JPH08322926A - Bioimplant - Google Patents

Abstract

PURPOSE: To reduce a stimulus on nerve tissue and enable penetration during operation by forming a bioimplant by ceramics mainly composed of crystals of yttria, aluminium and garnet so that as X-ray impermeability is large, imaging is clear. CONSTITUTION: For example, a first member 1 and a second member 2 of a hinge-type artificial interphalangeal joint F as a bioimplant are formed by yttria-aluminium-garnet(YAG) ceramics. A joint 2 for connecting the first member and the second member to each other in such a manner as to freely rotate is formed by synthetic resin such as polyethylene or the like. In this arrangement, the first and second members 1, 2 formed by YAG ceramics have good workability and the members can be after-worked into a suitable form according to the form of a bone marrow cavity. Accordingly, looseness to the bone can be prevented. Further, the sliding ability is good, and the abrasion loss of the hinge part is small so that it is possible to prevent a bad influence upon a living body due to abrasion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biomedical implant such as a dental implant made of ceramics or an orthopedic intraosseous implant.

[0002]

2. Description of the Related Art Conventionally, there has been used a treatment method of implanting an implant made of an artificial material in a hard tissue of a human body.

For example, in dental implants, illness,
In order to replace a tooth that has fallen due to a disease, accident, or the like with an artificial tooth, an implant is implanted in the jawbone and an artificial crown is attached to the upper part of the implant. Such dental implants include cobalt / chromium alloys, titanium alloys, iron / nickel /
Metallic materials such as chromium alloys, ceramic materials such as single crystal sapphire and hydroxyapatite are used. However, such metal materials are often ionized by body fluids or blood, which adversely affects the soft tissues of the living body. In recent years, ceramics that are stable in the living body have been used in many cases from this point of view, but since they transmit X-rays for medical use after surgery, alumina is used as shown in JP-B-51-39654. Attempts have been made to add X-ray opacity by adding additives such as Y ₂ O ₃ .

[0004]

However, the above-mentioned prior art has the following problems. That is, in the conventional alumina containing Y ₂ O ₃ or the like, the amount of Y ₂ O ₃ added was small, so that the X-ray opacity was low and the contrast was insufficient.

Further, all of the conventional ceramic implant materials are difficult-to-cut materials, and there is a problem that it is not easy to form a screw and to finely adjust the size and shape by post-processing.

Besides, since the thermal conductivity was rather large,
For example, in the case of dental implants, when hot drinks or foods are put into the mouth, there is a problem that irritation to nerve tissue is large, and since it is an opaque material, it is not possible to see through the affected area during surgery and it is not possible to secure a sufficient visual field was there.

[0007]

In order to solve the above-mentioned problems of the prior art, the present invention provides a bioimplant comprising a member composed of ceramics mainly composed of yttria-aluminum-garnet crystals. To do.

Further, in the bioimplant of the present invention, in order to maintain the balance between workability and strength and further improve slidability, the average particle size of the ceramics mainly composed of yttria-aluminum-garnet crystals is 3 to 1
The range was 00 μm.

[0009]

[Action] biological implant of the present invention, the desired member yttria aluminum garnet (hereinafter, referred to as YAG) With the arrangements because mainly of crystals, X-ray because the content of Y ₂ O ₃ Because of its high transparency, the contrast is clear, the thermal conductivity is low, the nerve tissue is not stimulated, and if it has transparency, the affected area can be seen through during surgery. There is an action.

Further, YAG ceramics have very good workability, and for example, it is easy to process the screw part of a screw type artificial tooth root and to perform atypical processing. However, by setting the particle diameter to a small range of 3 to 100 μm, The strength is also kept relatively high. If the particle size is reduced to the range of 3 to 100 μm, the slidability is good.

The YAG ceramics may be either polycrystal or single crystal.

[0012]

EXAMPLES Examples of the present invention will be described in detail below. FIG. 1 shows a hinge type artificial finger joint F as a biological implant of the present invention.

The first member 1 and the second member 2 are both made of YAG ceramics as described above, and the joint 2 for rotatably connecting the first member and the second member is made of synthetic resin such as polyethylene.

In this artificial finger joint F, since the first member 1 and the second member 2 made of YAG ceramics have good workability, the member can be post-processed into an appropriate shape according to the shape of the medullary cavity to loosen the bone. It can be prevented. In addition, since the slidability is also good, the amount of wear of the hinge portion is small, and the adverse effect of wear particles on the living body can be prevented.

FIG. 2 shows a bioimplant of the present invention, which is Y
Shows a dental implant D made of AG ceramics,
This dental implant D is one in which a thread groove N is easily formed by post-processing using a diamond tool in a tooth root portion S below a columnar post portion P, and it is transparent, so It is possible to see the situation through the material, and it is easy to post-process it into a shape according to the shape of the affected part of the patient, or because the thermal conductivity is small, it is difficult for heat and other stimuli to be transmitted to nerve tissue. Etc., it has the feature that when a hot drink or food is put in the mouth, the irritation such as bleeding in the teeth can be reduced.

Experimental Example 1 4 % by weight of aluminum oxide and 57.1% of yttrium oxide were mixed in a weight percentage of 1 and water was added to pulverize the mixture so that the average particle size (D50) was 2.0 μm or less, and then a binder was added and stirred. Granulated with a spray dryer. The granules were calcined at 1000 to 1400 ° C., then pulverized again, and a binder was added to form a slurry, which was granulated by a spray dryer. The granulated body was molded by a die press and then fired in a vacuum furnace at 1600 ° C to 1850 ° C in a vacuum to obtain YAG ceramics.

The finished YAG ceramics are generally transparent. However, translucency is not always a requirement. Further, in the main molding, the molding is performed by a die press, but a molding method such as a rubber press may be used, or a general ceramics molding method such as a cast molding method may be used. Table 1 shows the measured properties of the prepared sample.

[0018]

[Table 1]

This table compares YAG with 99.9% alumina, and although the bending strength is slightly inferior to that of alumina, it is in a practically unproblematic region and the Vickers hardness is low. It is easier to process than alumina, and its thermal conductivity is small, so it is difficult for heat and other stimuli to be transmitted to nerve tissue.For example, when dental foods such as dental implants are eaten with frozen products or hot foods, they cause irritation to the teeth. Can be reduced. Also, the chemical resistance is almost the same level for sulfuric acid and nitric acid, and has a resistance that is different by one digit for soda resistant soda.

Further, it is possible to impart a translucency like single crystal sapphire, and the state of the affected area during the operation can be seen through the material. Further, the voids in the open pores can be increased by changing the sintering conditions, and the bond with the biological tissue can be strengthened where the material strength is not so required.

Experimental Example 2 In the method for producing the YAG ceramics of Example 1, the firing temperature and the keeping time were changed as shown in Table 2, and Table 2
A columnar dental implant made of ceramics having an average particle size as shown in was prepared.

[0022]

[Table 2]

Vickers hardness and bending strength of these dental implants were first measured. The results are shown in Table 2.
Shown in

The dental implant was threaded around the lower end of the cylinder with a diamond tool to prepare a dental implant D as shown in FIG. 2. The easiness of processing was visually observed and evaluated. The results are shown in Table 2.

Further, this dental implant D was rotated about its axis and slid on a plate-shaped high-molecular polyethylene whose upper end surface was fixed. This was continued for a long time, and the state of wear on the side of the high-molecular polyethylene plate was visually observed. The results are shown in Table 2.

Although the last slidability experiment is not for confirming the characteristics required for the dental implant D,
For example, the purpose was to estimate what the slidability of the hinge joint part would be when the material of the present invention was used for the artificial finger joint F and the like.

As is clear from Table 2, when the average particle size of the YAG ceramics is 3 μm to 100 μm, the strength, workability and slidability are all good, of which 5 μm to 30 μm.
In the case of μm, the result was particularly good considering the strength etc. comprehensively. On the other hand, if the average particle size is smaller than 3 μm, the workability is poor, while if the average particle size is larger than 100 μm, the strength and slidability are not so good.

From the above, the average particle size of the YAG ceramics constituting the biological implant of the present invention is 3 μm
It has been found that 100 [mu] m is desirable, and in particular, 5-30 [mu] m is more desirable.

The present invention is not limited to the above-mentioned embodiments, and may also be used as a bioimplant such as an artificial ankle joint, an artificial shoulder joint, a bone screw, an artificial skull bone, and an in-vivo / intracorporeal opening member as a biometric terminal. You can

[0030]

As described above, since the desired member of the bioimplant of the present invention is made of YAG ceramics, it contains yttria and is impermeable to X-rays, so the site of the implant can be clearly confirmed by X-ray inspection. Yes, because it is YAG ceramics, its thermal conductivity is low, and its stimulation to the surrounding nerve tissue is small. Without the opacity, which is a drawback of general ceramics, it is possible to see through the affected area during surgery. It has many excellent effects such as easy production of products and excellent chemical resistance.

[Brief description of drawings]

FIG. 1 is a side view of an artificial finger joint as a biological implant according to an embodiment of the present invention.

FIG. 2 is a side view of a dental implant as a living body implant according to an embodiment of the present invention.

[Explanation of symbols]

 1 1st member 2 2nd member 3 Joint part F Artificial finger joint D Dental implant P Post part S Root part N Thread groove

Claims (2)

[Claims] 1. A bioimplant comprising a member made of ceramics mainly composed of yttria aluminum garnet crystals. 2. The average particle size of the ceramic is 3 to 10
The bioimplant according to claim 1, which is in the range of 0 μm.