TOOTH MOVEMENT MEASUREMENT BY AUTOMATIC IMPRESSION MATCHING

• US 20100151404A1
• Filed: 12/12/2008
• Published: 06/17/2010
• Est. Priority Date: 12/12/2008
• Status: Active Grant

• Current Assignee: Align Technology Incorporated
• Original Assignee: Align Technology Incorporated
• Inventors: Matov, Vadim, Cheng, Jihua, Wu, Fuming
• Granted Patent: US 8,591,225 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 7/08 Mouthpiece-type retainers or positioners, e.g. for both the lower and upper arch arch-shaped medicament applicators for teeth or gums A61C19/063; mouthguards for protecting the teeth of sportsmen A63B71/085
• 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: A61C 9/0006 Impression trays
• CPC Class Codes: A61C 9/0053 Optical means or methods, e.g. scanning the teeth by a laser or light beam
• CPC Class Codes: G06F 18/22 Matching criteria, e.g. proximity measures
• CPC Class Codes: G06T 2207/30036 Dental; Teeth
• CPC Class Codes: G06T 7/0014 using an image reference approach
• CPC Class Codes: G06T 7/60 Analysis of geometric attributes
• CPC Class Codes: G06T 7/74 involving reference images or patches

Abstract

The present invention relates to systems and methods for detecting deviations from an orthodontic treatment plan. One method includes receiving a tracking model, performing a matching step between individual teeth in a plan model and the tracking model, comparing the tracking model with the plan model, and detecting one or more positional differences.

Claims

1. A method for automated detection of deviations from an orthodontic treatment plan, comprising:

receiving a tracking model comprising a digital representation of an actual arrangement of a patient'"'"'s teeth after an orthodontic treatment plan has begun for the patient for comparison to a plan model comprising a pre-determined planned arrangement of the patient'"'"'s teeth;

performing an automatic matching step between teeth in the plan model and the tracking model such that teeth in the plan model are repositioned to substantially match corresponding tooth positions in the tracking model;

comparing the tracking model with the plan model so as to detect stationary elements of the patient'"'"'s dentition such that positions of one or more non-stationary teeth are measurable relative to the detected stationary elements;

measuring achieved tooth movements in the tracking model; and

detecting one or more positional differences between the actual arrangement of the patient'"'"'s teeth and the pre-determined planned arrangement of the patient'"'"'s teeth.

2. The method of claim 1, wherein the tracking model is a digital representation of the actual arrangement of the patient'"'"'s teeth and is created from scanning the patient'"'"'s teeth or an impression thereof.

3. The method of claim 1, wherein the orthodontic treatment plan comprises a plurality of planned successive tooth arrangements for moving teeth along a treatment path from an initial arrangement to a selected final arrangement.

4. The method of claim 1, wherein the plan model comprises a previously segmented model of the patient'"'"'s teeth and the tracking model comprises a non-segmented raw model of the patient'"'"'s teeth and jaw in the current position.

5. The method of claim 4, wherein the previously segmented model of the patient'"'"'s teeth comprises a model of the teeth in an initial arrangement, an intermediate arrangement, or a final arrangement.

6. The method of claim 1, wherein the matching step comprises a rough alignment step followed by a fine alignment step.

7. The method of claim 6, wherein the rough alignment step comprises detecting and aligning an arch form of the tracking model and the plan model.

8. The method of claim 6, wherein the rough alignment step comprises:

constructing a buccal ridge ellipse and an anterior middle point basis for each of the planning and tracking models, and

roughly matching the plan model to the tracking model by superimposing respective anterior middle point bases.

9. The method of claim 6, wherein the fine alignment step comprises using a 3-dimensional model (3D) registration algorithm to align individual teeth of the planning model with corresponding teeth of the tracking model.

10. The method of claim 9, wherein the 3D model registration algorithm comprises an iterative closest point algorithm.

11. The method of claim 1, further comprising assessing tooth matching quality following the matching step.

12. The method of claim 1, wherein the stationary elements comprise teeth expected to remain stationary according to the treatment planning.

13. The method of claim 1, wherein the stationary elements comprise a partial region beyond a tooth crown.

14. The method of claim 1, wherein the comparing the tracking model with the plan model comprises aligning the tracking model to the plan model by optimizing a square distance of vertices in the tracking model and the planning model, the vertices being weighted according to a probability of the vertices being stationary.

15. The method of claim 1, wherein detecting one or more positional differences comprises measuring movement of a non-stationary tooth relative to a stationary element.

16. The method of claim 1, further comprising constructing archform and occlusal planes as orthodontic references for measuring movement of teeth.

17. The method of claim 1, wherein detecting one or more positional differences comprises measuring tooth movement by constructing archform and occlusal planes, constructing an archform basis for a tooth, and computing movement of the tooth relative to the corresponding archform basis.

18. The method of claim 1, wherein a detected one or more positional differences indicates that the patient'"'"'s progression through the treatment plan is substantially off track.

19. The method of claim 18, wherein the detected deviation is not substantially apparent upon visual inspection by an orthodontic professional inspecting the patient'"'"'s teeth.

20. A method of managing delivery and patient progression through an orthodontic treatment plan, comprising:

providing an initial treatment plan for a patient, the initial treatment plan comprising a plurality of planned successive tooth arrangements for moving teeth along a treatment path;

providing a plurality of orthodontic appliances for successively moving the patient'"'"'s teeth at least partially along the treatment path, the plurality of orthodontic appliances being shaped to receive the patient'"'"'s teeth;

tracking progression of the patient'"'"'s teeth along the treatment path, the tracking comprising;

receiving a tracking model comprising a digital representation of an actual arrangement of the patient'"'"'s teeth following administration of the plurality of orthodontic appliances for comparison to a plan model comprising a pre-determined planned arrangement of the patient'"'"'s teeth;

performing a matching step between individual teeth in the plan model and the tracking model such that teeth in the plan model are repositioned to substantially match corresponding tooth positions in the tracking model;

comparing the tracking model with the plan model so as to detect stationary elements of the patient'"'"'s dentition such that positions of one or more non-stationary teeth are measurable relative to the detected stationary elements; and

detecting one or more positional differences between the actual arrangement of the patient'"'"'s teeth and the pre-determined planned arrangement of the patient'"'"'s teeth.

21. The method of claim 20, wherein the initial treatment plan further comprises a prescribed timing for one or more pre-planned tracking steps.

22. The method of claim 21, wherein the prescribed timing for a pre-planned tracking step is based on a standardized protocol or customized to the patient.

23. The method of claim 20, further comprising generating a revised treatment plan where it is determined that the actual tooth arrangement substantially deviates from the planned tooth arrangement.

24. The method of claim 23, wherein the revised treatment plan comprises a plurality of successive tooth arrangements to move the patient'"'"'s teeth along a revised treatment path from their actual position directly toward a final tooth position of the pre-determined planned arrangement or a revised final tooth position.

25. The method of claim 24, wherein the revised treatment plan comprises a mid-course correction

26. A system for detecting deviations from an orthodontic treatment plan, the system comprising a computer having a processor and a computer readable medium, the computer readable medium comprising instructions that when executed cause the computer to:

receive a tracking model comprising a digital representation of an actual arrangement of a patient'"'"'s teeth after an orthodontic treatment plan has begun for the patient for comparison to a planning model comprising a pre-determined planned arrangement of the patient'"'"'s teeth;

perform a matching step between individual teeth in the plan model and the tracking model such that teeth in the planning model are aligned to substantially match corresponding tooth positions in the tracking model;

compare the tracking model with the plan model so as to detect stationary elements of the patient'"'"'s dentition such that positions of one or more non-stationary teeth are measurable relative to the detected stationary elements; and

detect one or more positional differences between the actual arrangement of the patient'"'"'s teeth and the pre-determined planned arrangement of the patient'"'"'s teeth.

27. A method for detecting deviations from an orthodontic treatment plan, comprising:

receiving a tracking model comprising a digital representation of an actual arrangement of a patient'"'"'s teeth after an orthodontic treatment plan has begun for the patient for comparison to a plan model comprising a pre-determined planned arrangement of the patient'"'"'s teeth;

performing an alignment step between the plan model and the tracking model using partial regions beyond a tooth crown of each of the plan model and the tracking model such that stationary elements of each of the plan model and the tracking model are aligned with one another; and

detecting one or more positional differences between the actual arrangement of the patient'"'"'s teeth and the pre-determined planned arrangement of the patient'"'"'s teeth.

28. The method of claim 27, wherein performing an alignment comprises:

automatically detecting the partial region of each of the tracking model and the plan model,

calculating an alignment transform using the detected partial regions, and

aligning the tracking model and the plan model using the calculated alignment transform.

29. The method of claim 27, wherein partial regions include at least one of the gingiva shape, palatine rugae and hard plate.