WO2021025296A1

WO2021025296A1 - Method for automatically recommending crown model and prosthesis cad apparatus for performing same

Info

Publication number: WO2021025296A1
Application number: PCT/KR2020/008553
Authority: WO
Inventors: 진방달; 문희철; 최규옥
Original assignee: 오스템임플란트 주식회사
Priority date: 2019-08-08
Filing date: 2020-07-01
Publication date: 2021-02-11
Also published as: KR102250520B1; KR20210018661A

Abstract

Disclosed are a method for automatically recommending a crown model and a prosthesis computer-aided design (CAD) apparatus for performing the same. A method for automatically recommending a crown model, according to one embodiment, automatically recommends a crown template model that best matches a target tooth requiring prosthetics through geometry modeling and image processing. Accordingly, a user may quickly and conveniently be recommended a crown having a similar shape to a tooth near the target tooth, and thus the time required for designing the crown can be reduced.

Description

Crown model automatic recommendation method and prosthetic CAD device performing the same

The present invention relates to a dental image processing technology, and more particularly, to a technology for designing a prosthesis.

In the dental field, prosthetic procedure refers to restoring a damaged tooth using a prosthesis. Prosthesis includes Crown, Inlay, Onlay, Coping, and Pontic. Before performing the actual prosthesis procedure, a virtual prosthesis suitable for the patient is selected through simulation, and the prosthesis is virtually placed at a target location. This process is performed through a prosthetic CAD (Computer Aided Design: CAD, hereinafter referred to as'CAD').

According to an embodiment, a method for automatically recommending a crown model that can minimize user manipulation and increase accuracy by automatically recommending an optimal prosthesis to a user when designing a prosthesis and a prosthetic CAD device for performing the same are proposed.

The method for automatically recommending a crown model according to an embodiment includes the steps of separating teeth from a dental image, and an analysis target corresponding to at least one of the same-name teeth, peripheral teeth, and opposing teeth in the dental image from which the teeth are separated. Extracting tooth features by analyzing a tooth image for each anterior or posterior tooth according to whether the tooth is an anterior or posterior tooth, comparing the tooth model from which the tooth feature is extracted with template models in the crown template list, and And recommending a crown template model from the crown template list by reflecting the tooth analysis and comparison results.

In the step of extracting tooth features, the tooth shape may be analyzed in the order of the same tooth, peripheral tooth, and opposing tooth of the target tooth.

In the step of extracting tooth features, if the tooth to be analyzed is an anterior tooth, extracting the boundary points of the front of the anterior tooth to analyze the pure surface shape, and the two points most distant from the horizontal direction of the anterior tooth among the boundary points and the vertical direction. The step of creating a bounding box with the three points including the highest point in, and extracting the shape features of the upper part of the anterior tooth using the ratio of the height and width of the created bounding box, and the furthest from the boundary points in the horizontal direction of the anterior tooth. It may include the step of generating a bounding box with two separated points and extracting a slope feature of the shape of the upper part of the anterior tooth using a ratio of the height and width of the generated bounding box.

In the step of extracting tooth features, if the tooth to be analyzed is an anterior tooth, extracting the boundary points of the front surface of the anterior tooth and the highest point in the vertical direction and the leftmost point in the horizontal direction of the anterior tooth among the boundary points. Separating the left or right boundary portion with a straight line connecting the lines, and extracting the shape features of the left or right boundary of the anterior teeth by obtaining the longest distance from the straight line among boundary points in the left or right boundary portion. have.

The step of extracting tooth features may include extracting boundary points of a side surface of the anterior tooth to analyze the degree of wear if the tooth to be analyzed is an anterior tooth, and extracting the wear characteristics of the anterior tooth from the extracted boundary points.

The step of extracting tooth features includes generating a curvature map of the posterior tooth if the tooth to be analyzed is a posterior region, and generating a bounding box consisting of four points furthest in the horizontal and vertical directions from the curvature map of the posterior tooth. And extracting a shape feature of an upper portion of the posterior tooth using a ratio of the height and width of the generated bounding box.

In the step of extracting tooth features, if the tooth to be analyzed is the posterior region, a bounding box consisting of points furthest in the vertical direction from the curvature map of the posterior tooth region is created, and using the created bounding box, the posterior tooth is inclined in the vertical direction visible from the upper surface. Including the step of extracting features, creating a bounding box consisting of points that are farthest in the horizontal direction from the curvature map of the posterior tooth, and extracting the horizontal tilt feature of the posterior tooth visible from the upper surface using the created bounding box. can do.

In the step of extracting tooth features, if the tooth to be analyzed is a posterior tooth, the convex point and the concave point may be separated from the curvature map of the posterior tooth, and a ratio of the number of convex points and the number of concave points may be extracted.

In the step of extracting tooth features, if the tooth to be analyzed is a posterior tooth, the curvature map of the posterior tooth is divided into a plurality of child boxes, and then the ratio features of the number of points of the child box, the number of convex points and the number of concave points of the child box are extracted. I can.

In the step of recommending a crown template model, if there is no crown template model desired by the user in the crown template model recommendation list, a new crown template model may be recommended after adjusting the weight of each feature manually or automatically.

In the prosthetic CAD device according to another embodiment, a data acquisition unit that acquires image data for prosthesis design, and extracts features of a tooth to be analyzed in the order of the same name, a peripheral value, and an opposing tooth of a target tooth requiring prosthesis from the image data. And a control unit that recommends a crown template model by reflecting the extracted tooth characteristics, and an output unit that displays information on the crown template model recommended by the control unit.

If the tooth to be analyzed is an anterior tooth, the control unit extracts boundary points of the front of the anterior tooth, and uses the extracted boundary points to at least one of the ratio of the height and width of the bounding box, the left boundary point of the anterior tooth-straight line distance, and the right boundary point of the anterior tooth-straight line distance. One can be quantified to extract features.

The control unit generates a curvature map of the posterior tooth if the tooth to be analyzed is a posterior region, extracts shape features of the upper part of the posterior tooth using the ratio of the height and width of the bounding box generated from the curvature map of the posterior tooth, and extracts the shape features of the upper part of the posterior tooth using the bounding box. It is possible to extract the vertical and horizontal inclination features of the teeth visible from the top surface.

The control unit generates a curvature map of the posterior region if the tooth to be analyzed is a posterior region, separates the convex point and the concave point from the curvature map of the posterior region, extracts the ratio of the number of convex points and the number of concave points, and calculates the curvature map of the posterior region. After dividing into a plurality of child boxes, the ratio features of the number of points of the child box, the number of convex points and the number of concave points of the child box can be extracted.

If there is no crown template model desired by the user in the crown template model recommendation list, the control unit may manually or automatically adjust the weight of each feature and recommend a new crown template model.

According to the method for automatically recommending a crown model and a prosthetic CAD device performing the same according to an embodiment, a crown template model that best matches a target tooth requiring prosthetics may be automatically recommended through geometric modeling and image processing. For example, using an algorithm that analyzes the shape of a tooth to be analyzed, such as the same tooth, peripheral tooth, and opposing tooth, for the target tooth, a crown template model that best matches the target tooth is recommended to the user. Accordingly, the user can quickly and conveniently receive recommendations for a crown having a shape similar to a tooth around the target tooth, thereby reducing crown design time.

Furthermore, by re-learning the final result selected by the user from among the recommended template models and reflecting the learning result in the recommendation, the more the user uses the system, the more accurately the user intends to recommend the template model close to the desired crown. It becomes more robust and more accurate.

1 is a diagram showing a process for a user to design a crown;

FIG. 2 is a diagram showing tooth model data including the same name teeth and peripheral values to be analyzed when designing the crown of FIG. 1;

FIG. 3 is a view showing tooth model data including opposing teeth to be analyzed when designing the crown of FIG. 1;

4 is a diagram showing a list of template models of crowns designed through the process of FIG. 1;

5 is a view showing the configuration of a prosthetic CAD device according to an embodiment of the present invention,

6 is a view showing the flow of the automatic crown recommendation method according to an embodiment of the present invention.

7 is a view showing an example of manual tooth separation through selection of feature points of teeth according to an embodiment of the present invention;

8 is a view showing an automatic tooth separation process according to an embodiment of the present invention;

9 is a diagram illustrating an example of extracting feature points of scan data according to an embodiment of the present invention;

10 is a diagram illustrating a process of calculating the dental arch line of FIG. 8 according to an embodiment of the present invention;

11 is a view showing input and output according to the tooth region separation process of FIG. 8 according to an embodiment of the present invention;

12 is a diagram illustrating characteristics of an anterior tooth extracted through a tooth feature analysis and comparison step of an anterior tooth according to an embodiment of the present invention;

13 is a view showing the ratio (3 points) of the height (Height) and the width (Width) of the AABB box of the anterior teeth according to an embodiment of the present invention;

14 is a view showing the ratio (2 points) of the height and width of the AABB box of the anterior tooth according to an embodiment of the present invention;

15 is a view showing a left boundary point-straight line distance of an anterior tooth according to an embodiment of the present invention;

16 is a diagram showing a right boundary point-straight line distance of an anterior tooth according to an embodiment of the present invention;

17 is a view showing a wear degree of an anterior tooth according to an embodiment of the present invention,

18 is a diagram showing an example of an anterior tooth recommendation result according to an embodiment of the present invention;

FIG. 19 is a diagram illustrating characteristics of a posterior tooth extracted through a tooth feature analysis and comparison step of a posterior tooth according to an embodiment of the present invention;

20 is a view showing a ratio (Height/Width) of the height and width of the AABB box of the posterior tooth according to an embodiment of the present invention;

21 is a ratio of the height and width of the AABB box of the posterior tooth portion (Height/Width) (vertical direction: Vertical) and the ratio of height and width (Height/Width) (horizontal direction: Horizontal) according to an embodiment of the present invention. Drawings,

22 is a view showing the ratio of the number of convex points and the number of concave points of the posterior tooth according to an embodiment of the present invention;

23 is a view showing the number of curvature points of a child box of a posterior tooth according to an embodiment of the present invention;

24 is a view showing a concave point ratio (Child Box Convex Concave points Ratio) of a child box of the posterior tooth according to an embodiment of the present invention.

25 is a view showing an example of a posterior tooth recommendation result according to an embodiment of the present invention;

26 is a diagram illustrating an example of a crown template recommendation scenario according to an embodiment of the present invention;

27 is a diagram showing an example in which a user corrects the weight of each feature according to an embodiment of the present invention;

28 is a diagram illustrating an example of automatically correcting the weight of each feature according to an embodiment of the present invention.

Advantages and features of the present invention, and a method of achieving them will become apparent with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in a variety of different forms, only the present embodiments are intended to complete the disclosure of the present invention, and the general knowledge in the technical field to which the present invention pertains. It is provided to completely inform the scope of the invention to those who have it, and the invention is only defined by the scope of the claims. The same reference numerals refer to the same components throughout the specification.

In describing embodiments of the present invention, if it is determined that a detailed description of a known function or configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted, and terms to be described later are in the embodiment of the present invention. These terms are defined in consideration of the function of the user and may vary according to the intention or custom of users or operators. Therefore, the definition should be made based on the contents throughout this specification.

Combinations of each block in the attached block diagram and each step in the flowchart may be executed by computer program instructions (execution engines), and these computer program instructions are provided on a processor of a general purpose computer, special purpose computer or other programmable data processing device. As it may be mounted, its instructions executed by the processor of a computer or other programmable data processing device generate means for performing the functions described in each block of the block diagram or each step of the flowchart.

These computer program instructions may also be stored in a computer usable or computer readable memory that can be directed to a computer or other programmable data processing device to implement a function in a particular way, so that the computer usable or computer readable memory It is also possible to produce an article of manufacture containing instruction means for performing the functions described in each block of the block diagram or each step of the flow chart.

In addition, since computer program instructions can be mounted on a computer or other programmable data processing device, a series of operation steps are performed on a computer or other programmable data processing device to create a computer-executable process. It is also possible for the instructions to perform the data processing apparatus to provide steps for executing the functions described in each block of the block diagram and each step of the flowchart.

In addition, each block or each step may represent a module, segment, or part of code containing one or more executable instructions for executing specified logical functions, and in some alternative embodiments mentioned in the blocks or steps. It should be noted that it is also possible for functions to occur out of order. For example, two blocks or steps shown in succession may in fact be performed substantially simultaneously, and the blocks or steps may be performed in the reverse order of a corresponding function as necessary.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the embodiments of the present invention exemplified below may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are provided to more completely describe the present invention to those of ordinary skill in the art to which this invention pertains.

1 to 4 are views showing examples of crown model design by a user.

In more detail, FIG. 1 is a diagram illustrating a process of designing a crown by a user, and FIG. 2 is a diagram illustrating tooth model data including the same name teeth and peripheral values to be analyzed during crown design of FIG. 1, and FIG. 3 FIG. 1 is a view showing tooth model data including opposing teeth to be analyzed during crown design of FIG. 1, and FIG. 4 is a diagram showing a list of template models of crowns designed through the process of FIG. 1.

Referring to FIG. 1, the user's crown design process through the prosthetic CAD program is that the user first selects a tooth model having a tooth shape similar to a target tooth that needs prosthesis, in the same order of the same tooth, peripheral tooth, and opposing tooth. Analyze the shape. To this end, if the crown template model list that has the same tooth number as the target tooth that needs prosthesis is listed in the prosthetic CAD program, the user selects the crown template model that is considered the most similar to the target tooth from the list. do. A template can also be called a library. The target is a damaged tooth that requires a prosthesis. The same tooth is the actual tooth located on the opposite side of the target tooth. The opposite side means that when the target tooth is on the left side of the maxilla, the upper jaw is a right position symmetrical to it with respect to the midline, and when the target tooth is on the right side of the mandible, the left mandible is symmetrical with it based on the midline. For example, in the case of the dental implant number divided into 4 teeth based on the midline and classified into 10th, 20th, 30th, and 40th teeth, the target value of the 33rd tooth is the 43rd tooth. Peripheral teeth are actual teeth located on the left and right of the target teeth. The antagonist tooth is an actual tooth positioned on the upper or lower side in antagonistic relationship with the target tooth.

As shown in FIG. 2, the teeth most similar to the target teeth requiring prosthetics are the same teeth, and are the teeth to be considered first. In situations where the same value cannot be considered, the peripheral value of the target tooth requiring prosthesis is considered.

When it is difficult to select a tooth similar to the target tooth from the same tooth and the peripheral tooth, the user may consider the opposing tooth of the target tooth as shown in FIG. 3. The user predicts the shape of the target tooth that needs prosthesis and compares the crown template model shape suggested by the prosthetic CAD program one by one as shown in FIG. 4, and finally, the tooth crown model that is considered to be the most similar to the target tooth that needs prosthesis. Choose

The crown model design process by the user described above with reference to FIGS. 1 to 4 may cause the following problems. Since each person has a different tooth shape, a variety of crown templates should be provided. Currently commercially available CAD programs for prosthesis prepare various lists of template models of these crowns in advance and show them to the user, and the user directly selects the desired template shape from the list. It takes a lot of time and effort to select the teeth most similar to the target teeth that need prosthetics from the list of templates in such a large quantity and variety. The variety of forms of the provided crown template model may cause inconvenience in the process of manually selecting a crown model while a user directly compares the same teeth, peripheral teeth, and opposing teeth.

5 is a view showing the configuration of a prosthetic CAD device according to an embodiment of the present invention.

Referring to FIG. 5, the prosthetic CAD device 1 performs a CAD process in order to help dental prosthesis in an actual dentistry. The prosthetic CAD process refers to a series of processes in which 3D tooth data of a patient is acquired, a virtual prosthetic model is retrieved from a library through control by a computer program, and then virtually placed at a target position of the tooth data. The 3D tooth data is data having 3D information on teeth including the damaged target tooth.

The prosthetic CAD device 1 is an electronic device capable of executing a dental program such as a prosthetic CAD program. Electronic devices include computers, notebook computers, laptop computers, tablet PCs, smartphones, mobile phones, personal media players (PMPs), personal digital assistants (PDAs), and the like. In addition to the prosthetic CAD program, the dental program includes a guide program, a scanning program, and a medical image processing program. In addition, it can be applied to other general medical programs in addition to dental prosthetic surgery.

Hereinafter, the configuration of the prosthetic CAD device 1 having the above-described features will be described later with reference to FIG. 5.

Referring to FIG. 5, a prosthetic CAD device 1 according to an embodiment includes a data acquisition unit 10, a storage unit 12, a control unit 14, an input unit 16, and an output unit 18.

The data acquisition unit 10 acquires dental image data from a patient. Dental image data required for prosthetic surgery include CT data and oral model data. The data acquisition unit 10 may execute CT data and oral model data in a program or load data stored in a web page and a server.

The oral model data is data with information on actual teeth including damaged teeth. The oral model data may be obtained by scanning a plaster model created after a patient's mouth with a 3D scanner. As another example, it may be obtained by scanning the inside of the patient's oral cavity using a 3D intra-oral scanner. The obtained oral model data may be stored in the storage unit 12.

CT data may be obtained by generating a patient's head tomography images using CT (Computed Tomography, computed tomography), segmenting the boundary of the tooth from each tomography image, and then combining them into one. These oral model data and CT data are images obtained by photographing the maxillary teeth under the maxillary teeth with the patient's mouth open, the images obtained by photographing the mandibular teeth above the mandibular teeth with the mouth open, and the local area with the mouth closed. Includes images obtained, oral radiographs, etc. The acquired CT data may be stored in the storage unit 12.

The storage unit 12 stores various types of data such as information necessary for performing an operation of the prosthetic CAD device 1 and information generated according to the operation. In the storage unit 12 according to an embodiment, oral model data and CT data of an individual patient are stored, and user request for oral model data and CT data of a specific patient among all oral model data and CT data during dental treatment simulation. It can be provided to the control unit 14 according to. At this time, the storage unit 12 stores images of the upper and lower teeth of an individual patient, and images of the upper and lower teeth that match the oral model data and CT data of a specific patient are stored at the user request. Accordingly, it can be provided to the control unit 14. In addition, the storage unit 12 may have a prosthetic template list composed of a plurality of prosthetic model data, and provide the prosthetic template list to the control unit 14.

The control unit 14 controls each component while establishing a prosthetic surgery plan through control by a computer program. The controller 14 manages screen information displayed on the screen through the output unit 18, and performs a simulation of placing a virtual prosthesis object in a medical image. A medical image in which a virtual object is placed refers to a multidimensional image, such as 2D or 3D, showing the patient's tooth arrangement created to establish a prosthetic surgery plan. Various types of images, such as X-ray, CT, panoramic images, oral scan images, images generated through reconstruction, and images that match multiple images, can be used for prosthetic surgery planning.

The control unit 14 according to an embodiment analyzes the tooth to be analyzed, such as the same tooth, peripheral tooth, and antagonist tooth, of the target tooth requiring prosthetics so that the user can minimize the operation of selecting the crown, and then analyzes it from the template list of the crown. The crown template model most similar to the target tooth is automatically recommended. In this case, the control unit 14 may extract features of the tooth to be analyzed in the order of the same name value, peripheral value, and opposing tooth of the target tooth requiring prosthetics, and may recommend the crown template model by reflecting the extracted tooth characteristics.

The control unit 14 may change the feature extraction method according to whether the tooth to be analyzed is an anterior or posterior tooth. The anterior and posterior teeth have different anatomical positions. According to the anatomical position, the incisors refer to a total of six teeth, three on each side, and a total of six teeth on the left and right based on the canonical line. Molar refers to the teeth (premolar and molars) behind the anterior teeth. The anterior and posterior teeth have different morphological features. According to the morphological characteristics, it is possible to distinguish anterior and posterior teeth by looking at the shape of the crown. The anterior teeth do not have a cusps and have a cut or apex. And Guchi has a cusp. In addition, anterior and posterior teeth can be distinguished by looking at the area of the occlusal surface of the opposing tooth.

Feature extraction method when the tooth to be analyzed is an anterior tooth For example, the control unit 14 extracts boundary points of the front surface of the anterior tooth and uses the extracted boundary points to determine the ratio of the height and width of the bounding box, and the left boundary point of the anterior tooth-a straight line. A feature is extracted by quantifying at least one of the distance and the right boundary point-straight line distance of the anterior tooth.

Feature extraction method when the analysis target tooth is a posterior tooth.For example, the control unit 14 generates a curvature map of the posterior tooth when the analysis target tooth is a posterior tooth, and calculates the ratio of the height and width of the bounding box generated from the curvature map of the posterior tooth. It can be used to extract the shape features of the upper part of the posterior teeth. In addition, by using the bounding box, the vertical and horizontal inclination features of the posterior teeth visible from the upper surface can be extracted.

As another example, when the tooth to be analyzed is a posterior tooth, the controller 14 may extract a ratio of the number of convex points and the number of concave points after separating the convex point and the concave point from the curvature map of the posterior tooth. In addition, after dividing the curvature map of the posterior tooth into a plurality of child boxes, the ratio features of the number of points of the child box and the number of convex points and the number of concave points of the child box can be extracted.

When there is no crown template model desired by the user in the crown template model recommendation list, the controller 14 may manually or automatically adjust the weight of each feature and recommend a new crown template model.

The output unit 18 displays the image data on a screen. In this case, the output unit 18 may display a simulation in which a virtual object is placed at an insertion position of the image data before performing an actual prosthetic treatment procedure. The output unit 18 may display crown template model recommendation information generated by the control unit 14 on the screen.

The input unit 16 receives a user manipulation signal. For example, a user operation for adjusting the ratio of each feature is input.

6 is a diagram illustrating a flow of a method for automatically recommending a crown according to an embodiment of the present invention.

Referring to FIG. 6, the prosthetic CAD device analyzes the target teeth, such as the same name, peripheral teeth, and opposing teeth, of the target tooth so that the user can minimize the selection of the crown, and We propose a technique that automatically recommends the most similar crown template model. To this end, the automatic crown recommendation method includes a tooth separation step (S610), a tooth feature extraction step (S620), a tooth model comparison step (S630), and a crown template recommendation step (S640).

The tooth separation step S610 includes manual tooth separation by user input and automatic tooth separation without user input. In the user's point of view, if the tooth is manually separated, the process is complicated and takes a long time, whereas the automatic tooth separation has the advantage that the process is easy and the operation is quick.

In the tooth feature extraction step (S620), the prosthetic CAD device is the anterior tooth according to whether the tooth to be analyzed corresponding to at least one of the same tooth, peripheral tooth, and opposing tooth in the dental image from which the teeth are separated is an anterior or posterior tooth. Alternatively, tooth features are extracted by analyzing tooth images for each posterior tooth. At this time, the tooth shape of the target tooth may be analyzed in the order of the same tooth, peripheral tooth, and opposing tooth.

When the tooth to be analyzed is the anterior tooth in the tooth feature extraction step S620, the prosthetic CAD device may extract boundary points of the front surface of the anterior tooth to analyze the pure surface shape. And among the boundary points, a bounding box is created with two points that are farthest in the horizontal direction of the anterior part and three points including the highest point in the vertical direction, and the anterior part is made using the ratio of the height and width of the created bounding box. The shape features of the upper part can be extracted. In addition, a bounding box may be generated from two points that are farthest from the horizontal direction of the anterior tooth among the boundary points, and the inclination feature of the upper part of the anterior tooth shape may be extracted using the ratio of the height and width of the generated bounding box.

As another example, when the tooth to be analyzed is an anterior tooth, the prosthetic CAD device extracts boundary points of the front surface of the anterior tooth to analyze the pure surface shape. Then, among the boundary points, the left or right boundary is separated by a straight line connecting the leftmost point in the horizontal direction of the anterior and the highest point in the vertical direction. In addition, shape features of the left or right boundary of the anterior tooth can be extracted by obtaining the longest distance from the straight line among boundary points on the left or right boundary. Furthermore, the boundary points of the side of the anterior tooth may be extracted, and the wear characteristics of the anterior tooth may be extracted from the extracted boundary points.

If the tooth to be analyzed is the posterior tooth in the tooth feature extraction step (S620), the prosthetic CAD device generates a curvature map of the posterior tooth. Subsequently, in the curvature map of the posterior tooth, a bounding box consisting of four points farthest in the horizontal and vertical directions is created. In addition, shape features of the upper part of the posterior tooth may be extracted using the ratio of the height and width of the generated bounding box.

As another example, if the tooth to be analyzed is the posterior part, a bounding box consisting of points that are farthest in the vertical direction from the curvature map of the posterior tooth part is created, and the vertical tilt feature of the posterior tooth seen from the upper surface can be extracted using the created bounding box. have. In the curvature map of the posterior tooth, a bounding box composed of points that are farthest in the horizontal direction can be created, and the horizontal tilt feature of the posterior tooth visible from the upper surface can be extracted using the generated bounding box. In addition, the convex point and the concave point can be separated from the curvature map of the posterior tooth, and the ratio of the number of convex points and the number of concave points can be extracted.

As another example, if the tooth to be analyzed is the posterior tooth, the curvature map of the posterior tooth may be divided into a plurality of child boxes, and then a ratio feature of the number of points of the child box and the number of convex points and the number of concave points of the child box may be extracted.

Subsequently, the prosthetic CAD device compares the tooth model from which the tooth feature is extracted with the template models in the crown template list (S630). In addition, the crown template model is recommended from the crown template list by reflecting the tooth analysis and comparison results (S640). In this case, a plurality of crown template models may be recommended, and crown templates may be recommended according to the ranking by assigning a ranking. Furthermore, when there is no crown template model desired by the user in the crown template model recommendation list, a new crown template model may be recommended after adjusting the weight of each feature manually or automatically.

7 is a diagram illustrating an example of manual tooth separation through selection of feature points of a tooth according to an embodiment of the present invention.

Referring to FIG. 7, when a user clicks two end points on one tooth with a mouse, the prosthetic CAD device uses an algorithm such as Dijkstra and Geometric Snake to connect the points with the largest curvature among the closed curves connecting the two points. To separate the teeth and gums.

8 is a diagram illustrating an automatic tooth separation process according to an embodiment of the present invention.

Referring to FIG. 8, the automatic tooth separation consists of a total of 4 steps, including a feature point extraction step of scan data (S810), a dental arch calculation step (S820), a feature point grouping step (S830), and a tooth region separation step (S840). Can be.

The feature point extraction step S810 is a step of finding points corresponding to tooth edges of the scan data. These points are poles that rise higher than the surrounding area when the teeth of the scan data are viewed from the occlusal plane direction. Watershed algorithms can be used to find this pole. A method of extracting feature points of scan data using a watershed algorithm will be described later with reference to FIG. 9. The dental arch calculation step (S820) will be described later with reference to FIG. 10. The feature point grouping step (S830) and the tooth region separation step (S840) will be described later with reference to FIG. 11.

9 is a diagram illustrating an example of extracting feature points from scan data according to an embodiment of the present invention.

Referring to FIG. 9, the prosthetic CAD device according to an embodiment extracts feature points of scan data using an image processing algorithm such as a watershed algorithm. The watershed algorithm records the number of samples starting from one vertex on the tooth data and moving along the edge in the occlusal surface to reach the floor, just as the valley water accumulates when water flows from a high place. It is an algorithm that selects valleys with fields as feature points.

10 is a diagram illustrating a process of calculating a dental arch line of FIG. 8 according to an embodiment of the present invention.

Referring to FIG. 10, the prosthetic CAD device may calculate a dental arch using an image-based algorithm. For example, a dental arch line may be obtained by extracting the feature points of the dentition region and connecting the extracted feature points. As the feature point, a feature point obtained with reference to FIG. 9 may be used.

The feature points obtained in the feature point extraction step (S810 in FIG. 8) are data in which the boundary of the tooth is not separated. In order to separate the tooth area later, these feature points must be separated for each tooth. The prosthetic CAD device according to an embodiment uses the Inspection Spoke algorithm to separate feature points. Inspection Spoke is a method of measuring the highest value by measuring the height of the tooth mesh data along a straight line passing through a point on the dental arch.

11 is a diagram illustrating inputs and outputs according to the process of separating a tooth region of FIG. 8 according to an embodiment of the present invention.

Referring to FIG. 11, in the step of extracting a tooth region, an individual tooth region may be identified using a harmonic field algorithm. The harmonic field is defined as a scalar field that satisfies the Poisson equation Δf = 0. When no condition is given, the solution to this equation becomes a constant function or a periodic function. Here, if a non-zero value is set as a conditional value at a specific point, an approximate solution can be used for various applications even if an exact solution does not exist. The approximate solution is generally a field that connects the condition values smoothly. In tooth region extraction, a scalar field is calculated from a vertex on the mesh data. At this time, condition values are set at each of the feature points within one group, the feature points of the other group, and the outer boundary points of the input mesh data so that the tooth region can be identified. With the condition values set in this way, the tooth area is extracted by obtaining an approximate solution of Δf = 0.

It is possible to separate the teeth and the gums from the scan data by using the manual and automatic methods as described above with reference to FIGS. 7 to 11. If the location of the target tooth for crown design work can be known in three dimensions, it can be used to design the crown by acquiring information on peripheral teeth, opposing teeth, and equal teeth from the separated teeth. The prosthetic CAD device according to an embodiment performs a process of analyzing and comparing tooth characteristics after tooth separation. In this case, different tooth features and comparison processes may be performed depending on whether the tooth to be analyzed is an anterior or posterior tooth.

Hereinafter, a tooth feature analysis and comparison process for an anterior tooth portion will be described later with reference to FIGS. 12 to 18, and a tooth feature analysis and comparison process for a posterior tooth portion will be described later with reference to FIGS. 19 to 25.

12 is a diagram illustrating characteristics of an anterior tooth extracted through a tooth feature analysis and comparison step of an anterior tooth according to an embodiment of the present invention.

Human teeth can be largely divided into anterior and posterior parts. Therefore, the algorithm for analyzing and comparing the tooth shape can be divided into anterior and posterior teeth. In FIG. 12, features of the anterior teeth are listed in detail. In order to extract the tooth features of the anterior teeth, the feature points may be acquired twice. First, the boundary points of the front of the anterior teeth are extracted to analyze the pure surface shape. Second, to analyze the degree of wear, the boundary points of the side of the anterior teeth are extracted.

After obtaining the labial boundary points, the following four anterior features can be defined, and each feature can be quantified and analyzed. The four features are Feature 1: The ratio of the height and width of the AABB box (Height / Width: 3 points) (see Fig. 13), Feature 2: The ratio of the height and width of the AABB box (2 points) (see Fig. 14), Feature 3: Includes Left Corner Point-Line Distance (See Fig. 15), Feature 4: Right Corner Point-Line Distance (See Fig. 16) . AABB box (Axis Aligned Bounding Box) is a kind of bounding box (Bounding Box).

13 is a diagram showing a ratio (3 points) of a height and a width of an AABB box of an anterior tooth according to an embodiment of the present invention.

Referring to FIG. 13, in order to determine the shape of the upper part of the anterior tooth, the prosthetic CAD device has two points farthest in the horizontal direction and the highest point in the vertical direction. This creates an AABB box with 3 dots. The shape of the upper part of the anterior tooth can be determined by using the ratio of the height and width of this AABB box (Height / Width: 3 points).

14 is a view showing the ratio (2 points) of the height and width of the AABB box of the anterior teeth according to an embodiment of the present invention.

Referring to FIG. 14, the prosthetic CAD device may generate an AABB box with two points farthest in the horizontal direction in order to determine the inclination of the upper part of the anterior tooth. Using the ratio of the height and width (Height / Width: 2 points) of this AABB box, the inclination of the shape of the upper part of the anterior tooth can be determined.

15 is a diagram showing a left boundary point-straight line distance of an anterior tooth according to an embodiment of the present invention.

Referring to FIG. 15, when determining the shape of the anterior tooth, the boundary shape is also one of the important judgment conditions. To this end, the left boundary portion can be separated by a straight line connecting the leftmost point in the horizontal direction and the highest point in the vertical direction. Among the boundary points on the left boundary, the longest distance to this straight line is obtained and normalized to determine the left boundary shape through the final value.

16 is a diagram illustrating a right boundary point-straight line distance of an anterior tooth according to an embodiment of the present invention.

Referring to FIG. 16, in order to determine the shape of the right boundary, the right boundary portion may be separated by a straight line connecting the rightmost point in the horizontal direction of the anterior teeth and the highest point in the vertical direction. The shape of the right boundary can be determined by obtaining and normalizing the longest distance to this straight line among boundary points on the right boundary.

17 is a view showing a wear degree of an anterior tooth according to an embodiment of the present invention.

Referring to FIG. 17, side boundary points are obtained in order to calculate the anterior tooth wear. Further, it is possible to calculate the degree of wear using tooth axis information and wear edge information.

18 is a diagram illustrating an example of an anterior tooth recommendation result according to an embodiment of the present invention.

The anterior teeth recommendation results obtained through the analysis of the five characteristics of the anterior teeth described above with reference to FIGS. 12 to 17 are as shown in FIG. 18. As shown in FIG. 18, a recommendation result may be provided in the form of a recommendation list. At this time, it is possible to provide a list of recommendations in order by assigning a ranking.

FIG. 19 is a diagram illustrating features of a posterior tooth extracted through a tooth feature analysis and comparison step of a posterior tooth according to an embodiment of the present invention.

Referring to FIG. 19, when analyzing the shape of the posterior part, the occlusal surface angle and wear degree are the most influential parts. Both occlusal angle and wear can be judged by curvature. In order to analyze the shape of the posterior tooth differently from the method of obtaining the boundary point at the anterior tooth, a curvature map may be generated using a curvature value. The curvature map will be described later with reference to FIG. 20.

After collecting the curvature map of the posterior tooth, the prosthetic CAD device can analyze the shape of the posterior tooth by defining six features and quantifying each feature. The six features are, Feature1: the ratio of the height and width of the AABB box (Height/Width) (see Fig. 20), Feature2: the ratio of the height and width of the AABB box in the vertical direction (Height/Width: Vertical) (see Fig. 21). ), Feature3: The ratio of the height and width of the AABB box in the horizontal direction (Height/Width: Horizontal) (see Fig. 21), Feature4: The ratio of the number of convex points and the number of concave points in the posterior teeth (Convex points Number/ Concave points Number) (See Fig. 22), Feature5: Child Box's point number (see Fig. 23), Feature6: Child Box Convex Concave points Ratio (Fig. 24) Reference).

20 is a diagram illustrating a ratio (Height/Width) of a height and a width of an AABB box of a posterior tooth according to an embodiment of the present invention.

Referring to FIG. 20, in the curvature map of the posterior tooth, an AABB box consisting of four points furthest in the horizontal and vertical directions may be generated. Using the AABB box created in this way, it is possible to determine the shape of the posterior teeth visible from the upper surface.

21 is a ratio of the height and width of the AABB box of the posterior tooth portion (Height/Width) (vertical direction: Vertical) and the ratio of height and width (Height/Width) (horizontal direction: Horizontal) according to an embodiment of the present invention. It is a drawing shown.

Referring to the left drawing of FIG. 21, an AABB box composed of points furthest in a vertical direction in the curvature map of the posterior tooth may be generated. Using the AABB box created in this way, it is possible to determine the vertical inclination of the posterior teeth visible from the upper surface.

Referring to the right drawing of FIG. 21, an AABB box composed of points that are furthest in the horizontal direction in the curvature map of the posterior tooth can be made. Using the AABB box created in this way, it is possible to determine the horizontal inclination of the posterior teeth viewed from the upper surface.

22 is a diagram illustrating a ratio of the number of convex points and the number of concave points of a posterior tooth according to an embodiment of the present invention.

Referring to FIG. 22, convex points and concave points are separated from the curvature map of the posterior tooth, and convex using the ratio of the number of convex points and the number of concave points (Convex point Number / Concave point Number). You can calculate the ratio of the part to the concave part.

23 is a diagram illustrating the number of curvature points of a child box of a posterior tooth according to an embodiment of the present invention.

Referring to FIG. 23, rather than analyzing the total number of curvature points in the curvature map, a more accurate result may be obtained by dividing the curvature map into a small range of child boxes and then comparing the number of curvature points. At this time, the user can define the rows and columns for separating the upper surface of the crown, and calculate and compare the number of points in each child box.

24 is a diagram illustrating a child box convex concave points ratio of a child box of a posterior tooth according to an embodiment of the present invention.

Referring to FIG. 24, the ratio of convex points and concave points in each child box range can be known through the ratio of convex points and concave points of a child box (Convex points / Concave points).

25 is a diagram illustrating an example of a result of recommending a posterior tooth according to an embodiment of the present invention.

The results of recommending the posterior teeth obtained through the analysis of the six characteristics of the posterior teeth described above with reference to FIGS. 18 to 24 are as shown in FIG. 25. As shown in FIG. 25, a recommendation result may be provided in the form of a recommendation list. At this time, it is possible to provide a list of recommendations in order by assigning a ranking.

26 is a diagram illustrating an example of a crown template recommendation scenario according to an embodiment of the present invention.

Referring to FIG. 26, the prosthetic CAD device automatically selects an optimal crown template model from a crown template list through a feature analysis and comparison algorithm and presents a recommendation list to the user. At this time, the user can easily select a desired crown model from the recommendation list. If there is no desired crown template model in the recommendation list, the user can manually find the desired crown model from the crown template list or adjust the weight of each feature in the recommendation algorithm to find the desired crown model. Alternatively, the prosthetic CAD device can automatically adjust the specific gravity of each feature and recommend a different crown model.

27 is a diagram illustrating an example in which a user corrects the weight of each feature according to an embodiment of the present invention.

Referring to FIG. 27, the developer can optimize the weight of the element for selecting the tooth feature, but the weight of the element occupying the tooth feature must be different because the user's personal preference is different. Therefore, not all users can be satisfied with one weight of tooth feature. Therefore, if the user is not satisfied with the result recommended by the software, the weight can be manually adjusted and tested several times to find a weight suitable for his or her taste.

Referring to FIG. 28, the prosthetic CAD device analyzes the user's selection record, performs learning, for example, artificial intelligence (AI)-based machine learning, and then automatically adjusts the weight according to the taste of the user. You can recommend results that suit your personal taste. Since each user has a different taste for selecting a crown model, there are cases where the recommended tooth template model is satisfied or not. If not satisfied, the user has to adjust the weight of the crown feature or select a crown template model other than the recommendation list, which may take a lot of time to select the crown model. In order to solve this problem, if the user's history history including the user's crown selection record is analyzed and the weight of the tooth feature is automatically adjusted based on the analysis result, the recommendation list may become closer to the user's taste.

So far, the present invention has been looked at around the embodiments. Those of ordinary skill in the art to which the present invention pertains will be able to understand that the present invention may be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered from an illustrative point of view rather than a limiting point of view. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

Claims

Separating the teeth from the dental image;

Tooth features are extracted by analyzing tooth images for each anterior or posterior tooth according to whether at least one of the same teeth, peripheral teeth, and opposing teeth of the tooth requiring prosthetics is an anterior or posterior tooth from a separated dental image. Step to do;

Comparing the tooth model from which tooth features are extracted with template models in the crown template list; And

Recommending a crown template model from the crown template list by reflecting the tooth analysis and comparison results;

Crown model automatic recommendation method comprising a.
The method of claim 1, wherein extracting tooth features

Automatic crown model recommendation method, characterized in that the tooth shape is analyzed in the order of the same tooth, peripheral tooth, and opposing tooth of the target tooth.
The method of claim 1, wherein extracting tooth features

If the tooth to be analyzed is an anterior tooth, extracting boundary points of the front surface of the anterior tooth to analyze the labial shape;

Among the boundary points, a bounding box is created with the two points that are farthest in the horizontal direction of the anterior and three points including the highest point in the vertical direction, and the upper part of the anterior tooth using the ratio of the height and width of the created bounding box. Extracting a shape feature of; And

Generating a bounding box from two points that are farthest from the horizontal direction of the anterior tooth among the boundary points, and extracting a slope feature of the shape of an upper part of the anterior tooth using a ratio of the height and width of the created bounding box;

Crown model automatic recommendation method comprising a.
The method of claim 1, wherein extracting tooth features

If the tooth to be analyzed is an anterior tooth, extracting boundary points of the front surface of the anterior tooth to analyze the labial shape;

Separating a left or right boundary portion from the extracted boundary points by a straight line connecting the leftmost point in the horizontal direction of the anterior teeth and the highest point in the vertical direction; And

Extracting shape features of the left or right boundary of the anterior teeth by obtaining the longest distance from the straight line among boundary points on the left or right boundary portion;

Crown model automatic recommendation method comprising a.
The method of claim 1, wherein extracting tooth features

If the tooth to be analyzed is an anterior tooth, extracting boundary points of side surfaces of the anterior tooth to analyze abrasion; And

Extracting a wear feature of the anterior teeth from the extracted boundary points;

Crown model automatic recommendation method comprising a.
The method of claim 1, wherein extracting tooth features

Generating a curvature map of the posterior tooth if the tooth to be analyzed is a posterior tooth;

Generating a bounding box consisting of four points furthest in the horizontal and vertical directions in the curvature map of the posterior tooth; And

Extracting a shape feature of an upper portion of the posterior tooth using a ratio of the height and width of the generated bounding box;

Crown model automatic recommendation method comprising a.
The method of claim 1, wherein extracting tooth features

If the tooth to be analyzed is a posterior tooth, generating a bounding box consisting of points furthest in a vertical direction from a curvature map of the posterior tooth and extracting a vertical inclination feature of the posterior tooth visible from the upper surface using the generated bounding box; And

Generating a bounding box consisting of points that are furthest in the horizontal direction from the curvature map of the posterior tooth and extracting a horizontal tilt feature of the posterior tooth visible from the upper surface using the generated bounding box;

Crown model automatic recommendation method comprising a.
The method of claim 1, wherein extracting tooth features

If the tooth to be analyzed is the posterior tooth, the convex point and the concave point are separated from the curvature map of the posterior tooth, and the ratio of the number of convex points and the number of concave points is extracted.
The method of claim 1, wherein extracting tooth features

If the tooth to be analyzed is the posterior region, the crown model is automatically recommended, characterized by dividing the curvature map of the posterior region into a number of child boxes and extracting the ratio features of the number of points of the child box and the number of convex and concave points of the child box. Way.
The method of claim 1, wherein the step of recommending a crown template model

In the crown template model recommendation list, if the user does not have a crown template model desired by the user, the weight of each feature is manually or automatically adjusted, and then a new crown template model is recommended.
A data acquisition unit that acquires image data for prosthesis design;

A control unit for extracting features of the tooth to be analyzed in the order of the same tooth value, the peripheral tooth, and the antagonist tooth from the image data, and recommending a crown template model by reflecting the extracted tooth feature; And

An output unit that displays information on the crown template model recommended by the control unit;

Prosthetic CAD device comprising a.
The method of claim 11, wherein the control unit

If the tooth to be analyzed is an anterior tooth, the boundary points of the front of the anterior tooth are extracted,

A prosthetic CAD device, characterized in that for extracting features by numerically quantifying at least one of a height and width ratio of a bounding box, a left boundary point-straight line distance, and a right boundary point-straight line distance of the anterior tooth using the extracted boundary points.
The method of claim 11, wherein the control unit

If the tooth to be analyzed is the posterior region, a curvature map of the posterior region is created,

Extracting the shape features of the upper part of the posterior part by using the ratio of the height and width of the bounding box created from the curvature map of the posterior part, and extracting the vertical and horizontal inclination features of the posterior teeth visible from the upper surface using the bounding box. Prosthetic CAD device characterized by.
The method of claim 11, wherein the control unit

If the tooth to be analyzed is the posterior region, a curvature map of the posterior region is created,

After separating the convex point and the concave point from the curvature map of the posterior tooth, the ratio of the number of convex points and the number of concave points is extracted,

After dividing the curvature map of the posterior teeth into a plurality of child boxes, a ratio feature of the number of points of the child box and the number of convex points and the number of concave points of the child box is extracted.
The method of claim 11, wherein the control unit

If there is no crown template model desired by the user in the crown template model recommendation list, a new crown template model is recommended after manually or automatically adjusting the weight of each feature.