US-12623272-B2 - Apparatus and method for customized shaping of orthodontic archwires and other medical devices

Abstract

An apparatus and method for bending or shaping orthodontic archwires of other medical devices into a complex, patient individual shape is described. The apparatus comprises of two moveable, compact, manipulators with, in total, at least one revolute joint defining at least one rotation axes and at least one prismatic joints defining at least one translation axes; Gripping tools are provided on the manipulators.

Inventors

• Friedrich Riemeier
• Werner Butscher
• Frank Witte
• Christoph Radinger
• Andrew Cordell
• Rohit Sachdeva

Assignees

• DENTSPLY SIRONA INC.

Dates

Publication Date

20260512

Application Date

20210621

Claims (5)

1. 1 . A method of calibrating a bending apparatus comprising at least a first moveable manipulator and at least a second moveable manipulator, comprising the steps of: positioning a wire such that it is held by the first moveable manipulator and the second moveable manipulator, wherein the first moveable manipulator includes at least one revolute joint defining a first rotation axis and at least two prismatic joints defining a first translation axis and a second translation axis, and wherein the second moveable manipulator includes at least two revolute joints defining a second rotation axis and a third rotational axis; moving the first rotation axis, included as part of the first moveable manipulator, measuring movement of the first rotation axis, measuring a first resulting movement of the wire, and recording the first resulting movement; moving the first translation axis, included as part of the first moveable manipulator, measuring movement of the first translation axis, measuring a second resulting movement of the wire, and recording the second resulting movement; moving the second rotation axis, included as part of the second moveable manipulator, measuring movement of the second rotation axis, measuring a third resulting movement of the wire, and recording the third resulting movement; moving the second translation axis, included as part of the first moveable manipulator, measuring movement of the second translation axis, measuring a fourth resulting movement of the wire, and recording the fourth resulting movement; moving the third rotation axis, included as part of the second moveable manipulator, recording movement of the third rotation axis, measuring a fifth resulting movement of the wire, and recording the fifth resulting movement; developing a real model based on the recorded movements of the axes of the first moveable manipulator and the second moveable manipulator and the corresponding recorded movements of the wire; and iteratively bending and measuring single bends in the wire until correct overbending values are determined for the wire; wherein each of the axes of the first moveable manipulator and the second moveable manipulator are moved in different directions, wherein the resulting movements of the wire are measured by a vision system, and wherein measuring the resulting movements of the wire comprises using the vision system to measure the wire shape while rotating the wire about the first rotation axis to reconstruct both the actual wire cross section and actual bend formed in the wire.
2. 2 . The method of claim 1 , wherein the vision system is configured to measure the wire shape after each bend is completed, and wherein the measured wired is used to calculate grip positions for subsequent bending operations on the wire.
3. 3 . The method of claim 1 , wherein the wire is made from an alloy.
4. 4 . The method of claim 1 , wherein the wire is an orthodontic archwire.
5. 5 . The method of claim 1 , wherein developing the real model comprises: calculating joint values based on a planned bending position; calculating an actual achieved bending position; comparing the actual achieved position to the planned position; and if the difference exceeds a limit, defining a new target position by adding a compensation movement to the planned bending position.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation application claiming priority to U.S. patent application Ser. No. 16/126,930 filed Sep. 10, 2018, now issued as U.S. Pat. No. 11,072,021, which is a continuation application claiming priority to U.S. patent application Ser. No. 14/990,375 filed Jan. 7, 2016, now issued as U.S. Pat. No. 10,130,987, which is a divisional application of U.S. patent application Ser. No. 13/621,848 filed Sep. 18, 2012, now issued as U.S. Pat. No. 9,610,628, which is a continuation application of U.S. patent application Ser. No. 12/387,542 filed May 4, 2009, now issued as U.S. Pat. No. 8,266,940. BACKGROUND OF THE INVENTION A Field of the Invention This invention relates to machines and methods for automatically bending or shaping patient-specific orthodontic archwires, retainers, or other orthodontic or medical devices to a configuration having a desired geometry. B. Description of Related Art In orthodontics, a patient suffering from a malocclusion is treated by affixing brackets to the surface of the teeth and installing an archwire in the slots of the brackets. The archwire and brackets are designed to generate a customized force system that applies forces to teeth, by which individual teeth are moved relative to surrounding 20 anatomical structures into a desired occlusion. The most common approach to creating such a force system is to use off-the-shelf brackets, with or without built-in standardized prescription values, and designing a customized archwire that has complex bends designed to move or rotate the teeth in the desired direction. These complex bends are characterized by superposition of rotation along the length axis, change in angles in two planes orthogonal to the length axis, and displacements m the length axis and transverse to the wire. In general, these deformations are described by six degrees of freedom. In orthodontics, the change in angles are specified as torque, rotation and angulation. The displacements are specified according their direction relative to the teeth geometry as mesial-distal, buccal-lingual and occlusal-gingival. The wire segment to be deformed is smaller than the distance between the nearest edges of the bracket slots of the brackets bonded to two adjacent teeth and is usually in the range of only a few millimeters. Machines for bending orthodontic archwires have been proposed in the prior art. Andreiko et al., in U.S. Pat. No. 5,447,432, describes an apparatus that takes a straight archwire and imparts a simple planar arcuate curvature to the wire. The wire is customized in the sense that the shape of the arc is designed for a particular patient, but the wire bending apparatus described in Andreiko et al. is limited to a customized bracket approach to orthodontics. In particular, the Andreiko et al. wire bending apparatus cannot produce any complex bends in the wire, e.g., bends requiring a combination of translation and rotational motion. The required force system is created by virtue of the design of customized brackets, and in particular slot positions and orientations in the brackets and their exact placement on the teeth in desired positions, such that the brackets interact with the flat planar wire to move teeth into desired positions. The patent to Orthuber et al., U.S. Pat. No. 4,656,860, describes a bending robot for bending archwires. A robot as described in the '860 patent was developed by the predecessor of the assignee of the present invention and used experimentally for several years, but never widely commercialized. The robot consisted of two characteristic design features: a bending cone that could move forwards and backwards to bend the wire, and a rotating cone that could twist the wire. Accordingly, this machine could perform, within a single bending step, only a deformation around a main axis of the wire. To do a complex deformation of the archwires with six degrees of freedom as commonly required for orthodontic patient-specific archwires, the machine of the '860 patent would typically require a sequence of five single bending steps, comprising three torque (twisting) steps and two bending steps. The archwire segment length necessary to accomplish these plurality of steps usually exceeds the available distance between the nearest edges of the two adjoining bracket slots. Hence, the '860 patent would not work for many orthodontic prescriptions. Additionally, the '860 bending machine was rather imprecise because the robot has no effective feedback mechanism for detecting how the wire in fact was bent after a particular bending or twisting operation was performed. Furthermore, manufacturing inaccuracies of each bending step lead to a relative large error in the whole deformation between two adjacent bracket slots. The deficiencies in the '860 patent led the present assignee to develop an improved wire bending machine, described in the patents of Wemer Butscher, et al., see U.S. Pat. Nos. 6,612