JP2000060958A - Manufacture of implant material for organism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the mechanical strength, quicken the binding to the bone and make keepable the stability over a long period of time by dipping a base material made of titanium metal in an alkali solution, sintering the same, and dipping the same in a calcium hydroxide solution. SOLUTION: For example, a pure titanium plate is used as a base material, dipped in about 5 mol/l of NaOH water solution and then washed with pure water. The material is dried to form a coat composed of a titania phase and a sodium titanate gel phase on the surface of the base material. The obtained material is sintered at about 60 deg.C for about one hour to alterate a part of the sodium titanate gel phase to a sodium titanate phase. Subsequenty, the material is dipped in a calcium hydroxide water solution with the concentration of 0.1-20M mol/l, and then washed with water and dried to obtain an implant material for an organism. Thus, apatite can be formed in a short time, and the speed of connection to the bone can be increased.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a bioimplant material.

[0002]

2. Description of the Related Art Conventionally, various bioimplant materials have been proposed as substitute materials for bone. For example, high-strength materials such as stainless alloys and titanium-based metals such as titanium and titanium alloys, and bioactive materials such as apatite sintered bodies, bioactive glass, and bioactive crystallized glass are known.

High-strength materials such as stainless alloys and titanium-based metals have high mechanical strength, but require a long period of time to bond with bone. Further, bioactive materials such as apatite sintered body, bioactive glass, and bioactive crystallized glass are bound to bone in a short period of time, but their strength is insufficient and their application sites are limited. Therefore, an implant material in which a coating made of a bioactive material is formed on the surface of a high-strength material by plasma spraying or baking has also been proposed.However, even in this material, the base material and the coating are formed during long-term implantation in the living body. Peeling may occur at the interface of.

Therefore, the present applicant has filed Japanese Patent Application No. 8-357040.
Proposes an implant material in which a coating film made of a titania phase or an alkali titanate phase is formed on the surface of a base material made of a titanium-based metal, and calcium ions are contained in the coating film.

[0005]

In the above-mentioned materials, the coating is formed integrally with the base material and has bioactivity, so that the coating does not peel off even after bonding with natural bone. However, this material requires a long postoperative rest period due to its slow bond speed with natural bone.

[0006] An object of the present invention is to provide a method for producing a bioimplant material having high mechanical strength, binding to bone in a short period of time, and being stable in vivo for a long period of time.

[0007]

The method for producing a bioimplant material of the present invention is characterized in that a base material made of a titanium-based metal is immersed in an alkaline solution, baked, and then immersed in a calcium hydroxide solution. And

[0008]

The method for producing the bioimplant material of the present invention will be described in detail.

First, a titanium-based metal is formed into a desired shape to prepare a base material. Examples of the titanium-based metal include pure titanium, Na, Mg, P, Nb, Zr, Al, Sn, Pt,
A titanium alloy added with Ta, V, etc. can be used.

Next, the substrate is immersed in an alkaline solution.
A thin film of titania is usually present on the surface of the titanium-based metal, and when they are brought into contact with an alkaline solution, these react with each other to form an alkaline titanate gel. Titania gel may also be formed. In this way, a coating having a titania phase or a titania gel phase and an alkali titanate gel phase is integrally formed on the surface of the base material. As the alkaline solution, an aqueous solution of sodium hydroxide, potassium hydroxide or the like is used. Conditions such as the concentration, temperature, and immersion time of the alkaline solution may be determined according to the degree of formation of the film on the material surface, but the concentration is 2 to 10 mol / l, and the temperature of the solution is 25.
Appropriate dipping time is 12 to 48 hours at ˜90 ° C.

Subsequently, the substrate is fired to transform a part or the whole of the alkali titanate gel into a stable alkali titanate to enhance the stability of the coating. The firing condition is 200
It is desirable that the transition temperature of the substrate is within 4 hours.

After that, the substrate is immersed in a calcium hydroxide solution. At this time, if the treatment is performed in an atmosphere in which carbon dioxide is present, such as the atmosphere, the carbon dioxide in the atmosphere reacts with the calcium hydroxide solution to produce calcium carbonate, which adheres to the coating surface of the substrate. Further, the calcium hydroxide solution reacts with the film of the base material to produce calcium titanate on the surface of the film.

An aqueous solution of calcium hydroxide can be used as the calcium hydroxide solution. The concentration of the calcium hydroxide solution is preferably 0.1 to 20 Mmol / l, particularly preferably 5 to 20 Mmol / l. Concentration is 0.1Mmo
If it is lower than 1 / l, it becomes difficult to produce calcium carbonate or calcium titanate, and if it is higher than 20 Mmol / l, the amount of calcium carbonate is too much produced, and film peeling or cracking occurs and it becomes difficult to obtain a strong bond with bone. The liquid temperature of the calcium hydroxide solution is 50 to 150 ° C., especially 1
It is preferably in the range of 00 to 140 ° C. Liquid temperature is 5
If the temperature is lower than 0 ° C, it becomes difficult to generate calcium carbonate or calcium titanate, and if the temperature exceeds 150 ° C, the amount of calcium carbonate is excessively increased, and film peeling or cracking occurs, which makes it difficult to obtain a strong bond with bone. The treatment time may be appropriately adjusted depending on the concentration of the solution and the temperature of the solution, but it is suitable to perform the treatment within a range of 10 minutes to 3 days.

The implant material produced by the above method has a coating having a titania phase and an alkali titanate phase formed on the surface of a base material made of titanium metal, and calcium carbonate crystals or calcium titanate phase is formed on the coating surface. Exists. When this material comes into contact with body fluids, alkali ions (and calcium ions) in the alkaline titanate phase and alkaline titanate gel phase (and calcium titanate on the coating surface) in the coating are exchanged with hydronium ions in the body fluid to form the titania gel phase. And becomes the nucleus of apatite formation. The ion exchange also raises the pH of the body fluid near the implant material, creating an environment in which apatite easily precipitates. Further, when calcium carbonate crystals are present on the film, they serve as seeds for adsorbing calcium ions in the body fluid, and subsequently adsorbing phosphate ions in order to maintain electrical neutrality. In this way, bone-like apatite is rapidly formed on the surface of the coating, and it is possible to early bond with bone through this layer.

[0015]

EXAMPLES The present invention will be described below based on examples.

Table 1 shows examples of the present invention (Sample Nos. 1 to 1).
3) and a comparative example (sample No. 4) are shown.

[0017]

[Table 1]

Each sample was prepared as follows.

First, a pure titanium plate having a size of 10 × 10 × 1 mm was prepared as a base material. Then, the substrate is 5 mol /
It was immersed in 5 ml of an aqueous NaOH solution (60 ° C.) for 24 hours, washed with pure water, and dried to form a film composed of a titania phase and a sodium titanate gel phase on the surface of the base material. Then, the base material was baked at 600 ° C. for 1 hour to change a part of the sodium titanate gel phase to the sodium titanate phase. After that, the sample was obtained by immersing in 5 ml of an aqueous solution of calcium hydroxide or an aqueous solution of calcium chloride under the conditions shown in the table, washing with pure water and drying. When the temperature was lower than 100 ° C, the treatment was carried out in a constant temperature bath, and when the temperature was 100 ° C or higher, the treatment was carried out in an autoclave.

The obtained sample was dipped in a simulated body fluid prepared to have the same ion concentration as that of the body fluid, the period required for forming an apatite layer was investigated, and the binding rate with bone was evaluated.
The results are shown in Table 1.

As is apparent from the table, the comparative example N
o. The sample of No. 4 required 120 hours for the formation of apatite, whereas the sample of No. In samples 1 to 3, apatite was formed in a short time of 12 to 24 hours.

[0022]

EFFECTS OF THE INVENTION According to the production method of the present invention, it is possible to easily produce a bioimplant material which has high mechanical strength, can be bound to bone in a short period of time, and is stable in the body for a long period of time. Is.

Continued front page    F-term (reference) 4C081 AB02 CF032 CF22 CF23                       CF26 CG02 CG03 DC03 DC05                       DC14 EA05

Claims (4)

[Claims] 1. A method for producing a bioimplant material, which comprises immersing a base material made of a titanium-based metal in an alkaline solution, firing it, and then immersing it in a calcium hydroxide solution. 2. The method for producing a bioimplant material according to claim 1, wherein an aqueous calcium hydroxide solution is used as the calcium hydroxide solution. 3. The method for producing a bioimplant material according to claim 1, wherein a calcium hydroxide solution having a liquid temperature of 50 to 150 ° C. is used. 4. A calcium hydroxide solution having a concentration of 0.1 to 20 Mmol / l is used.
For producing a bioimplant material of the above.