JPH01115360A - Inorganic living body material and preparation thereof - Google Patents

Abstract

PURPOSE:To obtain a novel inorg. living body material having high strength and biologically active function, by dispersing crystallized glass having biologically active function in zirconia ceramics having high bio-compatibility, high strength and high toughness. CONSTITUTION:This inorg. living body material contains 12-56% CaO, 1-27% P2O5, 22-50% SiO2, 0-34% MgO and 0-25% Al2O3 on a wt. basis and is composed of composite ceramics prepared by dispersing crystallized glass 2 having a composition containing CaO, P2O5, SiO2, MgO and Al2O3 in an amount of 90% or more in total in zirconia ceramics 1 consisting of 1-100wt.% of partially stabilized Zirconia and 99-0wt.% of alpha-alumina in an amount of 5-50% on the basis of the total volume of crystallized glass and zirconia ceramics. This composite ceramics material contains CaO and P2O5 necessary for chemically bonding a bone and has high bending strength and is extremely useful as the living body material such as an artificial bone.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an inorganic biomaterial useful as an implant material for artificial bones, artificial tooth roots, etc., and a method for producing the same.

[Prior art and its problems] Ceramics have attracted attention as biomaterials because they are less harmful to living organisms than polymeric materials and metal materials, and their progress has been remarkable in recent years. Alumina ceramics have been put into practical use as artificial bones and artificial tooth roots, and are highly evaluated for their high strength, medical safety, and reliability. In addition, it has been reported that zirconia ceramics have higher strength and toughness than alumina ceramics, and have similar biocompatibility to alumina ceramics, and research toward practical use is progressing. However, since alumina ceramics and zirconia ceramics do not chemically bond directly to bone, there is a possibility that loosening may occur during long-term use, and several such clinical cases have been reported. On the other hand, among ceramics, so-called bioactive ceramics are known that create chemical bonds with bones, and in the case of such ceramics, loosening does not occur because they are integrated with the living body. Bioactive ceramics include apatite sintered bodies, Na20-20 MgOCa
OS i 02 P205 type crystallized glass is known. Also, Mg0-Ca OP 205 S 10
The 2-type glass is crushed to a particle size finer than 200 mesh, and the resulting glass powder is molded and then heat-treated in the sintering temperature range of glass powder, followed by apatite crystal [Ca1o(P
Crystallized glass produced by heat treatment in the formation temperature range of O2)6 (00,5,F)2 ] and wollastonite crystals [CaSiO3] is also known. In this crystallized glass, apatite crystals contribute to biocompatibility, and wollastonite crystals contribute to mechanical strength. Therefore, in order to increase the mechanical strength, it is desirable to increase the content of wollastonite crystals. Therefore, crystallized glass is also known in which the content of S i 02 is increased and the amount of precipitated wollastonite crystals is increased. Furthermore, recently, more than 200 meshes have been developed which precipitate apatite crystals and one or more alkaline earth silicate crystals selected from wollastonite, diopside, forsterite, okermanite, and anorthite by heat treatment. Zirconia is uniformly mixed into glass powder having a fine particle size in an amount of 5 to 50% by volume, and after the mixture is molded, the molded body is sintered to produce apatite crystals and one or two of the above-mentioned alkaline earth silicate crystals from the glass. A zirconia composite crystallized glass obtained by heat treatment in a temperature range in which seeds or more are precipitated is also known (see JP-A-62-231668). However, the bending strength of these ceramics is 1000 to 1400 kg/cJ for apatite sintered bodies, Na20-
20-MgO-CaO-3i 02 P205-based crystallized glass with 1000-1500 kg/cJ, M g
OCa OP205-3i02 type crystallized glass 12
It is about 00 to 1400 kg/-. In addition, Ca OP 20s S, which does not precipitate a large amount of wollastonite,
i 02 series or CaOP205 S i02
MgO, Y2O3 type crystallized glass is 1700-2300
It is about kg/ci. Furthermore, although zirconia composite crystallized glass has a relatively high bending strength of 2,300 to 3,300 kg/-, even the highest strength one has a bending strength of alumina ceramics (3,000 to 5,000 kg/-).
/-), and is not necessarily fully satisfactory as an artificial bone or tooth root.Currently, there are considerable restrictions on its usage, and it is difficult to use high strength and biological materials. There is a need for inorganic biomaterials with active functionality.

Therefore, an object of the present invention is to provide a novel inorganic biomaterial having high strength and bioactive properties.

[Means for Solving the Problems] The present invention achieves the above object by dispersing crystallized glass having a bioactive function in zirconia ceramics having high biocompatibility, high strength, and high toughness. The inorganic biomaterial of the present invention contains, on a weight basis, the above components in the following ranges: CaO 12-56% P2O5' 1-27% SiO2 22-50% MgO 0-34% Al2O30-25%; , P205, SiO
Crystallized glass having a composition in which the total content of MgO and Al2O3 is 2.90% or more is mixed with 1 to 100% partially stabilized zirconia and 99 to 0% by weight.
The present invention is characterized in that it consists of a composite ceramic in which 5 to 50% of crystallized glass and zirconia ceramics are dispersed based on the total volume in a zirconia ceramics consisting of α-alumina.

This inorganic biomaterial contains apatite crystals and one or more alkaline earth silicate crystals selected from wollastonite, diopside, forsterite, okermanite, and anorthite, and further contains β-triphosphate triphosphate. Calcium crystal [β-Ca3 (po4)2]
Contains as the case may be.

The composite ceramic constituting the inorganic biomaterial of the present invention utilizes the high strength and toughness of partially stabilized zirconia. The partially stabilized zirconia used in the present invention includes a small amount of Y2O3, MgO1Cab, CeO2
High strength and high toughness are achieved by utilizing stress-induced transformation (martensitic transformation) of tetragonal zirconia particles containing one or more of the following as a solid solution.
It shows a high strength of 000 k[/ca. In order to partially stabilize zirconia, one of the following on a molar basis with respect to ZrO2: Y203: 1, 5-5% MgOnia ~ 10% CaOnia ~ 10% CeO2: 4-15% Alternatively, two or more types may be dissolved in solid solution.

Furthermore, when α-alumina is combined with partially stabilized zirconia, the effect of microcracking is added, resulting in 150%
It shows a strength of 00 to 24000 kg/-. The ratio of partially stabilized zirconia to α-alumina is based on weight: partially stabilized zirconia 1 to 100%, α-alumina 99 to 0%
It is. However, if the content of partially stabilized zirconia is less than 10%, as shown in Example 2, the strengthening effect due to stress-induced transformation of zirconia is weak and is not effective in improving strength. Zirconia 1
0 to 100%, α-alumina 90 to 0%. A particularly preferable range is partially stabilized zirconia from 20 to 100%.
%, α-alumina 80-0%.

In the composite ceramic constituting the inorganic biomaterial of the present invention, crystallized glass having a bioactive function is dispersed in the zirconia ceramic. state

When the CaO content is less than 12% by weight, the amount of apatite crystals precipitated becomes extremely small. Moreover, when CaO exceeds 56%, the tendency of glass to devitrify becomes significant. Therefore, the content of CaO is limited to 12-56%. When P2O5 is less than 1%, the glass has a marked tendency to devitrify, and when it exceeds 1.27%, wollastonite, diopside, ) orsterite,
Since the amount of precipitated alkaline earth silicate crystals such as okermanite and anorsite is reduced, the content of P2O5 is 1.
~27%. If S i 02 is less than 22%, the amount of alkaline earth silicate crystals precipitated will be small. Moreover, if SiO2 exceeds 50%, the glass tends to devitrify. Therefore, the content of SiO2 is limited to 22-50%. MgO is not an essential component, but if it is included, the amount of apatite crystals produced will decrease if it is included.
% or less. Similarly, AI203 is not an essential component, but if it is included, the amount of apatite crystals produced will be reduced if it is more than 25%, so it is limited to 25% or less.

In addition to the five components listed above, glass also contains 20, L i 20 , N a 20 , T i O, which are not harmful to the human body.
2, ZrO2, S rO, Nb205, Ta205,
One or more of B203, F2, and Y203 may be contained within a range of 10%. If the total amount of these optional components is more than 10%, the amount of apatite crystals and alkaline earth silicate crystals produced may decrease, so it is preferably 10% or less. However, if F2 is more than 5%, the glass tends to devitrify, and if Y203 is more than 5%, the amount of apatite crystals and alkaline earth silicate crystals produced will decrease, so F2 and Y203 are Each is limited to 5% or less.

The amount of the crystallized glass having the above composition dispersed in the zirconia ceramic is limited to 5 to 50% based on the total volume of the crystallized glass and the zirconia ceramic. The reason for this is that if it is less than 5%, the effect of adding bioactive functions by compounding will hardly appear;
This is because if the amount is too large, the zirconia-based ceramic portion that becomes the skeleton will be reduced, and no improvement in mechanical strength can be expected. It is particularly preferable that the amount of glass is 5 to 30%.

The inorganic biomaterial of the present invention as described above contains, on a weight basis, the above components in the following ranges: CaO 12-56% P2O 51-27% SiO2 22-50% Mgo 0-34% A 1203 0-25% , P 205. S
Total content of iO2, MgO and AA203 is 90%
1 to 100% by weight of glass powder having the composition above and having a particle size finer than 200 mesh.
A zirconia-based powder consisting of partially stabilized zirconia and 99-0% α-alumina and having a finer particle size than the glass powder is mixed with 5-50% based on the total volume of the glass powder and zirconia-based powder. After molding this mixture into a predetermined shape, apatite crystals and alkaline earth silicate crystals selected from wollastonite, diopside, forsterite, occlumite, and anophresite are extracted from the glass in this molded body. It can be produced by heat treatment in a temperature range where zirconia-based powder precipitates, and then heat treatment in a sintering temperature range of zirconia-based powder.

In producing the inorganic biomaterial of the present invention, glass having the composition range defined above is first ground to a particle size finer than 200 mesh (74 μm or less). It is particularly preferred that the particle size of the glass is 2500 to 625 mesh (5 to 20 μm). Next, this glass is uniformly mixed with zirconia-based powder, the obtained mixed powder is molded into a desired shape, the glass portion in the obtained molded body is subjected to a crystallization treatment, and then the zirconia is sintered. That is essential. In composite ceramics, glass parts having a grain size coarser than 200 mesh often become defects, making it impossible to obtain composite ceramics with high mechanical strength. In other words, in order to obtain a composite ceramic in which crystallized glass is uniformly distributed in the zirconia ceramic, it is necessary to
It is important to use a fine glass powder with a particle size finer than 00 mesh.

As shown in FIG. 1, the inorganic biomaterial of the present invention has a skeleton of zirconia ceramics 1, and has crystallized glass 2 dispersed therein to improve its strength. If the zirconia powder is larger than the glass powder, the particles of the zirconia ceramic 1 will be covered with the crystallized glass 2 as shown in Figure 2, resulting in a structure with the crystallized glass as the skeleton. It is not possible to obtain a composite ceramic with a structure that serves as a skeleton, and it is not possible to take advantage of the high strength and high toughness characteristics of zirconia ceramics. Therefore, it is essential that the zirconia powder used has a finer particle size than the glass powder. Wet synthesis using a coprecipitation method, a hydrolysis method, an alkoxide method, etc. can yield fine zirconia-based powders of 1 μm or less, but such fine zirconia-based powders are not suitable for obtaining the composite ceramics of the present invention. be.

According to the method of the present invention, a glass powder having a particle size finer than 200 mesh and a zirconia powder having a particle size even finer than this glass powder are mixed and molded by any known means, and then a molded body is formed. The zirconia
Heat treatment is performed in a temperature range where apatite crystals and alkaline earth silicate crystals are precipitated from the glass in the glass mixed powder, and then heat treatment is performed in a zirconia sintering temperature range (usually 1200° C. or higher). However, if the sintering temperature exceeds 1500°C, the crystallized glass portion may melt and form pores.
Since it may react with zirconia and lose its bioactive function, a sintering temperature of 1200 to 1500°C is preferable. The former heat treatment is important for precipitating apatite crystals and alkaline earth silicate crystals from the glass;
The latter heat treatment is important for obtaining composite ceramics with few pores and high mechanical strength.

The precipitation temperature range of apatite crystals and alkaline earth silicate crystals is determined by differential thermal analysis of a zirconia-glass mixture. By analyzing the X-ray diffraction data of the zirconia-glass mixed powder heat-treated at the temperature of the exothermic peak in the differential thermal analysis curve, the precipitated crystals corresponding to each exothermic peak were identified, and the temperature from the exothermic temperature to the exothermic end temperature was determined. The precipitation temperature range for each crystal.

Further, the sintering temperature range can be determined by heating a molded body of zirconia-glass mixed powder at a constant rate and measuring the thermal contraction during the heating. The sintering temperature range is from the start temperature to the end temperature of thermal contraction.

Any known method may be used as the heat treatment method, but if a hot press method or IP (hot isostatic pressing) method is used, sintering will be further promoted, pores will be reduced, and mechanical strength will be greater. You can get something.

[Examples] Hereinafter, the present invention will be further explained with reference to Examples, but the present invention is not limited to these Examples.

Example 1 CaO 47.8%, Si
02 44.0%, MgO1.5%, P2O56.5%
, prepare a batch of glass to have an F20.2%,
This was placed in a platinum crucible and melted at 1550°C for 2 hours.

Next, the melt was poured into water, dried, and then placed in a ball mill and ground to a particle size of 20 μm or less (625 mesh or more) to obtain a glass powder. It was added to a fine zirconia powder (average particle size 0.3 μm) consisting of partially stabilized zirconia containing mol % of Y2O3 and not containing α-alumina, further wet-mixed using a ball mill for several hours, and dried. was given,
A large number of mixtures of zirconia fine powder and glass powder with different blending ratios were each put into a graphite mold, and 300 kg/-
Heating from room temperature to 1200℃ at a constant temperature increase rate of 3℃/min while applying
The molded body was crystallized and sintered by holding for a certain period of time. Thereafter, it was cooled to room temperature in a furnace to obtain a composite ceramic.

The relative specific gravity of each composite ceramic thus manufactured was 9
It was 8% or more. Furthermore, when these composite ceramics were crushed and the precipitated crystal phase was identified by powder X-ray diffraction, apatite and wollastonite were precipitated from the glass. Furthermore, we added composite ceramics to 3X4X36mm.
A three-point bending strength test was conducted according to JIS R1601. The relationship τ between the crystallized glass content layer (#%) contained in the composite ceramic and the three-point bending strength is shown in Figure 3. As is clear from the figure, the inorganic biomaterial of this example, which is made of a composite ceramic in which 5 to 50 volume percent of crystallized glass is dispersed in zirconia ceramics, has a bending strength of up to 14,000 kg/-, which is It has a much higher bending strength than inorganic biomaterials with bioactive functions.

"Example 2 Using co-oxides, carbonates, phosphates, hydrates, fluorides, etc. as raw materials, CaO47.8%, SiO2
44.0%, MgO1.5%, P2O56.5%, F
A batch of glass was prepared at a concentration of 20.2%, placed in a platinum crucible, and melted at 1550° C. for 2 hours.

Next, the melt was poured into water, dried, and then placed in a ball mill and pulverized to a particle size of 20 μm or less (625 mesh or more) to obtain glass powder. This glass powder was added to a zirconia-based fine powder (average particle size 0.3 μm) consisting of partially stabilized zirconia containing 3 mol% Y203 and α-alumina obtained by a coprecipitation method. The mixture was wet-mixed using a ball mill for several hours, and then dried. Each of the obtained mixtures with different blending ratios of partially stabilized zirconia and α-alumina was placed in a graphite mold and heated at 300 kg/cJ.
While applying a pressure of
The molded body was crystallized and sintered by holding for a certain period of time. Thereafter, it was cooled to room temperature in a furnace to obtain a composite ceramic.

The relative specific gravity of each composite ceramic thus manufactured was 9
It was 6-99%. Furthermore, when these composite ceramics were crushed and the precipitated crystal phase was identified by powder X-ray diffraction, apatite and wollastonite were precipitated from the glass. Furthermore, we added composite ceramics to 3x4x36m.
It was processed into a square column of m in diameter and subjected to a three-point bending strength test in accordance with JIS R1601. FIG. 4 shows the relationship between the α-alumina content (weight percentage) contained in the zirconia ceramics and the three-point bending strength. As is clear from the figure,
α-alumina content in zirconia ceramics is reduced to 0.
The inorganic biomaterial of this example varied over ~99% by weight has a bending strength of up to 15000 kg/-,
It has a much higher bending strength than conventional inorganic biomaterials with bioactive functions.

[Example 3 Using cooxides, carbonates, phosphates, hydrates, fluorides, etc. as raw materials, a batch of glass corresponding to the composition shown in Table 1 was prepared, and this was placed in a platinum crucible. te1450~15
It was melted at 50°C for 2 hours.

Next, the melt was poured into water, dried, and then placed in a ball mill and pulverized to a particle size of 20 μm or less (625 mesh or more) to obtain glass powder. This glass powder was added to fine zirconia powder (average particle size 0.3 μm), which was made of partially stabilized zirconia containing 2.5 mol% Y2O3 and did not contain α-alumina, obtained by the coprecipitation method. The mixture was wet-mixed using a ball mill for several hours, and then dried.

Each of the obtained mixtures with different glass compositions was put into a graphite mold, and while applying a pressure of 300 kg/ad,
The molded body was heated from room temperature to 1200°C at a constant temperature increase rate of 3°C/min and held at 1200°C for 2 hours to crystallize and sinter the molded body. After that, it is cooled to room temperature in the furnace,
Composite ceramics were obtained.

The relative specific gravity of each composite ceramic thus manufactured was 9
It was 8-99.5%. Furthermore, these composite ceramics were ground, and the precipitated crystal phase was identified by powder XuA diffraction. Further, the composite ceramic was processed into a 3 x 4 x 36 mm square column, and a three-point bending strength test was conducted in accordance with JIS R1601.

Table 1 shows the glass composition, crystal phase precipitated from the glass, and three-point bending strength. As is clear from the table, the inorganic biomaterial of this example also has a much higher bending strength than conventional inorganic biomaterials having bioactive functions.

(Blank below) "Effects of the Invention J The inorganic biomaterial of the present invention contains CaO and P2O5, which are necessary for chemically bonding with bone, and has an extremely high level of bioactivity compared to conventional materials. Since it has bending strength, it is extremely useful as a biomaterial for artificial bones and artificial tooth roots.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the interior of the inorganic biomaterial of the present invention, which is made of a composite ceramic obtained using zirconia powder having a particle size finer than that of glass powder as a starting material;
Figure 2 is a schematic diagram of the interior of a comparative inorganic biomaterial made of composite ceramics obtained using zirconia powder with a coarser particle size than glass powder as a starting material;
The figure shows the relationship between the crystallized glass content (volume percentage) contained in composite ceramics and bending strength. Figure 4 shows the α-alumina content contained in zirconia ceramics.
It is a relationship diagram of f1 (weight percentage) and bending strength. 1... Zirconia ceramics 2... Crystallized glass

Claims (2)

[Claims] (1) Contains the above components in the range of CaO 12-56% P_2O_5 1-27% SiO_2 22-50% MgO 0-34% Al_2O_3 0-25% on a weight basis, CaO, P_2O_5, S
The total content of iO_2, MgO and Al_2O_3 is 9
Crystallized glass having a composition of 0% or more is mixed into a zirconia-based ceramic consisting of 1-100% partially stabilized zirconia and 99-0% α-alumina on a weight basis, and the crystallized glass and zirconia-based ceramic An inorganic biomaterial characterized in that it consists of a composite ceramic in which 5 to 50% of the total volume of the composite ceramics is dispersed. (2) Contains the above components in the range of CaO 12-56% P_2O_5 1-27% SiO_2 22-50% MgO 0-34% Al_2O_3 0-25% on a weight basis, and contains CaO, P_2O_5, S
The total content of iO_2, MgO and Al_2O_3 is 9
Glass powder having a composition of 0% or more and a particle size finer than 200 mesh, on a weight basis
A zirconia-based powder consisting of 0% partially stabilized zirconia and 99-0% α-alumina and having a finer particle size than the glass powder is added with 5-50% based on the total volume of the glass powder and the zirconia-based powder. After mixing and shaping this mixture into a predetermined shape, apatite crystals and one type of alkaline earth silicate crystals selected from wollastonite, diopside, forsterite, okermanite, and anorthite are extracted from the glass in this molded body. Alternatively, a method for producing an inorganic biomaterial, which comprises heat-treating in a temperature range where two or more types precipitate, and then heat-treating in a sintering temperature range of zirconia-based powder.