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EP-4268763-B1 - COMPUTER-IMPLEMENTED METHOD AND COMPUTING SYSTEM FOR DESIGNING AN ORTHODONTIC APPLIANCE FOR REPOSITIONING A PATIENT'S TEETH

EP4268763B1EP 4268763 B1EP4268763 B1EP 4268763B1EP-4268763-B1

Inventors

  • BORONKAY, ALLEN
  • CHENG, JIHUA
  • WU, FUMING
  • CHEN, YAN
  • MORTON, JOHN

Dates

Publication Date
20260513
Application Date
20160707

Claims (15)

  1. A computer-implemented method for designing an orthodontic appliance for repositioning a patient's teeth, the method comprising: determining (1510) a movement path to move one or more teeth from an initial arrangement to a target arrangement; determining (1520) a force system to produce movement of the one or more teeth along the movement path; determining (1530) an appliance geometry for an orthodontic appliance configured to produce the force system, wherein the orthodontic appliance comprises an outer shell (302) comprising a plurality of teeth-receiving cavities and an inner structure (304) integrally formed with an inner surface of the outer shell, the inner structure (304) comprising a stiffness different than a stiffness of the outer shell (302) such that the inner structure is configured to exhibit an amount of deformation greater than an amount of deformation exhibited by the outer shell; and generating (1540) instructions for fabricating the orthodontic appliance having the appliance geometry using an additive manufacturing technique, wherein the instructions are configured to cause a fabrication machine to form the outer shell (302) together with the inner structure (304) using the additive manufacturing technique.
  2. The computer-implemented method of claim 1, wherein the manufacturing technique is a direct fabrication technique.
  3. The computer-implemented method of claims 1 or 2, wherein the manufacturing technique is a layer-by-layer additive manufacturing technique.
  4. The computer-implemented method of any one of claims 1-3, further comprising determining a material composition for one or more of the outer shell (302) or the inner structure (304).
  5. The computer-implemented method of any one of claims 1-4, wherein the inner structure (304) includes a tooth facing surface and an outer surface of the outer shell (302) is exposed.
  6. The computer-implemented method of any one of claims 1-5, wherein the inner structure (304) and the outer shell (302) comprise different polymeric materials.
  7. The computer-implemented method of any one of claims 1-6, wherein the inner structure (304) comprises a continuous layer covering the inner surface of the outer shell (302).
  8. The computer-implemented method of any one of claims 1-6, wherein the inner structure comprises a plurality of discrete structures (502) coupled to selected portions of the inner surface of the outer shell (504).
  9. The computer-implemented method of any one of claims 1-8, wherein the inner structure (304) is configured to exhibit a first configuration prior to placement of the orthodontic appliance on the patient's teeth, and a second configuration after placement of the orthodontic appliance on the patient's teeth, and wherein the first configuration differs from the second configuration with respect to one or more of: a thickness profile of the inner structure, a cross-sectional shape of the inner structure, or an inner surface profile of the inner structure.
  10. The computer-implemented method of any one of claims 1-9, wherein an inner surface profile of the outer shell (302) differs from a surface profile of a received tooth so as to generate one or more of a force or a torque on the received tooth when the orthodontic appliance is worn on the patient's teeth.
  11. The computer-implemented method of claim 10, wherein the inner surface profile of the outer shell (302) comprises a protrusion extending toward the received tooth, and wherein the inner structure is positioned between the protrusion and the received tooth.
  12. The computer-implemented method of any one of claims 1-11, wherein the inner structure (304) is configured to produce the force system.
  13. The computer-implemented method of any one of claims 1-12, further comprising fabricating the orthodontic appliance.
  14. The computer-implemented method of any one of claims 1-13, wherein the inner structure (304) is a solid structure.
  15. A computing system comprising: a processor; and a memory comprising instructions that, when executed by the processor, cause the computing system to perform operations comprising the computer-implemented method of any one of claims 1-14.

Description

BACKGROUND Prior orthodontic procedures typically involve repositioning a patient's teeth to a desired arrangement in order to correct malocclusions and/or improve aesthetics. To achieve these objectives, orthodontic appliances such as braces, retainers, shell aligners, and the like can be applied to the patient's teeth by an orthodontic practitioner. The appliance can be configured to exert force on one or more teeth in order to effect desired tooth movements. The application of force can be periodically adjusted by the practitioner (e.g., by altering the appliance or using different types of appliances) in order to incrementally reposition the teeth to a desired arrangement. Attachments can also be placed on teeth for dental and orthodontic treatments to aid in the repositioning of a patient's teeth. The prior orthodontic methods and apparatus to move teeth can be less than ideal in at least some respects. In some instances prior orthodontic approaches that employ an appliance with homogeneous and/or continuous material properties may not provide sufficient control over the forces applied to the teeth. For example, prior appliances fabricated from a single material may exhibit less than ideal control over the forces applied to subsets of teeth. In some instances, relatively stiff orthodontic appliances may require tighter manufacturing tolerances than would be ideal, and the manufacturing tolerances may undesirably affect the accuracy of the applied forces in at least some instances. Also, in at least some instances the appliance may distort at locations away from the teeth to be moved, such that the accuracy of the tooth movement can be less than ideal. Although attachment templates have been proposed to place attachments on teeth, the prior methods and apparatus can be somewhat more difficult to use than would be ideal. Also, the accuracy of the prior attachment templates can be somewhat less accurate than would be ideal. The methods of manufacture of the prior alignment templates can be somewhat more time consuming and expensive than would be ideal. In light of the above, improved orthodontic appliances are needed. Ideally such appliances would provide more accurate tooth movement with improved control over the forces applied to the teeth, more constant amounts of force applied onto teeth during treatment, and reduced sensitivity to manufacturing tolerances. The following patent publications relate to subject-matter in the general field of the invention: US 2007/065768 (Nadav), US 2010/055635 (Kakavand), US 3,975,825 (Smith), US 2002/192617 (Phan et al.), US 2006/188834 (Hilliard) and JP 2013/123624 (Panasonic Corp). SUMMARY The present invention provides a computer-implemented method for designing an orthodontic appliance in accordance with claim 1, and a computing system according to claim 15. Optional and preferred features of the invention are defined in the dependent claims. Improved systems, methods, and devices for repositioning a patient's teeth are provided herein. An orthodontic appliance for repositioning teeth comprises heterogeneous properties in order to improve control of force and/or torque application onto different subsets of teeth. For instance, different portions of an appliance can comprise different material compositions in order to produce different localized stiffness, and the different localized stiffness can be used to generate localized forces and/or torques that are customized to the particular underlying teeth. In some embodiments, the appliance comprises a stiff outer shell that generates the force and/or torque and a compliant inner structure that engages with the tooth surface in order to improve the force and/or torque distribution to the tooth. Advantageously, the use of a compliant inner structure coupled to a stiff outer shell can reduce fluctuations in the amount of force or torque applied, which can improve the accuracy and reliability of the appliance. Alternatively or in combination, the approaches described herein for appliance design and fabrication permit the identification of spatial correspondences between portions of an appliance shell and portions of a material sheet used to form the shell, which can improve the accuracy of fabricating appliances with different localized properties for improved control of the force and/or torque application to teeth. In a first aspect, an orthodontic appliance for repositioning a patient's teeth in accordance with a treatment plan comprises an outer shell comprising a plurality of cavities shaped to receive the patient's teeth and generate one or more of a force or a torque in response to the appliance being worn on the patient's teeth. The orthodontic appliance can comprise an inner structure having a stiffness different than a stiffness of the outer shell. The inner structure can be positioned on an inner surface of the outer shell in order to distribute the one or more of a force or a torque to at least one received too