JPH06304184A - Intraosseous implant - Google Patents

Abstract

PURPOSE:To provide the intraosseous implant which suppresses the exposure of a body part 2 by bone absorption and eventually enables long-term use in a living body. CONSTITUTION:This intraosseous implant of a cylinder type consists of collar part 1 and a body part 2 thereunder and is provided with at least >= 1 points of dents (or grooves 3) in this collar part 1.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to improvements in endosseous implants used for dentistry and maxillofacial prostheses.

[0002]

2. Description of the Related Art At present, there are two types of intraosseous implants (hereinafter abbreviated as implants) in the field of dentistry: blade type and cylinder type. The blade-type implant has a plate-like shape in appearance and is used for repairing a free end defect in all parts of the jawbone, particularly from a premolar to a molar. A wide blade type is often used in this part because the lower alveolar canal is below the bone surface and a too long implant cannot be implanted. The perforation hole (prepared hole for implantation) is formed by moving in the mesio-distal direction while perforating with a drill having the same diameter as the width of the blade, and thus the shape is likely to collapse.

The cylinder type implant has a cylindrical shape and can be implanted in all parts of the jawbone. The shape of the fovea is circular, which allows more accurate holes to be formed for the implant diameter than the blade type. As for the operation style, the blade type is a push-in method, and the cylinder type is
There are two types: push-in method and screw-in method.

Generally, the state of the interface between the implant and the bone several months after the implant is implanted is one in which fibrous tissue is present between the implant and the bone,
There is a type in which the bone and the implant material are directly contacted or bonded. At present, the latter is the mainstream because it can be used stably for a longer period of time. The upper part of the implant is provided with a portion having a smooth surface, which is generally called “collar”. The main body, which is the lower part, maintains the implant in the bone and has a function of protecting the implant from shaking and falling off against various stresses generated in the oral cavity.

The body is generally in the form of being maintained in the bone by mechanical anchoring such as screws and surface irregularities. Furthermore, recently, attempts have been made to coat the surface of the main body with a bioactive material to improve the sustainability by chemical bonding with bone. Common methods of implanting an implant in bone are the "one-time procedure" and the "two-time procedure". In the one-time method, since the upper end of the implant penetrates the gingiva and is exposed in the oral cavity at the time of implantation, it is not necessary to incise the gingiva when attaching the superstructure to the upper end of the implant. In the double implant method, the implant is completely embedded in the bone at the time of implantation, and after several months, the gingiva is incised and a superstructure is attached to the upper end of the implant. Therefore, the length of the brim of the implant in the one-time method is as long as 5 to 10 mm, while it is 0.5 to 2 in the two-time method.
It is about mm, and there is a difference in the length of the brim.

[0006] Smoothing the surface of the brim has the effect of preventing the invasion of various bacteria from the oral cavity, but the brim does not contribute to the intraosseous maintenance of the implant unlike the main body. After implanting the implant, part or all of the brim is in a state of being embedded in the bone. Immediately after implantation in the case of the single implant method, and usually in the case of the double implant, after attaching the superstructure, the highest point (hereinafter called bone resorption point) of the part where the bone and the implant directly contact each other is Begins to fall. This phenomenon is generally called bone resorption and progresses to the boundary surface between the main body portion and the collar portion.

This bone resorption reduces the area of direct contact between the implant and the bone. When bone resorption is severe, the implant cannot withstand the stress of occlusion,
Bone resorption should be prevented as much as possible because it may fall off or break.

[0008]

As a method of preventing bone resorption, a method of increasing the bone contact ability in the collar portion and a cross-sectional shape of the bone in which the collar portion is provided with fine unevenness and is in direct contact therewith. A method of making unevenness is possible. In order to improve the bone contact ability in the collar portion, various processing may be performed on the collar portion, which may conversely promote bone resorption.
Sufficient consideration must be given to the processing of the brim. For example,
The bone resorption point is the interface between the implant and the three substances of bone and gingiva, and even a slight stimulus from the implant side causes an excessive response from the gingiva part, which greatly accelerates bone resorption. This is because the possibility is great. For example, if the ribs are sandblasted or the like to give fine irregularities, the direct contact force between the bone and the implant increases, but the fine irregularities also tend to adhere to plaques, and oral bacteria are It is more likely to exist, and easily leads to bone resorption through infection and inflammation.

As a method of enhancing the bone contact ability in the collar portion, it is conceivable to provide a bioactive ceramic layer on the collar portion. Bioactive ceramics are those that give an ionic stimulus to bone and are directly bound to the bone. Since bioactive ceramics may easily promote inflammation in soft tissues such as gingiva, the presence of bioactive ceramics at the bone resorption point is not preferable.

It is an object of the present invention to provide an endosseous implant which suppresses the exposure of the main body portion due to bone resorption and consequently enables long-term in-vivo use.

[0011]

Therefore, the present invention firstly provides a "cylinder-type intraosseous implant comprising a collar portion and a main body portion thereunder, in which at least one of the collar portions is provided.
An intraosseous implant (claim 1) characterized in that it is provided with at least one recess. In addition, the present invention is secondly "a cylinder-type intraosseous implant comprising a collar portion and a main body portion below the collar portion, wherein the collar portion is provided with at least one or more circumferential grooves. An internal implant (claim 2) ".

The third aspect of the present invention is that "the indentation has a size of 0.1 to 1 mm in width and 50 to 300 µm in depth, and the intraosseous implant according to claim 1 (claim 3). "I will provide a. In a fourth aspect, the present invention provides an "intraosseous implant (claim 4)", wherein the groove has a width of 0.1 to 1 mm and a depth of 50 to 300 µm. To do.

[0013]

[Function] When the macro protrusions are provided on the brim portion 1, it becomes a resistance at the time of implanting the implant, so that it is difficult to impart protrusions having a height of about 20 μm or more. Furthermore, since the resistance of the bone varies depending on the hardness of the bone, it is difficult to set an appropriate height.
On the other hand, even if the macro depression is provided in the collar portion 1, there is no influence when implanting the implant. Therefore, the shape of the depression can be freely selected.

The implant according to the first aspect of the present invention includes a collar portion 1
There is at least one recess on the bottom. Also,
In the implant of the second aspect of the present invention, the collar portion 1 is provided with at least one or more circumferential grooves 3. By providing the depression or groove 3, a two-step suppressing effect on bone resorption can be obtained. First, the first stage is the effect at the time when the bone resorption point reaches this recess or groove 3. That is, the bone contained in the depression or groove 3 is delayed in bone resorption by the volume. Furthermore, the effect of reducing the stress applied to the jawbone etc. was confirmed by the finite element method. For example, on the collar part 1 of a cylinder type implant, the width is 0.1 to 1 mm and the depth is 30 to 300 μ.
The following results were obtained by the finite element method when the m-shaped groove 3 was provided.

That is, the stress applied to the bone when a certain stress is applied to the implant in the model in which the bone resorption point is in the groove 3 portion and the model in which the bone resorption point is at the same height without providing the groove 3 Comparing the above, a stress reduction of 10 to 40% was calculated in the case where the groove 3 was provided, compared with the case where the groove 3 was not provided. Next, as a second step, there is an effect at the time when the bone resorption point reaches below the depression or the groove 3. Generally, due to bone resorption, an organic substance called fibrous tissue enters the portion where the direct bond between the bone and the implant is lost. In the case of a cylinder type implant, the running direction of fibrous tissue after bone resorption is parallel to the axial center direction. On the other hand, for example, in the periodontal ligament that supports natural teeth, fibrous tissue runs perpendicular to the teeth, and in the case of such fibrous tissue structure, the effect of suppressing bone resorption is large.

When fibrous tissue enters the depressions or grooves 3 according to the present invention, its running is disturbed, and the structure becomes similar to that of the periodontal ligament supporting the natural teeth. Therefore, the bone resorption rate decreases. In particular, when the depression or groove 3 is provided in the collar portion 1 of the implant in a ring shape, the fibrous tissue formed after the bone resorption runs in the ring groove. Therefore, it becomes perpendicular to the normal running direction of the fibrous tissue, and prevents the fibrous tissue from penetrating below the groove portion.

The size of the depressions or grooves 3 has a width of 0.1 to 1
mm, and the depth is preferably set in the range of 50 to 300 μm. If the depth of the depressions or grooves 3 exceeds 300 μm or the width thereof exceeds 1 mm, the mechanical strength is remarkably reduced, and the implant easily breaks. In addition, the width of the depression or groove 3 becomes smaller than 0.1 mm, and the depth is
If it is less than 50 μm, bacterial infection is likely to occur, leading to bone resorption.

The depression or groove 3 may have any cross-sectional shape such as an arc, a V-shape, a trapezoid, a square, a rectangle, or a polygon, but it is difficult for the plaque to adhere and the cleaning property is improved. In addition, it is preferable that they have no corners and are rounded. The shape of the main body 2 may be any shape, for example, a screw type (those provided with screws), fine irregularities (for example, sprayed film) or projections (for example, ridges) provided on the surface. Etc. can be used.

The material of the collar portion 1 and the main body portion 2 is, for example,
Ti, a Ti alloy, a metal such as a Co—Cr system, bioinert ceramics such as aluminum oxide and zirconium oxide, a bioactive material (ceramics, glass, crystallized glass, etc.) are preferable. For crystallized glass, for example,
There are ABC and AW. Further, it is preferable to provide a bioactive layer 2 ′ made of a bioactive material on the surface of the main body 2 made of metal or bioinert ceramics. Because of the osteoconductive effect of the bioactive material, the initial fixation with the bone can be made faster than when it is not provided. That is, the bone is entangled with the material components of the main body and the bond with the bone is accelerated.

As a pretreatment for providing the bioactive layer 2 ', the main body portion 2 is subjected to, for example, a blast treatment to clean and roughen the surface, and after the blast treatment, a chemical treatment such as acid etching or anodic oxidation is further performed to obtain a surface. Is more preferably roughened. This is because the contact area with the bioactive layer 2'is increased and the adhesion strength is increased. The bioactive layer 2'is preferably provided on the surface of the main body 2 as thinly as possible,
For example, it is preferable that the surface of the main body portion 2 is scattered in a spot shape. That is, it is preferable that the exposed portion of the main body portion 2 be larger than the portion where the bioactive layer 2 ′ is provided. With this configuration, the exposed portion of the main body 2 is easily entangled with the bone and is easily coupled.

The bioactive material forming the bioactive layer 2'includes, for example, hydroxyapatite, tricalcium phosphate, bioactive glass or glass ceramics (see, for example, J. Biomed. Mater. Res. Sy.
mp. No. 2 (Part1) pp. 111-141
(1971), JP-A-50-21015, JP-A-51.
-106114, JP-A-53-145394, JP-A-54-17, JP-A-54-135496, JP-A-57-3739, JP-A-58-118746, etc.), Apatite-based sintered bodies described in JP-A-62-052163 are preferable.

Examples of the method for providing the bioactive layer 2'include vapor phase methods such as vapor deposition, CVD, sputtering, and ion plating, solid phase methods such as thermal spraying and sintering, and liquid phase methods such as anodic oxidation. preferable. Further, in order to improve the adhesion strength between the surface of the main body 2 and the bioactive layer 2 ′, an intermediate layer may be provided between the surface of the main body 2 and the bioactive layer 2 ′, or the main body 2
A layer in which the composition of the bioactive material and the intermediate layer material is continuously changed can be provided between the surface and the bioactive layer 2 '.

The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

[0024]

[Example] Diameter 3.5 mm, length 10 mm, brim length 2 m
Cylinder type double implant (implant A) with a width of 0.5 m at the collar 1 of the implant A.
An implant B (FIG. 1) having two circumferential grooves 3 of m and a depth of 150 μm was prepared.

Three implants, one implant A and two implants B (B1, B2), were implanted in the jawbone of the dog, and each implant was fitted with a superstructure. Six months later, the implant A and the implant B1 were excised, and a few years later, the implant B2 was excised to prepare a pathological tissue specimen, and the contact state between each implant and the bone was observed. As a result, in implant A, the bone resorption point was the interface between the collar portion 1 and the main body portion 2. In implant B1, bone resorption was stopped at the upper groove. In implant B2,
Bone resorption had stopped just below the lower groove. Also, fibrous tissue was running along the groove in the upper groove.

[0026]

INDUSTRIAL APPLICABILITY As described above, the endosseous implant of the present invention suppresses the exposure of the main body 2 due to bone resorption, and as a result, it can be used in vivo for a long period of time.

[Brief description of drawings]

FIG. 1 is a side view of an implant B according to an embodiment.

[Explanation of symbols]

1 ... Collar part of intraosseous implant 2 ... Main part of intraosseous implant 2 '... Bioactive layer provided on main part surface of intraosseous implant 3 ... Groove and above

Claims (4)

[Claims] 1. An intraosseous implant of a cylinder type comprising a collar portion and a main body portion below the collar portion, wherein the collar portion is provided with at least one recess. 2. A cylinder type intraosseous implant comprising a collar portion and a main body portion below the collar portion, wherein the collar portion is provided with at least one or more circumferential grooves. 3. The size of the recess is 0.1 to 1 m in width.
m, depth 50-300 μm.
The described intraosseous implant. 4. The intraosseous implant according to claim 2, wherein the groove has a width of 0.1 to 1 mm and a depth of 50 to 300 μm.