# US 2024/0197441 A1 · Techniques for determining patient teeth positions for orthodontics

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- Number: US 2024/0197441 A1
- Document ID: US20240197441A1
- Status: Published application
- Kind: A1
- Application number: 18/082,108
- Filed: 2022-12-15
- Published: 2024-06-20
- Earliest claimed: 2022-12-15
- Assignees: LightForce Orthodontics, Inc.
- Applicants: LightForce Orthodontics, Inc.
- Inventors: Alexander Yarmarkovich
- Web page: https://patentgrep.com/patent/US20240197441A1

## CPC

- A61C 7/002: {Orthodontic computer assisted systems}
- A61C 13/34: Making or working of models, e.g. preliminary castings, trial dentures; Dowel pins [4]
- G06T 19/20: Editing of three-dimensional [3D] images, e.g. changing shapes or colours, aligning objects or positioning parts
- A61C 2007/004: {Automatic construction of a set of axes for a tooth or a plurality of teeth}
- G06T 2219/2004: Aligning objects, relative positioning of parts
- A61C: DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE (non-driven toothbrushes A46B; {tongue scrapers A61B17/24;} preparations for dentistry A61K6/00; preparations for cleaning the teeth or mouth A61K8/00, A61Q11/00)
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL

## Abstract

Techniques are described for moving and aligning groups of teeth, including the teeth of an entire arch, for orthodontic treatment planning. One or more 3D models each representing one of a plurality of the patient's teeth may be analyzed to identify feature points that represent clinically relevant reference points on the tooth. An arch shape may be generated based on the feature points. One or more control points, which characterize the path of the arch shape, may then be generated (e.g., from the identified feature points). A user may provide input that modifies the positions of one or more of the control points to adjust the arrangement of teeth, thereby producing a new arch shape, and new positions of the teeth may be determined according to the new arch shape.

## Claims

### Claim 1

A computer-implemented method for determining target positions of a patient's teeth for an orthodontic procedure, the method comprising:
using at least one processor:
determining a first arch shape for initial positions of the plurality of teeth based on a plurality of feature points that each identifies a location with respect to one of the plurality of teeth;
determining a plurality of control points for characterizing the first arch shape;
receiving user input indicative of a change in position of one or more of the plurality of control points, thereby defining a modified plurality of control points;
determining a second arch shape based on the modified plurality of control points; and
determining positions of a plurality of 3D models of the patient's teeth based on the second arch shape.

### Claim 2 (depends on 1)

The method of claim 1, wherein determining the positions of the plurality of 3D models of the patient's teeth based on the second arch shape comprises determining, for each tooth of the plurality of teeth, an orientation of the tooth and a position of the tooth.

### Claim 3 (depends on 2)

The method of claim 2, wherein determining the orientation of the tooth comprises determining the orientation of the tooth for which an alignment line that passes through a centroid point of the tooth and the tooth's facial axis point is perpendicular to the second arch shape at a point where the alignment line intersects the arch shape.

### Claim 4 (depends on 2)

The method of claim 2, wherein determining the position of the tooth comprises determining the position of the tooth for which a distance between the tooth and the second arch shape matches a user selected in/out distance, wherein the in/out distance is a distance measured from the tooth's facial axis point to the second arch shape along an alignment line which passes through a centroid point of the tooth and the facial axis.

### Claim 5 (depends on 2)

The method of claim 2, further comprising determining a separation distance between a pair of adjacent teeth when the teeth are arranged according to the determined positions of the plurality of 3D models, and determining whether or not an interproximal reduction (IPR) would result between the pair of adjacent teeth based on the determined separation distance.

### Claim 6 (depends on 1)

The method of claim 1, further comprising displaying the plurality of control points via a graphical user interface.

### Claim 7 (depends on 6)

The method of claim 6, wherein the user input comprises input through the graphical user interface indicating motion of a control point from an initial position of the control point to a final position of the control point.

### Claim 8 (depends on 7)

The method of claim 7, wherein receiving the user input further comprises receiving user input indicative of bracket placement for the plurality of teeth.

### Claim 9 (depends on 6)

The method of claim 6, further comprising displaying the determined positions for the plurality of 3D models of the patient's teeth via the graphical user interface.

### Claim 10 (depends on 1)

The method of claim 1, wherein the feature points are indicative of the initial positions of the plurality of teeth.

### Claim 11 (depends on 1)

The method of claim 1, wherein determining the first arch shape comprises determining a plurality of arch points based on the plurality of feature points, and determining the first arch shape based on the determined plurality of arch points.

### Claim 12 (depends on 11)

The method of claim 11, wherein determining the plurality of arch points is based at least in part on one or more tube anchor facial axis points, canine anchor facial axis points and/or central anchor facial axis points.

### Claim 13 (depends on 12)

The method of claim 12, wherein determining the plurality of arch points comprises determining one or more of:
a distance between a pair of tube anchor facial axis points;
a distance between a pair of canine anchor facial axis points;
a distance between a pair of central anchor facial axis points;
a distance between a midpoint of the pair of central facial axis points and a midpoint of the pair of canine facial axis points; and
a distance between the midpoint of the pair of canine facial axis points and the midpoint between the pair of molar facial axis points.

### Claim 14 (depends on 11)

The method of claim 11, wherein determining the plurality of arch points comprises applying a facial distance offset to one or more of the plurality of feature points.

### Claim 15 (depends on 11)

The method of claim 11, wherein determining the first arch shape comprises generating a curve that passes through the plurality of arch points.

### Claim 16 (depends on 11)

The method of claim 11, wherein determining the plurality of control points comprises selecting the plurality of arch points as the plurality of control points.

### Claim 17 (depends on 1)

The method of claim 1, wherein determining the first arch shape comprises generating a curve that passes through the plurality of feature points.

### Claim 18 (depends on 1)

The method of claim 1, wherein determining the plurality of control points comprises determining a plurality of spline control points for the first arch shape, and selecting the plurality of spline control points as the plurality of control points.

### Claim 19 (depends on 18)

The method of claim 18, wherein determining the second arch shape comprises:
determining modified positions of the plurality of control points based on the received user input; and
upon determining the modified positions of the plurality of control points, determining an updated non-uniform rational B-spline through the final positions of the plurality of control points.

### Claim 20 (depends on 11)

The method of claim 11, wherein the second arch shape is symmetric across a sagittal plane of the patient.

### Claim 21 (depends on 11)

The method of claim 11, wherein the second arch shape is asymmetric across a sagittal plane of the patient.

### Claim 22 (depends on 1)

The method of claim 1, wherein the plurality of feature points each identify a surface location on one of the plurality of teeth.

### Claim 23 (depends on 22)

The method of claim 22, wherein the feature points comprise one or more facial axis points, marginal points, and/or centroid points.

### Claim 24

At least one computer readable medium comprising instructions that, when executed by at least one processor, perform a method for determining target positions of a patient's teeth for an orthodontic procedure, the method comprising:
determining a first arch shape for initial positions of the plurality of teeth based on a plurality of feature points that each identifies a location with respect to one of the plurality of teeth;
determining a plurality of control points for characterizing the first arch shape;
receiving user input indicative of a change in position of one or more of the plurality of control points, thereby defining a modified plurality of control points;
determining a second arch shape based on the modified plurality of control points; and
determining positions of a plurality of 3D models of the patient's teeth based on the second arch shape.

### Claim at position 25

25-46. (canceled)

### Claim 47

A system comprising:
at least one processor; and
at least one computer readable medium comprising instructions that, when executed by the at least one processor, perform a method for determining positions of a plurality of feature points of a patient's tooth based on a statistical tooth model, the method comprising:
determining a first arch shape for initial positions of the plurality of teeth based on a plurality of feature points that each identifies a location with respect to one of the plurality of teeth;
determining a plurality of control points for characterizing the first arch shape;
receiving user input indicative of a change in position of one or more of the plurality of control points, thereby defining a modified plurality of control points;
determining a second arch shape based on the modified plurality of control points; and
determining positions of a plurality of 3D models of the patient's teeth based on the second arch shape.

### Claim at position 27

48-69. (canceled)