JPS6168054A - Artificial bone and tooth - 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] [Industrial Application Field] The present invention relates to artificial bone for restoring bone tissue lost due to tumor removal, trauma, etc., and for restoring teeth lost due to dental disease. This invention relates to an artificial tooth with a tooth root.

[Prior Art] Various metal alloys, organic substances, and the like have been used as hard tissue substitutes for living organisms, but they may deteriorate due to dissolution in the environment of living organisms or become toxic to living organisms, and may be accompanied by foreign body reactions. Currently, ceramic materials are being used that have excellent compatibility with living organisms and do not have the above-mentioned drawbacks. Among these ceramic materials, artificial bones and artificial teeth made of sintered bodies or single crystals of alumina, carbon, tricalcium phosphate, or hydroxyapatite, which have excellent biocompatibility, are being developed and are attracting attention.

Attempts have been made to use these sintered bodies or single crystals as artificial bones and artificial teeth, but the shape of the bone defect that requires actual treatment is not uniform and complex. It is difficult to process these sintered compacts or single crystals to fit the shape, and even if these sintered compacts or single crystals are filled, they are significantly harder than the surrounding bone tissue, so filling materials cannot be used. The stimulation causes bone resorption in the surrounding area, causing problems such as loosening, and it has not yet reached the level of practical use.

On the other hand, the sintered body is made into a porous body by a mechanical method or by adding combustible fiber to powder at the time of molding, molding, and sintering, and this is used as a filling material for bone defects and voids. Although this method is considered, it is insufficient in strength to be used as artificial bone and artificial teeth.
It is difficult to use it for these purposes.

[Object of the Invention] One object of the present invention is to provide an artificial bone and an artificial tooth that have excellent biocompatibility, do not cause foreign body reactions, and can be integrated with surrounding bone tissue in a particularly short period of time without intervening connective tissue. It's about doing.

Another object of the present invention is to provide an artificial bone and an artificial tooth that can particularly quickly repair and restore the structure and function of a bone tissue defect site.

Still another object of the present invention is to provide an artificial bone and an artificial tooth that can be ground to match the shape of the defective site on the spot during surgery, and that have strength and toughness comparable to that of living bones and teeth. There is a particular thing.

[Configuration of the invention] According to the invention, the calcium phosphate compound 10-90%
(volume ratio) and an organic polymer in an amount of 90 to 10% (volume ratio).

[Description of the invention] The present invention will be explained in more detail below.

The present inventors first focused on utilizing the osteogenic ability of calcium phosphate compounds because when a calcium phosphate compound is filled into bone defects and bone voids, new bone is generated in the areas. Calcium phosphate compounds that can be used in the present invention include tricalcium phosphate, hydroxyapatite, tetracalcium phosphate, oxyapatite,
Calcium pyrophosphate, fluoroapatite, compounds in which a portion of the hydroxyl groups of hydroxyapatite are replaced with fluorine ions, and mixtures thereof can be mentioned, but among these, the one that generates new bone at a faster rate is tricalcium phosphate. It is preferable to use one type or a mixture of two or more types selected from , hydroxyapatite, fluoroapatite, and tetracalcium phosphate. Among them, hydroxyapatite can be said to be the most preferable because it has the fastest rate of new bone formation. Among hydroxyapatites, temperatures of 500°C or higher, particularly preferably 7
Hydroxyapatite obtained by heat treatment at 00° C. or higher is particularly preferable because it generates new bone quickly.

The upper limit temperature of the heat treatment is not particularly limited, but since hydroxyapatite starts to decompose, it should be lower than the decomposition temperature. In addition, the calcium phosphate compound that can be used in the present invention may be artificially synthesized by a known manufacturing method such as a wet method, a dry method, or a hydrothermal method, or it may be a natural product obtained from bones, etc. May be used. Further, the calcium phosphate compound used in the present invention may be in the form of powder, granules, or porous material as long as it can be mixed with the monomer of the organic polymer.

The organic polymer used in the present invention is not particularly limited as long as it is non-toxic to living organisms and has an affinity with calcium phosphate compounds, but examples include carboxylic acid polymers such as polylactic acid and polyglycolic acid; polymethacrylate Carboxylic acid ester polymers such as methyl acid (hereinafter referred to as PMMA) and poly(trifluoroethyl methacrylate) (hereinafter referred to as PTFEMA); and olefin polymers such as polyethylene (hereinafter referred to as PE) and polypropylene; can be used. Among these, PMMA and PTFEMA are preferable in terms of strength and high affinity with calcium phosphate compounds, and PTFEM is particularly preferable.
A can be said to be the most preferable in that it has the highest affinity with calcium phosphate compounds.

The blending ratio of the calcium phosphate compound and the organic polymer is 10 to 90% (volume ratio) of the calcium phosphate compound, preferably 50 to 80% (volume ratio), and 90 to 1% of the organic polymer.
It should be 0% (by volume), preferably 80-50% (by volume).

If the blending ratio of the calcium phosphate compound is less than 10%, the biocompatibility of the artificial bone and artificial tooth will deteriorate, and the formation of new bone in the surrounding area will hardly be observed;
If it exceeds 90%, it becomes difficult to process artificial bones and artificial teeth, making it impossible to process them in accordance with the shape of the defective part. When the blending ratio is in the range of 50 to 80%, the amount of new bone produced around the artificial bone and artificial teeth is large, and the physical properties can be made close to those of bone, which is preferable.

In producing the artificial bones and teeth of the present invention, the calcium phosphate compound, in the case of powder or granules, is obtained by stirring and mixing with an organic polymer, and then polymerizing. In this case, in order to contain a large amount of calcium phosphate compound in the outer periphery of the artificial bone and artificial tooth, they can be manufactured by using a centrifugal casting method. On the other hand, when the calcium phosphate compound is a porous body, the porous body is placed in a container that can be depressurized, and an organic polymer monomer is added thereto and polymerized.

If you want to make the physical properties of artificial bone and artificial teeth more similar to those of bone, or if you want to make them stronger and tougher for safety when implanted in a living body, you can use a metal rod or plate in the center. You can also put it in. In this case, the metal is not particularly limited as long as it meets the above purpose, but it may be that the mixture of calcium phosphate compound and organic polymer cracks for some reason, so it has little or no toxicity to living organisms. It can be said that it is preferable to use stainless steel (316L), titanium, etc. When metal is placed in the center, it is preferable to do so so that the metal is not exposed on the outside. An adhesive is used for adhesion to metal, but the type of adhesive is not particularly limited as long as the desired adhesive strength can be obtained. The mixture of the calcium phosphate compound and organic polymer of the present invention has better adhesion to metals than other materials, and has high toughness, so it is difficult to crack due to bending and twisting.

The present invention will be specifically explained below using examples.

[Example 1 Tricalcium phosphate as a calcium phosphate compound and PM as an organic polymer in each powder of hydroxyapatite
MA, PTFEMA, and PE monomers were combined and mixed, and each of the six types of mixtures was subjected to double polymerization under pressure and heating to produce a mixture of a calcium phosphate compound and an organic polymer. In all cases, the proportion of the calcium phosphate compound was 50% (volume ratio).

Each of these mixtures was cut into a size of 5×5×5ffI11, filled into a defect (5×5×5 mm) created in the tibia of an adult dog, and observed over time from 1 week to 6 months after the surgery.

As a result, new bone formation was observed in direct contact around the mixture, but especially hydroxyapatite and P.
In the case of MMA, hydroxyapatite and PTFEMA produced the largest amount of new bone, followed by hydroxyapatite and PE.

Example 2] PTF'EMA and PMMA in hydroxyapatite powder
Two types of mixtures were prepared using the same method and composition as in Example 1. On the other hand, polymers were prepared using PTFEMA and PMMA alone, and cylinders of 6I1wIIφ were made from these, and defects of 6.5 diameter diameter were created in the tibia and femur of adult dogs.
It was filled in X7nn+L, and after 3 months, it was taken out and a punching test was conducted using 5 φ round rods.

As a result, P T F E M A , P M M
In the case of A alone, it was able to pass with a load of 10 kg/cJ or less, but PTFEMA, hydroxyapatite, and PMMA
In the case of a mixture of and hydroxyapatite, 50 kg/
- It was impossible to punch out even with a load of more than -.

[Example 3] Hydroxyapatite powder (149μ or less) and each PM
Using MA and PTFEMA, the mixing ratio was changed from 5% (volume ratio) to 90% (volume ratio) of hydroxyapatite in the same manner as in Example 1.
(50%, 70%, 90%) were filled into adult dogs in the same manner as in Example 1, and the condition was observed 3 months later. However, 95
Regarding %, filling was not performed because it could not be processed into the filling shape at the time of surgery.

As a result, when the hydroxyapatite content was 5%, almost no new bone was observed around the filled sample and a large number of foreign body giant cells were observed, but when the hydroxyapatite content was 10% or more, new bone was observed around the filled sample. The amount of foreign body giant cells was large in 50% or more, and no foreign body giant cells were observed. A strength test was conducted on these specimens in a dry state and after being left in saline for 9 weeks to approximate that of a living body. The results are shown in the table.

Bending test: JIS R1601 Compression test: JIS K 7208 [Example 4] The proportion of hydroxyapatite was 70% (volume ratio), hydroxyapatite powder and PTFEMA were placed in a square shape, 316L stainless steel 2IIIlφ was placed in the center, and the mixture was prepared in Example 1. It was produced in the same manner as.

When the mixture prepared above was subjected to bending and compression tests, it was 1800 kg/ad in bending and 1300 k in compression.
g/d, and a material having physical properties extremely similar to those of a living body's compact bone was obtained. Note that the bending and compression tests were conducted using the same test methods as in Example 3.

Claims (1)

[Claims] An artificial bone and an artificial tooth comprising 10 to 90% (volume ratio) of a calcium phosphate compound and 90 to 10% (volume ratio) of an organic polymer.