Instrumented endodontic file for determining anatomical data

Abstract

INSTRUMENTED ENDODONTIC FILE FOR DETERMINING ANATOMICAL DATA The present invention relates to a device for endodontic treatment of a root canal (11), comprising: - an instrumented file (20) including a passive zone (22) and an active zone (21), the active zone (21) being configured to provide position data by electromagnetic or optical radiation, - acquisition means (30) including a sensor (31), and configured to acquire position data within a system defined by the root canal (11) and the acquisition means (30), and - a treatment unit (40) connected to the acquisition means (30), and the treatment unit (40) is configured to process the position data of the active zone (21) within the system, in order to determine an anatomical datum of the root canal (11). Abstract figure: Fig. 4

Description

Title of the invention: Instrumented endodontic file for determining an anatomical feature. Scope of the invention

[0001] The present invention relates to the technical field of endodontics. STATE OF THE ART

[0002] In the field of endodontics, a frequent complication is instrument breakage within a root canal during treatment.

[0003] This may be an elasto-plastic rupture due to a defect in the material in which the instrument is made, a fatigue rupture due to use of the instrument beyond its intended service life, or a ductile rupture due to over-stressing of the instrument.

[0004] This over-stressing is particularly likely to occur when the root canal has a bent geometry, or a sudden narrowing of section: at the level of these "risk zones", the instrument is put under stress.

[0005] If the practitioner has not previously identified the risk areas of the canal to be treated, he may approach these areas without taking the necessary precautions, such as reducing the rotation speed of the instrument, or manually applying less force.

[0006] It is observed that the majority of instrument breakages result from a canal geometry poorly understood by the practitioner, who consequently did not take adequate precautions when treating a risk area.

[0007] Various solutions exist, but do not give complete satisfaction.

[0008] One solution involves handpieces equipped with force sensors. If excessive stress is applied to the file, the sensor detects it and automatically adjusts the instrument's dynamics, or issues an alert to the practitioner. However, significant stress is already applied to the file, so breakage prevention is not optimal.

[0009] A second solution lies in apex locators, which are devices that use the measurement of an electrical signal applied between an endodontic instrument and the patient's body, such as a lip. When the instrument reaches the apex of the canal, the electrical signal changes radically, so monitoring the electrical signal makes it possible to detect whether the instrument has reached the apex of the canal.

[0010] An apex locator is used: - either upstream of the treatment, in order to measure the distance separating an occlusal face of the tooth and the apex, known as the "working length"; - either during treatment, in order to assess the working depth, i.e. the position of the instrument tip within the canal.

[0011] Knowing the working depth allows the practitioner to adapt his technique as the file descends into the root canal.

[0012] However, use during treatment is hampered by the presence of tissue within the canal, or by the presence of fluids such as pus or irrigation solutions like sodium hypochlorite. Indeed, tissues and fluids alter the conduction of the electrical signal, compared to use within a dry root canal. The detection of changes in the electrical signal value is less effective.

[0013] It follows that monitoring the electrical signal provides reliable information when the instrument is located at the apex, but not when the instrument is located below the apex. An apex locator used during treatment is therefore inaccurate.

[0014] A third solution lies in imaging methods such as radiography.

[0015] A diagnostic radiograph, as illustrated in [Fig.1], is a two-dimensional radiograph of the tooth (10) to be treated, allowing visualization of the general trajectory (D) of the root including the root canal (11) to be treated.

[0016] Diagnostic radiography is primarily intended to illustrate the presence of inflammation or necrosis requiring endodontic treatment. Since it consists of only a single two-dimensional image, diagnostic radiography cannot detect: - a curvature of the root canal (11), and which would be in a plane parallel to an axis of radiography; - the section (S) of the root canal (11), which is not necessarily circular.

[0017] Two-dimensional radiographs can also be taken during treatment, in order to check the progress of the treatment and in particular to inspect whether the tip of the instrument is indeed at the level of the apex.

[0018] Another radiography technique is cone beam computed tomography (CBCT). This technique allows for a three-dimensional reconstruction of the canal to be treated, as well as several projections along each of these three dimensions, by means of the digital assembly of several hundred individual radiographic images.

[0019] A non-circular section of a channel is detectable by means of a CBCT, as illustrated in [Fig.2].

[0020] On the other hand, although a CBCT provides a three-dimensional reconstruction, it is only an assembly of individual radiographic images, so that the geometry of the root canal as such is not accessible: it is necessary to navigate, using a graphical interface, between the different radiographs acquired in order to try to visualize the desired anatomical data of the root canal.

[0021] Another disadvantage of radiography lies in the amount of ionizing radiation inflicted: - to the patient, and which is important in the case of a CBCT; - to the practitioner, and which is reasonable in the case of radiographs taken during treatment but which is inflicted repeatedly. SUMMARY

[0022] There is therefore a need to improve devices enabling a practitioner to obtain anatomical data of the canal upstream of treatment without using ionizing radiation.

[0023] There is also a need, during the treatment, to obtain the working depth reliably, and without using ionizing radiation.

[0024] To this end, a device has been developed for endodontic treatment of a root canal of a patient's tooth root, comprising: - an instrumented file comprising a passive zone and an active zone, the active zone being configured to provide position data by electromagnetic or optical radiation, - acquisition means comprising a sensor, and configured to acquire position data within a system defined by the root canal and the acquisition means, and - a processing unit connected to the acquisition means.

[0025] According to the invention, the processing unit is configured to process the position data of the active zone within the system, in order to determine an anatomical feature of the root canal. The anatomical feature of the root canal may be, for example, a trajectory of the root canal, or the fact that an apex of the root canal is reached by a tip of the file.

[0026] Since the position data is transmitted by electromagnetic or optical radiation: - We avoid using ionizing radiation, which is safer for both the patient and the practitioner - Position data is not impacted by the presence of fluids as the electrical signal of an apex locator can be.

[0027] The device according to the invention is therefore reliable, and can be used during treatment without being impacted by the presence, for example, of irrigation solution.

[0028] In an embodiment that allows verification during treatment of whether the file tip is located at the apex, the active zone exhibits a different magnetism than the passive zone, the sensor is a magnetic sensor, and the sensor is configured to be placed in the patient's vestibule, at the level of the root canal apex. Preferably, the magnetism of the active zone is greater than that of the passive zone, particularly when the file is made of a material with low magnetic susceptibility.

[0029] Since the general trajectory of the root is already known by means of a diagnostic radiograph, the acquisition means preferably comprise several sensors arranged along an axis configured to be substantially parallel to the general trajectory of the tooth root, from a pulp chamber of the tooth to the apex of the root canal. This makes it possible to place the sensors in the patient's vestibule without needing to precisely adjust the position of a single sensor relative to the apex of the canal. As the working length is known, it is possible to identify the sensor closest to the apex. Furthermore, it is possible to determine the working depth by identifying which sensor the tip of the file is positioned relative to.

[0030] Advantageously, the file includes several active zones, i.e. several zones with high magnetism, in order to make the position data obtained more reliable, by redundancy.

[0031] In order to simplify the implementation of the acquisition means, they include a sensor matrix, defining a plane in which the sensors are distributed according to a two-dimensional system.

[0032] The planar distribution of the sensors ensures that, regardless of the channel's trajectory, several magnetic sensors will be in front of it and will be able to detect the passage of magnetic active zones within it.

[0033] Such a sensor array provides a two-dimensional trajectory of the channel, each sensor in the array providing information about the passage of an active zone relative to it when the file is inserted into the channel. The use of magnetic sensors configured to measure the intensity of the magnetic field, such as magnetoresistance sensors, makes it possible to obtain a three-dimensional trajectory. Indeed, an increase in the signal means that the channel is moving closer to the array, while a decrease in the signal means that the channel is moving away from the array.

[0034] In order to ensure that the distance separating each of the matrix sensors and the root canal is as homogeneous as possible, the matrix is ​​arranged substantially parallel to the general trajectory of the root, and extending from a chamber from the pulp of the tooth to an apex of the canal. A uniform distance is advantageous for measuring the intensity of the magnetic field.

[0035] In a preferred embodiment, the device comprises two sensor arrays with the aforementioned characteristics, and the two arrays are configured to be arranged in two non-parallel planes. This embodiment makes it possible to obtain, by intersecting the data obtained by each of the arrays, the three-dimensional trajectory of the channel. Furthermore, this embodiment avoids the additional cost of magnetic sensors configured to measure magnetic field strength.

[0036] In the preferred embodiment, the processing unit can be programmed to: - to acquire several position data points when the file is manipulated within the root canal, at a given depth within the root canal, - from several position data of a given depth, determine a section of the root canal at that depth.

[0037] This embodiment allows the geometry of the root canal to be obtained by interpolating the geometry from several sections obtained.

[0038] In a second embodiment, an active zone comprises a first end of an optical fiber that terminates at the tip of the file, and a second end of the optical fiber connected to the sensor, which is an optical sensor. This feature allows: - to perform image recognition, for example to obtain the channel cross-section at a given depth, or - to perform a visual observation of the canal, in order to detect a bifurcation where the canal splits into two secondary canals.

[0039] In this second embodiment, the optical sensor is preferably a laser remote sensing transceiver (LIDAR, or light detection and ranging). A LIDAR acquisition makes it possible to determine the geometry of an internal surface of the canal, opposite the first end of the optical fiber. Reconstruction of the geometry is then possible, based on the continuity of the surfaces obtained when the file is introduced into the canal.

[0040] A third embodiment combines the first embodiment and the second embodiment, that is to say, it includes at least one active zone having a magnetism different from that of the passive zone, as well as an active zone comprising a first end of an optical fiber which opens at the tip of the file, and a second end of the optical fiber connected to an optical sensor of the acquisition means.

[0041] The invention also relates to an instrumented file, configured to cooperate with the device according to the aforementioned characteristics. BRIEF DESCRIPTION OF THE FIGURES

[0042] [Fig. 1] is an illustration of a two-dimensional radiograph of a tooth to be treated, illustrating the deficient nature of this technology alone.

[0043] [Fig.2] is an illustration of a graphical interface of a software program allowing to exploit cone beam computed tomography (CBCT), illustrating the limitations of this technology.

[0044] [Fig.3] is a diagram illustrating a root canal within a tooth root whose pulp chamber was opened for endodontic treatment.

[0045] [Fig.4] is a diagram illustrating a first embodiment of the invention, in in which two arrays of magnetic sensors detect the position of several magnetic active zones.

[0046] [Fig.5] is a diagram illustrating an anatomical datum obtained, in the form of trajectory of the root canal.

[0047] [Fig.6] is a diagram illustrating an anatomical datum obtained, in the form of geometry calculated from a root canal trajectory and root canal sections at different depths.

[0048] [Fig.7] is a diagram illustrating a third embodiment comprising several magnetic active zones exhibiting a different magnetism from that of the passive zone, as well as an optical active zone comprising a first end of an optical fiber. DETAILED DESCRIPTION

[0049] Figure 1 illustrates a two-dimensional radiograph, of the type used as a diagnostic radiograph. A diagnostic radiograph allows the practitioner to check for the presence of inflammation or tissue necrosis within a root canal (11) of a tooth (10), which indicates the need for endodontic treatment.

[0050] Such a radiograph also makes it possible to identify the general direction (D) of the root of the tooth (10), as well as the general direction (D) of the root canal (11) to be treated.

[0051] A working length (Lt), defined as the distance between an occlusal surface (12) of the tooth (10) and the apex (13) of the root canal (11), can be measured on a diagnostic radiograph. However, more precise systems are preferred, such as an apex locator (13) cooperating with an exploratory file.

[0052] Figure 2 illustrates a graphical interface for processing images obtained by cone beam computed tomography (CBCT). Several hundred X-rays are acquired, from different directions, so that a three-dimensional reconstruction can be offered to the practitioner.

[0053] Three dials (I, II, III) of the graphical interface illustrate two-dimensional radiographs in the three anatomical directions: frontal, sagittal, and transverse. A fourth dial (IV) illustrates a three-dimensional reconstruction.

[0054] The section (S) of the root canal (11) is observable on the third quadrant (III), which illustrates the section in a transverse plane. The practitioner must navigate between several successive transverse sections in order to correctly understand the section (S) of the root canal (11) along its entire length.

[0055] The reconstruction illustrated on the fourth quadrant (IV) has a more figurative than clinical utility, insofar as the reconstruction includes all the tissues of the radiographed jaw, and the bone, dentin and cementum hinder observation of the root canal (11).

[0056] Figure 3 illustrates a diagram of a tooth (10) whose pulp chamber (14) has been opened for endodontic treatment. The root canal (11) here presents two curves (C), which are areas of risk during treatment.

[0057] Areas of risk may include a sudden decrease in the cross-section (S) of the root canal (11), a significant curvature (C) of the root canal (11), or a bifurcation of the root canal (11) into several secondary canals.

[0058] The more information the practitioner has on the geometry (G) of the root canal (11) to be treated, the lower the risks of failure and instrument breakage.

[0059] Figure 4 illustrates a first embodiment of the invention in which an endodontic file (20) comprises several active zones (21), the magnetism of which is different from that of a passive zone (22) of the file (20). The active zones (21) are distributed uniformly along a blade of the file (20), which extends from a proximal end connected to a handle (23) of the file (20), to a distal end, referred to as the tip (24) of the file (20).

[0060] The different magnetism of an active zone (21) is understood as a magnetism greater or less than that of the passive zone (22).

[0061] In practice, the files (20) are generally made from a nickel-titanium alloy (“nitinol” or “Niti”), which has low magnetic susceptibility. In this case, the active area (21) preferably comprises a material with high magnetic susceptibility.

[0062] These may be pellets made of steel or permanent magnets, fixed to the file (20) by any suitable means such as welding, gluing, or shrink fitting.

[0063] The position of the active zones (21) is detected by means of an acquisition device (30) comprising a plurality of magnetic sensors (31), configured to detect the active zones (21), in contrast to the different magnetism of the passive zone (22).

[0064] In this embodiment, the active zones (21) provide position data by electromagnetic radiation, and more specifically by magnetism. The position data is not provided by measuring an electrical signal within the file (20).

[0065] The magnetic sensors (31) are of any suitable type, and can be of the type of magnetic field sensors with small scale microelectromechanical systems (“MEMS” according to the English Microelectromechanical Systems), or even Hall effect sensors.

[0066] The magnetic sensors (31) are arranged in a plane and according to a matrix (32), so as to define a two-dimensional system. Within this matrix (32): - when a magnetic sensor (31) is in view of an active zone (21), it detects it and switches to an active state; - when a magnetic sensor (31) is not in view of an active zone (21), that is to say that it is in view of a passive zone (22) or that it is not in view of the file (20), then the magnetic sensor (31) is in an inactive state.

[0067] To simplify [Fig. 4], only a few magnetic sensors (31) are shown. The distribution of the magnetic sensors (31) defines pixels. The matrix (32) shown is square because the distribution of the magnetic sensors (31) is regular in two orthogonal directions, but other types of distributions can be considered, such as a hexagonal distribution.

[0068] The magnetic sensors (31) in the active state define active pixels (PI), shown in black. Conversely, the sensors in the inactive state define inactive pixels (PO), shown in white.

[0069] Within a system defined by the root canal (11) and the means (30) for acquiring the position of the active zones (21), the position data in this case is the identification of the magnetic sensors (31) with respect to which a magnetic active zone (21m) is located. The anatomical data is a profile (P) defined by the active pixels (PI), corresponding to a planar projection of the trajectory (T) of the root canal (11) onto the matrix (32).

[0070] If the magnetic sensors (31) used are configured to measure the intensity of the magnetic field, then a single matrix (32) of magnetic sensors (31) is sufficient to obtain the trajectory (T) of the root canal (11) in three dimensions: - the trajectory (T) along the first two directions (x, z) are directly obtained by the active pixels (PI); - the trajectory (T) along the third direction (y) is obtained by the intensity of the signal provided by each magnetic sensor (31): - a strong signal is equivalent to a short distance between the magnetic sensor (31) and the active area (21); - a weak signal is equivalent to a high distance between the magnetic sensor (31) and the active area (21).

[0071] Although this embodiment does not directly provide the position of the root canal (11) within the root, since the third dimension is measured relatively, it may be sufficient to characterize the presence of curvatures (C) which define areas at risk.

[0072] Another technique is to measure, using a matrix (32), the distance separating two magnetic active zones (21m): - if the distance measured between two active zones (21m) within the root canal (11) is equal to the distance separating these two magnetic active zones (21m) from the file (20) at rest, then the file (20) within the root canal (11) is straight on a portion of the root canal (11) separating these two magnetic active zones (21m). - if the measured distance between two active zones (21m) within the root canal (11) is less than the distance separating two magnetic active zones (21m) of the file (20) at rest, then the file (20) within the root canal (11) is curved on the portion of the root canal (11) separating these two magnetic active zones (21m).

[0073] Although this method does not allow identification of the direction of the curvature (C) of the root canal (11), it nevertheless allows detection and quantification of this curvature (C), which is already important information for the practitioner regarding the difficulty of the procedure to be performed.

[0074] The determination of the curvature of the file (20) based on the measurement of the distance between active zones (21m) can be applied to two successive active zones (21m), or preferably be applied simultaneously to several active zones (21m), or even take into account the distances separating several successive pairs of active zones (21m), in order to define the curvature (C) by the calculation of the profile (P) comprising several points.

[0075] Magnetoresistance and the measurement of the distance separating two magnetically active zones (21m) can be used as alternatives. They are preferably used in combination, in order to improve the results obtained using a single array (32) of magnetic sensors (31). Placing a single array (32) inside the patient's mouth is less cumbersome.

[0076] It is understood that it is not necessary for one of the directions of the distribution of the magnetic sensors (31) to be parallel to the general direction (D) of the root: it is sufficient that the matrix (32) defines pixels whose distribution and resolution make it possible to determine a profile (P) of the root canal (11).

[0077] In the preferred embodiment that is illustrated, the acquisition means (30) comprise two matrices (32), arranged in a non-parallel manner with respect to each other, in order to define a three-dimensional system.

[0078] In practice, the matrices (32) are placed in the vestibule of the patient's mouth, on either side of the tooth (10) to be treated, at an angle of between 10° and 20° to each other, along an axis substantially parallel to the general direction (D) of the root of the tooth (10). The general direction (D) of the root of the tooth (10) is substantially orthogonal to the transverse plane of the patient.

[0079] In the illustrated example, the two matrices (32) are square, and are arranged such that: - a first matrix (32) defines an x-axis substantially parallel to the transverse plane and a z-axis substantially orthogonal to the transverse plane, - a second matrix (32) defines a y-axis substantially parallel to the transverse plane and forming an angle between 10° and 20° with respect to the x-axis, and the second dimension of the second matrix (32) is the z-axis.

[0080] When two matrices (32) are used to define a three-dimensional system, it is not imperative that each of the matrices (32) be parallel to the general direction (D) of the root, since it suffices that the root canal (11) be contained within a volume defined by the intersection between: - a first volume whose base is defined by the first matrix (32) and whose height is defined by the detection depth of the magnetic sensors (31), and - a second volume is defined in a similar way, by the second matrix (32).

[0081] To facilitate the positioning of the matrices (32), they are placed on a clip made of non-magnetic material. Clips are commonly used in endodontics and can be directly attached to the tooth (10) to be treated. The matrices (32) are thus located in the immediate vicinity of the root canal (11).

[0082] Arranging the matrix(s) (32) parallel to the general direction (D) of the root allows the sensors to be placed as close as possible to the tooth (10), which can allow better detection of the active areas (21) (better signal quality).

[0083] In the preferred embodiment with two matrices (32), the trajectory (T) of the root canal (11) in three dimensions is obtained by calculating the intersection, in volume, of the two profiles (P) each obtained by a matrix (32).

[0084] Within a system defined by the root canal (11) and the acquisition means (30), the position data in this case is the identification of the magnetic sensors (31) with respect to which there is a magnetic active zone (21m). The anatomical data is the trajectory (T) of the root canal (11), in three dimensions.

[0085] The resolution of the matrix (32) can be adapted according to the size of the magnetic sensors (31) used. Miniaturized sensors that increase the resolution of the matrix (32) are preferred.

[0086] Figure 5 illustrates a trajectory (T) of the root canal (11), obtained by implementing the preferred embodiment. Although the cross-section (S) of the root canal (11) is not provided, the presence of the curves (C) is detected, and the practitioner can prepare their intervention accordingly.

[0087] One method of implementing the preferred embodiment of [Fig.4] may also consist of manipulating the file (20) within the root canal (11), so that the file (20) occupies different positions within the canal.

[0088] Indeed, when the file (20) has an external diameter that is less than the internal dimensions of the root canal (11), it is possible to insert it, preferably at the working length (Lt), and then manipulate it so that each active zone (21), at its depth, sweeps the entire section (S) of the root canal (11).

[0089] For each depth of each of the active zones (21), the acquisition device (30) acquires the several positions occupied by the active zone (21). From these several positions, the processing unit (40) is programmed to determine the cross-section (S) of the root canal (11) at each depth of each of the active zones (21).

[0090] From each of the sections (S) obtained, the processing unit (40) is programmed to determine the geometry (G) of the root canal (11).

[0091] The method implemented is based on the principle of continuity of the internal surface of the root canal (11), between two successive sections (S).

[0092] The above method can also work when the file (20) comprises only a single magnetic active zone (21m). In this case, the file (20) must be manipulated at different depths so that the active zone (21m) can provide position data for sections (S) at different depths of the canal. Advantageously, the single magnetic active zone is located on or near the tip (24).

[0093] In a second embodiment, not shown, the file (20) comprises an optical fiber (25) and no magnetic active areas (21m). In this case, the active area (21) comprises a first end (25i) of the optical fiber (25) which terminates at the tip (24) of the file (20). A second end (25o) of the optical fiber (25) is connected to an optical sensor of the acquisition means (30).

[0094] In this embodiment, the active zone (21) therefore provides position data by optical radiation.

[0095] The optical fiber (25) is preferably used as a transmit-receive means, that is to say, the same optical fiber (25) carries light in the direction of the first end (25i) to illuminate the inside of the root canal (11), then conveys light reflected by the internal surface of the root canal (11) towards the acquisition means (30).

[0096] The acquisition means (30) acquire images, which are then analyzed by the processing unit (40) to determine the geometry (G) of the root canal (11), according to the same principle of surface continuity mentioned above. In this case, the acquisition of the geometry (G) of the internal surface of the root canal (11) occurs progressively as the file (20) moves within the root canal (11).

[0097] The acquisition of position data is preferably carried out within a dry root canal (11), so that the acquisition is as little disturbed as possible, but this is not imperative.

[0098] Within an untreated root canal (11), the tissues are soft and very aqueous: although the aqueous environment slightly distorts the optical signal, acquisition of position data by the optical fiber (25) is possible within the untreated root canal (11).

[0099] Indeed, the distance separating the optically active zone (21o) and the internal wall of the root canal (11) is very short, on the order of a few hundredths of a millimeter to a few tenths of a millimeter. The signal distortion is minimal, and therefore does not prevent its use for determining the geometry (G) of the canal.

[0100] Optical acquisition begins when the file (20) is inserted into the root canal (11), and the processing unit (40) determines the geometry (G) of a first portion of the root canal (11) with respect to the first end (25i) of the optical fiber (25).

[0101] The file (20) is then inserted deeper into the canal so that a subsequent portion of the root canal (11), contiguous to the first portion, is in view of the first end (25i) of the optical fiber (25).

[0102] The processing unit (40) determines what the geometry (G) of this next portion is, and reconstructs the geometry (G) of the root canal (11) by continuity of surfaces between the first portion and the next portion.

[0103] This operation is repeated as many times as necessary until the entire geometry (G) of the root canal (11) is determined.

[0104] Within a system defined by the root canal (11) and the acquisition means (30), the position data in this case is the distance of points on the internal wall of the root canal (11) from the optical active zone (210). The anatomical data is the geometry (G) of the root canal (11).

[0105] A high-performance transmission-reception technology for implementing methods of acquiring surface geometry (G)s is the "LIDAR" technology, according to the English "light detection and ranging".

[0106] The file (20) may include several optical fibers (25), so that several active areas (21) are arranged on a periphery of the file (20) and allow observation of an angular sector of the root canal (11).

[0107] For example, three optical fibers can all emerge at the same distance from the tip (24) of the file (20), each first end of each file (20) being arranged at 120° to each other.

[0108] In this way, a larger number of images are acquired at the same time, at a given depth.

[0109] Preferably, the number of optical fibers (25) is sufficient to simultaneously acquire the entire portion of the root canal (11), that is to say the whole circumference of the root canal (11), at a given depth.

[0110] However, current optical fibers (25) have an external diameter of approximately 0.15 mm, so that an optical fiber (25) can obtain the geometry (G) of the majority of root canals, but is not suitable for the finest root canals. The optically active zone (21o) is positioned as close as possible to the tip (24) of the file (20), in order to allow image acquisition as far as possible within the root canal (11).

[0111] To overcome this disadvantage of excessive size, a third embodiment, illustrated in [Fig.7], combines the first and second embodiments: the file (20) includes both magnetic active zones (21m) with different magnetism, and an optical fiber (25) whose first end (25i) opens at the level of an optical active zone (21o).

[0112] The optical fiber (25) is used for a proximal part of the root canal (11) whose diameter is sufficiently large, and the magnetic active areas (21m) are used for at least a distal part of the root canal (11), located between the proximal part and the apex (13), and are preferably used over the entire root canal (11).

[0113] In this embodiment, the active zones (21) therefore provide position data by electromagnetic radiation as well as by optical radiation.

[0114] Advantageously, the processing unit (40) combines position data: - acquired by electromagnetic radiation, using magnetic active zones (21m), and - acquired by optical radiation, by means of the optical active zone (21o) or optical active zones (21o).

[0115] This complementarity of the positional data used makes it possible to improve the accuracy and reliability of the anatomical data acquired.

[0116] Alternatively, the acquired images may only be used for visual verification by the practitioner, checking for example the presence or absence of bifurcations within the root canal (11).

[0117] The determination of the anatomical data can be done in real time, but it can also be done a posteriori. In this case, the processing unit (40) is configured to determine the anatomical data from previously obtained positional data.

[0118] This embodiment can be adapted when the processing unit (40) executes a program with a long execution time.

[0119] This embodiment is also suitable for improving the computer program that the control unit executes: it may be useful to save raw, unprocessed position data to serve as training data for further improvements to the computer program.

[0120] Such raw data can also serve as training data for an artificial intelligence programmed to determine anatomical data of root canals (11).

[0121] The device can be shaped differently from the figures without going out of the scope of the invention, which is defined by the claims.

[0122] In a particular embodiment, the magnetically active area (21m) of the file (20) is formed by the entire blade, and the passive area (22) is formed by the handle (23) of the file (20). The entire blade can be detected by the magnetic sensors (31). This embodiment is suitable for blades made from steel.

[0123] Regardless of the embodiment implemented, the device according to the invention can be used during treatment, in order to replace an apex locator (13)

[0124] In particular, an alternative embodiment provides that there is only one magnetic sensor (31), positioned by the practitioner opposite the apex (13) of the root canal (11). The position of the apex (13) is determined beforehand using the diagnostic radiograph, as well as the working length (Lt) obtained using an apex locator. A magnetic active zone (21m) is placed at the tip (24) of the file (20).

[0125] This minimalist device makes it possible to know, during treatment, whether the tip (24) of the file (20) has reached the apex (13) or not. This embodiment avoids the risk of overshooting the apex (13) and perforation, which could occur with an apex locator (13) due to the poor quality of the signal it provides during treatment.

[0126] Within a system defined by the root canal (11) and the acquisition means (30), the position data in this case is the presence or absence of the magnetic active zone (21m) with respect to the magnetic sensor (31), and the anatomical data is the presence of the tip (24) of the file (20) at the level of the apex (13) of the root canal (11).

[0127] An improvement to this minimalist device includes several magnetic sensors (31) arranged along an axis configured to be arranged substantially parallel to a general direction (D) of the root of the tooth (10), from the pulp chamber (14) to the apex (13).

[0128] As the file (20) progresses within the root canal (11), the magnetic sensors (31) become active. It is therefore possible to monitor the working depth of the file (20) as it progresses, in order to predict its arrival at the apex (13). This anticipation is preferable to only having information when the tip (24) of the file (20) has reached the apex (13).

[0129] Within a system defined by the root canal (11) and the acquisition means (30), the position data in this case is the identification of the magnetic sensor (31) with respect to which the magnetic active zone (21m) is located. The anatomical data is the position of the tip (24) of the file (20) within the root canal (11), i.e., the working depth.

[0130] A modification of the first embodiment provides that there is only one magnetic active zone (21m) located at the tip (24) of the file (20). When the file (20) is inserted into the root canal (11), the magnetic active zone (21m) is detected successively by different magnetic sensors (31), which allows the control unit (40) to reconstruct the profile (P) or the trajectory (T) of the canal, depending on whether there is one or two arrays (32) of magnetic sensors (31).

[0131] Regardless of the embodiment implemented, it is possible to acquire the geometry (G) of the root canal (11) in several stages during treatment: - the practitioner acquires the geometry (G) of a first portion of the root canal (11), then treats the first portion, - then the practitioner acquires the geometry (G) of a second portion of the root canal (11), then treats the second portion, - and so on until the root canal (11) is treated to the working length (Lt).

[0132] Furthermore, the technical characteristics of the various embodiments and variants mentioned above can be combined, in whole or in part. Thus, the device and the file (20) can be adapted in terms of cost, functionality, and performance.

Claims

Demands

1. Device for endodontic treatment of a root canal (11) of a tooth root (10) of a patient, comprising: - an instrumented file (20) comprising a passive zone (22) and an active zone (21), the active zone (21) having a different magnetism from that of the passive zone (22) and being configured to provide position data by electromagnetic radiation, - acquisition means (30) comprising a sensor (31), and configured to acquire position data within a system defined by the root canal (11) and the acquisition means (30), and - a treatment unit (40) connected to the acquisition means (30), characterized in that the treatment unit (40) is configured to process the position data of the active zone (21) within the system, in order to determine an anatomical datum of the root canal (11),for example a trajectory (T) of the root canal (11) or that an apex (13) of the root canal (11) is reached by a tip (24) of the file (20), and wherein the acquisition means (30) comprise several magnetic sensors (31) arranged along an axis configured to be placed in a vestibule of the patient and to be arranged substantially parallel to a general direction (D) of the root of the tooth (10), from a pulp chamber (14) of the tooth (10) to the apex (13) of the root canal (11).

2. Device according to claim 1, wherein the file (20) comprises several active zones (21).

3. Device according to claim 1 or 2, wherein the acquisition means (30) comprise an array (32) of sensors (31): - the array (32) defining a plane in which the sensors (31) are distributed so as to define a two-dimensional system, and - the array (32) being configured to be arranged substantially parallel to the general direction (D) of a root of the tooth (10), and extending from a pulp chamber (14) of the tooth (10) to an apex (13) of the canal.

4. Device according to claim 3, wherein the acquisition means (30) comprise two arrays (32) of sensors (31) configured to be arranged in two non-parallel planes.

5. Device according to any one of claims 3 or 4, wherein the processing unit (40) is programmed to: - acquire several position data when the file (20) is manipulated within the root canal (11), at a given depth within the root canal (11), - from the several position data of a given depth, determine a section (S) of the root canal (11) at that depth.

6. Device according to any one of the preceding claims, wherein an active area (21) is configured to provide position data by optical radiation, and comprises a first end (25i) of an optical fiber (25) which emerges at the tip (24) of the file (20), and a second end (25o) of the optical fiber (25) is connected to the sensor (31) which is an optical sensor.

7. Device according to claim 6, wherein the optical sensor (31) is a laser remote sensing transceiver.

8. Instrumented file (20), configured to cooperate with the device according to any one of the preceding claims, the file comprising a passive area (22) and an active area (21), the active area (21) being configured to provide position data by electromagnetic radiation.

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