High-precision acquisition method for three-dimensional movement of lower jaw based on jaw fork registration

Abstract

The application discloses a kind of high-precision acquisition methods of mandibular three-dimensional movement based on jaw fork registration, belong to the field of measurement technology.The application fully considers the dentition characteristics of volunteers, designs and manufactures personalized jaw fork for each volunteer, there are three recesses on the jaw fork, which are not coplanar, used for placing reflective marker balls, the recess diameter is consistent with the diameter of the ball.Through intraoral scanning, the personalized jaw fork that is fully adhered to the tooth surface is obtained based on the upper dentition model of the volunteer, to ensure that the jaw fork can be worn smoothly on the dentition, greatly improve the accuracy of collected data, avoid volunteers needing to take CT multiple times during the process of collecting mandibular kinematics data.The application uses three-dimensional infrared motion capture method to build a mandibular movement acquisition system, avoids the problem of multiple CT shooting caused by volunteers performing mandibular movement tracking each time through jaw fork registration, realizes high-precision acquisition of mandibular three-dimensional movement.The application has the advantages of convenient and fast use, small radiation, safety, high collection accuracy.

Description

Technical Field

[0001] This invention belongs to the field of measurement technology, and specifically relates to a high-precision method for acquiring three-dimensional motion data of the human mandible. Background Technology

[0002] Mandibular movement is fundamental to many oral movements. Its forms are complex and influenced by numerous factors, including the temporomandibular joint, ligaments, muscle groups, dentition, and nerves. The driving and stabilizing mechanisms of mandibular movement are not yet fully understood. High-precision mandibular motion acquisition systems provide a research foundation and data support for the diagnosis and pathogenesis of diseases related to occlusion, masticatory muscles, and the temporomandibular joint. They are important tools for evaluating the motor function of the stomatognathic system and assist in the screening and diagnosis of related diseases. Traditional mechanical mandibular motion recording systems record the condylar movement trajectory during mandibular movements using a tracing needle and tracing plate. However, their numerous components and complex installation increase the difficulty of clinical operation, limiting their clinical application and widespread use. Summary of the Invention

[0003] The main objective of this invention is to provide a high-precision acquisition method for three-dimensional mandibular motion based on jaw fork registration. A mandibular motion acquisition system is built using a three-dimensional infrared motion capture method. By using jaw fork registration, the problem of multiple CT scans caused by each mandibular motion tracking of volunteers is avoided, thus achieving high-precision acquisition of three-dimensional mandibular motion. It has the advantages of being convenient and quick to use, having low radiation, being safe, and having high acquisition accuracy.

[0004] The objective of this invention is achieved through the following technical solution.

[0005] This invention discloses a high-precision method for acquiring three-dimensional mandibular motion based on jaw fork registration, comprising the following steps:

[0006] Step 1: Fabrication of a personalized jaw fork for indirect registration. The volunteer's upper dentition model is obtained via intraoral scanning in software, and a personalized jaw fork is designed in 3D geometric modeling software to ensure a proper fit between the fork and the dentition. The jaw fork has three non-coplanar grooves for placing reflective marker balls, with the groove diameter matching the ball diameter.

[0007] Step 2: Fabrication of maxillary and mandibular tracking plates for collecting mandibular movement data. Tracking plates are fabricated using digital models of the maxilla and mandible, each with three grooves for placing reflective marker balls. During mandibular movement data collection, the maxillary and mandibular tracking plates are respectively bonded and fixed to the volunteer's upper and lower dentition using fluidized resin.

[0008] Step 3: A mandibular motion acquisition system based on jaw fork registration is constructed using a three-dimensional infrared motion capture method. This system includes an array of three infrared cameras, a personalized jaw fork, a maxillary motion tracking plate, a mandibular motion tracking plate, and several reflective marker balls. The reflective marker balls are placed in grooves within the maxillary and mandibular motion tracking plates and the personalized jaw fork, and are fixed using fluid resin. During the volunteer's mandibular movements, the infrared cameras accurately capture the position and posture changes of the reflective marker balls, record the coordinate changes of the ball's center, and transmit the data in real time to a data processing and display terminal.

[0009] Step 4: Perform CBCT scans on the volunteer's jawbone and personalized jawbone fracture separately. During the CBCT scan of the jawbone, the volunteer should maintain intercuspal position. Import the DICOM format image data obtained from the CBCT scan into image reconstruction software to reconstruct the jawbone and personalized jawbone fracture.

[0010] For ease of operation, Mimics is the preferred image reconstruction software.

[0011] As a preferred choice, geomagic is selected as the 3D geometric modeling software.

[0012] Step 5: Import the reconstructed geometric file into a 3D open-source geometric processing system. Use the point cloud registration function in the image reconstruction software to register the personalized jawbone and the volunteer's maxilla. Import the registered jawbone and jawbone geometric file into image processing software. Manually identify the coordinates of the centers of the three reflective marker spheres on the personalized jawbone, and the coordinates of key feature points on the maxilla and mandible, all within the same coordinate system.

[0013] Step Six: Based on the coordinates of the centers of the three reflective marker spheres on the jaw fork obtained in Step Five, establish a local coordinate system for the jaw fork, and obtain the coordinates of key feature points on the maxilla and mandible in the local coordinate system of the jaw fork. The coordinates of the key feature points on the maxilla in the local coordinate system of the jaw fork remain unchanged during mandibular movement.

[0014] Step 7: Volunteers simultaneously wear the maxillary tracking board and the personalized jaw fork, and perform mandibular movements under the guidance of an infrared camera array. The coordinates of the centers of the reflective marker balls on the personalized jaw fork and the maxillary tracking board are captured by the infrared camera array in the same coordinate system. Local coordinate systems for the jaw fork and the maxillary tracking board are established separately. The coordinates of the key feature points on the maxilla and mandible obtained in Step 6 in the local coordinate system of the jaw fork are transformed to the local coordinate system of the maxillary tracking board.

[0015] The coordinates of key feature points on the maxilla and mandible are transformed from the local coordinate system of the mandibular fork to the local coordinate system of the maxillary tracking plate using formulas (1) and (2):

[0016] Define the origin of the local coordinate system of the maxillary tracking plate as: The origin of the local coordinate system of the jaw fork is Local coordinate system of maxillary tracking plate Local coordinate system of jaw fork With infrared coordinate system The following linear relationship is satisfied:

[0017] , (1)

[0018] in, It is used to describe the local coordinate system of the maxillary tracking plate. Parameters; It is used to describe the local coordinate system of the jaw fork. The parameters.

[0019] Define the coordinates of point P in the local coordinate system of the jaw fork as follows: Then the coordinates of point P in the local coordinate system of the maxillary tracking plate are... for:

[0020] (2)

[0021] Step 8: The volunteer removes the mandibular fork, and while keeping the position of the maxillary tracking board unchanged as in Step 7, puts on the mandibular tracking board and holds it in the intercuspal position for 3-5 seconds. Obtain the coordinates of the center of the reflective marker ball on the maxillary and mandibular tracking boards in the same coordinate system. Based on the coordinates of the center of the reflective marker ball, establish the local coordinate system of the maxillary tracking board and the local coordinate system of the mandibular tracking board respectively. Transform the coordinates of the key feature points on the mandible obtained in Step 7 from the local coordinate system of the maxillary tracking board to the local coordinate system of the mandibular tracking board.

[0022] The coordinates of key feature points on the mandible are transformed from the local coordinate system of the maxillary tracking plate to the local coordinate system of the mandibular tracking plate using formulas (3) and (4):

[0023] Define the origin of the local coordinate system of the maxillary tracking plate as: The origin of the local coordinate system of the mandibular tracking plate is... Local coordinate system of maxillary tracking plate and the local coordinate system of the mandibular tracking plate With infrared coordinate system The following linear relationship is satisfied:

[0024] , (3)

[0025] in, It is used to describe the local coordinate system of the maxillary tracking plate. Parameters; It is used to describe the local coordinate system of the mandibular tracking plate. The parameters.

[0026] Given that the coordinates of point P in the local coordinate system of the maxillary tracking plate are: Then the coordinates of point P in the local coordinate system of the mandibular tracking plate are... for:

[0027] (4)

[0028] According to the coordinate transformation described in equations (3) and (4), the coordinates of key feature points on the mandible in the local coordinate system of the mandibular tracking plate are obtained. These coordinates remain unchanged during the volunteer's mandibular edge movement and functional movement.

[0029] Step 9: Volunteers simultaneously wear the maxillary tracking board and the mandibular tracking board to perform mandibular movements. The coordinates of the centers of the reflective marker balls on the maxillary and mandibular tracking boards are obtained in the same coordinate system. Based on the coordinates of the centers of the reflective marker balls, the local coordinate systems of the maxillary tracking board and the mandibular tracking board are established during the movement. The coordinates of the key feature points on the mandible obtained in Step 8 are transferred from the local coordinate system of the mandibular tracking board to the local coordinate system of the maxillary tracking board.

[0030] The coordinates of key feature points on the mandible are transformed from the local coordinate system of the mandibular tracking plate to the local coordinate system of the maxillary tracking plate using formulas (5) and (6):

[0031] The origin of the local coordinate system of the maxillary tracking plate during mandibular movement is defined as follows: The origin of the local coordinate system of the mandibular tracking plate is... Local coordinate system of maxillary tracking plate and the local coordinate system of the mandibular tracking plate With infrared coordinate system The following linear relationship is satisfied:

[0032] , (5)

[0033] in, It is used to describe the local coordinate system of the maxillary tracking plate during movement. Parameters; It is used to describe the local coordinate system of the mandibular tracking plate. The parameters.

[0034] Given that the coordinates of point Q in the local coordinate system of the mandibular tracking plate are: Then the coordinates of point Q in the local coordinate system of the maxillary tracking plate are... for:

[0035] (6)

[0036] Based on equations (1) to (6), the coordinates of the key features on the jawbone in the local coordinate system of the maxillary tracking plate at each moment during the volunteer's mandibular movement are obtained, thereby obtaining the three-dimensional motion trajectory of the key features, which is more helpful for analyzing the three-dimensional mandibular movement of the volunteer.

[0037] Beneficial effects:

[0038] 1. This invention discloses a high-precision acquisition method for three-dimensional mandibular motion based on jaw fork registration. This method obtains the upper dentition model of volunteers through intraoral scanning, designs and manufactures personalized jaw forks that fit the tooth surface for each volunteer, fully considers the personalized dentition characteristics of volunteers, ensures that the jaw fork can be stably worn on the dentition, eliminates the error caused by the fit between the tooth surface and the jaw fork, and greatly improves the accuracy of the acquired data.

[0039] 2. The present invention discloses a high-precision acquisition method for three-dimensional mandibular motion based on mandibular fork registration. It uses a personalized mandibular fork for indirect registration. Compared with the direct measurement method, it avoids the physical radiation and economic burden caused by volunteers having to undergo multiple CT scans during the mandibular kinematic data acquisition process, and is more acceptable to volunteers.

[0040] 3. The present invention discloses a high-precision acquisition method for three-dimensional mandibular motion based on jaw fork registration. It uses coordinate system transformation to obtain the three-dimensional motion trajectory of key mandibular feature points. The measurement principle is simple, the measurement method is easy to implement, and it is convenient and quick to use. Attached Figure Description

[0041] Figure 1 This invention discloses a flowchart of a high-precision acquisition method for three-dimensional mandibular motion based on mandibular fork registration;

[0042] Figure 2 This is a schematic diagram of a personalized jaw fork;

[0043] Figure 3 This is a schematic diagram of the local coordinate system of the jaw fork;

[0044] Figure 4 It is a coordinate transformation between the local coordinate system of the jaw fork and the local coordinate system of the maxillary tracking plate;

[0045] Figure 5 It is a coordinate transformation between the local coordinate system of the maxillary tracking plate and the local coordinate system of the mandibular tracking plate;

[0046] Figure 6 It is the trajectory of the lower incisor's movement;

[0047] Figure 7 The results are based on the ANB angle measurements of volunteers with jaw fork registration.

[0048] Figure 8 This is a comparison chart of the direct measurement of the movement trajectory of a point on the mandible and the registration effect of the jaw fork. Detailed Implementation

[0049] To better illustrate the purpose and advantages of the present invention, the invention will be further described below in conjunction with the accompanying drawings and examples.

[0050] Example 1:

[0051] like Figure 1 As shown in the figure, this embodiment discloses a high-precision measurement method for three-dimensional mandibular motion based on jaw fork registration. The specific implementation steps are as follows:

[0052] Step 1: Design and fabricate a personalized jaw fork for indirect registration. The volunteer's upper dentition model is obtained through intraoral scanning in software, and a personalized jaw fork is designed in 3D geometric modeling software (geomagic) to ensure a proper fit to the dentition. The jaw fork has three non-coplanar grooves for placing reflective marker spheres; the diameter of the grooves matches the diameter of the spheres. The resulting personalized jaw fork looks like this. Figure 2 As shown.

[0053] Step 2: Fabricate the maxillary and mandibular tracking plates for collecting mandibular movement data. The tracking plates are designed using digital models of the maxilla and mandible, and each plate has three grooves for placing reflective marker balls. During mandibular movement data collection, the maxillary and mandibular tracking plates are respectively bonded and fixed to the volunteer's upper and lower dentition using fluidized resin.

[0054] Step 3: A mandibular motion acquisition system based on jaw fork registration is constructed using a three-dimensional infrared motion capture method. This system includes an array of three infrared cameras, a personalized jaw fork, a maxillary motion tracking plate, a mandibular motion tracking plate, and several reflective marker balls. The reflective marker balls are placed in grooves within the maxillary and mandibular motion tracking plates and the personalized jaw fork, and are fixed using fluid resin. During the volunteer's mandibular movements, the infrared cameras can accurately capture the position and posture changes of the reflective marker balls, record the coordinate changes of the ball's center, and transmit the data in real time to a data processing and display terminal.

[0055] Step 4: Perform CBCT scans on the volunteer's jawbone and personalized jawbone fracture separately. During the CBCT scan of the jawbone, the volunteer should maintain intercuspal position. Import the DICOM format image data obtained from the CBCT scan into image reconstruction software to reconstruct the jawbone and personalized jawbone fracture. Import the reconstructed geometric files into a 3D open-source geometry processing system, and use the point cloud registration function in the image reconstruction software to register the personalized jawbone fracture with the volunteer's maxilla.

[0056] Step 5: Import the registered jawbone and jawbone geometry files into image processing software. By manually identifying the coordinates of the centers of the three reflective marker spheres on the personalized jawbone under the same coordinate system, and the coordinates of the key feature points on the maxilla and mandible, the results are shown in Table 1.

[0057] Table 1. Coordinates of the center of the reflective marker sphere and key feature points of the maxilla and mandible.

[0058]

[0059] Step Six: Based on the coordinates of the centers of the three reflective marker spheres on the jaw fork obtained in Step Five, establish the following... Figure 3 The coordinates of key feature points on the maxilla and mandible in the local coordinate system of the mandibular fork are obtained, and the results are shown in Table 2. The coordinates of the key feature points on the maxilla in the local coordinate system of the mandibular fork remain unchanged during mandibular movement.

[0060] Table 2. Coordinates of key feature points of the maxilla and mandible in the local coordinate system of the jawbone

[0061]

[0062] Step 7: Volunteers simultaneously wear the maxillary tracking board and the personalized jaw fork, and perform mandibular movements under the guidance of an infrared camera array. The coordinates of the centers of the reflective marker balls on the personalized jaw fork and the maxillary tracking board are obtained in the same coordinate system by the infrared camera array. Local coordinate systems for the jaw fork and the maxillary tracking board are established separately. The coordinates of the key feature points on the maxilla and mandible obtained in Step 6 in the local coordinate system of the jaw fork are transformed to the local coordinate system of the maxillary tracking board. The results are shown in Table 3.

[0063] The coordinates of key feature points on the maxilla and mandible are transformed from the local coordinate system of the mandibular fork to the local coordinate system of the maxillary tracking plate using formulas (1) and (2):

[0064] Define the origin of the local coordinate system of the maxillary tracking plate as: The origin of the local coordinate system of the jaw fork is Local coordinate system of maxillary tracking plate Local coordinate system of jaw fork With infrared coordinate system The following linear relationship is satisfied:

[0065] , (1)

[0066] in, It is used to describe the local coordinate system of the maxillary tracking plate. Parameters; It is used to describe the local coordinate system of the jaw fork. The parameters.

[0067] like Figure 4 As shown, the coordinates of point P in the local coordinate system of the jaw fork are defined as follows: Then the coordinates of point P in the local coordinate system of the maxillary tracking plate are... for:

[0068] (2)

[0069] Table 3. Coordinates of key feature points of the maxilla and mandible in the local coordinate system of the maxillary tracking plate

[0070]

[0071] Step 8: The volunteer removes the mandibular fork, and while keeping the position of the maxillary tracking board unchanged as in Step 7, puts on the mandibular tracking board and holds it in the intercuspal position for 3-5 seconds. Obtain the coordinates of the center of the reflective marker ball on the maxillary and mandibular tracking boards in the same coordinate system. Based on the coordinates of the center of the reflective marker ball, establish the local coordinate system of the maxillary tracking board and the local coordinate system of the mandibular tracking board respectively. Transform the coordinates of the key feature points on the mandible obtained in Step 7 from the local coordinate system of the maxillary tracking board to the local coordinate system of the mandibular tracking board.

[0072] The coordinates of key feature points on the mandible are transformed from the local coordinate system of the maxillary tracking plate to the local coordinate system of the mandibular tracking plate using formulas (3) and (4):

[0073] Define the origin of the local coordinate system of the maxillary tracking plate as: The origin of the local coordinate system of the mandibular tracking plate is... Local coordinate system of maxillary tracking plate and the local coordinate system of the mandibular tracking plate With infrared coordinate system The following linear relationship is satisfied:

[0074] , (3)

[0075] in, It is used to describe the local coordinate system of the maxillary tracking plate. Parameters; It is used to describe the local coordinate system of the mandibular tracking plate. The parameters.

[0076] like Figure 5 As shown, the coordinates of point P in the local coordinate system of the maxillary tracking plate are... Then the coordinates of point P in the local coordinate system of the mandibular tracking plate are... for:

[0077] (4)

[0078] According to the coordinate transformation described in equations (3) and (4), the coordinates of key feature points on the mandible in the local coordinate system of the mandibular tracking plate are obtained, as shown in Table 4. These coordinates remain unchanged during the volunteers’ mandibular edge movement and functional movement.

[0079] Table 4. Coordinates of key mandibular feature points in the local coordinate system of the mandibular tracking plate

[0080]

[0081] Step 9: Volunteers simultaneously wear the maxillary tracking board and the mandibular tracking board to perform mandibular movements. The coordinates of the centers of the reflective marker balls on the maxillary and mandibular tracking boards are obtained in the same coordinate system. Based on the coordinates of the centers of the reflective marker balls, the local coordinate systems of the maxillary tracking board and the mandibular tracking board are established during the movement. The coordinates of the key feature points on the mandible obtained in Step 8 are transferred from the local coordinate system of the mandibular tracking board to the local coordinate system of the maxillary tracking board.

[0082] The coordinates of key feature points on the mandible are transformed from the local coordinate system of the mandibular tracking plate to the local coordinate system of the maxillary tracking plate using formulas (5) and (6):

[0083] The origin of the local coordinate system of the maxillary tracking plate during mandibular movement is defined as follows: The origin of the local coordinate system of the mandibular tracking plate is... Local coordinate system of maxillary tracking plate and the local coordinate system of the mandibular tracking plate With infrared coordinate system The following linear relationship is satisfied:

[0084] , (5)

[0085] in, It is used to describe the local coordinate system of the maxillary tracking plate during movement. Parameters; It is used to describe the local coordinate system of the mandibular tracking plate. The parameters.

[0086] Given that the coordinates of point Q in the local coordinate system of the mandibular tracking plate are: Then the coordinates of point Q in the local coordinate system of the maxillary tracking plate are... for:

[0087] (6)

[0088] Based on equations (1) to (6), the coordinates of the key features on the jawbone in the local coordinate system of the maxillary tracking plate at each moment during the volunteer's mandibular movement are obtained, and the three-dimensional motion trajectory of the key features is obtained. Figure 6 This involves capturing the movement trajectory of the mandibular key point (mandibular incisor point) in the sagittal plane during the volunteer's mouth opening and closing movements. Based on the obtained three-dimensional movement trajectory of the mandibular key point, more three-dimensional motion information of the volunteer can be obtained. For example, the ANB angle is a measurement angle used in orthodontics to assess jawbone relationships. Figure 7 The predicted results for the ANB angle of volunteers.

[0089] In this experiment, volunteers performed four mandibular movements: intercuspal position, mouth opening and closing, teeth clenching, and lateral movement, but only one CT scan was taken. If the mandibular tracking plates dislodged during the measurement of different mandibular movements, steps seven, eight, and nine only needed to be repeated; another CT scan was not required. To ensure measurement accuracy, the error between the direct measurement result of the mandibular movement trajectory at a point on the upper jaw during the movement and the measurement result based on the jaw fork registration was calculated. The results are as follows: Figure 8 As shown, the high-precision acquisition method for mandibular three-dimensional motion based on jaw fork registration proposed in this invention can control the measurement error within 3mm. While ensuring accuracy, it greatly simplifies the operation, saves time, and avoids the radiation problems caused by multiple CT scans.

[0090] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-precision acquisition method for three-dimensional mandibular motion based on jaw fork registration, characterized in that: Includes the following steps, Step 1: Create a personalized jaw fork for indirect registration; obtain the volunteer's upper dentition model in the software through intraoral scanning, and design a personalized jaw fork in 3D geometric modeling software so that the jaw fork fits the dentition; at the same time, the jaw fork has three non-coplanar grooves for placing reflective marker balls, and the diameter of the grooves matches the diameter of the balls. Step 2: Fabricate the maxillary tracking plate and mandibular tracking plate for collecting mandibular movement data; the tracking plate is fabricated using digital models of the maxilla and mandible, and the tracking plate has three grooves for placing reflective marker balls; during mandibular movement data collection, the maxillary and mandibular tracking plates are respectively bonded and fixed to the upper and lower dentition of the volunteer using fluid resin. Step 3: Construct a mandibular motion acquisition system based on jaw fork registration using a three-dimensional infrared motion capture method. The mandibular motion acquisition system based on jaw fork registration includes an array of three infrared cameras, a personalized jaw fork, a maxillary motion tracking plate, a mandibular motion tracking plate, and several reflective marker balls. The reflective marker balls are placed in the grooves of the maxillary and mandibular motion tracking plates and the personalized jaw fork, and are fixed by fluid resin bonding. During the volunteer's mandibular movement, the infrared cameras are used to accurately capture the position and posture changes of the reflective marker balls, record the coordinate changes of the ball center, and transmit the data to the data processing and display terminal in real time. Step 4: Perform CBCT scans on the volunteer's jawbone and personalized jawbone separately. During the CBCT scan of the jawbone, the volunteer should maintain the intercuspal position. Import the DICOM format image data obtained from the CBCT scan into the image reconstruction software to reconstruct the jawbone and personalized jawbone. Step 5: Import the reconstructed geometric file into the 3D open-source geometric processing system. Based on the point cloud registration function in the image reconstruction software, realize the registration of the personalized jaw fork with the volunteer's maxilla. Import the registered jaw and jaw fork geometric file into the image processing software. By manually identifying, obtain the coordinates of the center of the three reflective marker spheres on the personalized jaw fork and the coordinates of the key feature points on the maxilla and mandible in the same coordinate system. Step 6: Based on the coordinates of the centers of the three reflective marker balls on the jaw fork obtained in Step 5, establish a local coordinate system for the jaw fork, and obtain the coordinates of key feature points on the maxilla and mandible in the local coordinate system for the jaw fork; wherein, the coordinates of the key feature points on the maxilla in the local coordinate system for the jaw fork remain unchanged during the mandibular movement. Step 7: Volunteers wear the maxillary tracking board and the personalized jaw fork simultaneously, and perform mandibular movements under the guidance of an infrared camera array. The coordinates of the centers of the reflective marker balls on the personalized jaw fork and the maxillary tracking board are captured by the infrared camera array in the same coordinate system. Local coordinate systems for the jaw fork and the maxillary tracking board are established separately. The coordinates of the key feature points on the maxilla and mandible obtained in Step 6 in the local coordinate system of the jaw fork are transformed to the local coordinate system of the maxillary tracking board. Step 8: The volunteer removes the mandibular fork, and while keeping the position of the maxillary tracking board unchanged as in Step 7, puts on the mandibular tracking board and holds it in the intercuspal position for 3-5 seconds. Obtain the coordinates of the center of the reflective marker ball on the maxillary and mandibular tracking boards in the same coordinate system. Based on the coordinates of the center of the reflective marker ball, establish the local coordinate system of the maxillary tracking board and the local coordinate system of the mandibular tracking board respectively. Transform the coordinates of the key feature points on the mandible obtained in Step 7 in the local coordinate system of the maxillary tracking board to the local coordinate system of the mandibular tracking board. Step 9: Volunteers simultaneously wear the maxillary tracking board and the mandibular tracking board to perform mandibular movements. The coordinates of the centers of the reflective marker balls on the maxillary and mandibular tracking boards are obtained in the same coordinate system. Based on the coordinates of the centers of the reflective marker balls, the local coordinate systems of the maxillary tracking board and the mandibular tracking board are established during the movement. The coordinates of the key feature points on the mandible obtained in Step 8 are transferred from the local coordinate system of the mandibular tracking board to the local coordinate system of the maxillary tracking board.

2. The high-precision acquisition method for three-dimensional mandibular motion based on jaw fork registration as described in claim 1, characterized in that: Mimics was chosen for image reconstruction, and geomagic was chosen for 3D geometric modeling.

3. A high-precision acquisition method for three-dimensional mandibular motion based on jaw fork registration as described in claim 1 or 2, characterized in that: Step seven is implemented as follows: The coordinates of key feature points on the maxilla and mandible are transformed from the local coordinate system of the mandibular fork to the local coordinate system of the maxillary tracking plate using formulas (1) and (2): Define the origin of the local coordinate system of the maxillary tracking plate as: The origin of the local coordinate system of the jaw fork is Local coordinate system of maxillary tracking plate Local coordinate system of jaw fork With infrared coordinate system The following linear relationship is satisfied: ， （1） in, It is used to describe the local coordinate system of the maxillary tracking plate. Parameters; It is used to describe the local coordinate system of the jaw fork. Parameters; Define the coordinates of point P in the local coordinate system of the jaw fork as follows: Then the coordinates of point P in the local coordinate system of the maxillary tracking plate are... for: （2）。 4. The high-precision acquisition method for mandibular three-dimensional motion based on jaw fork registration as described in claim 3, characterized in that: Step eight is implemented as follows: The coordinates of key feature points on the mandible are transformed from the local coordinate system of the maxillary tracking plate to the local coordinate system of the mandibular tracking plate using formulas (3) and (4): Define the origin of the local coordinate system of the maxillary tracking plate as: The origin of the local coordinate system of the mandibular tracking plate is... Local coordinate system of maxillary tracking plate and the local coordinate system of the mandibular tracking plate With infrared coordinate system The following linear relationship is satisfied: ， （3） in, It is used to describe the local coordinate system of the maxillary tracking plate. Parameters; It is used to describe the local coordinate system of the mandibular tracking plate. Parameters; Given that the coordinates of point P in the local coordinate system of the maxillary tracking plate are: Then the coordinates of point P in the local coordinate system of the mandibular tracking plate are... for: （4） According to the coordinate transformation described in equations (3) and (4), the coordinates of key feature points on the mandible in the local coordinate system of the mandibular tracking plate are obtained. These coordinates remain unchanged during the volunteer's mandibular edge movement and functional movement.

5. The high-precision acquisition method for three-dimensional mandibular motion based on jaw fork registration as described in claim 4, characterized in that: Step nine is implemented as follows: The coordinates of key feature points on the mandible are transformed from the local coordinate system of the mandibular tracking plate to the local coordinate system of the maxillary tracking plate using formulas (5) and (6): The origin of the local coordinate system of the maxillary tracking plate during mandibular movement is defined as follows: The origin of the local coordinate system of the mandibular tracking plate is... Local coordinate system of maxillary tracking plate and the local coordinate system of the mandibular tracking plate With infrared coordinate system The following linear relationship is satisfied: ， （5） in, It is used to describe the local coordinate system of the maxillary tracking plate during movement. Parameters; It is used to describe the local coordinate system of the mandibular tracking plate. Parameters; Given that the coordinates of point Q in the local coordinate system of the mandibular tracking plate are: Then the coordinates of point Q in the local coordinate system of the maxillary tracking plate are... for: （6） Based on equations (1) to (6), the coordinates of the key features on the jawbone in the local coordinate system of the maxillary tracking plate at each moment during the volunteer's mandibular movement are obtained, and the three-dimensional motion trajectory of the key features is obtained.

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