Tooth movement measurement by automatic impression matching

• US 8,591,225 B2
• Filed: 12/12/2008
• Issued: 11/26/2013
• Est. Priority Date: 12/12/2008
• Status: Active Grant

• Current Assignee: Align Technology Incorporated
• Original Assignee: Align Technology Incorporated
• Inventors: Wu, Fuming, Matov, Vadim, Cheng, Jihua
• Primary Examiner(s): ROSEN, ERIC J
• Application Number:
  US12/334,329
• Publication Number:
  US 20100151404A1
• Time in Patent Office: 1,810 Days
• Field of Search: 433/3, 433/24, 433/213, 433/214, 328/128
• 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 computer-implemented method for the detection of deviations from an orthodontic treatment plan, comprising:

receiving a tracking model comprising a non-segmented 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 previously segmented plan model comprising a segmented digital representation of a pre-determined planned arrangement of the patient'"'"'s teeth;

performing a first alignment of the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement such that teeth in the segmented digital representation of the pre-determined planned arrangement are positioned to substantially match corresponding tooth positions in the non-segmented digital representation of the actual arrangement, the first alignment comprising;

a rough matching comprising automatically detecting a structural feature from the non-segmented digital representation of the actual arrangement previously unidentified in the tracking model and a structural feature from the segmented digital representation of the pre-determined planned arrangement, and rough aligning the non-segmented digital representation of the the actual arrangement and the segmented digital representation of the pre-determined planned arrangement based on the detected structural features; and

a fine aligning of the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement, the fine aligning comprising matching a surface of the non-segmented digital representation of the actual arrangement and a surface of the segmented digital representation of the pre-determined planned arrangement;

performing a second alignment of the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement, comprising;

comparing the non-segmented digital representation of the actual arrangement with the segmented digital representation of the pre-determined planned arrangement 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 re-aligning the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement based on the detected stationary elements; and

detecting, based on the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement as aligned per the second alignment, 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 non-segmented digital representation of the actual arrangement 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 segmented digital representation of the pre-determined planned arrangement comprises a model of the teeth in an initial arrangement, an intermediate arrangement, or a final arrangement.

5. The method of claim 1, wherein

the automatically detecting a structural feature comprises constructing a buccal ridge ellipse and an anterior middle point basis for each of the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement, and

the rough aligning comprises roughly aligning the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement by superimposing respective anterior middle point bases.

6. The method of claim 1, wherein the matching a surface of the non-segmented digital representation of the actual arrangement and a surface of the segmented digital representation of the pre-determined planned arrangement comprises using a 3-dimensional model (3D) registration algorithm to align individual teeth of the segmented digital representation of the pre-determined planned arrangement with corresponding teeth of the non-segmented digital representation of the actual arrangement.

7. The method of claim 6, wherein the 3D model registration algorithm comprises an iterative closest point algorithm.

8. The method of claim 1, further comprising assessing tooth matching quality following the fine aligning.

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

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

11. The method of claim 1, wherein said re-aligning the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement comprises optimizing a square distance of vertices in the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement, the vertices being weighted according to a probability of the vertices being stationary.

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

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

14. The method of claim 1, wherein the 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.

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

16. A computer-implemented 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; and

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

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

performing a first alignment of the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement such that teeth in the segmented digital representation of the pre-determined planned arrangement are positioned to substantially match corresponding tooth positions in the non-segmented digital representation of the actual arrangement;

performing a second alignment of the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement comprising;

comparing the non-segmented digital representation of the actual arrangement with the segmented digital representation of the pre-determined planned arrangement 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 re-aligning the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement based on the detected stationary elements; and

detecting, based on the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement as aligned per the second alignment, 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, the detecting comprising constructing a measurement reference including an occlusal plane and/or archform, and computing tooth positions in the tracking and/or plan models relative to the measurement reference.

17. The method of claim 16, wherein the initial treatment plan further comprises a prescribed timing for the tracking.

18. The method of claim 17, wherein the prescribed timing for the tracking is customized to the patient.

19. The method of claim 16, further comprising generating a revised treatment plan in response to the actual tooth arrangement deviating from the planned tooth arrangement.

20. The method of claim 19, 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 the pre-determined planned arrangement or a revised final tooth position.

21. The method of claim 20, wherein the revised treatment plan comprises a mid-course correction.

22. 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 non-segmented 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 segmented digital representation of a pre-determined planned arrangement of the patient'"'"'s teeth;

perform a first alignment of the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement such that teeth in the segmented digital representation of the pre-determined planned arrangement are aligned to substantially match corresponding tooth positions in the non-segmented digital representation of the actual arrangement, the first alignment comprising;

a rough matching comprising automatically detecting a structural feature from the non-segmented digital representation of the actual arrangement previously unidentified in the tracking model and a structural feature from the segmented digital representation of the pre-determined planned arrangement, and rough aligning the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement based on the detected structural features; and

a fine aligning of the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement comprising matching a surface of the non-segmented digital representation of the actual arrangement and a surface of the segmented digital representation of the pre-determined planned arrangement;

perform a second alignment of the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement, the second alignment comprising;

comparing the non-segmented digital representation of the actual arrangement with the segmented digital representation of the pre-determined planned arrangement 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 re-aligning the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement based on the detected stationary elements; and

detect, based on the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement as aligned per the second alignment, 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, the detecting comprising constructing a measurement reference including an occlusal plane and/or archform, and computing tooth positions in the tracking and/or plan models relative to the measurement reference.

23. 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 between the plan model and the tracking model using a partial region beyond a tooth crown of the plan model and a partial region beyond a tooth crown of the tracking model such that stationary elements of each of the plan model and the tracking model are aligned with one another, the alignment including detecting the partial region of each of the tracking model and the plan model based on a polygon formed from predetermined points on at least some of the teeth in the plan model and a polygon formed from predetermined points on at least some of the teeth 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.

24. The method of claim 23, wherein the performing an alignment further includes:

calculating an alignment transform using the detected partial regions, and

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

25. The method of claim 23, wherein the partial regions include at least one of a gingiva shape, palatine rugae and hard plate.

26. The method of claim 23, wherein the detecting the partial region of each of the tracking model and the plan model includes, for each model:

calculating a lingual cementoenamal junction (CEJ) point on each tooth in the model;

connecting the cementoenamel junction (CEJ) points in sequence to form the respective polygon;

filtering out faces which are outside of the respective polygon; and

after filtering, forming the respective partial region by combining remaining faces.

27. A computer-implemented method for the detection of deviations from an orthodontic treatment plan, comprising:

receiving a tracking model comprising a non-segmented 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 previously segmented plan model comprising a segmented digital representation of a pre-determined planned arrangement of the patient'"'"'s teeth;

performing an alignment of the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement, the alignment comprising;

a rough matching comprising automatically detecting a structural feature from the non-segmented digital representation of the actual arrangement previously unidentified in the tracking model and a structural feature from the segmented digital representation of the pre-determined planned arrangement, and rough aligning the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement based on the detected structural features; and

a fine aligning of the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement, the fine aligning comprising matching a surface of the non-segmented digital representation of the actual arrangement and a surface of the digital representation of the pre-determined planned arrangement; and

following the alignment of the non-segmented digital representation of the actual arrangement and the segmented digital representation of the pre-determined planned arrangement, 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, the detecting comprising constructing a measurement reference including an occlusal plane and/or archform, and computing tooth positions, relative to the measurement reference, in at least one of the group consisting of the tracking model and the plan model.