is based on calcium phosphate, in which crystalline calcium phosphate is embedded in a silica xerogel matrix, the crystallites having an average diameter from 10 nm to 2000 nm, preferably from 10 nm to 200 nm, and particularly preferred shallow crystallites have a thickness of from 2, 5 nmm to 10 nm and average diameter from 10 nm to 200 nm. The granulate grains have an average diameter of from about 1 to about 1000, and the silica fraction is in the range of from about 2 to about 80% by weight, preferably in the range of from about 4 to about 50% by weight
The pores of the xerogel have an average diameter of 0.5 nm to 20 nm. In granulate grains they constitute from 10% by volume to about 60% by volume with respect to the volume of granulate grains.
Preferably, the calcium phosphate is hydroxylapatite.
The granulate in a particular embodiment may further comprise soluble calcium phosphate, wherein the soluble calcium phosphate preferably has a proportion of from about 5% by weight to 50% by weight based on the calcium phosphate content. Soluble calcium phosphate is in particular β-tricalcium phosphate (βTCP). The xerogel granulate may further comprise one or more oxides - network modifiers. The oxide network modifier (oxides - network modifiers) preferably has (has) a proportion from 0.5 to 35 mole%, preferably a proportion from 17 mole%. up to 30 mole% in relation to silica. Oxide - the network modifier is in particular Na<sub>2</sub>ABOUT.
In Fig. 1, a granular particle according to the invention is schematically illustrated. Crystals (shown in black) in granules are held together by a SiO2 xerogel (shown in gray). There is a SiO2 xerogel on the surface of the granulate particles. It should be briefly mentioned that granules from a preferred size range with a diameter of e.g. 1 pm in order of size contain 104 crystallites, when they are e.g.
plates with a diameter of 100 nm and a thickness of 1 nm and a xerogel matrix makes up 40% by weight of the granulate grain.
Building on the described hydroxylapatite / silica granulate, a highly porous bone replacement material and glass ceramics are obtained as bone replacement material with variable mechanical strength.
The starting point is a high-porous bone replacement material, which is characterized in that the granulate grains are bound together by a xerogel matrix and by packing the granule grains pores are formed that have an order of magnitude of the granule grains.
Accordingly, the high porous bone replacement material has two categories of pores. In addition to the pores just described, which are formed by packing the granules and thus in the micrometer range, there are also pores that are inside the granules and described above. These are pores in the xerogel that have an average diameter in the range from 0.5 nm to 20 nm.
In the high porous bone replacement material, the porosity is preferably from 30% by volume to 80% by volume
Fig. 2 schematically shows the structure of the high porous bone replacement material. The significant difference from the prior art bone replacement material is that the interior of the granulate particles (i.e. crystallites) is held together by SiO2. The structure can be described in such a way that each individual crystallite lies in one xerogel matrix. The product can be obtained in part by prior ceramic manufacturing processes using the described granulates, as described in detail below.
The invention further relates to a high porous bone replacement material that comprises granules of the aforementioned granules forming a three-dimensional structure which, in addition to the pores available in the granules, further comprises pores about the size of granulate. The pore diameter is in the range of 1 μη to 1000 μη, preferably in the range of 1 μη to 50 μπι.
Small parts (e.g. shaped parts, particles, lumps) of this high porous bone replacement material, preferably in the form of cylinders with an average diameter of about 0.4 to about 2 mm and a length of 1 to 6 mni, are used to fill small bone defects, preferably up to 10 cm<sup>3</sup>, especially when defects are limited to two sides of healthy bone.
The invention further relates to high porous bone replacement material, which is characterized in that in addition (i.e. in addition to the pores inside individual granule grains and in addition to the pores that are formed by (three-dimensional) packing of granulate grains) has interconnecting macropores in the range from about 100 μιπ to many thousands μη, which have a volume fraction from 10% by volume to 60% by volume High-porous replacement material the bone preferably has a total porosity of 30% by volume to 90% by volume, particularly preferably a total porosity of 60% by volume to 80% by volume
The destructive stress of high porous bone replacement material without the macropores described is from <sup>2 mp</sup>and <sup>d</sup>about <sup>15 M</sup>Pa<sup>, k</sup>orz<sup>s</sup>s<sup>t</sup>n<sup>and</sup>e <sup>3 d</sup>about <sup>10 mp</sup>and. <sup>IN</sup>s<sup>k</sup>at<sup>t</sup>e<sup>k </sup>macropores the destructive stress of the material decreases and reaches only values from 0.1 MPa to 4 MPa.
According to a particular embodiment, the high porous bone replacement material further includes one or more oxides - network modifiers. The oxide network modifier (oxides - network modifiers) preferably has (has) a proportion of 0.5 to 35 mole%, especially a proportion of 17 to 30 mole%. in relation to silica. Na2O is particularly preferred.
The invention further relates to glass ceramics as bone replacement material (or to put it otherwise)
- bone replacement material including a glass matrix) which is characterized in that the crystalline calcium phosphate is embedded in the glass matrix, the crystallites having a size from 10 nm to 2000 nm, and the glass content in the range from 4 to 80% by weight (in based on the total weight of the material), preferably in the range from 2 to 50% by weight, and the glass contains silica as the cross-linking agent. Also as a high porous bone replacement material, the bone replacement material may further contain one or more oxides - network modifiers. To avoid repetition of oxides - modifiers of the network, the following arguments are fully referred to, which equally apply to the bone replacement material described here.
The glass ceramics according to the invention as bone replacement material can be obtained from the above-mentioned high-porous bone replacement material by converting a silica xerogel matrix with a network modifier, preferably sodium oxide, into a glass state.
Using this transformation process, a fully bonded glass network is obtained from the nanoporous xerogel, which at a destructive stress of about 300 MPa to about 400 MPa increases the mechanical durability of the bone replacement material. The breaking stress of the bone replacement material described depends on the residual porosity described below, so that no theoretical values are obtained.
The invention further relates to a bone replacement material in which the glass matrix is sodium silicate. It preferably has a mechanical strength in the range of 30<sup>MP</sup>and <sup>d</sup>about <sup>200 mp</sup>and<sup>,</sup> especially Fr.<sup>d 50 MP</sup>and <sup>d</sup>about <sup>120 mp</sup>and<sup>, </sup>residual porosity from 5 to 35%, while the pores have a diameter in the range of 1 to 200.
Fig. 3 schematically shows the structure of glass ceramics. The calcium phosphate crystallites drawn in black have the same structure as in the high porous bone replacement material, but are now in the gray matrix. Residual porosity is not shown in the schematic drawing.
The process of transforming the gel into glass is associated with sintering of high porous bone replacement material. The nanoporosity is fully removed, and the described porosity in the micrometer range is reduced, so that a residual porosity of 2 to 35% by volume remains. Due to the described proportion of calcium phosphates in the glass matrix, the material is biocompatible. However, the resorption process has changed completely because there is no nanoporosity left.
Since the glass matrix is preferably a glass of sodium silicate, when using glass ceramics as a bone replacement material, sodium ions slowly go into solution and the glass transforms again into a gel-like structure with nanopores. Residual porosity in the micrometer range further enhances this effect. As a result of this process, resorption of this bone replacement material is ultimately possible.
While the process of transition of the xerogel matrix of the described high porous bone replacement material into the glass matrix is only partial, a bone replacement material can be obtained, which in terms of mechanical properties and resorption properties can be continuously set between two extremes, the high porous bone replacement material and glass ceramics as the material bone replacement.
The invention relates (accordingly) to a bone replacement material which is characterized in that the crystalline calcium phosphate is embedded in the matrix, the crystallites having a size from about 10 nm to about 2000 nm, the matrix consists of xerogel and glass, the proportion of glass in the matrix it is between 0 and 100% by volume, preferably 10% by volume to 80% by volume and particularly preferably between 60% by volume and 80% by volume, xerogel and glass consist of silica and a network modifier, preferably with a proportion of 0.5 to 35 mol%, especially with a proportion of 17 mol%. up to 30 mole% with respect to silica, the network modifier is preferably sodium oxide and the matrix is from 20 to 80% by weight, preferably from 4 to 50% by weight of bone replacement material.
Partial transition of xerogel to glass can be done by heat treatment. Because the glass transition temperature of sodium silicate glass, depending on the sodium content, ranges from about 460<sup>ABOUT</sup>C to about 800<sup>ABOUT</sup>C, it is clear that heat treatment in this temperature range very quickly leads to glass. If the temperature treatment is carried out about 20% to about 5% below the glass transition temperature established for a given composition, the process slows down, requires many hours and can be interrupted at any time point.
The second possibility of converting only partially xerogel into glass involves the use of two described granules: calcium phosphate / silica differing in the proportion of network modifier. Granules without a network modifier (Na2O) and granules with about 20 mole% Na2O based on xerogel are preferred. Highly porous bone replacement material is produced from these granules according to the method described below. If then heat treatment is carried out at about 520<sup>ABOUT</sup>C areas with Na2O turn into a glassy state, and areas without Na2O remain in the xerogel state, because temperatures of around 1000 are required<sup>ABOUT</sup>C.
The bone replacement material according to one particular embodiment is a shaped body, in particular a cube, plate, hollow cylinder or wedge.
The invention therefore also relates to a shaped body of the high porosity bone replacement material described which comprises on at least one side a layer of said bone replacement material with higher mechanical strength, preferably the described glass ceramics, wherein this layer comprises holes with a diameter of 0.5 to 5 mm representing a volume proportion of 5 to 80% relative to the total volume of the layer, and these holes are filled with the aforementioned granulate and / or the aforementioned high porous bone replacement material.
For the method of producing the currently described materials, which are still the subject of the invention, the starting point is the production of calcium phosphate granules, which is characterized in that the crystallites, as described, lie in a xerogel matrix. Starting from this granulate, a high porous bone replacement material is produced, which again is a prerequisite for the production of glass ceramics as bone replacement material.
According to the invention, in the production of silica-containing granules, the production of calcium phosphate by a precipitation reaction in which the so-called thickening is related to the silica gel formation process. Only in this way can it be achieved that separate nanocrystals can be built into the xerogel matrix. The silica-containing calcium phosphate granules are preferably hydroxylapatite / silica granules, which optionally further comprise soluble calcium phosphate.
In general, synthesis for the production of calcium phosphates and also especially hydroxylapatite occurs in aqueous solution. (CPAt Klein, JMA De BlieckHogerworst, JGC Wolke, K. De Groot, Biomaterials,
11, 509 (1990)). Hydroxylapatite synthesis can occur in an alkaline medium and gives thermally stable, pure phase crystallites (M. Asada, Y. Miura, A. Osaka, K. Oukami, S. Nakamura, J. Mat.Sci. 23,<sup>3202</sup>(<sup>1988</sup>); <sup>S</sup>. Lazic, j. Cr<sup>s</sup>s<sup>t.</sup> Growth 1_47<sup>, 1</sup>47(<sup>1</sup>99<sup>5</sup>)). The synthesis of hydroxylapatite in a neutral or slightly acidic environment is also possible but more difficult to control (HEL Madsen, G. Thodvadarson, J. Cryst. Growth, 66<sup>,</sup>369(198<sup>4</sup>)).
When hydroxylapatite is to be obtained, it is derived, for example, from calcium nitrate and ammonium hydrogen phosphate at a ratio of calcium to phosphate of 10: 6 (US 5,858,318).
Other starting materials are NaHCCy and CaHPCa (Th. Leventouri, HY Moghaddam, N. Papanearchou, CE Bunachiu, RLLevinson, C. Martinez, <sup>M</sup>and<sup>t.</sup>Res.<sup>S</sup>oc.<sup>Sy</sup>m<sup>p</sup>.<sup>p</sup>roc. <sup>599,79</sup> (2<sup>000</sup>)) <sup>l</sup>at<sup>b</sup> Ca (<sup>H</sup>2<sup>pc</sup>4)2 <sup>and </sup>Ca<sup>cl</sup>2 (<sup>M</sup>.<sup>CKID</sup>about<sup>, R</sup>.Ic<sup>hi</sup>on<sup>,</sup> K.Kuro<sup>d</sup>and<sup>, R</sup>.<sup>ch</sup>sawa<sup>,</sup> C.<sup>T</sup>acai, <sup>M</sup>and<sup>vol. R</sup>es. <sup>S</sup>oc. <sup>Sy</sup>m<sup>p</sup>. <sup>p</sup>roc. <sup>599, 153</sup>(<sup>2000</sup>)). <sup>R</sup>motherboard<sup>and</sup>that in this case, when the hydroxylapatite is to be obtained, the calcium to phosphorus ratio of 1.67 is selected.
It is also possible to carry out a precipitation reaction with calcium milk and phosphoric acid (DE <sup>42 32 443</sup> C<sup>1, US 4,274,87</sup>9). <sup>J</sup>e<sup>sorry p</sup>about<sup>p</sup>slaughter <sup>t</sup>starting materials, e.g. hydroxylapatite, which can also be guided by the ratio of calcium to phosphorus starting materials, often dicalcium phosphate is formed as a byproduct, which is undesirable. It is therefore preferable not to use pure soluble starting materials and not to use lime milk (dispersion).
The cited literature describes how the parameters (pH value, homogeneity of the starting material mixture and temperature) affect the crystallite size and the degree of crystallinity of the final products. The relationship between the pH value and the temperature of the solution is particularly important (M. Ckido, R. Ichina, K. Kuroda, R. Chsawa, C. Takai, Mat. Res. Soc. Symp. Proc. 599, 153 (2000)). It is worth noting that hydroxylapatite in almost all solutions precipitates finely crystalline, i.e. as nanocrystals and for specific applications, e.g. as cleaning bodies for dental care, the process steps leading to larger crystallites are rather sought (DE 42 32 443 C1).
The amounts of starting materials are selected such that a Ca / P ratio of 1.50 to 1.67 is formed. The precipitation product is always so-called in this respect.
"Precipitated hydroxyapatite" (PHA. Ca10-x (HPO4) x (PO4) <sub>6</sub>x (OH) 2-x). In the course of further processing, also involving the action of temperatures at temperatures above about 650<sup>0</sup>C of "precipitated hydroxyapatite" partly produces completely hydroxylapatite when the calcium to phosphate ratio (Ca / P ratio) is exactly 1.67. At the Ca / P 1.5 ratio, almost all hydroxylapatite is converted to β-tricalcium phosphate. A mixture of tricalcium phosphate and hydroxylapatite is obtained by a Ca / P ratio between 1.5 and 1.67, the final composition of which is selected by the Ca / P ratio. Preferably the Ca / P ratio of 1.67 is chosen so as to preferably obtain only hydroxylapatite in the granulate. If the granulate is to contain soluble calcium phosphate (for in vivo use the pH value is 7), a Ca / P ratio less than 1.67 is chosen and soluble β-tricalcium phosphate is formed during the process.
Crystals in solution tend to agglomerate. If a solid separates out after precipitation, agglomeration of crystals, especially nanocrystals (DE 42 32 443 C1) cannot be avoided. Thus, granules are formed from calcium phosphate crystallites, from which the granules according to the invention can no longer be obtained in which the crystallites lie in a xerogel matrix.
According to the invention, this problem is solved by homogenizing the solution with precipitated calcium phosphate by stirring and adding a highly concentrated silicic acid solution, preferably orthosilicic acid. Preferably tetraethyloxysilane (TEOS) is used, which is completely hydrolysed. Preferably, TEOS and 0.1 M hydrochloric acid are mixed in a preferred 30: 9 volume ratio with vigorous stirring until hydrolysis. Hydrochloric acid solution provides water necessary for hydrolysis.
The ratio of calcium phosphate in the precipitated solution and the added silicic acid is chosen such that the granulate composition according to the invention is obtained from about 2% by weight to about 80% by weight silica. It should be noted in particular that 270 g of silica are formed from 1 liter TEOS. If, for example, a granulate is obtained which contains 30% by weight of silica, then for the solution with 100 g calcium phosphate 43 g silica is needed, which again means that about 160 ml TEOS is used. It is independent of how much solvent the precipitated solution contains.
According to the invention, the pH of the mixture of precipitated calcium phosphate and silicic acid is set in the range from 2 to 8, preferably in the range from 5 to 6.5.
The silicic acid in the slurry begins to condense and thus the viscosity of the mixture increases. Up to a viscosity of preferably 2x10<sup>5</sup> cP calcium phosphate sedimentation is inhibited by mixing.
The mixture is fixed by silica gel formation. Calcium phosphate crystallites now lie in a silica hydrogel matrix. By removing the solvent from the hydrogel matrix, the xerogel matrix of the invention is obtained. Since the granulate according to the invention has a granule grain size of from about 1 pm to about 1000 pm, comminution is necessary. This comminution preferably takes place in a hydrogel state.
The hydrogel is currently stored in a closed container, preferably at room temperature (possibly also at temperatures from about 60<sup>ABOUT</sup>C to about 80<sup>ABOUT</sup>C), preferably for a period of time from about 24 h to 48 h. During this time the silica gel ages, i.e. further condensation reactions take place in the solid gel.
The gel is then dried with calcium phosphate to remove the solvent. The drying temperature is preferably from about 20<sup>ABOUT</sup>C to about 150<sup>ABOUT</sup>C, preferably dried at about 120<sup>ABOUT</sup>C.
According to the invention, calcium phosphate / silica granules (hydroxylapatite / silica granules) are also obtained by freezing the moist hydrogel. By crystallizing water, calcium phosphate and silica hydrogel are compressed and form granulates, which are filtered off after melting the ice. The drained granules are preferably dried from about 20<sup>ABOUT</sup>C <sup>d</sup>oo<sup>k</sup>about<sup>L</sup>about <sup>15</sup>0<sup>0</sup>C <sup>k</sup>orz<sup>s</sup>s<sup>t</sup>n<sup>and</sup>ew <sup>120</sup>° <S.
A preferred embodiment of the granulate production according to the invention is characterized in that the mixture of precipitated calcium phosphate and silicic acid, whose pH value is set in the range from 2 to 8, preferably in the range from 5 to 6.5, is spray dried before gel formation. which has the advantage that granulate grain sizes are readily available in the range of the invention.
Sus ZENI spray is a known method in the art (see. For example. K. Masters, "Spray Drying", 2<sup>nd </sup>ed., John Wiley & Sons, New York, 1976).
During spray drying, liquid products are sprayed into fine droplets at the upper end of the drying tower. These drops during free fall are dried by a stream of hot air. The temperature of the hot air stream is between about 80<sup>ABOUT</sup>C and about 200<sup>ABOUT</sup>C and only works on products for half to one second. After freeze drying, spray drying is the second most industrially used non-damaging drying method, especially in the food industry.
If the applied condensation of silicic acid achieves a kinematic viscosity of preferably 0.5 to 50 cSt, the mixture is spray dried, the pressure is adapted to the concentration and viscosity so that granules 10 pm and smaller are formed (See Masters, Spray Drying Handbook , (1979), Geor<sup>g</sup> Him<sup>d</sup>in<sup>and</sup>n LU.).
By evaporating the solvent, gel formation is achieved and the transition from wet gel to xerogel is introduced. Spray drying works so that when the gel of small droplets is formed and the drying of small droplets is formed, granules of suitable size are formed.
The granulate is characterized in that calcium phosphate crystallites (preferably HA crystallites) are maintained by a porous silica gel.
Characteristics of the granulates are carried out using electron microscopy and photocorrelation spectroscopy (ER Pike and JB Abiss eds. Light Scattering and Photo Correlation Spectroscopy. Kluwer Academic Publisher,
1997) .
The effect of temperature on the granulate in the range from about 200 ° C to about 800 ° C, obtained according to one of the methods described above, ensures that the residual solvent is removed from the pores. In doing so, care must be taken that the available alcohol, if used as a solvent, is removed as completely as possible before exposure to temperature, otherwise the product will subsequently be contaminated at high temperatures by carbon formation.
Temperature action at around 700<sup>ABOUT</sup>C to about 900<sup>ABOUT</sup>C preferably (about 800<sup>ABOUT</sup>C in the presence of oxygen (normal air atmosphere)) removes any carbon that may be present by oxidation.
A particular embodiment of the granulate according to the invention comprises, as described above, 0.5 mol% to 35 mol% of the xerogel network modifier, preferably Na2O.
The network modifier is preferably introduced into the finished nanoporous granulate using preferably an aqueous solution. The drying process is preferably about 120<sup>ABOUT</sup>C to about 200<sup>ABOUT</sup>C then removes the solvent.
(Example: for 100 g of granules with 30% by weight of silica, 8 g of NaOH is dissolved in 50 ml of distilled water. The porous granulate takes this solution and is immediately dried to prevent the xerogel from dissolving in the basic solution) The granulate contains 21% by weight of oxide - network modifier, equivalent to 19.3 mol%
Na2O for xerogel.
The invention also relates to a process for producing the granules according to the invention in which, using suitable orthophosphate compounds and calcium compounds (e.g. calcium nitrate and ammonium hydrogen phosphate) by reaction of the PO4 orthophosphate group<sup>3</sup>- and calcium ions in an aqueous solution, hydroxylapatite precipitates, which has a Ca / P ratio of 1.50 to 1.67 due to the ion concentration set in the solution, with a Ca / P ratio of 1.67 being preferred when the final product as phosphate calcium should only contain hydroxylapatite, and a Ca / P ratio less than 1.67 is selected when the final product should additionally contain soluble β-tricalcium phosphate.
The method is further characterized in that the precipitated hydroxylapatite without forming agglomerates in an aqueous solution is uniformly embedded in a silicon hydrogel, which is obtained by introducing silicic acid, preferably orthosilicic acid, especially hydrolyzed tetraethyloxysilane (TEOS) into the aqueous solution and the pH value is set in the range of 2 to 8, preferably 5 to 6.5, such that gel formation occurs. The amount of TEOS used is selected such that the silica fraction is in the range from 4 to 80% by weight, preferably in the range from 2 to 50% by weight based on the total weight of the granulate grains.
Through the drying process, the hydrogel changes into xerogel, thanks to which calcium phosphate crystallites lie in the xerogel matrix.
According to the invention, the calcium phosphate granulate produced (insoluble calcium phosphate, which is preferably hydroxylapatite optionally in combination with soluble calcium phosphate, preferably β-calcium phosphate, which contains silica in a certain concentration and morphology, serves, as already mentioned, as the starting material for the preparation high porous bone replacement material. The method of manufacture is described below. Use as a starting material for coating implants by plasma spraying: (see RB Heiman, Plasma-Spray Coatings. Principles and Applications, Wiley-VCH Verlag (1998)). Parts that are in direct contact with the bone, such as the shaft of the hip prosthesis, are coated with the material. It is also possible to use with dental implants.
If the granulate mixes with the bone marrow fluid or the patient's own blood, then it is used as an injectable drug or medical product that is used to rebuild osteoporotic bones, to stimulate bone reconstruction in the transition area to loose metal implants, and to treat defects resulting from periodontitis.
The granules according to the invention produce a high porous bone replacement material according to the invention. A slurry is prepared from the granulate described and preferably water. Approximately 100 ml to about 300 ml of water are preferably used for about 100 g of granulate. After the pH is preferably adjusted to a range from 5 to 6.5, the layer is poured into any shape and dried. High-porous bone replacement material is obtained. The resulting shaped body is comparable to the body that is usually obtained in the ceramic method (for this, see: D. Richerson, Modern Ceramic Engineering, Dekker Publ., J. Reed, Principles of Ceramic Processing, Nanocrystalline Ceramics, M.
Winterer, Springer 2002).
Because in the calcium phosphate granulate according to the invention the calcium phosphate crystallites lie in a silica xerogel matrix, the surface of the granulate naturally consists of silica, which in the selected pH range tends to conduct condensation reactions between the -SiOH groups of the contacting granulate grains. Due to capillary pressure in the drying process, the granulate grain surfaces are compressed and bonded through -Si-O-Si- bonds. Thanks to this, the highly porous bone material obtains its mechanical durability and the described properties according to the invention. Silicic acid, especially orthosilicic acid, may be added to the slurry as an additional binder. According to one embodiment of the invention, TEOS is hydrolysed using hydrochloric acid and added to the slurry. For 100 g of granules, preferably 3 ml d is used<sup>about</sup> 15 ml TEOS.
The drying of the slurry preferably takes place at a temperature between about room temperature and about 200<sup>ABOUT</sup>C, particularly preferably between about 80<sup>ABOUT</sup>C and about 130<sup>ABOUT</sup>C. After drying, there is a further temperature treatment to strengthen the high porous bone replacement material at a temperature that depends on the availability of network modifiers in the xerogel granules. Without network modifiers (pure silica xerogel), the temperature treatment preferably takes place at about 7<sup>00</sup>°<sup>C</sup> to Fr.<sup>k</sup>about<sup>L</sup>about <sup>9</sup>° O<sup>0</sup>C <sup>k</sup>orz<sup>s</sup>s<sup>t</sup>n<sup>and</sup>hey<sup>s</sup> about<sup>k</sup>about<sup>L</sup>about <sup>800</sup>°<3. <sup>IN </sup>in the case of xerogel network modifiers, the temperature is preferably in the range between about 300<sup>ABOUT</sup>C and about 500 ° C.
The described high-porous bone replacement material obtains its described structure and thus the described properties.
In addition to nanopores, xerogel creates a pore category defined by the packing of granulate grains and their size. A further pore structure in the size range from several hundred pm to a millimeter area, which allows the blood vessels to grow, is produced in the molding by additionally adding organic powder with a grain size of the desired pore size later to burn, which after the drying process is fired.
Preferably, the pores (tubules) (in the size range from a few hundred pm to the millimeter area) are produced by introducing organic fibers of the desired diameter into the density, which are fired after the drying process.
Wax is particularly important as powder or fiber material, since then drying of the material, which always results in slight shrinkage, can be carried out at temperatures where the wax is soft and thereby prevents scratching of the material. The preferred drying temperature is about 40<sup>ABOUT</sup>C. Then the wax can be removed by centrifugation from the pores in about 100<sup>ABOUT</sup>C. In turn, wax residues are burnt out and around 800<sup>ABOUT</sup>The carbon formed is removed.
The method of producing the glass ceramics described according to the invention starts from the high porosity bone replacement material described.
The xerogel matrix of the high porous bone replacement material is converted into a glass matrix without sintering the calcium phosphate crystals together. This means that the silica tetrahedron linkage is complementary.
The gel-glass transition for pure silica requires a relatively high temperature from about 9OO<sup>about</sup>C to 1200<sup>ABOUT</sup>C. Since at these temperatures it is possible for the crystalline calcium phosphate components to perform a phase transition, it is preferable to use a high porous bone replacement material with a xerogel network modifier. The network modifiers are introduced either through the primary use of granules with the network modifier in the high porous bone replacement material or the network modifiers are introduced into the finished high porous bone replacement material using the same method as for the granulate. The glass transition occurs at much lower temperatures and the calcium phosphate component does not change. Typical concentrations of network modifiers are from 0.5 to 35 mole%, preferably 17 to 30 mole%, based on the silica fraction. Na2O is used as the oxide - network modifier, because the vitreous phase is soluble in the body fluid and can therefore also be resorbed.
Because the glass transition temperature of sodium silicate glass, depending on the sodium content, ranges from about 460<sup>ABOUT</sup>C to about 800<sup>ABOUT</sup>C, it is clear that heat treatment in this temperature range very quickly leads to glass. If the temperature treatment is carried out about 20% to about 5% below the glass transition temperature set for the composition, the process slows down, requires many hours and can be stopped at any time.
During resorption, the glass goes the opposite way. This means that the glass returns to a gel-like structure.
Thanks to the calcium phosphate / silica granules according to the invention, it is now possible to optimize the strength and resorption properties of the bone replacement material according to the invention. Increasing strength in each case goes hand in hand with deterioration of biodegradation.
Many uses are possible with the bone replacement material according to the invention. For minor defects, such as those found partly in maxillary surgery, granules of high porous bone replacement material can be used for restorations. For larger defects, where the remaining bone stabilizes the shape of the defect sufficiently, use fittings made of high-porous bone replacement material.
In particular, fittings in combination with mechanically more resistant bone replacement materials (matrix consists of glass) and more high porous bone replacement materials (matrix consists of xerogel) present an interesting application, especially in the case of larger defects or where no defects remain native bone as a guide rail.
According to the invention, these moldings have at least on one side a layer of resorbable inorganic bone replacement material with glass as a matrix (increased strength) and in this layer there are holes of the order of half to five millimeters in size, and the holes in this layer have a volume proportion of 5 to 80%. The total volume, including the holes, in the more resistant material is occupied by the material that has the xerogel as the matrix. The structure of the holes in the solid layer should allow the growth of blood vessels.
The invention therefore also relates to the use of the granules and bone replacement materials according to the invention for the production of shaped bodies, preferably a cuboid, plate, hollow cylinder or wedge. Furthermore, the invention allows the use of the aforementioned silica / calcium phosphate granulate to coat implants (see above). The coating is particularly preferably by plasma spraying.
The invention furthermore relates to the use of the granules according to the invention for the preparation of a medicament or a medical product, for the reconstruction of osteoporotic bone, for stimulation of bone reconstruction in the transition area to loose metal implants or for the treatment of paradontic defects. Preferably, the granulate is mixed with bone marrow liquid or blood.
The invention furthermore relates to a medicament or medical product which comprises granules according to the invention mixed with the bone marrow liquid or the patient's blood (thus autologously).
The invention furthermore relates to a medicament or medical product which comprises the high-porous bone replacement material or glass ceramic according to the invention as bone replacement material, wherein the bone replacement material is brought into contact immediately prior to implantation using a patient's bone marrow fluid or blood (thus autologously) so that the pores of the materials completely fill.
The present invention is further explained using examples and figures without limiting it.
Examples
Example 1
Preparation of calcium phosphate granules
3 mmol / m solution<sup>3</sup> Ca (H2PO4) 2 and a solution of 7 mmol / m<sup>3 </sup>The CaCl2 is mixed together (a Ca / P ratio of 1.67 is obtained) and the pH value is adjusted with NH4OH. Precipitated material is measured using powder diffractometry. Figure 4 shows the result. This is pure phase hydroxylapatite, which does not change during the next steps of the process.
In a solution with precipitated hydroxylapatite, sedimentation is prevented by constant stirring and concentrated until 50 g of hydroxylapatite per 100 ml of solvent remain. 60 ml of tetraethyloxysilane (TEOS) and 18 ml of 0.05 mol of hydrochloric acid are vigorously mixed until the hydrolysis of TEOS takes place, which requires about 15 min and is visible by increasing the temperature from room temperature to about 50<sup>ABOUT</sup>C.
This solution is brought to a solution with precipitated, homogeneously separated hydroxylapatite and the pH is adjusted to about 6.0 with NH4OH. This mixture is further mixed until a viscosity of about 2x10 is reached<sup>5</sup> cP (the solution becomes paste-like by following the silica gel formation). After immediate gel formation, the mixture is stored for 24 h in a closed vessel and then granulated.
This is followed by drying at 80<sup>ABOUT</sup>C for 2 h. The hydrogel will change into a xerogel.
The granulate is rinsed in distilled water and then dried again. In this case, the 120 temperature operation was selected<sup>ABOUT</sup>C for 2 hours.
Subsequent to this at a temperature of 800<sup>ABOUT</sup>C requires one hour. The resulting granulate consists of
75% by weight of calcium phosphate and 25% by weight of silica.
The resulting granulate is characterized by raster electron microscopy images, as can be seen in Fig. 5. Granulate grains can be recognized in the size range from 1 pm to 5 pm.
The granulate is made into a slurry using water and dynamic light scattering (ER Pike and JB Abiss eds. Light Scattering and Photo Correlation Spectroscopy. Kluwer Academic Publisher, 1997) to determine the granule grain size distribution. The result is given in Fig. 6.
Figures 7 and 8 show photos of cut through granule grains made by transmission electron microscope. The material was embedded in the epoxide and cuts about 60 nm thick were prepared. Krystality are plates with an average plate diameter of 150 nm and a plate thickness of about 10-20 nm. You can very well recognize how the crystallites are embedded in the xerogel matrix, although the contrast difference between the epoxy (embedding material) and the silica xerogel is only relatively weak. In Fig. 7 there is e.g. area A with epoxy-filled pores, and area B is a typical area in which hydroxylapatite is embedded in xerogel.
Example 2
Preparation of calcium phosphate granules
An aqueous solution of calcium nitrate and ammonium hydrogen phosphate with a calcium to phosphate ratio of 1.67 is mixed homogeneously using a magnetic stirrer and the pH value is adjusted with NH4OH. The precipitated material is washed four times with distilled water, centrifuged and then dispersed in ethanol.
With respect to the share of solids <sup>72.9 g</sup> HA, mixes p<sup>30</sup> m<sup>l</sup> T<sup>EOS</sup> from <sup>9</sup> m<sup>l 0.1</sup> mol / 1 HCl solution and 9 ml ethanol. After TEOS hydrolysis, this mixture is added to the HA slurry and distributed uniformly, and the pH is adjusted to 6.0.
Spray drying occurs, pumping through the nozzle a homogenised layer using compressed air and a pressure between 50 and 100 kPa, followed by rapid drying in a coaxial air stream at 100<sup>ABOUT</sup>C.
Subsequent temperature action at 800<sup>ABOUT</sup>C requires one hour.
The resulting granulate differs in properties from the granulate in the first place in the size of granule grains, which have a significantly narrower spread and the maximum is at a diameter of 18 μη.
Example 3
Preparation of calcium phosphate granules
An aqueous solution of 0.3 M phosphoric acid (H3PO4) is mixed with an aqueous suspension of 0.1 M calcium hydroxide (Ca (OH)<sub>2</sub>) in room temperature. A Ca / P ratio of 1.5 is obtained. The pH value is adjusted using NH 4 OH. The precipitated material is washed four times with distilled water and centrifuged, and then dispersed in water so that 50 g of calcium phosphate per 100 ml of solvent remain.
<sup>30</sup> m<sup>l</sup> THESE<sup>ABOUT</sup>S <sup>and</sup> 9 m<sup>l 0.05 M k</sup>wasu so<sup>l</sup>AD<sup>g</sup>axis<sup>loam</sup>n<sup>and</sup>e stirred until TEOS hydrolysis is carried out, which requires approx. 15 min. and this is evident by the increase in temperature from room temperature to about 50<sup>ABOUT</sup>C. This solution is brought into solution with precipitated homogeneously separated hydroxylapatite and the pH is adjusted to about 6.0 with NH4OH. This mixture is further mixed until a viscosity of about 2x10 is reached<sup>5</sup> cp (by following silica gel formation the solution becomes pasty). After immediate gel formation, the mixture is stored for 24 h in a closed vessel and then granulated.
This is followed by drying at 80<sup>ABOUT</sup>C for 2 h. The hydrogel will change into a xerogel.
The granulate is rinsed in distilled water and then dried again. In this case, the 120 temperature operation was selected<sup>ABOUT</sup>C for 2 hours.
Subsequent to this at a temperature of 800<sup>ABOUT</sup>C requires one hour. The resulting granulate consists of 86% by weight of calcium phosphate and 14% by weight of silica.
Figures 9 and 10 show photographs of granulate grain using a raster electron microscope. In fig. 9, the interior can be seen on the edge of the broken granulated grain. Fig. 10 shows the surface of the granulate grain. In this example, in tricalcium phosphate there are relatively large crystallites with a diameter of about 1 mm. The xerogel looks like a compact material in the photos, which naturally depends on the resolution of the raster microscope photos that do not fully represent the xerogel porosity. However, you can very well recognize how the xerogel forms a matrix in which the crystallites lie and all the granulate grain is surrounded by a xerogel layer.
Example 4
Manufacture of high porous bone replacement material
100 g of the granulate, the preparation of which is described in Example 1, containing 25% by weight of silica, is mixed with 150 ml of distilled water and poured into molds of 8 mm x 15 mm x 30 mm.
Drying takes place for 3 hours at 80<sup>ABOUT</sup>C. With the following temperature treatment, the samples are maintained for 2 hours at 120 hours<sup>ABOUT</sup>C, then the temperature is raised to 800<sup>ABOUT</sup>C and holds for 1 h.
The bone replacement material has a porosity of about
60%.
Fig. 11 shows an electronic raster image of the material. The granulate grains whose original shape can be seen in Fig. 5 now form a continuous three-dimensional structure with pores in the micrometer range.
The nanostructure inside the granulate remains unchanged.
Example 5
Manufacture of high porous bone replacement material
142 ml of water is mixed with 8 ml of TEOS hydrolyzed solution. For hydrolysis, 18 ml of 0.05 M hydrochloric acid are added to 30 ml TEOS and mixed until hydrolysis occurs, which can be recognized by increasing the temperature from room temperature to about 50<sup>ABOUT</sup>C.
100 g of the granulate, the preparation of which is described in Example 1, is evenly distributed in this solution. Further processing is as in the Example
4.
The additional material structure (micrometer and nanometer pores) does not change due to the additional introduction of silica. The granules are firmly bonded, which increases the overall strength of the high porous bone replacement material by about 50%.
Example 6
Manufacture of high porous bone replacement material but with macropores
Wax threads with a diameter of 0.2 mm completely disordered are introduced into the molds of Example 4 so that they fill a volume of 30% of the contents of the molds. To these forms, a slurry of silica-containing calcium phosphate granules is added as described in the Example
5. Drying currently takes place for 4 hours at 40 ° C, because the wax threads are soft, not yet liquid and do not separate into the resulting millimeter pores.
At temperature in 800<sup>ABOUT</sup>C burns for 1 hour.
The macropores formed in place of the wax threads occupy about 30% by volume such that the total porosity is 72% because the micrometric and manometric structure has not changed with respect to Example 5 or 6.
Example 7
Manufacture of glass ceramics
The starting point for the production of glass ceramics as bone replacement material is the high porous bone replacement material produced in Example 4.
The fitting made of this material has a density of 0.8 g / cm<sup>3</sup> and a porosity of about 60%. A volume of 1000 ml of the fitting contains 200 g of silica. To bring the network modifier to the xerogel shaped body with a volume of 1000 ml, 50 g NaOH is dissolved in 600 ml of water and introduced into the pores of the shaped body. The fitting completely sucks in the solution and then dries at 120<sup>ABOUT</sup>C. In the shaped oxide, the network modifier is 20% by weight, which corresponds to about 19 mol% Na2O with respect to xerogel.
The temperature is currently operating at 650<sup>ABOUT</sup>C for 2 hours. Thanks to this, the xerogel turns into a glassy state. A glass of sodium silicate is formed. The fitting shrinks and retains about 30% residual porosity.
The mechanical strength of bone replacement material is documented using Fig. 12. The A curve on the stress-strain diagram shows the material with silicon xerogel as the matrix. It is a material with 24% by weight silica and with hydroxylapatite as the crystalline component.
The B curve in the diagram shows a material with identical composition, where the xerogel matrix was made into glass. The breaking stress increased from about 3 to 50 MPa.
Example 7
In vivo study on high porous bone replacement material
Mining pigs from Göttingen were used for animal experiments to study the material's properties as bone substitutes. The animals were adults (1 year) and weighed between 25-30 kg. Bone defects exceed a critical value of 5 cm<sup>3</sup>; their dimensions are about 3.0 cm by 1.5 cm by 1.5 cm. They were placed in the lower jaw, filled completely with bone replacement material and closed again with the periosteum. After 8 months, the pigs were killed, the jaws were removed, and X-ray, histological and rastromicroscopic examinations were performed.
Fig. 13 shows a mandible with an old defect that was filled with the material of the Example 8 months after surgery. The defect area is clinically quite healthy. Histological studies show - based on many experimental animals - that less than 1% of biological material is in the defect range.
Fig. 14 shows a comparative test with an empty defect. This defect is surrounded by connective tissue and is not treated.
Fig. 15 shows a comparative study with commercially available bone replacement material based on hydroxylapatite. Although the defect is treated, the biological material does not break down and remains as a foreign body in the bone.
Fig. 16 shows a photo under the optical microscope of a histological section with eosin staining. You can recognize the lagoon (L) in the biomaterial of example (B). At the bottom of the lagoon are osteoclasts (O), which are about to break down biological material. This means that the biodegradation of the material occurs through osteoclasts, which is critical for use.
Example 8
Fig. 17 shows a fitting that combines the properties of both materials with different mechanical properties and is intended for major bone defects. Material with glass as a matrix forms on one side a supporting layer with a thickness of 2 mm, which has a hole pattern. The volume of the shaped body as well as the holes in the permanent layer are filled by the material with the xerogel as the matrix, because this material has better bioactive properties. Fig. 18 shows a further possible fitting. The cylinder has a fabric mantle with glass as the matrix. The coat also has a hole pattern that, like the entire volume, is filled with material with a xerogel as a matrix.
26 members in 15 offices
Priority claims8
| Document | Office | Kind | Date |
|---|---|---|---|
| 10323079 | Germany | A | |
| 10338634 | Germany | A | |
| 04739387 | European Patent Office (EPO) | A | |
| 2004005709 | European Patent Office (EPO) | W | |
| DE2003123079 | – | – | – |
| DE2003138634 | – | – | – |
| EP20040739387 | – | – | – |
| WO2004EP05709 | – | – | – |
Members26
| Document | Office | Kind | |
|---|---|---|---|
| AU2004241740A1 | Australia | A1 | |
| CA2537620A1 | Canada | A1 | |
| WO2004103421A1 | World Intellectual Property Organization (WIPO) | A1 | |
| DE10323079A1 | Germany | A1 | |
| DE10338634A1 | Germany | A1 | |
| EP1624904A1 | European Patent Office (EPO) | A1 | |
| HK1080766A1 | Hong Kong, China | A1 | |
| CN1826147A | China | A | |
| JP2006528894A | Japan | A | |
| EP1624904B1 | European Patent Office (EPO) | B1 | |
| AT350076T | Austria | T | |
| ATE350076T1 | Austria | T1 | |
| DE502004002554D1 | Germany | D1 | |
| US2007059379A1 | United States of America | A1 | |
| PT1624904E | Portugal | E | |
| DK1624904T3 | Denmark | T3 | |
| RU2005140093A | Russian Federation | A | |
| PL1624904T3This record | Poland | T3 | |
| ES2280969T3 | Spain | T3 | |
| US2008152723A9 | United States of America | A9 | |
| RU2354408C2 | Russian Federation | C2 | |
| CN100591365C | China | C | |
| AU2004241740B2 | Australia | B2 | |
| JP4764821B2 | Japan | B2 | |
| US8715744B2 | United States of America | B2 | |
| CA2537620C | Canada | C |
Numbers
- Publication, DOCDB
- 1624904
- Publication, EPODOC
- PL1624904T
- Application
- 739387
- Application, DOCDB
- 04739387
- Application, EPODOC
- PL20040739387T
Titles2
- English
- INORGANIC RESORBABLE BONE SUBSTITUTE MATERIAL
- Polish
- Nieorganiczny resorbowalny materiał zastępujący kości
Classification
- CPC, 6
- A61L27/427
- A61L27/12
- A61L27/56
- A61L27/58
- A61L2430/02
- A61P19/10
- IPC, 4
- A61L27 12
- A61L27 42
- A61L27 56
- A61L27 58