JPS61242978A - Vital body substitute ceramic material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a biosubstitute ceramic material that is implanted in a living body and used as a bone substitute, such as an artificial tooth root or an artificial bone.

(Prior art and its problems) Ceramic materials are easily compatible with living organisms and are resistant to corrosion, so they are expected to be used as biosubstitute materials for artificial tooth roots, artificial bones, etc., and various ceramic materials are being researched and developed. the current,
Various clinical cases have been demonstrated using these materials over the past 10 years.

Among them, apatite and tricalcium phosphate (TCP)
Despite their excellent biocompatibility, calcium phosphate ceramics such as these do not have sufficient strength to withstand the sudden impact and bending stress that occur when used as artificial bones and artificial tooth roots, making them insufficient as biosubstitute materials. be.

On the other hand, alumina single crystal or polycrystalline materials are suitable as biosubstitute materials, but they are inert to living organisms and have too high strength and hardness. It is well known that various problems have been occurring, such as inflammation between materials and alumina ceramics, or abrasion or abrasion of the mating material.

Therefore, in order to solve these problems, the center was made of alumina,
Composite materials whose surfaces are made of titanium metal, nickel metal, apatite, etc., which are easily compatible with living organisms, have been considered. However, these require considerable labor and process to create, and when combined, the adhesive layer does not have sufficient adhesive strength with the ceramic core, exposing the shortcomings of the material.

(Objective of the Invention) An object of the present invention is to solve the problems of the prior art described above.

(Process leading to the completion of the invention, structure of the invention, and effects of the invention) In view of the above circumstances, the inventors have been diligently researching biosubstitute ceramic materials, and have found that they are easily compatible with living organisms,
Furthermore, they discovered biosubstitute ceramics with sufficient strength as a biosubstitute material, found a material that achieved the desired clinical purpose, and succeeded in producing it.

In the first stage of the research, the above objectives were achieved by using bioinert polycrystalline ceramics with sufficient pores as the matrix, and by filling the pores with a material that is compatible with the living body. We have established a policy that this is an essential requirement for biosubstitute ceramic materials. As a result, the aforementioned bioinert polycrystalline ceramics can bear impact and stress, and the bonding with the living body can be achieved by the filling material that is easily compatible with the living body where new bone grows.

In the next research stage, we solved more specific problems as a biosubstitute ceramic material.

In other words, biocompatible ceramics are likely to be produced in many different types and in small quantities, so they need to be easy to mold. It also needs to be able to be molded into any shape. Therefore, the present inventors devised a porous matrix material that can be obtained by simultaneously nitriding and sintering silicon cast or hardened by rubber pressing in a nitrogen atmosphere. We came up with the idea of using sintered silicon nitride ceramics. This is the first feature of the present invention. This porous reactive sintered silicon nitride ceramic was used as the host material, and its specific gravity is around 2, which is approximately the same as that of living bone, and is appropriate in terms of weight.

The porous reaction sintered silicon nitride ceramic can be manufactured with a porosity in the range of 20 to 70%, and a material having an appropriate pore size can be manufactured. The strength varies depending on the porosity, so its value cannot be specified, but the maximum is 20-25 kg / m
r&, and can provide sufficient strength as an artificial bone substitute material (artificial bone is said to have a weight of 10 to 15 kg/m cd).

Here, the strength of currently available commercially available alumina single crystal or polycrystalline materials is 50 kg/mrr1.
Even with the above, when used as biosubstitute materials, these materials are completely inert, so new bone cannot be formed in the living body, and there is no interference layer between them and the living body, so the impact can be applied to these materials. When infected, it causes inflammation to the surrounding tissues, which is actually inappropriate.

The final research stage of the present invention was to solve the following problems. That is, although the above-mentioned material developed by the present inventors is also porous, it was necessary to solve the problem that if used as is, it would have the same drawbacks as alumina materials. Therefore, by performing the following treatment, it was made possible to act as a bioactive material.

That is, porous reaction sintered silicon nitride ceramics with collagen fibers dissolved in water, calcium phosphate-based apatite powder slurry, oxide powder slurry of titanium, molybdenum, tungsten, aluminum, etc., or mucopolysaccharide dissolved in water. A biosubstitute ceramic material was produced by filling and solidifying any one of these or a combination of two or more of these. This is the second feature of the present invention. Incidentally, instead of the collagen fiber solution, it is also possible to use other liquid filling substances that have the same properties and are compatible with living organisms.

The filling method may be to simply immerse the porous material in the solution or slurry, but this method often fails to sufficiently fill the porous material with the solution or slurry. Sufficiently filling the porous pores with the solution or slurry can be solved by placing the porous reaction sintered silicon nitride in a vacuum state and placing it in the solution or slurry, or conversely by pressurizing it and forcing it into the solution. can. In particular, most of the pores in porous reaction-sintered silicon nitride are open pores, and the structure allows the solution or slurry to penetrate sufficiently into the interior, which is also the reason for the present invention. The size of the pores at this time is preferably 5 to 200 microns, preferably 30 to 60 microns, from the viewpoint of the strength of the porous reaction-sintered silicon nitride and ease of immersion in the solution or slurry.

As mentioned above, the strength of the matrix porous reactive sintered silicon nitride material is the same or slightly higher than that of living bone, and is sufficient as aggregate strength. The structure of the material, or in other words, the pores, is filled with active substances such as collagen, calcium phosphate apatite, oxides such as titanium, molybdenum, tungsten, and aluminum, and mucopolymer compounds necessary for creating new bone in living organisms. Therefore, after implantation in a living body, new bone and ligament occur around the porous reaction sintered silicon nitride. Therefore, the inflammation that was feared with alumina does not occur due to the sudden impact after implantation of artificial bone, etc., and there is an absorption area that can withstand fE impact, making it fully functional as a biosubstitute material such as artificial bone. can be given.

As mentioned above, the porous reaction sintered silicon nitride may be cut out from a commercially available product.

However, in this case, since the material itself has high strength, processing will take a very long time. Porous reaction sintered silicon nitride is a material made by molding silicon powder and firing it in a stream of nitrogen gas. During this nitriding reaction, the shape and dimensions are almost the same as the original silicon made. Therefore, in terms of dimensional accuracy, post-processing after firing is not necessary. Some artificial tooth roots require threading. Even in such a case, if the silicon powder is molded into a predetermined shape at the time of molding, the shape after nitriding will be the same as the original size, so there is an advantage that no post-processing is required.

The concentration of the collagen liquid used to fill the pores of the matrix created in this way is 30 to 80%. If it is more dilute than this, after drying and solidifying, the amount that fills the pores of the reactive sintered silicon nitride material will be small, and even if it is implanted into the human body, effective new bone formation and calcification will not occur. . Since it is necessary for the collagenous material to sufficiently surround the pores, it is desirable that the collagen solution be concentrated. or,
The same thing can be said for mucopolysaccharide solutions, such as chondroitin solutions, and the solution concentration is preferably 30% or more.

When using calcium phosphate-based apatite powder and oxide powder of titanium, molybdenum, tungsten, aluminum, etc., the porous reactive sintered silicon nitride base material is placed in a vacuum and then immersed in a slurry of the above powder, or A method of pressurizing and press-fitting in a slurry is used.

For this purpose, it is better to have a fine powder particle size, and a fine powder of 10 μm or less, preferably 1 μm or less, is used.

It is better to have a higher slurry concentration of the powder, and a dilute slurry of 10% or less cannot perform sufficient powder filling. especially,
When using oxide powders of titanium, molybdenum, tungsten, aluminum, etc., it is better to partially reduce the surface of the powders so that they are compatible with living tissues.

(Example 1) 70 cc of 0.25% sodium alginate aqueous solution was added to 50 g of silicon powder (particle size: 325 mesh) as a dispersant.
After addition and mixing, this mixed slurry was poured into a Ceracola type (diameter 4 m) covered with a sodium alginate cellulose semipermeable membrane.
m, length 201 nI1) shape) and cast molded (about 30 pieces of the same shape were obtained). The molding density of the obtained silicon molded body was about 1.4 g/c+J.

This silicon molded body was nitrided in a mixed gas of Ni95%-H:5% according to the temperature schedule shown in FIG. 1 to obtain a porous reaction sintered silicon nitride ceramic. The density of this reaction sintered body is approximately 2.2 g/cJ (porosity: 32%
), and the bending strength was approximately 25 kg/m rd.

Using the porous reactive sintered silicon nitride ceramic obtained as above as a matrix, it is immersed in a 50% collagen fiber solution to fill the pores with collagen, and then dried and solidified. We created a biosubstitute ceramic material and used it in clinical experiments.

(Example 2) 30 g of the silicon powder of Example 1 was rubber pressed at a pressure of 3000 kg/cA. The density of the obtained compact is approximately 1
．． It was 2g/-. This silicon molded body was nitrided under the same conditions as in Example 1. The density of the reaction sintered body obtained at this time was about 1.9 g/c+d (porosity 41%), and the bending strength was about 20 kg/mm. A mother body of a dragon with a length of 12 dragons was cut out, immersed in a 70% chondroitin solution (an example of a mucopolysaccharide solution), dried, and then used in a clinical experiment.

(Example 3) The porous reactive sintered silicon nitride ceramic obtained in Example 1 was placed in a vacuum, and then immersed in a 50% hydroxyapatite powder (particle size: 0.5 μ) slurry,
After drying, it was used in clinical experiments.

(Example 4) A matrix with a diameter of 3 mII and a length of 12 m was cut out from the porous reactive sintered silicon nitride ceramic obtained in Example 2, and this was powdered with titanium oxide powder with a particle size of 1 μ (however, the surface was partially reduced). The specimens were pressurized and injected into a 70% slurry consisting of a 70% slurry of 100% polyester, and after drying, they were used in clinical experiments.

(Example 5) A porous reactive sintered silicon nitride ceramic having the same shape as in Example 4 was mixed with a 70% hydroxyapatite-molybdenum oxide-aluminum oxide powder slurry (hydroxyapatite; 50%, molybdenum oxide; 30%, aluminum oxide; After pressurizing and press-fitting in 20%) and drying,
Subjected to clinical experiments.

(Comparative example) The porous reaction sintered silicon nitride ceramic obtained in Example 1 was used as a biosubstitute ceramic material without treatment, and this was subjected to clinical experiments (Clinical experiment examples and results) Examples 1 to 1 above A clinical experiment was conducted by implanting the materials of No. 5 and Comparative Example into the lower jaws of dogs.

As a result, (Example 1), (Example 2), (Example 3)
, (Example 4) and (Example 5), biological tissue (
It was observed that it was well adapted to the mucosal epithelium and bone tissue and was firmly adhered.

On the other hand, in (comparative example), the conformation of the living tissue was approximately the same as in the above example, or slightly worse, but no adhesions as described above were observed.

[Brief explanation of drawings]

FIG. 1 is a graph showing a temperature schedule during nitriding in Example 1 of the present invention.

Claims (1)

[Claims] (1) Porous reactive sintered silicon nitride ceramics is used as a matrix, and in its pores, collagen fiber solution, calcium phosphate apatite powder slurry, oxide powder slurry of titanium, molybdenum, tungsten, aluminum, etc., mucopolysaccharide solution, A biosubstitute ceramic material obtained by filling and solidifying any one type of liquid filling substance that is easily compatible with living organisms, such as , or a combination of two or more of these substances.