JPH0634795B2 - Composite implant and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improved implant.

[Conventional technology]

The biomedical implant member is liable to undergo changes such as deterioration and destruction due to dissolution and corrosion in a harsh environment in the living body, and is accompanied by a foreign body reaction. Therefore, a material that is chemically stable and has high mechanical strength is required.

By the way, as a biomedical implant member, a metal material, an organic material, an inorganic material and the like have been conventionally used, but each has its advantages and disadvantages.

That is, stainless steel, Co-Cr-Mo alloys, metallic materials such as titanium are rich in workability and formability, and are tough as a feature of mechanical properties, have large fracture toughness, but have poor biocompatibility, and There is concern about elution of metal ions.

Organic materials such as acrylic resin, polyurethane, and MMA (methyl methacrylate) are excellent in processability and chemical resistance, but have poor mechanical properties, have no heat resistance, and have a risk of deformation and thermal decomposition.

On the other hand, although inorganic materials such as ceramics and glass have good biocompatibility and corrosion resistance and sufficient hardness, they have drawbacks of low fracture toughness and brittleness and poor workability.

In order to make use of the advantages of each of these materials and to make up for the shortcomings,
Various attempts have been made so far. Particularly recently, research and development on a wide variety of composite implants by various coating methods such as coating of hydroxyapatite on the surface of ceramic materials such as alumina and zirconia and coating of glass and ceramics on the surface of various metals such as stainless steel have been actively conducted. Has been done.

[Problems to be Solved by the Present Invention]

However, at the present time, all of the above-mentioned various composite implants have insufficient bonding strength between the substrate and the coat layer, resulting in peeling or cracking, or on the other hand, even if the bonding strength is sufficient, compared to single use. The overall binding strength with the bone was quite poor. This is due to the difference in the physical properties of each material due to the compounding-that is, heat resistance, thermal expansion coefficient, bondability, surface stability, and the like.

For example, in the case of hydroxyapatite coating on the surface of alumina ceramics, because the coating is performed under high temperature such as thermal spraying, the total binding force between the coated apatite and the bone depends on the quality of the apatite and the like. It has been confirmed so far that it is considerably inferior to the binding force with.

Attempts to coat metal with apatite
58-39533), but there were problems with deterioration due to metal oxidation and bonding strength.

As one of the methods to solve these problems, Fe-Cr-Al alloy having α-alumina deposited on the surface has been recently developed. This is also a biological hazard due to the elution of alloy component ions. Remains anxious about. Therefore, by combining a metal material with excellent mechanical properties and bioactive ceramics that has a very high affinity for living tissue and bone tissue, the bonding strength is excellent and sufficient bond strength is maintained even when bonding to bone. It is intended to bring a composite implant that is present.

[Means for solving problems]

As a result of intensive studies conducted by the present inventors in view of the present situation, as the implant substrate, a biomedical metallic material such as pure titanium and titanium alloy having particularly excellent corrosion resistance is used, and an aluminum thin film is known on the surface thereof. A porous oxide film is formed on the surface of the implant by coating it by a method and then anodizing it. Then, after expanding and controlling this pore size, we have developed a high-performance composite implant that has never existed before by filling or coating the bioactive material by dipping or coating.

Here, the bioactive material refers to a material which has a good affinity with living tissues and a strong chemical bond with surrounding hard tissues. The bioactive material used in the present invention includes:
In addition to conventionally used synthetic hydroxyapatite and biological hydroxyapatite, TcP, calcium-
Examples thereof include bioglass such as phosphoric acid-based crystallized glass, but are not necessarily limited to these, and any substance that is not harmful to living organisms and has excellent affinity and reactivity with living organisms can be used. It can be used.

Examples of the present invention based on titanium will be specifically described below, but the present invention is basically applicable to all biomedical metallic materials that can be coated with Al.

Example 1 An aluminum alloy (Al) was formed on the surface of a pure Ti dental implant having a desired shape by a high-speed sputtering method.
Was coated to 5 to 7 μm. This was washed with degreased water and then anodized in a 15% sulfuric acid solution at a constant voltage of 20 V at 15 to 20 ° C. for 20 to 30 minutes. The pore size of the thus obtained γ-Al ₂ O ₃ porous material was about 200Å as a result of electron microscopic observation.

Next, this porosity is chemically dissolved with 20% sulfuric acid to reduce the pore size to about 50.
Expanded to 0Å. Then, in advance, set the crystal grain size to 50.
Disperse synthetic hydroxyapatite adjusted to ~ 350Å in a 1: 1 volume ratio of water: alcohol mixed solution to give 10 ~ 100
Electrolysis treatment by an electrophoretic method was performed under a voltage of V for several tens of seconds to several minutes.

As a result, apatite crystal particles were electrodeposited in the fine pores of the γ-Al ₂ O ₃ porous layer on the surface of the implant.

[Experimental Example 2] The surface of an alloy titanium Ti-6Al-4V orthopedic implant was coated with Al by the ion plating method for 8 to 10 μm. After washing this with degreasing water, in a 4% phosphoric acid solution
Anodization was performed under the conditions of 80 V, 15 to 20 ° C. and 5 to 10 minutes.

In this case, the pore size of the obtained porous layer was about 500Å.

Next, this was chemically dissolved with 3 NHcl and the pore size was controlled to be expanded to about 1000 Å. The implant having a porous layer on the surface thus obtained was subjected to a voltage of 10 to 100 V in an aqueous suspension containing 5 to 20% of colloidal synthetic hydroxyapatite.
Secondary electrolysis was performed for 0 seconds to 10 minutes.

Then, the implant was washed with distilled water, dried, and then immersed in an aqueous solution of aluminum phosphate. Then, for heating dehydration, baking was performed at 300 to 400 ° C. for 1 minute to 1 hour.

As a result, the porous aluminum oxide coating layer produced by anodic oxidation of the implant surface is completely filled with the apatite particles attached by the subsequent electrophoretic treatment, and the surface has heat resistance and water resistance. It was covered with a strong coat layer.

Example 3 By the same method as in Example 2, an alloy titanium dental implant having a porous anodic oxide film on its surface was obtained.

Next, this solution was added to physiologically saline and a trace amount of an acrylic peptizer to ultrafine powdery aquatic apatite, and immersed in a sol-like solution to be sufficiently impregnated. After the impregnation, the surface was cleaned, air-dried, and then baked at about 450 ° C. for 30 minutes to 1 hour.
As a result, a high density apatite coat layer having scratch resistance and high durability was obtained on the surface of the implant.

[Example 4] The surface of a pure titanium implant material was coated with aluminum using an ion plating device so as to have a thickness of 20 to 25 µm.

Next, the implant was anodized in a molten salt bath of NaHSO ₄ —NH ₄ HSO ₄ system under a voltage of 100 to 150 V for 10 minutes to 1 hour. The anodic oxide film obtained as a result was an α film having a pore size in the range of about 1000Å to 1 µ.

Next, this was chemically dissolved with 5% hydrofluoric acid, and the pore size was finally controlled to 1-2 μm. Ultrafine powdery hydroxyapatite paste made with a non-aqueous casting sheet forming solvent is applied to the implant having the surface porous layer thus obtained, and after air-drying, at about 300 to 800 ° C for 1 minute to
Heat treatment was performed for 1 hour.

As a result, the pores of the implant were completely sealed with the apatite particles.

[Example 5] Al was directly sprayed on the surface of an alloy titanium implant material to form a coating film having a thickness of about 30 µm. This is 15% sulfuric acid and 2%
0-5 ° C current density in mixed electrolytic solution consisting of oxalic acid 3-4
Anodization was performed for 30 to 50 minutes under the condition of A / dm ² to form a hard alumite film. The obtained pore size was about 250Å.
Next, this film was etched at 50 ° C. in a 2M sulfuric acid solution to finally form a porous layer having a pore size of about 600Å.

Then, about 20 weight percent of apatite microcrystals adjusted to an average particle size of 200 to 300Å, about 80 weight percent of ethanol,
In addition, in an apatite suspension consisting of a trace amount of Alcl ₃
Electrodeposition was performed by electrophoresis for 1 to 5 minutes at a voltage of 0V.
After washing with water and drying, the result of heat treatment at 300-600 ℃,
The pores of the porous layer of the implant were filled with apatite particles.

Finally, as the final step of the above-mentioned series of treatment steps, the implant was immersed in tetrafluororesin, impregnated with Teflon in the coating, dried and then heat-treated at 350 to 400 ° C. As a result, the surface coating layer of the implant obtained was found to have excellent wear resistance and corrosion resistance as never before.

As described above, in order to investigate the adhesive strength to the bone and the biocompatibility of the composite implant according to the present invention shown in the examples, samples of the same size (cylindrical shape with a diameter of 5 mm and a length of 12 mm) were produced, and the thighs of rabbits and adult dogs were produced. It was embedded in bones and tibias, killed after 3 months, and punched out. The results are shown in Table 1 together with the comparative examples.

In the case of the present invention, from the measurement results of the punching strength listed in Table 1, the resistance to pulling out the sample from the living body is about 3 to 6 times as high as that without coating, and the adhesive strength is high and the adhesive strength is high. It was confirmed to have.

Regarding the method for coating the surface of the implant base with aluminum, other known methods other than this example, such as the hot dip aluminum plating method and the aluminum permeation plating method (calorizing method), may be used alone or according to the shape of the implant base. A combination of several methods can be selected. Also, filled in the pores of the alumina porous layer, or
In this example, as the bioactive substance to be coated, only hydroxyapatite was used, but of course, it is not limited to this, and various bioceramics such as TcP and various bioglasses such as calcium phosphate-based glass, etc. Any substance can be used alone or in combination, as long as it has good biocompatibility, and a part or all of its components are dissolved or absorbed in the living body to substitute for bone to form a strong bond.

On the other hand, the method for filling or coating the alumina porous layer with the bioactive substance is a known method, such as a dipping method, a coating method, or an electrophoresis method.

〔The invention's effect〕

As described above, the composite implant according to the present invention first forms a porous alumina layer having good adhesion on the surface of the substrate of the titanium-based implant, and further has a strong bond with bone such as hydroxyapatite in the pores. As an implant member filled with or coated with a bioactive substance, it has excellent corrosion resistance and wear resistance, has excellent biocompatibility, and is ideal for living organisms that also has sufficient hard tissue binding strength. An implant can be provided.

Continuation of the front page (56) Reference JP-A-60-185563 (JP, A) JP 58-50737 (JP, B2) JP 59-45384 (JP, B2)

Claims (2)

[Claims] 1. A porous alumina layer is adhered to the surface of an implant substrate made of titanium or a titanium alloy, and the pores of the porous alumina layer are filled with a bioactive substance such as hydroxyapatite and tricalcium phosphate. A composite implant characterized by the following. 2. A step of depositing an aluminum metal layer on the surface of an implant base made of titanium or a titanium alloy by means such as an ion plating method, a vapor deposition method and a sputtering method, and then anodizing the deposited aluminum metal layer. Method for producing a composite implant, comprising a step of converting the porous alumina layer into a porous alumina layer by a method, and then filling a bioactive substance such as hydroxyapatite or tricalcium phosphate into the pores of the alumina layer. .