The present invention relates to a drill device for forming implant holes in bone, preferably in jaw bone.

The drills are provided with markings for different drill depths and are able to cooperate with units that have bearing surfaces which cooperate with the bone/jaw bone and/or template and which can be applied at selected markings of said markings for determination of the drill depth.

When forming a hole in the jaw bone, it is important to be able to set the correct depth of the hole. Problems may arise when forming a hole, for example in an area far back in the oral cavity, on account of the difficulty of access, and it is an absolute condition that the hole can be made in such a way that the underlying nerves are not damaged during formation of the hole.

It is already known in the first instance to use discshaped or ring-shaped elements for establishing bearing surfaces at the drill markings. The disc-shaped or ring-shaped elements are engaged on the respective drill and are anchored to the drill by means of side screws. Reference may be made in this regard to existing systems (Branemark®, Replace Select Tapered, Replace Select Straight, etc.) which are sold on the open market.

The disc-shaped or ring-shaped elements entail problems, among other things because of their small dimensions and the small screws used to tighten them. It is difficult to secure the disc-shaped or ring- shaped elements so that they are sufficiently precisely oriented with the markings. The disc-shaped or ring- shaped elements can easily come askew, which means that these elements tend to wobble as the drill rotates.

There are also problems associated with cleaning the known constructions. There are risks of said elements and markings being mixed up. Another disadvantage is that the side screws have to be secured using small screw drivers. There is therefore a considerable need for- -radical ^• measures to be taken concerning the application of the bearing surfaces to the markings on the drill. The object of the invention is to solve this problem.

There is also a need to be able to reduce the number of components associated with the drills. It is therefore of interest to be able to use one and the same set of components for different drills and drill types and, for example, to be able to use the set of components on a new drill when the earlier drill has become worn or is destroyed. Thus, for example, the number of sets of components must also be able to be reduced. This cannot be done with individual sleeves which are used in a similar dental context to the present invention. By contrast, the invention solves this problem.

The features that can principally be regarded as characterizing a device according to the invention are that the units mentioned at the outset comprise or consist of a set of sleeves of different lengths and that, at their first ends, the sleeves have first members cooperating with one and same corresponding second member on the respective drill for retention of selected sleeve on selected drill, and, at their other ends, the sleeves have bearing surfaces such that these extend at the markings selected with the lengths of the sleeves.

In further developments of the inventive concept, the first member consists of a first portion with an internal thread, and the second member consists of a second portion with an external thread by means of which the internal thread can cooperate. The thread

direction is such that the direction of tightening coincides with the direction of rotation of the drill.

In an alternative embodiment, the first member can comprise a snap-fit element which, when the respective sleeve is applied to the respective drill, snaps into a

^■ recess 'formed in-the second ^• member. The sleeve lengths are selected to permit bearing against the top surface of the bone/top surface of the gum and also against the top surface of a template. In a further alternative embodiment, the respective sleeve can be clamped securely on the respective drill between a tool, which is used for rotation of the drill, and an opposite surface on the drill.

Further embodiments are set forth in the dependent claims.

By means of what has been proposed above, a number of advantages are afforded over and above the fact that the bearing surfaces can be applied securely in relation to the markings. Among other things, wobbling tendencies are avoided, and the number of drills can be reduced, while one and the same set of sleeves can be used for different drills, i.e. for drills used as replacements for worn drills. With a common starting position, seen from the point of attachment on the drill, the hole depth can be easily determined through the choice of different sleeve lengths. The sleeves are arranged longitudinally on the drill, which means that wobbling tendencies are largely eliminated or avoided. The application of the bearing surface to the correct marking can be made unambiguous. The use of the set of sleeves also means that the sleeves can easily be provided with information on their outer surfaces, for example the length of the sleeve in question, the type of drill it is to be used on, the system designation,

^• etc. The threads (right-hand or left-hand threads) can be applied in such a way that the drilling direction of the tool contributes to further tightening of the

sleeve in question in the respective drill, such that unthreading during drilling is avoided.

A presently proposed embodiment of a device according to the invention will be described below with reference ^■ to the ^• attached drawings>--in which:

Figure 1 shows, in a longitudinal view and in partial cross section, a first drill type on which a number of sleeves have been symbolically indicated,

Figure 2 shows, in a side view and in partial cross section, sleeves on a second drill type,

Figures 3-6 show side views of different sleeve constructions,

Figure 7 shows a side view of a drill with applied sleeve clamped firmly between a drilling tool and an opposite surface of the drill, and

Figure 8 shows, in longitudinal section, parts of a snap-fit function for securing the sleeve in the drill.

In Figure 1, a drill is indicated by reference number 1. The drill is of the type included in the range sold by Nobel Biocare AB. The drill is a dual-purpose tool insofar as it can be used for direct formation of holes in a jaw bone, which has been indicated symbolically by reference number 2, or for formation of holes via templates 3, in which respect reference may be made to the Applicant's system ARK02. The drill is known per se and will therefore not be described in detail here, but instead only in respect of those parts which are of direct concern to the present invention. Thus, the drill comprises a drill part Ia and an attachment part Ib. The drill comprises two groups of markings 4 and 5. The markings 4 are used in connection with forming holes using said &RK system, while the markings 5 are

used for direct formation of holes in the jaw bone. In accordance with the concept of the invention, sleeves of different lengths can be applied to the drill. Each sleeve has an attachment part which, in Figure 1, is represented by reference number 6. The sleeves have

• different lengths and reach from the attachment -point on the drill down different lengths of the drill. The sleeve part 6 can also be regarded as constituting a short sleeve whose end surface 6a reaches down to the upper marking of the markings 4. The sleeve 7 has a length which exceeds the length of the sleeve 6 and reaches down to the next marking of the markings 4 with its end surface 7a. The length of the sleeve 8 exceeds the length of the sleeve 7 and its end surface 8a reaches down to the next lowest marking of the markings 4. In a corresponding manner, the sleeve 9 reaches with its end surface 9a down to the lowermost marking of the markings 4. The sleeves 7, 8 and 9 have corresponding attachment members like the sleeve 6. The attachment member in the example shown in Figure 1 consists of an internal thread 6b which cooperates with an external thread Ic on the drill. All the sleeves 6-9 can thus be screwed one at a time in the outer thread Ic on the drill. There is therefore a starting position 10 from which all the sleeves extend downward. The lengths of the sleeves can thus be varied as a function of the distance between the markings. For the sleeve 6, the length L has been indicated. The distance between the two lowermost markings has been shown by L' . In the ARK case, the bottom surface 6a, 7a, 8a or 9a of the respective sleeve cooperates with a top surface 11 of the template 3. Through the choice of sleeve 6, 7, 8 or 9, different hole depths HD can be obtained in the jaw bone 2. The lower set 5 of markings cooperates in a corresponding manner with sleeves 12, 13, 14 and 15. In the case of direct drilling, i:e. when the template arrangement ^; 3 is not present, the lower surfaces 12a, 13a, -14a and 15a cooperate with the top surface 2a of the jaw bone, cf. the function of the sleeves 6, 7, 8

and 9 and their cooperation with the template's top surface 11. The sleeves 12, 13, 14 and 15 have attachment members like those indicated for the sleeve 6. This means that the lowermost sleeves 12, 13, 14 and 15 are also provided, at their upper ends, with an -internal thread corresponding to the- thread 6b in the- sleeve 6. The sleeve set 12, 13, 14 and 15 is thus longer than the sleeve set 6, 7, 8 and 9. The different sleeves 12, 13, 14 and 15 reach down to the markings of the group 5 in the same way as the sleeves 6, 7, 8 and 9 reach down to the markings in the group of markings 4. The hole depth HD can thus be chosen, in this case too, as a function of the choice of sleeve length. The sleeves which are thus placed one at a time on the drill co-rotate with the latter. The internal and external threads Ic and 6c in this case consist of a right-hand thread, which means further tightening power upon rotation of the drill during hole formation. A first end of a sleeve 6 is indicated by reference number 6c. A drilled hole in the jaw bone is indicated by reference number 2b. A first portion of the sleeve has the reference number 6d, and a second portion of the drill has the reference number Id. The sleeves can be part of sets of sleeves sold on the open market, if appropriate together with other components, instruments and tools.

Figure 2 shows the invention when it is applied in normal drills, i.e. drills of normal length. This drill too is provided with an external thread 6b' in which corresponding inner threads Ic' in the respective sleeve 6' and 7' are screwed. In this case, only two sleeves have been indicated. The lower surface 6a' of the upper sleeve 6' reaches the upper marking of the group of markings 4' . The lower surface 7a' of the sleeve 7' reaches the subsequent marking in the group of markings 4',, etc. Said bearing surfaces 6a' and 7a' in this case come to cooperate with the top surface (cf. 2a in Figure 1) of the jaw bone or gum. This drill

too is already known and will therefore not be described in detail here. Said threads Ic' and 6b' are left-hand threads .

Figures 3 - 6 show sleeves of different lengths I/ , ^■ L'-', -L' " -and L''-". The sleeves 6'', 7" and 8" are part of the abovementioned ARK system. The sleeves have similar threads Ic by means of which each sleeve can be screwed onto the drill in accordance with the above. The sleeve according to Figure 1 belongs to the drill type according to Figure 2 and has an inner left-hand thread Ic', cf. above.

Figure 7 shows an alternative attachment function for the sleeve 16 on the drill 17. The sleeve 16 has an inner recess 16a and the drill is provided with a top surface 17a. The sleeve 16 is wedged firmly between the surface 17a and a tool/drilling tool 18 which is provided with a surface 18a lying opposite the surface 17a. If appropriate, this securing principle can be supplemented by an external thread 17b on the drill and a corresponding internal thread 16b in the sleeve.

Figure 8 shows a further embodiment in which the drill 19 is provided with a recess 19a into which a snap-fit member of the sleeve 20 can snap for the purpose of fixing the sleeve to the drill. The snap-fit member has reference number 20a.

The invention is not limited to the embodiment shown above by way of example, and instead it can be modified within the scope of the attached patent claims and the inventive concept.