JP2579212B2 - Polycrystalline alumina ceramic for living body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to polycrystalline alumina ceramics for living bodies which can be densely sintered and have excellent biocompatibility. An object of the present invention is to provide an alumina ceramic which is used as an artificial bone, an artificial joint, an artificial tooth root, or the like, which is directly implanted or in contact with a human body to recover and enhance biological functions.

[Conventional technology]

Bioceramics such as artificial bones made of high-purity alumina single crystals of about 99.9% by placing a high-purity alumina raw material in a heat-resistant container and melting it in a vacuum are known as alumina ceramics for living bodies. Kuniaki 61-90
No. 74, etc.). Further, as an alumina polycrystalline bioceramic, there is known a fired ceramic composition for an intraosseous implant, which comprises 50 to 95% of alumina and ZrO ₂ or the like (Japanese Patent Publication No. 51-39654).

Further, as a high-purity alumina ceramic in the field of electronic components, etc., it is composed of a three-component system of Al ₂ O ₃ —SiO ₂ —MgO,
₂ O ₃ containing 99.7 to 99.9% by weight and having a small high-frequency dielectric loss (Japanese Patent Publication No. 63-66795); Al ₂ O ₃ —CaO—MgO 3
A high-frequency high-frequency Q-factor comprising 99.6 to 99.9% by weight of Al ₂ O ₃ (JP-A-61-118905) is known.

[Problems to be solved by the invention]

In the first alumina ceramic for a living body,
High alumina content but for single crystals.
On the other hand, polycrystalline alumina is hardly studied because high-purity alumina becomes difficult to be sintered. Only those having low alumina purity, such as those for the second intraosseous implant, have been studied.

On the other hand, alumina ceramics used for the above electronic components and the like are made of polycrystalline alumina in view of the manufacturing method. But,
When this is used in a living body for a long period of time, it is important that it does not adversely affect the living body, but there is no mention of what composition of alumina ceramics is suitable for the living body.

The present invention solves the above problems and, as a result of various studies, newly finds that high-purity polycrystalline alumina having a certain composition is extremely excellent in cell growth, and a dense sintered body is obtained. It is an object of the present invention to provide a polycrystalline alumina ceramic for living organisms which is not harmful to living organisms and has extremely excellent biocompatibility.

[Means for solving the problem]

The biological polycrystalline alumina ceramic of the present invention is a biological polycrystalline alumina ceramic which is fired at 1250 to 1650 ° C. in an air atmosphere, the aluminum oxide content is 99.5 to 99.9% by weight, and the balance is Mg, Ca,
It consists of one or more oxides and unavoidable impurities selected from Sr, Ba, Sc, Y, La and Ce, and consists of a polycrystalline sintered body, and the cell concentration of L-929 cells is 2.8 × 10 ⁴ Cell / ml. When cultured on the above-mentioned polycrystalline alumina ceramics plate using 3.1 ml of a medium, the cells have a cell growth property such that the number of cells three days after seeding at 37 ° C. becomes 8.5 × 10 ⁴ or more. .

The “L-929 cells” used in the evaluation of cell proliferation in the present invention are a kind of L cells, and include CCL1 (N
CTC clone 929).

As a result of various studies, the present inventors found that the alumina content was 9%.
9.5% or more of polycrystalline alumina ceramics is extremely excellent in cell growth, and in order to sinter it densely,
New knowledge has been obtained that an alumina material with higher sinterability and higher purity may be used and an appropriate auxiliary agent may be selected.

That is, with the above composition, it is possible to obtain a sintered body that is dense and has high strength as well as cell growth and that is not harmful to living organisms.

The reason why the alumina content is set to 99.5% or more as described above is that the growth by cell culture is excellent, and the biocompatibility is extremely excellent. In particular, the alumina content is 99.7
%, More favorable cell proliferation can be obtained. Further, the use of at least one of oxides of Mg, Ca, Sr, Ba, Sc, Y, La and Ce is because it is excellent as a sintering aid for alumina and has almost no harm to living organisms.

On the other hand, the upper limit of alumina content is 99.9%
If it exceeds 9.9%, it is difficult to obtain a more superior cell growth and it is difficult to perform stable sintering. If it is in the range of 99.5 to 99.9%, the desired polycrystal can be obtained. That's why.

Furthermore, in the manufacturing process from the preparation of the raw material of the sintered body to the firing, there is a danger that inevitable impurities may be mixed.
0.1% or less is preferable. The average particle size of the alumina used is preferably about 0.1 to 1 μm in terms of easy sintering and easy production. The firing temperature is in the range of 1250 to 1650 ° C., and in order to further suppress grain growth as sufficiently as possible and sufficiently maintain the density, and preferably in the range of 1350 to 1500 ° C.

〔Example〕

Hereinafter, the present invention will be described specifically with reference to examples. Alumina (purity 99.999%, average particle size 0.5μ), magnesium carbonate (commercially available, special grade reagent), calcium carbonate (commercially available,
Reagent grade), strontium carbonate (commercially available, reagent grade), barium carbonate (commercially available, reagent grade), scandium oxide (commercially available, grade reagent), yttrium oxide (commercially available, grade reagent), lanthanum oxide (commercial grade, Reagent grade),
Ten kinds of cerium oxide (commercially available, special grade reagent) and nickel oxide (NiO) were used, and four kinds of carbonates were MgO and Ca, respectively.
In terms of O, SrO, BaO, so that the total amount is 1 kg each,
Weigh and mix each proportion in the table. Thereafter, water, 1 g of polyvinyl alcohol and 5 g of polyethylene glycol were added to the mixture, and mixed for 2 hours using a polyethylene pot having an internal volume of 2 liters and 2 kg of alumina spheres having a purity of 99.995%. The 19 types of slurries thus obtained were freeze-dried and then granulated with a 60-mesh sieve.

The granulated powder was formed into a predetermined size by a 1500 kg / cm ² mold press, and fired in an air furnace at 1250 to 1600 ° C. for 1 hour to obtain a sintered body. Analytical values of chemical components of this sintered body,
The results of density, flexural strength and number of cells after 3 days are shown in the table. Nos. 1 to 14 are products of the present invention, and Nos. 15 to 19 are comparative examples.

The bending strength was measured according to JISR1601 using a sintered body of 3 × 4 × 40 mm. For cell growth, cell concentration was 2.8 × 10 ⁴ Cell
3.1 ml / ml of the medium was cultured on the sample at 37 ° C., and the number of cells on the sample was counted every day from seeding. In addition, L-929 was used as a cell. The results of these cell growth tests are shown in FIG.

As shown in the table, the alumina content is 99.5% or more and
MgO, CaO, SrO, BaO, either _{Sc 2 O 3, Y 2 O} 3, La 2 O 3 and optionally with the addition of at least one CeO ₂ (No.1~14) is
A good dense sintered body on 3.92 g / cm ³ can be obtained under normal firing conditions, and the bending strength is 52 kg / mm ² or more and 98.4
% (No. 17) or more than 99.3% (No. 15).
~ 18) showed better biocompatibility.

When NiO was added and the alumina content was 99.6% (No.
In 19), the bending strength and the cell growth rate were not good even though the alumina content was included in the range of the present invention. This shows that the difference from the above composition range of the present invention is large in that the addition of a small amount causes a decrease in cell proliferation. Further, Ni has a problem in terms of harmfulness to living organisms, while the above-mentioned CaO and the like do not have such a concern.

[Effect of the Invention] The present invention can produce a dense, high-strength sintered body that is not harmful to living organisms even in a polycrystalline sintered body by mixing a predetermined amount of a predetermined additive such as Mg with a high alumina content. In addition, the cell growth rate of this sintered body is extremely excellent. Therefore, the present sintered body is very preferable for a living body.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the alumina content and the number of cells after 3 days.

Claims (1)

(57) [Claims] 1. A biological polycrystalline alumina ceramic fired at 1250 to 1650 ° C. in an air atmosphere, wherein the content of aluminum oxide is 99.5 to 99.9% by weight and the balance is Mg, Ca, Sr, It is made of one or more oxides and unavoidable impurities selected from Ba, Sc, Y, La and Ce, and is made of a polycrystalline sintered body. The cell concentration of L-929 cells is 2.8 × 10 ⁴ Cell / ml. Culture value 3.
When cultured on the above polycrystalline alumina ceramics plate using 1 ml, the number of cells 3 days after seeding at 37 ° C.
A biological polycrystalline alumina ceramics having a cell proliferation of 8.5 × 10 ⁴ or more.