JPH06327702A - Intraosseous implant - Google Patents

Abstract

PURPOSE:To suppress the exposure of a body part by asteoclasis and eventually to enable the in-vivo use of the intrabony implant over a long period of time. CONSTITUTION:This intrabony implant of a cylinder type consists of a collar part 1 and a body part 2 thereunder and is equiped with dents 3 of 0.1 to 1mm width and 50 to 300mum depth at least at >=1 positions of the collar part 1.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to improvements in endosseous implants 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.

In general, the state of the interface between the implant and the bone several months after the implantation of the implant is such that the fibrous tissue is present between the implant and the bone and the bone and the implant material are in direct contact with each other. Alternatively, there is a type to be combined. 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”. Smoothing the surface of the brim has an effect of preventing 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.

The main body portion, which is a portion below the brim portion, has a function of maintaining the implant in the bone and protecting the implant from shaking and falling off against various stresses generated in the oral cavity.
The body is generally configured to be retained 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.

[0006] Common methods for implanting an implant in bone include a "single-step method" and a "double-step method". 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 one-time implant is 5 to 10 m.
While it is as long as m, it is about 0.5 to 2 mm in the double method, and there is a difference in the length of the brim.

After implanting the implant, a 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.

[0009]

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 for improving the bone contact ability of the collar portion, it is possible to provide a layer of bioactive ceramics 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.

When a metal or bioactive material having an uneven surface is used for the main body, there is an advantage that a direct bond between the bone and the main body can be obtained in a short period of time. When exposed from the inside of the bone, there is a problem that the bone resorption rate becomes higher than that of the main body having a smooth surface. However, in the conventional implants having an uneven surface and using a metal or a bioactive material for the main body portion, no measures are taken on the collar portion to suppress bone resorption. Therefore, due to poor management after implant implantation or surgery, or other reasons, bone resorption progresses and the main body part is exposed, causing severe inflammation, and there is often a funnel-shaped resorption in the tooth neck. There was a problem.

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

[0013]

Therefore, the present invention firstly provides a "cylinder-type intraosseous implant comprising a collar portion and a body portion below the collar portion, and at least one of the collar portions.
There is provided an intraosseous implant (claim 1) characterized in that recesses having a width of 0.1 to 1 mm and a depth of 50 to 300 μm are provided at more than one place.

Further, the present invention secondly "intraosseous implant (claim 2), characterized in that fine irregularities and / or bioactive layers are provided on the surface of the main body". I will provide a.

[0015]

[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.

In the implant of the present invention, a recess 3 having a depth of 50 to 300 μm is formed at least at one or more places on the collar portion 1.
Is provided. By providing the depression 3, a two-step suppressing effect on bone resorption can be obtained. First, the first step is the effect at the time when the bone resorption point reaches this recess 3.
That is, the effect that the bone contained in the depression 3 is delayed with respect to the bone resorption by the volume thereof is obtained.

Next, as a second step, there is an effect at the time when the bone resorption point reaches below the depression 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, the fibrous tissue runs perpendicularly to the teeth, and in the case of such fibrous tissue structure, the effect of suppressing bone resorption is large.

When a fibrous tissue enters the depression 3 according to the present invention, its running is disturbed, and the structure becomes similar to that of the periodontal ligament supporting the natural tooth. Therefore, the bone resorption rate decreases. The size of the depression 3 has a width of 0.1 to 1
mm, and the depth is set in the range of 50 to 300 μm. Hollow 3
If the depth exceeds 300 μm or the width exceeds 1 mm, the mechanical strength is remarkably reduced, and the implant is likely to break. If the width of the recess 3 is smaller than 0.1 mm or the depth is smaller than 50 μm, bacterial infection is likely to occur, leading to bone resorption.

The shape of the main body 2 can be any shape, for example, a screw type (having a screw) or a protrusion (for example, a ridge) provided on the surface can be used. . As the material of the brim portion 1 and the main body portion 2, for example, Ti, T
i alloys, metals such as Co-Cr, bioinert ceramics such as aluminum oxide and zirconium oxide, bioactive materials (ceramics, glass, crystallized glass, etc.)
Are preferred. Examples of crystallized glass include ABC and AW.

Fine irregularities (for example,
It is preferable to provide a sprayed film) and / or a bioactive layer. This is because the provision of the fine irregularities improves the retaining force by mechanical anchoring. Further, when the bioactive layer made of the bioactive material is provided, the initial fixation with the bone can be made faster than when it is not provided due to the osteoconductive effect of the bioactive material. 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, the main body 2 is cleaned and roughened by, for example, a blast treatment, and after the blast treatment, a chemical treatment such as acid etching or anodic oxidation is further performed to further improve the surface. It is preferable to roughen the surface. This is because the contact area with the bioactive layer increases and the adhesion strength increases. When the bioactive layer is thinly provided on the surface of the main body 2, for example, even when the bioactive layer is scattered on the surface of the main body 2, the bone and the main body are bonded at a sufficient speed.

As the bioactive material forming the bioactive layer, for example, hydroxyapatite, tricalcium phosphate,
Bioactive glass or glass-ceramics (see, eg, J. Biomed. Mater. Res. Symp.
No. 2 (Part1) pp. 111-141 (197)
1), JP-A-50-21015, JP-A-51-106
114, JP-A-53-145394, JP-A-54-
17, JP-A-54-135496, JP-A-57-3
No. 739, JP-A-58-118746 and the like), and apatite-based sintered bodies described in JP-A-62-052163 are preferable.

As a method for providing the bioactive layer, for example, vapor phase methods such as vapor deposition, CVD, sputtering, ion plating, solid phase methods such as thermal spraying and sintering, and liquid phase methods such as anodization are preferable. Further, in order to improve the adhesive strength between the surface of the main body 2 and the bioactive layer, an intermediate layer is provided between the surface of the main body 2 and the bioactive layer, or between the surface of the main body 2 and the bioactive layer. It is also possible to provide a layer in which the composition of the bioactive material and the intermediate layer material is continuously changed.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

[0025]

[Example] Diameter 3.5 mm, length 10 mm, brim length 2 m
m, the surface of the main body 2 was sprayed with Ti (formation of fine irregularities), a cylinder type implant for double implantation (implant A), the collar 1 of the implant A had a width of 0.5 m
m, an implant B (FIG. 1) provided with a recess 3 which is a part of a spherical surface having a depth of 150 μm, and the apatite-based sintered body described in JP-A-62-052163 on the surface of the main body 2 of the implant B. An implant C, which has been sprayed with, and an implant D, which has the same collar portion 1 as the implant B, the main body 2 is a polished screw, and an implant E, which is obtained by spraying Ti on the main body 2 of the implant D, are prepared, Implanted in the jawbone of a dog.

Regarding the implants A, B, C and E,
Three months after implantation, each implant was fitted with a superstructure. As for implant D, the bones and the implants were not sufficiently connected 3 months after the implantation, and therefore, 6 months after the implantation, the upper structure was attached to the implant. The oral environment after the superstructure was attached was kept clean, and care was taken to prevent plaque from adhering to the superstructure of the implant.

Then, after a lapse of a certain period of time, each implant was extracted to prepare a pathological tissue specimen, and the contact state between each implant and the bone was observed. As a result, in implant A, there was a bone resorption point at the interface between collar portion 1 and main body portion 2. In implants B, C, D, and E, bone resorption was stopped at the recess 3.

Further, after a lapse of a certain period of time, each implant was extracted to prepare a pathological tissue specimen, and the contact state between each implant and the bone was observed. As a result, in the implant A, there was a bone resorption point between the interface between the collar portion 1 and the body portion 2 and the portion 1 mm from the top of the body portion 2. In implants B, C, D, and E, bone resorption was stopped at the depression 3 or immediately below it.

[0029]

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 (a) and a sectional view (b) of an implant B according to an embodiment.

[Explanation of symbols]

 1 ... Collar part of intraosseous implant 2 ... Body part of intraosseous implant 3 ... Recess

Claims (2)

[Claims] 1. A cylinder type intraosseous implant comprising a collar portion and a main body portion below the collar portion, wherein the collar portion has a width of 0.1 to 1 mm and a depth of 50 at least at one or more locations.
An intraosseous implant characterized by having a recess of ~ 300 μm. 2. The surface of the main body has fine irregularities and / or
The intraosseous implant according to claim 1, further comprising a bioactive layer.