The present invention relates to an arrangement used on a drill template oriented in the mouth for forming holes intended to extend from the template and into the zygoma. The template in this case comprises one or more guide sleeves which define the direction toward the zygoma .

The structure and orientation of the drill template is dealt with in a parallel application which was submitted on the same day as the present application and by the same applicant. The drill template is produced, inter alia, by means of computer-aided equipment in a manner known per se.

Various guide arrangements for guiding drills are already known in ^■ dentistry. When forming holes for implants and screws which are to extend into and be anchored in the zygoma, special problems arise on account of the precision requirements that have to be met in terms of the hole direction. Incorrect handling and incorrect equipment can mean deviations from the drill direction defined with precision in the computer- aided equipment, which means there is a high risk of the drill direction being wrong and of the drill penetrating through sensitive parts of the eye or orbital cavity.

The present invention aims to solve these problems among others. It is also important that, despite the aforementioned precision, the arrangement for hole formation can be highly flexible and that components known per se can be used. The invention also deals with this problem.

What can principally be regarded as characterizing an arrangement according to the invention is that one or

"more first cylindrical extension units which determine

the hole direction can be applied in a respective guide sleeve. One or more first drills with one or more first diameters can be directed by means of the respective extension unit toward the jaw bone and/or zygoma in said direction for forming an introductory hole extent with a respective first diameter. Finally, the invention is characterized in that one or more drill guide units for one or more second drills with one or more second diameters can be inserted toward the bottom of the introductory hole extent for continued drilling.

In further developments of the inventive concept, the first cylindrical extension units are formed as cylinders with longitudinal and continuous central holes. The extension units can be two in number and can have different diameters for the holes. The drill guide units can be designed with cylindrical portions which have external diameters corresponding to the internal diameters in the • respective guide sleeve and/or extension unit. The drill guide units can be designed with handle parts which mean that they are easy to maneuver by hand. First drill guide units can be arranged to support second drill guide units in the same way as they themselves are supported in the guide sleeves. Further developments of the inventive concept are set forth in the attached dependent claims.

By means of the above, it is entirely possible to achieve an efficient arrangement in which said risks of damage can be effectively avoided, since there is a very close connection to the hole direction that was predicted in the computer-aided equipment.

A presently proposed embodiment of an arrangement having the features characteristic of the invention will be described below with reference to the attached drawings, in which:

Figure 1 shows, in a perspective view from underneath, an example of a drill template which has been produced in computer-aided equipment and which has been assigned an orientation in the patient' s ^' mouth,

Figure 2 is a vertical view showing the configuration of a first extension unit,

Figure 3 is a vertical view showing an illustrative embodiment of a second vertical unit,

Figure 4 is a side view showing examples of drills with first diameters,

Figure 5 is a vertical view showing conventional drills that can be used in forming holes,

Figure 6 is a side view, in slight perspective, of first drill guide units that can cooperate with guide sleeves in the drill template according to Figure 1,

Figure 7 is a perspective view, obliquely from underneath, of second configurations of drill guide units that can be applied in guide sleeves of the drill template and/or in the units according to Figures 2 or 3,

Figure 8 is a vertical section showing application of a drill guide unit in a unit applied in a guide sleeve in the drill template,

Figure 9 is a vertical view showing a first drill guide unit arranged in the guide sleeve in the drill template, and a second guide unit that can be applied to the guide sleeve applied in the guide sleeve,

Figure 10 is a vertical section showing the application of an extension unit to a guide sleeve in the drill template,

Figure 11 is a vertical section showing the principle of application of a drill template to the zygoma and the application of an extension unit in the guide sleeve, and also a drill with a first diameter, by means of which an introductory hole extent can be formed, and

Figure 12 is a vertical section showing a drill guide unit applied in the guide sleeve of the drill template and guiding a drill down to the bottom of said introductory hole extent for formation of a hole through the zygoma.

In Figure 1, a drill template is indicated by 1. The drill template has guide sleeves 2, 3 which are applied with the aid of computer-aided equipment (not shown) . The longitudinal axes of the guide sleeves, see longitudinal axis 2a for guide sleeve 2, are directed toward a solid part of a symbolically indicated zygoma 4. In the present case, the template has two guide sleeves which are directed toward said zygoma part 4 on one side of the zygoma. A corresponding arrangement with two guide sleeves can be present for alignment with the other side of the zygoma.

Figure 2 shows a cylindrical extension unit 5 from the side. The cylindrical unit has an external diameter D and an internal diameter d and is thus provided with an internal central hole (not shown in Figure 2) extending in the longitudinal direction of the cylinder. The unit 5 has a length L. In the illustrative embodiment, the length can be ca. 30 mm. The diameter D is ca. 6 mm, and the internal diameter d is ca. 4 mm. Said unit can be applied to the respective guide sleeve 2, 3 which has an internal diameter slightly greater than the

diameter D, i.e. the extension unit can be inserted into the guide sleeve. ^•

Figure 3 shows an extension unit with in principle the same structure as the unit 5 in Figure 2. The unit 6 has a structure corresponding to the unit 5 but has different dimensions. In one illustrative embodiment, the unit 6 can be applied in the sleeve 2 or 3 and can receive the sleeve 5 in its longitudinal and continuous central recess. Alternatively, the units 5 and 6 are exchangeable in said sleeve 2 or 3.

Figure 4 shows two drills 7, 8 known per se. The drill 7 can have a smaller external diameter than the drill 8 and can cooperate with the unit 5 according to Figure 2, while the drill 8 can cooperate with the unit 6 according to Figure 3.

Figure 5 shows two conventional drills 9 and 10, the drill 9 having a diameter of 2.9 mm and the drill 10 having a diameter of 3.5 mm. These drill diameters are substantially less than the drill diameters of the drills 7 and 8 according to Figure 4.

Figure 6 shows drill guide units 11 and 12 with cylinder parts 11a and 12a via which the drill guide units can be applied in either the units 5, 6 or, in an alternative embodiment, directly in the guide sleeve 2 in the drill template. The units 11 and 12 also comprise handle parts lib and 12b by means of which the units can be applied in the central hole in question and which allow the units to be turned about the longitudinal axes of the parts 11a and 12a.

Figure 7 shows second drill guide units 13, 14, 15 with a corresponding structure to that of the drill guide units 11 and 12, but with different dimensions. In one illustrative embodiment, the units 13, 14 and 15 can be applied directly to the guide sleeve (e.g. 2) in the

drill template. It is also conceivable to arrange these guide units so that they can be applied to the extension units 5 and β. In one embodiment, the control units 13, 14, 15 can also receive the guide units 11 and 12 via their longitudinal central holes.

Figure 8 shows the guide sleeve 2 according to Figure 1 in diagrammatic form. An extension unit, for example the extension unit 5, is applied in the guide sleeve. Thereafter, a guide unit 11 (cf. Figure 6) can be inserted in the continuous central hole 5a of the extension unit into the recess 5a via its guide part 11a. The unit 11 is provided with a longitudinal continuous recess lie for a drill according to Figure 5.

Figure 9 shows another embodiment in which the unit 13 according to Figure 7 is inserted into the guide sleeve 2 in the drill template according to Figure 1 and the unit 11 is in turn inserted in the central hole of the unit 13. It should be noted here that the guiding between the different components (the sleeve parts) is considerable and that the gap between two respective units is of the order of magnitude of 0.1 mm.

Figure 10 shows, in a diagrammatic representation, the insertion of the unit 6 in the direction of arrow 14 into the sleeve 2 in the drill template.

Figure 11 shows a hole being formed in connection with the sleeve 2 in the template 1 where the extension unit 5 is applied in the guide sleeve. The unit 5 guides a drill 7 (or 8) via its longitudinal central hole 5a. By means of the drill, an introductory hole extent is formed in the solid part of the zygoma 4. The introductory extent has the length A and can be varied from case to case. The drill is driven by mechanical equipment (electric motor) 15 of a type known per se and in a manner known per se. The equipment 15 rotates

the drill about its longitudinal axis 16, for example in the drilling direction 17.

Figure 12 is intended to show the stage where the hole formation is completed following the state shown in Figure 11. The extension unit 5 has been replaced here by the drill guide unit 13 (see Figure 7) which assumes the position shown in Figure 12 in the guide sleeve 2 of the drill template 1. In this case, the drill 9 according to Figure 5 is used, which drill can thus be guided by the unit 13 and move to the bottom 18 of the hole 19 formed by the drill 7. The end of the drilled hole 19 is cone-shaped and the drill 9 in this way acquires a locating function. In Figure 12, the continuation of the hole formed with the drill 9 is indicated by broken lines 20. In the present case, the drill has been allowed to penetrate slightly out of the zygoma 4, with the result that the drill can be felt by the fingers through the patient's skin 22 outside the zygoma.

It will be appreciated that the drill hole formation can be carried out in stages with different drills of different diameters. Thus, the hole 19 can be started with the drill 17 according to Figure 4 and completed with the drill 8 according to Figure 4. Correspondingly, the drills 9 and 10 with the different diameters can be used for forming the hole 20. It will also be appreciated that different configurations and dimensions can be used on the drill guide units 11-15. The hole parts 19 and 20 formed can subsequently be threaded with a thread tap (not shown) in a manner known per se. In Figure 12, the drive equipment for the drill 9 is indicated by 23, which drive equipment can be of the same type as the drive equipment 15 and for example can comprise a drill machine, screwdriver, etc. The longitudinal axis is indicated by 24 in the case according to Figure 12, while the direction of rotation is indicated by 25.

In accordance with -the inventive concept, the drill guides 10, 11 according to Figure 6 can be used on an instrument (not shown) by means of which it is possible to indicate and mark out on the patient's skin outside the zygoma the drill end of the drill which is used for forming the hole 20. Said instrument is described in more detail in an application submitted on the same day as the present application and by the same Applicant as for the present patent application. Said instrument is designed with a sleeve-shaped fastening or anchoring part which can extend in the guide sleeve in the drill template. Each of said units 10, 11 can thus be inserted by way of its cylindrical part into the sleeve of the instrument and the precision or play between the parts is of the same order of magnitude as has been described above.

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