JP3261009B2 - Biological implant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

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

For example, in dental implants, diseases,
In order to replace a tooth that has fallen off due to a disease or accident with an artificial tooth, an implant is implanted and implanted in the jaw bone, and an artificial crown is mounted on the upper part of the implant. Such dental implants include cobalt chromium alloys, titanium alloys, iron nickel
Metal materials such as chromium alloys and ceramic materials such as single crystal sapphire and hydroxyapatite are used. However, such metal materials are often ionized by body fluids, blood, and the like, and often have an adverse effect on soft tissues of a living body. In recent years, ceramics that are stable in the living body have been used from this point, but since they transmit medical X-rays after surgery, they are converted to alumina 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 prior art has the following problems. That is, in the conventional alumina to which Y ₂ O ₃ or the like was added, the amount of added Y ₂ O ₃ was small, so that the X-ray opacity was low and the contrast was insufficient.

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

[0006] In addition, since the thermal conductivity was rather large,
For example, in the case of dental implants, there is a problem that irritation to nerve tissue is large when hot drinks and foods are put in the mouth, and because it is an opaque material, it is not possible to see through the affected part during surgery and it is not possible to secure sufficient visual field was there.

[0007]

SUMMARY OF THE INVENTION In order to solve the problems of the prior art as described above, the present invention provides a biological implant including a member made of ceramics mainly composed of yttria aluminum garnet crystals. Is what you do.

In the biological implant of the present invention, the average particle diameter of the ceramic mainly composed of yttria aluminum garnet crystals is 3 to 1 in order to maintain a balance between workability and strength and to improve slidability.
It was in the range of 00 μm.

[0009]

The bioimplant of the present invention is composed of mainly yttria aluminum garnet (hereinafter abbreviated as YAG) crystals as the desired member and contains Y ₂ O ₃ , so that X-ray non- High permeability allows clear contrast, low thermal conductivity, low stimulation of nerve tissue, transparency allows the affected part to be seen during surgery, good workability, and the production of irregular products There is an effect that there is.

Further, YAG ceramics have very good workability, for example, it is easy to machine a screw portion of a screw-type artificial tooth or to form a deformed shape, but 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 as small as 3 to 100 μm, the slidability is good.

The YAG ceramic may be either polycrystalline or single crystal.

[0012]

Embodiments of the present invention will be described below in detail. 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 the above-described YAG ceramics, and the joint 2 for rotatably connecting the first member and the second member is made of a 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 members can be post-processed into an appropriate shape in accordance with the shape of the medullary cavity, and the looseness with the bone can be prevented. It can be prevented beforehand. In addition, since the sliding property is good, the amount of wear at the hinge portion is small, and the adverse effect on the living body due to the wear powder can be prevented.

FIG. 2 shows a biological implant according to the present invention.
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 root S below a cylindrical post P, and is translucent. The appearance can be seen through the material, and it can be easily post-processed into a shape corresponding to the shape of the affected part of the patient, or because heat conductivity is small, stimulation such as heat is hardly transmitted to nerve tissue, for example, dental implants And the like, when hot drinks or foods are put into the mouth, the irritation of the teeth can be reduced.

EXPERIMENTAL EXAMPLE 1 42.9% of aluminum oxide and 57.1% of yttrium oxide were mixed at 1 % by weight, pulverized by adding water, and adjusted to an average particle size (D50) of 2.0 μm or less. Granulated with a spray dryer. After the granules were calcined at 1000 to 1400 ° C., they were pulverized again, a binder was added to make a slurry, and the slurry was granulated by a spray dryer. After the granules were formed by a mold press, they were fired in a vacuum furnace at 1600 ° C. to 1850 ° C. in vacuum to obtain YAG ceramics.

The finished YAG ceramic generally has a light-transmitting property. However, translucency is not always a requirement. In this molding, the molding is performed by a die press. However, a molding method such as a rubber press may be used, or a general ceramic molding method such as a casting 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. The bending strength is slightly inferior to that of alumina but is in a practically acceptable range. Processing is easier than alumina, and thermal conductivity is low, so that heat and other stimuli are not easily transmitted to nerve tissue. Can be reduced. The chemical resistance is almost the same level to sulfuric acid and nitric acid, and has an order of magnitude higher resistance to sodium hydroxide.

Further, it is possible to provide a light-transmitting property like single-crystal sapphire, and it is possible to see through the material the state of the affected part during the operation. Further, the number of voids in the open pores can be increased by changing the sintering conditions, and the bonding with the living tissue can be strengthened where the material strength is not so required.

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

[0022]

[Table 2]

For these dental implants, first, Vickers hardness and bending strength were measured. Table 2 shows the results.
Shown in

Further, the above-mentioned dental implant was subjected to thread cutting around the lower end of the cylinder with a diamond tool to produce a dental implant D as shown in FIG. 2. The easiness of the machining was visually observed and evaluated. Table 2 shows the results.

Further, this dental implant D was rotated about an axis, and was slid on a plate-shaped high-molecular polyethylene having a fixed upper end surface. This was continued for a long time, and the abrasion on the high-molecular polyethylene plate side was visually observed. Table 2 shows the results.

The final sliding test is not for confirming the characteristics required for the dental implant D.
For example, it was for estimating the sliding property at the hinge joint when the material of the present invention was used for the artificial finger joint F or 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 sliding properties are good, and among them, 5 μm to 30 μm.
In the case of μm, the results were particularly good considering the points such as strength. On the other hand, when the average particle size was smaller than 3 μm, workability was difficult, while when the average particle size was larger than 100 μm, strength and sliding property were not so good.

As described above, the average particle size of the YAG ceramics constituting the biological implant of the present invention is 3 μm to 3 μm.
It has been found that the thickness is desirably 100 μm, and particularly preferably 5 to 30 μm.

The present invention is not limited to the above-described embodiment, but may also be applied to a biological implant such as an artificial ankle joint, an artificial shoulder joint, a bone screw, an artificial skull, or a living / external opening member as a biological terminal. Can be.

[0030]

As described above, since the desired member of the biological implant of the present invention is made of YAG ceramics, it contains yttria and is non-transparent to X-rays, so that the site of the implant is clearly confirmed by X-ray inspection. YAG ceramics have low thermal conductivity and little irritation to the surrounding nerve tissue because they are YAG ceramics. By eliminating 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 the 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 biological implant according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st member 2 2nd member 3 Juint part F Artificial finger joint D Dental implant P Post part S Root part N Thread

Claims (2)

(57) [Claims] 1. A biological implant comprising a member made of ceramics mainly composed of yttria aluminum garnet crystals. 2. The ceramic according to claim 1, wherein said ceramic has an average particle size of 3 to 10.
The biological implant according to claim 1, wherein the thickness is within a range of 0 µm.