Patent Description:
In the production of custom-made orthodontic appliances, such as orthodontic archwires, elevated precision and accuracy are essential.

In this context, orthodontic archwire bending robots allow to produce customize archwires with higher accuracy, and more rapidly, when compared to the manual archwire shaping performed by orthodontists.

In addition to ensuring precision and accuracy, the archwire manufacturing process should not create defects on the surface of the archwire. Defects negatively affect the mechanical properties of the wire and may lead to crack formation. Once the archwire is in place, the mechanical solicitation (due to biting, chewing. ) and the acidic environment of the oral cavity may facilitate and accelerate crack propagation, thereby causing premature fracture of the archwire.

Most orthodontic archwire bending robots comprise at least one gripping tool for holding the wire to be bent in the desired shape.

In some instances, two gripping tools are provided, relatively moveable to each other, so as to hold and bend the wire at the same time.

In such systems, the friction between the fingers of the gripping tool and the wire may generate high local stress and surface defects.

Furthermore, an elevated pressure of the grippers on the wire may negatively affect the elasto-plastic properties of the wire.

In addition to the adverse effect on the wire, grippers are also associated with intrinsic limitations: over time, due to wear, the fingers of the gripping tools tend to move and to be spaced apart one from the other. Thus, the distance between the fingers and the force applied by the fingers on the wire to deviate from the nominal gripper stroke and gripping force, respectively, which ultimately leads to a loss of precision. This effect is more frequently observed at high bending angles.

Patent application <CIT> describes such a wire bending unit comprising a fixing portion with two fingers (also called jigs) for fixing the wire, and a pair of rotating bending bars for bending the wire.

Some attempts have been made to provide gripper-free orthodontic wire bending robots.

However, in most cases surface defects are still frequently observed, especially at the inside bend. <FIG> illustrates a magnification of a bent portion of a wire in which surface defects (wrinkles) have been created in the inside bend.

Patent application <CIT> describes such a gripper-free bending machine comprising a wire guide which includes a hole, and a rotatable outer portion in which the wire is bent.

The wire bending unit and the bending machine respectively described in patent applications <CIT> and <CIT> have a similar configuration: in the former, the wire leaves the fixing unit before reaching the bending bars; in the latter, the wire leaves the wire guide before reaching the rotatable outer portion. In both devices, the center of rotation of the rotating bending bars/rotatable portion is located after the place of bending of the wire in the direction of wire delivery. <CIT> discloses a method and device for shaping an orthodontic archwire. <CIT> discloses an orthodontic wire bending device.

This configuration does not provide a sufficiently precise and rapid bending of the wire.

Therefore, there is a need for a bending robot for producing orthodontic archwire in an accurate and rapid manner, and which is resistant to fatigue wear.

It is an objective of the present invention to provide an orthodontic wire bending device according to claim <NUM>, an orthodontic wire bending system according to claim <NUM> and a method of manufacturing an orthodontic archwire according to claim <NUM>.

More in particular, the present invention aims to provide orthodontic archwires without surface defects, as illustrated in <FIG>, and with an improved mechanical behavior and durability, so as to avoid the premature fracture of the archwire - fatigue wear.

It is also an objective of the present invention to provide an orthodontic archwire bending robot of compact dimensions, which can be easily manufactured and installed in an orthodontist's office.

The present invention thus relates to an orthodontic wire bending device comprising:.

wherein the exit of the wire guiding unit is located, along the first direction, beyond the center of rotation.

The present invention allows to minimize the distance between the exit of the wire guiding unit and the bending member. Thus, for a given bending moment, the force applied by the bending member to the wire is maximized, resulting in a quicker, more efficient and precise bending of the wire. This also allows more precise three-dimensional bending of the wire as the case may be.

In one embodiment, the exit is a nozzle, preferably a removable nozzle. Advantageously, this embodiment allows to employ different nozzles having different cross-sections as needed.

A rotation of the at least one bending member of an angle α results in the bending of the wire of an angle β wherein the relationship between α and β is given by the following equation: <MAT> 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.

In one embodiment, the convoying system is capable of rotating about the longitudinal axis, so as to rotate the wire about the longitudinal axis. This feature allows three-dimensional bending of the wire. Moreover, it is possible to obtain the wire translation and rotation within a single system, thereby reducing the dimensions of the orthodontic wire bending device.

In one embodiment, the wire guiding unit comprises a tube configured to house and guide the wire.

Thus, the wire may be convoyed safely until the exit.

In one embodiment, 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 which is equal or greater than the inner radius, preferably equal or greater than the inner diameter. The presence of the bevel or round avoids the creation of surface defects in the inside bend of the wire. In an embodiment, the exit may have a circular cross-section and the radius of curvature of the round may be constant.

Alternatively, the exit may have a squared cross-section with at least two different rounds having two different radii of curvature. In this alternative embodiment, it is possible to select the preferred round with a simple rotation.

In one embodiment, 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. The at least one bending member may be removable from the plate, so that different bending members may be used based on the wire characteristics and/or the archwire shape to be obtained.

In one embodiment, 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. Thus, the wire advances inside the hollow body, and it is delivered to the exit, where it is exposed to the wire bending unit and it can be bent. In one embodiment, the hollow body is made up of a metal or alloy material which ensure a smooth advancement of the wire towards the exit, and prevent the onset of rotational frictions.

In one embodiment, the at least one wire bending members is a bending rod.

In one embodiment, the bending rod has a diameter which decreases along the protruding direction, preferably the rod comprises a first part of frustoconical shape and a second free part of cylindrical shape. The decreasing diameter allows to bend the wire so as to obtain any archwire shapes, while ensuring mechanical stability of the bending member.

In one embodiment, the wire bending unit further comprises a wire cutting member, preferably the wire cutting member is a rod having a sharp edge. In this embodiment, the wire cutting function is integrated in the wire bending unit, and there is no need to provide a separate wire cutting unit.

In one embodiment, the wire bending unit comprises one bending member, preferably capable of a rotation around a center of rotation of at least180°, preferably at least <NUM>°.

According to the invention, the wire bending unit comprises one bending member capable of a translation along a direction perpendicular to the first plane.

In one embodiment, the wire bending unit comprises one bending member and the convoying system is capable of a rotation about the longitudinal axis larger than <NUM>°, preferably larger than <NUM>°, so as to provide a second order bending.

In one embodiment, the wire bending unit comprises two bending members, preferably separated by an angular distance comprised between <NUM>° and <NUM>°, more preferably between <NUM>° and <NUM>°, even more preferably, equal to <NUM>°. Within this embodiment, the convoying system may be capable of a rotation about the longitudinal axis of an angle comprised between <NUM>° and <NUM>°, so as to provide a second order bending.

The present invention also relates to an orthodontic wire bending system comprising:.

Advantageously, the controller allows to operate the different units of the orthodontic wire bending device so as to obtain the desired archwire shape.

In one embodiment, the controller is configured to receive, as input, a file comprising a list of bending instructions and to operate the orthodontic wire bending device on the basis of the bending instructions in the file. The bending instructions are obtained from a digital model of the desired archwire shape.

In one embodiment, the system further comprising a wire detection unit for detecting the presence of the wire, said wire detection unit being preferably installed between the exit of the wire guiding unit and the wire bending unit.

In on embodiment, the system comprises a human-machine interface connected to the controller. The human-machine interface may be used to visualize a three-dimensional model of a subject dentition, and to create a digital model of a customized archwire. The system may comprise a processor configured to convert the digital model of the customized archwire into bending instructions.

The present invention also relates to a method of manufacturing an orthodontic archwire with the orthodontic wire bending device according to any one of claims <NUM>-<NUM>, the method comprising:.

This method allows to efficiently and accurately bend the wire, without introducing surface defects. Thus, the archwire which is obtained is more resistant to the mechanical solicitation and the acidic environment of the oral cavity.

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.

The present invention relates to an orthodontic wire bending device <NUM> comprising a wire guiding unit <NUM>, and a wire bending unit <NUM>, as shown in <FIG>, <FIG> and <FIG>.

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 <NUM>; whereas the term "distal" refers to an element, or an element extremity, which is closer to wire bending unit <NUM>.

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

The wire bending unit <NUM> is configured to receive the wire w delivered by the exit of the wire guiding unit <NUM>. Said wire bending unit <NUM> comprises at least one wire bending member <NUM>, <NUM>, 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.

When the wire comes out of the exit <NUM>, a rotation of the at least one bending member <NUM>, <NUM> around the center of rotation C results in the bending of the wire w.

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

As illustrated in <FIG>, the wire guiding unit <NUM> comprises a convoying system <NUM> for driving the wire w, and an exit <NUM> for delivering the wire.

In the wire guiding unit <NUM> illustrated in <FIG>, the exit <NUM> is a nozzle. More in particular, the exit <NUM> 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 <NUM> is a nozzle having a proximal cylindric shape and a distal cone; mounted with a pressure screw.

The convoying system <NUM> 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.

<FIG> represents a perspective view of the wire guiding unit <NUM> of the present invention according to one particular embodiment in which the convoying system <NUM> comprises a driving roller <NUM>, a driven roller <NUM>, a driver <NUM> connected to the driving roller <NUM> and configured to drive the rollers <NUM>, <NUM> in rotation, and a tube <NUM> placed upstream of said rollers.

In some embodiments, the wire guiding unit <NUM> comprises a tube <NUM> configured to house and guide the wire; which may be installed upstream, downstream of the convoying system <NUM>, or inside the convoying system <NUM>.

In one embodiment, the convoying system <NUM> is capable of rotating about the longitudinal axis x, so as to rotate the wire w about the axis x.

One example of a rotatable convoying system <NUM> according to the present invention is illustrated in <FIG>. In this embodiment, the convoying system <NUM> is capable of rotating about the longitudinal axis x, as it can be driven in rotation by a belt and pulley assembly <NUM>, connected to a driver <NUM>. The convoying system <NUM> therein illustrated comprises a support element <NUM> on which the rollers <NUM>, <NUM> and the driver <NUM> are mounted. The support element <NUM> is connected to the belt and pulley assembly <NUM> and it has the twofold function of bearing the rollers <NUM>, <NUM> and the driver <NUM>, and permitting the rotation of the convoying system <NUM> about the axis x.

With such a rotatable convoying system <NUM> it is possible to simultaneously translate the wire along the longitudinal axis x, and rotate it about said axis.

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

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 <NUM>. With this embodiment, it is therefore possible to reduce the dimensions of the orthodontic wire bending device <NUM>.

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.

In one embodiment, the convoying system <NUM> is capable of rotating about the longitudinal axis x up to an angle of <NUM>°, preferably of at least an angle of <NUM>°, more preferably of at least an angle of <NUM>°. A rotation angle equal or greater than <NUM>° is especially interesting in a configuration with only one bending member. One example of this embodiment is illustrated in <FIG>. In <FIG>, the wire guiding unit <NUM> is represented in a first position in which the rotation angle of the convoying system <NUM> is <NUM>°, and in <FIG> it is represented in a second position in which the rotation angle is <NUM>°.

As aforementioned, the wire guiding unit <NUM> may comprise a tube <NUM> configured to house and guide the wire. Preferably, the tube <NUM> is made up of a metal or a metal alloy; more preferably, a medical grade metal or metal alloy.

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.

In one embodiment, the tube <NUM> comprises an external cover and an inner sheath.

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

In one embodiment, the inner sheath is a polymeric sheath.

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.

Preferably, the thermoplastic elastomer is a medical grade thermoplastic elastomer.

The wire guiding unit <NUM> may further comprise a hollow body <NUM> having an external surface and an internal surface defining an internal hollow portion. The hollow body <NUM> extends, along a direction parallel to the longitudinal axis x, from the convoying system <NUM> to the exit <NUM> so that the wire exiting from the convoying system <NUM>, it enters the hollow body <NUM>, it advances inside the internal hollow portion, and it is delivered to the exit <NUM> of the wire guiding unit <NUM>. Here, the wire is exposed to the wire bending unit <NUM> and it can be bent by the bending member <NUM>, <NUM>.

In one embodiment, the hollow body <NUM> is made up of a metal or alloy material.

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

In the invention, the wire guiding unit <NUM> comprise an exit <NUM> which is located, along the first direction, beyond the center of rotation C of the bending member <NUM>, <NUM>.

This set-up presents several advantages:.

In one embodiment, the exit <NUM> 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.

In one embodiment, the inner surface of the exit <NUM> has a circular or elliptical cross-section, as shown in <FIG>.

In one embodiment, the exit <NUM> has an inner surface which is beveled or rounded, i.e. filleted on an exterior corner.

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.

The exit <NUM> 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/<NUM>, 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.

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

Alternatively, the radius of curvature may be variable. For instance, the exit <NUM> of <FIG> 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>, may differ. In this particular embodiment, the radius of curvature rR of the right-side round is larger than the radius of curvature rL of the left side round.

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

In one embodiment, the inner surface of the exit <NUM> has a square or rectangular cross-section, as shown in <FIG>.

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.

In one embodiment, the exit <NUM> 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 <FIG>. In these embodiments, the exit <NUM> has a hollow frustoconical shape.

The orthodontic wire bending device <NUM> according to the present invention further comprises a wire bending unit <NUM> configured to receive the wire w delivered by the exit <NUM> of the wire guiding unit <NUM> and comprising at least one bending member <NUM>, <NUM>.

In a first configuration, the wire bending unit <NUM> comprises two bending members <NUM>, <NUM>.

One example of this embodiment is shown in <FIG>.

In a wire bending unit <NUM> comprising two bending members <NUM>, <NUM>, a rotation of the convoying system <NUM> of an angle comprised between <NUM>° and <NUM>° is sufficient to provide a second order bending. Such a small rotation of the two bending members <NUM>, <NUM> allows to render the convoying system <NUM> less complex and more stable.

In a second configuration, the wire bending unit <NUM> may comprise only one bending member <NUM>, <NUM>. One example of this embodiment is shown in <FIG>.

In a wire bending unit <NUM> comprising only one bending member <NUM>, <NUM>, the convoying system <NUM> is preferably capable of a rotation larger than <NUM>°, and more preferably larger than <NUM>°. 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.

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

The support on which the at least one bending member <NUM>, <NUM> is mounted, may be driven in rotation by a driver <NUM>, as shown in <FIG>.

In one embodiment, the support is a plate <NUM>.

In the embodiment illustrated in <FIG>, the bending members <NUM>, <NUM> are rods perpendicularly protruding from the plate <NUM>.

In one embodiment of the first configuration, the angular distance between the two bending members <NUM>, <NUM> is comprised between <NUM>° and <NUM>°. Preferably, the angular distance between the two bending members <NUM>, <NUM> is comprised between <NUM>° and <NUM>°; more preferably, it is equal to <NUM>°.

Advantageously, the combination of: (i) the angular distances between the bending members <NUM>, <NUM> and (ii) the diameter of said bending members <NUM>, <NUM>, allows to obtain an archwire which reproduces the shape of the interproximal space, indicated by the white arrows in <FIG>. 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>, the archwire obtained with the present invention is a three-dimensional archwire.

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

By providing two bending members <NUM>, <NUM> it is possible to bend the wire of large bending angles β, while reducing the angular displacements α of the bending members <NUM>, <NUM> and the number of degrees of freedom (DOFs) of the bending unit <NUM>. 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 <NUM>. Furthermore, less DOFs generate less disturbances (such as backlashes, which may negatively affect the stability of the bending unit <NUM>) and make it easier to control the bending force.

The reference position of the plate <NUM> may be defined as the position in which the two wire bending members <NUM>, <NUM> are at the same distance from the exit <NUM>.

The wire bending unit <NUM> of the second configuration comprises only one bending member <NUM>, <NUM> (for instance, only the first bending member <NUM>).

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 <NUM> may be necessary in order to bend the wire w in a direction opposite to the direction of the preceding bending.

In addition, the bending unit <NUM> may be configured to ensure the translation of the bending member <NUM> 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 <NUM> 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 <NUM> 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 <NUM> which has a higher number of degrees of freedom (DOFs). In particular, in this case the bending unit <NUM> 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 <NUM>. The reference position of the plate <NUM> may be defined as the position in which said bending member <NUM>, <NUM> faces the exit <NUM>.

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

In one embodiment, the plate <NUM> is capable of rotating about the vertical axis z of an angle up to <NUM>°.

In one embodiment, the plate <NUM> is capable of a clockwise rotation up to <NUM>° and a counterclockwise rotation up to <NUM>°, from the reference position.

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

The plane P is better shown in <FIG>, which illustrates a simplified top view of the wire guiding unit <NUM> and the wire bending unit <NUM> of the present invention on the plane P. The angles α and β, the distance R between the center of rotation C and the wire bending members <NUM>, <NUM>, and the distance d between the center of rotation C and the exit are also represented.

As shown in shown in <FIG>, when the wire w comes out of the exit <NUM>, a rotation of at least one of the bending members <NUM>, <NUM> around the center of rotation C results in the bending of the wire w.

More in particular, the wire w advances through the device in a stepwise manner from the wire guiding unit <NUM> towards the wire bending unit <NUM>, along the longitudinal axis x. After an advancement step, the wire w is bent at the wire bending unit <NUM>. Indeed, the rotation of the wire bending member <NUM>, <NUM> of an angle α results in the bending of the wire of a bending angle β, and the relationship between the angles α and β is given by equation e1: <MAT>.

By bending angle β, 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 <NUM>. 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 β of bending is defined with the angle α related to the position of the bending member at this instant. So as to reach a bending angle β for the wire, bending member has to reach an angle larger than angle α defined by equation (e1). Equation (e1) corresponds to the geometry of bend after elastic recovery.

At the next advancement step, the wire may be bent at the wire bending unit <NUM> of a second bending angle, and so on, until the desired archwire shape is obtained.

As shown in <FIG>, in the present invention, the exit <NUM> of the wire guiding unit <NUM> is located, along the first direction, beyond the center of rotation C.

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 <NUM> is positive.

Advantageously, this embodiment allows to minimize the distance between the exit <NUM> of the wire guiding unit <NUM> and the bending member <NUM>, <NUM>. Thus, for a given bending moment, the force applied by the bending member <NUM>, <NUM> to the wire w is maximized.

The presence of two bending members <NUM>, <NUM> in the first configuration allows to obtain large bending angles β with small angular displacements α of the bending members <NUM>, <NUM>. In the example illustrated in <FIG>, the bending members <NUM>, <NUM> are rotated in a counterclockwise manner to bend the wire and pass from <FIG>, so that the wire can be bent by the first bending member <NUM>. From the configuration of <FIG>, to bend the wire in the opposite direction, it is sufficient to rotate the bending members <NUM>, <NUM> in a clockwise manner, so as to bend the wire with the second bending member <NUM>.

As aforementioned, the bending member <NUM>, <NUM> 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 <NUM>, <NUM> in the plane P, which includes the longitudinal axis x, allows to reduce the dimensions of the wire bending unit <NUM>. 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.

Indeed, a coaxial bending unit would require a large distance between the center of rotation C and the bending member <NUM>, <NUM>, because the wire guiding unit <NUM> indeed would act as a physical obstacle, precluding the possibility to have the bending member proximate to the exit <NUM>.

A large distance between the center of rotation C and the bending member <NUM>, <NUM>, should be avoided because (i) the bending unit <NUM>, and hence the orthodontic wire bending device <NUM>, would occupy a large volume and (ii) the bending member <NUM>, <NUM> would require more time to reach the wire to be bent.

The rotation of the support of the bending unit <NUM>, allows to move the wire bending member <NUM>, <NUM> along a circular arc trajectory. In <FIG>, the dashed line represents a portion of the trajectory which can be covered by the bending members <NUM>, <NUM>.

The diameter of the bending member <NUM>, <NUM> is comprised between <NUM>,<NUM> and <NUM>, preferably between <NUM>,<NUM> and <NUM>.

Preferably, the diameter of the bending member <NUM>, <NUM> is at least <NUM>,<NUM>.

In one embodiment, the diameter of the bending member <NUM>, <NUM> is comprised between <NUM>,<NUM> and <NUM>. 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.

In one embodiment, the bending member <NUM>, <NUM> has a conical shape.

In one embodiment, the bending member <NUM>, <NUM> has a cylindrical shape.

In one embodiment, the bending member <NUM>, <NUM> has the shape of a composite solid. The edges shared by adjacent solids may be beveled, as illustrated for instance in <FIG>.

The decreasing diameter allows to provide a bending member <NUM>, <NUM> 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 <NUM>, <NUM>, 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.

In one embodiment, the two bending members <NUM>, <NUM> have the same shape.

In one embodiment, the two bending members <NUM>, <NUM> have different shapes.

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

In one embodiment, the bending member <NUM>, <NUM> 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.

In one embodiment, the bending member <NUM>, <NUM> 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.

Advantageously, this embodiment allows to remove and replace the bending members <NUM>, <NUM>. Different bending members <NUM>, <NUM> 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 <NUM>, <NUM>. Therefore, with this embodiment it is possible to use the same orthodontic bending device <NUM> for manufacturing a wide number of archwire: it is sufficient to mount the bending member <NUM>, <NUM> whose shape is optimized for the archwire to be manufactured.

In one embodiment, the present bending device further comprises a wire cutting member <NUM> for cutting the wire.

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 <NUM> of the wire guiding unit <NUM>.

In another embodiment, the wire bending members <NUM>, <NUM> and the wire cutting member <NUM> are mounted on the same support. More preferably, they are mounted on a rotating plate <NUM> so that they protrude from a surface of the rotating plate <NUM>, as shown in <FIG>.

In one embodiment, the cutting member <NUM> and the wire bending members <NUM>, <NUM> perpendicularly protrude from the rotating plate <NUM>.

For efficiently cutting the wire, the cutting member <NUM> 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.

In one embodiment, the cutting member <NUM> has a flat surface <NUM> 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 <NUM> is configured to be tangential to the exit <NUM> when the cutting member lies on the longitudinal axis.

In one embodiment, the wire cutting member <NUM> is not equidistant to the two bending rods. Preferably, the wire cutting member <NUM> is at an angular distance larger than <NUM>° from the first bending member <NUM>, and at an angular distance smaller than <NUM>° from the second bending member <NUM>, or vice-versa. One example of this embodiment is illustrated in <FIG>.

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

In one embodiment, the rotation of the cutting member <NUM> needed to cut the wire is smaller than <NUM>°; preferably, smaller than <NUM>°.

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

In one embodiment, the wire detection unit is installed between the wire guiding unit <NUM> and the wire bending unit <NUM>. Preferably, the wire detection unit is installed between the exit <NUM> and the wire bending unit <NUM>.

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

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.

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 <NUM> and the wire bending unit <NUM>, i.e. the drivers <NUM>, <NUM>. The programmable controller may further control a driver <NUM> for rotating the convoying system <NUM>.

In one embodiment, the programmable controller receives, as input, a file comprising a list of bending instructions. The programmable controller operates the bending device <NUM> on the basis of the bending instructions in the file.

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

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>.

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.

The processor may be configured to receive radiological images representing the dentition of a subject, and the computer program may be configured to:.

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

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

In one embodiment, the computer program is further configured to verify the feasibility of the bending instructions and:.

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

The present invention also relates to a method of manufacturing an orthodontic archwire with the orthodontic wire bending device <NUM> according to any one of the embodiments described hereinabove.

According to a first aspect, the manufacturing method comprises:.

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

For an orthodontic wire bending device <NUM> comprising one bending member <NUM>, <NUM>, the angle α may be up to <NUM>°.

For an orthodontic wire bending device <NUM> comprising two bending member <NUM>, <NUM>, the angle α is smaller than <NUM>°.

According to a second aspect, the method is a method for designing and manufacturing an orthodontic archwire, the method comprising:.

wherein the steps of the method are computer-implemented.

As aforementioned, the convoying system <NUM> may be capable of rotating about the longitudinal axis. In this embodiment, the programmable controller may further operate a driver <NUM> configured to drive in rotation said convoying system <NUM>.

The present orthodontic archwire manufacturing method allows to:.

and to perform a), b) and c) in a succession or simultaneously.

According to a third aspect, the method of the present invention is further for cutting an archwire manufactured with the orthodontic bending device <NUM>.

The rotation of the cutting member <NUM> which allows to cut the archwire is better shown in <FIG>.

In the embodiment of <FIG>, the bending members <NUM>, <NUM> and the cutting member <NUM> are mounted on the same rotating plate <NUM>. Alternatively, each of the bending members <NUM>, <NUM> and the cutting member <NUM> may be mounted on an independent rotating support.

In this example, a clockwise rotation of the plate <NUM> comprising the bending members <NUM>, <NUM> provides the last bending (<FIG>) to the wire w. Next, a second clockwise rotation brings the cutting member <NUM> in contact with the wire w (<FIG>). As shown in <FIG>, the flat surface <NUM> of the cutting member <NUM> is tangential to the exit <NUM>, and it allows to cut the wire.

As illustrated in <FIG>, the cutting member <NUM> allows to cut of the wire w precisely, and without damaging it.

Claim 1:
Orthodontic wire bending device (<NUM>) comprising:
- a wire guiding unit (<NUM>) comprising a convoying system for driving the wire (w) and an exit (<NUM>) for delivering the wire (w), the wire guiding unit being configured to guide the wire in a first direction along a longitudinal axis through the exit (<NUM>), and
- a wire bending unit (<NUM>) fed by the wire delivered by the exit (<NUM>), comprising at least one wire bending member (<NUM>, <NUM>), the at least one wire bending member (<NUM>, <NUM>) being able to turn around a center of rotation (C) in a first plane including the longitudinal axis, such that, when the wire comes out of the exit (<NUM>), a rotation of the at least one bending members (<NUM>, <NUM>) around the center of rotation (C) results in the bending of the wire (w) proximate to the exit (<NUM>),
wherein the exit (<NUM>) of the wire guiding unit (<NUM>) is located, along the first direction, beyond the center of rotation (C), and
wherein the wire bending unit (<NUM>) comprises one bending member (<NUM>, <NUM>) capable of a translation along a direction perpendicular to the first plane.