JPH07323038A - Artificial dental root - Google Patents

Abstract

PURPOSE:To prevent the falling-off and extraction of an artificial dental root caused by infection and the breakage thereof and to solve a problem such as the loosening at the fixed part with a post. CONSTITUTION:A fixture 10 is mainly constituted of high strength ceramic such as alumina, sapphire or zirconia and the surface coming into contact with a bone thereof is constituted of ceramic imparting no injury to a living body. The average surface roughness of the outer surface of the upper end part 14 held by an appliance at the time of embedding and engaged with a post P of the fixture is set to 0.03mum or less and the post attaching hole 15 thereof is formed as a blind hole of which the inner wall surface has average surface roughness of 0.5-2.0mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial tooth root in which a lower fixture is embedded in a jawbone and a denture is crowned on the upper side.

[0002]

2. Description of the Related Art The history of artificial tooth root is relatively old, 1930.
The material has been developed, the shape, and the surgical technique have been improved since the 1980s.The artificial roots that have been used so far are histologically non-toxic and soft tissue in order to maintain stable and stable planting in the long term. , Pure titanium, which is harmless to both hard tissues,
Metallic materials such as titanium alloys, cobalt / chromium alloys, and ceramic materials such as alumina, zirconia, and HAP are used, and the shapes are screw type, hollow type, blade type, etc.
Furthermore, there are a single-planting method and a double-planting method as the operative method. The single-planting method includes, for example, the one-piece type shown in Japanese Examined Patent Publication No. 56-50975 and Japanese Patent Publication No. 31288/1992.
There is a two-piece type disclosed in Japanese Patent Laid-Open No. 96745 and Japanese Patent Laid-Open No. 5-293123.

Among the above-mentioned surgical methods, the one-piece type of the single implantation method is a method for osseointegration with the crown post exposed in the oral cavity. In this method, the fixture and the jawbone are separated. There was a risk of shaking and falling off because the occlusal teeth are occluded before they are sufficiently joined. Therefore, recently, a surgical method in which a post is attached after the joint between the fixture and the bone is sufficiently achieved, as in a one-time two-piece, two-time implant, is generally used.

[0004]

However, the above-mentioned conventional techniques have the following problems. That is, in the above-mentioned one-time method two-piece and two-time method implants, the shape and mechanism are complicated in order to prevent rotation of the post and to stably fix the post, and pure titanium from the viewpoint of strength, Metallic materials such as titanium alloys and cobalt / chromium alloys are used. However, these metallic materials are considerably inferior to the ceramic materials in affinity with soft tissues, and in some cases, artificial tooth roots have fallen off or have to be removed due to infection or the like.

There has also been a method of coating the surface of a metal with a ceramic material such as apatite. However, artificial tooth roots may be damaged by infection caused by destruction of the coating layer due to a difference in elastic modulus and thermal expansion coefficient between the metal and the ceramic. There was a problem that it could not be removed or removed.

Furthermore, in all of these artificial tooth roots,
In order to fix the post, there is a post fixing hole with an internal thread formed inward from the top surface of the fixture along the axial direction, and the fixture and post were detachably fixed, but the screw part is loose. In this case, there was a problem that the post had to be remade so that the threaded portion was not loosened.

[0007]

In order to solve the above-mentioned problems of the prior art, the present invention comprises a fixture mainly made of high-strength ceramic such as alumina, sapphire, zirconia, etc., and is held by an instrument during implantation and The outer surface of the upper end that engages with the post has an average surface roughness of 0.03.
The post attachment hole has an inner wall surface which is a blind hole having a rough surface with an average surface roughness of 0.5 to 2.0 μm.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an artificial tooth root 1 according to this embodiment, and the artificial tooth root 1 has a fixture 10 mainly composed of high-strength ceramic such as alumina, sapphire, or zirconia.

The fixture 10 has a self-tapping outer screw 11 formed on a lower side thereof, and a taper portion 12 for reinforcing a joint force with a compact bone, and an upper surface 1 above the outer screw 11.
3 has a regular hexagonal shape in a plan view, and is formed with an upper end portion 14 which is held by an implanting device during implantation of the fixture 10 and which engages with a post P on which a denture is crowned after implantation, and in the central portion thereof. The structure is such that the blind hole 15 for fixing the post is formed inward along the axial direction. The high-strength ceramic is a material having a bending strength of 5000 kgf / cm ² or more. In addition to the above, Si
C, Si ₃ N ₄ , TiN, TiC, TiO _2, NoC,
NoO ₂ , WC and the like can be mentioned. However, it is most preferable to use the above-mentioned alumina, sapphire, or zirconia from the viewpoint of affinity with living organisms. Further, the fixture 10 does not necessarily have to be integrated, and, for example, as shown in FIG.
The hollow cylindrical body 20 having a cylindrical shape for inserting the core material 10a may be configured as a separate body and attached to the glass by a known method. In any case, it is essential that the surface in contact with the bone be made of a material that is not harmful to the body.

The outer surface of the upper end portion 14 is a mirror surface having an average surface roughness of 0.03 μm or less, preferably 0.01 μm or less, which is polished after grinding, and the inner wall surface of the post mounting hole 15 is blasted or the like. The average surface roughness of 0.5 to 1.5 μm, preferably 1.0 to 1.5 μm.

FIG. 3 shows an artificial tooth root 1 according to another embodiment,
This artificial tooth root 1 has a structure in which the lower outer surface of the fixture 10 in the structure of the artificial tooth root 1 shown in FIG. 1 is a blind surface, and the outer portion 16 including the outer surface is a well-known method for the core of the fixture 10. It has a cylindrical shape for inserting the material 10a and has an average porosity of 100 to 200 μm and an average porosity of 30 to 50%.
It is preferable that a calcium phosphate-based material having an excellent affinity with bone is used for this portion in order to rapidly and strongly fuse with the bone.

FIG. 4 is an enlarged cross-sectional view of the portion A in FIG. 1, wherein the upper end corner 14 and the lower edge corner of the upper end portion 14 of the fixture 10 are rounded with respective radii of curvature r and R ≦ 1 mm. By adding it, it is possible to reliably suppress the occurrence of cracks at this portion.

Examples of calcium phosphate having excellent bone affinity include apatite, tricalcium phosphate, octacalcium phosphate, tetracalcium phosphate and the like.

In the artificial tooth root 1 constructed in this way, the surface of the fixture 10 embedded in the bone which contacts the bone is made of ceramics which is not harmful to the human body. There is no problem of removal, and even if the fixture 10 is mainly composed of high-strength ceramic, and the part including the surface in contact with the bone is separately formed and joined together, it is ceramics. Therefore, the elastic modulus and the coefficient of thermal expansion are close to each other, and the portion including the surface in contact with the bone is not broken or is not broken including the other portions.

Further, the outer surface of the upper end portion 14 which is formed on the upper surface 13 of the fixture 10 and which is held by an instrument at the time of embedding and which engages with the post is formed as a mirror surface having an average surface roughness of 0.03 μm or less. Since the torque strength is increased, micro cracks do not occur due to the torque due to the engagement with the device at the time of implantation, and the post mounting holes 15 are blind holes and are fixed to the posts P with cement. Since this is done, the structure is simplified, and it is free from problems such as loosening of the fixed part, and the inner wall surface of the post mounting hole 15 is a rough surface with an average surface roughness of 0.5 to 2.0 μm. As a result, the fixing force of the cement is increased and the cracks are prevented from being generated by the stress applied to the inner wall surface of the post mounting hole 15.

When the average surface roughness of the surface of the upper end portion 14 is larger than 0.03 μm, the torque strength becomes excessively small, and the torque at the time of embedding causes cracks in this portion, and the stress after fixing fixes the fixture. The char may be damaged.

If the average surface roughness of the inner wall surface of the post mounting hole 15 is smaller than 0.5 μm, the cement fixing force of the post by cement will be too small, and if it is larger than 2.0 μm, cracks will be caused by stress. It tends to occur.

Further, the upper end portion 14 of the fixture 10
When the radius of curvature r of each of the upper edge corner and the lower edge corner was R and R> 1 mm, there were cases in which the mechanical strength of this portion was lowered and cracks or chips were generated during the bone implantation. On the other hand, each radius of curvature r, R ≦ 0.4, more preferably r, R ≦
At 0.2, the mechanical strength of the upper end portion 14 including the torque strength was particularly large.

Experimental Example 1 The artificial tooth root 1 shown in FIG. 1 was made of sapphire, and the surface roughness of the outer surface of the upper end surface 14 was polished as shown in Table 1.

[0020]

[Table 1]

With respect to these artificial tooth roots, the torque (torsion) strength of the upper end surface 14 was measured using a known measuring instrument. The results are shown in Table 1.

Generally, the torque at the time of implanting is about 5.0 kgf / cm, but as shown in Table 1, when the surface roughness is more than 0.01 μm, the torque strength is too small and the fixture itself It was found that cracks could occur.

Experimental Example 2 In order to confirm the relationship between the surface roughness of the inner wall surface of the post fixing hole 15 of the artificial tooth root 1 and the bonding strength, bulk sapphire was prepared and its surface roughness was changed as shown in Table 2. The bonding strength was measured by the shearing method.

[0024]

[Table 2]

Resin-based vanavia was used as the cement, and a Pt-Pd alloy was used as the adherend. The results are shown in Table 2.

As shown in Table 2, when the surface roughness of bulk sapphire was less than 0.01, the bonding strength was too low. However, an example of crack generation was observed when the surface roughness of bulk sapphire was greater than 2.0.

Experimental Example 3 The artificial tooth root 1 shown in FIG. 1 was prepared from zirconia and the same experiment as in Experimental Example 1 was conducted. The results are shown in Table 3.
As shown in Table 3, the results of this experiment were almost the same as those of Experimental Example 1.

[0028]

[Table 3]

Experimental Example 4 Bulk zirconia was prepared and the same experiment as in Experimental Example 2 was conducted. The results are shown in Table 4. As shown in Table 4, the results of this experiment were almost the same as those in Experimental Example 2.

[0030]

[Table 4]

Experimental Example 5 The artificial tooth root 1 shown in FIG. 1 was prepared from zirconia, and the same experiment as in Experimental Example 1 was conducted. The results are shown in Table 5.
As shown in Table 5, the results of this experiment were almost the same as those of Experimental Example 1.

[0032]

[Table 5]

Experimental Example 4 Bulk zirconia was produced and the same experiment as in Experimental Example 2 was conducted. The results are shown in Table 6. As shown in Table 6, the results of this experiment were almost the same as those in Experimental Example 2.

[0034]

[Table 6]

[0035]

As described above, according to the present invention, since the surface of the fixture to be embedded in the bone, which is in contact with the bone, is made of a ceramic that is not harmful to human body, the artificial tooth root is dropped due to infection or the like. There is no problem of removal, and even if the fixture is composed mainly of high-strength ceramic, and the part including the surface that contacts the bone is formed separately and joined together, it is elastic because it is ceramics. There is no fracture of the portion including the surface which is in close contact with the bone and has a similar rate, or fracture including the other portions.

Further, the outer surface of the upper end portion, which is formed on the upper surface of the fixture and is held by an instrument at the time of implantation and engages with the post, is a mirror surface with an average surface roughness of 0.03 μm or less, and the torque strength of this portion is Since it has been made large, micro cracks etc. do not occur even due to torque due to engagement with the instrument at the time of implantation, and the post mounting hole is made a blind hole and the post is fixed with cement. Therefore, the structure is simple and free from problems such as loosening of the fixing part. Furthermore, the inner wall surface of the post mounting hole is made a rough surface with an average surface roughness of 0.5 to 2.0 μm, and it is fixed with cement. The force was increased and the stress applied to the inner wall surface of the post mounting hole did not cause cracks.

As described above, the present invention provides an artificial dental root that is extremely stable and safe in the living body.

[Brief description of drawings]

FIG. 1 is a perspective view of an artificial tooth root according to an embodiment of the present invention.

FIG. 2 is a perspective view of an artificial tooth root according to another embodiment of the present invention.

FIG. 3 is a perspective view of an artificial tooth root according to another embodiment of the present invention.

FIG. 4 is an enlarged sectional view of a portion A in FIG.

[Explanation of symbols]

 P post 1 artificial tooth root 10 fixture 11 outer screw 12 taper part 13 upper surface 14 upper end part 15 post fixing hole 16 outer part 17 porous 20 hollow cylinder

Claims (1)

[Claims] 1. An artificial tooth root for implanting a post on which a denture is crowned on the upper side of a lower fixture to be embedded in the jawbone, wherein the artificial tooth root is mainly made of alumina, sapphire, zirconia, or the like. Of high-strength ceramic, the outer surface of the upper end of which is held by an instrument during implantation and engages with the post has an average surface roughness of 0.03.
The post mounting hole is a blind hole with a mirror surface of less than μm, and a rough surface with an average surface roughness of 0.5 to 2.0 μm on the inner wall inward from the upper surface along the axial direction. An artificial tooth root characterized by being present.