Drill bit and method for performing osteotomy using this drill bit

Abstract

This disclosure provides a drill bit including an apical end, a coronal end, and a longitudinal axis extending between the apical end and the coronal end. The drill bit further includes a drill bit core extending along the longitudinal axis, at least two grooves, each groove defined by a concave surface that forms a recess along the drill bit core, and an apical rake face at the apical end. The apical edges of the concave surfaces and the apical edges of the drill bit core define the shape of the apical rake face such that the apical rake face defines the contour of a retaining arm at the apical end, each retaining arm formed between the concave surfaces of adjacent grooves. This disclosure also provides a method for performing an osteotomy using the drill bit.

Description

Technical Field

[0001] The present disclosure relates to a drill bit for preparing an implantation site for a dental implant. The present invention also relates to performing osteotomy to prepare the implantation site.

Background Art

[0002] Before inserting a dental implant, it is necessary to prepare a recess in the patient's maxilla or mandible. This osteotomy is an important step in providing a dental implant and significantly affects the osseointegration of the implant and its long-term success.

[0003] Considering that the density, orientation, and quality of bone vary from patient to patient, in many cases, various tools need to be used to prepare an appropriate implant-receiving recess. However, the more interdependent the tools used to create the recess, the more extensive the treatment protocol becomes. This makes decisions regarding the details of such protocols quite complex and time-consuming. Furthermore, the alignment of these various tools for preparing the implant implantation site can be quite difficult.

[0004] It is necessary to consider that the jawbone has a relatively hard outer layer (i.e., cortical bone) and beneath it has a weaker spongy bone structure (i.e., cancellous bone). The cortical bone providing the hard cortex is much denser and less elastic than cancellous bone. When preparing a bone recess for receiving a dental implant, the drill bit must create this recess that extends from the cortical bone into the cancellous bone. Therefore, the drill bit needs to be able to machine different types of bone tissue in the patient during osteotomy.

[0005] During the creation of osteotomy, the drill bit is guided by a dental professional. Therefore, the implementation of osteotomy is also influenced by the dental professional.

[0006] Considering the above, continuous efforts have been made to improve the process of creating recesses in bone tissue in preparation for the insertion of dental implants. In this regard, WO2017 / 129828A1 discloses a drill bit for preparing bone tissue configured to simultaneously condense and cut bone tissue. [Overview of the project]

[0007] Generally, the objective has been to provide a drill bit that facilitates osteotomy, unaffected by variations in bone quality, not only within the patient's jawbone but also within different jawbones of the patient or between patients, so that the necessary bone recess for receiving a dental implant is formed as needed, i.e., the bone recess is prepared without excess or deficiency.

[0008] Another objective has been to provide dental professionals with feedback on the progress of preparing the implant placement recess.

[0009] With these objectives in mind, the drill bit and method for performing the osteotomy are provided as defined in the independent claim. The dependent claims specify preferred features of the claimed invention.

[0010] A first aspect of this disclosure provides a drill bit comprising an apical end, a coronal end, and a longitudinal axis extending between the apical end and the coronal end. The drill bit further comprises a drill bit core extending along the longitudinal axis, at least two grooves, each groove defined by a concave surface forming a recess along the drill bit core, and an apical end face at the apical end. The apical edge of the concave surface and the apical edge of the drill bit core define the shape of the apical end face such that the apical end face defines the contour of a retaining arm at the apical end, each retaining arm formed between the concave surfaces of adjacent grooves. At least one of the at least two grooves extends along the longitudinal axis from the apical end to at least 70% of the length of the portion of the drill bit configured to interact with bone tissue, preferably over the entire length of the portion of the drill bit configured to interact with bone tissue.

[0011] Along the longitudinal axis, the straight-line distance between the highest point of at least one groove and the highest point of the crown of that groove is at least 50% of the total straight-line distance of the drill bit.

[0012] Preferably, at least one groove extends along the longitudinal axis L for the entire length of the drill bit (the working portion). In other words, the first end of at least one groove is at the apical end of the drill bit, and the second end of this groove is at the crown end of the drill bit. At least one groove may extend continuously between these first and second ends. The drill bit may include two or more grooves having the same characteristics as described above.

[0013] By having at least one cutting groove extending over most of the drill bit, it becomes possible to cut bone tissue along the entire length of the groove. The shape / volume of the osteotomy created by the cutting groove can substantially correspond to the shape / volume of the implant core. When the implant is then placed in the prepared osteotomy, only the threads (or multiple threads) of the implant (not the core of the implant) compress the bone tissue. This preserves the bone tissue to the greatest extent possible. In other words, when the implant is placed in the osteotomy, only the threads of the implant push the bone radially relative to the implant axis. Thus, most of the bone tissue is preserved from destructive overcompression, which ultimately leads to good osseointegration. This is particularly important for dense bone tissue, as overcompression can damage dense bone tissue and potentially cause a fracture of part of the patient's jaw. The drill bit according to the present invention is particularly adapted for preparing osteotomies in this type of hard bone.

[0014] The above advantages are amplified in embodiments of the present invention in which at least one cutting groove extends along the entire length of the drill bit.

[0015] Each groove extends from the apical rake face toward the coronal end. In a cross-section perpendicular to the longitudinal axis, the concave surface of the groove forms a recess along the contour of the drill bit core. At the apical rake face, each groove creates a recess within the contour of the end rake face.

[0016] Between adjacent recesses, the contour of the end rake face is arm-shaped and represents the contour of the retaining arm. This contour preferably has a longitudinal extension radially (relative to the longitudinal axis) and extends from the central region of the apex end rake face to the outer peripheral edge of the apex end rake face (generally defined by the apex edge of the drill bit core). The number of retaining arms is equal to the number of grooves. Preferably, the drill bit contains three grooves.

[0017] The rake face at the end of the drill bit dulls the tip, resulting in a reduction in the drill bit's forward cutting ability, at least. In other words, when the apical rake face comes into contact with bone tissue, the rake face increases the force and torque required to advance the drill bit further.

[0018] Furthermore, the drill bit core is preferably tapered along at least a portion of the core toward the apex of the drill bit. This tapered portion serves to increase the diameter of the hole in the bone tissue as the drill bit advances. In addition, cutting grooves extending along this tapered portion of the drill bit cut the bone tissue at each tip of its cutting edge, creating an osteotomy or hole. The osteotomy is enlarged at each tip by the shape of the drill, preparing it to the size of the dental implant.

[0019] When the apical rake face of the drill bit contacts the bottom of the pilot hole in the bone tissue at the implant site, the retention arm is configured to interact with the bone tissue to generate a retention force that counteracts the driving torque applied to the drill bit. In other words, the frictional force resisting the driving torque applied to the drill bit is generated when the retention arm contacts the bone tissue at the bottom of the pilot hole, especially during surface contact.

[0020] As a result, the retaining arm at the tip of the drill bit provides feedback to the user indicating that the end of a pre-prepared hole (i.e., a pilot hole) in the bone tissue has been reached. This serves to prevent the osteotomy from being under-prepared or over-prepared.

[0021] The drill bit may further include at least one guide thread protruding from the drill bit core. The guide thread extends helically along the drill bit core and is preferably tapered toward the apex. The guide thread is particularly a single-start thread.

[0022] The guide threads on the drill bit convert the rotational motion of the drill bit into a predetermined feed rate, thereby enhancing control of the drill bit's advance into the bone tissue. More specifically, each rotational motion advances the drill bit by a distance corresponding to the pitch of the guide threads. In this way, the guide threads particularly facilitate the insertion of the drill bit into a pre-prepared pilot hole at the implant site.

[0023] The guide threads may taper toward the crown of the drill bit. That is, the outer diameter of the guide threads decreases in the crown-to-crown direction. Preferably, the height of the guide threads is substantially constant in the direction of the longitudinal axis. Alternatively, the height may decrease in this direction. Preferably, the guide threads do not extend to the crown of the drill bit or to the portion where the retaining arm is positioned.

[0024] The guide thread is preferably formed such that it converts torque into forward driving force for the drill bit into a pre-prepared hole, but is insufficient to advance the drill bit into unprepared bone tissue. Instead, the guide thread loses grip once a certain torque limit is reached, and begins to rotate freely without drilling deeper into the tissue.

[0025] Therefore, the guide thread can enhance the above-mentioned effect of providing feedback by increasing the torque until the thread loses grip and spins, thereby reaching the end of a pre-drilled or pilot hole. Thus, the rake face of the top end, the retaining arm, and the guide thread interact with each other when providing a reactive feedback torque.

[0026] The radial height of the guide thread is smaller than the radial extension of the contour of the retaining arm, particularly at the rake face of the apex.

[0027] As described above, the contour of the retention arm on the tip scooping surface extends from the central region to the outer edge of the tip scooping surface. The length of the contour from the central region to the outer edge is preferably greater than the radial height of the guide thread. Generally, the longer the retention arm, the greater the reaction torque when the drill bit reaches the bottom of the hole pre-drilled.

[0028] Each retention arm may have a radial extension that is greater than the circumferential width at its tip formed by the top edge of the drill bit core.

[0029] The guide thread may have a non-circular circumferential contour, which may preferably be a trio-oval contour.

[0030] The non-circular, and particularly the trio-oval contour, has the advantage of functioning as a guide thread that forms a thread groove more easily than a normal thread. It also functions by gradually condensing bone tissue along the path of the guide thread. In this way, the bone tissue is preserved instead of being cut, reducing the influence of the guide thread on the shape of the hole formed by the drill bit.

[0031] Furthermore, the drill bit core may have a non-circular contour in a cross-section perpendicular to the longitudinal axis, and in the longitudinal direction of the drill bit, the non-circular contour may preferably rotate about the longitudinal axis so as to create a non-circular twist drill bit core.

[0032] Such a non-circular contour of the drill bit core utilizes the elasticity of the bone tissue when creating a recess in the bone tissue during insertion of the drill bit while it is rotating. Without wishing to be bound by any theory, the non-circular contour helps to create a recess that allows the drill bit to maintain its insertion direction. Also, due to the condensing effect on the bone tissue, it may have a positive effect on the primary stability of the dental implant inserted into this recess. The non-circular contour of the drill bit core may also provide a relief angle on the core to assist in cutting the bone tissue.

[0033] A non-circular twisted drill bit core has the advantage of distributing the forces arising from its non-circular contour when the drill bit is inserted into bone tissue along its circumferential direction. This is particularly important in preventing the drill bit from being offset when it enters the pilot hole.

[0034] The non-circular profile of the drill bit core and the non-circular profile of the guide thread may be formed to have a circumferential offset. Such a configuration also enhances the force distribution along the circumferential direction of the drill bit and prevents the drill bit from being misaligned or offset from its desired trajectory during insertion.

[0035] Preferably, the top edge or circumferential edge of the rake face at the top end is positioned in a plane perpendicular to the longitudinal axis.

[0036] This structural feature allows the retaining arm to contact the bottom of the pre-drilled hole almost simultaneously. As a result, the reaction torque increases more rapidly, providing clearer feedback. In this regard, at least the top surface of the retaining arm, and preferably the apical rake face, are flat to cause surface contact with the bone tissue at the bottom of the pilot hole.

[0037] The concave surfaces of each groove and the circumferential surfaces of the drill bit core preferably form a cutting edge. If guide threads are provided, the cutting edge more preferably also includes the contour of the guide threads.

[0038] Therefore, such grooves may not only form a retaining arm on the apical rake face, but also serve as cutting grooves that help prepare a recess in the bone tissue substantially corresponding to the rotational shape of the drill bit core. The cutting edge facilitates the formation of the bone recess and, furthermore, allows the retaining arm and, if present, the guide threads, to contact the bottom of the pre-drilled hole, resulting in a more detectable increase in torque that resists further rotation of the drill bit.

[0039] The concave surface and the apical rake face may have cutting edges formed at least partially on the apical edge of each concave surface, the cutting edges having a forward rake angle and substantially no forward relief angle.

[0040] Because the edge formed on the rake face of the tip of a drill bit essentially has no forward relief angle, the forward cutting ability of the rake face is significantly reduced.

[0041] Furthermore, because the groove extends along the longitudinal direction of the drill bit, the forward rake angle is relatively large. As a result, the surface of the retaining arm is at the edge formed between the concave surface and the apical rake face, and this surface faces the predetermined rotational direction of the drill bit, thus collecting or scraping bone tissue at the bottom of the pre-drilled hole. This bone tissue tends to generate friction and torque that reacts to the rotation of the drill bit, thus providing feedback.

[0042] At least two grooves extend spirally, particularly along the core of the drill bit. The angle between the rake face at the top of the drill bit and the concave face of the groove is formed by the spiral extension of the groove, supporting the function of the retaining arm by collecting or scraping bone tissue at the apical edge where the rake face and concave face meet. Furthermore, the spiral path of the groove provides a more uniform load distribution along the circumferential direction of the drill bit. This is particularly advantageous when drilling at low speeds, as it results in controlled preparation of the bone recess or implant placement recess. In this respect, three grooves are preferable.

[0043] Furthermore, this disclosure provides a method for creating an osteotomy using a drill bit, and more particularly the drill bit described above. The method includes the steps of drilling a hole with a pilot drill and enlarging the size of a hole for insertion of a dental implant using the drill bit. The drill bit includes a drill bit core, at least two grooves, each groove defined by a concave surface that forms a longitudinal recess along the drill bit core, an apical rake face at the apical end of the drill bit, and retaining arms extending crown-like from the apical rake face. Each retaining arm is formed between the concave surfaces of adjacent grooves. When the bottom of the hole drilled by the pilot drill contacts the apical rake face, the retaining arms generate a braking force that can be used to stop the rotation of the drill bit.

[0044] When the apical rake face makes contact with the bottom of the hole, it acts as a stop. Furthermore, as the retaining arm rotates, a torque is generated that counteracts the driving torque of the drill bit due to the collection of bone tissue or bone debris at the bottom. This provides feedback to the dental professional using the drill bit, or to a sensor or mechanism such as a torque limiter, as a signal to stop the drilling process.

[0045] Preferably, the tip of the pilot drill has a diameter larger than the diameter of the apical rake face. This has the advantage that, at the start of preparing the bone recess with the drill bit, the apical rake face does not come into contact with the bone tissue until the drill bit reaches the end of the pilot hole. Otherwise, the apical rake face of the drill bit will hinder the drilling process, at least significantly reducing its forward drilling capability. Furthermore, the torque signal more clearly indicates the end of preparation.

[0046] The diameter at the tip of a pilot drill refers to the diameter at the boundary between the pre-cutting edge formed by the tip angle of the pilot drill (if any) and the circumferential surface extending along the longitudinal axis of the pilot drill.

[0047] The following figures illustrate preferred embodiments of the features described herein. These embodiments should not be construed as limiting, but are merely for the purpose of enhancing the understanding of this disclosure. [Brief explanation of the drawing]

[0048] [Figure 1] This is a partial side view of the drill bit according to the present disclosure. [Figure 2] Figure 1 shows a partial view of the drill bit, specifically the tip of the drill bit in a perspective view. [Figure 3] This is a front view of the rake face at the tip of a drill bit. [Figure 4] This is a cross-sectional view of the drill bit according to this disclosure. [Figure 5] This is another cross-sectional view of the drill bit according to this disclosure. [Figure 6] This is yet another cross-sectional view of the drill bit according to this disclosure. [Modes for carrying out the invention]

[0049] Hereinafter, exemplary embodiments of tools for preparing recesses in bone tissue, in particular embodiments of the drill bit 1 according to this disclosure, will be described with reference to the accompanying drawings.

[0050] Figure 1 shows an exemplary embodiment of a drill bit 1 according to the present disclosure. The drill bit 1 has a apical end 2 and a crown end (not shown). It extends along a longitudinal axis L which also functions as a rotation axis. The crown end is preferably configured to be coupled to a dental drill (not shown) to transmit driving torque to the drill bit 1.

[0051] The drill bit 1 includes a drill bit core 20 having a circumferential surface 21. The drill bit core 20 is preferably tapered in the crown-to-apex direction (i.e., towards the apex 2). The drill bit 1 includes at least two grooves 40. Each groove 40 is defined by a concave surface 41. The concave surface 41 forms a longitudinal recess (i.e., groove 40) that starts from the apex 2 and extends along the drill bit core 20. Thus, each groove 40 has a concave contour defined by the concave shape of the concave surface 41.

[0052] The drill bit core 20 preferably has a substantially continuous profile along the longitudinal axis L of the drill bit 1. The profile of the drill bit core 20 is "substantially" continuous by the groove 40 and the guide thread 30 (if present). In other words, the profile does not include any discontinuities, such as diametrical steps in the drill bit core 20, which are essentially perpendicular to the longitudinal axis L.

[0053] At the apex 2, the drill bit 1 includes an apex rake face 10. The apex rake face 10 is preferably oriented substantially perpendicular to the longitudinal axis L of the drill bit 1. As shown in Figure 2, the profile of the apex rake face 10 is defined by the apex edge 42 and apex edge 22 of the concave surface 41. At the apex edge 22 of the drill bit core 20, the drill bit core 22 may include a chamfered portion or a rounded edge 23. The chamfered portion 23 does not form part of the apex rake face 10.

[0054] The top edge 42 of the concave surface 41 and the top edge 22 of the drill bit core 20 shape the contour of the top rake face 10, including the arm-shaped radial extensions 12 (in the exemplary embodiment of Figure 2, the top rake face 10 has three arms). Each of these arm-shaped radial extensions 12 has a tip edge 14a defined by the top edge 22 of the drill bit core 20 and two side edges 14b and 14c defined by the top edges 42 of the concave surfaces 41 of the two adjacent grooves 40. In particular, the opposing side edges 14b and 14c of each arm 12 may be defined by substantially half the length of the top edge 42 of the groove 40. Preferably, each arm-shaped extension 12 is substantially symmetric with respect to a radial symmetry axis extending from the longitudinal axis L.

[0055] The arm-shaped extension 12 extends from the central region 11 of the apical end rake face 10. Preferably, the central region 11 is defined by a virtual circle (shown as a dashed circle in Figures 2 and 3) that fits the apical edge 42 of the concave surface 41.

[0056] Each of the arm-shaped extensions 12 defines the contour of a retaining arm 50 for collecting bone debris or scraping away bone tissue upon contact with bone tissue at the bottom of a pilot hole. Such pilot holes are pre-created using a drill bit 1 to prepare a bone recess into which a dental component, such as a dental implant, can be inserted.

[0057] Each retaining arm 50 extends along a portion of the drill bit core 20 from the apical rake face 10 to the apical end 2 of the drill bit 1. When the drill bit 1 rotates, the sides 51 of each retaining arm 50 facing the rotational direction collect bone debris, which then reacts to the driving torque applied to the drill bit 1 (e.g., by a dental handpiece). Thus, the apex of the drill bit core 20, including the retaining arms, extends along a distance of the drill bit suitable for collecting bone tissue at the bottom of the pilot hole. Each retaining arm 50 extends longitudinally from the apical rake face 10 to the corresponding guide thread 30.

[0058] Generally, the longer the radial extension of the retaining arm 15, the higher the torque generated by scraping or collecting bone tissue that reacts to the driving torque that drives the drill bit 1.

[0059] When the pilot hole is formed as a blind hole (i.e., with a flat bottom), the rake face 10 at the top of the pilot hole is in contact with the bottom of the pilot hole, and as the drill bit 1 rotates, the retaining arm 50 collects and accumulates bone debris.

[0060] If the drill used to create the pilot hole has a conical tip, the pilot hole will be tapered at its end. This tapering allows the drill bit 1 to collect and accumulate bone debris when it contacts the conical wall at the bottom of the pilot hole. As the drill bit 1 advances further into the pilot hole, its bottom is reshaped into a blind hole. As a result, the rake face 10 at the apex comes into surface contact with the bone tissue.

[0061] Therefore, regardless of the shape of the bottom of the pilot hole, the drill bit 1 exhibits increased torque when it reaches the edge of the pilot hole. This increase in torque can function as a feedback signal to stop the drilling process. For example, this increase in torque may activate a torque limiting device that automatically stops the rotation of the drill bit 1.

[0062] Therefore, such a design of the drill bit 1 can ensure that the recess created by the drill bit 1 is neither under-prepared nor over-prepared.

[0063] Furthermore, when the rake face 10 of the drill bit makes surface contact with bone tissue, the rake face 10 is designed to have almost no forward drilling capability; that is, the rake face 10 of the drill bit 1 has virtually no ability to cut into the surface of bone tissue that is parallel to the rake face 10.

[0064] In this respect, due to the flat surface of the arm, the top rake face 10 essentially does not have a forward rake angle (i.e., a 0° rake angle) at the top edge 42 of each groove 40. Depending on the trajectory of the extension of the groove 40 along the drill bit core 20, the top end 2 of the drill bit 1 may also lack a forward rake angle at each top edge 42 of the groove 40 (i.e., have a 0° rake angle).

[0065] Preferably, the groove 40 extends spirally along the longitudinal axis L of the drill bit core 20. In this specification, the top edge 42 of the groove 40 may have a non-zero forward rake angle, however, this forward rake angle is fairly small (preferably less than 20°, 15°, 10°, or 5°). As a result, the top edge 42 tends to scrape and collect bone tissue, thus contributing to generating a torque that counteracts the driving torque of the drill bit 1.

[0066] The grooves 40 may also vary their pitch in the apex-crown direction. In particular, their pitch may decrease in this direction so as to reduce the forward rake angle at the apex edge 42.

[0067] The exemplary embodiment shown in the figure includes three grooves. Alternatively, there may be two, four, or five grooves 40. At the tip 2 of the drill bit 1, these grooves 40 define two, four, or five arms, respectively. It has been found that a number of three grooves 40 is particularly advantageous for preparing the bone recess by the drill bit 1.

[0068] The groove 40 preferably forms a cutting edge 43 together with the drill bit core 14. More specifically, the surface side of the groove facing the rotational direction forms a cutting edge with the circumferential surface 21 of the drill bit core 20. Thus, the drill bit 1 has radial cutting capability when it rotates.

[0069] As described above, at least a portion of the drill bit core 20 may be tapered in the coronal-apical direction. Combined with the groove 40, this gives the drill bit 1 forward cutting capability. In other words, such a configuration of the drill bit 1 cuts through the bone tissue as it advances into the bone tissue, facilitating the insertion of the drill bit 1.

[0070] Nevertheless, the forward cutting capability of the drill bit 1 due to the interaction between the concave surface 41 and the circumferential surface 21 of the drill bit core 20 does not affect the limited cutting capability of the apical rake face 10 at the apical end 2 due to its blunt configuration. Therefore, the cutting capability of the cutting edge 43 at the edges of the circumferential surface 21 and the concave surface 41 serves to give the bone recess the desired shape.

[0071] As shown in the attached figure, the drill bit 1 may include a guide thread 30. The guide thread extends radially from the drill bit core 20 and along at least a portion of the drill bit core 20 with respect to the longitudinal axis L. Preferably, the guide thread 30 does not extend to or within the portion of the top end 2 of the drill bit that includes the retaining arm 50.

[0072] The guide thread 30 extends along the drill bit core 20 and is configured to pull the drill bit 1 into the bone tissue at a predetermined speed. This speed depends on the rotation-to-advance ratio set by the pitch of the guide thread 30. Preferably, the pitch of the guide thread 30 is in the range of 0.4 mm to 3 mm, more preferably in the range of 0.8 to 1.5 mm, and even more preferably in the range of 1.0 to 1.2 mm. The guide thread 30 is preferably configured as a single-start thread, but may be designed as a double-start or triple-start thread. The guide thread 30 gives the drill bit 1 self-drilling capability.

[0073] Preferably, the guide thread 30 is configured such that when the apical rake face 10 makes surface contact with the bone tissue at the bottom of the pilot hole, it generates a forward force smaller than the forward force required to overcome the resistance of the apical rake face 10.

[0074] In cross-section, the guide thread 30 has a thread profile with an average thread height from the thread base to the tip of the guide thread 30 that is smaller than the diameter of the rake face 10 at the top of the drill bit 1 (see Figures 2 and 3). The average thread height of the guide thread is in the range of 1% or 2% to 5%, 10%, or 30% of the diameter of the rake face 10.

[0075] Furthermore, the maximum height of the guide thread 30 must not exceed 50% of the diameter of the rake face 10 at the top end.

[0076] The height of the guide thread 30 has the effect that, when the top rake face 10 is brought into contact with the bottom of the pilot hole, the forward force generated by the guide thread 30 is insufficient to overcome the resistance to the forward movement of the drill bit 10 caused by the top rake face 10 making surface contact with the bottom of the pilot hole. As a result, the increase in torque can be generated and used as a feedback signal to the user, sensors, mechanisms, etc., to stop the application of driving torque to the drill bit 1 or to indicate that the bottom of the pilot hole has been reached.

[0077] In other words, when the rake face 10 at the tip of the drill bit 1 comes into contact with bone tissue at the bottom of the pilot hole, the driving torque needs to be increased to enable continuous rotation of the drill bit 1. In particular, this need for increased torque can be detected and used as a feedback signal.

[0078] For example, an increase in torque may occur automatically by the motor driving the drill bit 1, particularly an electric motor. Preferably, a torque limiter is included in the drive train of the drill bit 1 to accommodate such an increase by stopping the rotation of the drill bit 1. Otherwise, such an increase in driving torque could cause the guide thread 30 to slip or spin. In such a scenario, the advance of the drill bit 1 may also be stopped when the bottom of the pilot hole and the rake face of the top end of the drill bit 1 come into contact.

[0079] As previously described and shown in the figure, the guide thread 30 may be formed at least partially as a tapered thread that tapers in the crown-to-crown direction (i.e., towards the apex). The guide thread 30 is preferably tapered along a portion of the drill bit core 20, which is also tapered. Furthermore, the tapered guide thread 30 and the tapered drill bit core 20 preferably correspond to each other. In other words, the tapered guide thread 30 and the tapered drill bit core 20 preferably have the same angle with respect to the longitudinal axis L, or extend along a path parallel to the cross section along the longitudinal axis L.

[0080] Furthermore, the guide thread 30 may have a non-circular profile, particularly a tri-oval profile. Such a non-circular profile of the guide thread 13 may also be twisted along the drill bit 1 about the longitudinal axis L.

[0081] The non-circular profile, particularly in combination with the groove 40, has the advantage of creating a thread path in bone tissue based on cutting and condensation. In other words, the tread path is partially created based on the elastic deformation of the bone tissue. The creation of a thread path based on the elastic deformation of the bone tissue can lead to increased torque over a longer period of time, as the apex rake face 10 reaches the end or bottom of the pilot hole, and even when spinning, as the drill bit 1 begins to spin, the guide threads 30 of the drill bit 1 may tend to deform the bone tissue rather than cut it.

[0082] Furthermore, or alternatively, the drill bit core 20 may have at least partially non-circular profiles in a cross section perpendicular to the longitudinal axis L. Such a configuration of the drill bit core 20 may also be twisted, i.e., the non-circular profiles rotate about the longitudinal axis L in a cross section along the crown-apex direction. Furthermore, if present, the guide threads 30 and the drill bit core 20 with non-circular profiles may be twisted relative to each other (i.e., one or both are twisted about the longitudinal axis).

[0083] At the apex (i.e., the apex rake face), the drill bit core 20, and preferably the portion forming the retaining arm 50 along the drill bit core 20, may have a circular contour. This circular contour changes in a crown shape to a non-circular contour.

[0084] The non-circular contour of the drill bit core allows the drill bit 1 to remain in place along its trajectory as the apical rake face 10 reaches the bottom of the pilot hole, preparing the bone recess. The non-circular contour, in combination with the groove 40 including the cutting edge 43, is configured to form the bone recess based on the cutting and elastic deformation of the bone tissue. The elastic deformation can hold the drill bit 1 in place when the apical rake face 10 contacts the bone tissue. If the drill bit 1 continues to rotate, it can also prevent further cutting action of the drill bit 1 by preventing the drill bit 1 from oscillating.

[0085] The effect of non-circular contours on recess formation and the cutting behavior of the drill bit is described in further detail in EP21 208 105A, which is incorporated herein by reference.

[0086] More specifically, the relationship between the groove 40 and the non-circular cross-section of the drill bit core 20 favorably influences the way in which the drill bit 1 forms a desired bone recess by cutting and deforming bone tissue.

[0087] Figures 4 to 6 show cross-sectional views of the drill bit 1 at different positions along the longitudinal axis L. These cross-sectional views show the cross-section of the drill bit 1 perpendicular to the longitudinal axis L as viewed in the apex-crown direction. Each of these cross-sectional views shows the outline 3 of the drill bit 1, which may include outline sections arising from features such as grooves 40 or guide threads 30.

[0088] The cross-sectional views in Figures 4 to 6 each include, for comparison, the basic outline 25 of the drill bit core 20, i.e., the outline of the drill bit core 20 representing the basic shape without any additional features such as grooves 40 or guide threads 30. In the cross-sectional view of Figure 6, the basic outline 3 allows us to show the position where the outermost tip 24' of the drill bit core 20 without grooves 40 is located.

[0089] The cross-sectional outline 3 of the drill bit core 20 preferably includes at least one outermost tip 24. The at least one outermost tip 24 is substantially located at a first radial distance r1 from the longitudinal axis L. As a result, the radial distance r1 at the outermost tip 12 represents the maximum radial distance of the tip on the basic outline 25 (or outline 3) to the longitudinal axis L.

[0090] In Figures 4 to 6, the basic outline 25 of the cross-section of the drill bit core 20 includes three outermost tips 24. However, any other number of outermost tips 12 may be formed, such as one, two (i.e., oval), three (i.e., tri-oval), four, five, or six outermost tips 12. Preferably, the outermost tips 12 are uniformly distributed along the outline of the drill bit core 20.

[0091] The cross-sectional views in Figures 4 to 6 each show a cross-section of the drill bit 1 at different points along the longitudinal axis L. In these cross-sectional views, a given direction of rotation of the drill bit 1 is defined as the counterclockwise direction indicated by the curved arrow.

[0092] The drill bit 1 may include at least a portion along the longitudinal axis L in the apex-crown direction in which the diameter of the drill bit core 20 and / or the first radial distance r1 increases. This increase preferably corresponds to an increase in the diameter of a dental implant (not shown) that is embedded in a recess created using the drill bit 1.

[0093] Furthermore, the drill bit 1 may include at least a portion along the longitudinal axis L such that the diameter and / or first radial distance r1 of the drill bit core 20 remain substantially the same. Such a portion may also be shaped to correspond to the implant to be embedded.

[0094] At the coronal end 4 of the drill bit 1, which is configured to interact with bone tissue, the shape of the drill bit 1 may be adapted to be substantially the same size as the dental implant in its position when implanted. At the apical end 2, the drill bit 1 may be adapted to be smaller in size than the dental implant. The latter is to enhance the primary stability of the implant by creating a press-fit between the patient's bone tissue and the implant.

[0095] Generally, it is advantageous to adapt the shape of the drill bit 1 along the longitudinal axis L to the geometric shape of the dental implant to be inserted into the bone recess prepared using the drill bit 1. Preferably, this adaptation takes into account the type of bone located adjacent to the implant after implant placement. In particular, in cartilage, the drill bit 1 is smaller relative to the implant to support the anchoring of the implant within the bone tissue.

[0096] The (average) size of the drill bit 1 is essentially the same as that of a dental implant at the coronal end 4, which reduces distortion within the cortical bone tissue after implant placement, prevents bone resorption, and promotes bone invasion.

[0097] By having the drill bit 1 smaller than the dental implant at the apical end 2, good primary stability of the dental implant within the bone recess is achieved.

[0098] The non-circular drill bit core 20 includes at least one compression zone 27 and at least one relaxation zone 28 (see Figure 4).

[0099] In a given rotational direction of the drill bit 1, at least one compression zone 27 begins at the innermost tip 29a with a radial distance r3a from the longitudinal axis L, preferably to the outermost tip 24 along the outline, and extends along a portion of the outline of the cross-section of the drill bit core 20 for a maximum radial distance r1 between the outline and the longitudinal axis L.

[0100] Furthermore, in a given rotational direction of the drill bit 1, at least one relaxation zone 28 begins at the outermost tip 24, which is at a maximum radial distance r1 from the longitudinal axis L, and extends along a portion of the outer contour of the cross-section of the drill bit core 20 to the innermost tip 29b, which has a radial distance r3b from the longitudinal axis L. Distances r3a and r3b may be equal.

[0101] The outline between the innermost tip 29 and the outermost tip 24 of the compression zone 27 and / or relaxation zone 28 is preferably smooth (e.g., simply curved). Nevertheless, either or both of zones 27 and 28 may have at least one straight subsection.

[0102] It should be noted that the cross-sectional outline of a drill bit core having multiple outermost tip sections 24 that are directly adjacent to each other, i.e., forming a circular line section, is also included because all of these outermost tip sections 24 have a first radial distance r1 (maximum radial distance). The same applies to the innermost tip section 29 that is at a minimum radial distance r3 from the longitudinal axis L. Nevertheless, it is preferable to have individual outermost tip sections 24 and / or innermost tip sections 29.

[0103] The number of compression zones 27 within the cross-section of the drill bit core 20 can be roughly equal to the number of relaxation zones 28. In this situation, either or both of the zones 27 and 28 may be interrupted by the cutting zones 45, which are described in more detail below, so the terms are used in general terms.

[0104] In the compression zone 27, the drill bit 1 is configured to compress the bone tissue radially outward, that is, to exert a density-increasing or condensing effect on the bone tissue. As the drill bit rotates, the radial distance of the cross-section of the drill bit core 20 increases from a radial distance r3 to a radial distance r1, so that a given tip (not shown) in the bone tissue is pushed radially outward. This outward movement relative to the bone tissue causes it to condense.

[0105] In the relaxation zone, the drill bit 1 allows compressed bone tissue to recover as the outline 3 of the drill bit core 20 moves radially inward. In other words, as the drill bit rotates, the radial distance of the outline of the drill bit core decreases from the outermost tip 24 to the innermost tip 29, so that a given tip (not shown) in the bone tissue can continue radially inward.

[0106] While we do not wish to be bound by theory, it has been found that bone tissue with higher density, such as cortical bone, generally recovers faster than bone tissue with lower density, such as cancellous bone. In other words, in the relaxation zone of drill bit 1, bone tissue with higher density relaxes and stretches radially inward faster than bone tissue with lower density.

[0107] At least a portion of the outer shape of the cross-section of the drill bit core 20 is preferably non-circular (but preferably rounded or curved). Therefore, at least a portion of the drill bit core 20 along the longitudinal axis L has at least a partially non-circular cross-section.

[0108] The cross-sectional outline of the drill bit core 20 may also be non-circular along the entire extension of the drill bit core 20 along the longitudinal axis L, or at least substantially along the entire extension. For example, the non-circular outline may be oval or trioval. However, other shapes of the non-circular outline, in particular substantially round outlines, are also possible. Nevertheless, and as stated above, the drill bit core 20 may also include a cross-sectional outline that is substantially circular, at least along a portion of the longitudinal axis L.

[0109] A non-circular outline allows for the definition of at least one compression zone 27 and relaxation zone 28. That is, the portion of the outline of the cross-section of the drill bit core 20 from the minimum radial distance r3a to the maximum radial distance r1 in a given rotational direction of the drill bit 1 is defined as a compression zone 27, i.e., it is configured to compress adjacent bone tissue. The portion of the outline of the cross-section of the drill bit core 20 from the maximum radial distance r1 to the minimum radial distance r3b in a given rotational direction of the drill bit 1 is defined as a relaxation zone 28, i.e., it is configured to allow relaxation of previously compressed bone tissue. The shape of the non-circular outline 3 can be designed so that multiple compression zones 27 and relaxation zones 28 are defined along the outline of the cross-section of the drill bit core 20.

[0110] The drill bit 1 may be configured differently from the apical end, where the coronal end 4 has a compact structure and interacts with relatively dense cortical bone tissue, and the apical end generally prepares trabecular structures and generally low-density cancellous bone tissue. Therefore, when preparing the bone recess for insertion of a dental implant, it is possible to prepare these different regions of bone tissue in a single step. In this way, a complex drilling protocol can be avoided in most patients. Preferably, a pilot drill may be used before the drill bit 1 to facilitate preparation.

[0111] The drill bit 1 includes a cutting portion that extends at least partially (preferably along the entire) of the groove 40. Therefore, at least a portion of the groove 40 may be configured as a non-cutting groove, i.e., a groove with an edge that does not form a cutting edge 43.

[0112] The cutting portion may be located along the longitudinal axis L from the apical end 2 to the coronal end 4, substantially along the entire length of the drill bit core 20, i.e., along the portion configured to interact with bone tissue.

[0113] Preferably, the groove 40 extends along the longitudinal axis L along the entire length of the drill bit (working portion). In other words, the first end of at least one groove is at the apical end 2 of the drill bit, and the second end of this groove is at the coronal end of the drill bit, which is configured to interact with bone tissue. The groove 40 may extend continuously between these first and second ends. The drill bit may include two or more grooves having the same characteristics as described above.

[0114] As described above, the cutting portion is preferably tapered towards the apex, that is, the cross-section of the cutting portion perpendicular to the longitudinal axis L decreases in size from the coronal end to the apex. As a result, when the drill bit drills into bone tissue, the cutting portion increases the size of the hole created by cutting the adjacent bone tissue. If guide threads 30 are present, the cutting motion is performed with a specific, stable feed.

[0115] Furthermore, the cutting portion may be configured to condense bone tissue, at least partially or entirely. Thus, the cross-section of such a cutting portion includes a compression zone 27 and a relaxation zone 28. This configuration allows the cutting portion to compress bone tissue in the compression zone 27 and relax bone tissue in the relaxation zone 28 as it rotates in a predetermined rotational direction of the drill bit 1.

[0116] As described above, the contours along the compression zone 27 and the relaxation zone 28, and / or the transition between the compression zone 27 and the relaxation zone 28, are preferably (simply) curved, meaning they may not include straight sections or discontinuities (except for the cutting zone 45). This has a positive effect on the structural integrity of the bone tissue treated by the drill bit 1.

[0117] Nevertheless, at least a portion of the cutting portion or the cutting portion itself may also be configured as a cutting portion without being configured to condense bone tissue by rotation or in the rotational direction. Such a cutting portion is configured without a compression zone 27 and a relaxation zone 28.

[0118] However, the outline of the cross-section of the drill bit core 20 along at least a portion of the overall cutting area or the entire cutting area is preferably non-circular and includes a compression zone 27 and a relaxation zone 28. As a result, the outline is configured to have a condensation effect on bone tissue during rotation. Depending on the configuration of the non-circular outline, multiple compression zones and relaxation zones can be defined along the outline of the cross-section of the drill bit core 20.

[0119] If not configured to condense in the rotational direction, the cross-sectional outline of the drill bit core 20 may be substantially circular. The cross-sectional outline of the cutting portion not configured to condense bone tissue in the rotational direction is substantially circular if a groove 40 and / or guide thread 30 are present.

[0120] Along the outer contour of the cross-section of the cutting portion of the drill bit core 20, the cutting portion preferably includes at least one cutting zone 45, which includes a cutting edge 44. The cutting zone 45 forms a recessed area in the outer contour of the cutting portion and is defined by a groove 40, which includes a cutting edge 43. Thus, the cutting portion includes at least one groove 40. As described above, the groove 40 is preferably formed as a recess or groove extending along the drill bit core 20 within the drill bit core 20. Furthermore, the groove 40 may be straight, but preferably extends spirally around the drill bit core 20. In the latter case, the cutting force is distributed along the circumferential direction of the drill bit 1, facilitating guidance during insertion.

[0121] Preferably, the cutting zone 45, including the blade portion 44, is located within the compression zone 27 of the outline 3 of the cutting portion of the drill bit, which is also configured to condense bone tissue. In this case, the outline of the compression zone 27 is interrupted by the cutting zone 45.

[0122] At least one cutting edge 44 is located at a second radial distance r2 from the longitudinal axis L in a cross-sectional view of the drill bit core 20 along the cutting portion. The outer shape 3 of the cross-section of the drill bit core 20 along the cutting portion may include two or three pairs of outermost tip portions 24 and cutting edges 44, each pair including an outermost tip portion 24 and a cutting edge 44.

[0123] The cutting edge portion 44 preferably represents a discontinuity along the outer contour line 3 of the cutting portion. Therefore, the cutting edge portion 44 includes a relief angle, a lip angle, and a rake angle.

[0124] At least one cutting edge 44 located at a second radial distance r2 enables cutting of bone tissue along a circle in a cross-section having a radius of the second radial distance r2 from the longitudinal axis L. If the second radial distance r2 is smaller than the first radial distance r1 of the outermost tip 24, which will be described in more detail below, the drill bit 1 is not configured to cut bone tissue in a region having a radial distance greater than the second radial distance r2.

[0125] Therefore, the second radial distance r2 may be smaller than the first radial distance r1 of the outermost tip portion 24 in the cross-section of the drill bit core 20 in at least a portion of the cutting portion along the longitudinal axis L, i.e., in at least a portion of the cross-section along the longitudinal axis L. In other words, the drill bit 1 and the cutting portion may include a portion along the longitudinal axis L that has a negative relief angle.

[0126] Alternatively, the first radial distance r1 and the second radial distance r2 may also be substantially equal in at least a portion of the cutting portion along the longitudinal axis L within the cross-section of the drill bit core 20. In other words, the outermost tip 24 and the cutting edge 44 may substantially coincide. In this case, the drill bit 20 and the cutting portion may include a portion along the longitudinal axis where the cutting edge 44 has a positive relief angle.

[0127] The ratio between the first radial distance r1 of the outermost tip portion 24 and the second radial distance r2 of the cutting edge portion 44 may vary for each cross-section of the drill bit core 20 along the cutting portion.

[0128] In one embodiment, where the second radial distance r2 is smaller than the first radial distance r1, the drill bit 1 and the cutting portion include a non-cutting zone 46 in which the drill bit 1 is not configured to cut bone (see cross-section in Figure 4).

[0129] The radial extension of the non-cutting zone 46 defines a ring-shaped region between a second radial distance r2 and a first radial distance r1. Within this non-cutting zone 46, the drill bit 1 is configured to allow alternating compression or relaxation of bone tissue, that is, to apply force to the bone tissue radially without cutting the bone tissue. As described above, in the compression zone 27, bone tissue adjacent to the compression zone is pushed radially outward when the drill bit 1 rotates in a given rotational direction, while in the relaxation zone 28, bone tissue can be restored radially inward.

[0130] While not wishing to be constrained by theory, drill bit 1 utilizes the finding that bone tissue with higher density recovers faster than bone tissue with lower density, i.e., it moves more quickly radially inward. After compressing the bone tissue radially outward within the compression zone 27, the compressed bone tissue recovers radially inward within the relaxation zone 28. Due to the difference in recovery time, drill bit 1 tends to cut through bone tissue with higher density (e.g., cortical bone tissue).

[0131] The time allowed for recovery depends on the circumferential positions of the cutting edge 44 and the outermost tip 24 (as well as the rotation rate and / or rotational speed of the drill bit 1), and therefore the positions of the compression zone 27 and relaxation zone 28 along the outer shape 3 of the cross-section of the drill bit core 20 relative to the cutting edge 44. Within a predetermined allowable recovery time, bone tissue that recovers to a radial distance smaller than the second radial distance r2 is cut by the next cutting edge 44 it passes over, while bone tissue that recovers to the tip between the second radial distance r2 and the first radial distance r1 is not cut by the next cutting edge 44. Thus, the cutting edge 44 cuts bone tissue to different degrees according to its characteristics, that is, hard bone tissue can be cut to a greater extent than cartilage tissue. This effect can be adjusted by the geometric shape of the drill bit core 20, i.e., the size of the first and second radial distances r1 and r2, and their circumferential positions.

[0132] When the second radial distance r2 is substantially equal to the first radial distance r1, the drill bit 1 and the cutting portion have a different cutting behavior than described above. Since the cutting edge 44 and the outermost tip 24 substantially coincide, the cutting edge 44 is located at the outermost radial position. In other words, all other tips on the outer contour of the cross-section of the drill bit core 20 are located more radially inward than the cutting edge 44 (see Figures 5 and 6). Thus, the drill bit 1 is not configured to allow compression or relaxation of bone tissue, but instead cuts bone tissue within a circular region defined by the first radial distance r1 or the second radial distance r2.

[0133] This is structurally illustrated in Figures 5 and 6. In the cross-section of Figure 6, the theoretical outermost tip 24' of the basic outline 25 of the drill bit core 20 (i.e., the outline without considering the guide threads 30 and / or cutting grooves 40), and the outermost tip 24 of the drill bit outline 3 coincide with the cutting edge 44 of the drill bit outline 3.

[0134] Note that when determining the outermost tip 24 of the drill bit's outline 3, the guide threads 30, if present, should not be taken into account (see cross-sections in Figures 4-6). Furthermore, even if a cross-section perpendicular to the longitudinal axis along the cutting portion generally includes a predetermined number of compression zones 27, relaxation zones 28, cutting zones 45, non-cutting zones 46, the outermost tip 24, and / or cutting edge 44, a particular cross-section may not include all of these features due to the influence of other structural features of the drill bit 10, particularly the guide threads 30 (see Figure 4, which lacks a portion of one relaxation zone and one compression zone due to the guide threads 30).

[0135] Referring to Figure 6, the theoretical outermost tip 24' of the basic outline 25 of the drill bit core 20 is located along the cutting zone 45 where the groove 40 along the outline 3 of the drill bit 1 is formed. Therefore, the theoretical outermost tip 24' does not coincide with the outermost tip 44 of the outline 3 of the drill bit. However, even in this case, the outermost tip 24 coincides with the cutting edge 44.

[0136] Note that the cross-section in Figure 6 does not include either the compression zone 27 or the relaxation zone 28. Part of the outline corresponds structurally to the relaxation zone 28, but in terms of its functional configuration, it cannot function as a relaxation zone. In other words, the outline 3 lacks a compression zone 27 that has the function of compressing bone tissue, so that there is no relaxation zone 28 that would allow for the relaxation of bone tissue previously compressed by the compression zone 27 of the drill bit 1.

[0137] Those skilled in the art will understand from the above description that the cutting behavior of the drill bit 1 changes with a change in the ratio between the first radial distance r1 and the second radial distance r2. Therefore, it is possible to adjust the cutting behavior of the drill bit 1 along the longitudinal axis L, taking into account different regions in the depth direction of the bone tissue at the implant site.

[0138] Preferably, the cutting portion includes a first portion along the longitudinal axis L, and the second radial distance r2 of the cutting edge 44 is smaller than the first radial distance r1 of the outermost tip 24. In this first portion, the cutting portion may include a negative relief angle at the cutting edge 14. Furthermore, the first portion of the cutting portion may also be configured to condense bone tissue during rotation. As a result, the cross-sectional outline of the first portion of the cutting portion preferably includes at least one compression zone 27 and at least one relaxation zone 28.

[0139] The cutting portion may further include a second portion. In the second portion of the cutting portion, the second radial distance r2 may be substantially equal to the first radial distance r1. The second portion of the cutting portion may further include a cutting edge 44 having a positive relief angle. Preferably, the first portion of the cutting portion is positioned at the top end of the second portion of the cutting portion.

[0140] The cutting behavior of the first and second parts of the cutting area differs from that of the second part due to the difference in the ratio between the first radial distance r1 and the second radial distance r2 between them.

[0141] In particular, the outline of the first portion of the cutting area is configured such that, as the drill bit rotates, it compresses the bone tissue in the compression zone 27, allows the bone tissue to relax in the relaxation zone 28, and then cuts the bone tissue with the cutting edge 44 in the cutting zone 45. As a result, the amount of bone tissue cut during rotation depends on the relaxation characteristics of the bone tissue, that is, how much and how quickly the bone tissue relaxes after being compressed.

[0142] While we do not wish to be bound by theory, the inventors have observed that cancellous bone with relatively low bone density is not removed as much. Therefore, more cartilage tissue remains to support the dental implant being inserted.

[0143] The second portion of the cutting section is not configured to compress bone tissue during rotation, but instead cuts bone tissue at the outermost tip 24 corresponding to the blade 44.

[0144] While we do not wish to be bound by theory, this feature is advantageous in cortical bone with relatively high bone density, where the effects of further bone tissue condensation are less pronounced. Therefore, the second portion preferably creates a bone recess within the cortical region of bone tissue having a size substantially corresponding to the size of the dental implant to be implanted, in order to avoid bone resorption and, consequently, faster penetration of the dental implant.

[0145] In a given rotational direction of the drill bit 1, the cutting edge 44 along the first portion may be positioned along the outline of the cross-section of the drill bit such that, during rotation, the cutting edge 44 passes in front of the outermost tip 24, or simultaneously with the outermost tip 24, the bone tissue location. After the relative positions of the outermost tip 24 and the cutting edge 44 change along the outline so that they correspond to each other, the theoretical outermost tip 24' may continue to change its relative position so as to pass the bone tissue location in front of the cutting edge. This results in a continuous change in the relief angle from a negative relief angle to a positive relief angle.

[0146] As described above, the cutting behavior of the drill bit 10 is determined by the geometric shape of the drill bit 1, and in particular the magnitudes of the first and second radial distances r1 and r2, and their circumferential positions.

[0147] As described above, the cutting groove may extend spirally around the drill bit 1. As a result, the cutting portion 44 also extends spirally around the drill bit 1, particularly by a first pitch. The first pitch may be the same as the pitch of the cutting groove 15 (a cutting groove of constant size), or it may be different from the pitch of the cutting groove (a cutting groove of varying size). In particular, the first pitch may be smaller than the pitch of the cutting groove (i.e., the size of the cutting groove increases in the apex-crown direction).

[0148] Due to the change in cutting behavior, the outermost tip portion 24 of the cross-section of the drill bit core 20 along the longitudinal axis L may be located along a helical line by a second pitch around the longitudinal axis L. Alternatively, the outermost tip portions 24 of these cross-sections may also be located along a substantially straight line preferably arranged parallel to the longitudinal axis L.

[0149] Preferably, the first and second pitches of the blade portion 44 and the outermost tip portion 24 are different from each other. In particular, the first pitch is smaller than the second pitch. Alternatively, the first and second pitches may be substantially equal.

[0150] In one embodiment where the first pitch and the second pitch are different from each other, the relative circumferential positions of the outermost tip portion 24 and the cutting edge portion 44 change along the longitudinal axis L of the cutting portion of the drill bit 1. Therefore, it becomes possible to continuously adjust the cutting behavior of the drill bit 1 along the longitudinal axis L for different bone regions.

[0151] The drill bit 1 according to this disclosure makes it possible to reduce the complexity of the drilling protocol. Thus, it is possible to avoid the sequential use of multiple different tools and complex drilling protocols, and to more easily prevent misalignment of tools used sequentially. Furthermore, the drill bit 1 makes it possible to prevent the size of the formed bone recess from becoming too large or too small. [Explanation of symbols]

[0152] The following is a list of reference numerals used in the descriptions and drawings. These reference numerals refer to features that have the same or equivalent function and / or structure throughout the drawings. 1 Drill Bit 2 Top end 3 Outline 4. Coronal end of the bone interaction region 10. Rake face at the apex 11 Central area 12 Radially extended portion of the arm shape of the rake face at the apex 14. Circumferential edge of the rake face at the apex. 14a Tip of the arm on the rake face at the apex 14b Side edge of the arm of the apical rake face 14c Side edge opposite the arm of the apical rake face 20 Drill Bit Cores 21. Circumferential surface of drill bit core 22 Top edge of drill bit core 23 Chamfered section 24 Outermost tip 24' Theoretical outermost tip 25 Basic outline of drill bit core 27 Compression Zones 28 Relaxation Zones 29 Innermost tip 30 guide threads 40 grooves 41 Concave 42. Top edge of concave surface 43 cutting edge 44 Blade 45 cutting zones 46 Non-cutting zones 50 Retaining Arms r1 First radial distance r2 Second radial distance r3 Minimum radial distance L Longitudinal axis

Claims

1. A drill bit (1), wherein the drill bit (1) is Apical end (2), coronal end, and longitudinal axis (L) extending between the apical end and the coronal end, A drill bit core (20) extending along the longitudinal axis (L), At least two grooves (40), each groove being defined by a concave surface (41) that forms a recess along the drill bit core (20), and The top end scoop face (10) located at the top end (2), Includes, The top edge (42) of the concave surface (41) and the top edge (22) of the drill bit core (20) define the shape of the top rake face such that the top rake face defines the contour of the retaining arm (50) on the top end (2), and each retaining arm is formed between the concave surfaces of adjacent grooves (40). At least one of the two grooves (40) extends along the longitudinal axis of the drill bit (1) over the entire length of the portion of the drill bit (1) configured to interact with bone tissue.

2. A drill bit (1), wherein the drill bit (1) is Apical end (2), coronal end, and longitudinal axis (L) extending between the apical end and the coronal end, A drill bit core (20) extending along the longitudinal axis (L), At least two grooves (40), each groove being defined by a concave surface (41) that forms a recess along the drill bit core (20), and The top end scoop face (10) located at the top end (2), Includes, The top edge (42) of the concave surface (41) and the top edge (22) of the drill bit core (20) define the shape of the top rake face such that the top rake face defines the contour of the retaining arm (50) on the top end (2), and each retaining arm is formed between the concave surfaces of adjacent grooves (40). The drill bit further includes a cutting portion extending along the entirety of at least one of the at least two grooves (40), wherein the cutting portion is located along the longitudinal axis (L) of the drill bit core (20) from the apical end (2) to the coronal end of the portion of the drill bit configured to interact with bone tissue.

3. The drill bit (1) according to claim 1 or 2, further comprising at least one guide thread (30) protruding from the drill bit core (20) and extending spirally along the drill bit core (20), wherein the guide thread (30) is preferably tapered toward the apex.

4. The drill bit (1) according to claim 3, wherein the radial height of the guide thread (30) is smaller than the radial extension of the contour of the retaining arm at the top end rake face (10).

5. The drill bit (1) according to claim 3 or 4, wherein the guide thread (30) has a non-circular circumferential profile, and the non-circular circumferential profile is preferably a tri-oval profile.

6. Each retaining arm (50) has a radial extension that is larger than its circumferential width, according to any one of claims 1 to 5, the drill bit (1).

7. The drill bit (1) according to any one of claims 1 to 6, wherein the circumferential edge (14) of the rake face (10) of the top end is arranged in a plane perpendicular to the longitudinal axis (L).

8. The drill bit (1) according to any one of claims 1 to 7, wherein the drill bit core (20) has a non-circular contour in a cross section perpendicular to the longitudinal axis (L), and in the longitudinal direction of the drill bit (1), the non-circular contour rotates about the longitudinal axis (L) to preferably create a non-circular twisted drill bit core.

9. The drill bit (1) according to any one of claims 1 to 8, wherein the drill bit core (20) is tapered toward the apical end (2).

10. The drill bit (1) according to any one of claims 1 to 9, wherein the concave surface (41) of each groove (40) and the circumferential surface (21) of the drill bit core (20) form a cutting edge (43).

11. The drill bit (1) according to any one of claims 1 to 10, wherein at the top edge of each concave surface (41), the concave surface and the top end rake face (10) partially form a cutting edge, the cutting edge having a forward rake angle and substantially no forward relief angle.

12. The drill bit (1) according to any one of claims 1 to 11, wherein the at least two grooves (40) extend spirally along the drill bit core (20).

13. The drill bit (1) according to claim 8, dependent on claim 5, wherein the non-circular contour of the drill bit core (20) and the non-circular circumferential contour of the guide thread (30) are formed to have a circumferential offset.

14. A method for performing an osteotomy using a drill bit (1), particularly the drill bit described in any one of claims 1 to 13, Drilling a hole with a pilot drill, The size of the hole is increased for inserting a dental implant using the drill bit (1), wherein the drill bit comprises a drill bit core (20), at least two grooves (40), each groove defined by a concave surface (41) that forms a longitudinal recess along the drill bit core (20), a apical rake face (10) at the apical end (2) of the drill bit, and a retaining arm (50) extending crown-shaped from the apical rake face, each retaining arm formed between the concave surfaces of adjacent grooves (40). Includes, A method wherein, when the bottom of the hole drilled by the pilot drill comes into contact with the top end rake face (10), the retaining arm (50) generates a braking force to stop the rotation of the drill bit (1).

15. The method according to claim 13, wherein the tip of the pilot drill has a diameter larger than the diameter of the rake face (10) at the top end.

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