ARRANGEMENT FOR OBTAINING RELIABLE ANCHORING OF A THREADED IMPLANT IN BONE

Abstract: In an arrangement for obtaining reliable anchoring of a threaded implant (3) in dentine, a hole (2) is made in the bone substance. In the side wall (2b) of the hole it is possible to establish an internal threading which can cooperate with an external threading (3d) on the implant. The implant threading is arranged to force the bone substance out in essentially radial directions as a function of the extent to which the implant is screwed into the hole. The threading is arranged to effect greater forcing out of the bone substance at the outer parts of the hole than at the inner parts of the hole. The degree of forcing out is adapted in relation to the softness of the bone in order to achieve the reliable anchoring. Along at least part of the longitudinal direction of the implant, the implant threading can be given a non-circular configuration for the purpose of obtaining improved rotational stability in soft/weak bone. The implant can also have two or more thread spirals/thread entries which shorten the time for screwing the implant into the hole and additionally offer tight threading which permits effective integration with the bone substance during the healing-in process.

Description: T ITLE ARRANGEMENT FOR OBTAINING RELIABLE ANCHORING OF A THREADED IMPLANT IN BONE TECHNICAL FIELD: The present invention relates to an arrangement permitting anchoring of a threaded implant in Done, for example dentine, m the human body by means of a screwing/tightening instrument. At its upper part, the implant has an anchoring hole for a unit, preferably in the form of a screw, intended to secure an element that can be attached to the implant and can in this case consist of a fixture holder, fixture, spacer, etc. The centre axis of the anchoring hole is also inclined in relation to the longitudinal axis of the implant. The invention also relates to the use of an element, for example n the form of a fixture holder, fixture, spacer, etc., which can be attached to a threaded implant, where the implant is screwed into a bone, for example the dentine, by means of an instrument and where the implant has an anchoring hole for the securing unit, preferably in the form of a screw, for tne element in question. PRIOR ART The invention is further concerned with the screwing functions of implants of the type described, inter alia, in Swedish Patent 9203563-3 and PCT application WO 96/18355. A characteristic of this type of implant is the presence of an inclined threaded hole which can be arranged in a fixture for the implant or in the actual implant itself. The centre axis of the hole is inclined in relation to the axis of rotation of the implant. When anchoring further fixtures, spacers, etc. in the implant, an anchoring screw is used which can be screwed tightly into the internal thread of the anchoring hole. The said PCT document mentions the possibility of using screwing instruments which are connected to the upper parts of the implant for the purpose of screwing the implant tightly into the bone in question. DESCRIPTION OF THE INVENTION TECHNICAL PROBLEM A reliable and as far as possible simplified tightening function needs to be found. The invention is intended to solve this problem, among others. The said PCT document proposes an instrument which uses the anchoring screw for securing a fixture to the implant. The instrument is provided with an inclined recess which coincides with or constitutes a continuation of the anchoring hole. The anchoring screw is in this case removed first, and the instrument is applied in such a way that the recess of the instrument is arranged concentrically in relation to the recess in the implant, after which they can be screwed tight by means of the said anchoring screw. When the implant has been tightened, the anchoring screw is loosened and removed, after which the instrument can also be removed. This procedure is a lengthy one. The inclined recess in the instrument is deep and problems can occur during screwing, unscrewing, etc., of the anchoring screw in question. The present invention is intended to solve this problem too. It may be desirable not to have to act on the anchoring screw during the tightening or screwing-in of the implant into the bone. The invention solves this problem too. SOLUTION The feature which can principally be regarded as characterizing an arrangement according to the invention is, inter alia, that the element (fixture holder, fixture, etc.) that can be attached by means of the said unit (screw) is provided with means of cooperation with the instrument, and that the element and its means of cooperation are arranged to permit application of the instrument in a way which ensures that the axis of rotation of the instrument essentially coincides with the continuation of the axis of rotation of the implant. An arrangement according to the invention can principally be regarded as being characterized by the fact that the tightening function exerted by means of the instrument is separate from the securing function exerted by means of the unit (screw) by virtue of the fact that the element (fixture holder, fixture, spacer, etc.) has a first portion via which the element is anchored by the anchoring unit in the implant, and a second portion which is separate from the first portion and which has cooperating means for the instrument. Embodiments of the arrangement are specified in the attached subclaims . The use according to the invention can principally be regarded as being characterized by the fact that the element (fixture holder, fixture, spacer, etc.) is used in the tightening operation with the instrument by virtue of the fact that the element has means cooperating with the instrument, to which means the instrument is applied with its axis of rotation essentially coinciding with the continuation of the axis of rotation of the implant. Further developments of the said use are specified in the attached subclaims. ADVANTAGES By means of what has been proposed above, a considerably simplified and less expensive tightening function is obtained for implants in dentine. The handling of small tightening screws can be avoided, and simple application to the implant for turning it or screwing it in can be effected. The locking function for the instrument can be made extremely simple by the fact that a conventional locking screw can be used in a manner known per se. The implant with associated element, i.e. fixture holder, fixture, spacer, etc., can be supplied as one unit to which the tightening instrument can be applied in an extremely simple and effective manner. DESCRIPTION OF THE FIGURES A presently proposed embodiment of an arrangement and use having the significant characteristics of the invention will be described below with reference to the attached drawings, in which: Figure 1 shows, in a vertical view and partial cross section, an implant which has been partially screwed into dentine by means of an instrument (screwing instrument) , Figure 2 shows, in a vertical section, and enlarged in relation to Figure 1, the implant together with a fixture holder screwed into the latter, Figure 3 is a plan view of means which are arranged on the upper part of the fixture holder and can cooperate with the instrument, Figure 4 shows, in vertical section along the line A-A, the design of the fixture holder, Figure 5 shows, obliquely from above, the design of a nut-shaped part on the implant, and Figure 6 shows the upper parts of the implant from the side, with the associated nut-shaped part according to Figure 5. DETAILED EMBODIMENT In Figures 1 and 2, an implant is indicated by 1. The implant is intended to be screwed into dentine 2, and it can be screwed into a pre-drilled hole 3. The implant can be of the self-tapping type and is in this case provided with an external thread la. Attached to the upper parts of the implant there is an element 4, for example in the form of a fixture holder. This can be attached or applied by means of a screw 5 or other anchoring unit. An instrument, for example in the form of a screwing instrument 6 with shaft-like part 6a and handle part 6b, can be attached/applied to the upper parts or portion 4a of the element. The instrument is provided with a locking arrangement, for example in the form of a locking screw 7. The fixture holder 4 is provided with a second portion 4b which is separate from the first portion 4a. The axis of rotation (longitudinal axis) of the implant is indicated by lb, and the longitudinal axis or axis of rotation of the screw 5 is shown by 5a. The implant has an inclined, threaded recess lc, in which the screw 5 can be screwed or the unit can be anchored. The centre axis of the hole coincides with the centre axis 5a of the screw. The centre axis of the hole slopes at an angle, for example an angle of about 45°, in relation to the longitudinal axis lb of the implant. The said second portion 4b has a recess 4c which is concentric in relation to the recess lc when the holder is in its secured position on the implant. The head 5b of the screw 5 is partially engaged in the recess 4c when the holder is in its secured position in the implant. The upper portion 4a of the holder 4 is provided with a key grip 4d. The holder 4 is additionally provided with a central recess 4e (can be threaded) which opens at the top, and a transverse recess 4f in the bottom part of the recess. The centre line 4g of the holder coincides essentially with the axis of rotation lb of the implant. The centre line of the hole 4e coincides with the centre line 4g of the holder 4. A shoulder portion of the holder is shown by 4h. The upper part of the implant is shown by Id. Figure 3 shows a four-sided key grip for the instrument 6 which is provided with a corresponding internal four- wall recess 6c (Figure 1) . The key grip can have another number of sides, and the recess 6c likewise can have another number of corresponding walls. The part bearing the shoulder portion 4h can have a diameter of about 6 mm, and the external dimension d of the key grip can be about 3.9 mm. Figure 4 shows that the recess 4c passes into subsidiary recesses 4c' and 4c' ' , of which 4c' is threaded. The diameter of the recess 4c' is less than the diameter of the recess 4c so as to form a shoulder 4c''' with which an underside 5b' (see Figure 2) of the screw 5 cooperates or on which it bears when the screw is in the screwed-in position. The holder 4 has an inclined surface 4i which slopes at an angle α of about 45° in relation to the axis 4g. Figures 5 and 6 show the outer shape of the implant which in this case comprises a hexagonal nut lc to which the holder 4 can be fixed in rotation by means of the recess 4c' which is designed with an internal hexagon shape corresponding to the outer shape of lc. Other numbers of edges can be used. The method can in this case be that the holder is first anchored to the implant by the recess 4c' ' being brought over the nut shape lc and the member 5 thereafter being applied and made fast (screwed) . The instrument can thereafter be engaged on the four-edged shape 4d via its corresponding four-edged recess 6d, after which the locking member 7 is activated (the locking nut is tightened) . When the implant is screwed fully into the dentine 2, the locking member 7 is deactivated and the instrument 6 is removed from the holder 4, which in this way can be left in place, i.e. the unit or the screw 5 does not need to be removed, screwed tight and once again removed in order finally to be screwed back again into the respective recess. The new arrangement is thus characterized by the fact that the tightening function exerted by means of the instrument is separate from the securing function which is exerted by the said unit or screw 5. The said functions are attributable to different parts of the holder, spacer, fixture, etc., which parts are thus separate or distinct. One element, for example in the form of a holder according to the above, can in this case be used in the screwing function by means of the instrument, the instrument being applied in such a way that the instrument 6d coincides with the longitudinal axis lb of the implant. Reference is made to Figure 1 where it can be seen that the direction of the longitudinal axis 6d of the instrument coincides with the continuations of the longitudinal axes lb and 4g, respectively, of the implant and of the fixture holder. Figure 6 shows an inclined surface of the implant indicated by le. This surface slopes in relation to the longitudinal axis lb of the implant by an angle α' which essentially corresponds to the angle α in Figure 4. The arrangement is also such that when the surfaces 4i and le bear against each other, the longitudinal axes 4g and lb essentially coincide, which is also true of the longitudinal axis 6d of the instrument since the key grip 4d is arranged concentrically around the longitudinal axis 4g of the holder. The invention is not limited to the embodiment shown above by way of example, but can be modified within the scope of the attached patent claims and the inventive concept .

Claims: PATENT CLAIMS 1. Arrangement permitting anchoring of a threaded implant (1) in bone, for example dentine (2), in the human body by means of a screwing instrument (6), the implant having, at its upper part, an anchoring hole (lc) for a unit (screw) intended to secure an element (4) that can be attached to the implant, for example a fixture holder, fixture, spacer, etc., and the centre axis (5a) of the anchoring hole being inclined in relation to the longitudinal axis (lb) of the implant, characterized in that the element (fixture holder, fixture, spacer, etc.) that can be attached by means of the said unit (screw) is provided with means (4d) for cooperation with the instrument (6), and m that the element and its means of cooperation are arranged to permit application of the instrument m a way which ensures that the axis of rotation (6d) of the instrument essentially coincides with a continuation of the longitudinal axis (lb) of the implant. 2. Arrangement according to Patent Claim 1, characterized m that the centre axis (4g) of the element, m the longitudinal extent of the element, essentially coincides with the said continuation, and in that a key grip is arranged concentrically around the centre axis of the element, at the upper part (4a) of the element. 3. Arrangement according to Patent Claim 1 or 2, characterized in that the element has, at its portion cooperating with the upper part (Id) of the implant, an inclined surface (4ι) which can be applied against a corresponding inclined surface (le) on the implant. 4. Arrangement according to any of Patent Claims 1, 2 or 3, characterized in that the element is arranged with a rotationally fixed attachment relative to the implant, and in that the element, at its portion corresponding to the rotationally fixed attachment, is provided with an inclined recess which is concentric in relation to the anchoring hole (lc) , and in that the outer part (5b) of the unit can be at least partially engaged in the said inclined recess (lc). 5. Arrangement according to any of the preceding patent claims, characterized in that the screwing instrument (6) is provided with a locking arrangement, for example comprising a locking screw (7), for locking the instrument to the cooperating means (4d) of the element . 6. Arrangement according to any of the preceding patent claims, characterized in that the element is designed with a key grip with two or more edges, for example four edges, and in that the instrument (6), at its part cooperating with the element so that the latter can be turned, is provided with a recess having straight wall parts, the number of which corresponds to the number of edges. 7. Arrangement according to any of the preceding patent claims, characterized in that the instrument has a shaft-like part (6a) which at its free end supports the members (6c) cooperating with the element, and a handle part (6b) by means of which the rotational movement can be exerted on the instrument when screwing the implant into place. 8. Arrangement according to any of the preceding patent claims, characterized in that the element has a flange and a threaded hole (4e) for securing additional dental members (fixture, spacer, etc.), and, where appropriate, a hole (4f) which extends under the bottom of the said threaded hole, in the transverse direction, and which can be a through-opening. 9. Arrangement permitting anchoring of a threaded implant (1) in bone (2), for example dentine, in the human body by means of a screwing instrument (6), the implant having, at its upper part, an anchoring hole (lc) for a unit (screw) intended to secure an element that can be attached to the implant, for example a fixture holder, fixture, spacer, etc., and the centre axis of the anchoring hole being inclined in relation to the longitudinal axis (lb) of the implant, characterized in that the tightening function exerted by means of the instrument is separate from the securing function exerted by means of the unit by virtue of the fact that the element (4) has a first portion (4b) via which it is anchored by the anchoring unit (5) in the implant, and a second portion (4a) which is separate from the first portion (4b) and which has cooperating means (4d) for the instrument (6). 10. Use of an element, for example fixture holder, fixture, spacer, etc., which can be attached to a threaded implant, where the implant is screwed into a bone (2), for example the dentine, in the human body by means of an instrument (6) and where the implant has an anchoring hole for the securing unit (screw) for the element, the centre axis of the anchoring hole being inclined in relation to the axis of rotation (lb) of the implant, characterized in that the element (4) is used in the screwing operation with the instrument by virtue of the element having means (4d) cooperating with the instrument, to which means (4d) the instrument is applied with its axis of rotation (6d) essentially coinciding with a continuation of the axis of rotation (lb) of the implant. 11. Use according to Patent Claim 10, characterized in that the element (4) is used to form a key grip (4d) for the corresponding key grip (6c) on the instrument (6) .

Inventors: CARLSSON LENNART, ENGMAN FREDRIK, FROMELL ROGER, JOERNEUS LARS, CARLSSON, LENNART, ENGMAN, FREDRIK, FROMELL, ROGER, JOERNEUS, LARS
Applicants: CARLSSON LENNART, ENGMAN FREDRIK, FROMELL ROGER, JOERNEUS LARS, NOBEL BIOCARE AB, CARLSSON, LENNART, ENGMAN, FREDRIK, FROMELL, ROGER, JOERNEUS, LARS, NOBEL BIOCARE AB (PUBL)
Application year: 1998
Main classification: A61C8
IPC codes: A61C8, A61F2, A61L27