Tool for fixing a probe in a dental implant

Abstract

The invention relates to a tool for screwing an ultrasonic probe into a dental implant which is fixed in the bone of a patient's mouth, the tool comprising a body comprising a proximal portion (111) and a distal portion (112), the proximal portion (111) of the body comprising a gripping interface or handle (1110) allowing a practitioner to grip the body by hand in order to apply a rotational moment thereto about a longitudinal axis (A) of the body, the distal portion (112) of the body comprising a deformable portion (1120) suitable for engaging with the head of the probe and surrounding a central cavity (E) which is centered on the longitudinal axis of the body.

Description

[0001] "Probe fixation tool for a dental implant"

[0002] TECHNICAL FIELD OF THE INVENTION

[0003] The invention relates to a tool for screwing a dental prosthetic element.

[0004] The term "dental prosthetic component" refers to any element that makes up a dental prosthesis, as well as any piece of equipment or instrumentation used to place, adjust, check, maintain, or remove a dental prosthesis. Examples include: an implant abutment, whether permanent or temporary, angled or straight, multi-unit or single-unit; a screw, whether a healing screw, a closure screw, or a prosthetic screw that secures prosthetic components to a dental implant or implant abutment; an impression transfer device; or a sensor. For the sake of brevity, a dental prosthetic component is also referred to as a "prosthetic component" in this document.

[0005] A tool according to the invention allows a dental prosthetic element to be screwed, typically into the internal connection of a dental implant.

[0006] STATE OF THE ART

[0007] Probes used to monitor the stability of a dental implant fixed in a patient's oral bone are examples of dental prosthetic devices. US patent document 2023240816 A1 describes one such probe. This probe is designed to be coupled to a dental implant and to monitor the implant's stability through resonance frequency analysis.

[0008] Patent document WO 2019 / 201888 A1 describes another example of a probe and a device using such a probe. This probe is adapted to be coupled to the implant, to emit an ultrasonic wave that propagates inside the implant, and to collect the reflected ultrasonic wave. The stability of the implant is checked by measuring and analyzing the reflected ultrasonic wave. When the probe is coupled to the implant by screwing it into the implant, it is important, for the reliability of the reflected ultrasonic wave measurement, that the screwing of the probe into the implant be carried out with precise control of the tightening torque.

[0009] In general, most dental prosthetic elements that need to be screwed in must be screwed in with precise control of the tightening torque.

[0010] Traditionally, the screw is tightened by a practitioner (typically a dentist) using a torque wrench. The practitioner uses the torque wrench manually, engaging it with one end of the prosthetic component (e.g., in the case of a probe, with the probe head). The practitioner then tightens the prosthetic component into the implant by manually turning the torque wrench. The torque wrench is designed to stop applying torque to the prosthetic component, i.e., to "disengage," when the applied torque reaches a threshold value. This threshold value determines the tightening achieved and corresponds to the desired tightening torque, or "target torque." In practice, the target torque is often that recommended by the prosthetic component manufacturer.

[0011] Although widespread, the use of a torque wrench is not entirely satisfactory because it requires numerous precautions. In particular, before each surgical procedure, the torque wrench must be disassembled, cleaned, sterilized, and then reassembled. These various steps are complex and time-consuming due to the number of parts that make up the wrench and their arrangement. Moreover, if these steps are not carried out correctly, they can lead to a malfunction of the wrench, especially regarding the setting of the target torque. Because of this very real risk, torque wrench manufacturers recommend a test to verify the correct assembly and proper functioning of the wrench before each procedure.

[0012] Furthermore, while the torque wrench allows for a certain degree of control over the tightening of the dental prosthesis, this control could be improved. In particular, the reproducibility of the tightening—that is, ensuring that the same tightening torque is achieved with each tightening operation—could be enhanced.

[0013] Furthermore, the positioning (orientation, tilt) and manipulation of the torque wrench in a patient's mouth can be tricky in certain situations. To address this issue, US patent document 2023240816 A1 proposes equipping the wrench with an extension bar. However, this solution further increases the number of parts to assemble and clean.

[0014] Finally, due to the number of parts composing torque wrenches and their arrangement, the manufacturing cost of a torque wrench is relatively high.

[0015] There is therefore a need for a new screw-driving tool that is easy to use and that can, at least in part, overcome the disadvantages of torque wrenches.

[0016] SUMMARY OF THE INVENTION

[0017] According to a first aspect, the invention relates to a tool for screwing a dental prosthetic element. The tool comprises a body having a proximal part and a distal part fixed to the proximal part. The proximal part of the body includes a rotational drive interface to allow a driving torque to be applied to the body around a longitudinal axis of the body.

[0018] The distal part of the body comprises: a central cavity centered on the longitudinal axis and adapted to receive one end of a dental prosthetic element, and a deformable part surrounding the central cavity and adapted to engage with the end of the prosthetic element introduced into the central cavity and ensure a rotational connection around the longitudinal axis between the body and the dental prosthetic element, so as to transmit the driving torque to the prosthetic element.

[0019] The deformable portion is capable of elastic deformation, releasing the rotational connection when the driving torque transmitted to the prosthetic element by the distal part of the body exceeds a threshold value called the "release value." This release value corresponds to the target tightening torque. In other words, when the driving torque exceeds the release value, the rotational connection between the body and the prosthetic element is interrupted (this will be referred to as "disengagement"). Thus, the driving torque cannot exceed the release value.

[0020] The deformation of the deformable part is elastic, and therefore reversible: the deformable part returns to its initial shape when the reaction forces applied by the prosthetic element on the deformable part disappear. In some embodiments, the deformable part returns to its initial shape when the rotation of the tool is continued after disengagement. This provides a haptic sensation of "no tightening," described in detail below, which alerts the practitioner that the target tightening torque has been reached and that it is no longer necessary to rotate the tool.

[0021] Thus, the tool of the invention performs the same disengagement function as a torque wrench but with a different, simpler structure. In particular, this tool can be a single piece or made up of a small number of parts, which facilitates assembly and cleaning and reduces its manufacturing cost.

[0022] According to a second aspect, the invention relates to a tool for screwing a dental prosthetic element, the tool comprising: a body having a proximal portion and a distal portion integral with the proximal portion, and a screw tip having a connecting end adapted to engage with the distal portion of the body and a profiled end adapted to engage with a dental prosthetic element. The proximal portion of the body includes a rotational drive interface to allow a driving torque to be applied to the body about a longitudinal axis of the body.The distal part of the body comprises: a central cavity centered on the longitudinal axis and adapted to receive the connecting end of the screw tip, and a deformable part surrounding the central cavity and configured to engage with the connecting end introduced into the central cavity and ensure a rotational connection around the longitudinal axis between the body and the screw tip so as to transmit the driving torque to the screw tip, the screw tip in turn transmitting this driving torque to the dental prosthetic element.

[0023] The deformable part is capable of elastic deformation, releasing the rotational connection when the driving torque transmitted from the distal end to the screwdriver bit exceeds a release value. In other words, when the driving torque exceeds the release value (i.e., the target tightening torque), the rotational connection between the body and the screwdriver bit is interrupted (i.e., disengagement occurs). The deformation of the deformable part is elastic and therefore reversible: the deformable part returns to its initial shape when the reaction forces applied by the screwdriver bit on the deformable part disappear.

[0024] The profiled end of the screw bit is designed to engage with a corresponding impression or profile on the prosthetic component, ensuring efficient torque transmission for screwing and tightening. The profiled end may have a flat, cruciform, star, square, hexagonal, or manufacturer-specific profile or impression.

[0025] The tool may include a plurality of interchangeable screw tips having connecting ends that can be inserted into the central cavity of the tool body, and profiled ends of different sizes and / or shapes. This allows the same tool body to be used with several screw tips, the screw tip being chosen according to the prosthetic element to be screwed.

[0026] In some embodiments, the rotational drive interface is a gripping interface, in particular a knurled knob, allowing a practitioner to grasp the tool body by hand in order to apply the driving torque. This direct manipulation of the tool body by the practitioner simplifies the tool's use.

[0027] In other embodiments, the rotational drive interface is a coupling interface with a handle or a wrench. However, this wrench does not need to be a torque wrench, as the disengagement function is provided by the deformable part of the body.

[0028] The rotational drive interface can have a geometry that allows it to function as both a coupling interface and a gripping interface. This is the case, for example, with a drive interface having a polygonal (e.g., hexagonal) cross-section.

[0029] In some embodiments, the deformable portion of the body comprises one or more elastically deformable tabs, each having an inner face. This inner face is adjacent to the central cavity and extends parallel to the longitudinal axis of the body when the tab is at rest. This tab or these tabs cooperate with one or more contact surfaces formed on the end of the prosthetic element or on the connecting end of the screw tip inserted into the central cavity of the body.

[0030] In some embodiments, the deformable portion comprises several elastically deformable tabs distributed around the longitudinal axis of the body to form a ring of tabs around the central cavity, each tab being separated from each of its adjacent tabs by a groove. Each tab is connected to the rest of the tool body by its proximal portion and is free in its distal portion. The elastic deformation of the deformable portion then corresponds to the separation of the distal portion of the tabs from the longitudinal axis.

[0031] In some embodiments, the inner faces of the tabs define a polygonal indentation with, for example, between 3 and 12 sides. For example, the indentation may have a hexagonal or octagonal cross-section. In other embodiments, the inner faces of the tabs define a circular indentation.

[0032] In some embodiments, the tool includes a protruding lug in the central cavity, positioned parallel to the longitudinal axis. The lug acts as a stop in this direction for the prosthetic element or screw head inserted into the central cavity. The body and the lug can be formed as a single piece, for example, by molding. Alternatively, the lug can be removable, allowing the body and lug to be manufactured separately.

[0033] In some embodiments, the body and the lug are made of two different materials. The body must have a deformable portion, whereas deformation of the lug is not required. The lug can therefore be made of a more rigid material than the body.

[0034] In some embodiments, the tool comprises a plurality of interchangeable lugs of different sizes, each of which can be fixed to the bottom of the central cavity. The height of the lug, measured parallel to the longitudinal axis from the bottom of the central cavity, determines the depth of engagement of the prosthetic element or screw tip within the central cavity. Changing the lug allows the depth of engagement to be varied.

[0035] In some embodiments, the tool body is made of plastic, particularly polyphenylsulfone (PPSU), polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK), or another polymer with mechanical properties that allow the desired elastic deformation of the deformable portion of the body. In other embodiments, the tool body may be made of metal, at least on the inner face of the tabs, which helps to limit their wear (this wear issue does not arise for a single-use tool). The material chosen may also be resistant to high temperatures and humidity to allow for sterilization in an autoclave.

[0036] The invention also relates to an assembly comprising a tool as previously described and a dental prosthetic element. This prosthetic element comprises a first end adapted for engagement in the central cavity of the body or with the profiled end of the screw tip, and a second end adapted for screwing into a dental implant or implant abutment. The tool is used to screw the prosthetic element to a predetermined tightening torque (or target torque) corresponding to the release value.

[0037] In some embodiments, the first end adapted to engage with the deformable part of the body has a polygonal cross-section. This first end then includes edges, which correspond to the vertices of the polygonal cross-section. These edges may be more or less sharp (e.g., chamfered).

[0038] In some embodiments, the edges of the first end and the grooves of the deformable portion of the tool body are such that the edges can engage in the grooves when the body is rotated about the first end. This rotation is possible after the rotational linkage has been released (i.e., after disengagement). Thus, when the tool continues to rotate after disengagement, a haptic sensation of "no tightening" is produced, described in detail below, which alerts the user that the target tightening torque has been reached and that further rotation of the tool is no longer necessary.

[0039] The aims, objects, features, and advantages of the invention will become clearer upon reading the detailed description that follows. This detailed description refers to the accompanying drawings.

[0040] BRIEF DESCRIPTION OF THE FIGURES

[0041] The accompanying drawings are schematic representations of principle, intended to facilitate understanding of the invention, and are not necessarily to scale with practical applications. In the accompanying figures, identical or similar elements (or parts of elements) are identified by the same reference numerals from one figure to another.

[0042] Figure 1 depicts a medical device comprising a handpiece and an ultrasound probe, with a partial enlarged view showing the application of a handpiece connector to the probe head.

[0043] Figure 2 represents a dental implant fixed in the bone of a patient's mouth, an ultrasonic probe screwed into the implant, and a tool according to an exemplary embodiment of the invention.

[0044] Figure 3A shows the tool from Figure 2 in perspective, in an unassembled state.

[0045] Figure 3B shows the tool from Figure 2 in its assembled state, in top view.

[0046] Figure 3C shows the tool of figure 2 in its assembled state, viewed from below.

[0047] Figure 3D represents the tool from Figure 2 in its assembled state, viewed from the side.

[0048] Figure 3E represents the tool of Figure 2, in axial section along plane AA located on Figure 3D, plane AA containing the longitudinal axis A of Figure 2.

[0049] Figure 4 represents a tool according to another embodiment of the invention.

[0050] Figure 5A schematically represents a test setup for measuring the tightening torque obtained using a torque wrench.

[0051] Figure 5B schematically represents a test installation for measuring the tightening torque obtained using a tool according to the invention.

[0052] Figure 6 represents a tool according to another embodiment of the invention.

[0053] DETAILED DESCRIPTION OF THE INVENTION

[0054] Examples of tools for screwing a dental prosthetic element are described in detail below. These examples illustrate the features and advantages of the invention, but the invention is not limited to these examples.

[0055] Figure 1 shows a device comprising a handle or handpiece P with a tip P1. This device also includes an ultrasonic probe S, which is screwed into an implant I. The implant I is fixed in the bone (not shown in Figure 1) of a patient's mouth. The probe S is screwed into the implant to measure its stability in the bone, as explained below. The handpiece P contains means for generating an output signal (e.g., an electrical pulse), means for receiving and processing an incoming electrical signal, a memory for storing this incoming signal, and a display P2 for displaying a measurement result processed by the processing means. The tip P1 of the handpiece includes at its distal end a connector P11, which is connected to the means for generating the output signal and to the means for receiving an incoming signal. This connector P11 can be brought into contact with the probe S to activate it.The probe S includes means (e.g., an ultrasonic transducer) for converting an electrical signal received from connector P11 into an ultrasonic signal and for transmitting this ultrasonic signal to implant I. The probe S also includes means (e.g., the same ultrasonic transducer) for collecting the ultrasonic signal reflected by implant I. Connector P11 is capable of receiving, upon contact with the probe, an incoming electrical signal that is representative of the ultrasonic signal reflected in response to the ultrasonic signal emitted by the probe, and of transmitting this electrical signal to the processing means. The processing means are configured to derive a measure of implant stability from this incoming electrical signal. Display P2 is capable of displaying this implant stability measure.

[0056] Figure 2 illustrates an implant I fixed in the bone of a patient's mouth, a probe S screwed into the implant to measure its stability in the bone, and an example of a screw tool 10. The left side of this figure shows the three parts (implant, probe, and tool) assembled in a position allowing the probe to be screwed into the implant I using the tool 10 (the implant I having been previously screwed into the bone). The right side of this figure shows the probe S and the screw tool 10. The probe S is taken here as an example of a dental prosthetic element within the meaning of the invention. The following explanations, relating to the interaction between the probe S and the screw tool 10, are therefore not limited to a single probe and can be applied to other screwable dental prosthetic elements.

[0057] The probe S has a first end, called the "head" S1, and a second end S2 equipped with fastening means, such as a thread, adapted for screwing the probe S into the implant I. The implant I has a complementary internal thread for this purpose. The head S1 has a polygonal cross-section. It therefore has lateral faces 60 corresponding to the sides of the polygonal cross-section and edges 62 between the lateral faces 60. In the example in Figure 2, the head S1 is a raised hexagonal head with six lateral faces 60 and six edges 62.

[0058] The screw tool 10 includes a body 11 with a proximal part 111 and a distal part 112. The tool 10 also includes a central lug 12 that can be fixed to the body 11.

[0059] The proximal part 111 of the body includes a rotational drive interface 1110 to allow a drive torque to be applied to the body 11 about a longitudinal axis A of the body. "Drive torque" refers to a torque moment or a force moment causing rotation about the longitudinal axis A.

[0060] In this exposition, the direction of the longitudinal axis A is referred to as the "longitudinal direction". Furthermore, unless otherwise specified, the section of an element refers to the section of that element in a plane perpendicular to the longitudinal axis A.

[0061] In this example, the drive interface 1110 is a gripping interface, specifically a knurled knob, allowing a practitioner to grasp the body 11 by hand in order to apply a driving torque. The knob has a polygonal cross-section, more precisely octagonal. However, it could have a different shape. This knob allows a user to position the tool 10 on the head S1 of the probe S and to manipulate the tool 10 to apply a driving torque to the probe S directly by hand, that is, without using a wrench. Furthermore, the body 11 has a narrowing 110 between its distal part 112 and the drive interface 1110. This allows for a good grip on the drive interface 1110 by the practitioner, as this drive interface 1110 protrudes from the proximal part 111.

[0062] In the screwing position, the distal part 112 of the body is positioned on the head S1 of the probe S as shown on the left side of Figure 2. In this screwing position: the longitudinal axis A of the body 11 of the tool 10 is aligned with the longitudinal axis A of the probe, and the probe S is fixed to the body 11 in rotation, around the longitudinal axis A. More precisely, the distal part 112 of the body 11 grips the head S1 of the probe so as to be able to rotate it around the longitudinal axis A.

[0063] When the body 11 is positioned on the probe S and manipulated, via the drive interface 1110, by applying a driving torque around the axis A, as indicated by arrow T, the torque is transmitted to the probe S through the coupling of the distal part 112 of the body with the probe head S1. The probe S is thus rotated to be screwed and then tightened into the implant I.

[0064] The distal portion 112 of the body, as shown in the examples in the figures, comprises a peripheral ring C surrounding a central cavity 20. The ring C forms a deformable portion 1120 of the body 11. The central cavity 20 is centered on the axis A. The shape of this cavity 20 is such that the head S1 can be inserted into it. The engagement of the ring C with the head S1 allows the body 11 and the probe S to be rotationally linked.

[0065] Furthermore, the bottom of cavity 20 (said bottom being at the top of cavity 20 in the figures) constitutes for the head S1 of the probe a stop which allows control of the depth of engagement (according to the longitudinal direction) of the head S1 of the probe in cavity 20.

[0066] The desired release value depends, in particular, on the type of dental prosthesis to be screwed in and the element into which it is screwed. Generally, this release value is on the order of a few N·cm (Newton-centimeters) to a few tens of N·cm. More specifically, it can range from 3 to 40 N·cm. In the case of an ultrasonic probe, this release value can range from 3 to 9 N·cm and, for example, be 5 N·cm.

[0067] In the examples in the figures, the deformable portion 1120 comprises tabs 1121. Each tab 1121 has an inner face 22, adjacent to the central cavity 20. Each tab 1121 of the ring C is separated from each of its neighboring tabs by a groove 1122. Each tab 1121 is free in its distal portion and fixed to the rest of the body 11 by its proximal portion, which forms a pivot joint. Each tab 1121 is elastically deformable in that it can pivot about its proximal portion, its distal portion moving away from the longitudinal axis A under stress and returning to its initial shape by moving towards the longitudinal axis A when the stress is removed. The distal portion 112 of the body 11 is made of a material that allows the elastic deformation of the tabs 1121. In the example in the figures, the distal part 112 comprises six tabs 1121.

[0068] At rest, that is, when no stress is exerted on the tabs 1121, the inner faces 22 of the tabs 1121 (i.e., the faces facing the longitudinal axis A) extend parallel to the longitudinal axis A and define a circular indentation E (see Figures 3C and 3E). This indentation E corresponds to the portion of the central cavity 20 in which the head S1 is housed. At rest, the diameter D1 of the indentation E is smaller than the diameter D2 of the head S1 of the probe S. The diameter D2 is the diameter of the circle circumscribed about the largest cross-section of the head S1. In this case, in the example, the diameter D2 is the diameter of the circle passing through the edges 62, as shown in Figure 2. Since the diameter D2 is greater than the diameter D1, the head S1 is forced into the recess E and the tabs 1121 deform elastically, from their rest position, moving away from the longitudinal axis A.The head S1 is thus clamped between the tabs 1121. In other words, due to its elasticity, each tab 1121 exerts a normal force N (i.e. perpendicular to the longitudinal axis A) on the head S1.

[0069] During the rotation of the body 11, frictional forces are exerted between the tabs 1121 and the head S1. The frictional force exerted by each tab 1121 on the head S1 has a normal component, corresponding to the normal force N, and a tangential component T. The tangential component T results from the driving torque applied to the body 11. The frictional coupling between the tabs 1121 and the head S1 ensures the transmission of the driving torque to the head S1. As the driving torque applied to the body 11 increases, the tangential component T increases, and the transmitted torque increases. This increase continues until the driving torque reaches a threshold value, or release value, corresponding to a limit value T1 of the tangential component T, beyond which the tab 1121 no longer adheres to the head S1 but slides on it.Coulomb's law states that the limiting value T1 is proportional to the normal force N. By controlling the normal force N, one controls the limiting value T1 and therefore the release value. In practice, for tabs 1121 made of a given material, the normal force N, and thus the release value, depends on the geometry of the tabs 1121, in particular their radial thickness e, the difference Dif between the diameter D2 of the head S1 and the diameter D1 of the recess E (Dif = D2 - D1), and the engagement depth P1 of the head S1 between the tabs 1121 along the longitudinal axis A. Some of these measurements are shown in Figure 3E. An increase in the thickness e, the diameter difference Dif, or the engagement depth P increases the normal force N, and therefore the release value.

[0070] The release force is determined based on the dental prosthetic component to be screwed in and the component into which it is screwed. Generally, this release force ranges from a few N·cm (Newton-centimeters) to a few tens of N·cm. More specifically, it can range from 3 to 40 N·cm. In the case of an ultrasonic probe, this release force can range from 3 to 9 N·cm and, for example, be 5 N·cm.

[0071] By way of example and with reference to Figure 3E, the dimensions of the body 11 are as follows. The rotational drive interface 1110 is octagonal with eight faces and eight edges distributed around the longitudinal axis A. The drive interface 1110 has a height along the longitudinal direction of between 2 and 10 mm, for example, 4 mm, and the distance between two opposite edges is 6.5 mm. This drive interface 1110 serves as a gripping interface and can be grasped between the practitioner's thumb and forefinger to apply the driving torque to the body 11. Again by way of example and with reference to Figure 3E, the distal portion 112 has a height of between 2 and 10 mm along the longitudinal direction, for example, 5.35 mm, with tabs 1121 having a height of 5 mm. The lug 12 protrudes by 2 mm (in the longitudinal direction) into the central cavity 20, so that the engagement depth P is equal to 3 mm.The inner diameter D1 of the cavity E is equal to 6.35 mm. The outer diameter of the ring C formed by the tabs 1121 is equal to 8.85 mm, i.e. a thickness e of the tabs 1121 equal to 1.25 mm.

[0072] The diameter D2 of the head S1 can be 6.70 mm, so the diameter difference Dif (= D2 - D1) is 0.35 mm. In the example, the head S1 has a hexagonal cross-section with six faces 60 and six edges 62 distributed around the longitudinal axis A. In this case, the diameter D2 of the head S1 corresponds to the distance between two opposite edges 62 (see Figure 2). The cross-section of the head S1 could, however, have a different shape, including a circular shape, as long as its diameter D2 is greater than the diameter D1 so as to achieve clamping of the head S1 between the tabs 1121 and the transmission of the drive torque by friction, as previously described.

[0073] Figures 3A to 3E show in more detail the tool 10 comprising the body 11 and the lug 12. Figure 3A shows the body 11 and the lug 12 side by side, with the lug 12 not mounted in the body 11. Section AA of Figure 3E represents the tool assembled and ready for use. The lug 12 is fixedly assembled with the body 11. For example, the lug 12 is press-fitted into a central recess 1111 which extends around the longitudinal axis A. The lug 12 is thus integral with the body 11. The lug 12 has a cylindrical proximal portion 121 mounted in the recess 1111. The lug 12 also has a distal portion 122. When the lug 12 is mounted in the body 11, the distal portion 122 of the lug protrudes into the central cavity 20 in the longitudinal direction and thus forms a stop (in the direction of axis A) for the head S1 of the probe S when the latter is inserted into the central cavity 20.The distal portion 122 of the lug can be, as shown in Figure 3E, wider than the proximal portion 121 of the lug in order to form a shoulder 1220 which helps to maintain the lug 12 in position within the body 11, even when the probe head S1 presses against the distal portion 122 of the lug. Controlling the depth of insertion of the probe head S1 into the cavity 20 by the lug 12 helps to control the engagement depth P1 of the probe head S1 between the tabs 1121 and thus the release value, as explained previously.

[0074] To screw a probe S into an implant I using a tool 10 as shown in the figures, the screwing procedure is, for example, as follows. The probe S is screwed lightly into the implant by the practitioner using a finger. The practitioner then takes the tool 10 and forces it onto the head S1 of the probe S. Alternatively, the tool 10 is first forced onto the head S1, and then the practitioner manually screws the probe-tool assembly into the implant. The forced insertion of the tool 10 results in a radial outward deformation of the tabs 1121 (i.e., away from the longitudinal axis A), as the tabs 1121 are pushed by the edges 62 of the head S1. The practitioner then rotates the tool 10 by holding it by the drive interface 1110 until the drive torque which he applies to the tool 10 reaches the release value, which results in the sliding of the tabs 1121 on the head S1 and therefore the "disengagement".

[0075] Figure 4 shows another embodiment of tool 10. The cross-section in the upper right of the figure is a longitudinal section along plane BB passing through longitudinal axis A. According to this cross-section, from the proximal to the distal end of tool 10 (i.e., from top to bottom in the figure), the body 11 comprises the following parts: a proximal part 111, a transition part 115, and a distal part 112. The proximal part 111 comprises a first part forming a rotational drive interface 1110 and a second part 1113. The transition part 115 forms a frustoconical transition between the second part 1113 and the distal part 112. The distal part 112 comprises elastically deformable tabs 1121 which differ from the tabs in the example of Figures 2-3 by the shape of their inner face FA.Indeed, the internal faces 22 of the tabs 1121 are no longer curved but flat and these internal faces 22 delimit between themselves an imprint E of polygonal section.

[0076] In this example, as in the examples of Figures 2 and 3, the transmission of the driving torque to the probe S results from the engagement of the ring C of tabs 1121 with the probe head S1. However, while the engagement in Figures 2 and 3 resembles a friction coupling, the engagement in Figure 4 resembles a press-fit (or geometric coupling) coupling, even though friction phenomena also come into play. Indeed, the tabs 1121 define between themselves a recess E that fits the profile of the head S1. This recess E corresponds to the portion of the central cavity 20 into which the head S1 is inserted. Thus, as illustrated in Figure 4, the tabs 1121 define a hexagonal recess that fits into the hexagonal profile of the probe head S1 shown in Figure 2. More generally, for a faceted S1 head with "N" facets, the number of tabs can be between 2 (forked configuration) and N.

[0077] This tool 10 is used as follows. After placing the body 11 on the head S1 of the probe S, the practitioner rotates the body 11 while holding it by the drive interface 1110. The body 11 then drives the probe S due to the geometric coupling between the impression E and the profile of the head S1. The tabs 1121 are then subjected to a radial force directed outwards (away from the axis A). This radial force is exerted by the larger diameter parts of the head S1, namely the edges 62, on the inner faces 22 of the tabs 1121. The more the driving torque applied to the body 11 increases, the more the radial force increases and the more the tabs 1121 move away from the axis A. This increase takes place until the driving torque reaches a threshold value, or release value, for which the tabs 1121 are so far away from the axis A that they no longer catch the head S1.There is then a "disengagement" and the driving torque transmitted to the probe does not exceed the release value. The limitation of the driving torque therefore relies on the deformation in the separation of the tabs 1121. This deformation is made possible by the mechanical properties of the material used to manufacture the body 11 and its tabs 1121, and by the geometry of the tabs 1121 and the cavity E they define.

[0078] The practitioner typically continues to rotate the tool 10 relative to the head S1 until the deformed tabs 1121 return to their original shape upon contact with the faces 60 of the probe head S, pulled back towards the axis A by their elasticity. This creates a haptic sensation of "no tightening," which may be accompanied by a "click" sound emitted by the tabs 1121 returning to contact with the faces 60. This haptic sensation and the click alert the practitioner that the target tightening torque has been reached. The practitioner then understands that it is no longer necessary to rotate the tool 10. However, if the practitioner continues to rotate the tool 10, they will feel further tightening steps and hear further clicks, each tightening step corresponding, in this example, to a 60-degree rotation of the tool 10 relative to the probe head S1.

[0079] A tightening step or "click," as mentioned above, is the effect of the rapid elastic tightening of the tabs 1121 on the faces 60 of the probe head when the rotation of the tool 10 relative to the probe S is continued (actually resumed) after the release value has been reached for the first time. The step or click thus corresponds to the resumption of rotation. This resumption of rotation occurs in "steps" when the probe head (hexagonal in the examples in the figures) has a polygonal cross-section with flat faces 60 separated by edges 62. The flat faces 60 represent regions of smaller diameter on the probe head S and allow the tightening of the tabs 1121.

[0080] It should be noted that in the example of figures 2 and 3, a haptic sensation of "no tightening" is also obtained if, during rotation, the edges 62 of the probe head S1 can engage in the grooves 1122 which separate the tabs 1121. This depends on the shape of the edges 62 (i.e. sharp or chamfered edges) and the width of the grooves 1122.

[0081] The dimensions of the cavity E, which is delimited on its sides by the tabs 1121 and at its bottom by the lug 12, are controlled. The engagement depth P1 of the head S1 between the tabs 1121 (i.e., the height along the longitudinal axis A of the contact area between the tabs 1121 and the faces 60 of the head S1) is also controlled by the lug 12. This ensures reproducible positioning of the probe head S1 in the tool 10, and the reproducibility of the forces exerted by the tool 10 on the probe.

[0082] The embodiment example in Figure 4 also differs from the example in Figures 2 and 3 in that the body 11 does not have a narrowing between its distal part 112 and its proximal part 111 and in that the body 11 and the lug 12 form a single piece made of material.

[0083] Furthermore, the tabs 1121 have a rib 26 on their inner face 22, designed to engage in a groove (not shown) on the probe head S1 when the head is positioned in the cavity E. This prevents the probe body 11 and head S1 from separating when they are pre-assembled before screwing. This rib 26 also allows the practitioner to ensure that the body 11 is properly seated onto the head S1 because, as explained previously, if the body 11 is not fully seated, this alters the torque. The rib 26 at the end of the tabs 1121 provides a tactile sensation and / or emits a "click" sound when it engages in the corresponding groove on the head S1 as the tool 10 is driven onto the probe S.

[0084] Alternatively, a magnet system or other retaining system could be provided to prevent disassembly and allow the practitioner to ensure that they have properly inserted tool 10 onto probe S.

[0085] Tests were carried out to evaluate the reproducibility of the tightening torque obtained (which corresponds to the release value). They were carried out with a probe S having a hexagonal head and the following dimensions: distance between two opposite faces 60 = 6.20 mm; distance between two opposite edges 62 = 6.70 mm; height of faces 60 (along the longitudinal axis A) = 3.00 mm; and width of faces 60 (perpendicular to the longitudinal axis A) = 2.54 mm.

[0086] For these tests, as illustrated in Figures 5A and 5B, the distal end of the probe S was fixedly mounted in a torque meter M to measure the torque applied to the probe S. The torque meter was mounted on a fixed frame (not visible in the figures). The tests consisted of two measurement campaigns. The first measurement campaign was carried out by applying a driving torque to the probe S using a torque wrench D commonly used in dental clinics, namely a hexagonal head torque wrench of the "Torque ratchet, Josef Ganter, torque range 10-70 N. cm, no. 1000701" type (see Figure 5A).Measurements of the release value (i.e. the threshold value of the drive torque applied by the wrench D to the probe S, at which the wrench D no longer drives the probe S in rotation, when the drive torque is progressively increased) were carried out for four series of twenty successive tightenings, by an operator normally handling the wrench D. The results of these series of measurements had a standard deviation of 0.64 N.cm.

[0087] A second measurement campaign was carried out by applying a driving torque to the probe S using a tool 10 as shown in Figures 2 and 3, made of PPSU (see Figure 5B). The crown C of this tool 10 was therefore made up of six deformable tabs 1121 having the dimensions shown in Figure 3E. It should be noted that the following dimensional ranges were identified in the development of the invention as advantageous for screwing an ultrasonic probe S into a dental implant I in a controlled manner, i.e., with a tightening torque between 3 and 9 N·cm, using a tool 10 having the geometry of Figure 3E, the tool 10 being made of PPSU: engagement depth P1: between 1 mm and 4.9 mm; thickness e of the tabs in the radial direction: between 0.3 mm and 3 mm; diameter difference Dif (= D2 - D1) between the diameter D2 of the head S1 and the diameter D1 of the footprint E: between 0.1 and 2 mm.

[0088] In this second measurement campaign, measurements of the release value (the value of the driving torque applied by tool 10 to probe S, at which the tool 10 no longer drives probe S in rotation, when this driving torque is progressively increased) were performed for ten series of twenty successive tightenings, by an operator using tool 10. Each series was performed with a new tool 10, all tools 10 having the same dimensions and having been manufactured in the same way. The results of these measurement series showed a standard deviation of 0.37 N·cm.

[0089] A clear decrease in the standard deviation (and therefore in the variability) of the release value is observed when using a tool 10 according to the invention, compared to measurements taken using a torque wrench. This illustrates the improved reproducibility offered by the invention. In the case of an ultrasonic probe screwed into a dental implant itself fixed in bone, such an improvement translates into an increase in the reliability of the measurement of implant stability in the bone (the tightening torque influencing the acoustic response of the implant). Figure 6 shows another embodiment of the tool 10, which differs from the previous examples in that the tool 10 also includes a screw tip 50. This screw tip 50 is used as an intermediate piece between the body 11 and the dental prosthetic element to be screwed in. The body 11 is identical to the body in the example shown in Figures 2 and 3 and will not be described again.Body 11 could also be similar to the body in the example in Figure 4.

[0090] The screw bit 50 has a connecting end 51 adapted to be engaged with the distal part 112 of the body 11 and a profiled end 53. In the example, the connecting end 51 has a polygonal cross-section, in this case hexagonal.

[0091] The profiled end 53 of the screw bit 50 is adapted for engagement with a dental prosthetic element. In the example, the profiled end 53 has a hexagonal profile 55 adapted to cooperate with a hexagonal impression 83 formed, for example, in the head 81 of a screw 80. Other complementary profile and impression shapes can, however, be considered. The screw 80 can be, for example, a prosthetic screw passing through an implant abutment to be screwed into a dental implant with a target tightening torque typically between 10 and 35 N·cm.

[0092] To screw the screw 80 (or any other dental prosthesis) with the tool 10, the procedure is, for example, as follows. The practitioner assembles the body 11 and the screw tip 50. The practitioner takes the assembled tool 10 and engages the profiled end 53 in the screw head 81. The practitioner then rotates the body 11 while holding it by the rotational drive interface 1110. The rotational drive torque applied to the body 11 by the practitioner is transmitted to the tip 50 via this rotational linkage, and then transmitted by the tip 50 to the screw 80. At the beginning of the screwing process, the applied drive torque remains moderate, as the screw 80 offers little resistance. Towards the end of the screwing process, the applied drive torque increases, as the screw 80 offers more and more resistance.The applied driving torque increases until it reaches the release value, which corresponds to the target tightening torque. When the release value is reached, the rotational link between the body 11 and the tip 50 is released: the body 11 no longer drives the tip 50 in rotation (the mechanism is "disengaged"). With the target tightening torque reached, the practitioner can disengage the profiled end 53 from the screw 80. The tool 10 is therefore as easy to handle as a conventional manual screwdriver for prosthetic screws.

Claims

DEMANDS 1. A tool for screwing a dental prosthetic element, the tool comprising a body (11) having a proximal portion (111) and a distal portion (112) integral with the proximal portion (111), wherein the proximal portion (111) of the body comprises a rotational drive interface (1110) for applying a driving torque to the body (11) about a longitudinal axis (A) of the body, wherein the distal portion (112) of the body (11) comprises: a central cavity (20) centered on the longitudinal axis (A) and adapted to receive an end of a dental prosthetic element, and a deformable portion (1120) surrounding the central cavity (20) and adapted to engage with the end of the prosthetic element introduced into the central cavity (20) and to ensure a rotational connection about the longitudinal axis (A) between the body (11) and the prosthetic element, in such a way to transmit the driving torque to the prosthetic element,in which the deformable part (1120) is capable of elastically deforming so as to release the rotational connection when the driving torque transmitted to the prosthetic element by the distal part (112) of the body exceeds a release value.

2. Tool for screwing a dental prosthetic element, the tool comprising: a body (11) having a proximal part (111) and a distal part (112) integral with the proximal part (111), and a screw tip (50) having a connecting end (51) adapted to be engaged with the distal part (112) of the body and a profiled end (53) adapted to be engaged with a dental prosthetic element, wherein the proximal part (111) of the body (11) includes a rotational drive interface (1110) to allow a driving torque to be applied to the body (11) about a longitudinal axis (A) of the body, wherein the distal part (112) of the body (11) includes: a central cavity (20) centered on the longitudinal axis (A) and adapted to receive the connecting end (51) of the screw tip (50),and a deformable part (1120) surrounding the central cavity (20) and configured to engage with the connecting end (51) inserted into the central cavity (20) and to provide a rotational connection about the longitudinal axis (A) between the body (11) and the screwdriver bit (50) so as to transmit the driving torque to the bit, screwing (50), in which the deformable part (1120) is capable of deforming elastically so as to release the rotational connection when the drive torque transmitted by the distal part (112) to the screwing tip (50) exceeds a release value.

3. Tool according to claim 1 or 2, wherein the rotational drive interface is a gripping interface, in particular a wheel, enabling a practitioner to grasp the body (11) by hand in order to apply the drive torque to it.

4. Tool according to any one of claims 1 to 3, wherein the deformable part (1120) comprises one or more elastically deformable tabs (1121), each tab (1121) having an inner face (22) which is adjacent to the central cavity (20) and which extends parallel to the longitudinal axis (A) of the body when the tab (1121) is at rest.

5. Tool according to any one of claims 1 to 4, wherein the deformable part (1120) comprises several elastically deformable tabs (1121) distributed around the longitudinal axis (A) of the body to form a ring (C) of tabs around the central cavity (20), each tab (1121) being separated from each of its adjacent tabs by a groove (1122), the proximal part of each tab (1121) being connected to the rest of the body (11) and the distal part of each tab (1121) being free.

6. Tool according to claim 4 or 5, in which the internal faces of the tabs (1121) delimit an imprint (E) of polygonal section.

7. Tool according to any one of claims 1 to 6, comprising a lug (12) projecting in the central cavity (20) in a direction parallel to the longitudinal axis (A), the lug (12) forming a stop in this direction for the prosthetic element or the screw tip (50) introduced into the central cavity (20).

8. Tool according to any one of claims 1 to 7, wherein the body (11) of the tool is made of plastic material, in particular polyphenylsulfone (PPS11), polytetrafluoroethylene (PTFE) or polyetheretherketone (PEEK).

9. Assembly comprising a tool (10) according to any one of claims 1 to 8, and a dental prosthetic element, comprising a first end adapted to be engaged with the deformable part (1120) of the body (11) or with the profiled end (53) of the screw tip (50), and a second end adapted to be screwed into a dental implant (I) or an implant abutment.

10. Assembly according to claim 9, wherein the first end has a polygonal section.

11. Assembly according to claim 10 comprising a tool (10) according to claim 5, in which the first end is adapted to be engaged with the deformable part (1120) of the body (11) having edges (62), and in which the edges (62) and the grooves (1122) of the deformable part (1120) are such that the edges (62) can engage in the grooves (1122) when the body (11) is rotated relative to the first end.

12. Assembly according to any one of claims 9 to 11, wherein the dental prosthetic element is a probe (S), in particular an ultrasonic probe.

13. Assembly according to claim 9 or 10, wherein the dental prosthetic element is a screw (80), and wherein the first end (81) of the screw (80) is adapted to be engaged with the profiled end (53) of the screw bit (50).

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