CN111437047A

CN111437047A - Rotation center design inspection method, shell-shaped dental instrument design and preparation method

Info

Publication number: CN111437047A
Application number: CN202010250530.7A
Authority: CN
Inventors: 於路; 王心军; 姚峻峰
Original assignee: Shanghai Smartee Denti Technology Co Ltd
Current assignee: Shanghai Smartee Denti Technology Co Ltd
Priority date: 2020-04-01
Filing date: 2020-04-01
Publication date: 2020-07-24
Anticipated expiration: 2040-04-01
Also published as: CN111437047B

Abstract

The invention provides a method for designing and checking a rotation center, a method for designing and manufacturing a shell-shaped dental instrument, wherein the method for designing and checking the rotation center comprises the following steps: the method comprises the steps of classifying single digital dental crown models, fitting a long shaft of the single digital dental crown model, determining an impedance center of the digital dental crown model, simulating a tooth arrangement design of the digital dental crown model and optimizing and adjusting a rotation center, wherein the preset position of the rotation center is checked based on the ratio of the torque generated by applying the digital dental crown model to the balance torque generated by applying the digital dental crown model to a digital dental appliance and the rotation amount design in the tooth arrangement design so as to realize the optimizing and adjusting of the rotation center. Through the classification of a single digital dental crown model, the fitting of a long shaft of the dental crown model, the determination of an impedance center, the design of tooth arrangement and the optimization and adjustment of a rotation center, the designed rotation center of the tooth is basically consistent with the rotation center in the actual correcting process, so that the treatment effect of the tooth accords with the expected effect, and the occurrence of medical accidents is further avoided.

Description

Rotation center design inspection method, shell-shaped dental instrument design and preparation method

Technical Field

The invention belongs to the technical field of tooth correction, and particularly relates to a shell-shaped tooth corrector manufacturing technology, in particular to a design and inspection method for a rotation center based on a digital dental crown model, a tooth arrangement method based on the digital dental crown model, a shell-shaped dental appliance design method and a shell-shaped dental appliance preparation method.

Background

In the process of designing orthodontic treatment, a single digital tooth model of a patient needs to be moved and arranged in a three-dimensional space, namely, the process of simulating digital tooth arrangement. However, in the current orthodontic treatment of teeth, actual intraoral information of a patient is converted into a digitized tooth three-dimensional model, then the digitized tooth three-dimensional model is segmented to obtain a digitized dental crown model, the surface of the digitized dental crown model is repaired to enable the shape of the repaired digitized dental crown model to be closer to the real tooth shape of the patient, then the digitized dental crown model is subjected to rotational translation operation to gradually change the arrangement mode to a target correction position, and finally a series of tooth correctors are manufactured according to each step of the gradually changed digitized dental crown model.

Because of different data acquisition modes, the digital tooth models are not provided with digital tooth root models, so that the rotation center of the digital tooth models can only be designed on the digital tooth crown models or the repaired digital tooth crown models, parameters of the digital tooth root models need to be simulated and estimated, and the accuracy of the mode has certain deviation, so that the actual corrected position of the teeth is probably not consistent with the expected target correction position in the actual correction process, the correction effect is not ideal for light persons, and the correction period is prolonged; even in severe cases, the tooth root is removed from the alveolar bone in the process of correcting the tooth, which causes serious medical accidents.

Therefore, the invention provides a corresponding technical scheme aiming at the problem that the selected rotation center is tested in the tooth arrangement designing process to ensure that the rotation center is closer to and better than the real intraoral condition of a patient.

Disclosure of Invention

The invention mainly aims to overcome the defects of the prior art, and provides a design inspection method for a rotary center based on a digital dental crown model, a tooth arrangement method based on the digital dental crown model, a shell-shaped dental appliance design method and a shell-shaped dental appliance preparation method, which solve the problem that the rotary center selected in the digital tooth arrangement process is deviated from the rotary center in the actual correction process.

The technical scheme provided by the invention is as follows:

the invention provides a design and inspection method for a rotation center based on a digital dental crown model, which comprises the following steps:

classification of single digital crown model: carrying out classification and labeling on the single digital dental crown model according to the classification standard of the standard digital dental crown model;

fitting of a long shaft of a single digital dental crown model: fitting a long axis of the single digital dental crown model based on the classified and labeled single digital dental crown model;

determination of the impedance center of the digital dental crown model: calculating the position of an impedance center point of the digital dental crown model based on the point of each point on the single digital dental crown model projected to the long axis and the classification marking information of the digital dental crown model;

simulating a digital dental crown model tooth arrangement design: simulating a digital dental crown model tooth arrangement design based on the initial position and the target correction position of the digital dental crown model, and calculating a single-step movement amount of the digital dental crown model, wherein the single-step movement amount comprises a translation amount and a rotation amount of the digital dental crown model, and the rotation amount is a pose change amount generated by the digital dental crown model with a rotation center as a rotation point;

optimizing and adjusting the rotation center: respectively superposing impedance center points corresponding to the initial position and the target position of the digital dental crown model based on the translation amount, and calculating the rotation amount of the digital dental crown model; the preset position of the center of rotation is then verified based on the ratio of the torque applied to the digital crown model to the balancing torque applied to the digital dental appliance and the amount of rotation design.

Further preferably, the classification method of the single digital dental crown model comprises the following steps:

acquiring a digital dental model: acquiring a digital dental model, wherein the digital dental model comprises a digital dental crown model;

segmenting the digital dental model: dividing the digital dental model into a single digital dental crown model and a digital gum model;

classification of single digital crown model: and carrying out classification labeling on the single digital dental crown model according to the classification standard of the standard digital dental crown model.

Further preferably, the method for fitting the long axis of the single digital dental crown model comprises the following steps:

repairing a single digital dental crown model: performing digital mesh repairing on two side surfaces of two adjacent single digital dental crown models in the near-far direction and the bottom surface close to the digital gum model after classification and marking, wherein the plane formed after the bottom surface digital mesh repairing is a gum line fitting plane;

fitting of a long shaft of a single digital dental crown model: fitting a long axis of the single digital crown model based on a normal vector of the gum line fitting plane.

Further preferably, the method for determining the impedance center of the digital dental crown model specifically comprises the following steps:

and calculating the height of the single digital dental crown model along the long axis direction based on the distance between the cusp of the single digital dental crown model and the projection point of the gum line fitting plane which is respectively mapped to the long axis, wherein the point which is mapped to the long axis by the gum line fitting plane is taken as a starting point, and the position which extends to the direction of the digital dental crown model by half of the height of the single digital dental crown model is taken as the position of an impedance center.

based on the distance between the apex of the single digital tooth model and the projection point of the gum line fitting plane which is respectively mapped to the long axis, the point which is mapped to the long axis by the gum line fitting plane is taken as the starting point, and the position which extends to the direction of the digital tooth root model by half of the distance is taken as the position of the impedance center.

Further preferably, the direction of the long axis is set to be directed by the digitized tooth root model to the digitized tooth crown model or by the digitized tooth crown model to the digitized tooth root model.

Further preferably, the ratio of the difference from the rotation center to the impedance center to the difference from the apical point to the impedance center is set to a predetermined range to determine the accuracy of the single step movement amount design of the digital crown model.

Further preferably, when the ratio of the difference between the rotation center and the impedance center to the difference between the apical point and the impedance center is greater than or equal to 0, the ratio of the moment generated by the digital crown model to the balance moment generated by the digital appliance is 1-Exp [ - (D-C)/(B-C) ] where C is the impedance center relative coordinate position, D is the rotation center relative coordinate position, and B is the apical point relative coordinate position.

Further preferably, when a ratio of a difference between the rotation center and the impedance center to a difference between the apical point and the impedance center is less than 0, a ratio of a moment generated by the digital crown model to a balance moment generated by the digital appliance is greater than 1.

Further preferably, a uniformity check is performed on the basis of a ratio of a moment generated by applying the pose change amount to the digital dental crown model and a balance moment generated by applying the pose change amount to the digital dental appliance in the analog-digital dental crown model arrangement design method, and a ratio of a moment generated by applying the standard digital dental crown model to the digital dental appliance when moving; if the two ratios are uniform, the adjustment of the rotation center is not needed; if the two ratios are not uniform, the rotation center needs to be adjusted until the two ratios are uniform.

Further preferably, the pose of the digital dental crown model changes to translation when the ratio of the moment generated by the standard digital dental crown model when moving and the balance moment generated by the standard digital dental crown model when moving and the balance moment generated by the standard digital dental crown model when moving is 1.

Further preferably, when the ratio of the moment generated by the standard digital dental crown model when moving and applied to the digital dental crown model to the balance moment generated by the standard digital dental crown model when moving and applied to the digital dental appliance is 0, or between 0 and 1, or greater than 1, the pose of the digital dental crown model changes to rotation.

Further preferably, the method of acquiring a digital dental model is intraoral scanning acquisition data or impression acquisition data.

Further preferably, the single digital crown model is classified and labeled by an FDI labeling method, a Parmer tooth position representation method or a general recording method.

Further preferably, the method for repairing the single digital dental crown model comprises the following steps:

dividing the digital dental crown model into a single digital dental crown model with a dividing boundary, wherein the dividing boundary comprises a dividing boundary between two adjacent digital dental crown models and a bottom surface dividing boundary close to the digital gingival model;

initial repairing of a segmentation boundary, namely performing initial repairing on the side surface in the near-far direction of two adjacent digital dental crown models so as to perform initial fitting on two adjacent surfaces between the two adjacent single digital dental crown models, wherein the segmentation boundary is completely repaired, and the single digital dental crown model is initially repaired near the bottom segmentation boundary of the digital gum model so as to completely repair the bottom segmentation boundary of the single digital dental crown model and obtain an initial repairing grid of the single digital dental crown model;

optimizing and adjusting the initialized repairing mesh, and performing optimizing and adjusting the preset distance between the vertexes of the initialized repairing mesh of two adjacent digital dental crown models by adopting a quadratic programming method so as to prevent two adjacent surfaces between the two adjacent digital dental crown models from colliding with each other; and simultaneously, initializing a repairing grid of the single digital dental crown model close to the bottom surface of the digital gum model for optimization and adjustment.

Further preferably, the initial repairing method of the segmentation boundary is to perform digital mesh repairing on the segmentation boundary by using a minimum angle method.

Further preferably, the method for optimally trimming the bottom surface of the single digital dental crown model adjacent to the digital gum model comprises a method for performing extension setting on the bottom surface of the initially trimmed digital dental crown model in the direction of the extension axis.

Further preferably, v is set in such a manner that the coordinates of the digital mesh vertexes of the bottom surface of the digital crown model extend in the tooth root direction along the tooth long axis direction by h_k＝v_k0+ h × m, wherein k ∈ digitizes the crown base part, wherein v_k0And (3) representing the coordinates of the vertex of the digital mesh after the initial trimming of the segmentation boundary of the bottom surface part of the digital dental crown, wherein h is the translation distance, and m is the direction of the dental axis.

The invention also provides a tooth arrangement method based on the digital dental crown model, which comprises the following steps: and performing tooth arrangement design of the digital dental crown model after the rotational center design inspection method based on the digital dental crown model is qualified.

The invention also provides a design method of the shell-shaped dental instrument, which comprises the following steps:

obtaining a digital dental crown model after tooth arrangement based on the tooth arrangement method based on the digital dental crown model;

design of shell-like dental instruments: designing a shell-shaped dental instrument having the digital dental crown model accommodated therein based on the arranged digital dental crown model, wherein the ratio of the moment generated by the shell-shaped dental instrument applied to the digital dental crown model to the balance moment generated by the digital dental crown model applied to the shell-shaped dental instrument is controlled within a predetermined value or range to adjust the pose change of the digital dental model.

The invention also provides a preparation method of the shell-shaped dental instrument, which is used for correspondingly preparing the designed shell-shaped dental instrument based on the design method of the shell-shaped dental instrument, and the specific preparation method comprises the following steps: 3D printing is carried out on the digital dental model after the pose change, a solid dental model is prepared, then shell-shaped dental appliances containing tooth shapes are obtained on the solid dental model in a hot press forming mode, and then the shell-shaped dental appliances containing the tooth shapes are obtained by cutting along a gum line or at a position close to the gum line on the shell-shaped dental appliances containing the tooth shapes.

The invention also provides a preparation method of the shell-shaped dental instrument, which is used for correspondingly preparing the designed shell-shaped dental instrument based on the design method of the shell-shaped dental instrument, and the specific preparation method comprises the following steps: and printing and preparing the designed shell-shaped dental instrument by adopting a direct 3D printing method.

According to the design and inspection method for the rotation center based on the digital dental crown model, the design and inspection of the rotation center of the digital dental crown model are carried out through the steps of classifying the single digital dental crown model, fitting the long shaft of the digital dental crown model, determining the impedance center, designing the tooth arrangement, optimizing and adjusting the rotation center and the like, the subsequent tooth arrangement design and the design and preparation of the shell-shaped dental appliance are carried out on the rotation center meeting the inspection requirement, the consistency of the rotation center designed aiming at the digital dental crown model and the actual correction process is ensured, and the tooth treatment effect is ensured to meet the expected target correction effect. Specifically, the impedance center of the digital dental crown model is determined only by adopting the digital dental crown model in the provided determination mode of the impedance center of the digital dental crown model, the intraoral collected data only contains intraoral information obtained by the digital dental crown model, the position of the impedance center of the individualized teeth of a patient can be accurately determined, then the digital dental crown model is simulated to perform tooth arrangement design, the tooth pose change is generated in the tooth arrangement design, the preset position of the rotation center is adjusted, the rotation center after the inspection is adjusted to accord with the optimal scheme of the tooth arrangement design, the subsequently prepared shell-shaped teeth correcting device can align the teeth of the patient to the target correcting position, and the phenomenon of bone windowing or bone cracking is avoided in the process of tooth movement.

Drawings

The foregoing features, technical features, advantages and embodiments are further described in the following detailed description of the preferred embodiments, which is to be read in connection with the accompanying drawings.

FIG. 1 is a flow chart of a design verification method for a rotational center based on a digital crown model according to the present invention;

FIG. 2 is a flowchart of a method for repairing a triangular mesh by a minimum inclusion angle method according to the present invention;

FIG. 3 is a schematic diagram of adding a triangular mesh patch;

FIG. 4 is a schematic diagram of adding two triangular mesh patches;

FIG. 5 is a flowchart illustrating optimization and adjustment of vertices of a mesh to be repaired according to the present invention;

FIG. 6 is a schematic diagram of the structure of a single digitized tooth model generated by the fitting of the present invention;

FIG. 7 is a flow chart of a digital crown model based tooth arrangement design provided by the present invention;

FIG. 8 is a flow chart of a shell-like dental instrument design provided by the present invention;

FIG. 9 is a flow chart illustrating the preparation of a shell-shaped dental instrument according to the present invention.

Detailed Description

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description will be made with reference to the accompanying drawings. It is obvious that the drawings in the following description are only some examples of the invention, and that for a person skilled in the art, other drawings and embodiments can be derived from them without inventive effort.

For the tooth correction of an orthodontic patient, the method that a doctor needs to align the teeth of the patient is that actual intraoral information of the patient is converted into a digital tooth three-dimensional model, then the digital tooth three-dimensional model is segmented to obtain a digital dental crown model, the surface of the digital dental crown model is repaired to enable the shape of the repaired digital dental crown model to be closer to the real tooth shape of the patient, then the digital dental crown model is rotated and translated to gradually change the arrangement mode to a target correction position, and finally a series of tooth correctors are manufactured according to each step of the digital dental crown model which gradually changes.

Aiming at the problems, the invention provides a corresponding solution, and the technical scheme provided by the invention solves the problem that the selected rotation center in the digital tooth arrangement process is deviated from the rotation center in the actual correction process. The technical scheme provided by the invention is as follows:

the first embodiment is as follows:

the embodiment provides a design verification method for a rotation center based on a digital dental crown model, and the flow chart is shown in fig. 1, and specifically comprises the following steps.

S110: classification of single digital crown models.

S120: and fitting the long axis of the single digital dental crown model.

S130: and (4) determining the impedance center of the digital crown model.

S140: and simulating the tooth arrangement design of the digital dental crown model.

S150: and optimally adjusting the rotation center.

The design inspection method of the rotation center solves the problem that the rotation center selected in the digital tooth arrangement process is deviated from the rotation center in the actual correction process. The above steps will be described in detail below.

Further, a specific implementation process of the step S110 will be described.

Because digital tooth arrangement is the operation of carrying out translation and rotation to single tooth, generally acquire digital tooth jaw model earlier, cut apart this digital tooth jaw model again, acquire each single tooth, then carry out digital tooth arrangement operation, need carry out sign or mark to single digital dental crown model before carrying out digital tooth arrangement operation. In this implementation, the single digital crown model is first classified in step S110.

In this embodiment, the acquired digital dental model includes a digital crown model, for example, data information of the digital dental model can be acquired by intraoral scanning, or data information of the digital dental model can be acquired by using an impression, and then the acquired data information is finally acquired by means of three-dimensional reconstruction.

The digitized dental model is then segmented using a segmentation technique, for example, the digitized dental model can be first segmented into a digitized dentition model and a digitized gingival model based on a gum line, and then the digitized dentition model can be segmented into individual digitized crown models using a region growing method. Besides the cutting method, a person skilled in the art can also segment the digital dental model into a single digital crown model and a digital gum model by other segmentation methods, for example, a seed diffusion method is adopted, and the present embodiment does not limit the specific segmentation method of the digital dental model, so long as the digital dental model is finally segmented into a single digital crown model and a digital gum model.

Because the intraoral condition of each orthodontic patient is diversified, that is, each different orthodontic patient has different initial tooth states, for different patients, the correction targets of the aligned dentition are different, the correction targets use the standard digital dental crown model as the reference standard, in the correction process, the standard digital dental crown model (which is a reference model common in the field of orthodontic teeth) is used as the reference standard, the orthodontic correction scheme matched with different deformed dentition is designed, and the deformed dentition can be arranged neatly through the orthodontic correction scheme.

In the process of correcting the teeth, in order to make the single digital dental crown model capable of referring to the corresponding standard digital dental crown model for performing the target correction, further, a mapping relationship between the single digital dental crown model and the corresponding standard digital dental crown model needs to be established, and specifically in this embodiment, the single digital dental crown model is classified and labeled according to the classification standard of the standard digital dental crown model.

For example, the single digitized crown model may be classified according to the classification criteria of the standard digitized crown model using FDI labeling, parmer tooth position representation, or general registration.

The FDI labeling method is used as an example to perform classification labeling on a single digital dental crown model, wherein the symbol of each tooth is two digits, the one digit represents a tooth area, and the ten digit represents a sequential number, for example, if a single digital dental crown model is labeled as 15, the single digital dental crown model corresponds to the second premolar on the right of the upper jaw in a standard digital dental crown model.

Further, a specific process of fitting the long axis of the single digital crown model in the step S120 is described.

As mentioned above, since the obtained single digital dental crown model does not have a tooth root, in the existing digital tooth arrangement, the setting position of the rotation center may be located on the digital dental crown model or not located on the digital dental crown model, so that the design basis and the design display in the design process are not clear, and the design deviation of the rotation center in the subsequent tooth arrangement process is large. In order to solve the problem, the embodiment performs long axis fitting on a single digital dental crown model, and then performs subsequent impedance center determination according to the long axis of the fitted digital dental crown model, wherein the impedance center determination provides a basis for the design of the subsequent rotation center. Different from the existing digital tooth arrangement, the embodiment creatively proposes to fit the digital dental crown model long shaft and then perform subsequent operations based on the fitted digital dental crown model long shaft, so as to enable the designed rotation center to be closer to the rotation center actually corrected by the patient.

In step S110, the single digital crown model is classified and labeled based on the classification standard of the standard digital crown model, and further, in this step, the long axis of the single digital crown model is fitted based on the classified and labeled single digital crown model. Step S120 specifically includes the following steps:

s121: and (5) repairing a single digital dental crown model.

And performing digital mesh repairing on two side surfaces of the two classified and labeled adjacent single digital dental crown models in the near-far direction and the bottom surface close to the digital gum model, wherein the plane formed after the digital mesh repairing of the bottom surface is a gum line fitting plane.

Before the single digital crown model is classified in step S110, the digital jaw model is divided to obtain the single digital crown model, and the divided single digital crown model has a dividing boundary including a dividing boundary between two adjacent single digital crown models, so that the dividing boundary between two adjacent single digital crown models needs to be repaired.

In this embodiment, the method for repairing the segmented boundary of the single digital dental crown model specifically includes the following steps:

s1211: initial patching of the segmentation boundary.

And performing initial repairing on the side surfaces of the two adjacent single digital dental crown models in the near-far direction so as to perform preliminary fitting on two adjacent surfaces between the two adjacent single digital dental crown models, and completely repairing the segmentation boundary to obtain an initial repairing grid of the single digital dental crown model.

The further understanding of the "mesial-distal direction of the digital crown model" is: "center" refers to the midline which is an imaginary vertical line bisecting the craniofacial area into left and right halves, the midline passing through the contact area between the left and right eyes, the tip of the nose, and the left and right incisors. The teeth are closer to the midline in the mesial direction, and vice versa in the distal direction.

In this embodiment, the digital mesh repairing is performed on the segmentation boundary by using a minimum angle method, which specifically includes: calculating the size of an included angle between two adjacent edges of each boundary point on the digital dental crown model; finding out boundary points with the minimum included angle, and judging the number of the increased digital triangular patches; increasing a corresponding number of digital triangular patches between the boundary points with the minimum included angle; and updating the boundary point information, and finding out the next boundary point with the minimum included angle until the segmented boundary repairing is finished.

S1212: and initializing the optimization adjustment of the repair grid.

And optimally adjusting the preset distance between the vertexes of the initialized repairing meshes of the two adjacent single digital crown models by adopting a quadratic programming method so as to prevent the two adjacent surfaces between the two adjacent single digital crown models from colliding with each other.

In order to avoid the mutual collision between the repaired adjacent surfaces, in step S1212, a quadratic programming method is used to perform an optimized adjustment of a predetermined distance between the vertices of the initialized repair mesh of the two adjacent digital dental crown models, where the predetermined distance is a distance maintained between the two adjacent digital dental crown models to avoid the collision, and the network vertices of the initialized repair mesh (i.e., the vertices of the mesh of the digital dental crown repair) are optimized and adjusted according to the predetermined distance, so that the two adjacent surfaces of the two adjacent digital dental crown models do not collide with each other. The quadratic programming is a special mathematical programming problem in nonlinear programming, and is applied in many aspects, such as solving of beam least square problem, application of sequential quadratic programming in nonlinear optimization problem, and the like.

S122: and performing long-axis fitting of the single digital dental crown model based on the repaired single digital dental crown model.

The initial repairing of the segmentation boundary of the single digital dental crown model and the optimization adjustment after the mesh initial repairing are completed through the steps S1211 and S1212, and the long axis fitting of the single digital dental crown model is performed on the basis.

In this embodiment, the long axis of the single digital dental crown model is fitted based on the normal vector of the gum line fitting plane, specifically, the long axis may be fitted with reference to a standard digital dental crown model, or an axis passing through the center of the digital dental crown model and parallel to the normal vector of the gum line fitting plane may be the long axis of the tooth according to the center position of the actual digital dental crown model. The center calculating method of the digital dental crown model is that the average coordinate point of each point coordinate on the digital dental crown model is the center position of the digital dental crown model.

The direction of the long axis may be from the digital tooth root model to the digital tooth crown model, or from the digital tooth crown model to the digital tooth root model, and the embodiment is not particularly limited.

The above steps S121 and S122 describe the implementation of the long-axis fitting process of the single digital crown model in step S120.

Further, a specific method of initially repairing the segmentation boundary by the minimum angle method in step S1211 will be described.

The specific method for performing digital mesh repairing on the segmentation boundary by the minimum angle method is shown in fig. 2, and specifically includes the following steps:

s210: and calculating the included angle of two adjacent edges of each boundary point on the digital dental crown model.

S220: and finding out the boundary point with the minimum included angle, and judging the number of the increased digital triangular patches.

The number of the increased digitized triangular patches can be judged in the following two ways.

One way is that: and calculating the distance s between two adjacent boundary points of the boundary point, judging whether the average side length s <2X is true, if so, adding one triangular patch, and if not, adding two triangular patches.

The other mode is as follows: and calculating the size theta of an included angle between two adjacent edges of the boundary point, judging whether theta is less than 120 degrees, if so, adding one triangular patch by the repairing method, and if not, adding two triangular patches by the repairing method.

The two repairing modes are based on the minimum included angle method to repair the lack part of the segmentation boundary, so that the repaired segmentation boundary has the effect of reality, nature and smoothness.

Taking the first way as an example, assuming that the average side length between adjacent boundary points in the digital crown model is L, if the boundary point a, the boundary point b and the boundary point c are boundary points on two adjacent sides, wherein the boundary point a is located between the boundary point b and the boundary point c, the side length L1 between the boundary point a and the boundary point b is calculated, the side length L02 between the boundary point a and the boundary point c is calculated, and then the sum of L1 and L2 is calculated, if (L1 + L2) < 2L is calculated, it is determined that the missing holes formed between the boundary point a, the boundary point b and the boundary point c are smaller, a triangle is added to the missing holes formed between the boundary point a, the boundary point b and the boundary point c, as shown in fig. 3, and if (L1 + L2) > 2L is calculated, it is determined that the boundary point a, the missing holes formed between the boundary point b and the boundary point c are larger, then the boundary point a boundary point b and the boundary point c are added to the missing holes formed as shown in the two triangle patch 4.

S230: and updating the boundary point information, and finding out the boundary point of the next minimum included angle until the completion of the segmentation boundary repair.

The digital mesh repairing of the segmentation boundary is completed through the steps S210-S230, and the repairing mode has the following effects: the number of reasonable digital triangular patches is increased to carry out digital mesh repairing, so that a real, natural and smooth single digital dental crown model can be obtained.

Because the digital dental crown model and the digital gum model are required to be segmented in the process of segmenting the digital teeth, incomplete places can also appear at the digital dental crown model close to the digital gum model after segmentation, the repairing method can simultaneously repair the side surface of the digital dental crown model in the near-far direction and the bottom surface close to the digital gum model side, the repairing of the digital dental crown model is more complete, and the efficiency is higher.

Further, the optimal adjustment of the predetermined distance between the vertices of the initialized mesh of the two adjacent single digital crown models by the quadratic programming method in step S1212 is described in detail.

Based on the basic idea of optimization and adjustment of the quadratic programming method, this embodiment provides two technical solutions of optimization and adjustment, where the first technical solution of optimization and adjustment is as follows, and its flowchart is shown in fig. 5.

S510: and fitting two side surfaces of two adjacent digital dental crown models in the near-far direction to form a dividing surface.

Preferably, the segmentation plane is fitted to a segmentation plane, for example, the segmentation plane is formed by fitting a set of intersection points of the near-far direction of two adjacent digital dental crown models by a point normal fitting method.

The point normal fitting method adopts a specific formula as shown in the following formula (1):

n·(x-o)＝0---(1)；

in formula (1), n is a normal vector of the division plane, o is a reference point on the division plane, and x is a set of points on the division plane.

S520: and maintaining the optimal adjustment of the preset distance from the mesh vertexes of two adjacent digital crown models to the distance between the segmentation surfaces.

If the distance d is kept between two adjacent digital dental crown models, mutual collision can be prevented, after a segmentation plane is formed by fitting according to the intersection point set of the two adjacent digital dental crown models in the near-far direction, the distance d/2 can be optimally adjusted by respectively keeping the distance between the mesh vertexes of the two adjacent digital dental crown models to the segmentation plane, and the purpose of preventing collision can be achieved.

In one embodiment, assuming that the expression of the splitting plane is ax + by + cz + d is 0 and the coordinates of the mesh vertex a of the adjacent digital dental crown model are (x1, y1, z1), the distance from the mesh vertex a to the splitting plane is calculated according to the point-to-plane distance calculation formula, the calculated distance is compared with the maintaining distance d/2, the coordinate position of the mesh vertex a is optimally adjusted according to the comparison result until the distance from the mesh vertex a to the splitting plane is the maintaining distance d/2, and the optimal adjustment of the mesh vertex a is finished.

The second optimization and adjustment technical scheme is as follows: the method for optimizing the objective function after setting the optimization constraint condition firstly carries out the optimization adjustment of maintaining the preset distance between the grid vertexes of two adjacent digital crown models of the initial repairing grid.

Wherein, optimizing the constraint condition setting comprises: keeping the coordinates of the digital mesh vertexes of the digital dental crown body part unchanged, extending the coordinates of the digital mesh vertexes of the digital dental crown bottom part along the long axis direction of the tooth to the digital tooth root direction, and keeping the distance d between two adjacent digital dental crown models.

The optimization constraints further include: keeping the coordinates of the digital grid vertexes of the digital dental crown body part unchanged, setting the following equation constraint condition:

v_j＝v_j0---(2)；

in equation (2), j ∈ digitizes the crown body portion area, where v_j0Original coordinates, v, representing the apex of the body region of the digital crown_jRepresenting optimized adjustments of the body region vertices of a digital crownThe latter coordinates;

keeping the distance d between two adjacent digital dental crown models, and setting the following inequality constraint conditions:

n·(v_i-o)-0.5·d≥0----(3)；

in the formula (3), d is a gap between the set adjacent digital dental crown models, d is more than or equal to 0, n is a normal vector of the segmentation plane, o is a reference point on the segmentation plane, and vi represents the vertex optimization coordinates of two adjacent teeth. And taking the distance from the mesh vertex closest to the segmentation plane in the single digital dental crown model to the segmentation plane as d/2, wherein the distance from the mesh vertex far away from the segmentation plane in the single digital dental crown model to the segmentation plane is larger than d/2, so that the distance between two adjacent digital dental crown models is kept as d.

The settings of the optimization objective function are:

in the formula (4), N represents the total number of vertexes of two adjacent teeth, and vi represents the vertex optimization coordinates of the two adjacent teeth.

And (4) calculating the objective function (4) according to the constraint conditions expressed by the formula (2) and the formula (3), and solving to obtain a mesh vertex which is the optimized and adjusted mesh vertex.

Further, in this embodiment, the bottom surface of the single digital dental crown model adjacent to the digital gum model is optimally adjusted by a predetermined distance by extending the initially repaired bottom surface of the digital dental crown model along the long axis direction of the tooth.

Specifically, the coordinates of the digital grid vertex of the bottom surface of the digital dental crown extend to the tooth root direction along the long axis direction of the tooth by h, and v is set_k＝v_k0+ h × m, where k ∈ digitizes the crown base, v_k0Coordinates of the vertices of the digitized mesh after initial trimming of the segmentation boundaries representing the bottom surface portion of the digitized crown, v_kThe coordinates of the vertexes of the digital mesh after the optimal adjustment of the segmentation boundary of the bottom surface part of the digital dental crown are expressed, and h is pre-The fixed translation distance (the range of h is 1mm-3mm, the value of h can be selected according to the actual condition), m is the unit quantity in the tooth axis direction, the tooth axis direction takes the direction of the dental crown pointing to the dental root as the positive direction, also can take the direction of the dental root pointing to the dental crown as the positive direction, and can be specifically selected according to the actual condition.

Through the steps S510-S520, the optimized adjustment of the preset distance is carried out between the initial repairing mesh vertexes of the two adjacent digital crown models obtained through initial repairing by adopting a quadratic programming method, so that two adjacent surfaces between the two adjacent digital crown models do not collide with each other.

Further, the determination process of the digital crown model impedance center in the above step S130 will be described.

And calculating the position of the impedance center point of the digital dental crown model based on the point projected to the long axis by each point on the single digital dental crown model and the classification marking information of the digital dental crown model.

Specifically, the long axis of the digital dental crown model is an axis passing through the center of the digital dental crown model, the axis is parallel to or coincident with a normal vector of a fitting plane of a gum line, each point on the digital dental crown model can project towards the long axis, at least 2 points are projected, namely a cusp point passing through the long axis, and a point comparing the fitting plane of the gum line with the long axis, the distance between the two points is the height of the single digital dental crown model from the gum line to the cusp direction, the height ratio of the height to the height corresponding to the standard digital dental crown model is utilized to simulate the digital dental root model, namely the actual dental root length of a patient is simulated according to the projection height corresponding to the standard digital dental root model along the long axis direction and the height ratio. For example, if the ratio of the height of the single digital crown model extending from the gum line to the cusp direction to the height of the standard digital crown model extending from the gum line to the cusp direction is 1.2:1, the length of the standard digital tooth root model in the long axis direction is increased by 1.2 times, the position of the cusp of the single digital tooth root model is further obtained, and the total length of the entire digital tooth model in the long axis direction is obtained by adding the height of the digital crown model from the gum line to the cusp direction and the height of the analog digital tooth root model.

The present embodiment provides the following two methods for determining the impedance center of the digital crown model.

One method is as follows: and calculating the height of the single digital dental crown model along the long axis direction based on the distance between the cusp and the gum line fitting plane of the single digital dental crown model and the projection points respectively mapped to the long axis, wherein the point mapped to the long axis by the gum line fitting plane is taken as a starting point, and the position extending to the digital dental crown model direction by half of the height of the single digital dental crown model is taken as the position of the impedance center.

The other method is as follows: firstly, a digital tooth root model is generated virtually: according to the single digital dental crown model after classification and marking, adopting a standard digital dental crown model to match and adjust to generate a digital dental root model, and fitting the digital dental crown model and the digital dental root model into the single digital dental model;

then, determining an impedance center based on the single digital tooth model: based on the distance between the apex of the root of a single digital tooth model and the projection point of the gum line fitting plane which is respectively mapped to the long axis, the point which is mapped to the long axis by the gum line fitting plane is taken as the starting point, and the position which extends half of the distance to the direction of the digital tooth root model is taken as the position of the impedance center.

Fig. 6 shows a schematic structural diagram of a single digital tooth model generated by fitting, in fig. 6, reference numeral 1 represents an initial single digital crown model, reference numeral 2 represents a mesh repairing part of a side surface of the single digital crown model in a near-far direction, a repaired digital crown model is formed by combination of the reference numerals 1 and 2, reference numeral 3 represents an analog digital tooth root model, reference numeral 4 represents an analog digital alveolar bone model, and the single digital tooth model with an alveolar bone is virtually simulated by the

reference numerals

1, 2, 3 and 4.

Point a in fig. 6 is a projection point of the gum line fitting plane mapped to the long axis, and may also be an intersection point of the digitized tooth root model and the digitized alveolar bone model in the long axis direction; and the point B is the position of the apex point of the digital tooth root model, the point A is taken as an initial point, the position extending to the direction of the digital tooth model by half of the distance AB is taken as a point C, and the point C is taken as the position of the impedance center.

Further, a specific process of the analog-digital crown model tooth arrangement design in the above step S140 will be described.

Simulating the tooth arrangement design of the digital dental crown model based on the initial position and the target correction position of the digital dental crown model, and calculating the single-step movement amount of the digital dental crown model, wherein the single-step movement amount comprises the translation amount and the rotation amount of the digital dental crown model, and the rotation amount is the pose change amount generated by the digital dental crown model by taking the rotation center as a rotation point.

The method is characterized in that the digital dental crown model is simulated to be designed in a tooth arrangement mode, the digital dental crown model is moved to a target correcting position from an initial position by moving the digital dental crown model, the movement comprises translation and rotation of the digital dental crown model, and the specific tooth arrangement design method needs to be designed in combination with the actual internal conditions of a patient.

Further, a specific procedure of the optimal adjustment of the rotation center in the above step S150 is described.

Respectively superposing impedance center points corresponding to the initial position and the target position of the digital dental crown model based on the translation amount, and calculating the rotation amount of the digital dental crown model; the design checks the preset position of the center of rotation based on the ratio of the torque applied to the digital crown model to the balancing torque applied to the digital dental appliance and the amount of rotation.

The optimum adjustment of the rotation center will be described in detail below.

First, biomechanics generated in tooth movement will be described.

The moving state of the teeth can be judged according to the relation of the ratio of the moment generated by being applied to the digital dental crown model and the balance moment generated by being applied to the digital dental appliance.

When the ratio of the moment generated on the digital crown model and the balance moment generated on the digital dental appliance is 0, the tooth rotates around the impedance center, in which case the rotation center and the impedance center substantially coincide;

when the ratio of the moment generated on the digital dental crown model to the balance moment generated on the digital dental appliance is between 0 and 1, the tooth root and the dental crown respectively move towards the same direction, and in this case, the rotation center shifts and gradually gets away from the impedance center;

when the ratio of the moment generated on the digital dental crown model to the balance moment generated on the digital dental appliance is 1, the tooth integrally translates, and in this case, the rotation center moves to infinity;

when the ratio of the moment generated on the digital crown model and the balancing moment generated on the digital dental appliance is greater than 1, the tooth root movement is greater than the crown movement, in which case the center of rotation is shifted to the incisal margin.

Once the impedance center position of the tooth is determined, the position is not changed, and only the position of the rotation center can be adjusted according to the actual situation, in this embodiment, after the digital dental crown model tooth arrangement design is simulated in step S140, whether the rotation center in the tooth arrangement process in step S140 meets the requirement is verified in step S150, in order to determine the accuracy of the single-step movement amount design of the digital dental crown model in step S140, the embodiment sets the ratio of the difference between the rotation center and the impedance center to the difference between the apical point and the impedance center within a predetermined range, so as to determine the accuracy of the single-step movement amount design of the digital dental crown model.

Wherein, the ratio of the difference value from the rotation center to the impedance center to the difference value from the root apex point to the impedance center and the ratio of the moment generated by being applied to the digital dental crown model to the balance moment generated by being applied to the digital dental appliance have the following mutual constraint relation:

specifically, when the ratio of the difference between the center of rotation and the center of impedance to the difference between the apical point and the center of impedance is greater than or equal to 0, the ratio of the moment generated by the digital crown model to the moment of balance generated by the digital dental appliance is 1-Exp [ - (D-C)/(B-C) ], where C is the relative coordinate position of the center of impedance, D is the relative coordinate position of the center of rotation, and D is away from the center of impedance C in the direction toward the root of the tooth, and B is the relative coordinate position of the apical point, where fig. 6 may be referred to for the specific positions of the relative coordinate position of the center of impedance C, the relative coordinate position of the apical point B, and the relative coordinate position of the center of rotation D.

That is, if it is judged that the ratio of the moment generated by being applied to the digital crown model to the balance moment generated by being applied to the digital dental appliance is 1-Exp [ - (D-C)/(B-C) ], it can be known that: the ratio of the difference from the rotation center to the impedance center to the difference from the apex point to the impedance center is 0 or more.

When the ratio of the difference from the center of rotation to the center of impedance to the difference from the apex to the center of impedance is less than 0, the ratio of the moment generated by the digital crown model to the balance moment generated by the digital appliance is greater than 1.

That is, when it is judged that the ratio of the moment generated by being applied to the digital crown model to the balance moment generated by being applied to the digital dental appliance is greater than 1, it can be known that: the ratio of the difference from the center of rotation to the center of impedance to the difference from the apex to the center of impedance is less than 0.

As can be seen from the above analysis, the ratio of the moment generated by applying the torque to the digital dental crown model to the balance moment generated by applying the torque to the digital dental appliance can directly determine the moving state of the tooth, and therefore, the present embodiment further checks whether the setting position of the rotation center meets the requirement by the moving state of the tooth (i.e., the pose variation in the tooth arrangement design).

In this embodiment, the rotation center in the tooth arrangement design is checked and adjusted according to a reference standard, which is a ratio of a moment generated by applying the standard digital dental crown model to the digital dental crown model when the standard digital dental crown model moves to a balance moment generated by applying the standard digital dental crown model to the digital dental appliance, and the specific checking and adjusting process is as follows:

carrying out uniformity inspection on the ratio of the moment generated by applying the model to the digital dental crown and the balance moment generated by applying the model to the digital dental appliance based on the pose variation in the analog digital dental crown model tooth arrangement design method, and the ratio of the moment generated by applying the model to the digital dental crown and the balance moment generated by applying the model to the digital dental appliance when the standard digital dental crown model moves; if the two ratios are uniform, the adjustment of the rotation center is not needed; if the two ratios are not uniform, the rotation center needs to be adjusted until the two ratios are uniform.

Because of the ratio of the difference from the center of rotation to the center of impedance to the difference from the apex to the center of impedance, to the ratio of the moment generated on the digital crown model to the moment of balance generated on the digital appliance, the two ratios have a mutually restricted relationship, so that the ratio of the torque generated by applying the digital dental crown model to the balance torque generated by applying the standard digital dental crown model to the digital dental appliance is unified with the ratio of the torque generated by applying the standard digital dental crown model to the balance torque generated by applying the standard digital dental crown model to the digital dental appliance, the essence of the process of unified adjustment is the process of adjusting the center of rotation, and by unifying the two ratios, the designed center of rotation is finally unified with the center of rotation when the standard digital dental crown model moves.

When the ratio of the moment generated by applying the standard digital dental crown model to the digital dental crown model when the standard digital dental crown model moves to the balance moment generated by applying the standard digital dental crown model to the digital dental appliance is 1, the pose change of the digital dental crown model is translation.

When the ratio of the moment generated by the standard digital dental crown model when moving and applied to the digital dental crown model to the balance moment generated by the standard digital dental crown model when moving is 0, or between 0 and 1, or more than 1, the pose of the digital dental crown model changes into rotation.

According to the design and inspection method for the rotation center based on the digital dental crown model, through the steps of classifying single digital dental crown model, fitting the long shaft of the digital dental crown model, determining the impedance center, designing the tooth arrangement, optimizing and adjusting the rotation center and the like, the design and inspection of the rotation center of the digital dental crown model are performed, the subsequent tooth arrangement design and the design and preparation of shell-shaped dental appliances are performed on the rotation center meeting the inspection requirements, the consistency of the rotation center designed aiming at the digital dental crown model and the actual correcting process is ensured, and the tooth treatment effect is ensured to meet the expected target correcting effect. Specifically, the impedance center of the digital dental crown model is determined only by adopting the digital dental crown model in the provided determination mode of the impedance center of the digital dental crown model, the intraoral collected data only contains intraoral information obtained by the digital dental crown model, the position of the impedance center of the individualized teeth of a patient can be accurately determined, then the digital dental crown model is simulated to perform tooth arrangement design, the tooth pose change is generated in the tooth arrangement design, the preset position of the rotation center is adjusted, the rotation center after the inspection is adjusted to accord with the optimal scheme of the tooth arrangement design, the subsequently prepared shell-shaped teeth correcting device can align the teeth of the patient to the target correcting position, and the phenomenon of bone windowing or bone cracking is avoided in the process of tooth movement.

Example two:

the present embodiment provides a tooth arrangement method based on a digital crown model, and a flowchart thereof is shown in fig. 7, which specifically includes the following steps.

S710: and acquiring the digital dental model.

The digital dental model comprises a digital dental crown model, for example, data information of the digital dental model can be acquired by adopting intraoral scanning, or data information of the digital dental model can be acquired by adopting an impression, and then the acquired data information is finally acquired by adopting a three-dimensional reconstruction mode.

S720: and (3) segmenting the digital dental model, and segmenting the digital dental model into a single digital dental crown model with a segmentation boundary.

The digitized dental model obtained in step S710 is segmented by a segmentation technique, for example, the digitized dental model can be first segmented into a digitized dentition model and a digitized gingival model based on a gum line, and then the digitized dentition model can be segmented into a single digitized crown model by an area growing method. Besides the cutting method, a person skilled in the art can also segment the digital dental model into a single digital crown model and a digital gum model by other segmentation methods, for example, a seed diffusion method is adopted, and the present embodiment does not limit the specific segmentation method of the digital dental model, so long as the digital dental model is finally segmented into a single digital crown model and a digital gum model.

S730: classification of single digital crown models.

S740: and fitting the long axis of the single digital dental crown model.

S750: and (4) determining the impedance center of the digital crown model.

S760: and simulating the tooth arrangement design of the digital dental crown model.

S770: and optimally adjusting the rotation center until the rotation center is qualified.

For the design check of the rotation center and the optimization adjustment process of the rotation center in the above steps S730 to S770, please refer to steps S110 to S150 in the first embodiment, which is not described in detail in this embodiment.

S780: and (4) performing tooth arrangement design of the digital dental crown model based on the qualified rotation center.

Specifically, according to correcting the target, rotate the qualified digital dental crown model of rotation center design inspection and rotate, the translation operation, will digitize the dental crown model and remove to correcting the target location by initial position, accomplish the process of arranging the tooth, and then design out a series of and remove gradually to correcting the digital dental crown model of target location by initial position.

According to the tooth arrangement method provided by the invention, in the process of designing and checking the rotation center and optimizing and adjusting the rotation center based on the digital dental crown model, the design and the check of the rotation center of the digital dental crown model are carried out through the steps of classifying single digital dental crown models, fitting the long shaft of the digital dental crown model, determining the impedance center, designing the arrangement of teeth, optimizing and adjusting the rotation center and the like, the design and the check of the rotation center of the digital dental crown model are carried out, the subsequent tooth arrangement design is carried out on the rotation center meeting the check requirement, the consistency of the rotation center designed aiming at the digital dental crown model and the actual correction process is ensured, and the tooth treatment effect is ensured to meet the expected target correction effect. Specifically, the impedance center of the digital dental crown model is determined only by the digital dental crown model in the provided determination mode of the impedance center of the digital dental crown model, the position of the impedance center of the personalized tooth of the patient can be accurately determined by only obtaining the intraoral information of the digital dental crown model from intraoral collected data, then the digital dental crown model is simulated to perform tooth arrangement design, the tooth pose change is generated in the tooth arrangement design, the preset position of the rotation center is adjusted, and the rotation center after the verification is adjusted to accord with the more optimal scheme of the tooth arrangement design.

According to the method for arranging the digital dental crown model, the obtained shell-shaped dental appliance is more suitable for the actual situation in the mouth of a patient, the situation that the digital dental crown model is arranged differently from the actual arrangement of the teeth of the patient due to the incompleteness of the digital dental crown model or the difference between the incompleteness and the situation in the mouth of the patient in the process of simulating tooth arrangement, collision between the teeth in the actual correction process occurs, and the subsequently prepared shell-shaped dental appliance can be more suitable for the correction target position of the patient in use.

Example three:

the present embodiment provides a method for designing a shell-shaped dental instrument, which specifically includes the following steps, and a flowchart thereof is shown in fig. 8.

S810: and acquiring the digital dental model.

S820: and (3) segmenting the digital dental model, and segmenting the digital dental model into a single digital dental crown model with a segmentation boundary.

For the implementation of the steps S810 and S820, please refer to the steps S710 and S720 in the second embodiment, which is not repeated herein.

S830: classification of single digital crown models.

S840: and fitting the long axis of the single digital dental crown model.

S850: and (4) determining the impedance center of the digital crown model.

S860: and simulating the tooth arrangement design of the digital dental crown model.

S870: and optimally adjusting the rotation center until the rotation center is qualified.

For the design check of the rotation center and the optimization adjustment process of the rotation center in the above steps S830 to S870, please refer to steps S110 to S150 in the first embodiment, which is not repeated herein.

S880: and (4) performing tooth arrangement design of the digital dental crown model based on the qualified rotation center to obtain the digital dental crown model after tooth arrangement.

Specifically, according to correcting the target, rotate, the translation operation is carried out to the qualified digital dental crown model of rotational center design inspection, will digitize the dental crown model and remove to correcting the target location by initial position, accomplish the tooth process of arranging, and then design out a series of and remove gradually to correcting the digital dental crown model of target location by initial position.

S890: design of shell-like dental instruments.

And designing a shell-shaped dental instrument for accommodating the digital dental crown model based on the digital dental crown model after tooth arrangement, wherein the ratio of the moment generated by applying the shell-shaped dental instrument to the digital dental crown model to the balance moment generated by applying the digital dental crown model to the shell-shaped dental instrument is controlled within a preset value or range so as to adjust the pose change of the digital dental model.

Specifically, the pose change of the digital tooth model can be adjusted by controlling the ratio to be within the following numerical value or range.

When the ratio of the moment generated by the shell-shaped dental instrument applied to the digital dental crown model to the balance moment generated by the digital dental crown model applied to the shell-shaped dental instrument is 1, the pose of the digital dental model changes into translation.

When the ratio of the moment generated by the shell-shaped dental instrument applied to the digital dental crown model to the balance moment generated by the digital dental crown model applied to the shell-shaped dental instrument is 0, or between 0 and 1, or greater than 1, the pose of the digital dental model changes into rotation.

The specific manner of designing the above shell-shaped dental instrument is described in example 1, and this embodiment is not described in detail.

According to the shell-shaped dental instrument design method provided by the embodiment, through the steps of classifying single digital dental crown models, fitting the long shafts of the digital dental crown models, determining impedance centers, designing tooth arrangement, optimizing and adjusting rotation centers and the like, the design and the inspection of the rotation centers of the digital dental crown models are carried out, the subsequent tooth arrangement design and the shell-shaped dental instrument design are carried out on the rotation centers meeting the inspection requirements, the consistency of the rotation centers designed aiming at the digital dental crown models and the actual correcting process is ensured, and the tooth treatment effect is ensured to meet the expected target correcting effect. Specifically, the impedance center of the digital dental crown model is determined only by adopting the digital dental crown model in the provided determination mode of the impedance center of the digital dental crown model, the intraoral collected data only contains intraoral information obtained by the digital dental crown model, the position of the impedance center of the individualized teeth of a patient can be accurately determined, then the digital dental crown model is simulated to perform tooth arrangement design, the tooth pose change is generated in the tooth arrangement design, the preset position of the rotation center is adjusted, the rotation center after the inspection is adjusted to accord with the optimal scheme of the tooth arrangement design, the subsequently prepared shell-shaped teeth correcting device can align the teeth of the patient to the target correcting position, and the phenomenon of bone windowing or bone cracking is avoided in the process of tooth movement.

Example four:

the present embodiment provides a method for manufacturing a shell-shaped dental instrument, which has a flowchart as shown in fig. 9 and specifically includes the following steps.

S910: and acquiring the digital dental model.

S920: and (3) segmenting the digital dental model, and segmenting the digital dental model into a single digital dental crown model with a segmentation boundary.

For the implementation of the steps S910 to S920, please refer to steps S710 and S720 in the second embodiment, which is not described in detail in this embodiment.

S930: classification of single digital crown models.

S940: and fitting the long axis of the single digital dental crown model.

S950: and (4) determining the impedance center of the digital crown model.

S960: and simulating the tooth arrangement design of the digital dental crown model.

S970: and optimally adjusting the rotation center until the rotation center is qualified.

For the design check of the rotation center and the optimization adjustment process of the rotation center in steps S930 to S970, reference is specifically made to steps S110 to S150 in the first embodiment, which is not repeated in this embodiment.

S980: and (4) performing tooth arrangement design of the digital dental crown model based on the qualified rotation center to obtain the digital dental crown model after tooth arrangement.

S990: design of shell-like dental instruments.

For the implementation of step S980 and step S990, reference is specifically made to step S880 and step S890 in the third embodiment, which is not described in detail in this embodiment.

S9100: 3D printing is carried out on the digital dental model of the shell-shaped dental instrument based on design, and the dental model of the entity is prepared.

S9110: and carrying out hot press molding on the solid dental model to obtain the shell-shaped dental appliance containing the tooth shape.

And pressing the membrane on the solid dental model by adopting a hot-pressing membrane forming process to obtain the shell-shaped dental appliance containing the tooth shape. The technology for preparing the shell-shaped dental instrument by the hot-pressing film forming process is a mature technology and is not described herein again.

S9120: cutting a shell-like dental appliance capable of receiving a tooth along or adjacent to the gum line on a shell-like dental appliance containing a tooth shape.

The shell-shaped dental instrument prepared in step S9110 is pressed on the dental model, and therefore, the shell-shaped dental instrument needs to be cut from the dental model by a cutting technique, for example, the cutting technique may be manual cutting, laser cutting, mechanical cutting, and the like, and the specific cutting manner is a relatively mature technique, which is not described herein again.

The shell-shaped dental appliance provided by the embodiment is prepared by a hot-pressing film forming process, and further, in addition to the hot-pressing film forming process, a person skilled in the art can prepare the shell-shaped dental appliance by other methods, for example, based on the shell-shaped dental appliance designed by the third embodiment, the shell-shaped dental appliance designed by the third embodiment is printed and prepared by a direct 3D printing method.

Further, in the shell-shaped dental appliance preparation method, according to the target correction effect and the actual oral problems of the patient, a model accessory with the correction function can be added to the digital dental crown model to design a series of digital dental crown models which enable the teeth to gradually move from the initial position to the target position, and then the shell-shaped dental appliance is designed, for example, the shell-shaped dental appliance can be specifically designed into a digital dental appliance main body or an entity dental appliance main body, wherein the digital shell-shaped dental appliance main body can be designed into a virtual digital shell-shaped dental appliance main body by using a finite element analysis method; the solid shell-shaped dental instrument main body can be used for designing an entity after the solid hot-press molding operation is carried out on the digital dental model, namely, the solid shell-shaped dental instrument main body is specially cut on the solid hot-press molded shell-shaped dental instrument.

Further, the shell-shaped dental instrument preparation method can be realized through a manufacturing module, and is 3D printing equipment, film pressing equipment, cutting equipment, polishing equipment and cleaning and disinfecting equipment.

According to the preparation method of the shell-shaped dental instrument, through the steps of classifying single digital dental crown models, fitting the long shafts of the digital dental crown models, determining impedance centers, designing tooth arrangement, optimizing and adjusting rotation centers and the like, the rotation centers of the digital dental crown models are subjected to design inspection, subsequent tooth arrangement design and shell-shaped dental instrument design and preparation are performed on the rotation centers meeting the inspection requirements, the consistency of the rotation centers designed aiming at the digital dental crown models and the actual correcting process is ensured, and the tooth treatment effect is ensured to meet the expected target correcting effect. Specifically, the impedance center of the digital dental crown model is determined only by adopting the digital dental crown model in the provided determination mode of the impedance center of the digital dental crown model, the intraoral collected data only contains intraoral information obtained by the digital dental crown model, the position of the impedance center of the individualized teeth of a patient can be accurately determined, then the digital dental crown model is simulated to perform tooth arrangement design, the tooth pose change is generated in the tooth arrangement design, the preset position of the rotation center is adjusted, the rotation center after the inspection is adjusted to accord with the optimal scheme of the tooth arrangement design, the subsequently prepared shell-shaped teeth correcting device can align the teeth of the patient to the target correcting position, and the phenomenon of bone windowing or bone cracking is avoided in the process of tooth movement.

It should be noted that the above embodiments can be freely combined as necessary. The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A design and inspection method for a rotation center based on a digital dental crown model is characterized by comprising the following steps:

2. The digital dental crown model based design verification of center of rotation method according to claim 1, wherein the classification method of the single digital dental crown model comprises:

3. The digital crown model rotation center based design verification method according to any one of the claims 1 or 2, wherein the fitting method of the single digital crown model long axis comprises:

repairing a single digital dental crown model: performing digital mesh repairing on two side surfaces of two adjacent single digital dental crown models in the near-far direction and the bottom surface close to the digital gum model after classification and marking, wherein a plane formed after the digital mesh repairing of the bottom surface is a gum line fitting plane;

4. The design verification method for rotation center based on digital dental crown model according to claim 3, characterized in that the determination method for impedance center of digital dental crown model comprises:

5. The digital dental crown model-based design verification of center of rotation method according to claim 3, further comprising the step of virtually generating a digital dental root model: and according to the single digital dental crown model after classification and marking, generating a digital dental root model by matching and adjusting with a standard digital dental crown model, and fitting the digital dental crown model and the digital dental root model into the single digital dental model.

6. The design verification method for rotation center based on digital dental crown model according to claim 5, characterized in that the determination method for impedance center of digital dental crown model comprises:

7. The digital dental crown model-based rotational center design verification method according to claim 6, wherein the direction of the long axis is set to be directed to the digital dental crown model by the digital dental root model or to be directed to the digital dental root model by the digital dental crown model.

8. The digital dental crown model-based design verification method for rotation center according to claim 7, wherein the ratio of the difference of the rotation center to the impedance center to the difference of the apical point to the impedance center is set to a predetermined range to determine the accuracy of one-step movement amount design of the digital dental crown model.

9. The method for designing and verifying the rotation center based on the digital dental crown model according to claim 8, wherein when the ratio of the difference from the rotation center to the impedance center to the difference from the apical point to the impedance center is 0 or more, the ratio of the moment generated by applying the digital dental crown model to the balance moment generated by applying the digital dental appliance is 1-Exp [ - (D-C)/(B-C) ], wherein C is the impedance center relative coordinate position, D is the rotation center relative coordinate position, and B is the apical point relative coordinate position.

10. The digital dental crown model-based design verification method for rotation center according to claim 8, wherein when the ratio of the difference from the rotation center to the impedance center to the difference from the apical point to the impedance center is less than 0, the ratio of the moment generated by the application to the digital dental crown model to the balance moment generated by the application to the digital dental appliance is more than 1.

11. The digital dental crown model-based rotation center design verification method according to any one of claims 8 to 10, wherein a ratio of a moment generated to be applied to the digital dental crown model and a balance moment generated to be applied to the digital dental appliance based on the pose change amount in the analog digital dental crown model tooth arrangement design method and a ratio of a moment generated to be applied to the digital dental appliance and a balance moment generated to be applied to the digital dental appliance generated when the standard digital dental crown model is moved are subjected to a uniformity test; if the two ratios are uniform, the adjustment of the rotation center is not needed; if the two ratios are not uniform, the rotation center needs to be adjusted until the two ratios are uniform.

12. The digital dental crown model-based design verification method for rotation center according to claim 11, wherein the pose change of the digital dental crown model is translation when the ratio of the moment generated by applying the standard digital dental crown model to the digital dental crown model generated by moving the standard digital dental crown model to the balance moment generated by applying the standard digital dental crown model to the digital dental appliance is 1.

13. The digital dental crown model-based design verification method for rotation center according to claim 11, wherein the pose of the digital dental crown model is changed to rotation when the ratio of the moment generated when the standard digital dental crown model is moved and applied to the digital dental crown model to the balance moment generated when the standard digital dental crown model is applied to the digital dental appliance is 0, or between 0 and 1, or greater than 1.

14. The digital crown model rotation center based design verification method according to claim 1, wherein the method for acquiring the digital dental model is intraoral scan acquisition data or impression acquisition data.

15. The digital dental crown model rotation center-based design inspection method according to claim 1, wherein the single digital dental crown model is classified and labeled by FDI labeling, Palmer tooth position representation or general registration.

16. The digital dental crown model rotation center-based design inspection method according to claim 3, wherein the single digital dental crown model has a segmentation boundary comprising a segmentation boundary between two adjacent single digital dental crown models and a bottom surface segmentation boundary adjacent to the digital gum model, the single digital dental crown model repairing method comprising:

17. The digital crown model-based design verification of rotation center according to claim 16, wherein the initial repairing of the segmentation boundary is a digital mesh repairing of the segmentation boundary using a minimum angle method.

18. The digital dental crown model rotation center based design verification method according to claim 16, wherein the method of optimally trimming the bottom surface of the single digital dental crown model adjacent to the digital gum model comprises a method of extending the bottom surface of the initially trimmed digital dental crown model in an extension axis direction.

19. The digital dental crown model-based design verification method for rotation center according to claim 16, wherein v is set for the coordinates of the digital mesh vertex of the bottom surface of the digital dental crown model extending from the long axis direction of the tooth to the root direction h_k＝v_k0+ h × m, wherein k ∈ digitizes the crown base part, wherein v_k0And (3) representing the coordinates of the vertex of the digital mesh after the initial trimming of the segmentation boundary of the bottom surface part of the digital dental crown, wherein h is the translation distance, and m is the direction of the dental axis.

20. A tooth arrangement method based on a digital dental crown model is characterized in that: performing a tooth arrangement design of the digital dental crown model after passing the verification of the rotational center design verification method based on the digital dental crown model according to any one of claims 1 to 19.

21. A method of designing a shell-like dental instrument, comprising:

obtaining a post-dentition digital crown model based on a method of dentition performed based on a digital crown model according to claim 20;

22. A method of making a shell-like dental instrument, comprising: the shell-shaped dental instrument designed according to the method for designing a shell-shaped dental instrument of claim 21 is manufactured accordingly, and the specific manufacturing method comprises the following steps: 3D printing is carried out on the digital dental model after the pose change, a solid dental model is prepared, then shell-shaped dental appliances containing tooth shapes are obtained on the solid dental model in a hot press forming mode, and then the shell-shaped dental appliances containing the tooth shapes are obtained by cutting along a gum line or at a position close to the gum line on the shell-shaped dental appliances containing the tooth shapes.

23. A method for manufacturing a shell-shaped dental instrument, wherein the designed shell-shaped dental instrument is manufactured based on the method for designing a shell-shaped dental instrument according to claim 21, and the method comprises: and printing and preparing the designed shell-shaped dental instrument by adopting a direct 3D printing method.