JPH0761341B2 - Anchor member for anchoring to bone tissue - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a screw-shaped anchor member made of titanium for permanent anchoring to bone tissue. The anchoring members are particularly suitable for permanently anchoring dentures and bridges to the jawbone.

It has long been known to permanently anchor oral and extraoral artificial prostheses to bone tissue. In order to avoid the prosthesis from later relaxing, there is a period of adhesion, during which there is a direct contact, ie an exact fit, between the prosthesis and the bone tissue. Such a permanent exact adaptation that allows the load is called osseointegration. The potential for such long-term adaptation and function in clinical practice of load-bearing artificial anchors was first pointed out by Dr. Brandmark et al. They have shown that thread-shaped anchors made of pure titanium, or so-called fixtures, are osseointegrated if many preconditions are met. The principle of osseointegration developed by Dr. Blancmark et al. Has been clinically practiced for 20 years and has achieved good results, for example, it is described below.

Brandmark / Zab / Albreckson: Tissue Integrated Process (tissue integrated pr
Published by Quintessence Book, Inc. in 1985.

The principle of osseointegration is not only based on the use of implants made from pure titanium, but also with less trauma to install titanium fittings to set a specific adhesion period and load the fittings. To a specific surgical technique consisting of a first surgery to prevent direct action on the body and a second surgery to attach the artificial prosthesis part (bronch) to the fixture, ie a two-stage surgery involving an intermediate unloading period Based on.

In order to achieve a good adhesion of the fixture in bone tissue, negative biological reactions should be kept to a minimum, preferably only positive reactions.
The structure and chemical composition of the fixture are important for these reactions.

In Swedish patent 790235, it is described how an improved performance can be obtained with a particular surface structure of the titanium material of the fixture. The surface layer of the fixture consists of titanium dioxide with minute pits, the diameter of the surface pits being 10-1000 nm, preferably 10-300 nm. Swedish patent application 8505158-9 describes a titanium surface layer chemistry that is particularly advantageous for tissue reactions.

It is also important that the fixture facilitates safe surgery and has the proper shape to keep the surface clean. Swedish patent 332 486 describes a bolt-shaped fastening member with external threads. The threaded portion of the bolt is inserted into a hole drilled in the jawbone and has an internal thread for permanently implanting the dental fixation member. The bolt has a hole with an open front end and a radially oriented opening through a screw that enters the hole. The bolt has a conical front end. The opening in the front end portion of the bolt facilitates adhesion of the bolt to the jawbone by ingrowth of newly formed bone tissue through the opening to prevent the bolt from escaping.

As mentioned, the bolts are inserted into holes drilled in the jawbone. In order to meet the requirements of safe surgical techniques, the preparation of bone holes is done in several stages using several drills of increasing diameter and a series of screw taps. In order to safely prepare the fixation site, it is necessary to keep the temperature low, which requires a low drill speed and cooling by adequate irrigation with saline solution. The surface of the fitting must be very clean and must be carefully cleaned or use non-returnable equipment after each surgery.

In order to facilitate the surgical procedure and reduce the number of instruments required for bone tissue preparation, it is well known to provide fittings with cutting edges that produce a self-tapping action when attached to bone tissue. Therefore, in addition to forming bone ingrowth openings, it is necessary to further machine the end portion of the fixture to form such cutting edges. Examples of such self-tapping attachments can be found in EP-A-139052 and ED-A-3043336.

A complicated and expensive manufacturing method is required to form the opening and the cutting edge, and burrs are generated on the inner surface, which are difficult to remove.

It is an object of the present invention to provide an anchor member that meets the requirements of bone ingrowth and provides a self-tapping function.

Another object of the invention is to provide an anchoring member designed to reduce the risk of damaging the periosteum during insertion.

The titanium anchoring member of the present invention is an anchoring member for permanently anchoring to bone tissue, and is composed of a cylindrical body having an externally threaded surface with a frustoconical tapered front portion, and this cylindrical body is at least A cavity, the cavity having a portion of the outer threaded surface and the frustoconical taper adjacent thereto to allow newly formed bone tissue to grow into the cavity. The columnar body is formed so as to directly communicate with a part of the outer surface of the front portion, and the edge formed by the cavity and the externally threaded surface has the anchor member screwed into bone tissue. In a titanium anchoring member for permanent anchoring to bone tissue, which constitutes a cutting edge that provides a self-tapping action when the metal is filled, the entire volume of the cavity contains all bone tissue material scraped off by the self-tapping action. It is designed to Front of the front tapered frustoconical is titanium Ikaritome member for permanent Ikaritome the bone tissue, which is a non-porous.

The preferred embodiment of the present invention provides an anchor member for permanently anchoring a denture or bridge to the jawbone. In such an embodiment,
Two through-holes at right angles to each other through the body at right angles to the longitudinal axis of the body form a single cavity of approximately cruciform cross-section, ie a single cavity giving four openings communicating with the outside of the body. It is provided.

In another embodiment of the anchoring member, three separate cavities symmetrically distributed around the circumference of the body of the anchoring member are provided.

The anchoring member disclosed in the Swedish patent 332 486 has a cavity or well 11 through which loosened skeletal tissue material scraped off while the bolt is screwed into the bone hole can be collected in the cavity or well. However, the well cannot accommodate all of this shaved bone material. Furthermore, this vertical hole 11 not only communicates with the cylindrical outer surface of the bolt, but also opens downward, and the scraped bone material may fall to the bottom of the bone hole, disturbing the osseointegration at the base of the anchor member. There is. These drawbacks can be avoided by following the teachings of the present invention.

The above and other objects, features and advantages of the invention will be apparent from the following description and claims with reference to the accompanying drawings.

As shown in FIG. 1, the anchoring member, or so-called fixture, comprises a rigid, generally cylindrical body 1 having external threads 2 formed thereon. In the figure, only the front or base of the body is shown. The body is specifically designed to be inserted into a hole drilled in the jawbone to permanently anchor the denture or bridge. Thus the back or neck portion (not shown) of the body is attached by distance pieces, coupling elements or the like. However, these elements do not form part of the present invention and are therefore not described here. The anchoring members are made of commercially pure titanium, the surface structure and chemical composition of which are preferably the above mentioned Swedish patent specifications 790235-0 and 8505158.
According to -9.

The body 1 has a conical downwardly tapered (in use) front portion 3 to facilitate the insertion of a screw into a hole in bone tissue.
Have. The cone angle α is suitably about 20 °. The body 1 comprises one or more cavities 4 in direct communication with a portion of the externally threaded surface 2 and a portion of the outer surface of the front portion 3 adjacent thereto, which will be described in detail below in the illustrated embodiment. As such, a single cruciform cavity is provided.

The edge formed by the cavity 4 and the externally threaded surface forms a sharp cutting edge with a positive cutting angle, thus the screw still has a self-tapping action when anchored in bone tissue. The term "positive cutting angle" means that, when viewed in a cross section perpendicular to the central axis of the body 1, the direction from the radially outer edge 5 of the one side surface of the cavity 4 to the central axis of the body 1 is the upper side of the one side surface. It means an angle in a direction toward the central axis with respect to the one side surface that does not pass through the lower side of the one side surface (that is, the cavity 4 side). The volume of the cavity 4 is such that the bone tissue scraped away as the front part 3 of the fixture advances into the bone hole is completely contained within the cavity. The cavity is closed away from the four openings on the cylindrical outer surface of the body 1. That is, all tissue material that is scraped off is collected and stored in the cavity. The collected bone tissue material aids in the formation of newly formed bone tissue into the cavity and also prevents the fixture from escaping after insertion. The fixture has a flat, continuous front surface 6 with no openings.

The bone volume cavity is formed by two through-holes formed in the tubular surface of the body and perpendicular to the longitudinal axis of the body. The total volume of the cavity is defined by the number of holes and the cross-sectional area of the body. In the example shown, each hole has a longitudinal section with two straight edges parallel to the longitudinal axis of the body 1. However, it will be appreciated that the holes can be slightly inclined with respect to the longitudinal axis of the fixture body. However, no matter how they are formed, the common feature of the holes is that the total volume of the cavity formed is such that the bone tissue material to be shaved is contained and stored in the cavity over the length of the fixture. , And that the cavity and its cutting edges are formed by one or more holes in the tubular outer surface of the fixture.

Another embodiment of the self-tapping attachment according to the present invention is shown in FIGS. Similar to the fitting shown in FIGS. 1 and 2, this fitting also has a conical downwardly tapered (in use) front portion 7 and is suitable for fitting during surgery. It has a cone angle α of about 20 ° to facilitate sliding. The fitting has a continuous flat front surface to avoid unintended penetration of the periosteum. However, in this case, the fixture is three separate cavities or bone volumes (bo) that are symmetrically distributed around the circumference of the fixture but do not penetrate the fixture.
ne volumes) 8. These cavities are formed by external machining with slight burrs, i.e., more complicated and expensive and more efficient methods than the boring method, which is difficult to remove burrs on the inner surface.

In this case, the bone volume of the fitting cavity is adapted to the length of the fitting so that the bone tissue material to be chipped can be accommodated in the cavity. Therefore, each cavity is much deeper than in the case of conventional anchor members. In the embodiment shown in Figures 3 and 4, the depth of each bone volume cavity is about 50-80% of the radius of the fitting.
The longitudinal dimension of the cavity depends on the length of the fixture. As shown in FIG. 3, each cavity extends partially into the conical front portion 7 of the fixture, but not into the flat front surface.

FIG. 4 is a cross-sectional view taken above the conical taper of the body. This cross-section shows the form of a bone cavity 8 and a cutting tooth 9 with a cutting edge 10. Each bone cavity 8 is formed by a flat cutting surface 11 with a cutting edge 10 removed over a central portion to form a cutting edge, and a concave clearance surface 12, these surfaces 11, 12 being at right angles to each other. . The clearance surface 12 includes a lower curved portion 12a, a straight portion 12b, and an upper curved portion 12c (see FIG. 3). Each cutting tooth 9 comprises one cutting surface with a straight sharp cutting edge 10, a portion 13 of the outer tubular surface of the body of the fixture and a clearance surface 12.

Three separate bone cavities that give three cutting edges 10
As shown in FIGS. 4 and 5, the fixture is well balanced when it is screwed into bone tissue. However, the invention is not limited to providing three such bone cavities.

The above disclosure of the present invention is illustrative only, and details of the illustrated apparatus may be modified within the scope of the claims without departing from the spirit of the invention.

[Brief description of drawings]

1 and 2 are slightly schematic enlarged longitudinal and transverse cross-sectional views through the front end portion of an embodiment of an anchoring member of the present invention suitable for permanently anchoring a denture or bridge to a jawbone,
FIGS. 3 and 4 are slightly schematic enlarged corresponding sectional views through the front end portion of the second embodiment of the anchoring member of the present invention for permanently anchoring a denture or bridge to the jawbone. 1 ... Cylinder, 2 ... External screw, 4,8 ... Cavity, 9 ...
… Cutting tooth, 10 …… Cutting edge, 11 …… Cutting surface, 12 …… Gap surface.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Lars Journeus S-415 S.-415 16 Gotenbrüy, Bjornuv Ekterence, Gata 27 (72) Inventor Ciel Olov Hagberg S. 414-57 Gotenbruy, Sweden Kaberger Tan 14 (72) Inventor Rennalt Riyov S-414 57 Gotenbrüy, Seglargartan 27 Ar (72) Inventor Karl Arne Morenius S. S-431 43 Mijorndal, Toviringgartan 1 Say

Claims (9)

[Claims] Claim: What is claimed is: 1. An anchoring member for permanent anchoring to bone tissue, comprising a cylindrical body (1) having an externally threaded surface (2) with a frustoconical tapered front part (3, 7). The cylinder (1) comprises at least one cavity (4,8), said cavity being externally threaded to allow newly formed bone tissue to grow into this cavity. It is formed in the cylindrical body (1) so as to directly communicate with a part of the surface (2) and a part of the outer surface of the frustoconical tapered front part (3, 7) adjacent thereto. An edge (5, 10) formed by the cavity and the externally threaded surface constitutes a cutting edge that provides a self-tapping action when the anchor member is screwed into bone tissue. In a titanium anchoring member for permanent anchoring to a bone, the total volume of the cavity is a bone tissue material scraped away by the self-tapping action. A titanium anchor for permanent anchoring to bone tissue, characterized in that it is adapted to receive all, and the front face (6) of the frustoconical tapered front part (3, 7) is non-perforated. Stop member. 2. A first claim provided with a single cavity.
The titanium anchor member according to item. 3. The titanium anchoring member according to claim 2, wherein said single cavity is formed by at least one through hole of said body extending at right angles to the longitudinal axis of said body. 4. The two right-angled through holes pass through the body, and the longitudinal axes of the two holes are at right angles to each other, thereby forming a cavity having a cross-shaped cross section. The titanium anchor member according to item 3. 5. The titanium anchor member of claim 4 wherein each said through hole has a longitudinal section defined longitudinally by two parallel straight edges. 6. The titanium anchor member of claim 5 wherein the edge is substantially parallel to the longitudinal axis of the body. 7. A titanium anchoring member according to claim 1 provided with a plurality of separate cavities symmetrically distributed around the circumference of the body. 8. The titanium anchor according to claim 7, wherein each of the cavities is defined by a flat cutting surface having a positive cutting angle and a concave clearance surface perpendicular to the cutting surface. Element. 9. The titanium anchor member according to claim 7, wherein the three cavities are symmetrically distributed around the periphery of the body.