US3732621A

US3732621A - Permanently implantable fixture means for prothesis and the like

Info

Publication number: US3732621A
Application number: US00123707A
Authority: US
Inventors: B Bostrom
Original assignee: AGA AB
Current assignee: AGA AB
Priority date: 1970-03-25
Filing date: 1971-03-12
Publication date: 1973-05-15
Anticipated expiration: 1990-05-15
Also published as: SE328961B; ZA711728B; FR2085013A5; DE2114323A1; DE2114323B2; GB1352188A; CA958852A; DE2114323C3

Abstract

As a permanently implantable fixture means for prosthesis and the like in a human body, especially for implanting a dental prosthetic structure, a means composed by at least two parts has been proposed for attaching the prosthetic structure to bone tissue. A first part of the attachment unit is intended to be applied in such a way in the bone tissue that it will remain embedded in said tissue during all of the time required for healing the damage which occurs when the first part is attached to the bone and while the bone tissue grows into the attachment, and a second part of the attachment unit, serving as mounting unit for the prosthetic structure and so shaped that it may be attached to the first part of the attachment unit and pass through such weak tissue covering the bone tissue. The mounting unit is intended to combine the attachment unit inserted into the bone tissue with a prosthetic structure located outside of the weak tissue. Such permanently implantable attachment means have been used for permanently attaching dental prosthetic structure to the jawbone in human bodies. The jawbones rather often have a narrow crosssection, and the longitudinal direction of the cross-section may be diverge sharply at different parts of the same jaw and/or the same jawbone but especially between the upper jaw and the lower jaw. This, among other reasons, results in so-called over-bite or under-bite, respectively. As the attachment units must, for technical reasons, be well centered in the jawbone, the longitudinal directions of the attachment units will not always be in alignment mutually in the same jaw, nor between the upper jaw and the lower jaw. This is a serious disadvantage, because the longitudinal direction of the teeth in the prosthetic structure should be in alignment with the longitudinal direction of the attachment unit. A compromise between these demands either a weak or completely unsatisfactory attachment in the jawbone or non-aligned prosthetic structure. Therefore, there is a need for an attachment means of the kind indicated above, in which the said first part attached to the jawbone may form an angle with the said second part to which the prosthetic structure is attached.

Description

nited States Patent 1 Bostrom [54] PERMANENTLY IMPLANTABLE FIXTURE MEANS FOR PROTHESIS AND THE LIKE Bertil l. Bostrb'm, Taby, Sweden [73] Assignee: AGA Aktiebolag,

Stockholm, Sweden [22] Filed: Mar. 12, 1971 [21] Appl. N0.: 123,707

[75] Inventor:

Ligingo near Primary ExaminerRobert Peshock Altorney- Larson, Taylor & Hinds [57] ABSTRACT As a permanently implantable fixture means for prosthesis and the like in a human body, especially for implanting a dental prosthetic structure, a means composed by at least two parts has been proposed for attaching the prosthetic structure to bone tissue. A first part of the attachment unit is intended to be applied in such a way in the bone tissue that it will remain embedded in said tissue during all of the time required 1 3,732,621 [451 May 15,1973

for healing the damage which occurs when the first part is attached to the bone and while the bone tissue grows into the attachment, and a second part of the attachment unit, serving as mounting unit for the prosthetic structure and so shaped that it may be attached to the first part of the attachment unit and pass through such weak tissue covering the bone tissue. The mounting unit is intended to combine the attachment unit inserted into the bone tissue with a prosthetic structure located outside of the weak tissue.

Such permanently implantable attachment means have been used for permanently attaching dental prosthetic structure to the jawbone in human bodies. The jawbones rather often have a narrow cross-section, and the longitudinal direction of the cross-section may be diverge sharply at different parts of the same jaw and/or the same jawbone but especially between the upper jaw and the lower jaw. This, among other reasons, results in so-called over-bite or under-bite, respectively. As the attachment units must, for technical reasons, be well centered in the jawbone, the longitudinal directions of the attachment units will not always be in alignment mutually in the same jaw, nor between the upper jaw and the lower jaw. This is a serious disadvantage, because the longitudinal direction of the teeth in the prosthetic structure should be in alignment with the longitudinal direction of the attachment unit. A compromise between these demands either a weak or completely unsatisfactory attachment in the jawbone or non-aligned prosthetic structure. Therefore, there is a need for an attachment means of the kind indicated above, in which the said first part attached to the jawbone may form an angle with the said second part to which the prosthetic structure is attached.

20 Claims, 7 Drawing Figures PATENTEU MAY 1 51975 Fig.6

SHEET '4 UF 4 Fig.7

PERMANENTLY IMPLANTABLE FIXTURE MEANS FOR PROTHESIS AND THE LIKE The present invention refers to an arrangement in attachment means of the above indicated kind, by which said need is satisfied.

According to the invention, there is provided between the part of the attachment means intended to grow together with the bone tissue, on the one hand, and the part of the attachment means which carries up the prosthetic structure on the other hand, a ball joint like arrangement, comprising at least one joint but perhaps two or more joints.

Further details of the invention will be apparent from the-following description in connection with the attached drawings, showing a number of different forms of execution of the invention. However, it is understood that the invention shall not be limited to one or more or all of these forms of execution, but that all different modifications or combinations between the different forms of execution may be made within the different parts of the same jaw and/or the same jaw bone but in first place between the upper jaw and the lower jaw. This, amongst others, results in what is called overbite or under-bite, respectively. As the attachment units have for load technical reasons to be well centered in the jaw bones, the longitudinal directions of the attachment units will not always be in agreement mutually in the same jaw, nor between the upper jaw and the lower jaw. This means a serious disadvantage, because the longitudinal direction of the teeth in the prothesis should be in agreement with the longitudinal direction of the attachment unit. A compromise between these demands causes a weak or completely dissatisfactory attachment in the jaw bone or that the tooth prothesis will be wrongly directed.

Therefore, there is a need for an attachment means of the kind indicated above, in which the part, growing together with the jaw bone, may form an angle with the part, to which the prothesis should be attached.

The present invention refers to an arrangement in attachment means of the above indicated kind, by which said need is satisfied.

According to the invention, there is provided between the part of the attachment means intended to grow together with the skeleton tissue, on the one hand, and the part of the attachment means, which shall carry up the prothesis, on the other side, a ball joint like arrangement, comprising at least one joint but perhaps two or more joints.

Further details of the invention will be apparent from the following description in connection with the at tachmed drawings, showing a number of different forms of execution of the invention. However, it is understood that the invention shall not be limited to one or more or all of these forms of execution, but that all different kinds of modifications or combinations between the different forms of execution may be made within the frame of the invention.

In the drawings,

FIG. 1 shows an arrangement according to the invention, in which only one single gall joint appears, and in which the ball is applied on the part of the attachment means intended to grow' into the bone tissue, whereas the ball claw cooperating with the ball is applied on the part to which the prosthetic structure is intended to be attached.

FIG. 2 shows an arrangement in which the two means contained in the ball joint are applied in the opposite way, and

FIG. 3 shows the same arrangement as in FIG. 2, but doubled so that there are two ball joints in cascade. In all of the said three forms of execution there is a ball claw for clamping the ball.

FIG. 4, however, shows an arrangement in which the ball claw has been replaced by a stretch joint arrangement, running through part of the contact surface of the ball joint, and

FIG. 5 shows the corresponding arrangement with a spherical ball.

FIGS. 6 and 7 show a variation of the arrangement according to FIG. 2.

In the arrangement according to FIG. 1 the part growing together with the jawbone comprises a bolt formed part 10, which is provided with outside threads for screwing the same into a hole drilled in the jawbone and provided with inside threads. The part 10 further is provided with a well 11 entering from below, which communicates through radially directed openings 12 with the outside of the part 10 which is provided with the threads 13. The holes are intended for making it possible for bone tissue to grow in, in connection with the part 10 growing together with the bone tissue. At the upper end the part 10 is provided with a flange 14, having an L-formed section for the reception of a free collar 15, which forms, on its inner side, the socket for reception of the ball 16 in the above mentioned ball joint. Hereinafter, the term socket shall be understood as any means for retaining a ball in its position contained in the ball joint, independently of whether this part is cup-formed or perhaps for instance clawformed. However, it may happen that a separate ball claw is applied between the ball and the socket. This ball claw initially is open, but is staved after the introduction of the ball, so that it will permanently embrace the ball. The ball claw may be cut up or closed all around.

The ball 16 is attached to a shaft 17, which is provided at its lower end with threads and is screwed into the bolt-formed part 10, said part for this purpose being provided with a well 18 having inside threads. Between the concave part of the collar 15 forming the socket, and the convex spherical part of the ball 16, a ball claw 19 is placed, which is attached to the upper part 20 of the attachment means. This part 20 is built up in such a way that it will give a good fixture for the prosthetic structure 21, but this detail does not form the subject of the present invention per se, and it will therefore also not be further described here. The upper part 20, however, is drilled through with a hole 22, running in the axial direction and inwardly threaded, in the threads of which it is possible to screw in a bolt 23 along with an arrangement for moving bolt 23 axially, for instance a screw driver groove 24. In FIG. 1 the screw driver groove and the parts of the cavity within the part 20 adjacent the groove 24 have been shown to be filled with cement, amalgame or any similar filler mass. The bolt 23, at its lower end, is provided with a preferably conical cavity 25 having such a top angle that, when the bolt is drawn in, the edges of the cavity will mesh with the ball 16 and lock this against mutual movement between the ball 16 and the upper part 20 of the attachment means.

When an attachment means of the kind described above is to be attached to the jawbone of a patient, requiring a permanently implanted prosthetic structure 21, the dental surgeon acts so that he will first drill, and if required provide threads in the opening in the jawbone for the lower part of the attachment means. Thereby he can determine the axial direction of the opening so that this opening in the jawbone will in the best possible way be centered in the jawbone, and so that it will not get in the immediate vicinity of the surface parts of the jaw bone. In many a case, however, because of the form of the jaw bone the drilled hole runs in a direction, the axis of which forms an angle with the direction which the upper part 20 of the attachment means must assume basis of the form for proper alignment of the prosthetic structure. In the drilled and threaded hole thereafter the dental surgeon screws in the lower part 10 of the attachment means, after which he puts a temporary sealing arrangement of some suitable kind in the mouth of the patient and perhaps also on the threaded hole 18 in the lower part 10, and he folds over the weak tissue, folded away at the earlier treatment, in order to heal this, and also to heal the damages caused in the jawbone. Simultaneously the lower part 10 is allowed to grow together with the bone tissue or other hard tissue growing together with the outer surface of the lower part 10, which has for this purpose been rifled or in any other suitable way made uneven. Further, bone tissue will grow into the hole 12. Screwing up the lower part 10 thereafter is effectively prevented.

The lower part 10 thereafter is left in the way mentioned above to grow together with the jawbone, which usually will take approximately six weeks. After healing is completed, the dental surgeon again cuts up the weak tissue over the lower part 10, which has now been healed, and he uncovers the lower part, screwed into the threaded hole 18, along with its cover screw by folding away and/or operating away skin and gums and he removes the cover screw and screws in the bolt 17 along with the ball, after having applied the collar in its place. At this time the part and the bolt 17 assume a straight line and are locked in this position by means of the screw 22. When the bolt 17 is completely screwed into the hole 18 so that the part 19 is in contact with the socket 15 the screw 20 is slightly released and the part 20 is turned to the desired direction. After the part 20 has thus been placed in the correct direction, is again locked in this position by means of the screw 22, so that it cannot be moved any further. When all attachments are mounted according to the above, the dentist makes a print, and guided by this the tooth technician thereafter makes a prosthetic structure, which may be cemented to the part 20.

In this connection it should be observed that the attachment means according to the present invention may, of course, be used for attachment of a prosthetic structure in the lower jaw as well as for attachment of a prosthetic structure in the upper jaw. Hereinafter the terms lower" and an upper part refer to the use of the attachment means for attachment of a prosthetic structure to the lower jaw. Normally, for a complete prosthesis, a plurality of such attachment means are required, but it will be apparent to the dental surgeon in any specific case how the prosthetic structure should be distributed along the jawbone in order to give a satisfactory attachment. For that reason only one single attachment means is shown in the drawings. Of course, the same attachment means may be used for attachment of a prosthetic structure, representing a single tooth.

FIG. 2 shows a variation of the arrangement according to FIG. 1. The lower part 27 of the attachment means has been shown here only schematically. One may directly screw this lower part into the drilled and threaded hole in the jawbone, but it is also possible to let the lower part 27 replace the bolt 18 in the arrangement according to FIG. 1. The essential difference between the arrangements according to FIG. 1 and FIG. 2 concerns the arrangement of the ball joint.

In the arrangement according to FIG. 2 the ball claw 28 is provided in a direction upwardly and made in one piece with the lower part 27. It encloses in itself a ball 29, which is oval in cross-section, said ball being provided with a threaded hole 30 for reception of a downwardly directed pin 31, made in the same piece as the attachment pin 32 for the prosthetic structure 33. By the pin 31 being threaded on its outside for threadedly engaging the inwardly threaded hole through the ball 29, all of the ball joint may be locked in its adjusted position by turning all of the pin construction 31 32, whereby the ball claw 28 is clamped between the ball 29 and the socket 15.

The attachment of the prosthetic structure 33 may in the arrangement according to FIG. 2 take place in the same way as already described in connection with FIG. 1, but it may also take place in such a way that a screw 34 is screwed down through the prosthetic structure 33 and into a threaded hole 35 in the pin 32.

FIG. 3 shows a modification of the arrangement according to FIG. 2, in which one has provided for the possibility that a parallel displacement must take place between the lower and the upper part of the attachment means, perhaps in connection with a change of direction. This makes it necessary have two ball joints, which have been shown in FIG. 3 to each of which would be made in the same way as the single ball joint according to FIG. 2 the two ball joints being interconnected by a central part 32. For this reason also the same reference numerals have been used, however the numerals for the lower ball joint are provided with a prime and the numerals of upper ball joint are provided with a double prime.

The locking of the ball joint need not necessarily take place by means of a locking bolt of the type shown in the earlier forms of execution, but it may also advantageously take place by means of a thread, a wire or the like. In this way the

ball claw

19 or 28, resp., according to the FIGS. 1 3 may be avoided. An arrangement of the last mentioned type is shown in FIG. 4.

In this case, therefore, no such ball claw as shown in FIG. 1 at 19 and in FIGS. 2 and 3 at 28 required, because in place thereof a thread formed means, for instance a wire 36 has been provided. The ball is attached in FIG. 4 to the upper end of the lower part 27 of the attachment means and forms there a semi-spherical calotte with a rather wide recess 37, which should preferably be close to or completely frustro-conical. From the bottom of the recess 37 a well 38 is drilled in a direction downwardly into the lower part 27 of the attachment means. This well suitably is provided with threads for attachment of a plug 39 with a central bore, through which the wire 36 runs under such circumstances that it will be retained in a given position against drawing, when the plug is screwed into the well. The socket 40 cooperating with the ball 16 is in this case formed at the lower end of the upper part of the attachment means 20, and also this concave calotte surface is provided with a recess for the wire 36, so that it may run in stretched state through both of these recesses, even if there should exist an essential angular difference between the lower part 27 and the upper part of the attachment means.

In the upper part 20 of the attachment means there is provided some suitable arrangement for stretching the wire 36, after the upper attachment means part 20 has been placed in correct angular position in relation to the lower attachment means part 27. This stretching device may, as shown in FIG. 4, comprise a piston 41 threaded into a bore in the part 20 running quite through it and provided with internal threads, and further being provided with a hole for the attachment of the wire 36, which is widened at its upper part in the form of an inwardly threaded well 42. The wire is attached to the hole, so that it is stretched, when the piston 41 is screwed upwardly. The attachment of the prosthetic structure 48 may suitably take place by means of a sleeve 45.

Another form of the arrangement according to FIG. 4 is shown in FIG. 5. In this case the ball 49 is not mechanically combined with the lower part of the attachment means, nor with the upper part thereof. It is spherical, but it contains two conical recesses opposing each other and meeting in the center part of the ball. The conical recesses 50 and 51 have, at the place of meeting, such a width that the wire 36 may pass through the ball. The wire 36, as earlier described, is stretched at both ends. Thus, a conventional wire lock 52 is provided in the interior of the lower part 27 of the attachment means. This wire lock comprises two

cupformed parts

53, 54, directed in opposite direction directions with respect to the open, interior parts thereof, said parts being inwardly provided with hooks for attachment with the surface of the wire, and outwardly they are conical in order to be pressed together by pressure from the inwardly conical wall of the hole through the lower part 27 of the attachment means. A screw spring 55 spans the space between a washer 56 and the lower surface of the two

cups

53, 54 in order to press them upwardly into the narrower part of the conical hole in the lower part 27. At its upper end the wire is attached to the piston 41 by means of a hole in this, which is also conical, and in which the end of the wire 36 is mounted after having been widened by means of a wedge 57. The part 41, as was the case in the arrangement according to FIG. 4, is screwed into an inwardly threaded hole in the upper part 40 of the attachment means, which carries the prosthetic structure 48.

In the arrangement according to FIG. 6 the ball is substantially semi-spherically formed. The ball 64 is provided with a downwardly directed pin 65, forming the seat of a screw spring 66, the other end of which rests on the bottom, which is in this case completely spherical, of the recess within the ball claw 28. In other respects the arrangement is in essential parts made in the same way as the arrangement according to FIG. 2, and parts corresponding to each other have therefore also been provided with same reference numerals. By means of the screw spring 66 the ball 64 is pressed upwardly onto the ball claw 28, so that by friction between these two parts the ball 64 will be prevented from rotating to turn the screw connected to the part 59.

It may also happen that the dental surgeon during his work with the attachment means will have to turn certain parts while other parts should not be turned. This especially concerns screwing in the threaded parts. For this purpose there is provided an outer six-edged profile 67 on the part 58.

A further six-edge profile 68 is provided on the lower part 27 as seen from the arrangement according to FIG. 7, which is not shown in section. In other parts this is similarily shaped as the arrangement according to FIG. 6. The last mentioned six-edge profile is intended to be used when screwing the lower part 27 into the jawbone.

I claim:

1. A prosthetic device comprising:

a first part having means to be permanently implanted into a bone such that the bone tissue grows into the first part,

a second part including means for attaching the prosthetic structure thereon,

and a joint connecting said first and second parts, said joint being a universal joint permitting at least limited universal movement of the second part relative to the first part, and said joint including means for locking the universal joint in any selected position within the range of said limited universal movement to prevent further relative movement of the first and second parts,

and including means for separating said first and second parts from each other in the vicinity of said universal joint.

2. A prosthetic device according to claim 1, in which said universal joint is a ball and socket joint and wherein the portion of said second part adjacent the joint is adapted to pass through the soft tissue covering the bone tissue into which the first part is permanently implanted.

3. A prosthetic device according to claim 2, wherein the ball of the ball joint is attached to one of said parts and is embraced by a ball claw which is attached to the other of said parts.

4. A prosthetic device according to claim 2, wherein the ball is at least substantially spherical and is attached by means of a neck to its respective part.

5. A prosthetic device according to claim 2, said ball being formed as an elipsoid, ovaloid or the like, and including a pin connecting said ball to the first part.

6. A prosthetic device according to claim 2, said ball being substantially semi-spherical and formed integrally with one of said parts and the socket embracing the semi-spherical surface and attached to the other of said parts, and including a stretching means running through the ball and socket joint and urging said ball and socket together.

7. A prosthetic device according to claim 2, said ball being substantially spherical and resting in sockets in each of the two said parts.

8. A prosthetic device according to claim 3, said ball claw having an opening, and a pin connected to the ball and extending through said opening and connected to the part other than that part to which the ball claw is connected.

9. A prosthetic device according to claim 6, wherein said stretching means includes at least one substantially conical recess passing through the ball for carrying the said stretching means.

10. A prosthetic device according to claim 9, wherein the ball is substantially spherical and includes a pair of inwardly converging conical recesses which meet at the center of the ball to form an opening completely through the ball for said stretching means.

11. A prosthetic device according to claim 2, wherein said locking means comprises a spring means for urging the ball against its socket.

12. A prosthetic device according to claim 11, including a ball claw embracing the said ball, and wherein said locking means includes a threaded engagement between a pin integral with one of said parts and said ball for displacing the ball relative to the ball claw for urging these two parts together.

13. A prosthetic device according to claim 11, wherein said locking means includes stretching means running through the ball and socket joint, the stretching means being attached at one of its ends to one of said first and second parts, and the other end of the stretching means being attached to the other of said first and second parts, and at least one of said parts being displaceable by means of a screw thread arrangement in the axial direction under the stretching of stretching means.

14. A prosthetic device according to claim 3, wherein the ball claw is provided on its outer surface with a profile which facilitates engaging the ball claw to turn the same.

15. A prosthetic device according to claim 3, including a sleeve contacting the outer side of the ball claw with a partially concave surface to form said socket, and a spring means for urging the ball and sleeve together.

16. A prosthetic device according to claim 15, said sleeve being provided on its outside surface with a profile to facilitate turning the same.

17. A prosthetic device according to claim 3, the said ball in the ball joint being incompletely spherical, a spherical portion of the ball engaging the ball claw, and a non-spherical portion of the ball engaging a spring arranged to urge the ball against the ball claw.

18. A prosthetic device according to claim 17, said ball including a pin for connecting the ball with one of said parts, said pin forming a seat for said spring.

19. A prosthetic device according to claim 18, said claw being generally spherical and embracing the ball, said spring resting against a spherical portion of said ball claw.

20. A prosthetic device according to claim 2, including an intermediate part, a first ball and socket joint connecting said intermediate part to said first part and a second ball and socket joint connecting said intermediate part to the said second part.

Claims

1. A prosthetic device comprising: a first part having means to be permanently implanted into a bone such that the bone tissue grows into the first part, a second part including means for attaching the prosthetic structure thereon, and a joint connecting said first and second parts, said joint being a universal joint permitting at least limited universal movement of the second part relative to the first part, and said joint including means for locking the universal joint in any selected position within the range of said limited universal movement to prevent further relative movement of the first and second parts, and including means for separating said first and second parts from each other in the vicinity of said universal joint.