ORTHODONTIC WIRE BENDING DEVICE AND METHOD

Abstract

An orthodontic wire bending device including a wire guiding unit and a wire bending unit; the wire guiding unit including a convoying system and an exit, and the wire bending unit including at least one wire bending member able to turn around a center of rotation, such that, when the wire comes out of the exit of the wire guiding unit a rotation of the at least one of the bending members around the center of rotation results in the bending of the wire.

Claims

1-20. (canceled)

21. A Orthodontic wire bending device comprising: a wire guiding unit comprising a convoying system for driving the wire and an exit for delivering the wire, the wire guiding unit being configured to guide the wire in a first direction along a longitudinal axis through the exit, and a wire bending unit fed by the wire delivered by the exit, comprising at least one wire bending member, the at least one wire bending member being able to turn around a center of rotation in a first plane including the longitudinal axis, such that, when the wire comes out of the exit, a rotation of the at least one bending members around the center of rotation results in the bending of the wire proximate to the exit, wherein the exit of the wire guiding unit is located, along the first direction, beyond the center of rotation.

22. The orthodontic wire bending device according to claim 21, wherein the exit is a nozzle.

23. The orthodontic wire bending device according to claim 21, configured such that a rotation of the at least one bending member of an angle ? results in the bending of the wire after elastic recovery of an angle ? wherein the relationship between ? and ? is given by equation: $\begin{array}{cc}\tan \left(?\right)=\frac{\sin \left(?\right)}{\cos \left(?\right)-\frac{d}{R}}& \left(e1\right)\end{array}$ in which d is the distance between the center of rotation and the exit, and R is the distance between the center of rotation and the at least one wire bending member.

24. The orthodontic wire bending device according to claim 21, wherein the convoying system is capable of rotating about the longitudinal axis, so as to rotate the wire about the longitudinal axis.

25. The orthodontic wire bending device according to claim 21, wherein the wire guiding unit comprises a tube configured to house and guide the wire.

26. The orthodontic wire bending device according to claim 25, wherein the tube comprises: an external cover and an inner sheath.

27. The orthodontic wire bending device according to claim 21, wherein the exit has an inner surface having an inner radius, an outer surface, and a bevel or round extending from the inner surface to outer surface, the bevel or round having a radius of curvature r which is equal or greater than the inner radius Dt/2.

28. The orthodontic wire bending device according to claim 21, wherein the wire bending unit comprises a plate capable of rotating about an axis of rotation perpendicular to the longitudinal axis, wherein the at least one bending member protrudes from said rotating plate.

29. The orthodontic wire bending device according to claim 21, wherein the wire guiding unit comprises a hollow body having a proximal end and a distal end, the hollow body being non-rotatably connected to the convoying system and being configured to receive, at its proximal end, the wire from the convoying system and to guide it along the first direction towards the wire bending unit.

30. The orthodontic wire bending device according to claim 21, wherein the at least one bending member is a bending rod.

31. The orthodontic wire bending device according to claim 21, wherein the bending rod has a diameter which decreases along the protruding direction.

32. The orthodontic wire bending device according to claim 21, wherein the wire bending unit further comprises a wire cutting member.

33. The orthodontic wire bending device according to claim 21, wherein the wire bending unit comprises one bending member.

34. The orthodontic wire bending device according to claim 21, wherein the wire bending unit comprises one bending member capable of a translation along a direction perpendicular to the first plane.

35. The orthodontic wire bending device according to claim 33, wherein the convoying system is capable of a rotation about the longitudinal axis larger than 180?, so as to provide a second order bending.

36. The orthodontic wire bending device according to claim 21, wherein the wire bending unit comprises two bending members.

37. The orthodontic wire bending device according to claim 36, wherein the convoying system is capable of a rotation about the longitudinal axis of an angle comprised between 0? and 180?, so as to provide a second order bending.

38. An orthodontic wire bending system comprising: a. an orthodontic wire bending device according to claim 21, the orthodontic wire bending device being responsive to control commands; b. a driver assembly comprising a first driver operably connected to the wire guiding unit and configured to drive the wire in the guiding unit, and a second driver operably connected to the wire bending unit configured to drive in rotation the at least one bending member; and c. a programmable controller configured to send control commands to the drivers of the driver assembly, so as to operate the orthodontic bending device.

39. The orthodontic wire bending system according to claim 38, further comprising a wire detection unit for detecting the presence of the wire.

40. A method of manufacturing an orthodontic archwire with the orthodontic wire bending device according to claim 21, the method comprising: guiding the wire through the wire guiding unit in a first direction along the longitudinal axis, and delivering the wire out of the wire guiding unit through the exit; feeding the wire bending unit with the wire delivered from the exit; and rotating the at least one bending member of a predefined angle ? around the center of rotation so as to bend the wire.

Description

DETAILED DESCRIPTION

[0064] The following detailed description will be better understood when read in conjunction with the drawings. For the purpose of illustrating, the device is shown in the preferred embodiments. It should be understood, however that the application is not limited to the precise arrangements, structures, features, embodiments, and aspect shown. The drawings are not drawn to scale and are not intended to limit the scope of the claims to the embodiments depicted. Accordingly, it should be understood that where features mentioned in the appended claims are followed by reference signs, such signs are included solely for the purpose of enhancing the intelligibility of the claims and are in no way limiting on the scope of the claims.

[0065] The present invention relates to an orthodontic wire bending device 1 comprising a wire guiding unit 2, and a wire bending unit 3, as shown in FIGS. 2, 3 and 7.

[0066] In the following detailed description, the term proximal refers to an element, or the extremity of an element, which is closer to the wire guiding unit 1; whereas the term distal refers to an element, or an element extremity, which is closer to wire bending unit 3.

[0067] In the present invention, the wire guiding unit 2 comprises a convoying system 21 for driving the wire, and an exit 22 for delivering the wire. The wire guiding unit 2 is configured to guide the wire in a first direction (represented by the white arrow in FIG. 2) along a longitudinal axis x through the exit 22.

[0068] The wire bending unit 3 is configured to receive the wire w delivered by the exit of the wire guiding unit 2. Said wire bending unit 3 comprises at least one wire bending member 31, 32, which is capable of rotating around a center of rotation C in a first plane P including the longitudinal axis x. In other words, the axis of rotation passing through C of the bending member is perpendicular to the plane P, and C is on the longitudinal axis x.

[0069] When the wire comes out of the exit 22, a rotation of the at least one bending member 31, 32 around the center of rotation C results in the bending of the wire w.

[0070] The wire advances through the device in a stepwise manner from the wire guiding unit 2 towards the wire bending unit 3, along the longitudinal axis x. After an advancement step, the wire is bent at the wire bending unit 3 of a first bending angle ?. At the next advancement step, the wire may be bent at the wire bending unit 3 of a second bending angle, and so on, until the desired archwire shape is obtained.

The Device

[0071] As illustrated in FIG. 3, the wire guiding unit 2 comprises a convoying system 21 for driving the wire w, and an exit 22 for delivering the wire.

[0072] In the wire guiding unit 2 illustrated in FIG. 3, the exit 22 is a nozzle. More in particular, the exit 22 is a nozzle having the shape of a composite solid: a proximal hexagonal prism and a distal cone; the hexagonal prism allowing to screw efficiently the nozzle on the device. In another embodiment, the exit 22 is a nozzle having a proximal cylindric shape and a distal cone; mounted with a pressure screw.

[0073] The convoying system 21 may comprise a pair of rollers, or gears, capable of rotating about an axis perpendicular to the longitudinal axis x, so that, when the wire w passes in between the two rollers, the rotation of the rollers results in the wire advancement. Several transmission systems may be used to drive the rollers, or gears, in rotation: for instance, a driver may be connected to a driving gear via a shaft, or the rollers may be belt-driven. Throughout this disclosure, drivers may be advantageously motors.

[0074] FIG. 3 represents a perspective view of the wire guiding unit 2 of the present invention according to one particular embodiment in which the convoying system 21 comprises a driving roller 211, a driven roller 212, a driver 213 connected to the driving roller 211 and configured to drive the rollers 211, 212 in rotation, and a tube 214 placed upstream of said rollers.

[0075] In some embodiments, the wire guiding unit 2 comprises a tube 214 configured to house and guide the wire; which may be installed upstream, downstream of the convoying system 21, or inside the convoying system 21.

[0076] In one embodiment, the convoying system 21 is capable of rotating about the longitudinal axis x, so as to rotate the wire w about the axis x.

[0077] One example of a rotatable convoying system 21 according to the present invention is illustrated in FIG. 3. In this embodiment, the convoying system 21 is capable of rotating about the longitudinal axis x, as it can be driven in rotation by a belt and pulley assembly 215, connected to a driver 216. The convoying system 21 therein illustrated comprises a support element 217 on which the rollers 211, 212 and the driver 213 are mounted. The support element 217 is connected to the belt and pulley assembly 215 and it has the twofold function of bearing the rollers 211, 212 and the driver 213, and permitting the rotation of the convoying system 21 about the axis x.

[0078] With such a rotatable convoying system 21 it is possible to simultaneously translate the wire along the longitudinal axis x, and rotate it about said axis.

[0079] If the convoying system 21 is driven in rotation about the longitudinal axis x during the wire advancement, consecutive bending angles ? do not lie on the same bending plane. Thus, the rotation of the convoying system 21 allows to modify the bending plane at each advancement step of the wire, so as to provide a second order bending.

[0080] Advantageously, the total length to be covered by the wire is also reduced, because the wire translation and rotation are simultaneously obtained inside the wire guiding unit 2. With this embodiment, it is therefore possible to reduce the dimensions of the orthodontic wire bending device 1.

[0081] This would not be possible in a wire bending device in which the wire advancement and the wire rotation about the advancement direction are provided by separated components.

[0082] In one embodiment, the convoying system 21 is capable of rotating about the longitudinal axis x up to an angle of 180?, preferably of at least an angle of 180?, more preferably of at least an angle of 360?. A rotation angle equal or greater than 360? is especially interesting in a configuration with only one bending member. One example of this embodiment is illustrated in FIGS. 4A and 4B. In FIG. 4A, the wire guiding unit 2 is represented in a first position in which the rotation angle of the convoying system 21 is 90?, and in FIG. 4B it is represented in a second position in which the rotation angle is 180?.

[0083] As aforementioned, the wire guiding unit 2 may comprise a tube 214 configured to house and guide the wire. Preferably, the tube 214 is made up of a metal or a metal alloy; more preferably, a medical grade metal or metal alloy.

[0084] Examples of suitable metals or a metal alloys comprise: stainless steel, aluminum, cobalt-chrome alloy, titanium, nickel-titanium alloy (nitinol). Preferably, the external cover is made up of a medical grade metal or alloy material.

[0085] In one embodiment, the tube 214 comprises an external cover and an inner sheath.

[0086] In one embodiment, the external cover is made up of a metal or a metal alloy.

[0087] In one embodiment, the inner sheath is a polymeric sheath.

[0088] In one embodiment, the inner sheath is made up of a thermoplastic elastomer, such as for instance thermoplastic urethane (TPU) elastomer, thermoplastic elastic olefin (TEO), styrene-ethylene-butylene-styrene (SEBS), polyether-ester block copolymers (COPE), thermoplastic polyether block amide (PEBA), or a combination thereof.

[0089] Preferably, the thermoplastic elastomer is a medical grade thermoplastic elastomer.

[0090] The wire guiding unit 2 may further comprise a hollow body 218 having an external surface and an internal surface defining an internal hollow portion. The hollow body 218 extends, along a direction parallel to the longitudinal axis x, from the convoying system 21 to the exit 22 so that the wire exiting from the convoying system 21, it enters the hollow body 218, it advances inside the internal hollow portion, and it is delivered to the exit 22 of the wire guiding unit 2. Here, the wire is exposed to the wire bending unit 3 and it can be bent by the bending member 31, 32.

[0091] In one embodiment, the hollow body 218 is made up of a metal or alloy material.

[0092] Metal or alloy materials prevent rotational friction that might result from rotation of the wire relative to the inner surface of the hollow body 218. This friction may increase the risk of crack formation, and cause energy losses.

[0093] In the invention, the wire guiding unit 2 comprise an exit 22 which is located, along the first direction, beyond the center of rotation C of the bending member 31, 32.

[0094] This set-up presents several advantages: [0095] The distance between the bending member and the exit of the nozzle may be very small. This distance defines the characteristic length of shape change along the archwire. A small characteristic length allows to increase resolution of archwire shape and precision of archwire geometry. [0096] A small rotation angle of bending member corresponds to a large angular bending of wire, giving access to highly bent archwire structures. [0097] As bending member is very close to the exit of the nozzle, the momentum exerted on the wire is amplifiedlever arm effect.

[0098] In one embodiment, the exit 22 is a nozzle, preferably a removable nozzle. This embodiment allows to employ different nozzles having different cross-sections. It is therefore possible to selected the nozzle whose cross-section is optimized to the cross-section of the wire being used and/or to the archwire shape to be obtained.

[0099] In one embodiment, the inner surface of the exit 22 has a circular or elliptical cross-section, as shown in FIG. 5.

[0100] In one embodiment, the exit 22 has an inner surface which is beveled or rounded, i.e. filleted on an exterior corner.

[0101] The presence of the bevel or round ensures that the wire, during bending, does not face sharp edges. Sharp edges may cause surface defects such as wrinkles in the inside bend of the wire w.

[0102] The exit 22 may have an inner surface having an inner diameter Dt, an outer surface. By having an inner surface which is beveled or rounded, it is meant that a bevel or rounded extends from the inner surface to the outer surface, with a radius of curvature r. Preferably, the radius of curvature r is equal or greater than the radius of the inner surface Dt/2, preferably equal or greater than the diameter of the inner surface Dt. Indeed, to avoid stress in bent wire, it is preferable that the radius of curvature of the bent wire be larger than the radius of the wire itself. When the radius of curvature of the bent wire is larger than the diameter of the wire itself, risk of breakage of archwire due to fatigue wear is reduced.

[0103] In one embodiment, the radius of curvature r of the round is constant.

[0104] Alternatively, the radius of curvature may be variable. For instance, the exit 22 of FIG. 6 is a nozzle whose inner surface has a squared cross-section, in which two opposite sides are not beveled, i.e. they have a zero radius of curvature, and the other two opposite sides are rounded, i.e. they have a non-zero radius of curvature. The radiuses of curvature of the rounded sides may be identical or, as illustrated in FIG. 6B, may differ. In this particular embodiment, the radius of curvature r.sub.R of the right-side round is larger than the radius of curvature r.sub.L of the left side round.

[0105] Having a variable radius of curvature allows to obtain, with a single exit 22, different bend radius. For instance, with the nozzle of FIG. 6, it is possible to provide smaller bend radius by using the bending member 31, 32 which would bend the wire w toward the left side of the exit 22, and larger bend radius by using the bending member 31, 32, as it would bend the wire toward the right side of the exit 22.

[0106] In one embodiment, the inner surface of the exit 22 has a square or rectangular cross-section, as shown in FIG. 6.

[0107] If the cross-section of the inner surface is not circular, by inner diameter Dt it is meant the shortest dimension of the cross-section, for instance the length of one side for a square cross-section, or the minor axis for an elliptical cross-section.

[0108] In one embodiment, the exit 22 is tapered, i.e. it has an inner surface having a constant inner diameter Dt, and an outer surface having an outer diameter which decreases along the first direction. Examples of this embodiment are visible in FIGS. 5 and 6. In these embodiments, the exit 22 has a hollow frustoconical shape.

[0109] The orthodontic wire bending device 1 according to the present invention further comprises a wire bending unit 3 configured to receive the wire w delivered by the exit 22 of the wire guiding unit 2 and comprising at least one bending member 31, 32.

[0110] In a first configuration, the wire bending unit 3 comprises two bending members 31, 32. One example of this embodiment is shown in FIG. 8A-B

[0111] In a wire bending unit 3 comprising two bending members 31, 32, a rotation of the convoying system 21 of an angle comprised between 0? and 180? is sufficient to provide a second order bending. Such a small rotation of the two bending members 31, 32 allows to render the convoying system 21 less complex and more stable.

[0112] In a second configuration, the wire bending unit 3 may comprise only one bending member 31, 32. One example of this embodiment is shown in FIG. 8C.

[0113] In a wire bending unit 3 comprising only one bending member 31, 32, the convoying system 21 is preferably capable of a rotation larger than 180?, and more preferably larger than 360?. Such a large rotation advantageously allows to access totally the 3D space for all orientations of the archwire under formation. Therefore, second order bending becomes more accessible.

[0114] The wire bending unit 3 of the first configuration is better shown in FIG. 7. In this particular embodiment, the two bending members 31, 32 may be mounted on the same support capable of rotating around the center of rotation C. Having the bending members 31, 32 mounted on the same support allows to reduce the dimensions of the bending unit 3. Alternatively, the two bending members 31, 32 may be mounted on two distinct supports.

[0115] The support on which the at least one bending member 31, 32 is mounted, may be driven in rotation by a driver 35, as shown in FIG. 7.

[0116] In one embodiment, the support is a plate 33.

[0117] In the embodiment illustrated in FIG. 7, the bending members 31, 32 are rods perpendicularly protruding from the plate 33.

[0118] In one embodiment of the first configuration, the angular distance between the two bending members 31, 32 is comprised between 10? and 170?. Preferably, the angular distance between the two bending members 31, 32 is comprised between 45? and 120?; more preferably, it is equal to 90?.

[0119] Advantageously, the combination of: (i) the angular distances between the bending members 31, 32 and (ii) the diameter of said bending members 31, 32, allows to obtain an archwire which reproduces the shape of the interproximal space, indicated by the white arrows in FIG. 9. Indeed, the contour of the teeth comprises a series of concavities and convexities which are smooth on the surface of the teeth. In the interproximal spaces, such concavities and convexities become harsh, and the contour of the teeth displays sharper angles. Most archwire reproduce the contour of each tooth with sufficient fidelity, but they are unable to fit inside the interproximal spaces, because of the difficulty of obtaining such sharp angles with the conventional archwire manufacturing process. As it can be appreciated in FIG. 9, the archwire obtained with the present invention is a three-dimensional archwire.

[0120] Inversely, in the present invention, the angular distance between the bending members 31, 32 and their shape allows to accurately reproduce such interproximal spaces, without creating surface defects (such as wrinkles) on the wire w.

[0121] By providing two bending members 31, 32 it is possible to bend the wire of large bending angles ?, while reducing the angular displacements ? of the bending members 31, 32 and the number of degrees of freedom (DOFs) of the bending unit 3. Advantageously, by limiting the number of DOFs it is possible to reduce the complexity and the cost of the drivers associated to the bending unit 3. Furthermore, less DOFs generate less disturbances (such as backlashes, which may negatively affect the stability of the bending unit 3) and make it easier to control the bending force.

[0122] The reference position of the plate 33 may be defined as the position in which the two wire bending members 31, 32 are at the same distance from the exit 22.

[0123] The wire bending unit 3 of the second configuration comprises only one bending member 31, 32 (for instance, only the first bending member 31).

[0124] In this case, a larger rotation (e.g., a whole clockwise rotation, depending on the desired final shape of the wire w) of the bending member 31 may be necessary in order to bend the wire w in a direction opposite to the direction of the preceding bending.

[0125] In addition, the bending unit 3 may be configured to ensure the translation of the bending member 31 in a direction perpendicular to the plane of the rotation (e.g., in a vertical direction for a horizontal plane of rotation). Advantageously, this embodiment allows to bend a first side of the wire, then to displace the bending member 31 away from the bent side, and displace it in proximity of the other side of the wire w, along a trajectory which is shorter than a whole rotation. In other words, this embodiment allows to shorten the trajectory of the bending member 31 between the first side and the other side of the wire w (and, accordingly, to provide a faster bending of the wire w) by providing a bending unit 3 which has a higher number of degrees of freedom (DOFs). In particular, in this case the bending unit 3 has two DOFs so as to ensure: (i) the rotation around the center C and (ii) the translation, for instance along a vertical direction, of the bending member 31.

[0126] The reference position of the plate 33 may be defined as the position in which said bending member 31, 32 faces the exit 22.

[0127] In both configurations, the plate 33 is capable of rotating around a vertical axis z which is perpendicular to the longitudinal axis, and which includes the center of rotation. The bending

member 31, 32 may be mounted so that it protrudes from a surface of the plate 33. Thus, a rotation of the plate about the vertical axis results in the rotation of the bending member 31, 32 around the center of rotation C. One example of this embodiment is illustrated in FIG. 2. In this embodiment, two wire bending members 31, 32 are provided as cylindrical rods which protrude perpendicularly from the plate.

[0128] In one embodiment, the plate 33 is capable of rotating about the vertical axis z of an angle up to 180?.

[0129] In one embodiment, the plate 33 is capable of a clockwise rotation up to 90? and a counterclockwise rotation up to 90?, from the reference position.

[0130] As aforementioned, the first plane P includes the longitudinal axis x.

[0131] The plane P is better shown in FIG. 8, which illustrates a simplified top view of the wire guiding unit 2 and the wire bending unit 3 of the present invention on the plane P. The angles ? and ?, the distance R between the center of rotation C and the wire bending members 31, 32, and the distanced between the center of rotation C and the exit are also represented.

[0132] As shown in shown in FIG. 8, when the wire w comes out of the exit 22, a rotation of at least one of the bending members 31, 32 around the center of rotation C results in the bending of the wire w.

[0133] More in particular, the wire w advances through the device in a stepwise manner from the wire guiding unit 2 towards the wire bending unit 3, along the longitudinal axis x. After an advancement step, the wire w is bent at the wire bending unit 3. Indeed, the rotation of the wire bending member 31, 32 of an angle ? results in the bending of the wire of a bending angle ?, and the relationship between the angles ? and ? is given by equation e1:

[00002]$\begin{array}{cc}\tan \left(?\right)=\frac{\sin \left(?\right)}{\cos \left(?\right)-\frac{d}{R}}& \left(e1\right)\end{array}$

[0134] By bending angle ?, it is meant the angle between the longitudinal axis x and the bent portion of the wire, which has as vertex the exit of the wire guiding unit 1. Actually, wire bending is a sum of elastic deformation and plastic deformation, only the latter remaining after elastic recovery when bending member is withdrawn. Equation (e1) holds true as far as bending member is in contact with the wire: when bending member applies a force onto the wire; and when the wire is recovering elastically while the bending wire is withdrawn. When the bending member loses contact with the wire during withdrawal, angle ? of bending is defined with the angle ? related to the position of the bending member at this instant. So as to reach a bending angle ? for the wire, bending member has to reach an angle larger than angle ? defined by equation (e1). Equation (e1) corresponds to the geometry of bend after elastic recovery.

[0135] At the next advancement step, the wire may be bent at the wire bending unit 3 of a second bending angle, and so on, until the desired archwire shape is obtained.

[0136] As shown in FIG. 8, in the present invention, the exit 22 of the wire guiding unit 2 is located, along the first direction, beyond the center of rotation C.

[0137] Therefore, according to a coordinate system originating in the center of rotation C, and having as horizontal axis the longitudinal axis x, the abscissa of the exit 22 is positive.

[0138] Advantageously, this embodiment allows to minimize the distance between the exit 22 of the wire guiding unit 2 and the bending member 31, 32. Thus, for a given bending moment, the force applied by the bending member 31, 32 to the wire w is maximized.

[0139] The presence of two bending members 31, 32 in the first configuration allows to obtain large bending angles ? with small angular displacements ? of the bending members 31, 32. In the example illustrated in FIG. 8, the bending members 31, 32 are rotated in a counterclockwise manner to bend the wire and pass from FIG. 8A to FIG. 8B, so that the wire can be bent by the first bending member 31. From the configuration of FIG. 8B, to bend the wire in the opposite direction, it is sufficient to rotate the bending members 31, 32 in a clockwise manner, so as to bend the wire with the second bending member 32.

[0140] As aforementioned, the bending member 31, 32 is able to turn around a center of rotation C in the first plane P. In other words, the axis of rotation passing through C of the bending member is perpendicular to the plane P and preferably, center of rotation C is on the longitudinal axis x. Advantageously, having the rotation of the bending member 31, 32 in the plane P, which includes the longitudinal axis x, allows to reduce the dimensions of the wire bending unit 3. Furthermore, it allows to bend the wire w more rapidly, when compared to a coaxial bending unit, i.e. a bending unit in which the bending member rotates in a plane perpendicular to the plane in which the longitudinal axis lies.

[0141] Indeed, a coaxial bending unit would require a large distance between the center of rotation C and the bending member 31, 32, because the wire guiding unit 2 indeed would act as a physical obstacle, precluding the possibility to have the bending member proximate to the exit 22.

[0142] A large distance between the center of rotation C and the bending member 31, 32, should be avoided because (i) the bending unit 3, and hence the orthodontic wire bending device 1, would occupy a large volume and (ii) the bending member 31, 32 would require more time to reach the wire to be bent.

[0143] The rotation of the support of the bending unit 3, allows to move the wire bending member 31, 32 along a circular arc trajectory. In FIG. 8, the dashed line represents a portion of the trajectory which can be covered by the bending members 31, 32.

[0144] The diameter of the bending member 31, 32 is comprised between 0.1 mm and 100 mm, preferably between 0.1 mm and 10 mm.

[0145] Preferably, the diameter of the bending member 31, 32 is at least 0.3 mm.

[0146] In one embodiment, the diameter of the bending member 31, 32 is comprised between 0.3 mm and 5 mm. Such diameters allow to obtain small inside bend radius, which are especially needed to reproduce the contour of the interproximal space i.e., the space between adjacent teeth in a dental arch.

[0147] In one embodiment, the bending member 31, 32 has a conical shape.

[0148] In one embodiment, the bending member 31, 32 has a cylindrical shape.

[0149] In one embodiment, the bending member 31, 32 has the shape of a composite solid. The edges shared by adjacent solids may be beveled, as illustrated for instance in FIG. 10.

[0150] The decreasing diameter allows to provide a bending member 31, 32 which has a smaller diameter at its free end, and which has a larger diameter at its base. Advantageously, this embodiment allows to obtain all the relevant archwire shapes, while ensuring mechanical stability to the bending member 31, 32, due to the larger base. Besides, centering, effort transfer from device to bending member, stability of geometry are improved with a larger base. This specific structure allows a better distribution of bending moment and limit the deflection of the bending member on one hand and limits misalignments, parallelism defects or contact defects between the bending member and the wire.

[0151] In one embodiment, the two bending members 31, 32 have the same shape.

[0152] In one embodiment, the two bending members 31, 32 have different shapes.

[0153] In the examples illustrated in FIG. 10, the bending members 31, 32 protrude from a rotating plate 33, and their diameter decreases along the protruding direction. More in particular, these bending members 31, 32 have the shape of a composite solid comprising, along a direction protruding from the rotating plate 33: a first cylinder, a truncated cone, and a second cylinder, with a diameter smaller than that of the first cylinder.

[0154] In one embodiment, the bending member 31, 32 is not detachable from the rotating support. For instance, it may have an extremity which is embedded in the rotating support, it may be integrally manufactured with the rotating support or it may be attached to it.

[0155] In one embodiment, the bending member 31, 32 is removable, i.e., it can be detached from the rotating support. For instance, they may have an extremity which is screwed, or snap-fitted in the rotating support; or they may be mounted on the rotating support with any other reversible attachment method.

[0156] Advantageously, this embodiment allows to remove and replace the bending members 31, 32. Different bending members 31, 32 having different shapes can be used. Of note, the types and number of final archwire shape which can be obtained depends on the shape of the bending members 31, 32. Therefore, with this embodiment it is possible to use the same orthodontic bending device 1 for manufacturing a wide number of archwire: it is sufficient to mount the bending member 31, 32 whose shape is optimized for the archwire to be manufactured.

[0157] In one embodiment, the present bending device further comprises a wire cutting member 34 for cutting the wire.

[0158] In an embodiment, the wire cutting member is mounted on an articulated arm able to come in contact with the wire w at the exit 22 of the wire guiding unit 2.

[0159] In another embodiment, the wire bending members 31, 32 and the wire cutting member 34 are mounted on the same support. More preferably, they are mounted on a rotating plate 33 so that they protrude from a surface of the rotating plate 33, as shown in FIG. 11.

[0160] In one embodiment, the cutting member 34 and the wire bending members 31, 32 perpendicularly protrude from the rotating plate 33.

[0161] For efficiently cutting the wire, the cutting member 34 may be made of a material having a high hardness. For instance, it may be made of hardened steel, high speed steel (HSS) or tungsten carbide.

[0162] In one embodiment, the cutting member 34 has a flat surface 341 provided with a sharp edge for cutting the wire. In one embodiment, the cutting member is capable of rotating around the center of rotation C, and the flat surface 341 is configured to be tangential to the exit 22 when the cutting member lies on the longitudinal axis.

[0163] In one embodiment, the wire cutting member 34 is not equidistant to the two bending rods. Preferably, the wire cutting member 34 is at an angular distance larger than 90? from the first bending member 31, and at an angular distance smaller than 45? from the second bending member 32, or vice-versa. One example of this embodiment is illustrated in FIG. 11.

[0164] Having the wire cutting member 34 in proximity of one of the bending members 31, 32 allows to cut the wire right after the last bending operation. Moreover, a small rotation of the wire cutting member 34 is sufficient to cut the wire due to (i) the proximity of the cutting member 34 with one of the bending members 31, 32, combined with (ii) the presence of a flat surface 341 which is tangential to the exit 22 when the cutting member 34 lies on the longitudinal axis.

[0165] In one embodiment, the rotation of the cutting member 34 needed to cut the wire is smaller than 20?; preferably, smaller than 15?.

The System

[0166] The present invention also relates to an orthodontic wire bending system comprising: [0167] a. an orthodontic wire bending device 1 according to any one of the embodiments described hereabove, the orthodontic wire bending device 1 being responsive to control commands; [0168] b. a driver assembly comprising a first driver 213 operably connected to the wire guiding unit 2 and configured to drive the wire in the guiding unit, and a second driver 35 operably connected to the wire bending unit 3 configured to drive in rotation the at least one bending member 32, 33; and [0169] c. a programmable controller configured to send control commands to the drivers of the driver assembly, so as to operate the orthodontic bending device 1.

[0170] In one embodiment, the orthodontic wire bending system further comprises a wire detection unit for detecting the presence of the wire.

[0171] In one embodiment, the wire detection unit is installed between the wire guiding unit 2 and the wire bending unit 3. Preferably, the wire detection unit is installed between the exit 22 and the wire bending unit 3.

[0172] In one embodiment, the wire detection unit comprises a camera.

[0173] In one embodiment, the wire detection unit comprises an electrical circuit and a sensor for measuring the electrical current along said electrical circuit, so as to detect electrical current variations due to the presence or absence of the wire.

[0174] In one embodiment, the programmable controller of the orthodontic wire bending system comprises the hardware and software for controlling the drivers which drive the wire guiding unit 2 and the wire bending unit 3, i.e. the drivers 213, 35. The programmable controller may further control a driver 216 for rotating the convoying system 21.

[0175] In one embodiment, the programmable controller receives, as input, a file comprising a list of bending instructions. The programmable controller operates the bending device 1 on the basis of the bending instructions in the file.

[0176] In one embodiment, the programmable controller is configured to receive the file with the bending instructions from an external source.

[0177] In on embodiment, the orthodontic bending device comprises a human-machine interface connected to the programmable controller, and the human-machine interface comprises a display and an input device, as shown in FIG. 2.

[0178] In one embodiment, the programmable controller comprises a processor configured to execute a computer program for generating said bending instructions, and a storage medium for storing a file comprising said instructions.

[0179] The processor may be configured to receive radiological images representing the dentition of a subject, and the computer program may be configured to: [0180] generate a digital representation of the dentition of the subject, on the basis of the radiological images; [0181] receive a user input from the human-machine interface; [0182] generate a three-dimensional model of a custom orthodontic archwire, on the basis of the three-dimensional model of the subject dentition and the user input; and [0183] converting the three-dimensional model into bending instructions.

[0184] In one embodiment, the user input comprises a list of anatomical locations representing the desired position of bracket bodies.

[0185] In one embodiment, the user input comprises a list of anatomical locations representing interproximal spaces.

[0186] In one embodiment, the computer program is further configured to verify the feasibility of the bending instructions and: [0187] if the instructions can be executed by the bending device: [0188] generate a file comprising the bending instructions; [0189] send the file comprising the bending instructions to the programmable controller; [0190] if the instructions cannot be executed by the bending device: [0191] display an error message on the display of the human-machine interface.

[0192] In one embodiment, the file comprising the bending instructions is a derived form a .STL file corresponding to the desired archwire.

The Method

[0193] The present invention also relates to a method of manufacturing an orthodontic archwire with the orthodontic wire bending device 1 according to any one of the embodiments described hereinabove.

[0194] According to a first aspect, the manufacturing method comprises: [0195] guiding the wire through the wire guiding unit 2 in a first direction along the longitudinal axis, and delivering the wire out of the wire guiding unit 2 through the exit 22; [0196] feeding the wire bending unit 3 with the wire delivered from the exit 22; and [0197] rotating the wire bending member 31, 32 of a predefined angle ? around the center of rotation C so as to bend the wire.

[0198] Feeding step and rotating step may be repeated until a full orthodontic archwire is obtained.

[0199] For an orthodontic wire bending device 1 comprising one bending member 31, 32, the angle ? may be up to 360?.

[0200] For an orthodontic wire bending device 1 comprising two bending member 31, 32, the angle ? is smaller than 360?.

[0201] According to a second aspect, the method is a method for designing and manufacturing an orthodontic archwire, the method comprising: [0202] receiving radiological images representing the dentition of a subject; [0203] generating a digital representation of the subject dentition, on the basis of the radiological images; [0204] receiving a user input; [0205] generate a three-dimensional model of a custom orthodontic archwire, on the basis of the three-dimensional model of the subject dentition and the user input; [0206] converting the three-dimensional model into bending instructions; [0207] creating a file comprising the bending instructions; [0208] sending the file comprising the bending instructions to a programmable controller of the orthodontic bending device 1; and [0209] operating, by means of the programmable controller, a driver assembly comprising at least a first driver 213 operably connected to the wire guiding unit 2 and configured to drive the wire in the guiding unit, and a second driver 35 operably connected to the wire bending unit 3 and configured to drive in rotation the two bending members 32,33, on the basis of the bending instructions in the file;
wherein the steps of the method are computer-implemented.

[0210] As aforementioned, the convoying system 21 may be capable of rotating about the longitudinal axis. In this embodiment, the programmable controller may further operate a driver 216 configured to drive in rotation said convoying system 21.

[0211] The present orthodontic archwire manufacturing method allows to: [0212] a) advance the wire along a first direction parallel to the longitudinal axis; [0213] b) rotate the wire about the longitudinal axis; [0214] c) bend the wire; [0215] and to perform a), b) and c) in a succession or simultaneously.

[0216] According to a third aspect, the method of the present invention is further for cutting an archwire manufactured with the orthodontic bending device 1.

[0217] The cutting of the archwire comprises: [0218] rotating a cutting member 34 having a flat surface 341 around the center of rotation C, so as to bring the cutting member in contact with the archwire at the exit 22; [0219] further rotating the cutting member 34 such that a sharp edge of the flat surface 341 slides on the exit 22, thereby cutting the archwire.

[0220] The rotation of the cutting member 34 which allows to cut the archwire is better shown in FIG. 12.

[0221] In the embodiment of FIG. 12, the bending members 31, 32 and the cutting member 34 are mounted on the same rotating plate 33. Alternatively, each of the bending members 31, 32 and the cutting member 34 may be mounted on an independent rotating support.

[0222] In this example, a clockwise rotation of the plate 33 comprising the bending members 31, 32 provides the last bending (FIG. 12A) to the wire w. Next, a second clockwise rotation brings the cutting member 34 in contact with the wire w (FIG. 12B). As shown in FIG. 12B, the flat surface 341 of the cutting member 34 is tangential to the exit 22, and it allows to cut the wire.

[0223] As illustrated in FIG. 13, the cutting member 34 allows to cut of the wire w precisely, and without damaging it.

[0224] While various embodiments have been described and illustrated, the detailed description is not to be construed as being limited hereto. Various modifications can be made to the embodiments by those skilled in the art without departing from the true spirit and scope of the disclosure as defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0225] FIG. 1 illustrates a 50? magnification of a bent portion of a wire obtained with the orthodontic wire bending device of the prior art (FIG. 1A) and that of a wire obtained with the present orthodontic wire bending device 1 (FIG. 1B). The white arrow indicates a surface defect of the wire obtained with a device of the prior art.

[0226] FIG. 2 represents a perspective view of an exemplary orthodontic wire bending system comprising the orthodontic wire bending device 1 with a wire guiding unit 2 and a wire bending unit 3, the wire guiding unit comprising a convoying system 21, the orthodontic wire bending system further comprising: a human-machine interface including a display and a knob; a recovery box mounted in front of the bending unit 3; and a frame.

[0227] FIG. 3 is a perspective view of the wire guiding unit 2 of the present invention according to a particular embodiment in which wire guiding unit 2 comprises: [0228] a tube 214, [0229] a convoying system 21 comprising a pair of rollers 211, 212 mounted on a support 217, and a first driver 213 for driving the rollers 211, 212 in rotation, [0230] a hollow body 218, and [0231] an exit 22;
wherein the convoying system 21 can be driven in rotation about the longitudinal axis by a belt and pulley assembly 215 connected to a second driver 216, and wherein the exit 22 is a nozzle comprising a prism shaped portion and a conical portion.

[0232] FIG. 4 is a perspective view of the wire guiding unit 2 and the wire bending unit 3 according to one embodiment in which the convoying system 21 is capable of rotating about the longitudinal axis of an angle up to 180?. In FIG. 4A, said convoying system 21 is rotated of 90? (from the reference position of FIG. 3), and in FIG. 4B the rotation angle is equal to 180?.

[0233] FIG. 5A is a perspective view of the exit 22 of the wire guiding unit 2 according to one embodiment in which the exit 22 is a nozzle having a circular inner surface, said circular inner surface being rounded.

[0234] FIG. 5B is a magnified sectional view of the nozzle of FIG. 5A showing the round of the circular inner surface, said round having a constant radius of curvature r.

[0235] FIG. 6A is a perspective view of the exit 22 of the wire guiding unit 2 according to one embodiment in which the exit 22 is a nozzle comprising a cylindrical base, a prism and a cone, and in which the inner surface of the nozzle has a squared cross-section and it comprises a bevel joining said inner surface with the outer surface of the nozzle. For intelligibility purposes, a magnified sectional view of the nozzle is provided in FIG. 6B; in which the bevel of the inner surface is illustrated, said bevel having a zero radius of curvature on the other two sides (top and bottom), and a non-zero radius of curvature r.sub.L, r.sub.D on two opposite sides of the squared cross-section (left and right side), the radius of curvature of the left side r L being smaller than the radius of curvature of the right side r.sub.D.

[0236] FIG. 7 is a perspective view illustrating the bending unit 3 of the present invention according to one particular embodiment in which the two wire bending members 31, 32 are rods perpendicularly protruding from a plate 33 capable of rotating around a vertical axis z, and wherein a driver 35 is configured to drive the plate 33 in rotation.

[0237] FIG. 8 is a schematic drawing representing a top view, on the plane P, of the wire guiding unit 2 and the wire bending unit 3 of the present device according to the first configuration (FIG. 8A and FIG. 8B) or the second configuration (FIG. 8C), in which a rotation of the wire bending members 31, 32 of an angle ? around the center of rotation C results in the bending of the wire proximate to the exit 22 of an angle ?, wherein the bending angle ? depends on (i) the angle ?, (ii) the distance R between the center of rotation C and each wire bending member 32, 33 and (iii) the distance d between the center of rotation C and the exit 22.

[0238] FIG. 9 illustrates a three-dimensional archwire obtained with the present invention; the arrows indicate the interproximal spaces.

[0239] FIG. 10 is a perspective view of the wire bending unit 3 and the distal portion of the wire guiding unit 2 according to a particular embodiment in which the wire guiding unit comprises an hollow body 218 configured to deliver the wire to the exit 22, and in which the bending members 31, 32 are mounted on a rotating plate 33 and have the shape of a composite solid comprising a first cylinder, a truncated cone, and a second cylinder in a succession, so that the diameter of the bending members 31, 32 progressively decrease along the protruding direction.

[0240] FIG. 11 represents a perspective view of the wire bending unit 3 according to a particular embodiment in which the wire bending unit 3 comprises two bending members 31, 32 and a cutting member 34 for cutting the wire w delivered by the exit 22.

[0241] FIG. 12 is a top view illustrating two successive positions of the wire bending members 31, 32 and the cutting member 34 of the embodiment of FIG. 11, during a clockwise rotation of the plate 33.

[0242] FIG. 13 illustrates a 50? magnification of an extremity of an archwire cut with the cutting member 34 of FIGS. 11 and 12.