TECHNICAL FIELD The present invention relates inter alia to a method for executing a cemented superstructure on one or more distance member (s) which can respectively be mounted on an implant assigned to it (them) in the jaw (human jaw) by means of a screw member. The invention also relates to an arrangement for such a cemented superstructure in the jaw, where one or more distance member (s) can be mounted on implants assigned to it (them) with the aid of screw members. In the finished state, the superstructure has no access passage for the respective screw member (s). The invention also relates to a set of distance members which can respectively be mounted on an implant assigned to them in the jaw by means of a screw member, where one or more distance member (s) is (are) intended to form part, in the jaw, of a cemented superstructure which, in the finished state, has no access passage for the respective screw member (s).

The invention also relates to a distance member for making possible a cemented superstructure in the jaw, which member can be fastened to the implant in the jaw by means of a screw member.

STATE OF THE ART It is previously known to form a cemented superstructure on distance members anchored in implants in the human jaw. It is also previously known to design distance members with counterholders in order to prevent the transmission of torsional or torque forces to the implant in connection with tightening by means of tools.

As an example of other counterholding functions in connection with such tools, refer inter alia to Swedish patent 466 786. It is also previously known to

individually adapt distance members to different dental situations. In different dental situations, it is also previously known to make use of screw member sets, from which the selection for the situation concerned can be made.

DESCRIPTION OF THE INVENTION TECHNICAL PROBLEM In a cemented superstructure, problems arise inter alia because there are no access holes for the respective screw member (s) in the finished structure.

During adjustment and repair work in such structures, difficulties thus occur with regard to freeing these structures from the implants without the risk arising of the structure and/or the implants being destroyed.

Measures aimed at reducing to the greatest possible extent the requirement for carrying out repair work on finished superstructures involve placing special demands on the screw joints so that these do not loosen on the dental bridge or dental crown once it has been completed.

It is also important that the components forming part of the dental bridge or equivalent can be designed and constructed so that the technical dental work is facilitated to the greatest possible extent. Major grinding-down and shape modification work during production of the superstructure and cementing are preferably to be avoided, not least out of consideration for the patient. This also applies to impression-taking and model-production work.

The invention aims to solve inter alia these problems. By means of the invention, it is possible, for example, to obtain a visual indication of the delimiting line of the dental bridge or dental crown in relation to the respective distance piece. By means of the invention, great adaptability to different individual appearances and positions in the jaw is also made possible, which is a necessary prerequisite because of the great individual differences represented by patients. It is also important that the distance member set can provide for shapes that

can be related to existing incorporation-type distance pieces. It is thus important, for example, that the distance members have cone angles that essentially correspond to those of incorporation-type distance pieces so that bone and soft tissue do not get in the way when the distance members are mounted. The invention also solves these problems.

SOLUTION The new method according to the above can mainly be considered to be characterized in that a set of distance members which are intended for different individual dental situations is provided, in that each respective distance member in the set provided is made with an internal counterholder for a tightening tool that is used when tightening the respective screw member, which counterholder prevents torque being transmitted from the tightening tool to the implant during tightening, in that a considerable number, preferably at least 80k, of the distance members in the set are individually externally shaped so as to provide for individual anatomical shapes which are impressed on the cementing function and which are optimized for a number of main types of dental situations, by means of which impression substantial modification work on the respective anatomical shape in connection with construction of the cemented superstructure in the jaw is essentially rendered unnecessary, and in that one or more distance member (s) that is (are) optimum or most practicable for the given dental situation is (are) selected from the set of distance members provided.

An arrangement according to the type indicated in the introduction is characterized by the following combination, that is to say in that each respective distance member is made or provided with an internal counterholder member for a tightening tool, which counterholder member is designed to prevent torque being transmitted from the tool to the respective implant in connection with tightening of the respective screw

member, in that each respective distance member has a prefabricated external shape which is essentially individualized to the given dental situation, and in that the prefabricated individual external shape of the respective distance member is likewise designed to comply with the cementing function requirements involved without the need for substantial shape modification work during construction of the superstructure.

The new set of distance members can mainly be considered to be characterized by the following combination, that is to say in that the distance members are designed with prefabricated individual external shapes which are adapted to main types of different dental situations, in that the prefabricated individual external shape of a considerable proportion, at least 80%, of the set is designed to comply with the cementing function involved without the need for substantial shape modification work during construction of the superstructure in the jaw, and in that each respective distance member is made or provided with an internal counterholder member for a tightening tool, which counterholder member is designed to prevent torque being transmitted from the tool to the implant concerned in connection with tightening of the respective screw member.

Embodiments of the set of distance members emerge from the subclaims below.

A distance member according to the invention can mainly be considered to be characterized by the following combination which is characterized in that the distance member is assigned a prefabricated external shape, in that the prefabricated external shape is individually adapted to a given dental situation for the purpose of rendering unnecessary substantial shape modification work in connection with construction of the superstructure in the jaw, in that the prefabricated shape has a shelf- shape ; projecting part or projecting flange located between the upper and lower parts of the distance member, and in that the distance member is or can be designed

with an internal counterholder which prevents torque being transmitted from the tool to the implant.

Embodiments of the distance member according to the invention emerge from the subclaims below.

ADVANTAGES By means of the above proposals, it is possible to propose a distance member set which complies with a very large number of main types of dental situations, which in turn means that considerable optimization is possible for the majority of dental situations. Use can be made of existing principles with regard to tightening tools with counterholders. Visual indications of the connection of the replacement material to the distance member and implant can be obtained. Grinding and adaptation work can be considerably reduced, as can patient treatment time. The invention can be made applicable for distance members made of various materials (titanium, gold, ceramics etc.).

DESCRIPTION OF THE FIGURES A currently proposed embodiment of the method, the arrangement, the set of distance members and the distance member is to be described below with simultaneous reference to the attached drawings, in which Figures 1-lc show in longitudinal section and side and end views a first exemplary embodiment of a distance member, where the tightening tool has also been indicated symbolically, Figure 2 shows in perspective parts of a lower jaw, into which implants have been surgically inserted, distance members, which have been provided with a superstructure in the form of a dental bridge, being fastened to the implants,- Figure 3 shows in vertical section parts of a human lower jaw and, arranged therein, implants on which a superstructure has

been mounted, and Figures 4-17 show in cross-section and side views a number of distance members of various constructions, which form part of a set.

DETAILED EMBODIMENT Figures 1-lc show a first embodiment of a distance member 1. In Figure 1, dentine is represented symbolically by 2 and soft tissue of the dentine by 3. An implant which has been incorporated into the dentine is designated by 4. The distance member is screwed into the implant by a screw 5 which has an external thread which interacts in a known manner with an internal thread in the implant. The distance member has an upper part la and a lower part lb. A lower surface lc (Figure la) bears against an upper surface on the implant, likewise in a known manner. The distance member is coned upwardly/outwardly from the lower surface lc and the half angle a of the cone is roughly 20°. The length L of the distance member is roughly 11 mm and the length 1 of the lower part lb is roughly 1.5 mm. The lower part lb is provided with an internal hexagonal recess (Figure lb), by means of which the distance member is rotationally fixed relative to the implant which has a hexagonal nut projecting up into the hexagonal recess. The distance member has an internal recess le, in the bottom part of which a counterholder member If is arranged. Via the recess and the counterholder member, a tightening tool 6 for the screw 5 is introduced. The tool may be of a type known per se and include a screwdriver 6a which can be brought into engagement with a screwdriver recess in the screw in a known manner. By means of the counterholder member, torsional forces are prevented from being transmitted from the tool to the body of the distance member and in this way torsional forces are prevented from being transmitted from the tool to the implant 4-. The counterholder member is arranged in a rotationally fixed manner in the recess le, cf. Figure lc.

It is also characteristic of the distance member

1 that it has a transition lg which is made in the form of an upwardly directed (in Figure la) shelf which marks the transition between the upper and lower parts la and lb respectively of the distance piece. According to the exemplary embodiment, the upper part is to be covered by a dental bridge or crown, the material of which is indicated by 7 in Figure 1. The edge of the transition forms a visually noticeable edge which facilitates the work of the dentist and the modelmaker. The diameter D of the transition is roughly 4.5 mm in the case shown. The transition lg is also characterized by a sharp external corner which becomes a concave upwardly directed radius R of roughly 1 mm. The upper part is coned upwardly/inwardly and its half cone angle 9 is roughly 2°.

Figure 2 indicates by 8 a superstructure in the form of a dental bridge on and between two implants 9 and 10. A distance member 11 and 12 respectively according to the above is fastened on each respective implant. The superstructure includes sleeves 13 and 14 respectively and bridge material 15. The jaw is symbolized by 16 and teeth therein by 17.

Figure 3 shows on enlarged scale the superstructure 8'and the bridge material 15'. The visible line or transition is designated here by 18.

Screw tightening by means of the tool 6'is effected in a stage before the application of the cement 15'. The cementing is effected in such a manner that, in the finished state, there are no access holes for the screw members 11'and 12'respectively.

Figure 4 shows in longitudinal section a further embodiment of a distance member. In this case, the upper and lower parts la'and lb'are angled in relation to one another. This means that the length of the lower part (cf. 1 in Figure la) varies around the periphery. In the figure, the centre line of the lower part is indicated by 19 and the centre line of the upper part is indicated by 20. According to the embodiment shown, said centre line is inclined at an angle x of roughly 20°. The recess le'

has as its centre line the centre line 19 of the lower part and in this way the recess extends obliquely in the inclined upper part la'.

Figure 5 shows a further embodiment where the length L'and the diameter D'differ from the corresponding length and diameter in the embodiment described above.

The embodiment according to Figure 6 has the same length L as the embodiment according to Figure la while, on the other hand, the diameter D''differs from the diameters D and D'respectively according to the above.

Figure 7 shows an embodiment with different values for the length L''and the diameter D'''and also the half cone angle ß'. These values may be selected to be roughly 8 mm, roughly 6 mm and roughly 4° respectively.

In the embodiment according to Figure 8, the length 1'has been increased in relation to the embodiments according to the above. In this case, the diameter D'''and the angle ß'apply, cf. above.

In the embodiment according to Figure 9, the distance member has a transition part lh which is essentially cylindrical and is roughly 2 mm long. The angle a'has in this case been selected to be roughly 40°. The diameter D''''has been selected to be roughly 7 mm. The length L and the angle 01 apply in this case.

The embodiment according to Figure 10 shows a variant where the upper and lower parts la'and lb' respectively have been angled in relation to one another in accordance with the embodiment according to Figure 4.

The angle X between the centre lines 19 and 20 is selected to be roughly 15° and zizis selected to be roughly 4°. The angle a 20° is also used in this case. In this case, a length La, representing the length of the upper part, has been selected to be roughly 8 mm.

The embodiment according to Figure 11 differs from the embodiment according to Figure 9 in that the values of the angle X'and the length La'have been changed to roughly 25° and roughly 7.75 mm respectively.

Moreover, the transition between the upper and lower parts is asymmetrical around the periphery with a greatest straight part lh'on the far left in the figure and a sharp transition lg on the far right in the figure.

Moreover, a value of roughly 5.8 mm is used for the diameter D'''''.

The embodiment according to Figure 12 shows a new combination of the values for the length L'', the angle a', the angle ß and the diameter D'''.

Figure 13 shows a further combination of length, angles and diameter.

In Figure 14, the size of the angle a is roughly 35°. Otherwise, the values L'', diameter D''''and angle are used, cf. above.

The embodiment according to Figure 15 uses the values L, angle a', angle diameter D'''', cf. above.

In the embodiment according to Figure 16, a diameter D''''''of roughly 8 mm is used. Moreover, the values for the length L, the angle a', the angle?' and the transition lh are used, cf. above.

The embodiment according to Figure 17 shows a new angled variant where the value of the length La''is roughly 7.7 mm. Moreover, the values L, ß and X as above are used for the length concerned and the angles respectively.

According to the above, angles, lengths and diameters with the same reference designations have the same values, e. g. the designation L has the single length value of roughly 11 mm, the length L''has the single value of roughly 8 mm etc. The various distance pieces have in principle the reference designations 1,1', 1'', r'',r'''etc.

The invention is not limited to the embodiment shown above by way of example but can be subjected to modifications within the scope of the patent claims below and the inventive idea.