JP2880755B2 - Artificial root - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of an artificial root made of a composite material of a metal base and a ceramic material.

"Prior art and its problems" As this kind of artificial dental root, there is conventionally known an artificial dental root having a ceramic material, for example, a hydroxyapatite layer formed on the outer surface of a bottomed dental root base made of titanium. The hydroxyapatite layer is formed into a bottomed cylindrical shape that adheres to the outside of the root base material by sintering in addition to thermal spraying or coating, and both are joined via an adhesive. The root base material mainly functions as a strength member, and hydroxyapatite functions to increase biocompatibility with the jaw bone. Forming hydroxyapatite in a cylindrical shape with a bottom has been considered to be indispensable for bringing only hydroxyapatite having excellent biocompatibility into contact with the jaw bone.

However, in this conventional artificial tooth root, it is difficult to form and process a hydroxyapatite having a bottomed cylindrical shape, and stress concentration is apt to occur at the bottom during the processing. There is a problem that the yield of products is deteriorated by the cracks generated due to the stress concentration. Furthermore, when the conventional artificial root weight is applied with a torque greater than the adhesive force of the adhesive between the root substrate and the hydroxyapatite, the root substrate may rotate with respect to the bottomed cylindrical hydroxyapatite. there were.

[Object of the Invention] An object of the present invention is to obtain a composite artificial dental root having higher strength based on the above awareness of the problem with an artificial dental root made of a composite material of a metal substrate and a ceramic material.

"Summary of the Invention" The present invention is based on the above analysis result that the conventional problem is caused by the fact that the ceramic material has a cylindrical shape with a bottom. The metal substrate is formed in a shape, and the metal substrate is composed of a pair of divided substrates which are divided in the axial direction of the cylindrical ceramic material and are connected to each other with the cylindrical ceramic material interposed therebetween. It is characterized in that a detent means is provided between the divided body.

According to this configuration, since the relatively brittle ceramic material has a simple cylindrical shape with both ends open,
There is no stress concentration during sintering and processing, and there is no risk of cracking due to this. As for the metal substrate, the divided metal substrate located below the cylindrical ceramic material comes into contact with the jaw bone. However, if an appropriate material is selected as the metal substrate, no problem occurs in terms of biocompatibility. Rather, due to the biocompatibility of the tubular apatite, which has no problem in strength, a more favorable state of bone adhesion can be maintained, and as a whole, more favorable results can be obtained than the conventional product. As the metal substrate used for such a purpose, titanium or stainless steel is preferable. As the ceramic material, a calcium phosphate ceramic excellent in biocompatibility, and in particular, apatite such as hydroxyapatite and fluorapatite is preferable.

"Examples of the Invention" The present invention will be described below with reference to illustrated examples. FIG. 1,
FIG. 2 shows a first embodiment of the present invention. The apatite cylinder 11 is formed in a cylindrical shape having the same diameter, and both ends thereof are open. Metal substrate 20 made of titanium
Is composed of a divided core body 21 and a divided bottom body 22.

The divided core body 21 has a cylindrical portion 21a fitted on the inner periphery of the apatite cylinder 11, and an outer flange 21b integrally provided at one end of the cylindrical portion 21a, and an inner surface of the cylindrical portion 21a. Has a female screw 21c
Are formed.

The split bottom 22 has a flat portion 22b at the upper end thereof, and a male screw 22a screwed to the female screw 21c of the split core 21 protrudes from the center of the shaft.

The axial length of the split bottom 22 is preferably equal to or less than the axial length of the apatite cylinder 11 in consideration of biocompatibility and bone adhesion. The outer surface shape of the divided bottom body 22 can be appropriately changed.

The apatite cylinder 11 has a detent groove 11a formed in a part of its circumferential direction parallel to the axis, and a projection 21d that fits into the detent groove 11a is formed in the cylindrical portion 21a of the divided core body 21. Have been. Of course, the relationship between the groove and the projection may be reversed.

Therefore, this artificial tooth is aligned with the protrusion 21d and the rotation preventing groove 11a, and the apatite cylinder 1 is attached to the cylindrical portion 21a of the divided core body 21.
Then, the male screw 22a of the divided bottom body 22 is screwed to the female screw 21c of the divided core body 21 to assemble. Then split core 21
The apatite cylinder 11 is sandwiched and fixed between the outer flange 21b and the upper surface flat portion 22b of the divided bottom body 22. Note that instead of the female screw 21c and the male screw 22a, the divided core 21
And the split bottom body 22 can be combined.

Between the apatite cylinder 11 and the cylindrical portion 21a of the split core body 21,
It is preferable to interpose an adhesive, particularly an adhesive having elasticity. However, if the rotation is prevented by the rotation preventing groove 11a and the projection 21d, this adhesive can be omitted. In addition, the rotation stopper can be provided between the divided bottom body 22 and the apatite cylinder 11. FIG. 3 shows an example of this, in which a projection 22c is provided on an upper surface flat portion 22b of a divided bottom body 22, and an apatite cylinder is provided.
A groove 11b into which the projection 22c fits is provided at an end of the groove 11.
When the groove 11b is provided, the male screw 22a is not formed, but is fixed by an adhesive.

After the present artificial tooth root is embedded in the jawbone, the abutment portion of the denture is inserted and fixed to the female screw 21c of the split core body 22. The female screw 21c can be used for fixing the denture.
That is, a male screw to be screwed into the female screw 21c may be formed on the abutment portion of the denture. Of course, in order to ensure the directionality of the denture, a key groove can be provided on the inner surface of the cylindrical portion 21a, or conversely, the key portion and the female screw 21c can be provided and only the adhesive can be used for bonding.

In addition, on the outer periphery of the divided bottom body 22, a detent is provided for the jawbone,
Alternatively, a groove 22d (which may be a protrusion or a hole) for penetrating the new bone can be formed, or a male screw 22e for screwing can be formed.

4 to 8 each show another embodiment of the present invention. In these embodiments, only a longitudinal sectional view is shown, but the same detent means as in the first embodiment,
The groove 22d, the external thread 22e, and the like of the divided bottom body 22 can be similarly provided.

FIG. 4 shows an embodiment in which the outer diameter of the apatite cylinder 11A is tapered so that the diameter increases toward the top. According to this embodiment,
Even if the diameter of the embedding hole formed in the jaw bone is relatively rough, a sufficient contact pressure can be generated between the tapered apatite cylinder 11A and the (drilled hole) of the jaw bone. For this reason, it can be expected that the progression of resorption of the jaw bone is delayed, and the osseous adhesion is more favorably performed.

FIG. 5 shows an example in which the split core 21A
In this embodiment, a male screw 21e is formed, and a female screw 22 embedded with the male screw 21e is formed in the divided bottom body 22A instead of the male screw 22a.

FIG. 6 is a modified version of FIG.
The diameter of the cylindrical portion 21a and the external thread 21e is reduced toward the bottom, and the thickness of the apatite cylinder 11B is increased accordingly. According to this, the strength of the relatively brittle apatite cylinder 11B can be increased.

FIG. 7 shows that the split bottom body 22B is
A cylindrical portion 22g that fits into the apatite cylinder 11 is formed, a male screw 22h is formed at the upper end thereof, and between the flange ring 23 screwed to the male screw 22h and the upper surface flat portion 22b of the divided bottom body 22. The apatite cylinder 11 is sandwiched and supported.

As described above, the shape of the metal divided base that is divided in the axial direction of the apatite cylinder 11 can be variously changed.

[Effects of the Invention] As described above, in the present invention, in an artificial tooth root made of a composite material of a metal base and a ceramic material, the ceramic material is formed in a cylindrical shape with both ends open, so that the molding and processing are easy. , And hardly generate residual stress, and hardly crack. Since this cylindrical ceramic material is sandwiched and supported by the divided base, an artificial dental root having high strength as a whole can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the artificial tooth root of the present invention, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. It is an exploded perspective view of a part. 4 to 7 are longitudinal sectional views showing other embodiments of the present invention. 11, 11A, 11B ... apatite cylinder, 11a, 11b ... detent groove, 20 ... metal base, 21, 21A, 21B ... split core body (split base), 21a ... cylindrical part, 21b ... Outer flange, 21c…
... female screw, 21d ... protrusion, 21e ... male screw, 22, 22A, 22B
... Division bottom body (division base), 22a ... Male screw, 22b ... Top plane part, 22c ... Protrusion, 22d ... Groove, 22e ... Male screw, 2
2f female screw, 22g cylindrical part, 22h male screw, 23
Flange ring (divided base).

Continuation of front page (72) Inventor Masafumi Nakamura 2-36-9 Maeno-cho, Itabashi-ku, Tokyo Asahi Optical Industry Co., Ltd. (56) References JP-A-57-176905 (JP, A) (58) Investigation Field (Int.Cl. ⁶ , DB name) A61C 8/00

Claims (1)

(57) [Claims] 1. An artificial tooth root made of a composite material of a metal base and a ceramic material, wherein the ceramic material is formed in a cylindrical shape having both open ends, and the metal base is formed in the axial direction of the cylindrical ceramic material. It is composed of a pair of divided bases which are divided and connected to each other with the cylindrical ceramic material interposed therebetween, wherein a rotation preventing means is provided between the cylindrical ceramic material and the divided body of the metal base. Artificial roots.