DRILL BIT, DRILL KIT AND METHOD FOR DRILLING A CAVITY OR A RECESS INTO A SKULL

Abstract

A drill bit for drilling a cavity or a recess into a skull, wherein the cavity or the recess is configured to receive an implantable fixture screw unit of a hearing aid system, is disclosed. The drill bit includes a first part including a drill tip with a first drill diameter, wherein the drill tip comprises a tip angle of between 137 degrees to 143 degrees along a longitudinal axis of the drill bit and wherein the drill tip comprises a back rake angle of between −1 degree and +1 degree, in particular a back rake angle of substantially 0 degrees, a second part including a plurality of flute blades with a second drill diameter, wherein the second drill diameter is greater that the first drill diameter, and a transition part which is arranged between the first part and the second part and along the longitudinal axis, wherein the transition part includes a body clearance.

Claims

1. A drill bit for drilling a cavity or a recess into a skull, wherein the cavity or the recess is configured to receive an implantable fixture screw unit of a hearing aid system, the drill bit comprising: a first part including a drill tip with a first drill diameter, wherein the drill tip comprises a tip angle of between 137 degrees to 143 degrees along a longitudinal axis of the drill bit and wherein the drill tip comprises a back rake angle of between −1 degree and +1 degree, in particular a back rake angle of substantially 0 degrees, a second part including a plurality of flute blades with a second drill diameter, wherein the second drill diameter is greater that the first drill diameter, and a transition part which is arranged between the first part and the second part and along the longitudinal axis, wherein the transition part includes a body clearance.

2. The drill bit according to claim 1, wherein each of the plurality of flute blades of the second part comprises at least one land, and wherein the second part comprises parabolic or essentially parallel opposing surfaces extending between the lands of the plurality of flute blades.

3. The drill bit according to claim 1, wherein the plurality of flute blades comprises a cutting edge with a thickness of between 0.10 mm to 0.40 mm.

4. The drill bit according to claim 1, wherein drill flutes are arranged between the adjacent flute blades and wherein the thickness of the drill flutes varies along the drill bit and/or wherein the thickness of the drill flutes is between 0.8 mm and 1.2 mm.

5. The drill bit according to claim 1, wherein the second part or the transition part includes a back-rake angle which is either positive or negative and/or wherein the back rake angle of the flute blades is within an angle range of between −3 degrees to +3 degrees not including 0 degrees.

6. The drill bit according to claim 1, wherein the second part includes a helix angle between the longitudinal axis and a direction of the flute blades of between 20 degrees and 30 degrees, in particular a helix angle of between 24 degrees to 26 degrees.

7. The drill bit according to claim 1, wherein the transition part includes a region with an essentially constant diameter along the longitudinal axis and/or wherein a length of the region with constant diameter along the longitudinal axis is between 1.05 mm and 1.55 mm and/or wherein the region with constant diameter does not have a cutting edge.

8. The drill bit according to claim 1, wherein the body clearance includes a minimum diameter equal to a minimum diameter of the first part and a maximum diameter equal to a diameter of the second part.

9. The drill bit according to claim 1, wherein the body clearance includes a transition angle of 7 degrees to 13 degrees along the longitudinal axis and between a minimum diameter and a maximum diameter of the transition part.

10. The drill bit according to claim 1, wherein the length along the longitudinal axis and between the end of the drill tip and a maximum diameter of the transition part is between 4.65 mm and 4.75 mm.

11. The drill bit according to claim 1, wherein the drill tip has a first drill diameter of between 3.78 mm to 3.82 mm and/or wherein the drill tip comprises a cutting edge angle of between 7 degrees to 13 degrees.

12. A drill kit, comprising a drill bit according to claim 1, wherein the drill kit further comprises a guiding tool, wherein the guiding tool comprises a hollow tube, and wherein the diameter of the hollow tube is greater than the second drill diameter.

13. A method for drilling a cavity or a recess into a skull, wherein the cavity or the recess is configured to receive an implantable fixture screw unit of a hearing aid system, wherein the method comprises: applying an incision hole to a bone layer of the skull by using a first tool, cleaning the incision hole by using a cleaning tool, arranging a guiding tool into the cleaned incision hole, wherein the guiding tool includes a hollow tube, applying a drill bit into the hollow tube and drilling the cavity or the recess in a single step.

14. The method according to claim 13, wherein the drill bit comprises: a first part including a drill tip with a first drill diameter, wherein the drill tip comprises a tip angle of between 137 degrees to 143 degrees along a longitudinal axis of the drill bit and wherein the drill tip comprises a back rake angle of between −1 degree and +1 degree, in particular a back rake angle of substantially 0 degrees, a second part including a plurality of flute blades with a second drill diameter, wherein the second drill diameter is greater that the first drill diameter, and a transition part which is arranged between the first part and the second part and along the longitudinal axis, wherein the transition part includes a body clearance, and wherein the guiding tool is a guiding tool that comprises a hollow tube, and wherein the diameter of the hollow tube is greater than the second drill diameter.

15. The drill bit according to claim 2, wherein the plurality of flute blades comprises a cutting edge with a thickness of between 0.10 mm to 0.40 mm.

16. The drill bit according to claim 2, wherein drill flutes are arranged between the adjacent flute blades and wherein the thickness of the drill flutes varies along the drill bit and/or wherein the thickness of the drill flutes is between 0.8 mm and 1.2 mm.

17. The drill bit according to claim 3, wherein drill flutes are arranged between the adjacent flute blades and wherein the thickness of the drill flutes varies along the drill bit and/or wherein the thickness of the drill flutes is between 0.8 mm and 1.2 mm.

18. The drill bit according to claim 2, wherein the second part or the transition part includes a back-rake angle which is either positive or negative and/or wherein the back rake angle of the flute blades is within an angle range of between −3 degrees to +3 degrees not including 0 degrees.

19. The drill bit according to claim 3, wherein the second part or the transition part includes a back-rake angle which is either positive or negative and/or wherein the back rake angle of the flute blades is within an angle range of between −3 degrees to +3 degrees not including 0 degrees.

20. The drill bit according to claim 4, wherein the second part or the transition part includes a back-rake angle which is either positive or negative and/or wherein the back rake angle of the flute blades is within an angle range of between −3 degrees to +3 degrees not including 0 degrees.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0058] The aspects of the disclosure may be best understood from the following detailed description taken in conjunction with the accompanying figures. The figures are schematic and simplified for clarity, and they just show details to improve the understanding of the claims, while other details are left out. Throughout, the same reference numerals are used for identical or corresponding parts. The individual features of each aspect may each be combined with any or all features of the other aspects. These and other aspects, features and/or technical effect will be apparent from and elucidated with reference to the illustrations described hereinafter in which:

[0059] FIG. 1 schematically shows a perspective view of a drilling bit according to an embodiment of the disclosure;

[0060] FIG. 2 schematically shows a detail view of the embodiment shown in FIG. 1;

[0061] FIG. 3 schematically shows the cross sectional view A-A from FIG. 2;

[0062] FIG. 4 schematically shows a side view of the embodiment shown in FIG. 1;

[0063] FIG. 5A schematically shows a cavity or a recess drilled with two drill bits according to the state of the art;

[0064] FIG. 5B schematically shows a cavity or a recess drilled with one drill bit according to an embodiment of the disclosure;

[0065] FIG. 6 schematically illustrates a guiding tool according to an embodiment of the disclosure in a perspective view;

[0066] FIG. 7 schematically shows a cross sectional view of a guiding tool according to an embodiment of the disclosure;

[0067] FIG. 8 schematically shows a guiding tool according to an embodiment of the disclosure in a front view; and

[0068] FIGS. 9A-9C illustrate examples of an implantable fixture screw unit;

[0069] FIGS. 10A-10B illustrate examples of an implantable fixture screw unit; and

[0070] FIGS. 11A-11C illustrate examples of an implantable fixture screw unit and an adapter unit.

DETAILED DESCRIPTION

[0071] The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. Several aspects of the apparatus and methods are described by various blocks, functional units, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements”). Depending upon particular application, design constraints or other reasons, these elements may be implemented using electronic hardware, computer program, or any combination thereof.

[0072] Now referring to FIG. 1, which illustrates a perspective view of a drill bit 2 for drilling a cavity or a recess into a skull according to an embodiment of the disclosure. The drill bit 2 comprises a first part 4, a transition part 6 and a second part 8. The transition part 6 is arranged between the first part 4 and the second part 8. The drill bit 2 comprises a shank 10 in order to connect the drill bit 2 to a hand piece. Between the second part 8 and the shank 10 a circumferential flange 12 is arranged.

[0073] The first length of the first part 4 of the drill bit 2 is less than the second length of the second part 8 of the drill bit 2. The length (l.sub.l) along the longitudinal axis (X) and between the end of the drill tip (14) and a maximum diameter of the transition part (6) may be between 4.65 mm and 4.75 mm.

[0074] As show in FIG. 2, the first part 4 of the drill bit 2 comprises a drill tip 14 with a tip angle α of between 137 degrees and 143 degrees along a longitudinal axis X of the drill bit 2. The first part 4 of the drill bit 2 is the part of the drill bit 2 which is closest to the bone during drilling.

[0075] The first part 4 further comprises a first drill diameter d.sub.1, wherein the drill diameter d.sub.1 is bordering flanks 16 of the drill tip 14. The drill tip 14 may have a first drill diameter d.sub.1 between 3.78 mm and 3.82 mm. The second part 8 may have a second drill diameter d.sub.2, wherein the second drill diameter d.sub.2 is greater than the first drill diameter d.sub.1. By providing a drill bit 2 comprising a first drill diameter d.sub.1 and a second drill diameter d.sub.2, wherein the second drill diameter d.sub.2 is greater than the first drill diameter d.sub.1, a cavity or a recess for an implantable fixture screw unit of a hearing aid system may be drilled into the skull in one drill step. Hereby, the final osteotomy for an implant may be performed in one step.

[0076] The first part 4 of the drill bit 2 further comprises a cutting edge angle β. As shown in FIG. 3, the cutting edge angle β may be defined as an angle formed by a flank 16 of the drill tip and a plane perpendicular to the longitudinal axis X. The cutting angle may lie between 7 degrees and 13 degrees.

[0077] The drill tip 14 of the drill bit 2 comprises a back rake angle of substantially 0 degrees. The back rake angle of substantially 0 degrees leads to a sharp drill tip 14 whereby cutting forces and power requirements for the drill step may be reduced.

[0078] The transition part 6 includes a region 18 with an essentially constant diameter along the longitudinal axis X. The length l.sub.r of the region 18 is between 1.05 mm and 1.55 mm and the region 18 may not comprise a cutting edge. The transition part 6 may further comprise a body clearance 20, wherein the body clearance 20 comprises a transition angle γ of 7 degrees to 13 degrees. The transition angle γ is defined as the angle between a plane perpendicular to the longitudinal axis X of the drill bit 2 and the body clearance 20 of the transition part 6 of the drill bit 2. Aforementioned transition angle γ is beneficial for providing a cavity or a recess in a skull with one drill bit 2 in one drilling step.

[0079] FIG. 4 illustrates a side view of the embodiment shown in FIG. 1. As shown in FIG. 4, the second part 8 of the drill bit 2 comprises two flute blades 22 with the second drill diameter dz. Because of the drill diameter d.sub.2 being greater than the drill diameter d.sub.1 a cavity or a recess for an implantable fixture screw unit of a hearing aid system may be drilled into the skull in one drill step in a beneficial way.

[0080] The flute blades 22 each comprise one land 24. The land 24 may be defined as the outer portion of the body of the second part 8 bordering the flute blades 22. Between the two flute blades 22 two flutes 26 are arranged. The opposing surfaces of the flute blades 22 which extend between the lands 24 of the flute blades 22 may comprise a parabolic or an essentially parallel cross-section. The parabolic or essentially parallel surfaces of the flute blades 22 or flutes 26 lead to an improved bone chip extraction. Additionally, the total drill work of the drill bit 2 may be reduced so that an efficient removal of bone volume can be provided.

[0081] Each of the flute blades 22 comprises a cutting edge 28. The cutting edge 28 limits the flute land 24 to the cutting side of the flute blades 22. The thickness of the cutting edge 28 may lie between 0.10 mm and 0.40 mm. A cutting edge thickness in the aforementioned range is beneficial for the cutting efficiency of the drill bit 2.

[0082] The thickness of the flute blades 22 may vary along the drill bit 2, in particular along the longitudinal axis X of the drill bit 2. This allows for optimizing the thickness distribution of the drill bit 2 regarding the force and torque of the drill bit 2. The thickness of the drill flutes may be between 0.8 mm and 1.2 mm.

[0083] The second part 8 of the drill tip 2 includes a helix angle δ of between 24 degrees and 26 degrees, in particular a helix angle δ of essentially 25 degrees, between the longitudinal axis X and a plane of the flute blades 22. Said range of helix angles δ may be beneficial regarding the bone chip removal and the feed rate of the drill bit 2.

[0084] FIGS. 5A and 5B show a cavity or a recess drilled into a skull in a schematically cross-sectional view. The cavity 30 in FIG. 5A drilled is drilled by two drill bits according to the state of the art. Initially, a first drill is used in order to generate a first cavity 32. Afterwards, a widening drill is used in order to widen the first cavity or recess 32 and to drill a wider cavity 34, thus preparing the cavity or recess 30 for the implant for a bone anchored hearing aid. By using different drills, the operation surgery time is prolonged and the switching, restarting and realigning of the widening drill may cause adverse consequences for the cavity or recess to be drilled. The cavity 36 may be drilled in one step by using the drill bit 2 according to the present disclosure. Hereby, aforementioned disadvantages may be avoided.

[0085] FIG. 6 schematically illustrates a guiding tool 38 according to an embodiment of the disclosure in a perspective view. The guiding tool 38 preferably is part of a drill kit comprising the drill bit 2 and the guiding tool 38. The guiding tool 38 may protect the soft tissue during drilling, ensuring that the correct drilling depth is obtained (thus preventing too deep cavities 36) and contributing to adequate flushing. In addition, the guiding tool 38 may ensure that the cavity 36 is made perpendicular to the bone and/or skin surface.

[0086] The guiding tool 38 comprises a hollow tube 40 with an external threaded portion 42 for fixating the guiding tool 38 into the operational site by screwing the guiding tool 38 into the soft tissue. The guiding tool 38 further comprises a portion 44 with an enhanced width, wherein the portion 44 with an enhanced width may act as a mechanical stop for the at least on drilling bit 2. The portion 44 is limited by two perpendicular flanges 46 which can be used in order to manipulate the guiding tool 38.

[0087] The diameter of the hollow tube 40 may vary in order to support the drill bit 2 and to provide space for irrigation room for irrigation or for a coolant inside the hollow tube 40. FIG. 7 schematically shows a cross sectional view of a guiding tool 38 according to an embodiment of the disclosure. The guiding tool 38 has a hollow tube 40 comprising a varying inner diameter. The hollow tube 40 comprises one upper part 48 comprising a first inner diameter, one lower part 52 comprising a second inner diameter and one middle part 50 located between the upper and the lower part. The inner diameter of the middle part 50 is variable in order to connect the upper part 48 to the lower part 52. In the hollow tube 40 shown in FIG. 7, the first inner diameter of the upper part 48 is smaller than the second inner diameter of the lower part 52.

[0088] FIG. 8 schematically shows a guiding tool 38 according to an embodiment of the disclosure in a front view. The guiding tool 38 comprises a hollow channel 56 connected to the hollow tube 40 in order to provide a coolant or saline to the bottom of the osteotomy. The hollow channel 56 may be arranged essentially perpendicular to the hollow tube 40 for the drill bit 2.

[0089] FIGS. 9A, 9B and 9C schematically show an implantable fixture screw unit 60 configured to receive a bone conduction hearing aid system. The implantable fixture screw unit 60 may comprise an elongated part 62 where a first end of the elongated part is threaded 63 and configured to be anchored in the skull bone of the recipient via the drilled cavity or the recess in the skull. The elongated part 62 may comprise a second end configured to receive a skin abutment unit (64, 64A, 64B) configured to receive the bone conduction hearing aid system. The variation in skin thickness in patients is addressed by the skin abutment unit (64, 64A, 64B) of different lengths.

[0090] The skin abutment unit 60 may be attached to the elongated part by screwing (64A) it on to the elongated part or by a snap coupling (64B) where the skin abutment unit (64, 64A, 64B) is pressed on to the elongated part 62 by a movement along an axis orthogonal to the skull.

[0091] FIGS. 10A and 10B illustrate further examples of the implantable fixture screw unit 60. The implantable fixture screw unit 60 include two or more of the elongated parts (62A, 62B), where the unthreaded part of the elongated part (62A, 62B) is made of an elastic material. In FIG. 10A, the elongated part (62A, 62B) is straight, and in FIG. 10B, the elongated part (62A, 62B) is either trapeze shaped or tapered. In a further example, the two or more elongated parts may be of the same or different shape. In The diameter of the unthreaded part (62A, 62B) is smaller than a diameter of the threaded elongated part 63. The diameter of the unthreaded part (62A, 62B) of the elongated part is smaller than a diameter of the skin abutment unit (64, 64A, 64B).

[0092] The bone conduction hearing aid system may be configured to be connected to the two or more elongated parts (62A, 62B) either directly onto the skin abutment unit (64,64A,64B) or via an adapter unit 65. FIGS. 11A to 11C illustrate an example of the adapter uniter 65. The adapter unit 65 is configured to interconnect the two or more elongated parts (62A, 62B) on a first surface 67 of the adapter unit 65 and to connect to the bone conduction hearing aid system 70 on a second surface 66 of the adapter unit 65, and wherein the first surface 67 is opposite to the second surface 66, see FIG. 11B. Instead of having a skin abutment unit (64,64A,64B) connected to each of the two or more elongated parts, it would be of an advantage to interconnect the two or more elongated parts (62A, 62B) with the adapter unit 65 and without the skin abutment units being connected to the two or more elongated parts, see FIG. 11B. Thereby, the distance from the skin surface to the bone conduction hearing aid system applied onto the implantable fixture screw unit is reduced.

[0093] It is intended that the structural features of the devices described above, either in the detailed description and/or in the claims, may be combined with steps of the method, when appropriately substituted by a corresponding process.

[0094] As used, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well (i.e. to have the meaning “at least one”), unless expressly stated otherwise. It will be further understood that the terms “includes,” “comprises,” “including,” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, but an intervening element may also be present, unless expressly stated otherwise. Furthermore, “connected” or “coupled” as used herein may include wirelessly connected or coupled. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. The steps of any disclosed method are not limited to the exact order stated herein, unless expressly stated otherwise.

[0095] It should be appreciated that reference throughout this specification to “one embodiment” or “an embodiment” or “an aspect” or features included as “may” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Furthermore, the particular features, structures or characteristics may be combined as suitable in one or more embodiments of the disclosure.

[0096] The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more.

[0097] Accordingly, the scope should be judged in terms of the claims that follow.