JPH06304185A - 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 a collar part 1 and a body part 2 thereunder and is provided with at least >=1 points of grooves 3 in a circumferential direction in this collar part 1 and is provided with ruggedness or a vioactive layer 2' on the surface of this body pant 2.

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 part with a smooth surface, generally called “collar”, and the main part, which is the part below it, keeps the implant in the bone and resists various stresses generated in the oral cavity. It has the function of protecting the implant from shaking and falling. 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.

Common methods of implanting an implant in bone are the "single-step method" and the "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 the whole of the brim is in the bone. Immediately after implantation in the case of the one-time implant, after attaching the superstructure normally in the case of the two-time implant, the highest point (hereinafter referred to as 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. As a method of preventing bone resorption, a method of increasing the bone contact ability in the collar portion, a method of giving macro irregularities to the collar portion, and making the cross-sectional shape of the bone that is in direct contact therewith irregularities are considered.

[0008] When the collar portion is variously processed in order to enhance the bone contact ability at the collar portion, conversely, bone resorption may be promoted. Therefore, sufficient consideration must be given to the processing of the collar portion. . 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 there is a high possibility that For example, when sand blasting or the like is applied to the brim, if the fine irregularities are applied, the direct contact force between the bone and the implant increases, but the irregularities also tend to adhere to plaques and easily cause oral bacteria. It is easy to get 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.

Therefore, a macro unevenness is given to the collar portion,
As a method of making the cross-sectional shape of the bone that is in direct contact therewith uneven, a method of giving the ribs large unevenness to the extent that infection or inflammation does not easily occur is considered. If you provide a macro projection on the collar, it will be a resistance when implanting, so
It is difficult to provide protrusions with 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 a macro depression is provided in the brim,
There is no effect when implanting. Therefore, the shape of the depression can be freely selected. By the way, the main body portion is generally in the form of being maintained in the bone by mechanical anchoring such as a screw or surface unevenness. 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.

[0012]

When a metal or bioactive material having an uneven surface is used for the main body, there is an advantage that direct connection between the bone and the main body can be obtained in a short period of time. However, if these surfaces are exposed from the inside of the bone due to, for example, bone resorption, there is a disadvantage that the bone resorption rate increases as compared with the case where the main body has a smooth surface.

However, in the conventional implant using a metal or bioactive material having an uneven surface for the main body,
No special shape is given to the brim to prevent bone resorption. Therefore, improper implantation or postoperative management,
For various other reasons, bone resorption may progress and the main body may be exposed. When the body is exposed, the bone resorption rate is accelerated. In addition, it often causes severe inflammation to cause a funnel-shaped remarkable absorption in the tooth neck.

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.

[0015]

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.
There is provided an intraosseous implant (claim 1), characterized in that it is provided with at least one circumferential groove, and the surface of the main body is provided with irregularities or a bioactive layer.

A second aspect of the present invention is that "the size of the groove has a width of 0.1 to 1 mm and a depth of 50 to 300 µm (claim 2). "I will provide a.

[0017]

In the implant of the present invention, the collar portion 1 is provided with at least one circumferential groove 3. By providing the 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 groove 3. That is, the effect that the bone contained in the groove 3 is delayed with respect to the bone resorption by the volume is obtained. Furthermore, the effect of reducing the stress applied to the jawbone etc. was confirmed by the finite element method. For example,
Cylinder type implant has a width of 0.1 ~ on the collar part 1
The following results were obtained by the finite element method when the ring-shaped groove 3 having a depth of 1 mm and a depth of 30 to 300 μm 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 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 groove 3 according to the present invention, its running is disturbed, and the structure becomes similar to that of the fibrous tissue in the periodontal ligament that supports the natural tooth. Therefore, the bone resorption rate decreases. In particular, when the groove 3 is provided in the collar portion 1 of the implant in a ring shape, the fibrous tissue formed after the bone resorption travels in the ring groove. for that reason,
It becomes perpendicular to the normal running direction of fibrous tissue and prevents fibrous tissue from penetrating below the groove.

The size of the groove 3 is preferably set such that the width is 0.1 to 1 mm and the depth is 50 to 300 μm. Groove 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 groove 3 is smaller than 0.1 mm or the depth is smaller than 50 μm, bacterial infection is likely to occur, resulting in bone resorption.

The cross-sectional shape of the groove 3 is, for example, a circular arc, V-shape,
Although any shape such as a trapezoid, a square, a rectangle, and a polygon is possible, it is preferable that the shape is rounded without corners in order to prevent plaque from adhering and to improve cleanability.
The shape of the main body 2 can be any shape, for example,
Those provided with screws (screw type, see FIG. 2), those provided with fine irregularities (for example, sprayed film) and projections (for example, ridges) on the surface can be used.

The combination of the material and the surface roughness of the main body 2 according to the present invention includes a smooth surface made of metal, an uneven surface made of metal (maximum surface roughness of several μm to several tens μm), and a smooth surface made of bioinert ceramic. There are six types: bio-inert ceramics for uneven surfaces, bioactive materials (ceramics, glass, crystallized glass, etc.) for smooth surfaces, and bioactive materials for uneven surfaces. here,
The smooth surface and the uneven surface have maximum surface roughnesses of 1 μm or less and several μm to several tens of μm, respectively. Further, it is preferable that the uneven surface on the surface of the main body is provided by, for example, thermal spraying, anodic oxidation, sandblasting, or the like.

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, ceramics such as aluminum oxide and zirconium oxide, and the bioactive material are preferable. 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 2 and the bond with the bone is accelerated.

As a pretreatment for providing the bioactive layer 2 ', the main body portion 2 is, for example, cleaned and roughened by a blasting treatment, and after the blasting treatment, a chemical treatment such as acid etching or anodic oxidation is further performed. 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 (eg, 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-54-135494, JP-A-57-3739, JP-A-58-118746, etc.), Apatite-based sintered bodies described in JP-A-62-052163 are preferable.

As the method for providing the bioactive layer 2 ', for example, vapor phase method such as vapor deposition, CVD, sputtering, ion plating, solid phase method such as thermal spraying and sintering, and liquid phase method such as anodization. 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 '.

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

[0028]

[Example] Diameter 3.5 mm, length 10 mm, brim length 2 m
Cylinder type double implant (implant A) in which m is sprayed on the main body (material Ti) 2.
And a width of 0.5 mm and a depth of 150 on the collar portion 1 of the implant A.
an implant B provided with two μm circumferential grooves 3;
On the surface of the main body portion 2 of the implant B, Japanese Patent Laid-Open No. 62-052.
An implant C (FIG. 1) having a bioactive layer 2 ′ provided by thermal spraying of an apatite-based sintered body (an example of a bioactive material) described in Japanese Patent No. 163 and a main body 2 having the same brim portion 1 as the implant B. The implant D (FIG. 2), which is a polished screw, and the implant E in which Ti was sprayed on the main body 2 of the implant D were implanted in the jawbone of a dog.

Regarding the implants A, B, C and E,
The superstructure was installed 3 months after implantation. Implant D
At 3 months after implantation, the bone and implant were not sufficiently connected, so the superstructure was attached 6 months after implantation. The oral environment after the superstructure was attached was kept clean, and special care was taken to prevent plaque from adhering to the superstructure of the implant.

After a certain period of time, the implant was removed and a pathological tissue sample was prepared to observe the contact state between the implant and bone. As a result, in the implant A, the bone resorption point was the interface between the collar portion 1 and the main body portion 2. In implants B, C, D and E, the bone resorption point was the upper groove. Furthermore, after a certain period of time, the implant was removed to prepare a pathological tissue specimen, and the contact state between the implant and the bone was observed. As a result, in implant A,
There was a bone resorption point between the interface between the main body 2 and the boundary and a portion 1 mm from the top of the main body 2. Implants B, C,
In D and E, bone resorption was stopped at the lower groove portion or immediately below it. Fibrous tissue was running along the groove.

Further, implants A, B, C, D and E were similarly implanted, and after the superstructure was attached, a dental suture was wrapped around the superstructure so that plaque was easily attached. Several years after the implantation, the implant was removed to prepare a histopathological specimen, and the contact state between the implant and the bone was observed. As a result, the implant A mainly has a boundary portion with the main body 2 and 1 mm from the top of the main body 2.
Although there was a bone resorption point between the part and the part of (1), in some artificial tooth roots, large bone resorption (up to about 5 mm from the top of the main body part 2) was observed together with remarkable inflammation of the cervical part. Implant B,
In C, D, and E, bone resorption was stopped at or below the lower groove. Fibrous tissue was running along the groove.

[0032]

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.

FIG. 2 is a side view of an implant D according to an embodiment.

[Explanation of symbols]

1 ... Collar part of intraosseous implant 2 ... Main part of intraosseous implant 2 '... Bioactive layer provided on the surface of main part of intraosseous implant 3 ... Above groove

Claims (2)

[Claims] 1. A cylinder-type intraosseous implant comprising a collar portion and a body portion below the collar portion, wherein at least one or more circumferential grooves are provided in the collar portion, and the surface of the body portion has irregularities or a living body. An intraosseous implant having an active layer. 2. The intraosseous implant according to claim 1, wherein the groove has a width of 0.1 to 1 mm and a depth of 50 to 300 μm.