Defining tooth-moving appliances computationally

• US 20050079468A1
• Filed: 08/30/2004
• Published: 04/14/2005
• Est. Priority Date: 10/08/1998
• Status: Active Grant

• Current Assignee: Align Technology Incorporated
• Original Assignee: Align Technology Incorporated
• Inventors: Freyburger, Brian, Chishti, Muhammad, Pavlovskaia, Elena I., Bala, Gregory P.
• Granted Patent: US 7,320,592 B2
• Time in Patent Office: Days
• US Class Current: 433/24
• CPC Class Codes: A61C 7/00 Orthodontics, i.e. obtaining or maintaining the desired position of teeth, e.g. by straightening, evening, regulating, separating, or by correcting malocclusions
• CPC Class Codes: A61C 7/002 Orthodontic computer assisted systems
• CPC Class Codes: A61C 9/00 Impression cups, i.e. impression trays; Impression methods computer-assisted sizing A61C13/0004; instruments for determining occlusion A61C19/05
• CPC Class Codes: B33Y 80/00 Products made by additive manufacturing

Abstract

Methods and corresponding apparatus for segmenting an orthodontic treatment path into clinically appropriate substeps for repositioning the teeth of a patient include providing a digital finite element model of the shape and material of each of a sequence of appliances to be applied to a patient; providing a digital finite element model of the teeth and related mouth tissue of the patient; computing the actual effect of the appliances on the teeth by analyzing the finite elements models computationally; and evaluating the effect against clinical constraints. The appliances can be braces, polymeric shells, or other forms of orthodontic appliance.

Claims

1. (canceled).

2. A computer-implemented method for designing custom appliances for repositioning the teeth of a patient, comprising:

scanning a patient'"'"'s teeth or a physical model thereof to generate a virtual model;

computing the actual effect of the appliances on the teeth by performing structural analysis on the virtual model; and

generating a sequence of custom appliances having geometries selected to progressively reposition the teeth.

5. The method of any one of claims 2 to 4, wherein the sequence of appliances includes a sequence of configurations of braces, the braces including brackets and archwires.

6. The method of any one of claims 2 to 4, wherein the sequence of appliances includes a sequence of polymeric shells manufactured by fitting polymeric sheets over positive models corresponding to the teeth of the patient.

7. The method of any one of claims 2 to 4, wherein the sequence of appliances includes a sequence of polymeric shells manufactured by stereo lithography from digital models.

8. The method of any one of claims 2 to 4, further comprising:

comparing the actual effect of the appliances with an intended effect of the appliances; and

identifying an appliance as an unsatisfactory appliance if the actual effect of the appliance is more than a threshold different from the intended effect of the appliance and modifying a model of the unsatisfactory appliance according to the results of the comparison.

9. The method of claim 8, wherein the model of the unsatisfactory appliance is modified by modifying the shape of the unsatisfactory appliance.

10. The method of claim 9, wherein the shape of the unsatisfactory appliance is modified by adding a dimple.

11. The method of claim 9, wherein the shape of the unsatisfactory appliance is modified by adding material to cause an overcorrection of tooth position.

12. The method of claim 9, wherein the shape of the unsatisfactory appliance is modified by adding a ridge of material to increase stiffness.

13. The method of claim 9, wherein the shape of the unsatisfactory appliance is modified by adding a rim of material along a gumline to increase stiffness.

14. The method of claim 9, wherein the shape of the unsatisfactory appliance is modified by removing material to reduce stiffness.

15. The method of claim 8, wherein the unsatisfactory appliance is redefined to have a shape defined by the complement of the difference between the intended effect and the actual effect of the unsatisfactory appliance.

20. The method of any of claims 2 to 4, wherein the last of the sequence of appliances is a positioner for finishing and maintaining teeth positions.

3. A computer-implemented method for designing custom appliances for repositioning the teeth of a patient, comprising:

scanning a patient'"'"'s teeth or a physical model thereof to generate a virtual model;

computing the actual effect of the appliances on the teeth by performing finite element analysis on said virtual model; and

generating a sequence of custom appliances having geometries selected to progressively reposition the teeth.

4. A computer-implemented method for generating one or more appliances for repositioning the teeth of a patient, comprising:

scanning a patient'"'"'s teeth or a physical model thereof;

providing a digital model of the shape and material of each of a sequence of appliances to be applied to the teeth;

providing a digital model of the teeth and related mouth tissue of the patient using data obtained by said scanning;

computing the actual effect of the appliances on the teeth by performing finite element analysis on said models;

evaluating the effect against clinical constraints; and

generating a sequence of appliances having geometries selected to progressively reposition the teeth.

16. The method of claim 4, wherein the clinical constraint is selected from the group consisting of a maximum rate of displacement of a tooth, a maximum force on a tooth, and a desired end position of a tooth.

17. The method of claim 16, wherein the clinical constraint comprises a maximum rate of linear displacement of a tooth.

18. The method of claim 16, wherein the clinical constraint comprises a maximum rate of rotational displacement of a tooth.

19. The method of claim 16, wherein the clinical constraint comprises a linear force or a maximum torsional force.

21. A computer program product, tangibly stored on a computer-readable medium, comprising instructions operable to cause a computer to:

provide a digital model of the shape and material of each of a sequence of appliances to be applied to the teeth of the patient;

provide a digital model of the teeth and related mouth tissue of the patient using data obtained by scanning the patient'"'"'s teeth;

compute the actual effect of the appliances on the teeth by performing finite element analysis on said models;

evaluate the effect against clinical constraints; and

generate a plurality of appliances having geometries selected to progressively reposition the teeth, wherein the appliances comprise polymeric shells having cavities and wherein the cavities of successive shells have different geometries shaped to receive and resiliently reposition teeth from one arrangement to a successive arrangement.

22. The product of claim 21, wherein the sequence of appliances includes a sequence of configurations of braces, the braces including brackets and archwires.

23. The product of claim 21, wherein the sequence of appliances includes a sequence of polymeric shells manufactured by fitting polymeric sheets over positive models corresponding to the teeth of the patient.

24. The product of claim 21, wherein the sequence of appliances includes a sequence of polymeric shells manufactured by stereo lithography from digital models.

25. The product of claim 24, further comprising instructions to:

compare the actual effect of the appliances with an intended effect of the appliances; and

identify an appliance as an unsatisfactory appliance if the actual effect of the appliance is more than a threshold different from the intended effect of the appliance and modify a model of the unsatisfactory appliance according to the results of the comparison.

26. The product of claim 25, wherein the model of the unsatisfactory appliance is modified by modifying the shape of the unsatisfactory appliance.

27. The product of claim 26, wherein the shape of the unsatisfactory appliance is modified by adding a dimple.

28. The product of claim 26, wherein the shape of the unsatisfactory appliance is modified by adding material to cause an overcorrection of tooth position.

29. The product of claim 26, wherein the shape of the unsatisfactory appliance is modified by adding a ridge of material to increase stiffness.

30. The product of claim 26, wherein the shape of the unsatisfactory appliance is modified by adding a rim of material along a gumline to increase stiffness.

31. The product of claim 26, wherein the shape of the unsatisfactory appliance is modified by removing material to reduce stiffness.

32. The product of claim 25, wherein the model of the unsatisfactory appliance is redefined to have a shape defined by the complement of the difference between the intended effect and the actual effect of the unsatisfactory appliance.

33. The product of claim 21, wherein the clinical constraints include a maximum rate of displacement of a tooth, a maximum force on a tooth, and a desired end position of a tooth.

34. The product of claim 33, wherein the maximum force is a linear force or a torsional force.

35. The product of claim 33, wherein the maximum rate of displacement is a linear or a angular rate of displacement.

36. The product of claim 21, wherein the clinical constraints include a maximum rate of displacement of a tooth.

37. The product of claim 21, wherein the clinical constraints include a maximum rate of linear displacement of a tooth.

38. The product of claim 21, wherein the clinical constraints include a maximum rate of rotational displacement of a tooth.

39. A system for segmenting an orthodontic treatment path into clinically appropriate substeps for repositioning the teeth of a patient, comprising:

means for scanning a patient'"'"'s teeth or a physical model thereof;

means for providing a digital model of the shape and material of each of a sequence of appliances to be applied to the patient;

means for providing a digital model of the teeth and related mouth tissue of the patient to use data obtained by said scanning means;

means for computing the actual effect of the appliances on the teeth by performing finite element analysis on said models;

means for evaluating the effect against clinical constraints; and

means for generating a plurality of appliances having geometries selected to progressively reposition the teeth, wherein the appliances comprise polymeric shells having cavities and wherein the cavities of successive shells have different geometries shaped to receive and resiliently reposition teeth from one arrangement to a successive arrangement.

40. The system of claim 39, further comprising:

means for comparing the actual effect of the appliances with an intended effect of the appliances; and

means for identifying an appliance as an unsatisfactory appliance if the actual effect of the appliance is more than a threshold different from the intended effect of the appliance and modifying a model of the unsatisfactory appliance according to the results of the comparison.