Dental screwdriver with a flexible shaft and method for manufacturing a dental screwdriver

Abstract

For the purpose of increased flexibility and ease of use of a dental screwdriver (1) designed to connect an abutment screw (55) of a suprastructure abutment to a dental implant, and which has a shaft (15) having a proximal end (10) with a handle (5) and a distal end (20), the shaft (15) is designed to be flexible. A method for manufacturing a dental screwdriver (1) provides that its shank (15) is thermally and / or mechanically treated, and / or that its shank (15) is provided with at least one taper (30, 35), and / or that at least one section of the shank (15) located away from the proximal end (10) and / or the distal end (20) is subjected to mechanical treatment such that the strength of the section is greater than the strength of the shank (15) in the region of the proximal end (10) and / or the distal end (20).

Description

The present invention relates to a dental screwdriver according to claim 1 and a method for manufacturing a dental screwdriver according to claim 9. Current dental implants consist of an implant, a superstructure abutment, and a superstructure: The implant is typically screw-shaped and is inserted into the jawbone, where it integrates with the bone. After the required healing period, a superstructure abutment is attached to the implant, to which a superstructure, usually an implant crown, is then attached. The superstructure abutment is secured by an abutment screw, which is inserted through a screw channel in the superstructure and tightened onto the implant using a dental screwdriver. After assembly, the screw channel is filled with a filling material. For the purpose of fastening the superstructure abutment, a dental screwdriver is used, which extends through the screw channel, exerts sufficient torque on the abutment screw, and is removed from the screw channel after the abutment screw has been fastened. A corresponding system using a dental screwdriver is known from EP 3 041 434 B1. This document shows the use of a dental screwdriver for fastening an abutment screw, but does not provide any information regarding the design of the dental screwdriver itself. A design for a dental screwdriver is known from DE 20 2007 019 557 U1 and DE 20 2007 019 558 U1. The dental screwdriver shown therein is designed to connect an abutment screw of a suprastructure abutment to a dental implant. It has a shaft with a proximal end and a distal end, the proximal end having a handle. The shaft consists of a multitude of twisted wires or wires twisted around a core. This design is disadvantageously complex and expensive, requires a relatively large amount of space during use, and is not always easy to handle with regard to complying with necessary sterilization requirements. From US Patent 2023 / 0414321 A1, a dental screwdriver is known that is designed to connect an abutment screw of a suprastructure abutment to a dental implant. The screwdriver has a shaft with a proximal end and a distal end, the proximal end of which has a handle. The shaft is flexible and has an abutment screw at its distal end, which is designed to connect the suprastructure abutment to the dental implant. However, removing the dental screwdriver from the screw channel after the fastening process is complete is not easily possible, which is a disadvantage. The object of the present invention is to provide a dental screwdriver that overcomes the aforementioned disadvantages. This problem is solved by a dental screwdriver having the features of claim 1. Advantageous embodiments of the present invention are specified in the dependent claims. The task is thus accomplished by a dental screwdriver designed to connect an abutment screw of a suprastructure abutment to a dental implant, and which has a shaft with a proximal and a distal end. A handle is located at the proximal end. At the distal end, the shaft is designed to apply torque to the abutment screw. The distal end has an outer surface designed to engage with a tool in a force-fit and / or form-fit manner. The dental screwdriver features a flexible shaft. This allows for reliable torque transmission from the handle to the abutment screw, not only in straight screw channels but also, and particularly advantageously, in curved screw channels, as the screwdriver can both follow the curve of the screw channel and transmit torque while positioned within it. The dental screwdriver's advantages are especially evident when working with implants located in the upper anterior region. Alternatively or cumulatively, the shaft is solid, i.e., made from a single piece. Alternatively or cumulatively, the shaft is at least partially hollow. The aforementioned advantages apply accordingly. It is understood that the dental screwdriver must be removed from the screw channel after the fastening process is complete. According to the invention, the shaft is designed to be detachable from the abutment screw head, with the separation of the shaft and abutment screw head occurring in such a way that, after completion of the fastening process, the former is twisted off or shears off due to a further increase in the applied torque. In this respect, the connection point between the shaft and the abutment screw head forms a predetermined breaking point. In principle, the shaft of the dental screwdriver according to the invention can be made of any suitable material. It is advantageously possible, for example, to make the shaft, and particularly advantageously also part or all other components of the dental screwdriver according to the invention, from an iron-containing alloy. The iron-containing alloy preferably has the following composition: 15 to 20 wt.% chromium, 5 to 14 wt.% nickel, up to 2.5 wt.% silicon, up to 1 wt.% molybdenum, 0.04 to 0.17 wt.% carbon, up to 0.13 wt.% nickel, up to 0.05 wt.% phosphorus, up to 0.017 wt.% sulfur, and iron such that the sum of all components is 100 wt.%. In a particularly preferred manner, the iron-containing alloy has the following composition: 16 to 21 wt.% chromium, 7 to 13 wt.% nickel, 0.07 to 0.16 wt.% carbon and iron such that the sum of all components is 100 wt.%. In a further preferred embodiment, the iron-containing alloy has the following composition: 35 to 45 wt.% cobalt, 15 to 25 wt.% chromium, 14 to 18 wt.% nickel, 12 to 16 wt.% iron, 6 to 8 wt.% molybdenum, 1 to 3 wt.% manganese and silicon such that the sum of all components is 100 wt.%. In a particularly preferred manner, the iron-containing alloy has the following composition: 40 wt.% cobalt, 20 wt.% chromium, 16 wt.% nickel, 14 wt.% iron, 7.25 wt.% molybdenum, 2 wt.% manganese and silicon such that the sum of all components is 100 wt.%. According to a preferred embodiment, the dental screwdriver according to the invention is characterized in that the shank, and in a particularly advantageous manner also a part or all other components of the dental screwdriver according to the invention, is made at least partially of Nitinol. In other words, the shank is made at least partially of an alloy consisting of 55 wt.% to 56 wt.% nickel and 44 wt.% to 45 wt.% titanium, which together make up 100 wt.%. It should be noted that the shank need not only be made partially of Nitinol; rather, it is particularly advantageous if it is made entirely of Nitinol. Due to the inventive, at least partial construction of the shaft from Nitinol, simple and therefore cost-effective manufacturing of the dental screwdriver according to the invention is possible. Advantageously, a material alloy is provided that has already proven itself in medical practice. This is all the more true when the entire shaft is made of Nitinol. Furthermore, this can reduce the time required for inserting the dental screwdriver according to the invention into the screw channel located in the superstructure, the time required for the screwing process itself, and the time required for removing the dental screwdriver according to the invention after completion of the screwing process, which advantageously results in greater comfort for and less physical and mental strain for patients, surgeons, dentists, and those assisting them during the assembly of the superstructure abutment on the implant. The handle provided on the dental screwdriver according to the invention can be designed in any suitable way. Advantageously, it has a contour, particularly preferably a star-shaped contour, which is designed to be operatively connected to a tool, in particular a torque wrench. In other words, the handle is designed such that a force or torque exerted by a tool, in particular a manual one, can be transmitted to the shaft of the dental screwdriver according to the invention in order to align the shaft in the screw channel along its longitudinal axis following the contour of the possibly curved screw channel, and to rotate it in order to exert a torque on the abutment screw. The handle can, in particular, be made of a plastic material. The handle can be connected to the shaft in any suitable manner. In particular, it is possible to make the handle from the same material as the shaft. Thus, if the shaft is made of an iron-containing alloy, the handle is advantageously made of the same iron-containing alloy. Conversely, if the shaft is made of nitinol, the handle is advantageously made of the same nitinol. In the aforementioned cases, the handle and shaft can advantageously be formed as a single piece. Alternatively, the handle and shaft can be permanently or detachably connected. Advantageously, the handle and shaft can be bonded, joined by microplasma welding, or joined by laser micro-welding. Furthermore, the handle can be attached to the shaft by either snapping it on or shrinking it onto the shaft. A connection between the distal end of the shaft and the abutment screw is advantageously achieved by the former being designed to engage with a functionally interlocking part of the abutment screw in a force-fit and / or form-fit manner. The end of the shaft can thus be designed, in particular, as a slot, triangular, square, hexagonal, or six-lobed shape, which engages in a corresponding receptacle of the abutment screw—that is, a projection engaging in the slot, an internal triangular, an internal square, an internal hexagon, or an internal six-lobed shape—during the insertion of the abutment screw into the implant. The distal end of the shaft, in particular as a square, hexagon, or six-round shape, can be formed in any suitable manner. For example, the distal end of the shaft can be made of the same material as the shaft itself. Thus, if the shaft is made of an iron-containing alloy, the distal end of the shaft is advantageously made of the same iron-containing alloy. If, on the other hand, the shaft is made of nitinol, the distal end of the shaft is advantageously made of the same nitinol. In the aforementioned cases, the distal end of the shaft and the shaft itself can advantageously be formed as a single piece. Alternatively, a separate section can be provided at the distal end of the shaft, featuring a design corresponding to the abutment screw, in particular a square, hexagonal, or six-round head, and connected to the shaft. Here too, the distal end of the shaft and the shaft itself can be made of the same material. Overall, the dental screwdriver according to the invention is a product which, compared to some dental screwdrivers known from the prior art, is in particular: - more articulated, - requires less space, - more flexible in radius, - less complex in design, - significantly lighter and therefore more environmentally friendly and cost-effective to manufacture, - easier to sterilize, and - user-friendly, efficient and precise. In principle, the shaft can have any suitable cross-sectional shape. In particular, it can have a round or hexagonal cross-section. Furthermore, the shaft can be straight in its longitudinal direction, i.e., with a constant cross-sectional shape. According to a preferred embodiment, the shaft, viewed in its longitudinal direction, has a non-constant cross-section, in particular a variable diameter or hexagonal cross-section. Thus, the shaft, viewed in its longitudinal direction, can have a variable cross-section, at least one shoulder, and / or at least one recess. This advantageously makes it even easier to achieve the desired deformation of the shaft within the screw channel. This is especially true if the shaft of the dental screwdriver according to the invention has a first taper in its region adjacent to the proximal end and / or a second taper in its region adjacent to the distal end. This advantageously further increases the flexibility of the dental screwdriver according to the invention, particularly if its shaft is made of an iron-containing alloy of the type disclosed above. Thus, a first taper is located at the proximal end of the shaft, allowing for precise adaptation of the shaft to the curvature of the screw channel during the rotational movements required to secure the abutment screw. Alternatively, or cumulatively, a second taper is located at the distal end of the shaft. This second taper improves the shaft's adaptation to the curvature of the screw channel during the rotational movements required to secure the abutment screw, and facilitates screwdriver interaction in the spatially limited working area. Overall, both tapers, whether used individually or in combination, thus facilitate deformation of the shaft within a curved screw channel. It should be noted that a taper can also be provided at a different section. For example, the taper can be located on a shaft segment that is farther from the proximal or distal end. It is also possible to provide more than one taper on this shaft segment. In principle, dental screwdrivers and abutment screws can each be two different components, as is known from the prior art. Therefore, the dental screwdriver according to the invention and the abutment screw to be fastened by it can also be different components, whereby the advantages relating to the disclosed dental screwdriver, and in particular its shank, cannot be achieved with the dental screwdriver known from the prior art. According to a preferred embodiment, the shaft of the dental screwdriver according to the invention now has an abutment screw at its proximal end, which is configured to connect the superstructure abutment to the dental implant. In other words, the abutment screw required for securing the superstructure abutment is not a separate component from the dental screwdriver, but rather a component connected to it, which, together with the shaft, is inserted into the screw channel for the purpose of securing the superstructure abutment. This further reduces the time required to secure the superstructure abutment to the implant, which is accompanied by the advantages for patients, surgeons, dentists, and their support personnel already described above. According to a preferred embodiment, the abutment screw connected to the dental screwdriver has an abutment screw head located at one end of the shaft. At the other end, an abutment screw cone tapers in the direction away from the shaft. A shaft is connected to the abutment screw cone, and the shaft has an abutment screw thread at its distal end. In principle, the design, particularly the geometric design, of the abutment screw head, the abutment screw cone, the abutment screw shank, and / or the abutment screw thread can correspond to designs known from the prior art for abutment screws. However, this is not mandatory. Rather, it may be possible to design the abutment screw thread according to the invention in accordance with abutment screw threads known from the prior art, particularly with regard to its thread type, profile shape, and / or pitch, in order to achieve compatibility with existing dental implantation systems, while another part or all other parts of the abutment screw do not correspond to those parts of known abutment screws. The shank of the dental screwdriver according to the invention can be connected to the abutment screw in any suitable manner. Preferably, the shank and the abutment screw are formed in one piece. Alternatively, it is possible to fasten the abutment screw head and the distal end of the shank together, in particular by gluing, soldering, or welding. Alternatively, a recess can be provided in the abutment screw head in which the corresponding end of the shank is received in a form-fitting or material-locking manner. In a particularly advantageous embodiment, the abutment screw head has a recess that corresponds to a recess of already known abutment screws, while the shank has a corresponding surface in this area. Thus, the end of the shank can be, in particular,The abutment screw head must be designed as a hexagon or a six-sided rounded shape, engaging with a corresponding recess in the screw head. The elements mentioned above must be connected to one another, in particular by bonding, positive locking, force locking, or other material bonding. In this case, compatibility with existing dental implant systems is achieved. As already mentioned, in a preferred embodiment the shaft and the abutment screw are formed in one piece. In other words, the previously disclosed two-part, but functionally connected, design of shaft and abutment screw head is eliminated in favor of a one-piece design of shaft and abutment screw, thereby advantageously simplifying the manufacture of a dental screwdriver equipped with an abutment screw. It is also understood that the handle of the dental screwdriver must be removed after the fastening process is complete. This can advantageously be achieved by grinding the handle off the shaft. Alternatively, according to the invention, the handle is designed to be detachable from the shaft. In a particularly preferred manner, the separation of the shaft and handle occurs such that, after completion of the fastening process, the former is twisted off or breaks off by a further increase in the applied torque. In this respect, the connection point between the shaft and the abutment screw head forms a predetermined breaking point. According to a preferred embodiment of the dental screwdriver according to the invention, a predetermined breaking point can be provided on the shaft. The predetermined breaking point is designed, in particular positioned and dimensioned, such that after completion of the fastening process of the abutment screw in the implant, the shaft is twisted or breaks off due to a further increase in the applied torque. Any resulting remnant of the shaft can remain in the screw channel, since it is made of a biocompatible material and is already enclosed by a filling material that fills the screw channel. Should it ever become necessary to loosen the abutment screw, mounted according to the preceding paragraph, from the superstructure abutment and remove it from the screw channel, a preferred embodiment provides that the shaft has an outer surface on at least one section, which is designed to engage with a tool in a force-fit and / or form-fit manner. In other words, the invention provides that—especially after removal of the filling material—a tool engages the portion of the shaft remaining in the screw channel, so that it can be unscrewed from the superstructure abutment together with the abutment screw to which it remains connected. Advantageously, the outer surface has a square, hexagonal, or hexagonal cross-section. The removal of the filling material itself is carried out, as is known per se, by means of a hole-saw-like tool. For this purpose, the corresponding section of the shaft is advantageously designed as a threaded section. Thus, this section of the shaft remaining in the screw channel forms an external threaded section on which the tool for removing the abutment screw can engage. In the event that a previously disclosed external and / or internal thread is indeed provided, this thread of the threaded section is, according to a preferred embodiment, designed as a thread running counter to the thread of the abutment screw. Thus, if the thread of the abutment screw is a right-hand thread, the threaded section of the shank is a left-hand thread. Conversely, if the thread of the abutment screw is a left-hand thread, the threaded section of the shank is a right-hand thread. This allows the abutment screw to be advantageously and safely removed by means of the shank remaining in the screw channel, using the tool. To solve the aforementioned problem underlying the invention, a method is also described for manufacturing the dental screwdriver according to the invention. The method comprises the following steps: a) providing a shaft having a proximal end and a distal end, wherein the proximal end is configured to have a handle and / or the distal end is configured to have an outer surface configured to engage with a tool in a force-fit and / or form-fit manner, or the distal end is configured to have an abutment screw;and b) performing a thermal and / or mechanical treatment of the shaft on at least one shaft section located between the proximal end and the distal end, and / or c) introducing a first taper in a shaft section adjacent to the proximal end of the shaft and / or introducing a second taper in a region adjacent to the distal end of the shaft, and / or d) performing a mechanical treatment on at least one section of the shaft located away from the proximal end and / or the distal end such that the strength of the section is greater than the strength of the shaft in the region of the proximal end and / or the distal end. According to the disclosure of the invention, thermal treatment means any suitable form of heat treatment in accordance with the standard DIN 8580:2022-12. According to a preferred embodiment, the mechanical treatment of the shaft section includes polishing and / or cold forming. Therefore, in a first preferred embodiment, the method according to the invention comprises the following steps: a) providing a shaft having a proximal end and a distal end, wherein the shaft is not made of nitinol and wherein the proximal end is provided to have a handle and / or the distal end is provided to have an outer surface which is provided to cooperate with a tool in a force-fit and / or form-fit manner, or the distal end is provided to have an abutment screw; and b) performing a thermal treatment of the shaft on at least one shaft section located between the proximal end and the distal end. In this case, the shaft consists in particular of one of the previously disclosed iron-containing alloys. Alternatively, in a second preferred embodiment, the method according to the invention comprises the following steps: a) providing a shaft having a proximal end and a distal end, wherein the shaft is made of nitinol and wherein the proximal end is configured to have a handle and / or the distal end is configured to have an outer surface configured to interact with a tool in a force-fit and / or form-fit manner, or the distal end is configured to have an abutment screw; and b) performing a thermal treatment of the shaft on at least one shaft section located between the proximal end and the distal end. In this case, the shaft consists in particular of the previously disclosed nitinol. Alternatively, in a third preferred embodiment, the method according to the invention comprises the following steps: a) providing a shaft having a proximal end and a distal end, wherein the shaft is not made of nitinol and wherein the proximal end is provided to have a handle and / or the distal end is provided to have an outer surface that is provided to cooperate with a tool in a force-fit and / or form-fit manner, or the distal end is provided to have an abutment screw; and b) introducing a first taper in a shaft section adjacent to the proximal end of the shaft and / or introducing a second taper in a region adjacent to the distal end of the shaft. In this case, the shaft consists in particular of one of the previously disclosed iron-containing alloys. Alternatively, in a fourth preferred embodiment, the method according to the invention comprises the following steps: a) providing a shaft having a proximal end and a distal end, wherein the shaft is made of nitinol and wherein the proximal end is configured to have a handle and / or the distal end is configured to have an outer surface configured to engage with a tool in a force-fit and / or form-fit manner, or the distal end is configured to have an abutment screw; and b) introducing a first taper in a shaft section adjacent to the proximal end of the shaft and / or introducing a second taper in a region adjacent to the distal end of the shaft. In this case, the shaft consists in particular of the previously disclosed nitinol. Alternatively, in a fifth preferred embodiment, the method according to the invention comprises the following steps: a) providing a shaft having a proximal end and a distal end, wherein the shaft is not made of nitinol and wherein the proximal end is configured to have a handle and / or the distal end is configured to have an outer surface configured to engage with a tool in a force-fit and / or form-fit manner, or the distal end is configured to have an abutment screw; and b) performing a mechanical treatment on at least one section of the shaft located away from the proximal end and / or the distal end such that the strength of the section is greater than the strength of the shaft in the region of the proximal end and / or the distal end. In this case, the shaft consists in particular of one of the previously disclosed iron-containing alloys. Alternatively, in a sixth preferred embodiment, the method according to the invention comprises the following steps: a) providing a shaft having a proximal end and a distal end, wherein the shaft is made of nitinol and wherein the proximal end is configured to have a handle and / or the distal end is configured to have an outer surface configured to engage with a tool in a force-fit and / or form-fit manner, or the distal end is configured to have an abutment screw; and b) performing a mechanical treatment on at least one section of the shaft located away from the proximal end and / or the distal end such that the strength of the section is greater than the strength of the shaft in the region of the proximal end and / or the distal end. In this case, the shaft consists in particular of the previously disclosed nitinol. Alternatively, in a seventh preferred embodiment, the method according to the invention comprises the following steps: a) providing a shaft having a proximal end and a distal end, wherein the shaft is not made of nitinol and wherein the proximal end is configured to have a handle and / or the distal end is configured to have an outer surface configured to engage with a tool in a force-fit and / or form-fit manner, or the distal end is configured to have an abutment screw; and b) performing a thermal treatment of the shaft on at least one shaft section located between the proximal end and the distal end, and c) introducing a first taper in a shaft section adjacent to the proximal end of the shaft and / or introducing a second taper in a region adjacent to the distal end of the shaft. In this case, the shaft consists in particular of one of the previously disclosed iron-containing alloys. Alternatively, in an eighth preferred embodiment, the method according to the invention comprises the following steps: a) providing a shaft having a proximal end and a distal end, wherein the shaft is made of nitinol and wherein the proximal end is configured to have a handle and / or the distal end is configured to have an outer surface configured to interact with a tool in a force-fit and / or form-fit manner, or the distal end is configured to have an abutment screw; and b) performing a thermal and / or a mechanical treatment of the shaft on at least one shaft section located between the proximal end and the distal end, and c) introducing a first taper in a shaft section adjacent to the proximal end of the shaft and / or introducing a second taper in a region adjacent to the distal end of the shaft. In this case, the shaft consists in particular of the previously disclosed nitinol. The following is provided in a particularly advantageous manner to influence the flexibility or provide a desired flexibility of the shank of the dental screwdriver according to the invention: A) If the shank is made at least partially of Nitinol, then its cross-sectional area is geometrically modified and / or thermally annealed and / or heat-treated. B) If the shank is made at least partially of a material that cannot be heat-treated but can be heat-treated, in particular an iron-containing alloy, then its cross-sectional area is geometrically modified and / or thermally annealed. C) If the shank is made at least partially of a material that can be heat-treated, in particular an iron-containing alloy, then its cross-sectional area is geometrically modified and / or heat-treated.D) If the shaft is at least partially made of a material that can be tempered by mechanical processing, in particular an alloy containing iron, then its cross-sectional area is geometrically modified and / or soft-annealed and / or tempered and / or mechanically processed, in particular bent and / or polished. The previously disclosed methods or process steps are carried out after providing the shaft having a proximal end and a distal end, wherein the proximal end is provided to have a handle and / or the distal end is provided to have an outer surface which is provided to cooperate with a tool in a force-fit and / or form-fit manner, or the distal end is provided to have an abutment screw. Regardless of the material from which the shaft is made, a handle and an abutment screw are attached to it. This is advantageously achieved by forming the shaft with the handle, the shaft with the abutment screw, or the shaft, the handle, and the abutment screw from a single blank in a single process step. Alternatively, the handle and the abutment screw can be attached to the shaft in one or more process steps. Finally, it may be provided that a dental screwdriver, and in a particularly advantageous manner a dental screwdriver of the type disclosed above, is manufactured at least partially by an additive manufacturing process, in particular according to DIN EN ISO 52900:2022-036. Such a process may, in particular, include free-jet binder deposition, material deposition with directed energy input, material extrusion, free-jet material deposition, powder-based melting, or layer lamination. In particular, it can be advantageously provided that at least the shaft, alternatively the shaft with a handle, further alternatively the shaft with a tool, further alternatively the shaft with a handle and a tool, further alternatively the shaft with an abutment screw, further alternatively the shaft with a handle and an abutment screw, is additively manufactured. According to a further preferred embodiment, it is provided that, following the corresponding additive manufacturing, a thermal and / or mechanical treatment of the shaft is carried out in accordance with the previously disclosed manner. It should be noted again at this point that, regardless of how it was manufactured or what material it is made of, the dental screwdriver according to the invention may, according to a preferred embodiment, have a non-constant cross-section when viewed in its longitudinal direction. It should also be noted again that the shaft of the dental screwdriver according to the invention, regardless of how it was manufactured or what material it is made of, may, according to a preferred embodiment, have a predetermined breaking point. Furthermore, the shaft of the dental screwdriver according to the invention, regardless of how it has been manufactured or what material it is made of, can, according to a preferred embodiment, have at least one section of an outer surface which is designed to interact with a tool in a force-locking and / or form-locking manner. In addition, the section of the dental screwdriver according to the invention, regardless of how it was manufactured or what material it is made of, can, according to a preferred embodiment, have an external profile or a threaded section. Finally, according to a preferred embodiment, the thread of the threaded section of the dental screwdriver according to the invention, regardless of how it was manufactured or what material it is made of, can be a thread running in the opposite direction to the thread of the abutment screw. Further features and advantages of the invention are illustrated in the accompanying non-limiting embodiment of the present invention with reference to the accompanying drawing, which is not to scale. Reference numerals shown therein symbolize identical components unless otherwise indicated. Fig. 1 shows a first embodiment of a dental screwdriver according to the invention in a side view. Fig. 2 shows a second embodiment of a dental screwdriver according to the invention in a side view. Fig. 3 shows a third embodiment of a dental screwdriver according to the invention in a side view. Fig. 4 shows a block diagram illustrating two manufacturing processes for a dental screwdriver. Figure 1 shows a side view of a dental screwdriver 1 according to the invention. The dental screwdriver 1 is designed to tighten an abutment screw (not shown) of a known superstructure abutment (not shown) in order to attach a superstructure to a dental implant. For this purpose, the dental screwdriver 1 has a handle 5, a shaft 15 adjoining the handle with a proximal end 10, and a distal end 20 spaced apart from the handle. According to the embodiment shown here, the handle 5 is designed as a star-shaped rotary handle made entirely of nitinol, which interacts with a torque wrench (not shown). A user of the dental screwdriver 1 applies a torque to the handle 5 via the torque wrench, as is known per se. The distal end 20 of the shaft 15 is designed as an external hexagon 25 according to the embodiment shown here, which can engage in a corresponding opening of the abutment screw (not shown) in a form-fit and force-fit manner. The shaft 15 is made entirely of nitinol and is therefore deformable with respect to its longitudinal axis L in such a way that it can also follow a curved screw channel within the superstructure (not shown here). At the same time, it is stable enough to transmit the torque acting via the handle 5 to the distal end 20. The shaft 15 according to the embodiment shown here has a substantially round cross-sectional shape, which is not constant when viewed in the longitudinal direction L. Rather, the shaft 15 includes a first taper 30 in the region of the proximal end 10 and a second taper 35 in the region of the distal end 20, which allows the shaft 15 to more easily follow the contour of the screw channel. The tapers 30, 35 can also be referred to as local tapers, between which a section 40 of comparatively larger diameter is located. As can be seen directly from Fig. 1, the shaft 15 is straight in a non-operating state, i.e., when the dental screwdriver 1 is not in use. Fig. 2 shows an alternative dental screwdriver 1 compared to Fig. 1, which is in its operating state. For the sake of clarity, however, the screw channel in which the shaft 15 is located during the operating state addressed here has been omitted. The shaft 15 of the dental screwdriver 1 shown in Fig. 2 is designed differently from that of Fig. 1. As can be seen directly from Fig. 2, the thickness of the shaft 15 decreases continuously from its proximal end 10 towards the distal end 20. This shaft 15 is also made of nitinol, giving it high deformability combined with torsional stiffness. Thus, according to the embodiment shown here, the shaft 15 is essentially deformable or bendable by 90°, as symbolized by the angle α. However, it should be noted that any other angle α less than 90°, e.g., 5°, 7°, 10°, 15°, 20°, 25°, 30°, etc., or any angle α in between, can also be achieved with the dental screwdriver 1. Furthermore, it is understood that the dental screwdriver 1 also works when the angle α is essentially 0° and therefore there is no curvature.According to the embodiment shown here, the handle 5 is designed as a star-shaped rotary handle made entirely of nitinol, which interacts with a torque wrench not shown here. To fasten an abutment screw (not shown here), the dental screwdrivers 1 depicted in Figures 1 and 2 require – as is known from the prior art – only that the respective shaft 15, with its distal end 20 leading, be inserted into the screw channel of a superstructure until an engaging contact is made between the external hexagon 25 and the corresponding receptacle of the abutment screw, and that torque be applied via the handle 5. Due to its construction with nitinol, the shaft 15 deforms in such a way that it can follow the contour of even a curved screw channel and transmit the required torque to the abutment screw. After the abutment screw has been fastened, the dental screwdriver 1, in particular the shaft 15 along with its distal end 20, is withdrawn from the screw channel.In this direction of movement as well, the shaft 15, due to its nitinol construction, follows the contour of the screw channel, allowing for relatively easy removal. The screw channel of the inserted implant is then filled with a filling material in the usual manner. Figure 3 shows a third embodiment of a dental screwdriver 1 according to the invention in a non-operating state. The shaft 15, which is made entirely of nitinol, comprises a first section 45, which is designed as an external profile in the form of an external hexagon and extends from the proximal end 10 to a second, conically tapered section 50 spaced apart from it. At the far end is the distal end 20 of the shaft 15, which is designed as an abutment screw 55. Since this forms an inherent part of the shaft 15, which is made entirely of nitinol, the abutment screw 55 is also made entirely of nitinol. The abutment screw 55 has an abutment screw head 60, to which an abutment screw cone 65 is attached, tapering in the direction away from the shaft 15. A further abutment screw shaft 70 is attached to the abutment screw cone 65, the shaft having an abutment screw thread 75 at its distal end relative to the shaft 15. It should be noted that the abutment screw cone 65 serves to seal adjacent interfaces. It is therefore conceivable to omit this cone, so that the abutment screw head 60 and the abutment screw shaft 70 are directly connected, with the abutment screw head 60 having a larger diameter than the abutment screw shaft 70. To secure a superstructure (not shown here), the shaft 15, with the abutment screw 55 leading, is inserted through the screw channel of the superstructure until an engaging contact is established between the abutment screw thread 75 and a corresponding receptacle of the implant (not shown here). A torque is then applied via the handle 5, which is made entirely of nitinol. Due to its nitinol construction, the shaft 15 deforms in such a way that it can both follow the contour of the curved screw channel and transmit the required torque to the abutment screw 55. After a defined torque is exceeded, the handle 5 releases at a predetermined breaking point 80, which, according to the embodiment shown here, is positioned in the region of the proximal end 10 of the hexagonal first section 45 of the shaft 15. The handle 5 can thus be removed from the screwed-in assembly.The remaining part of the shaft 15 in the screw channel remains in place, and after completion of the screwing process, it is embedded in a filling material known per se that seals the screw channel. It should be noted that the section 45 shown in Fig. 3 is depicted with an external profile only as an example. Alternatively, although not shown here, it is possible to provide section 45 with a thread. This thread has a thread opposite to the thread 75 of the abutment screw 55. Thus, if the thread 75 of the abutment screw 55 is a right-hand thread, as shown in Fig. 3, then the thread provided in section 45 is a left-hand thread. After insertion of the implant, the abutment screw 55, which has the remaining part of the shaft 15, can be removed again using a suitable tool (not shown here) that engages the thread of section 45. It should also be noted that the previously described dental screwdriver 1 may not be made of nitinol, but rather of an iron-containing alloy. This alloy has, for example, the following composition: 15 to 20 wt.% chromium, 5 to 14 wt.% nickel, up to 2.5 wt.% silicon, up to 1 wt.% molybdenum, 0.04 to 0.17 wt.% carbon, up to 0.13 wt.% nickel, up to 0.05 wt.% phosphorus, up to 0.017 wt.% sulfur, and iron such that the sum of all components equals 100 wt.%, or 16 to 21 wt.% chromium, 7 to 13 wt.% nickel, 0.07 to 0.16 wt.% carbon, and iron such that the sum of all components equals 100 wt.%. Fig. 4 now shows a block diagram illustrating manufacturing processes for a dental screwdriver 1 of the type described above. In a first step S1, it is clarified or checked whether the shaft 15 of the dental screwdriver 1 is made of an iron-containing alloy or of nitinol. In the event that the shaft 15 is made of an iron-containing alloy, the shaft 15 is provided, as symbolized in step S2. According to the embodiment shown here, the shaft 15 has a handle 5 at its proximal end 10 and an abutment screw 55 at its distal end 20, and these are formed integrally. In other words, the aforementioned elements are made of the same iron-containing alloy. It should be noted that, instead of the abutment screw 55, an external surface may also be provided at the distal end 20, which is designed to interact with a tool in a force-fit and / or form-fit manner. For example, the distal end 20 may be designed as an external hexagon 25. The shaft 15 is then thermally treated in step S3 by annealing a section of the shaft not shown in Fig. 4. After completion of the thermal treatment, the dental screwdriver 1 is finished, as symbolized by step S4. In the event that the shaft 15 is not made of an iron-containing alloy but of nitinol, the shaft 15 is provided as symbolized in step S5. According to the embodiment shown here, the shaft 15 has a handle 5 at its proximal end 10 and an abutment screw 55 at its distal end 20, and these are formed integrally. In other words, the aforementioned elements consist of the same nitinol. It should be noted that, instead of the abutment screw 55, an external surface may also be provided at the distal end 20, which is designed to interact with a tool in a force-fit and / or form-fit manner. For example, the distal end 20 may be formed as an external hexagon 25. In a further step S6, according to the embodiment shown here, two tapers 30, 35 are introduced into the shaft 15. It should be understood, however, that step S6 is merely optional and could therefore be omitted. The dental screwdriver 1 is then completed, as symbolized by step S 4. It should be noted that the insertion of tapers 30, 35 can optionally also be carried out on a shaft formed from an iron-containing alloy, as symbolized by the arrow shown with a dashed line. A direct connection between steps S3 and S4 is omitted in this case. If the shaft 15 lacks a handle 5 at its proximal end 10 and / or an abutment screw 55 at its distal end 20, these must be added. This can be done, although not shown in Fig. 4, immediately before step S4, i.e., after steps S3, and optionally S6 in the case of a dental screwdriver 1 made of an iron-containing alloy, or after steps S5, and optionally S6 in the case of a dental screwdriver 1 made of nitinol. It is understood that the previously described process steps could also be carried out with reversed materials (i.e., Nitinol instead of an iron-containing alloy or an iron-containing alloy instead of Nitinol). It would also be possible, instead of heat treatment according to step S3, to provide a mechanical treatment of the section of the shaft 15 such that at least a part of the section of the shaft 15 located between the proximal end 10 and the distal end 20 is made stiffer than the rest of the shaft 15. The mechanical treatment is carried out, for example, by polishing and / or cold forming. Finally, although not shown in a separate figure, it is possible to manufacture a dental screwdriver using an additive manufacturing process. In this case, at least the shank, or alternatively the shank with a handle, or further alternatively the shank with a tool, or further alternatively the shank with a handle and a tool, or further alternatively the shank with an abutment screw, or further alternatively the shank with a handle and an abutment screw, is additively manufactured. If desired, a thermal and / or mechanical treatment of the shank can be carried out after the respective manufacturing process, according to at least one of the previously disclosed methods. Such a dental screwdriver 1 can, for example, be designed as shown in Figures 1, 2 to 3. Reference symbol list 1 Dental screwdriver 5 Handle 10 Proximal end 15 Shank 20 Distal end 25 External hexagon 30 First taper 35 Second taper 40 Section 45 First section 50 Second section 55 Abutment screw 60 Abutment screw head 65 Abutment screw cone 70 Abutment screw shank 75 Abutment screw thread 80 Break point L Longitudinal axis S1 ... S6 Procedure steps α Angle

Claims

Dental screwdriver (1) configured to connect an abutment screw (55) of a suprastructure abutment to a dental implant, comprising a shaft (15) having a proximal end (10) and a distal end (20), wherein a handle (5) is located at the proximal end (10), wherein the shaft (15) is flexible and has an abutment screw (55) at its distal end (20) configured to connect the suprastructure abutment to the dental implant, characterized in that the shaft (15) has a predetermined breaking point (80). Dental screwdriver (1) according to claim 1, characterized in that the shaft (15) is at least partially made of nitinol or of an iron-containing alloy. Dental screwdriver (1) according to claim 1 or 2, characterized in that the shaft (15), viewed in its longitudinal direction (L), has a non-constant cross-section. Dental screwdriver (1) according to one of the preceding claims, characterized in that the shaft (15) has a first taper (30) at its area adjacent to the proximal end (10) and / or a second taper (35) at its area adjacent to the distal end (20). Dental screwdriver (1) according to one of the preceding claims, characterized in that the shaft (15) and the abutment screw (55) and / or the handle (5) are formed in one piece. Dental screwdriver (1) according to one of the preceding claims, characterized in that the shaft (15) has at least on a section (45) an outer surface which is designed to cooperate with a tool in a force-locking and / or form-locking manner. Dental screwdriver (1) according to claim 6, characterized in that the section (45) is an external profile or a threaded section. Dental screwdriver (1) according to claim 7, characterized in that the thread of the threaded section is a thread running opposite to the thread (75) of the abutment screw (55). Method for manufacturing a dental screwdriver (1), characterized by the following steps: a) providing a shaft (15) having a proximal end (10) and a distal end (20), wherein the proximal end (10) is provided to have a handle (5) and / or the distal end (20) is provided to have an outer surface which is provided to engage with a tool in a force-fit and / or form-fit manner, or the distal end (20) is provided to have an abutment screw (55);and b) performing a thermal and / or mechanical treatment of the shaft (15) on at least one shaft section located between the proximal end (10) and the distal end (20), and / or c) introducing a first taper (30) in a shaft section adjacent to the proximal end (10) of the shaft (15) and / or introducing a second taper (35) in a region adjacent to the distal end (20) of the shaft (15), and / or d) performing a mechanical treatment on at least one section of the shaft (15) located away from the proximal end (10) and / or the distal end (20) such that the strength of the section is greater than the strength of the shaft (15) in the region of the proximal end (10) and / or the distal end (20). Method for manufacturing a dental screwdriver (1) according to claim 9, characterized in that the mechanical treatment of the section of the shaft (15) comprises polishing and / or cold forming. Method for manufacturing a dental screwdriver (1) according to one of claims 9 or 10, characterized in that at least a part of the dental screwdriver (1) is manufactured by an additive manufacturing process.

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