Device for monitoring the stability of a dental implant

Abstract

The invention relates to a device for monitoring the stability of a dental implant, the device comprising an ultrasound probe (100), suitable for being mechanically coupled to the implant, and a handpiece (10) connectable to the probe (100). The handpiece (10) comprises a connector (30) with a cavity suitable for receiving a connection head (110) of the probe (100). The cavity has rotational symmetry. The connector (30) comprises, on its bottom wall, a central pin, an eccentric pin and at least one magnet. The connection head (110) comprises a central connection surface and an annular connection surface such that, when the probe (100) is fitted coaxially into the connector (30), the electrical connection is established by a contact between the pins and the connection surfaces, the magnet attracting the connection head (110) towards the bottom of the cavity in order to maintain the contact.

Description

Device for monitoring the stability of a dental implant

[0001] This presentation concerns a device for monitoring the stability of a dental implant. Background

[0002] A dental implant typically takes the form of an artificial tooth root, usually made of titanium alloy, placed inside the bone of the upper or lower jaw. A dental prosthesis component is then screwed into the implant. Often, after the dental implant is placed, a healing period is necessary for bone cells to colonize the buried surface of the implant and for it to become "osseointegrated," that is, integrated into the bone without the interposition of fibrous tissue at the bone-implant interface, or border, between the bone and the implant.

[0003] Since the dental implant acts as an intermediary between the prosthetic element and the jawbone, transmitting forces to the supporting bone, it must be well integrated. The term "stability" of the implant refers to its integration within the bone. The better the integration, the greater the implant's stability.

[0004] During the aforementioned healing period, the implant is left to rest to allow it to integrate with the bone, so that it can then support the loads that will be exerted upon it. After the healing period, the practitioner places the prosthetic component into the dental implant. Monitoring the implant's stability in the bone, that is, verifying proper osseointegration, is therefore essential for the success of the treatment, particularly for determining precisely when to end the healing period and load the implant with the prosthetic component.

[0005] Patent documents EP 2503954 and EP3781040 describe devices for controlling the stability of a dental implant.

[0006] The operating principle of these devices involves screwing an ultrasonic probe into the dental implant after it has been anchored in the bone. An electrical pulse is then sent to the probe, causing an ultrasonic wave to propagate through the implant. The probe, which operates in transmit / receive mode, collects the reflected ultrasonic wave and emits an electrical measurement signal representing the reflected ultrasonic wave. A signal processing unit, located away from the probe, assesses the implant's stability based on the measurement signal received from the probe via an electrical connection.

[0007] To acquire the measurement signal, it is essential to maintain the electrical connection between the processing unit and the probe for a certain period, estimated to be between 50 milliseconds and one second. Therefore, a stable electrical connection is necessary.

[0008] However, a permanent wired electrical connection between the treatment unit and the probe does not satisfy practitioners due, in particular, to its lack of ergonomics and the fact that it complicates the installation of the probe on the implant.

[0009] Therefore, there is a need for a solution that allows for a temporary but stable electrical connection between the treatment unit and the probe. Such a connection must be easily established regardless of the probe's position inside the patient's mouth. General presentation

[0010] This presentation concerns a device for monitoring the stability of a dental implant inserted into bone. The dental implant has one free end protruding at the bone surface and one end embedded in the bone. The device comprises a handpiece, i.e., an instrument designed to be held in the hand, and an ultrasonic probe. The probe and handpiece are designed to cooperate and, in particular, to be electrically connected.

[0011] The ultrasonic probe is designed to be mechanically coupled to the implant, for example by screwing the probe into the implant. The probe includes an ultrasonic transducer adapted to emit an ultrasonic wave propagating inside the implant towards the buried end, to collect the reflected ultrasonic wave, and to emit an electrical measurement signal representing the reflected ultrasonic wave.

[0012] The dental handpiece includes an electronic circuit designed to be connected to the ultrasonic transducer via an electrical connection. The electronic circuit includes a processing unit configured to assess the stability of the dental implant based on the measurement signal received from the ultrasonic transducer through the electrical connection.

[0013] The ultrasonic probe includes a connecting head. The dental handpiece includes a shaft and a connector located at one end of the shaft. The connecting head works with the connector to establish the electrical connection between the probe and the handpiece.

[0014] The connector has a cavity designed to receive the connection head. The cavity has rotational symmetry about a principal axis and is bounded by a bottom wall and a side wall. The connector includes, on its bottom wall, a central pin, an eccentric pin, and at least one magnet. The pins establish the electrical connection.

[0015] The connector head has a central axis, a central connection surface centered on the central axis, and an annular connection surface around the central axis. When the connector head is coaxially engaged in the connector cavity, the electrical connection is ensured by contact between the central pin and the central connection surface, and by contact between the eccentric pin and the annular connection surface. The magnet(s) attract the connector head toward the base wall to maintain contact between the central pin and the central connection surface, and between the eccentric pin and the annular connection surface. In other words, the connector's magnet(s) magnetically attract the connector head to hold it pressed into the cavity, thus ensuring stable contact between the pins and the connection surfaces.

[0016] The cavity's rotational symmetry and the arrangement of the pins and connection surfaces allow for easy electrical connection regardless of the handpiece shaft's orientation relative to the ultrasound probe's central axis. In other words, the practitioner does not need to position the shaft at a specific angle to make the connection. Furthermore, once the connector is brought over the connection head, the magnetic attraction exerted by the magnet can facilitate contact between the pins and connection surfaces. Finally, this magnetic attraction ensures a stable electrical connection for the duration of the measurement signal acquisition by the processing unit.

[0017] The aforementioned features and advantages, as well as others, will become apparent upon reading the detailed description that follows of embodiments of the proposed device. This detailed description refers to the attached drawings, which depict an example of the device.

[0018] The accompanying drawings are schematic and not necessarily to scale; their primary purpose is to illustrate the principles of the invention. In these drawings, from one figure (fig.) to another, identical elements (or parts of elements) are identified by the same reference numerals. This figure represents an example of a device according to the invention. This device comprises an ultrasonic probe and a handpiece. The handpiece comprises a housing and a shaft. One end of the shaft is connected to the housing. The shaft has a connector at its other end that can be connected to the ultrasonic probe. This figure is a top view of the connector and the probe. This figure is a bottom view of the connector. This figure is a longitudinal sectional view of the connector. Detailed description

[0019] Embodiments of the proposed device are described in detail below. Some embodiments are described with reference to the example shown in the accompanying drawings. These embodiments illustrate the features and advantages of the invention. However, it should be noted that the invention is not limited to the embodiments described or to the example shown.

[0020] In general and with reference to the example in the figures, the proposed device includes an ultrasonic probe 100 and a handpiece 10. The handpiece 10 is adapted to be held in the hand by a practitioner, in particular a dentist, or any other user wishing to check the stability of a dental implant previously inserted into a patient's jawbone.

[0021] The dental implant is not shown in the figures. Typically, such an implant has a tapered shape and an external thread so that it can be screwed into the bone. For example, the implant has an outer diameter of 3 to 6 mm and a length of 4 to 16 mm. Once anchored in the bone, the implant has a free end emerging at the bone surface, as opposed to an end embedded in the bone, so that the free end is accessible in vivo. The free end of the implant is used as the receiving site for the 100 probe. In other words, the 100 probe can be mechanically coupled to the implant at this free end. For example, the free end of the implant is hollow and has an internal thread, while the distal end 102 of the probe 100 is elongated and has an external thread 104 so that it can be screwed into the internal thread of the implant.

[0022] The probe 100 includes a piezoelectric ultrasonic transducer capable of emitting an ultrasonic wave. When the probe 100 is coupled to the implant, the emitted ultrasonic wave propagates inside the implant to the end embedded in the bone. The ultrasonic transducer is capable of collecting the reflected ultrasonic wave and emitting an electrical measurement signal representing the reflected ultrasonic wave. In other words, the ultrasonic transducer emits the ultrasonic wave, receives the echoes resulting from the reflection of the ultrasonic wave at a contact interface between the implant and the bone, and transmits the measurement signal to the handpiece 10.

[0023] The handpiece 10 includes a housing 12 containing an electronic circuit (not shown) that can be connected to the ultrasonic transducer via an electrical connection. In some embodiments, the electronic circuit includes a control circuit for controlling the ultrasonic transducer, i.e., for sending an electrical pulse to the transducer to induce the emission of an ultrasonic wave. The electronic circuit also includes a processing unit configured to receive the measurement signal from the transducer and process this signal to assess the stability of the dental implant. Various methods for processing the measurement signal are known (see, in particular, patent documents EP2503954 and EP3781040) and will not be described in further detail here.The housing 12 may include control buttons 16 to control the electronic circuit and a display device 14 to display, in particular, an indicator (calculated by the processing unit) reflecting the stability of the dental implant and thus informing the practitioner.

[0024] The handpiece 10 also includes a shaft 20 having two opposing ends 21, 22. The proximal end 21 of the shaft is connected to the housing 10. In some embodiments, such as in the example in the figure, the shaft 20 is detachably connected to the housing 12. This allows for independent sterilization of the shaft 20 and / or easy replacement. The shaft 20 is shown in the detached position in the figure. Various fastening systems for connecting the shaft 20 to the housing 10 can be considered. The elongated shape of the shaft, inspired by contra-angles commonly used in dental handpieces, allows access to all (or at least most) locations where dental implants can be placed. For this same purpose, a fastening system allowing rotation of the shaft 20 around an engagement axis X of the shaft 20 in the housing 12 can be considered.

[0025] At its distal end 22, the shaft 20 includes a connector 30. At its proximal end, the ultrasonic probe 100 includes a connecting head 110. The connecting head 110 cooperates with the connector 30 to establish an electrical connection between the probe 100 and the handpiece 10. In some embodiments, the connecting head 110 has an end face 115 and a lateral face 116. The lateral face 116 may have several facets. In the example shown, the connecting head 110 is hexagonal and therefore has six lateral facets. These lateral facets allow the probe 100 to be screwed into the implant by means of a suitable tool that engages with the facets. The lateral face 116 fits within a cylinder of revolution of diameter D1 shown in dashed lines on the figure.The connecting head has a central axis A (see) and, on its end face 115, a central connecting surface 112 centered on the axis A and an annular connecting surface 114 around the axis A. In other words, the annular connecting surface 114 encircles the central connecting surface 112. The annular connecting surface 114 can be formed by a ferromagnetic ring embedded in the end face 115. The annular and central connecting surfaces 114, 112, are at the same level so that the end face 115 is flat.

[0026] The connector 30 has a cavity 40 adapted to receive the connection head 110. The cavity 40 has rotational symmetry about a principal axis B and is delimited by a bottom wall 41 and a side wall 42. The connector 30 includes, on its bottom wall 41, a central pin 31, an eccentric pin 32, and at least one magnet 33. In the example shown in the figures, the bottom wall 41 is flat and perpendicular to the principal axis B. The pins 31 and 32 protrude from the bottom wall 41, while each magnet 33 is embedded in this wall 41, such that the free face of each magnet 33 is recessed relative to the free end of the pins 31 and 32. The pins 31 and 32 are of the same height.

[0027] When the connecting head 110 is coaxially engaged (i.e., with axes A and B aligned) in the cavity 40 of the connector 30, the electrical connection is ensured by contact between the central pin 31 and the central connection surface 112, and by contact between the eccentric pin 32 and the annular connection surface 114. The magnet(s) 33 attract the connecting head towards the base wall 41 to maintain the connection surfaces 112, 114 in contact with the pins 31, 32. The electrical connection can be broken by detaching the connector 30 from the connecting head 110. To do this, the practitioner manually applies a pulling force to the handpiece 10 that exceeds the magnetic attraction force. The intensity of the magnetic attraction force exerted by the magnet(s) 33 is determined by finding a compromise.The attractive force must be high enough to maintain a stable electrical connection between the connecting surfaces 112, 114 and the pins 31, 32, but low enough to limit the mechanical stresses exerted on the probe 100 (and therefore on the implant) when the connector 30 is detached, as these stresses could compromise the implant's stability. In some embodiments, the magnitude of the attractive force exerted by the magnet(s) 33 is between 0.2 and 2 Newtons (N), in particular between 0.5 and 1 N. This attractive force, or magnetizing force, corresponds to the normal force required to separate the connecting head 110 from the connector 30 (i.e., to separate the ferromagnetic part of the connecting head 110 from the magnet(s) 33 of the connector 30). This force can be measured, for example, using a dynamometer.

[0028] The magnet(s) 33 can be arranged around the central pin 31 so as to face the ferromagnetic ring when the connecting head 110 is engaged coaxially in the cavity 40. In some embodiments, the connecting head 110 comprises at least two magnets 33 distributed around the central pin 31.

[0029] The magnet(s) 33 can be arranged symmetrically around the central pin 31 so that the magnetic attraction force exerted by the magnet(s) 33 is parallel, or substantially parallel, to the principal axis B of the cavity 40. This keeps the connecting head 110 aligned with the cavity 40. In particular, when the connecting head 110 rests against the central pin 31, this prevents the connecting head 110 from pivoting around the central pin 31 under the effect of the attractive force. Thus, in embodiments with one magnet, the magnet can have an annular shape centered on the central pin 31. In embodiments with two magnets, the magnets can be diametrically opposed with respect to the central pin 31. In embodiments with three or more magnets, the magnets can be evenly distributed around the central pin 31.For example, three magnets 33 can be angularly distributed every 120° around the central pin 31. In the example in the figures, the connecting head 110 comprises three magnets 33. The three magnets 33 and the eccentric pin 32 are angularly distributed every 90° around the central pin 31. Although such an arrangement of the magnets 33 is not symmetrical around the central pin 31, it gives satisfactory results.

[0030] In some embodiments, the central pin 31 and the eccentric pin 32 are spring-loaded pins. Specifically, each pin 31, 32 consists of a plunger, a barrel, and a spring. When a force is applied to the plunger, the spring is compressed, and the plunger moves inside the barrel. The shape of the barrel retains the plunger, preventing the spring from pushing it outward. This type of pin provides an electrical connection resistant to small relative movements between the connector 30 and the connection head 110, thus enhancing the stability of the electrical connection. Furthermore, the combined attractive force of the magnets 33 and the spring-loaded pins 31, 32 proves particularly effective.

[0031] The geometry of the cavity 40, the connecting head 30, and their connectors (i.e., the pins and connection surfaces) allows for an electrical connection regardless of the orientation of the rod 20 around the central axis A of the probe 100. Furthermore, the action of the magnets 33 helps maintain this electrical connection for the time required for the processing unit to acquire the measurement signal. Finally, the shape of the rod 20 and the compact connectors overcome the space constraints encountered in the device's environment of use, namely the patient's mouth.

[0032] In some embodiments, the connecting head 110 fits within a cylinder of revolution with diameter D1, and the cylindrical lateral wall 42 of the cavity 40 has a diameter D2. The clearance between D1 and D2 is denoted E, where E = D2 - D1. This clearance E is determined by finding a compromise. The clearance E is small enough to ensure proper centering of the connecting head 110 within the connector 30, and therefore correct relative positioning of the pins 31, 32, and the connection surfaces 112, 114, but large enough to avoid exerting mechanical stress on the probe 100 (and thus on the implant) during the positioning of the connector 30 onto the probe 100 or during its detachment, as this could compromise the stability of the implant.

[0033] In some embodiments, the height P (illustrated in the figure) of the cylindrical side wall 42 of the cavity 40 also results from the search for a compromise. The height P is large enough to ensure good guidance of the connecting head 110 in the connector 30, but small enough not to exert torque on the probe 100 (and therefore on the implant) when the connector 30 is connected to the probe 100, as this could compromise the stability of the implant.

[0034] In some embodiments, to facilitate handling and placement of the probe 100 and due to anatomical constraints, the diameter D1 of the connecting head 110 is between 3 and 12 mm, particularly between 6 and 7.5 mm. For example, the diameter D1 measures 6.7 mm. In this case, the clearance E can be between 0.01 and 0.8 mm, particularly between 0.05 and 0.6 mm, and preferably between 0.1 and 0.4 mm. A clearance E of 0.2 mm gives good results. The height P of the cylindrical lateral wall of the cavity can be between 1.5 and 4.5 mm, particularly between 2.5 and 3.5 mm. A height P of 3.1 mm gives good results.

[0035] The embodiments described in this presentation and the example shown in the figures are given for illustrative purposes only and are not limiting; a person skilled in the art could easily, in view of this presentation, modify these embodiments, or consider others, while remaining within the scope of the invention.

[0036] In particular, a person skilled in the art will readily be able to envision variations comprising only some of the features of the embodiments described above, if those features alone are sufficient to provide one of the advantages of the invention. Furthermore, the various features of these embodiments can be used individually or combined. When combined, these features can be used as described above or otherwise; the invention is not limited to the specific combinations described herein. In particular, unless otherwise specified, a feature described in relation to one embodiment can be applied analogously to another embodiment.

Claims

A device for monitoring the stability of a dental implant inserted into bone, the dental implant having a free end emerging on the surface of the bone and an end buried in the bone, the device comprising: an ultrasonic probe (100) adapted to be mechanically coupled to the implant and comprising an ultrasonic transducer adapted to emit an ultrasonic wave propagating inside the implant towards the buried end, to collect the reflected ultrasonic wave and to emit an electrical measurement signal representing the reflected ultrasonic wave, and a handpiece (10) adapted to cooperate with the probe (100), the handpiece (10) comprising an electronic circuit connectable to the ultrasonic transducer via an electrical connection, the electronic circuit comprising a processing unit configured to evaluate the stability of the dental implant based on the measurement signal received from the ultrasonic transducer (100) via the electrical connection.wherein: the probe (100) comprises a connecting head (110); the handpiece (10) comprises a rod (20) and a connector (30) located at one end of the rod (20); the connector (30) has a cavity (40) adapted to receive the connecting head (110), the cavity (40) having rotational symmetry about a principal axis (B) and being delimited by a bottom wall (41) and a cylindrical side wall (42), the connector (30) comprising, on the bottom wall (41), a central pin (31), an eccentric pin (32) and at least one magnet (33); the connecting head has a central axis (A), a central connecting surface (112) centered on the central axis (A) and an annular connecting surface (115) about the central axis (A), such that, when the connecting head (110) is coaxially engaged in the cavity (40),The electrical connection is ensured by contact between the central pin (31) and the central connection surface (112) and by contact between the eccentric pin (32) and the annular connection surface (115), said magnet (33) attracting the connection head (110) towards the bottom wall (41) to maintain said contacts. Device according to claim 1, wherein the connection head (110) fits into a cylinder of revolution of diameter D1 between 3 and 12 mm. Device according to claim 2, and in which the diameter D2 of the cylindrical side wall (42) of the cavity (40) is such that the clearance E between the diameters D1 and D2 is between 0.01 and 0.8 mm, in particular between 0.1 and 0.4 mm. Device according to any one of claims 1 to 3, wherein the height P of the cylindrical side wall (42) of the cavity (40) is between 1.5 and 4.5 mm, in particular between 2.5 and 3.5 mm. Device according to any one of claims 1 to 4, wherein the connecting head (110) comprises a ferromagnetic ring disposed around the central axis (A) and wherein said at least one magnet (33) is disposed around the central pin (31) so as to face the ferromagnetic ring when the connecting head (110) is engaged coaxially in the cavity (40). Device according to claim 5 in which the annular connection surface (115) corresponds to a face of the ferromagnetic ring. Device according to any one of claims 1 to 6, wherein the connection head (110) comprises at least two magnets (33) distributed around the central pin (31). Device according to any one of claims 1 to 7, wherein the intensity of the magnetic attraction force exerted by said at least one magnet is between 0.2 and 2 N, in particular between 0.5 and 1 N. Device according to any one of claims 1 to 8, wherein the central pin (31) and the eccentric pin (32) are spring-loaded pins.

Images