GB2311470A - Fastening artificial means to a body bone part - Google Patents

Description

Fastening Artificial Means to a Body Bone Part This invention relates to a device and to a method for fastening artificial means, such as a dental piece, to at least one human or animal bone or bony part. Hereinafter the term "body bone part" will be used to refer to such a human or animal bone or bony part.

As is known, the loss of teeth or parts of teeth and their substitution by artificial dental pieces currently poses a number of problems, especially in the case of oneoff pieces or small numbers of pieces which do not warrant the construction of a complete denture.

Systems for implanting dental pieces have been proposed which are based on the insertion of pegs, forming parts of the dental pieces, into natural or artificial sockets made for this purpose in the jaws. Such known systems involve forming screw-threaded sockets in the jawbones and screwing the screw-threaded pegs or tenons of the artificial dental pieces into these sockets. In such cases, implantation involves inserting a peg into the natural or artificial socket, with the consequent problems associated with the risk of rejection, inflammation phenomena and the like, such as infections due to necrosis of the bony cells, produced by screw-threading the cavities.

It is an aim of the present invention to provide a method and device for fastening artificial means, e.g. a dental piece or a connector for joining bone pieces, which eliminates the abovementioned drawbacks and provides a practical and efficient system for immobilizing bone pieces in general and for implanting artificial teeth, individually or as a group.

According to one aspect of the present invention a method of fastening artificial means to at least one body bone part comprises adhering at least one insert having a screw-threaded socket within at least one recess of said body bone part(s) and screwing a part or parts of the artificial means into the screw-threaded socket(s).

The or each insert is not in direct contact with the walls of the recess formed in the, or the associated, body bone part, e.g. a jaw or jawbone, but is surrounded on its external surfaces within the recess by an adhesive product which is applied initially in the fluid or pasty state and is characterized by its rapid hardening, high strength and complete suitability vis-a-vis the bony and fleshy tissues forming the bone part. Such an adhesive product is known ce se, is well proven and is distinguished by its ability to be accepted without rejection by the areas of the body to which it is applied and with which it is possible for it to physically merge.

According to other aspects of the present invention there are provided a fastening device and a fastening system as claimed in ensuing claims 1 and 8, respectively.

The invention provides for an insert having a screwthreaded socket to be positioned in a desired position within a bone part recess or cavity and for a threaded peg of a dental piece or other artificial piece which it is desired to implant, to be screwed into the screw-threaded socket of the insert. This operation can be carried out with little or no problems once the insert has been fastened and sterilized in the place envisaged.

Embodiments of the invention will now be described, by way of non-limiting example only, with particular reference to the accompanying drawings, in which: Figures 1, 2 and 3 are a partly sectioned side view, part end view from above and part end view from below, respectively, of an insert for fastening a dental piece; Figure 4 shows a side view of an auxiliary assembly element for use with the insert of Figures 1 to 3; Figure 5 shows a side view of a dental piece for use with the insert of Figures 1-3; Figure 6 shows the insert of Figures 1 to 3 placed in a body cavity with the dental piece of Figure 4 received in the insert; and Figure 7 shows the fastening of two bone parts using an external element.

A fastening device in accordance with the invention basically comprises an insert or element (1), advantageously of generally cylindrical form, having substantially smooth lateral and end-face exterior surfaces, and advantageously including, on its cylindrical and lateral surfaces, at least one recess (2) of annular form consisting, for example, of an annular recess of curvilinear cross-section with its edges (3) rounded in accordance with a specific radius.

The cylindrical element (1) includes, on its lateral surface and preferably in two diametrically opposed zones, flattened regions (5) of triangular, parabolic or similar form.

The upper end face (6) of the element (1) has, in a central region, a cylindrical opening (7) with an internal screw thread (21) into which opening a screw-threaded peg (8) of a dental piece (16) which it is desired to implant is screwed. Around the top (as shown) of the opening (7), a neck (10) is used to centre the piece (16) in a stable manner.

The dental piece (16) is fitted, in accordance with Figure 6, by positioning the element (1) within a cavity (11) previously made in the jaw (12) with a conventional dentistry instrument. The cavity (11) has a cylindrical configuration with a length and diameter which are slightly greater than the length and diameter, respectively, of the cylindrical element (1) so that, between the internal walls of the cavity (11) and the exterior surface of the element (1), there is a space (13) indicated by shaded lines in Figure 6. All this takes place without the need for interference between the hole in the bone and the insert, which is usual in impacted implants.

The space (13) is filled with a rapid setting, high strength dental adhesive which is applied in a fluid state in the form of a layer of suitable thickness, covering the internal walls of the cavity (11) . The element (1) is inserted immediately after application of the adhesive, resulting in the arrangement which can be seen in Figure 6.

The set adhesive provides a seal between the cylindrical element and walls of the cavity which prevents the occurrence of infections.

The adhesive enters the annular recess (2) and, when hardened, guarantees immobilization, vis-a-vis a possible displacement in the axial direction, of the element (1) in the jaw. Moreover, the provision of the planar zones (5) prevents the element (1) from rotating about its imaginary geometrical axis. Thus once the sealing material hardens, the element (1) is completely immobilized in the jaw, and hard bony regions may even form around it.

When the element (1) is initially placed in the cavity (11) prior to fastening of the dental piece (16), a temporary piece (15), in the form of a threaded stopper, may be screwed into the cavity (7) to prevent the ingress of foreign bodies which might make the subsequent placing of the threaded peg of the dental piece more difficult.

The dental piece (16), shown in cross-section in Figure 5, includes, at its base, a recess (17) , which is shaped to receive in a complementary manner the projection or neck (10), for stabilizing the position of the piece where it is implanted. The dental piece (16) further has an opening (18) which communicates with the recess (17) via a cylindrical axial opening (19). The openings (18 and 19) allow the head (20) of the screw-threaded peg (8) to be seated after the peg has been screwed into the screwthreaded opening (7) of the element (1).

In the case shown in Figure 7, two parts (22) and (23) of a fractured bone are joined together by a connecting plate (24) positioned outside the bone parts. The bone parts (22, 23) have cavities (27) and (28) formed therein in which elements (25, 26), each similar to the element (1) described above, are adhesively fastened. Screw-threaded tenons or bolts (29) and (30) are screwed into screwthreaded sockets of the elements (25, 26) and retain the connecting plate (24) in position to fasten the bone parts (22 and 23) together.

The existence of a single thread (the internal thread (21) in the opening (7)) in the element (1) , prevents possible weakening of the cylindrical wall of the element, which would be brought about (given its reduced thickness) if there were another thread on the exterior of the element.

This is essentially smooth on its external surface.

It should be pointed out that any variation in the exterior forms and dimensions of the device and materials used in its practical embodiment will not alter the essential nature of the device, which is summarized in the following claims.

The invention has been described in particular with reference to fastening artificial means to bones or bone parts of a human body. However the invention is also applicable to fastening artificial means to parts of an animal.

Claims (9)

1. A device for fastening artificial means to a body bone part, comprising an insert of strong material which is compatible with bony tissues, the insert having a substantially smooth external surface provided with geometrical means for immobilizing the insert when the latter is received within a body bone part and, in a central region, a threaded socket suitable for receiving a threaded part of artificial means, the insert in use being intended to be housed within a recess in a body bone part having slightly greater dimensions than the insert, a layer of adhesive material in the fluid state and which is able to harden rapidly being interposed in the intermediate spaced defined between the insert and walls of the recess.

2. A device according to claim 1, in which said geometrical means for immobilizing the body comprises symmetrical and/or asymmetrical recesses, which are preferably of annular and of curvilinear cross-section, and planar zones (5) covering all or part of the length of the insert.

3. A device according to claim 1 or 2, in which said insert is substantially cylindrical.

4. A method of fastening artificial means to at least one body bone part comprising adhering at least one insert having a screw-threaded socket within at least one recess of said body bone part(s) and screwing a part or parts of the artificial means into the screw-threaded socket(s).

5. A method according to claim 4, in which the or each of said recesses is formed, e.g. by drilling, in the bone part(s) prior to adhering the insert therein.

6. A method according to claim 4 or 5, in which the artificial means comprises a dental part.

7. A method according to claim 4 or 5, in which two of said inserts are adhered within recesses in two adjacent body bone parts and in which said artificial means has screw-threaded members received in the screw-threaded sockets which anchor a connecting piece connecting said body bone parts together.

8. A body fastening system comprising a substantially cylindrical insert adhesively secured within a recess of a body bone part, the insert having a substantially smooth exterior surface provided with geometrical means for immobilising the insert within said recess and also having a screw-threaded socket, and artificial means having a screw-threaded member screwthreadedly received in said socket for fastening the member to the body bone part.

9. A fastening device substantially as herein described with reference to, and as illustrated in, Figures 1 to 6 or Figure 7 of the accompanying drawings.