CN108056829B

CN108056829B - Method for facilitating dental treatment with repositioning of teeth

Info

Publication number: CN108056829B
Application number: CN201710978944.XA
Authority: CN
Inventors: 高飞
Original assignee: Guidemia Technologies Shanghai Co ltd
Current assignee: Guidemia Technologies Shanghai Co ltd
Priority date: 2017-10-19
Filing date: 2017-10-19
Publication date: 2021-04-16
Anticipated expiration: 2037-10-19
Also published as: CN108056829A

Abstract

A method for facilitating tooth repositioning dental treatment comprising: receiving a CT scan of a dental structure in the patient's mouth, receiving an optical scan of the dental structure in the patient's mouth, registering the CT scan and the optical scan, building an initial model of the dental structure in the patient's mouth based on the CT scan and the optical scan, simulating tooth movement, generating a final model of the dental structure in the patient's mouth that is ideal after treatment, generating a plurality of intermediate models of the dental structure in the patient's mouth that represent successive tooth movements from the initial model to the final model, and preparing a dental appliance based on the plurality of models of the dental structure in the patient's mouth.

Description

Method for facilitating dental treatment with repositioning of teeth

Technical Field

The present invention relates generally to the field of orthodontics. More particularly, the present invention relates to a method for facilitating dental repositioning dental treatment.

Background

Repositioning of teeth is routinely accomplished by physicians by wearing "orthodontic brackets". Orthodontic bracket attachment to a patient's teeth is a cumbersome and time consuming task. Therefore, conventional orthodontic treatment is inconvenient. The doctor also accomplishes repositioning of the teeth by wearing "appliances" on the patient. A set of appliances are installed in stages on the patient's teeth to gradually reposition the teeth from an initial tooth arrangement, through several intermediate tooth arrangements, to a final tooth arrangement.

The appliances are essentially a series of shell models designed based on crown data and inferred from tooth positions. The oral dental structure has four parts: the crown, the root, the soft tissue and the occlusal relationship of the lower jaw and the upper jaw. Appliances are designed based solely on crown data and therefore do not fully represent the patient's anatomy, often with mismatches from the actual intermediate tooth arrangement during treatment. As a result, the orthotic often needs to be redesigned and reworked to complete the repositioning process.

There is a need for a method of designing a tooth repositioning device in which the appliance is designed based on the crown, root, soft tissues and joints of the lower and upper jaws and which properly represents the patient's anatomy.

Disclosure of Invention

A method for facilitating tooth repositioning dental treatment comprising: receiving a CT scan of a patient oral dental structure, receiving an optical scan of a patient oral dental structure, registering the CT scan and the optical scan, building an initial model of the patient oral dental structure based on the CT scan and the optical scan, simulating tooth movement to produce a final model of the patient oral dental structure after a desired treatment, generating a plurality of intermediate models of the patient oral dental structure representing successive tooth movements from the initial model to the final model, and preparing a dental appliance based on the plurality of models of the patient oral dental structure.

The method further includes segmenting the tooth data of the CT scan to obtain a segmented CT scan, the segmented CT scan including crown data and root data.

The method further includes segmenting the crown data of the optical scan to obtain a segmented optical scan, the segmented optical scan including soft tissue data.

In the method, the establishing an initial model of the dental structure of the patient's oral cavity is based on the segmented CT scan and the segmented optical scan.

In the method, the CT scan of the patient's oral dental structure is a CT scan of the patient's oral dental structure at a first jaw-opening angle, the optical scan of the patient's oral dental structure is an optical scan of the patient's oral dental structure at a second jaw-opening angle, and a difference between the first jaw-opening angle and the second jaw-opening angle is 1 degree or greater.

The method also includes creating a virtual joint based on the CT scan, the optical scan, or both, the simulated tooth movement being based on the virtual joint and an adjustment of individual tooth movement.

The method also includes generating an axis of a temporomandibular joint of a dental structure of the patient's oral cavity from the CT scan, the optical scan, or both, and applying the axis when creating the virtual joint.

The method further includes segmenting the tooth data of the CT scan to obtain a segmented CT scan, segmenting the crown data of the optical scan to obtain a segmented optical scan, and creating a virtual joint based on the segmented CT scan and the segmented optical scan; the segmented CT scan includes crown data and root data, the segmented optical scan includes soft tissue data; the establishing the initial model of the dental structure of the patient's oral cavity is based on the segmented CT scan, the segmented optical scan, or both, the simulated tooth movement is based on the virtual joints and adjustments of individual tooth movements.

In the method, the CT scan and the optical scan data are both displayed in a 3D image and a 2D image, the 3D image and the 2D image include jaw bone region data surrounding the tooth, and the tooth repositioning dental treatment is evaluated against the jaw bone region data surrounding the tooth.

In the method, a plurality of teeth may be moved as a single entity in the tooth repositioning dental treatment.

A method for facilitating tooth repositioning dental treatment comprising: receiving a scan of a patient's oral dental structure at a first jaw opening angle, receiving a scan of a patient's oral dental structure at a second jaw opening angle, registering the scan of the first jaw opening angle and the scan of the second jaw opening angle, building an initial model of a patient's oral dental structure based on the scan of the first jaw opening angle and the scan of the second jaw opening angle, simulating tooth movement to produce a final model of the patient's oral dental structure after a desired treatment, generating a plurality of intermediate models of a patient's oral dental structure representing successive tooth movements from the initial model to the final model, and preparing a dental appliance based on the plurality of intermediate models of the patient's oral dental structure, wherein a difference between the first jaw opening angle and the second jaw opening angle is greater than 1 degree.

The method further includes segmenting the tooth data of the first open jaw angle scan to obtain a first open jaw angle segmentation scan, and segmenting the crown data of the second open jaw angle scan to obtain a second open jaw angle segmentation scan.

In this method, the establishing the initial model of the dental structure of the patient's oral cavity is based on a segmentation scan of the first jaw opening angle, a segmentation scan of the second jaw opening angle, or both.

The method also includes creating a virtual joint based on the scan of the first opening angle, the scan of the second opening angle, or both, simulating tooth movement based on the virtual joint and adjustment of individual tooth movement.

The method further comprises the following steps: generating an axis of a temporomandibular joint of a dental structure of the patient's oral cavity from the scan of the first jaw angle, the scan of the second jaw angle, or both, and applying the axis when creating the virtual joint.

The method also includes segmenting the tooth data of the first open jaw angle scan to obtain a segmentation scan of a first open jaw angle, segmenting the crown data of the second open jaw angle scan to obtain a segmentation scan of a second open jaw angle, and creating a virtual joint based on the segmentation scan of the first open jaw angle, the segmentation scan of the second open jaw angle, or both. The establishing the initial model of the dental structure of the patient's oral cavity is based on a segmentation scan of the first jaw opening angle, a segmentation scan of the second jaw opening angle, or both, the simulating movement of the teeth is based on the virtual joints.

In the method, the scan of the dental structure of the patient's oral cavity is a CT scan or an optical scan.

A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of any of the methods described above.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

In the drawings:

FIG. 1a is a CT scan showing a patient in a 2D cross-sectional mode;

FIG. 1b is a CT scan showing a patient in 3D mode;

FIG. 2 is a diagram showing dental structures in a patient's mouth at an open jaw angle;

FIG. 3 is a view showing a dental structure of a patient's mouth in a closed position;

FIG. 4 is a dental model showing dental structures in a patient's mouth;

FIG. 5 is a diagram showing registration of a CT scan and an optical scan using ICP, with three points on each image representing fiducial points for matching the two scans;

FIG. 6 is an optical scan showing registration with a CT scan;

FIG. 7 is a diagram showing two different jaw opening angles generated by a virtual joint based on CT scans and optical scans with different jaw opening angles;

FIG. 8 is an axis of a temporomandibular joint showing dental structures in a patient's mouth;

FIG. 9 is a graph showing segmentation of a tooth structure by thresholding so that the operator can select only high density regions;

FIG. 10 is a graph showing segmentation of a tooth structure by thresholding so that the operator can better select regions of the teeth and further select teeth of interest with the software tool;

FIG. 11 is a diagram showing the resulting tooth model;

FIG. 12 is a diagram illustrating the definition of a boundary for a tooth of interest, where the boundary is at the junction between the soft tissue and the crown;

FIG. 13 is a diagram illustrating the definition of a boundary for a tooth of interest, including a crown and surrounding tissue;

FIG. 14 is a graph showing that teeth have been fully segmented from a model;

FIG. 15 is a view showing a moving tooth; on the left side, the tooth, i.e. its crown and root, is moved with the positioning tool; on the right, the crown is moved, the tissue is deformed;

FIG. 16 is a function showing a displacement for defining a point on a tissue region relative to a distance between the point and a tooth boundary;

FIG. 17 is a view showing movement of teeth in CT tomographic imaging;

FIG. 18 is a view showing an attachment designed to assist in moving teeth;

figure 19a shows the shell model, appliance and teeth under the appliance; in fig. 19a, the shell model or appliance is shown in phantom lines and the teeth under the appliance are shown in solid lines; the deflection of the surface will generate a force that moves the teeth as indicated by the arrows; FIG. 19b is a diagram showing an original tooth model, a tooth model with local deformation, an appliance made from the deformation model applied to the actual teeth, and raised areas that generate additional force to move the teeth;

figure 20 is a combination illustrating the geometry of the appliance not precisely matching teeth.

Detailed Description

Reference will now be made in detail to implementations of the present invention, examples of which are illustrated in the accompanying drawings.

The present invention provides a method for facilitating dental treatment of teeth repositioning. The method comprises the following steps: receiving a CT scan of a dental structure of a patient's oral cavity, receiving an optical scan of the dental structure of the patient's oral cavity, registering the CT scan and the optical scan, building an initial model of the dental structure of the patient's oral cavity based on the CT scan and the optical scan, simulating tooth movement to produce a final model of the dental structure of the patient's oral cavity after a desired dental treatment, generating a plurality of intermediate models of the dental structure of the patient's oral cavity representing successive tooth movements from the initial model to the final model, and preparing a dental appliance based on the plurality of intermediate models of the dental structure of the patient's oral cavity.

CT scans, also known as X-ray computed tomography or computerized axial tomography scans, utilize a computer-processed combination of multiple X-ray images taken from different angles to produce a cross-sectional (tomographic) image (virtual "slice") of a particular region of the scanned object. Here, the scan object is a dental structure of the oral cavity of the patient.

First, a CT scan is obtained for the patient. The data of the CT scan is observed in a computer system and a 3D reconstruction is performed to display the CT tomographic data in a 3D space, fig. 1a being a 2D CT scan of a patient and fig. 1b being a 3D CT scan of the patient.

When the CT scan of both the upper and lower jaw is obtained in one scan, the patient's two jaws may have different positions: the upper and lower jaws are separated by a soft and lightweight material, such as a cotton pad, to obtain a split jaw position, or the jaws are in a closed position. To describe the patient's jaw position, the term jaw opening angle is used. The jaw opening angle is defined as the angle formed by a plane representing the patient's upper jaw and a plane representing the patient's lower jaw. When the jaw is fully closed, this angle is considered to be 0.

FIG. 2 is a dental structure of a patient's oral cavity showing an open jaw angle a, which can be 0-50 degrees. When the jaw opening angle (a) is 0 degrees (the plane representing the patient's upper jaw is parallel to the plane representing the patient's lower jaw), the patient's oral dental structures are in the closed position. Fig. 3 is a diagram illustrating a dental structure of a patient's mouth in a closed position.

When the patient's jaw has an open jaw angle (a), a CT scan is obtained. The jaw opening angle (a) may be 0-50 degrees. For example, a CT scan is obtained when the jaw opening angle of the patient's jaw is 0 degrees, 1 degree, 5 degrees, 8 degrees, or 10 degrees.

Next, an optical scan of the dental structure of the patient's oral cavity is obtained. An intraoral scanner may be used which acquires data directly by scanning the patient's teeth and gums. It is also possible to make a dental model of the dental structure of the patient's mouth and then scan the model using any optical scanner to obtain a digital model of the teeth and gums.

Similar to CT scanning, an optical scan is obtained. Fig. 4 is a dental model showing dental structures in a patient's mouth. When the patient's jaw has an open jaw angle (a). The jaw opening angle (a) may be 0-50 degrees. For example, the optical scan is obtained when the jaw angle of the patient's jaw is 0 degrees, 1 degree, 5 degrees, 8 degrees, or 10 degrees.

A better option is to obtain an optical scan when the jaw opening angle (a) of the patient's jaw differs from the jaw opening angle of the CT scan. Specifically, a CT scan is obtained when the patient's jaw has a first jaw opening angle, and an optical scan is obtained when the patient's jaw has a second jaw opening angle. The difference between the first and second jaw opening angles is 1 degree or more, 5 degrees or more, 8 degrees or more, or 10 degrees or more. For example, the first jaw opening angle is 0 degrees and the second jaw opening angle is 1, 5, 8, or 10 degrees.

The optical scan may be one single digital file with two jaws, or one digital file per jaw. If the two jaws are placed in a single file, computer methods can be used so that at a later stage they can be separated into two separate parts; in the rest of the invention, the optical scanning will be as two models or two documents, one for each jaw. However, this is not necessary to practice the invention.

In the next step, the computer system will have a module to load and align both the CT data and the optical scan data together.

The computer system will employ a registration method based on point or patch matching of the two jaws. Taking the upper jaw as an example, the system will display both the CT data and the upper jaw model. The user may use automated methods or manual tools to specify locations (points or regions) in the CT data that correspond to the locations of the optical scans.

Algorithms such as "iterative closest point" (ICP) can be used to match the specified regions, so a transformation will be created to move the optical data of the jaw to the location of the CT data. Fig. 6 is a diagram illustrating registration of a CT scan and an optical scan using ICP.

When a CT scan is obtained when a patient's jaw has a first jaw opening angle, an optical scan is obtained when the patient's jaw has a second jaw opening angle, and a difference between the first jaw opening angle and the second jaw opening angle is 1 degree or more, 5 degrees or more, 8 degrees or more, or 10 degrees or more, data sets of two jaw positions are acquired. This creates a virtual joint of the two jaws. Software tools can be used to push in or extrapolate the position of the joints, which can then simulate the opening and closing of the jaw. Fig. 7 is a diagram showing a virtual joint based on CT scanning and optical scanning with different jaw opening angles.

This virtual joint cannot be established when both CT and optical scans are obtained at the same jaw opening angle. In this case, the temporomandibular joint is used to define the joint of the jaw. The virtual axis may be specified by looking at the CT scan and identifying the joint.

The movements of the mandible are very complex but can be simplified to rotations around the temporomandibular joint. By means of CT scanning and/or optical scanning, the axes of the temporomandibular joints of dental structures in the patient's mouth can be established. The axes may then be applied to create a virtual joint. Fig. 8 is an axis of a temporomandibular joint showing dental structures in a patient's mouth.

In the next step, the CT scan is processed to isolate the root. An image processing procedure is used to correlate the 3D model with the imaging of the 2D slice. The segmentation tool is used to create individual root models from the CT dataset on which the regions corresponding to the teeth of interest are created. And the tool is used to separate the individual teeth, at least part of the crown, from the CT data.

Two image windows are displayed in the computer system. The system is equipped with a thresholding tool that can alter the thresholding of the 2D view and update the 3D imaging accordingly. For individual teeth, the user can adjust the threshold so that the root data is filtered appropriately. Pixels of a tooth or group of teeth are captured from the CT data using a segmentation or cutting tool. The 3D pixels for the dental data are converted into a 3D surface model represented by geometric data such as faces and points.

Fig. 9 is a diagram illustrating segmentation of a tooth structure by thresholding such that only high density regions are selected.

Fig. 10 is a graph showing the segmentation of a tooth structure by thresholding, such that a good region of the tooth is selected and the tool is used to further select the tooth of interest.

Fig. 11 is a view showing the resulting tooth model.

Depending on the current tooth arrangement or orthodontic treatment needs, the user may create models for individual roots or for multiple roots in one operation. A plurality of operations are performed to obtain the entire dental structure of the patient. It may be necessary to apply the same operation to the upper and lower jaws of a patient of the same CT data set or different data sets.

Next, the optical data of the jaw will be processed so that crown and soft tissue models can be obtained. Similar to the method of CT data segmentation, crowns may be separated individually or in groups. For example, the user would specify only points around two crown boundaries, and the system would treat the connection points as a ring, and select the area within the ring as the crown model for the lower tooth/teeth.

It is not necessary to completely separate the crown from the boundary between the crown and the soft tissue. The separation of the crown from the optical data may include segmenting the crown region only or segmenting the crown region and some surrounding soft tissue. This is done for two reasons: 1) the model or optical scan may not produce a clear boundary of the crown; 2) the user determines that it is helpful to move some of the surrounding tissue with the crown. This will also be addressed in the tissue deformation step.

Fig. 12 is a diagram illustrating the definition of a boundary for a tooth of interest, where the boundary is at the junction between the soft tissue and the crown.

FIG. 13 is a diagram illustrating the definition of a boundary for a tooth of interest, including a crown and surrounding tissue.

After segmenting all of the crown models of the optical scan, the remaining regions on the digital model are considered soft tissue.

At this point in time, a complete model of the oral dental structure with roots, jaws, crowns, soft tissues and joints has been established. The second stage of the method is to simulate tooth movement. The user will determine the amount and manner of movement of the teeth through various criteria, such as aesthetics of tooth arrangement, occlusion of the jaw, surrounding bone structure and bone density, and the available basis for the joint.

The joint positions of the jaws can be used to move the jaws in their entirety in order to determine an optimal target position for the entire jaw. The user can adjust the joint angle. Individual teeth or groups of teeth are then repositioned to simulate treatment results. A visualization tool will be provided to the user to understand how the teeth move.

Each of the teeth or groups of teeth may be displayed as a combination of a tooth root and a crown, or a combination of CT data and optical data. Thus, as the tooth moves, the system will show how the root moves accordingly. The movement can be displayed in CT slices and 3D space. In CT tomography, the user can assess the bone density of the area around the tooth and determine that movement is easy or difficult. In the 3D space, any possible collision of the crown and the root can be seen. Feedback tools are used to alert the user whether the movement will cause a collision.

FIG. 14 is a diagram showing teeth that have been segmented from a model and shown in different colors.

When simulating tooth movement, the point/surface patches of the tissue model with the corresponding number of teeth are changed. As the teeth move, the surrounding tissue area deforms to follow the movement. Points close to the tooth boundary will move with the boundary and areas further from the boundary will move a smaller distance. This approach will ensure that the deformation of the soft tissue generally follows the tooth movement.

Soft tissue deformation is an automated process. For each point on the tooth boundary, there will be a vertex of the adjacent region or mesh. This is used to represent the surface model. Together, these points constitute a candidate set of deformations. When a tooth is moved, all of these points will be reclassified as "to-be-moved" and "not to-be-moved" relative to the tooth. Furthermore, the distance between the point and the tooth boundary will be used to calculate how the point will move. For example, a Gaussian distribution model is used to ensure that the displacement of the "to-be-moved" point will be between 0 and the closest point on the tooth boundary, and that the "non-to-be-moved" point will have a 0 displacement.

As a result, a deformation of the model is obtained without creating new topological elements on the model.

Fig. 15 is a view showing a moving tooth. On the left side, the tooth, i.e. its crown and root, is moved with the positioning tool. On the right, the crown is moved and the tissue is deformed.

With all teeth planned to move, the method now has final tooth positions of both the crown and the root, final deformation of the soft tissue. Thus, for each of the teeth or groups of teeth, the movement can be quantified as three components: translation, rotation about the tooth's long or centerline, and tilting in the buccal or medial to lateral direction.

A movement plan is now created for all teeth or groups of teeth. The total number of steps for all tooth movements is determined by the maximum translation and rotation of the teeth and the movement that is experimentally allowed in one step, typically 0.2 mm. This may also be adjusted by the user according to bone density and patient age. The system will then push the movement of each tooth linearly or non-linearly inward.

There may be various strategies to plan the movement of the teeth. As a general rule, before, during or after a movement plan, several things will be done:

1. this method will use the final tooth position to determine if interproximal stripping or slicing (IPR) needs to be performed, which is a technique that reduces the width of the tooth to create some space for moving the tooth. The amount of collision between the final positions of essentially two adjacent teeth is considered to be the IPR value. 2. It is necessary to check whether there is a collision between the crown and the root. A collision value is considered invalid if it is greater than the planned IPR. The plan will need to be modified. 3. The tissue deformation was re-evaluated for each step.

FIG. 16 is a graph illustrating a function for defining the displacement of a point on a tissue region relative to the distance between the point and the tooth boundary.

Fig. 17 is a view showing the movement of a tooth in CT tomography.

After all tooth movements have been planned, the method will generate a series of models to represent each step of tooth movement. The model for each step will be a combination of the movement of the crown and the deformed soft tissue. If desired, the user may create some additional geometric features on the model, commonly referred to as attachments, and may assist in the movement of the teeth. FIG. 18 is a view showing an attachment designed to assist in moving teeth.

There are two ways to make the final appliance.

The first method is to create a series of base models and use thermoforming techniques to create an appliance, which is a shell that can be matched to the models. The series of models will be output as a digital file format and may then be sent to a 3D printer, a rapid prototyping machine, CNC or any other device that can make a physical model from a digital file.

Each base mold may be placed on a thermoforming machine that heats and draws the plastic film into the mold to create the shell mold. The inner surface of the shell model represents not only the target position of the tooth surface of the corresponding step, but also possible tissue deformations. The model may be trimmed to the tooth boundaries or include some tissue regions. The result is a one step appliance.

When the shell model of step N +1 is applied to the base model of step N, the difference in shape between the inner surface of the shell and the outer surface of the base will create a force on the model and will therefore be able to move the actual teeth at that step.

Since the shape differences between the shell model and the base model create forces that move the teeth, any further deformation of the base model may result in other shape differences on the shell model and thus additional forces in the process.

Accordingly, an embodiment of the method is to provide a software tool to modify the base model prior to fabricating the orthotic using thermoforming. For example, a local deformation operation that may create a small dent in the model will result in an inward bulge on the appliance model, which may result in additional force pushing the teeth in the direction of the bulge.

In fig. 19a, the shell model or appliance is shown in dashed lines and the teeth under the appliance are shown in solid lines. The deflection of the surface creates a force that moves the teeth as indicated by the arrows. Figure 19b is a diagram showing an original tooth model, a tooth model with local deformation, an appliance made from the deformation model applied to the actual teeth, and thus the raised area producing additional force to move the teeth.

The second method is to directly design a shell model for each step of the base model. The system provides a tool for the user to specify the area where the shell model will cover, or simply use, a collection of crown surfaces. The area is extracted and thickened to make the appliance. The final shell model will match most of the contours of the tooth surface and the attachment, but may not reflect all of the geometric details, nor is it necessary to do so.

Figure 20 is an illustration showing that the geometry of the appliance is not an exact match of the combination of teeth.

As with the first approach, a user software tool is provided to deform the base model before the shell is generated or to deform the shell model after it is created. The shell model is further sent to a manufacturing facility to make the final appliance.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

1. A method of making an appliance, comprising:

receiving a CT scan of a dental structure of a patient's oral cavity, the CT scan obtained when a jaw of the patient has a first jaw opening angle;

receiving an optical scan of the dental structure of the patient's oral cavity, the optical scan being obtained when the patient's jaw has a second jaw opening angle; the second jaw opening angle is different from the first jaw opening angle;

registering the CT scan and the optical scan, creating a virtual joint based on the CT scan and the optical scan: generating axes of temporomandibular joints of dental structures in the patient's oral cavity from the CT scan and the optical scan, and applying the axes in creating the virtual joints;

building an initial model of the dental structure of the patient's oral cavity based on the CT scan and the optical scan, comprising: segmenting the tooth data of the CT scan to obtain a segmented CT scan, wherein the segmented CT scan comprises crown data and root data, segmenting the crown data of the optical scan to obtain a segmented optical scan, wherein the segmented optical scan comprises soft tissue data; the establishing the initial model of the dental structure of the patient's oral cavity is based on the segmented CT scan and the segmented optical scan;

simulating tooth movement to produce a final model of the dental structure of the patient's oral cavity after the desired treatment, the simulated tooth movement being based on adjustment of the virtual joints and adjustment of individual tooth or group of teeth movement, wherein adjustment of the virtual joints includes adjusting joint positions of the jaw to determine an optimal target position for the entire jaw, and adjusting joint angles; the adjustment of the individual tooth or group of teeth movement is repositioning of individual teeth or groups of teeth to simulate treatment results, including: displaying each of the teeth or groups of teeth as a combination of a tooth root and a crown, or a combination of CT data and optical data, showing how the tooth root moves accordingly as the tooth moves; the movement can be displayed in CT slices and 3D space; in CT tomography, the user can assess the bone density of the area around the tooth and determine that movement is easy or difficult; in 3D space, any possible collision of the crown and the root can be seen;

generating a plurality of intermediate models of the dental structure of the patient's oral cavity representing successive tooth movements from the initial model to the final model, and,

preparing a dental appliance based on the plurality of intermediate models of the dental structure of the patient's oral cavity.

2. The method of making an appliance of claim 1, wherein the difference between the first and second jaw angles is 1 degree or greater.

3. The method of making an appliance of claim 1, wherein the CT scan and the optical scan are both displayed in 3D and 2D images, the 3D and 2D images including data of a region of a jaw bone surrounding the tooth, and the tooth repositioning dental treatment is evaluated against the data of the region of the jaw bone surrounding the tooth.

4. The method of claim 1, wherein a plurality of teeth can be moved as a single entity in the tooth repositioning dental treatment.

5. A method of making an appliance, comprising:

receiving a scan of a dental structure of a patient's oral cavity at a first jaw opening angle,

receiving a scan of dental structures in the patient's oral cavity at a second jaw opening angle,

registering the scan of the first jaw opening angle and the scan of the second jaw opening angle,

establishing an initial model of the dental structure of the patient's oral cavity based on the scan of the first jaw opening angle and the scan of the second jaw opening angle,

simulating tooth movement to produce a final model of the dental structure of the patient's mouth after the desired treatment,

generating a plurality of intermediate models of dental structures of the patient's oral cavity representing successive tooth movements from the initial model to the final model, and

preparing a dental appliance based on the plurality of intermediate models of the dental structure of the patient's oral cavity,

wherein a difference between the first and second jaw opening angles is 1 degree or greater;

the method further comprises, during the registration:

creating a virtual joint based on both the scan of the first jaw opening angle, the scan of a second jaw opening angle;

and, the simulated tooth movement is based on the adjustment of the virtual joint and the adjustment of the individual tooth movement;

the method further comprises:

generating an axis of a temporomandibular joint of the dental structure of the patient's oral cavity from both the scan of the first jaw opening angle, the scan of the second jaw opening angle, and

applying the axis when creating the virtual joint.

6. The method of making an appliance of claim 5, further comprising:

segmenting the tooth data of the first jaw opening angle scan to obtain a segmentation scan of the first jaw opening angle, an

Segmenting crown data of the second opening angle scan to obtain a segmentation scan of the second opening angle.

7. The method of making an appliance of claim 6, wherein the establishing an initial model of the dental structure of the patient's oral cavity is based on both the segmentation scan of the first jaw opening angle and the segmentation scan of the second jaw opening angle.

8. The method of making an appliance of claim 5, wherein the scan of the dental structure of the patient's oral cavity is a CT scan or an optical scan.

9. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method of any one of claims 1 to 4 or of any one of claims 5 to 8.