Defining tooth-moving appliances computationally

• US 20080182221A1
• Filed: 10/31/2007
• Published: 07/31/2008
• Est. Priority Date: 10/08/1998
• Status: Active Grant

• Current Assignee: Align Technology Incorporated
• Original Assignee: Align Technology Incorporated
• Inventors: Chishti, Muhammad, Freyburger, Brian, Pavlovskaia, Elena I., Bala, Gregory P.
• Granted Patent: US 7,874,837 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 teeth of a patient, comprising:

providing a digital model of each of a plurality of candidate shell appliances to be applied to a virtual model of the patient'"'"'s teeth;

analyzing the candidate appliances compared to the virtual model so as to compute a repositioning effect of the candidate appliances on the patient'"'"'s teeth;

generating at least partially based on the computed effect a sequence of custom appliances having teeth receiving cavities, wherein the cavities of successive appliances have different geometries selected to receive and progressively reposition the teeth, at least one appliance of the plurality comprising an added structural feature adapted to increase stiffness along at least a portion of the appliance.

3. The method of claim 2, wherein the structural feature comprises a corrugation, ridge, dimple or rim.

4. The method of claim 2, wherein the added structural feature increases appliance stiffness along a gumline portion.

5. The method of claim 2, wherein generating a custom appliance of the sequence comprises manufacturing an appliance by fitting a polymeric sheet over a positive model corresponding to a model of the patient'"'"'s teeth.

6. The method of claim 2, wherein generating a custom appliance of the sequence comprises manufacturing an appliance by stereo lithography from a digital model of the patient'"'"'s teeth.

7. The method of claim 2, wherein the virtual model is generated from a scan of the patient'"'"'s teeth or a physical model thereof.

8. The method of claim 2, wherein the computing the repositioning effect comprises performing an analysis on a digital model of the shape and material of each of the plurality of appliances to be applied to the teeth, and a structure of the patient'"'"'s teeth as set forth in the virtual model.

9. A computer-implemented method for generating shell appliances for repositioning the teeth of a patient, the method comprising:

receiving a tooth path for the motion of the tooth from an initial position toward a final position, for each tooth in a set of teeth;

defining a segmentation of the aggregate tooth paths into a plurality of treatment segments so that each tooth'"'"'s motion within a segment stays within threshold limits of motion; and

generating a plurality of successive shell appliances having teeth receiving cavities, wherein cavities of successive appliances have different geometries selected to progressively reposition the teeth from one arrangement to a successive arrangement, at least one appliance of the plurality comprising an added structural feature positioned so as to increase stiffness along at least a portion of the appliance.

10. The method of claim 9, wherein the structural feature comprises a corrugation, ridge, dimple or rim.

11. The method of claim 9, wherein the added structural feature comprises a rim positioned along a portion of the gumline so as to increases appliance stiffness along the gumline portion.

12. The method of claim 9, wherein generating a plurality of shell appliances includes:

generating a digital model of teeth;

modifying the digital model of teeth by adding or removing material;

generating a positive model from the modified digital model of teeth; and

forming a polymeric sheet using the positive model.

13. The method of claim 9, wherein the step of generating a plurality of shell appliances includes:

generating a digital model of teeth;

generating a shell appliance digital model using the digital model of teeth, the shell appliance digital model comprising a representation of the structural feature; and

fabricating a shell appliance using the shell appliance digital model.

14. The method of claim 9, wherein the step of generating a plurality of shell appliances includes:

generating a digital model of teeth;

generating a shell appliance digital model using the digital model of teeth;

performing a finite element analysis using the shell appliance digital model to compare a shell appliance with a shape substantially corresponding to the shell appliance digital model;

modifying the shell appliance digital model to add a representation of the structural feature adapted to affect the structural characteristics of the appliance; and

fabricating a shell appliance using the modified shell appliance digital model.

15. A system for use in generating shell appliances for repositioning the teeth of a patient, the system comprising:

means for receiving a tooth path for the motion of the tooth from an initial position toward a final position, for each tooth in a set of teeth;

means for defining a segmentation of the aggregate tooth paths into a plurality of treatment segments so that each tooth'"'"'s motion within a segment stays within threshold limits of motion; and

means for generating a plurality of shell appliances having teeth receiving cavities, wherein the cavities of successive appliances have different geometries selected to progressively reposition the teeth from one arrangement to a successive arrangement, wherein at least one appliance of the plurality comprises an added structural feature disposed in the appliance and positioned so as to increase stiffness along a portion of the appliance.