WO2021083518A1

WO2021083518A1 - A bone drill arrangement

Info

Publication number: WO2021083518A1
Application number: PCT/EP2019/079728
Authority: WO
Inventors: Marcus Abboud
Original assignee: Marcus Abboud
Priority date: 2019-10-30
Filing date: 2019-10-30
Publication date: 2021-05-06

Abstract

The invention is directed to a bone drill arrangement (10) comprising a drill main body (20) and a separate housing sleeve (40) being attached to the drill main body (20). The drill main body (20) comprises a drill head section (22) with at least two helical land portions (301,302) defining cutting edges (321, 322) and helical flute portions (311,312) between the land portions (301, 302), and also comprises a shaft section (24) having a smaller diameter (DSL) than the drill head section (22), and comprising a coupling section (26) at the counter-coronal end. The housing sleeve (40) has an outer diameter (OSLO) being not larger than the diameter (DH) of the drill head section (22) and surrounds at least a longitudinal housed section (23) of the shaft portion (24).

Description

A bone drill arrangement

The invention refers to a bone drill arrangement for drilling a drill hole into a human bone, and in particular refers to a bone drill arrangement for drilling a drill hole into a jaw bone.

State of the art bone drills are generally made of one single piece which defines a drill head section with cutting edges, a coupling section for coupling the bone drill to a drill driving means, and a shaft section for mechanically connecting the coupling section with the drill head section. The quality of the drill hole in the human bone massively depends on the maximum temperatures within the drill hole generated during the drilling process. The lower the maximum temperature in the bone around the drill hole is, the better is the structural quality of the drill hole and the health of the surrounding bone cells for implanting an implant into the drill hole.

It is an object of the invention to provide a bone drill arrangement with a good thermal working characteristics.

This object is solved with a bone drill arrangement with the features of claim 1.

The bone drill arrangement according to the invention comprises two separate parts: a drill main body and a separate housing sleeve being attached to the drill main body. The drill main body comprises a drill head section with a drill head with at least two preferably helical land portions defining bone cutting edges and defining, seen circumferentially, preferably helical flute portions between the land portions. The drill head section has the function to remove bone material and has the function of conveying the drill waste (debris) axially away from the drill head section to the counter-coronal end of the drill main body. The drill main body comprises a coupling section at the counter-coronal end which and is provided to be releasably mountable to a drill driving means. The drill main body also comprises a shaft section having a smaller outer diameter than the outer diameter of the drill head section. The drill head section, the shaft section and the coupling section are preferebly integrally defined by one single drill main body piece being of one single material. Alternatively, the drill head section can be provided removably and exchangeable mounted to the shaft section so that the drill head can be changed.

The bone drill arrangement is provided with a separate housing sleeve having an outer diameter being not larger than the outer maximum diameter of the drill head section. The housing sleeve surrounds at least a longitudinal housed section of the shaft portion and preferably does not radially cover the drill head section. The housing sleeve preferably is a pure cylindrical sleeve and preferably is provided longitudinally between the drill head section and the coupling section of the drill main body. The separate housing sleeve has basically a thermal function. Preferably, the separate housing sleeve has no supporting function and, in particular, does not transfer any torque from the coupling section to the drill head section.

In one embodiment of the invention, the housing sleeve is made of another material than the drill main body, and more preferably is made of a material with a substantially lower thermal conductivity than the material of the drill main body. In the present context, a substantially lower thermal conductivity is at least 50% lower than the reference conductivity. Since the housing sleeve has a substantially reduced thermal conductivity, the housing sleeve is a thermal shielding which thermally isolates a substantial longitudinal section of the drill main body. As a result, the thermal energy generated in the area of the drill head section is led through the housed shaft section of the drill main body to the non- housed counter-coronal end of the drill main body. Since the temperature of the bone drill arrangement and the resulting heat radiation of the bone drill arrangement is relatively low in the housed longitudinal section, the heating of the adjacent bone hole surface is substantially reduced in this longitudinal section.

Preferably, the longitudinal length of the housing sleeve is larger than the longitudinal length of the drill head section. According to a preferred embodiment of the invention, the shaft portion has an outer diameter being smaller than the inner diameter of the housing sleeve. The shaft portion outer surface is not in touch with the inner diameter surface of the housing sleeve so that a ring space between the shaft portion and the housing sleeve is defined. The ring space is filled with air which creates a good thermal isolation of the shaft section.

Preferably, the flute portions fluidically lead into the ring space so that the drill waste is transported through the flute portions into the ring space during drilling operation. The ring space serves as a waste container or as a transport channel for the drill waste. The drill waste generally has a relative high temperature after being generated in the drill head section area. Since the housing sleeve creates a radial thermal shielding of the ring space and eliminates all friction between the surrounding bone and the removed debris, the thermal load in the drill hole is reduced significantly.

Preferably, the coronal end of the housing sleeve is provided with engagement notches engaging a corresponding structure of the drill head section to thereby define a rotational engagement structure. The rotational engagement structure allows to axially attach the coronal end of the housing sleeve to the drill head section. Preferably, the notches engage and mesh with the longitudinal ends of the flute portions. Alternatively, a screw mechanism can be provided between the sleeve and the shaft portion.

According to a preferred embodiment of the invention, the shaft section is provided with a support disc radially supporting the counter-coronal end of the housing sleeve. The support disc can be provided completely closed so that the counter-coronal end of the ring space is completely closed. In this embodiment, the ring space is a drill waste container. Alternatively, the support disc can be provided with one or more waste outlet opening so that the drill waste can continuously flow through the ring space and through the outlet opening to continuously be discharged during the drill operation.

Preferably, a locking structure is provided for axially locking the housing sleeve at the shaft section and/or at the support disc. Preferably, the locking structure is provided releasably so that the ring space can easily be cleaned and sterilized after a drilling operation. Providing the locking structure releasably also allows to choose and assemble a suitable type of housing sleeve for the following drilling application.

According to a preferred embodiment, the support disc is provided with a visible optical heat indication substance which is visible from the outside and thereby therefore is visible for the person using the bone drill arrangement. The heat indication substance can, for example, be a colour- changing substance which continuously or suddenly changes its visible colour in dependency of the temperature of the drill main body.

One embodiment of the invention is described with reference to the enclosed drawing which shows a schematic longitudinal section of a bone drill arrangement comprising a drill main body and a separate housing sleeve being releasably attached to the drill main body. According to a preferred embodiment, the housing sleeve is provided with a radial opening for allowing a cooling liquid to flow through. Preferably, the cooling liquid flows from a stationary device into the ring space, and flows from the ring space radially outwardly through the radial opening to provide a cooling effect within the drill hole.

According to another preferred embodiment, the housing sleeve is provided at the outside of the housing sleeve with a mechanical stopping means to mechanically limit the drilling depth. Preferably, the mechanical stopping means is provided as a ring line in a cross section and be provided at the outside surface of the housing sleeve.

The figure schematically shows a longitudinal section of a bone drill arrangement 10 for dental applications, in particular for drilling a drill bore into a jaw bone for applying a dental implant. The bone drill arrangement 10 comprises two separate parts: a drill main body 20 and a separate housing sleeve 40 being attached to the drill main body 20.

The drill, main body 20 comprises a drill head section 22 comprising a drill head 22' at the coronal end of the drill main body 20 and a shaft-like shaft section 24 of a substantially cylindrical form. The counter-coronal end of the drill main body 20 is provided with a coupling section 26 defined by coupling indentation for transferring high torques from a suitable drill driving means which rotates the bone drill arrangement 10.

A longitudinal middle section of the drill main body 20 and a considerable longitudinal section of the shaft section 24 define a housing section 23 where a separate housing sleeve 40 is provided. In the present embodiment, the drill head section 22 is provided with two helical land portions 301, 302 defining two cutting edges 321, 322 and also defining two helical flute portions 311, 312 between the said land portions 301, 302 (seen in circumferential direction). Generally, the constitution of the drill head section can be of any suitable kind and form which is suitable to provide a drilling action in a human bone, in particular in the jaw bone and which is suitable to transport drill waste through the helical flute portions 311, 312 in longitudinal direction away from the drill head section 22.

The hollow cylindrical housing sleeve 40 defines the housing section 23 directly adjoining the drill head section 22. The shaft section 24 is provided with a closed support disc 28 between the coupling section 26 and the housing section 23. The support disc 28 radially supports the counter-coronal end of the housing sleeve 40. The coronal end of the housing sleeve 40 is axially and radially supported by the drill head section 22 and is provided with two notches 47 engaging the two flute portions 311, 312 to thereby define a rotational engagement structure. Seen in circumferential direction, two indentations 44 are provided between the notches 47 so that the counter coronal end portions of the two land portions 301, 302 project into the indentations 44. The two flute portions 311, 312 fluidically lead the drill waste through two waste inlet openings 461, 462 into the ring space 50 defined between the shaft portion 24 and the housing sleeve 40. When the bone drill arrangement 10 is in drilling operation, the drill waste (debris) is axially transported in the counter-coronal direction through the flute portions 311,312 and through the waste inlet openings 461, 462 into the ring space 50 where the drill waste remains until it is removed after the drilling operation.

Two releasable locking structures 481, 482 are provided at the inside of the counter-coronal end of the housing sleeve 40 for axially locking the housing sleeve 40 at the support disc 28. The locking structures 481, 482 are realized, in this embodiment, as spring locking members. Generally, the locking structures can be of any suitable kind and form.

The drill main body 20 is, in the present embodiment, made of a body material 20' of medical stainless steel which is suitable to define hard helical land portions 301, 302 and cutting edges 321, 322. The housing sleeve 40 is defined by a housing sleeve body 42 made of zirconia. Zirconia has a substantially lower thermal conductivity than the medical stainless steel of the drill main body so that the housing sleeve 40 thermally isolates the ring space 50 to the outside. However, the housing sleeve body 42 can alternatively, made of any other suitable material, such as plastic, in particular PEEK, or a ceramic material.

The maximum outer diameter DH of the drill head section 22 is, in the present embodiment, 4,0 mm, the outer diameter DSLO of the housing sleeve 40 is 3,9 mm, the inner diameter DSLI of the housing sleeve 40 is 3,5 mm, and the outer diameter DSH of the shaft body 20 is about 2,0 mm. The support disc 28 is provided at the cylindrical outside surface with a visible optical heat indication substance 29 which is not covered by the housing sleeve 40 and therefore is visible from the outside. The heat indication substance 29 indicates by its colour the temperature of the drill main body 20.

The housing sleeve 40 is provided with a mechanical stopping means 70 to limit the drilling depth. The stopping means 70 is provided as a closed ring provided at the outside surface of the housing sleeve body 42. The housing sleeve 40 is also provided with two or more radial openings 72 for allowing a cooling liquid to flow through. The cooling liquid is pumped by a stationary device into the ring space 50 from where the cooling liquid flows radially outwardly through the radial openings 72 to cool the dill hole wall.

Claims

CLAIMS 1. A bone drill arrangement (10) comprising a drill main body (20) and a separate housing sleeve (40) being attached to the drill main body (20), wherein the drill main body (20) comprises a drill head section (22) with at least two land portions (301,302) defining cutting edges (321, 322) and flute portions (311, 312) between the land portions (301, 302), comprises a shaft section (24) having a smaller diameter (DSL) than the drill head section (22), and comprising a coupling section (26) at the counter-coronal end, and the housing sleeve (40) having an outer diameter (DSLO) being not larger than the diameter (DH) of the drill head section (22) surrounds at least a longitudinal housed section (23) of the shaft portion (24).

2. The bone drill arrangement (10) of claim 1, wherein the shaft portion (24) has a diameter (DSH) being smaller than the inner diameter (DSLI) of the housing sleeve (40), the housing sleeve (40) defining a ring space (50) between the shaft portion (24) and the housing sleeve (40).

3. The bone drill arrangement (10) of claim 2, wherein the flute portions (311, 312) fluidically lead into the ring space (50) so that the drill waste is transported through the flute portions (311, 312) into the ring space (50) during drilling operation.

4. The bone drill arrangement (10) of one of the preceding claims, wherein the housing sleeve (40) is made of another material than the drill main body (20), preferably of a material with a substantially lower thermal conductivity than the material of the supporting main body (20).

5. The bone drill arrangement (10) of one of the preceding claims, wherein the coronal end of the housing sleeve (40) is provided with notches (47) engaging a corresponding structure of the drill head section (22) to define a rotational engagement structure.

6. The bone drill arrangement (10) of one of the preceding claims, wherein the shaft section (24) is provided with a support disc (28) radially supporting the counter-coronal end of the housing sleeve (40).

7. The bone drill arrangement (10) of one of the preceding claims, wherein a locking structure (481,482) is provided for axially locking the housing sleeve (40) at the shaft section (24).

8. The bone drill arrangement (10) of one of the preceding claims 6 or 7, wherein the support disc (28) is provided with a visible optical heat indication substance (29).

9. The bone drill arrangement (10) of one of the preceding claims, wherein the longitudinal length of the housing sleeve (40) is larger than the longitudinal length of the drill head section (22).

10. The bone drill arrangement (10) of one of the preceding claims, wherein the housing sleeve (40) is provided with a radial opening (72) for allowing a cooling liquid to flow through.

11. The bone drill arrangement (10) of one of the preceding claims, wherein the housing sleeve (40) is provided with a mechanical stopping means (70) to mechanically limit the drilling depth.