Technical Field
In digital orthodontic or prosthetic design, good tooth arrangement or prosthesis design needs to meet the requirement that no occlusion interference of teeth is generated in the mandibular movement process, patients with abnormal condylar positions need to reconstruct mandibular jaw positions, and some patients need to design occlusal jumps in the vertical or sagittal direction of the mandible, i.e. small amplitude of mandibular rotation or protrusion movement, so we need to restore true mandibular movement as much as possible. During mandibular movement, the center of rotation of the condyles of the temporomandibular joint, the anterior condylar track slope and the lateral condylar track slope are important mandibular movement parameters.
Conventional method utilizes
The frame simulates the movement of the lower jaw. Firstly, the three-dimensional position relation between the dentition and bilateral condyles is obtained through the face arch, and the three-dimensional position relation is transferred into
The three-dimensional position relationship between the tooth model on the rack and the bilateral condylar ball is then
The shelf is provided with a forward-extending condyle guiding inclination and a lateral condyle guiding inclination to respectively simulate the forward-extending condyle path inclination and the lateral condyle path inclination of the condyles, so that the opening and closing movement, the forward-extending movement and the lateral movement of the lower jaw are simulated.
In digital oral design, the maxilla, the mandible, the upper dentition and the lower dentition can be directly reconstructed in three dimensions through CBCT to truly reduce the temporomandibular joint without the need of complicated face arch transfer and upper arch transfer
![Figure BDA0003654060960000014](https://patentimages.storage.***apis.com/af/d9/00/57cbeb9cd64853/BDA0003654060960000014.png)
The simulation is carried out by a rack. However, the temporomandibular joint reconstructed by CBCT is static, and how to acquire the motion parameters of the temporomandibular joint to drive mandibular motion is a problem to be solved. The existing digital solution is to be transportedCombining the dynamic face arch and the CBCT, and endowing the motion parameters of the temporomandibular joint acquired by the dynamic face arch to the CBCT model. However, the exercise facebow equipment is expensive, and in addition, a plurality of steps such as equipment installation, mandibular movement data acquisition, movement data and CBCT model registration are needed to realize mandibular movement simulation, which is not beneficial to popularization and development in medical units.
In recent years, a method of calculating temporomandibular joint movement parameters using two CBCT images has been proposed (for example, see patent document 1 below). In the above method, the rotation center of the condyle and the condyle track inclination are calculated using the temporomandibular joint positions at the closed position and the open position. However, since CBCT is a radioactive X-ray, the greatest disadvantage of this method is the additional radiation dose damage to the patient from the secondary radiation. In addition, the temporomandibular joint movement parameters which can be calculated by the method are limited, if the opening position is mandibular small opening movement, the condyles are approximately in pure rotational movement, the method can only calculate the rotation center of the condyles and cannot obtain the condylar track inclination, if the opening position is mandibular large opening movement, the condyles are in composite movement with rotation and forward movement at the same time, and the rotation center of the condyles and the condylar track inclination do not have unique solutions when the rotation center and the condylar track inclination are calculated by the images of the closed opening position and the two images of the opening position. The method also fails to obtain the anterior condylar slope of the anterior motion and the lateral condylar slope of the lateral motion.
Therefore, how to better acquire temporomandibular joint movement parameters to simulate mandibular movement is a problem to be solved.
Prior Art
Patent document 1: CN111870270A
Disclosure of Invention
In view of the problems in the prior art, the inventors of the present application have recognized a need for a simpler, safer, and more universally applicable method of acquiring temporomandibular joint movement parameters. Through research, a method for acquiring temporomandibular joint movement parameters based on CBCT and a digital dental model is found, the method only needs to shoot the CBCT once, and extra X-ray radiation dose is not needed; direct three-dimensional reconstruction of temporomandibular joint by CBCT replacing facebow metastases
A process of racking; in addition, combining multiple mandibular movements
Digital dental cast of bits, restoring a plurality
The temporomandibular joint image can comprehensively acquire temporomandibular joint parameters and replace part of functions of the sports face bow.
In order to achieve the purpose, the invention adopts the technical scheme that:
a method for acquiring temporomandibular joint movement parameters based on CBCT and a digital dental model comprises the following steps:
(1) capturing images
Collecting a skull CBCT image at a closed position or a clinically established special position by using CBCT equipment;
collecting the conventional closed position, open position and protrusion by using a scanning device
Position and side
Digital dental model data of the position, or special closed position, open position, protrusion established by clinician
Position and side
Digital dental model data of the bits, the digital dental model comprises an upper jaw dental model and a lower jaw dental model;
(2) image registration
The upper jaw dental model is registered to ensure that the mouth is closed, the mouth is opened and the mouth is stretched forwards
Position and side
Overlapping the lower jaw dental model to the same coordinate system;
reconstructing a mandible model image V0 containing the lower dentition from the CBCT image;
registering the mandible model to a mandible dental model at a closed position through rotation and translation to obtain a mandible model image V1;
registering the mandible model to a mandible dental model at an opening position through rotation and translation to obtain a mandible model image V2;
mandible model registration to protrusion by rotation and translation
Obtaining a mandible model image V3 by the mandibular dental model;
mandible model is registered to left side by rotation and translation
Obtaining a mandible model image V4 by the mandibular dental model;
mandible model registration to right side by rotation and translation
Obtaining a mandible model image V5 by the mandibular dental model;
(3) parameter calculation
Calculating the condylar rotation center of the temporomandibular joint through the mandibular bone images V1 and V2;
calculating the anterior extensor condylar slope of the temporomandibular joint from the mandible images V1 and V3;
calculating the lateral condyle inclination of the right side of the temporomandibular joint through the mandible images V1 and V4;
from the mandible images V1 and V5, the lateral condyle inclination on the left side of the temporomandibular joint is calculated.
Further, the visual field range of the skull CBCT image in step (1) includes condylar and inferior dentition data.
Further, in the step (1), the digital dental model can be obtained by directly scanning dentition through an intraoral scanning device, or can be obtained by scanning a dental impression, a plaster dental model and a dental model through an extraoral scanning device
The bit record is obtained indirectly.
Further, in the step (1), the closed position is the cusp interlacing
In the position of central relation, the opening position is the position with the lower jaw opening range less than 40mm, and the lower jaw is stretched forwards
The position is any position of the mandible which is protrudingly moved to the opposite edges of the upper incisor and the lower incisor or the maximum protrusive position of the mandible or in the process of protrudingly moving set according to requirements, the side
The position is any position in the lateral movement process of the lower jaw when the lower jaw moves to the position opposite to the upper cuspid and the lower cuspid on one side or the maximum lateral position of the lower jaw or the lateral movement process set according to requirements.
Further, in the step (1), the opening positions are one or more than two and extend forwards
The bits are one or more than two, left side
One or more than two bits on the right side
The number of bits is one or more than two.
Further, in the step (2), the registration method of the mandibular dental model and the mandibular dental model is registration by using a crown surface of the mandibular dental train, and may also add a crown surface of the maxillary dental train for registration, and may also perform registration by using the auxiliary mark points.
Further, in the step (3), the anterior condyle inclination is an angle between a line connecting the condylar rotation centers of the mandibular images V1 and V3 in the sagittal plane and the horizontal reference plane.
Further, in the step (3), the right lateral condyle inclination is an angle between a line connecting the condylar rotation centers of the mandible images V1 and V4 in the horizontal plane and the sagittal plane, and the left lateral condyle inclination is an angle between a line connecting the condylar rotation centers of the mandible images V1 and V5 in the horizontal plane and the sagittal plane.
The invention has the beneficial effects that: the CBCT and the digital dental model are used as clinical routine examination data in the digital oral diagnosis and treatment, the CBCT only needs to be shot once, the dental model scanning is generally developed clinically, no radioactivity exists, the dental models with a plurality of occlusion positions can be obtained through multiple times of scanning, and a method for obtaining occlusion records by replacing a traditional impression mold is replaced. After the mandibular movement is realized through simulation, the design of digital treatment schemes such as orthodontics, restoration and the like can be more accurately guided, such as the setting of a lower jaw sagittal leading position or a vertical occlusion jumping position, the examination of occlusion interference points of teeth in the mandibular movement process after the orthodontics tooth arrangement target position or the restoration design and the like, so that a patient can obtain better tooth arrangement and occlusion, and accurate oral cavity digital treatment is realized.
Detailed Description
The following description of the embodiments of the present invention will be made with reference to the accompanying drawings in order to better illustrate the contents of the present invention, but the illustrated embodiments are only examples and do not limit the scope of the invention.
The method for acquiring temporomandibular joint movement parameters based on CBCT and digital dental model, as shown in figure 1, specifically comprises the following steps:
(1) capturing images
Acquiring a skull CBCT image of a closed position or a clinically established special position by using CBCT equipment, wherein the range of the CBCT image comprises the whole dentition and temporomandibular joint, and at least comprises an inferior dentition and a condyle;
utilizes scanning equipment to collect routine closed position, open position and forward extension
Position and side
Digital dental model data of the position, or special closed position, open position and protrusion established by a clinician
Position and side
Digital dental model data of the bits, the digital dental models including upper dental models and lower dental models;
specifically, the upper dentition is scanned to obtain the upper jaw dental model, the lower dentition is scanned to obtain the lower jaw dental model, and then any one of the upper and lower dental models is scanned
The time of the position includes the images of the upper and lower dentitions at the same time, and the image is recorded
The relative position of the upper and lower dentitions in position is obtained
The digital dental model data in time of position, aiming at the same set of dentition, after respectively scanning upper dentition and lower dentition, if a plurality of dentitions are recorded simultaneously
The upper and lower dentition images in the time of the position can obtain a plurality of
Digital dental model data in bit;
specifically, the closed position is the crossing of the cusps
In the middle or on the cusps, when the cusps are staggered
Position andwhen the difference of the median relation position is obvious, the staggering of the cusps is obtained at the same time
A dental cast in position and in the median relationship;
the opening position is a position with a mandibular opening range smaller than 40mm, and when the small opening moves, the motion of the condyles is closer to the pure rotation motion, so that the condylar rotation center can be better positioned;
extending forwards
The position is that the mandible is extended forwards to move to the position of the upper incisor counter-blade and the lower incisor counter-blade
The patient can order the mandible to move forwards to the maximum forwards extending position or any position in the forwards extending process set according to the requirement;
side part
The position is any position in the lateral movement process when the lower jaw moves laterally to the position where the upper cuspid and the lower cuspid tooth cusps on one side are opposite or the position of the maximum lateral side of the lower jaw or is set according to the requirement;
in addition, because the motion parameters of the condyles are not constant values during the mandibular motion, the opening position and the protrusion are not constant values
Position, left side square
Right side and side of the table
One or more than two positions can be collected, and when a plurality of positions are collected continuously, the dynamic change of the motion parameter value of the condylar process can be obtained, so that the function of the motion face arch is as close as possible, and the real mandible motion is restored to the maximum extent.
(2) Image registration
Firstly, the upper jaw dental model is registered to ensure that the mouth is closed, the mouth is opened and the mouth is stretched forwards
Position and side
The mandibular cast in position is superimposed under the same coordinate system (see figure 2);
secondly, reconstructing a mandible model image V0 containing the lower dentition from the CBCT image, wherein the image is a shell-shaped three-dimensional model consistent with the digital dental model;
then, with the crown of the dentition as a registration region, the mandibular model is registered to the mandibular model in the closed position by rotation and translation, resulting in a mandibular model image V1 (see fig. 3);
using the crown of the dentition as a registration area, the mandible model is registered to a mandible model at an opening position through rotation and translation, and a mandible model image V2 is obtained;
the mandible model was registered to protrusion by rotation and translation with the crowns of the dentition as registration areas
Obtaining a mandible model image V3 by the mandible model of the lower jaw;
the mandible model was registered to the left side by rotation and translation with the crowns of the dentition as registration areas
Obtaining a mandible model image V4 by the mandibular dental model;
the mandible model was registered to the right side by rotation and translation with the crowns of the dentition as registration areas
Obtaining a mandible model image V5 by the mandibular dental model;
in addition, if the CBCT image also comprises the upper dentition, the whole dentition and the lower jaw bone can be reconstructed, the closed CBCT image and the closed dental model are registered by taking the dental crowns of the whole dentition as registration areas, and compared with the registration by using the dental crowns of the lower dentition, the registration by using the dental crowns of the whole dentition increases the area of the registration areas, so that the registration accuracy can be improved;
for opening position and forward extension
Position and side
Because the occlusion of the upper and lower dentitions is inconsistent with the occlusion of the dentition in the CBCT image, the registration of the whole dentition cannot be directly carried out, at the moment, a space transformation matrix from the lower dentition of the closed-position dentition to the lower dentition of the open-position dentition is endowed to the CBCT image registered with the closed-position dentition, the registration of the open-position dentition and the CBCT image can be indirectly realized, and the forward extension can be indirectly realized by the same method
Registration and lateral side of positioning dental model and CBCT image
Registering the dental model with the CBCT image;
in addition, registration can also be carried out by means of auxiliary mark points, for example, 3 radioresistant marker balls are placed on the lower jaw, then CBCT shooting and dental model scanning are carried out, and then registration of the CBCT model and the digital dental model is realized by taking the radioresistant marker balls as registration marker points.
(3) Parameter calculation
Calculating the condylar rotation center of the temporomandibular joint through the mandibular images V1 and V2, namely, if the image V1 rotates around the rotation center by a certain angle, the image V2 (see FIG. 4) can be reached, if the image V1 is represented by a line segment AB on the sagittal plane, and the corresponding line segment in the image V2 is CD, the condylar rotation center is the intersection point of the perpendicular bisector of the line segment AC and the perpendicular bisector of the line segment BD, and the connecting line of the rotation centers of the condyles on the two sides is the condylar hinge axis;
calculating the inclination of the protrusive condyle of the temporomandibular joint by using the mandibular images V1 and V3, which is the angle between the line connecting the centers of rotation of the condyles of the mandibular images V1 and V3 on the sagittal plane and the horizontal reference plane (see FIG. 5);
calculating the lateral condyle inclination of the right side of the temporomandibular joint through the mandible images V1 and V4, wherein the lateral condyle inclination is the included angle between the connection line of the condylar rotation centers of the mandible images V1 and V4 on the horizontal plane and the sagittal plane;
the lateral condyle inclination of the left side of the temporomandibular joint is calculated through the mandibular images V1 and V5, which is the angle between the line connecting the centers of rotation of the condyles of the mandibular images V1 and V5 in the horizontal plane and the sagittal plane.
The figures are only by way of example and the invention is not limited to the embodiments shown in the figures. Any equivalent modifications and substitutions to those skilled in the art are also within the scope of the present invention. Accordingly, equivalent changes and modifications made without departing from the spirit and scope of the present invention should be covered by the present invention.